顔写真

ヤマモト サトル
山本 悟
Satoru Yamamoto
所属
大学院情報科学研究科 情報基礎科学専攻 情報応用数理学講座(計算数理科学分野)
職名
教授
学位
  • 工学博士(東北大学)

経歴 6

  • 2004年10月 ~ 継続中
    東北大学大学院情報科学研究科 教授

  • 1992年12月 ~ 2004年9月
    東北大学 大学院工学研究科航空宇宙工学専攻 助教授

  • 1992年4月 ~ 1993年1月
    スタンフォード大学航空宇宙学科 文部省在外研究員(若手枠) 客員研究員

  • 1991年4月 ~ 1992年11月
    東北大学 工学部機械航空工学科 講師

  • 1989年4月 ~ 1991年3月
    東北大学 工学部機械工学科 助手

  • 1987年4月 ~ 1989年3月
    東北大学 日本学術振興会特別研究員

︎全件表示 ︎最初の5件までを表示

学歴 2

  • 東北大学 大学院工学研究科 機械工学専攻博士課程後期3年の課程修了

    ~ 1989年3月

  • 東北大学 工学部 機械工学科卒業

    ~ 1984年3月

委員歴 75

  • 日本ガスタービン学会 代表執行理事

    2022年4月 ~ 継続中

  • 日本機械学会 流体工学部門・部門長

    2021年4月 ~ 2022年3月

  • 日本学術振興会 特別研究員等審査専門委員

    2017年8月 ~ 2019年7月

  • 国際電気基準会議(IEC) TC5日本委員会委員

    2017年4月 ~ 2019年3月

  • 日本ガスタービン学会 執行理事

    2017年4月 ~ 2019年3月

  • (財) 高度情報科学技術研究機構HPCI産業利用WG 委員

    2013年4月 ~ 2018年3月

  • 日本流体力学会 第23回数値流体力学シンポジウム実行委員長

    2009年4月 ~ 2010年3月

  • 日本機械学会 論文集B1編編修委員会委員長

    2009年4月 ~ 2010年3月

  • International Conference on Fluid Dynamics International Scientific Committee Member

    2010年4月 ~ 継続中

  • 日本機械学会 流体工学部門副部門長

    2020年4月 ~ 2021年3月

  • 日本機械学会 流体工学部門技術委員会委員長

    2019年4月 ~ 2020年3月

  • 日本機械学会 東北支部庶務幹事

    2018年4月 ~ 2020年3月

  • 日本機械学会 東北支部商議員

    2018年4月 ~ 2020年3月

  • 日本機械学会 東北支部会計幹事

    2015年4月 ~ 2017年3月

  • 日本機械学会 東北支部商議員

    2012年4月 ~ 2017年3月

  • 日本機械学会賞委員会 委員

    2012年4月 ~ 2013年4月

  • 日本機械学会賞委員会 委員

    2012年4月 ~ 2013年4月

  • 日本ガスタービン学会調査研究委員会 委員

    2011年4月 ~ 2013年4月

  • 日本ガスタービン学会 理事

    2009年4月 ~ 2011年3月

  • 日本ガスタービン学会 評議員

    2004年4月 ~ 2011年3月

  • 日本機械学会 計算力学部門運営委員

    2007年4月 ~ 2010年3月

  • 日本機械学会 計算力学部門年次大会担当委員会委員長

    2008年4月 ~ 2009年3月

  • 日本機械学会 論文集B1編編修委員会副委員長

    2008年4月 ~ 2009年3月

  • 日本機械学会 計算力学部門年次大会担当委員会委員長

    2008年4月 ~ 2009年3月

  • 日本機械学会 論文集B1編編修委員会副委員長

    2008年4月 ~ 2009年3月

  • 日本機械学会 東北支部商議員

    2005年4月 ~ 2008年3月

  • 青葉工業会 常任理事

    2005年4月 ~ 2008年3月

  • 日本機械学会 東北支部商議員

    2005年4月 ~ 2008年3月

  • 青葉工業会 常任理事

    2005年4月 ~ 2008年3月

  • 日本機械学会 論文校閲委員

    1995年4月 ~ 2008年3月

  • 日本機械学会 論文校閲委員

    1995年4月 ~ 2008年3月

  • Computational Fluid Dynamics Journal Editorial Advisory Board

    1998年4月 ~ 2006年3月

  • Computational Fluid Dynamics Journal Editorial Advisory Board

    1998年4月 ~ 2006年3月

  • 日本機械学会 流体工学部門技術委員会 WG 委員

    1998年4月 ~ 2004年3月

  • 日本機械学会 流体工学部門技術委員会 WG 委員

    1998年4月 ~ 2004年3月

  • 日本流体力学会 数値流体力学シンポジウム実行委員

    2002年12月 ~ 2003年12月

  • 日本流体力学会 数値流体力学シンポジウム実行委員

    2002年12月 ~ 2003年12月

  • 東北地域総合エネルギー対策推進会議 委員

    2001年4月 ~ 2002年3月

  • 東北地域総合エネルギー対策推進会議 委員

    2001年4月 ~ 2002年3月

  • 日本航空宇宙学会 北部支部講演会実行委員

    1999年3月 ~ 2001年3月

  • 日本航空宇宙学会 北部支部講演会実行委員

    1999年3月 ~ 2001年3月

  • 日本航空宇宙学会 北部支部幹事

    1998年4月 ~ 2001年3月

  • 日本航空宇宙学会 北部支部幹事

    1998年4月 ~ 2001年3月

  • 日本航空宇宙学会 会誌編集委員

    1996年4月 ~ 1998年3月

  • 日本航空宇宙学会 会誌編集委員

    1996年4月 ~ 1998年3月

  • 日本機械学会 研究協力部会「RC140 混相流動解析プログラムの高度化と応用に関する研究分科会」 研究者側委員

    1996年7月 ~ 1997年6月

  • 日本機械学会 研究協力部会「RC140 混相流動解析プログラムの高度化と応用に関する研究分科会」 研究者側委員

    1996年7月 ~ 1997年6月

  • 日本機械学会 流体工学部門技術委員会委員

    1995年4月 ~ 1996年3月

  • 日本機械学会 流体工学部門技術委員会委員

    1995年4月 ~ 1996年3月

  • 日本航空宇宙学会 北部支部幹事

    1993年4月 ~ 1996年3月

  • 日本航空宇宙学会 北部支部幹事

    1993年4月 ~ 1996年3月

  • 日本航空宇宙学会 北部支部講演会実行委員会委員

    1994年3月 ~ 1996年2月

  • 日本航空宇宙学会 北部支部講演会実行委員会委員

    1994年3月 ~ 1996年2月

  • 日本機械学会 究協力部会分科会 「RC124 流れ解析データベース研究分科会」委員

    1993年7月 ~ 1995年6月

  • 日本機械学会 究協力部会分科会 「RC124 流れ解析データベース研究分科会」委員

    1993年7月 ~ 1995年6月

  • 日本機械学会 流体工学部門広報委員会委員

    1993年4月 ~ 1995年3月

  • 日本機械学会 流体工学部門広報委員会委員

    1993年4月 ~ 1995年3月

  • 日本機械学会 流体工学部門運営委員

    2011年4月 ~

  • 日本機械学会 流体工学部門運営委員

    2011年4月 ~

  • 日本機械学会 流体工学部門講演会実行委員会幹事

    2001年10月 ~

  • 日本機械学会 流体工学部門講演会実行委員会幹事

    2001年10月 ~

  • 日本機械学会 創立 100 周年記念東北支部記念事業委員会委員

    1997年10月 ~

  • 日本機械学会 創立 100 周年記念東北支部記念事業委員会委員

    1997年10月 ~

  • Int. Symp. on Mathematical Modeling of Turbulent Flows Steering Committee Member

    1995年12月 ~

  • 乱流の数理モデルに関する国際シンポジウム 組織委員

    1995年12月 ~

  • 日本航空宇宙学会 北部支部主催一般市民向け第 3 回科学講演会実行委員会委員長

    1995年10月 ~

  • 日本航空宇宙学会 北部支部主催一般市民向け第 3 回科学講演会実行委員会委員長

    1995年10月 ~

  • The Third JSME-KSME Fluids Engineering Conference Excecutive Committee Member

    1994年7月 ~

  • 第3回JSME-KSME流体工学会議 実行委員

    1994年7月 ~

  • 日本機械学会 東北支部第 29 期総会 . 講演会実行委員会委員

    1994年3月 ~

  • 日本機械学会 東北支部第 29 期総会 . 講演会実行委員会委員

    1994年3月 ~

  • The 5th Int. Symposium on Computational Fluid Dynamics-Sendai Executive Committee Member

    1993年8月 ~

  • 第5回国際数値流体力学会議 実行委員

    1993年8月 ~

  • 日本流体力学会 第 25 回乱流シンポジウム実行委員会委員

    1993年7月 ~

  • 日本流体力学会 第 25 回乱流シンポジウム実行委員会委員

    1993年7月 ~

︎全件表示 ︎最初の5件までを表示

所属学協会 4

  • 日本工学アカデミー

  • 日本航空宇宙学会

  • 日本ガスタービン学会

  • 日本機械学会

研究キーワード 7

  • 数値流体力学

  • マルチフィジックスCFD

  • 計算数理科学

  • 数値計算

  • 超臨界流体

  • ガスタービン

  • 蒸気タービン

研究分野 3

  • フロンティア(航空・船舶) / 航空宇宙工学 / ガスタービン

  • ものづくり技術(機械・電気電子・化学工学) / 熱工学 / 超臨界流体

  • ものづくり技術(機械・電気電子・化学工学) / 流体工学 / 数値流体力学

受賞 9

  1. 日本機械学会流体工学部門賞

    2023年7月 日本機械学会

  2. 日本ガスタービン学会功労賞

    2022年11月 日本ガスタービン学会

  3. 2018年最優秀論文賞

    2020年3月 英国機械学会

  4. 平成30年度特別研究員等審査会専門委員表彰

    2019年9月 日本学術振興会

  5. Advanves in Engineering, Key Scientific Article

    2018年9月

  6. Advances in Engineering, Key Scientific Article

    2015年4月

  7. 計算力学技術者(CAE技術者)上級アナリスト

    2009年9月 日本機械学会

  8. 日本ガスタービン学会賞奨励賞(The GTSJ Prize, the incentive prize)

    1996年4月 日本ガスタービン学会(Gas Turbine Society of Japan)

  9. 日本機械学会賞奨励賞(The JSME Prize, the incentive prize)

    1990年3月 日本機械学会(Japan Society of Mechanical Engineers

︎全件表示 ︎最初の5件までを表示

論文 174

  1. Self-organization of Unsteady Full-Annulus Flows in A Gas Turbine Compressor under Operating Conditions 査読有り

    Yasuharu Hagita, Riku Hayakawa, Hironori Miyazawa, Takashi Furusawa, Satoru Yamamoto

    Proceedings of ASME 2023 Turbo Expo GT2023-101937 1-11 2023年6月

  2. Modified heat transfer correction function for modeling multiphase condensing flows in transonic regime 査読有り

    Piotr Wiśniewski, Sławomir Dykas, Hironori Miyazawa, Takashi Furusawa, Satoru Yamamoto

    International Journal of Heat and Mass Transfer 201 123597-123597 2023年2月

    出版者・発行元:Elsevier BV

    DOI: 10.1016/j.ijheatmasstransfer.2022.123597  

    ISSN:0017-9310

    詳細を見る 詳細を閉じる

    Water droplet formation and growth in the nucleation process are crucial aspects of steam condensation in moist air flow, and they are accompanied by intensive heat exchange between phases. This study proposes a mathematical model for predicting heat transfer coefficients in the condensation process, which is applicable for single-phase and multiphase flows. The proposed model based on the correction function forms a continuous model for the low Knudsen number regime, and in the region of large Knudsen numbers, it employs a simplified droplet growth model based on Hertz and Knudsen's approach derived from the kinetic theorem. The proposed model was compared with existing models based on the continuous approach, that is, models derived by Gyarmathy, Fuchs-Sutigin, and Young, as well as models based on the kinetic theorem. Furthermore, the proposed model was implemented into a numerical CFD tool, and numerical studies were conducted for two representative cases of single-species and multispecies flows, that is, steam and humid-air expansion in a converging-diverging nozzle. For steam studies, the proposed model showed a similar convergence with the experiment as Young's model however, its agreement with the experimental results for multispecies condensation flow was better. The proposed model is promising for the study of condensation when there is rapid droplet growth, which occurs in multispecies flows, even if further study is needed to find a correlation between the condensation coefficient and fluid properties.

  3. Numerical Modeling of Water Droplets in Compressible Two-Phase Flows Based on Eulerian-Eulerian Method 査読有り

    Takashi Furusawa, Yasuhiro Sasao, Ryo Takata, Hironori Miyazawa, Satoru Yamamoto

    Proceedings of ASME 2022 Turbo Expo GT2022-81246 1-9 2022年6月

    DOI: 10.1115/GT2022-81246  

  4. The Effect of Partial-Load Operation on a Gas Turbine Compressor of an Advanced Combined Cycle Power Plant 査読有り

    Yasuharu Hagita, Hironori Miyazawa, Takashi Furusawa, Satoru Yamamoto, Koichi Yonezawa, Shuichi Umezawa, Shuichi Ohmori, Takeshi Suzuki

    Proceedings of ASME 2022 Turbo Expo GT2022-80251 1-12 2022年6月

    DOI: 10.1115/GT2022-80251  

  5. Double-flux model for supercritical multicomponent flows at low Mach numbers with preconditioning method 査読有り

    Shuto Yatsuyanagi, Takashi Furusawa, Satoru Yamamoto

    Journal of Computational Physics 458 111091-111091 2022年6月

    出版者・発行元:Elsevier BV

    DOI: 10.1016/j.jcp.2022.111091  

    ISSN:0021-9991

  6. Detection of Machinery Failure Signs From Big Time-Series Data Obtained by Flow Simulation of Intermediate-Pressure Steam Turbines 査読有り

    Kazuhiko Komatsu, Hironori Miyazawa, Cheng Yiran, Masayuki Sato, Takashi Furusawa, Satoru Yamamoto, Hiroaki Kobayashi

    Journal of Engineering for Gas Turbines and Power 144 (1) 2022年1月1日

    出版者・発行元:ASME International

    DOI: 10.1115/1.4052142  

    ISSN:0742-4795

    eISSN:1528-8919

    詳細を見る 詳細を閉じる

    <title>Abstract</title> The periodic maintenance, repair, and overhaul (MRO) of turbine blades in thermal power plants are essential to maintain a stable power supply. During MRO, older and less-efficient power plants are put into operation, which results in wastage of additional fuels. Such a situation forces thermal power plants to work under off-design conditions. Moreover, such an operation accelerates blade deterioration, which may lead to sudden failure. Therefore, a method for avoiding unexpected failures needs to be developed. To detect the signs of machinery failures, the analysis of time-series data is required. However, data for various blade conditions must be collected from actual operating steam turbines. Further, obtaining abnormal or failure data is difficult. Thus, this paper proposes a classification approach to analyze big time-series data alternatively collected from numerical results. The time-series data from various normal and abnormal cases of actual intermediate-pressure steam-turbine operation were obtained through numerical simulation. Thereafter, useful features were extracted and classified using K-means clustering to judge whether the turbine is operating normally or abnormally. The experimental results indicate that the status of the blade can be appropriately classified. By checking data from real turbine blades using our classification results, the status of these blades can be estimated. Thus, this approach can help decide on the appropriate timing for MRO.

  7. Numerical study of supercritical octane flows with multicomponent effects by pyrolysis 査読有り

    Shuto Yatsuyanagi, Takashi Furusawa, Hironori Miyazawa, Satoru Yamamoto, Takuo Onodera, Sadatake Tomioka

    International Journal of Thermal Sciences 171 107193-107193 2022年1月

    出版者・発行元:Elsevier BV

    DOI: 10.1016/j.ijthermalsci.2021.107193  

    ISSN:1290-0729

    詳細を見る 詳細を閉じる

    This study focuses on supercritical octane flow simulation with pyrolysis reactions in a heated circular pipe to determine the multicomponent effects of changes in thermophysical properties. The reaction rate of n-octane for pyrolysis was estimated by a zeroth-dimensional simulation of hydrocarbon pyrolysis. The resulting mole fractions of the decomposed components were compared with the experimental data. The mole fraction results were then used to develop three thermophysical property models for the mixture of unreacted n-octane and decomposed hydrocarbons, i.e., 1-, 4-, and 12-component models. In the supercritical octane flow simulations, the multicomponent thermophysical properties of each component model were determined using the polynomial equations in the Reference Fluid Thermodynamic and Transport Properties Database. The conventional k−ω SST model and k−ωSST+Mτ model served as the Reynolds-averaged Navier–Stokes turbulence models. In cases with a low wall temperature, the outlet temperatures in all component models were consistent with the experimental data, in which pyrolysis did not occur. In cases with a high wall temperature above 973 K, the density change and production of kinetic energy affected the turbulent thermal diffusivity in the heated pipe. In cases where the multicomponent effects of thermophysical properties and turbulence were considered, the numerical method reproduced a reasonable outlet temperature and conversion rate, whereas the experimental results were underestimated in all the other cases. These numerical results indicate that the accurate prediction of density changes and the production of turbulent kinetic energy are the key issues in reproducing thermal fluid flows of supercritical hydrocarbons with pyrolysis reactions in uniform wall temperature cases.

  8. Effects of wetness and humidity on transonic compressor of gas turbine 査読有り

    Satoru Yamamoto, Koki Araki, Shota Moriguchi, Hironori Miyazawa, Takashi Furusawa, Koichi Yonezawa, Shuichi Umezawa, Shuichi Ohmori, Takeshi Suzuki

    International Journal of Heat and Mass Transfer 178 121649-121649 2021年10月

    出版者・発行元:Elsevier BV

    DOI: 10.1016/j.ijheatmasstransfer.2021.121649  

    ISSN:0017-9310

    詳細を見る 詳細を閉じる

    Moist air flows with and without consideration of inlet wetness and assuming fogging were numerically investigated in a transonic compressor of an industrial gas turbine, and the causal relationship between the wetness and the deposition of water droplets on the blade surface was clarified. First, we simulated three-dimensional moist-air flows through the 1.5-stage rotor and stator blade rows in the transonic compressor of an industrial gas turbine operating at a Tokyo Electrical power plant, considering variations in the inlet wetness and the number of aerosol particles. The results indicated that the shock generated in the first-stage rotor passage was the primary factor in the evaporation of the moist air, decreasing its temperature, whereas the wetness was highly dependant on the deposition of water droplets on the blade surface. We further simulated two-dimensional humid-air flows through a transonic compressor cascade channel under a number of conditions, varying the aerosol particle size, number of aerosol particles, humidity, blade chord length and pressure ratio. The results indicated that the condensation of humid air was captured locally in the supersonic region, while the deposition of the condensed water droplets was mainly influenced by the first three factors. Overall, this study indicates that wetness and deposition are in a trade-off relationship with regard to the performance of gas turbines.

  9. Numerical Investigation of Supercritical n-Dodecane Flows in a Heated Circular Pipe with Thermal Cracking 査読有り

    Shuto Yatsuyanagi, Takashi Furusawa, Satoru Yamamoto, Takuo Onodera, Sadatake Tomioka

    Proceedings of ASME Fluids Engineering Division Summer Meeting (FEDSM2021), Virtual Conference FEDSM2021-65261 1-9 2021年8月10日

  10. Turbulent Flow Simulation of Supercritical Hydrothermal Synthesis in T-Shaped Channel 査読有り

    Takashi Furusawa, Kenta Matsui, Shuto Yatsuyanagi, Satoru Yamamoto, Akira Yoko, Tadafumi Adschiri

    Proceedings of ASME Fluids Engineering Division Summer Meeting (FEDSM2021), Virtual Conference FEDSM2021-66023 1-7 2021年8月10日

    出版者・発行元:American Society of Mechanical Engineers

    DOI: 10.1115/fedsm2021-66023  

    詳細を見る 詳細を閉じる

    <title>Abstract</title> Turbulent mixing flows of supercritical water and a metal-salt solution were investigated using Reynolds-averaged Navier–Stokes (RANS) simulations. The mass conservation equations for metal-salt and metal-oxide in an aqueous solution, which were coupled with Navier–Stokes equations and the Shear Stress Transport (SST) turbulence model, were solved by considering production by the hydrothermal reaction. The reaction rate in the numerical simulation was interpolated linearly using the experimental data. The mixing flows in a T-shaped channel for various Reynolds numbers were simulated numerically. Fluid mixing causes a hydrothermal reaction in a high temperature region. In a situation with a low temperature and low Reynolds number, the mixing became a steady state, and the metal oxide was generated along the channel wall. For a high Reynolds number, the periodic vortexes were observed at the mixing point and the fluid temperature increased rapidly. A numerical simulation reproduced the apparent reaction rate of the experimental measurements, except for the low Reynolds number case. The time-averaged temperature distributions indicated that the increasing temperature rate in the mixing reactor depends on the inlet supercritical water temperature, which affects the distribution of the concentration of metal oxide. If the turbulence effects were ignored in low-temperature instances, the apparent reaction rate was estimated to be quite low. The turbulent diffusivity and thermal conductivity crucially affected the conversion rate, especially for conditions with a low Reynolds number.

  11. Detection of Machinery Failure Signs from Big Time-series Data Obtained by Flow Simulation of Intermediate-pressure Turbines 査読有り

    Proceedings of ASME 2021 Turbo Expo GT2021-58698 1-11 2021年6月

    DOI: 10.1115/GT2021-58698  

  12. Large eddy simulation of a linear turbine cascade with a trailing edge cutback 査読有り

    Shota Moriguchi, Hironori Miyazawa, Takashi Furusawa, Satoru Yamamoto

    Energy 220 119694-119694 2021年4月

    出版者・発行元:Elsevier BV

    DOI: 10.1016/j.energy.2020.119694  

    ISSN:0360-5442

    詳細を見る 詳細を閉じる

    In this work, the effects of trailing edge (TE) cutback on the turbulent flow field and the aerodynamic loss of a turbine blade are investigated by Large-Eddy-Simulation (LES). A high-fidelity LES code was first developed based on a high-order finite difference method and applied to the simulation. The effects of the TE cutback on the blade surface boundary layer, pressure distribution, and loss generation are then discussed on the basis of time-mean flow fields of LES. The results represent that the cutback changed the boundary layer thickness just upstream of the TE and the base pressure around the TE, resulting in larger aerodynamic loss. Next, the time-dependent flow dynamics in the cascade is investigated. The results indicate that the dominant pressure fluctuation after the blade was influenced by the cutback. Furthermore, the phase-locked flow field is analyzed to reveal the flow dynamics responsible for the pressure fluctuation. Finally, the LES approach could clarify the underlying mechanisms of performance degradation of a turbine blade that caused by TE cutback.

  13. Unsteady flow simulation of industrial gas turbine compressor under start-up operation

    Hironori Miyazawa, Koki Araki, Takashi Furusawa, Satoru Yamamoto, Shuichi Umezawa, Koichi Yonezawa, Shuichi Ohmori, Takeshi Suzuki

    Proceedings of the International Conference on Power Engineering 2021, ICOPE 2021 2021年

    詳細を見る 詳細を閉じる

    In this paper, unsteady flows in the actual gas turbine compressor operating at an advanced combined cycle power station were simulated under the conditions of full-load operation and three different start-up operations. The three cases considered were a low flow-rate condition with the designed rotational speed (3000 rpm), the half of design rotational speed condition (1500 rpm), and further a lower rotational speed condition (700 rpm). In this study, the inlet guide vane (IGV), first-stage rotor and stator, and second-stage rotor were considered. As a result, unsteady flows were captured for all three cases. The obtained unsteady flow results were visualized at the first stage. In the results, rotating stall cells were visualized in the cases of the rotating speed at 3000 rpm and 700 rpm. Particularly in the former case, six stall cells were rotated at a speed of 110% faster than that of the rotor blade. Such unsteady stall cells obviously affected to the downstream flows and induced the pressure fluctuations on the blades.

  14. Numerical approaches for moist air condensing flows modelling in the transonic regime 査読有り

    P. Wiśniewski, S. Dykas, S. Yamamoto, B. Pritz

    International Journal of Heat and Mass Transfer 162 120392-120392 2020年12月

    出版者・発行元:Elsevier BV

    DOI: 10.1016/j.ijheatmasstransfer.2020.120392  

    ISSN:0017-9310

  15. Wetness Measurement and Droplet Transport Analysis in Actual Steam Test on A Scaled Low Pressure Turbine 査読有り

    Yasuhiro Sasao, Kiyoshi Segawa, Takeshi Kudo, Ryo Takata, Masaki Osako, Satoru Yamamoto

    Proceedings of ASME 2020 Turbo Expo GT2020-16117 1-12 2020年9月

  16. Unsteady Flow Simulation through Stator-Rotor Blade Rows in Intermediate-Pressure Steam Turbines with Cutback Blades 査読有り

    Hironori Miyazawa, Akihiro Uemura, Takashi Furusawa, Satoru Yamamoto, Koichi Yonezawa, Shuichi Umezawa

    Proceedings of ASME 2020 Turbo Expo GT2020-14937 1-12 2020年9月

    DOI: 10.1115/GT2020-14937  

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    Stator and rotor blades in intermediate-pressure steam turbines gradually deteriorate during operation because of solid particle erosion. In addition to that, turbine blades unexpectedly crack because of metal fatigue or thermal stress deformation. As eroded blades increase the aerodynamic losses and cracked blades may induce rupture of the blade, the periodic maintenance, repair, and overhaul of steam turbines is essential. Eroded or cracked blades should be replaced with new ones or repaired for further use. Cutback treatment is one of the repair methods wherein the deteriorated trailing edge on a turbine blade is removed to avoid further cracking and blade fracturing. The use of cutback blades can reduce the replacement cost; however, that may affect the steam flow and the turbine’s performance. In this study, we numerically investigated the effect of the blade deterioration on the performance of a three-stage intermediate-pressure steam turbine using a numerical method that was developed at Tohoku University. Further various cutback lengths were considered for the deteriorated first-stage stator-blade trailing edge. The obtained numerical results indicate that the cutback first-stage stator blades certainly affected the steam flow in the turbine, resulting in a negative influence on the torque obtained from the adjacent rotor blades, which depends on the cutback length. However, the torque decrement can be mitigated by arranging the cutback and non-cutback stator blades alternately in a row.

  17. Importance of Air Humidity and Contaminations in the Internal and External Transonic Flows 査読有り

    P. Wiśniewski, S. Dykas, S. Yamamoto

    Energies 13 (12) 3153-3153 2020年6月17日

    出版者・発行元:MDPI AG

    DOI: 10.3390/en13123153  

    eISSN:1996-1073

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    The paper presents mathematical modelling of steam condensation in the atmospheric air transonic flows. A single-fluid model was employed. The model was validated against the in-house experimental studies of internal flow in nozzles and against benchmark tests available in literature i.e., RAE2822 transonic airfoil. The impact of air relative humidity on the condensation process under transonic flow conditions was examined. The paper shows that the impact of the condensation process in air transonic flow is non-negligible and has to be taken under consideration in flow simulations. The presence of air contaminants in form of small particles was considered too. Their crucial role in the change of the transonic flow structure was numerically confirmed.

  18. A numerical and analytical coupling method for predicting the performance of intermediate-pressure steam turbines in operation 査読有り

    Satoru Yamamoto, Akihiro Uemura, Hironori Miyazawa, Takashi Furusawa, Koichi Yonezawa, Shuichi Umezawa, Shuichi Ohmori, Takeshi Suzuki

    Energy 198 117380-117380 2020年5月

    出版者・発行元:Elsevier BV

    DOI: 10.1016/j.energy.2020.117380  

    ISSN:0360-5442

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    This study proposes a numerical and analytical coupling method for simulating unsteady steam flow through three-stage stator and rotor blade rows of an intermediate-pressure steam turbine operating in a power plant by considering both the secular-changed blades and the leakage flows in labyrinth seals. The flow simulation was based on the in-house CFD code developed by Tohoku University, whereas the leakage flows in labyrinth seals were predicted by an analytical method. The effects of secular-changed blades and leakage flows on unsteady steam flows are discussed on the basis of time-dependent solutions. Next, the total performances obtained under conditions using manufactured and secular-changed blades both with and without leakage flows were compared with the actual data measured in operation. The obtained results indicate that the increase in static temperature at the outlet of actual intermediate-pressure steam turbines during a long-time operation is obviously caused by the secular change of blades. This paper presents the first results based on a numerical approach to clarify the temperature increase in a working intermediate-pressure steam turbine.

  19. Simulation of unsteady flows through three-stage middle pressure steam turbine in operation 査読有り

    Akihiro UEMURA, Hironori MIYAZAWA, Takashi FURUSAWA, Satoru YAMAMOTO, Koichi YONEZAWA, Shuichi UMEZAWA, Shuichi OHMORI

    Mechanical Engineering Journal 884-889 2020年

    出版者・発行元:Japan Society of Mechanical Engineers

    DOI: 10.1299/mej.20-00068  

    eISSN:2187-9745

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    The purpose of this study is to simulate unsteady steam flows through three-stage stator and rotor blade passages in a middle-pressure steam turbine operated in a power plant while considering manufactured and secular-changed blade shapes. The shapes of the manufactured and secular-changed blades are measured during overhaul. The numerical method is based on an in-house code developed by Tohoku University. The time-dependent pressure and the Mach number are visualized and the difference of the results obtained by assuming manufactured and secular-changed blades is explained. The simulated static temperatures assuming the blades shapes are then compared with each other and with the measured data. In addition, a simple method modifying the simulated static temperature considering real gas effect is proposed.

  20. Numerical Simulation of Unsteady Moist-air Flows through Whole-annulus Rotor Blade Rows in Transonic Compressor 査読有り

    Shota Moriguchi, Takuro Endo, Hironori Miyazawa, Takashi Furusawa, Satoru Yamamoto

    Proc. ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference 5 (AJKFluids2019-4782) 1-9 2019年7月

    DOI: 10.1115/AJKFluids2019-4782  

  21. Numerical Simulation of Supercritical Octane Flows in a Heated Circular Tube with Simple Thermal Cracking Model 査読有り

    Takashi Furusawa, Noriyuki Taki, Shuto Yatsuyanagi, Satoru Yamamoto, Takuto Miyaura, Sadatake Tomioka

    Proc. ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference (AJKFluids2019-4797) 1-8 2019年7月

  22. Optical Couarse Droplet Measurement and Wet Loss Analysis on the Wet Air Flow Through the Subsonic Blade Cascade Channel 査読有り

    Yasuhiro Sasao, Ryo Takata, Satoshi Miyake, Soichiro Tabata, Satoru Yamamoto

    Proc. ASME 2019 Turbo Expo (GT2019-91928) 1-12 2019年6月

  23. Effect of Blade Secular Change on Unsteady Flows in Middle Pressure First-Stage Steam Turbines 査読有り

    Akihiro Uemura, Hironori Miyazawa, Takashi Furusawa, Satoru Yamamoto, Koichi Yonezawa, Shuichi Umezawa

    Proc. ASME 2019 Turbo Expo 8 (GT2019-90644) 1-9 2019年6月

    DOI: 10.1115/GT2019-90644  

  24. Wetness Effect on Transonic Moist-air Flow through a Compressor Rotor 査読有り

    Shota Moriguchi, Hironori Miyazawa, Takashi Furusawa, Satoru Yamamoto

    Proc. ASME 2018 5th-Joint US-European Fluid Engineering Division Summer Meeting 3 (FEDSM2018-83422) 1-10 2018年7月

    DOI: 10.1115/FEDSM2018-83422  

    ISSN:0888-8116

  25. Numerical Method for Simulating High Pressure CO2 Flows with Nonequilibrium Condensation 査読有り

    Takashi Furusawa, Hironori Miyazawa, Satoru Yamamoto

    Proc. ASME 2018 Turbo Expo 9 (GT2018-75592) 1-10 2018年6月

    DOI: 10.1115/GT2018-75592  

  26. Results of the International Wet Steam Modeling Project 国際誌 国際共著 査読有り

    Jorg Startzmann e, l, cluding, Satoru Yamamoto

    Proc. IMechE, Part A, Journal of Power and Energy 1-21 2018年3月

    DOI: 10.1177/0957650918758779  

  27. Numerical Investigation of Transonic Supercritical CO2 Flows with Nonequilibrium Condensation in a Laval Nozzle 査読有り

    Hironori Miyazawa, Takashi Furusawa, Satoru Yamamoto

    Proc. 6th International Supercritical CO2 Power Cycles Symposium 2018年

  28. Effect of Inlet Wetness on Transonic Wet-steam and Moist-air Flows in Turbomachinery 査読有り

    Satoru Yamamoto, Shota Moriguchi, Hironori Miyazawa, Takashi Furusawa

    International Journal of Heat and Mass Transfer (Featured online on 'Advances in Engineering':https://advanceseng.com/free-energy-dominates-nucleation-condensation/) 19 720-732 2018年

    DOI: 10.1016/j.ijheatmasstransfer.2017.12.001  

    ISSN:0017-9310

  29. FPGA-Based Scalable and Power-Efficient Fluid Simulation using Floating-Point DSP Blocks 査読有り

    Kentaro Sano, Satoru Yamamoto

    IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS 28 (10) 2823-2837 2017年10月

    出版者・発行元:IEEE COMPUTER SOC

    DOI: 10.1109/TPDS.2017.2691770  

    ISSN:1045-9219

    eISSN:1558-2183

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    High-performance and low-power computation is required for large-scale fluid dynamics simulation. Due to the inefficient architecture and structure of CPUs and GPUs, they now have a difficulty in improving power efficiency for the target application. Although FPGAs become promising alternatives for power-efficient and high-performance computation due to their new architecture having floating-point (FP) DSP blocks, their relatively narrow memory bandwidth requires an appropriate way to fully exploit the advantage. This paper presents an architecture and design for scalable fluid simulation based on data-flow computing with a state-of-the-art FPGA. To exploit available hardware resources including FP DSPs, we introduce spatial and temporal parallelism to further scale the performance by adding more stream processing elements (SPEs) in an array. Performance modeling and prototype implementation allow us to explore the design space for both the existing Altera Arria10 and the upcoming Intel Stratix10 FPGAs. We demonstrate that Arria10 10AX115 FPGA achieves 519 GFlops at 9.67 GFlops/Wonly with a stream bandwidth of 9.0 GB/s, which is 97.9 percent of the peak performance of 18 implemented SPEs. We also estimate that Stratix10 FPGA can scale up to 6844 GFlops by combining spatial and temporal parallelism adequately.

  30. Bandwidth Compression of Floating-Point Numerical Data Streams for FPGA-Based High-Performance Computing 査読有り

    Tomohiro Ueno, Kentaro Sano, Satoru Yamamoto

    ACM TRANSACTIONS ON RECONFIGURABLE TECHNOLOGY AND SYSTEMS 10 (3) 2017年7月

    出版者・発行元:ASSOC COMPUTING MACHINERY

    DOI: 10.1145/3053688  

    ISSN:1936-7406

    eISSN:1936-7414

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    Although computational performance is often limited by insufficient bandwidth to/from an external memory, it is not easy to physically increase off-chip memory bandwidth. In this study, we propose a hardware-based bandwidth compression technique that can be applied to field-programmable gate array- (FPGA) based high-performance computation with a logically wider effective memory bandwidth. Our proposed hardware approach can boost the performance of FPGA-based stream computations by applying a data compression technique to effectively transfer more data streams. To apply this data compression technique to bandwidth compression via hardware, several requirements must first be satisfied, including an acceptable level of compression performance and a sufficiently small hardware footprint. Our proposed hardware-based bandwidth compressor utilizes an efficient prediction-based data compression algorithm. Moreover, we propose a multichannel serializer and deserializer that enable applications to use multiple channels of computational data with the bandwidth compression. The serializer encodes compressed data blocks of multiple channels into a data stream, which is efficiently written to an external memory. Based on preliminary evaluation, we define an encoding format considering both high compression ratio and small hardware area. As a result, we demonstrate that our area saving bandwidth compressor increases performance of an FPGA-based fluid dynamics simulation by deployingmore processing elements to exploit spatial parallelism with the enhanced memory bandwidth.

  31. Numerical analysis of condensation effects on final-stage rotor-blade rows in low-pressure steam turbine 査読有り

    Hironori Miyazawa, Takashi Furusawa, Satoru Yamamoto

    Journal of Fluid Science and Technology 12 (2) 1-12 2017年

    出版者・発行元:Japan Society of Mechanical Engineers

    DOI: 10.1299/jfst.2017jfst0018  

    ISSN:1880-5558

    eISSN:1880-5558

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    The causal relationship between unsteady forces of wet-steam flows on rotor-blade rows and the steam condensation in low pressure steam turbines is still one of unresolved issues. In this study, we investigate the effect of condensation on the time-dependent torque of final-stage long-rotor blade rows in a low pressure steam turbine. Then we simulate unsteady wet-steam flows through the three-stage stator-rotor blade rows in the steam turbine while changing the inlet temperature condition. The variation of the inlet temperature results in creating a flow field with a different amount of wetness due to condensation. The temperature and pressure in the flow field obtained from a different inlet temperature are compared with each other, and the torques calculated from the time-dependent pressure on a final-stage long-rotor blade are also relatively compared. The calculated results in this study indicate that the time-dependent torques on the final-stage long-rotor blade significantly depend on the latent heat added by condensation and that the amount of condensation is highly sensitive to variations in the inlet temperature. This study also suggests that an optimal inlet temperature may be exist for optimizing the torque of low pressure steam turbines.

  32. Mathematical modeling and computation of high-pressure steam condensation in a transonic flow 査読有り

    Takashi Furusawa, Satoru Yamamoto

    Journal of Fluid Science and Technology 12 (1) 1-11 2017年

    出版者・発行元:Japan Society of Mechanical Engineers

    DOI: 10.1299/jfst.2017jfst0002  

    ISSN:1880-5558

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    Wet-steam flows under high-pressure conditions are numerically investigated using a newly derived condensation model that assumes a real gas and uses a real gas Equation of State (EOS). Under high-pressure conditions, the present condensation model calculates the critical radius of a water droplet that is larger than that of the conventional model. The results indicate that nucleation is initiated farther downstream in the nozzle and the nucleation rate is smaller. Wet-steam nozzle flows under high-pressure conditions are simulated and the results are compared with experimental results. The present model simulates the pressure increase due to the release of latent heat of condensation more accurately than the conventional method based on the ideal gas assumption. The results obtained are also in good agreement with the experimental results.

  33. NUMERICAL METHOD FOR SIMULATING FLOWS OF SUPERCRITICAL CO2 COMPRESSOR WITH NONEQUILIBRIUM CONDENSATION 査読有り

    Takashi Furusawa, Hironori Miyazawa, Satoru Yamamoto

    PROCEEDINGS OF THE ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2016, VOL 9 (GT2016-56431) 331-339 2016年

    出版者・発行元:AMER SOC MECHANICAL ENGINEERS

    DOI: 10.1115/GT2016-56431  

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    We recently proposed a numerical method for simulating flows of supercritical CO2 based on a preconditioning method and the thermophysical models programed in a program package for thermophysical properties of fluids (PROPATH). In this study, this method is applied to the investigation of cascade channel. Numerical results obtained by assuming supercritical pressure conditions indicate that the normal shock generated in the cascade channel deeply depends on the pressure condition. In particular, the speed of sound varying with the pressure variation at the supercritical state is a key thermophysical property which changes the flow field in the cascade channel. In addition, we also simulate those flows with nonequilibrium condensation in which the inlet pressure and temperature approaching to those of the critical point are specified. Then a nonequilibrium condensation model developed by our group is further applied to the numerical method. CO2 condensation observed in a case indicates that condensation occurs at a local region near the leading edge due to the flow expansion; the droplets soon grow at the local region and streams downward with keeping almost the same mass fraction.

  34. Unsteady Force on Multi-stage and Multi-passage Turbine Long Blade Rows Induced by Wet-steam Flows 査読有り

    Hironori Miyazawa, Takashi Furusawa, Satoru Yamamoto, Yasuhiro Sasao, Hiroharu Ooyama

    PROCEEDINGS OF THE ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2016, VOL 8 (GT2016-56360) 1-12 2016年

    出版者・発行元:AMER SOC MECHANICAL ENGINEERS

    DOI: 10.1115/GT2016-56360  

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    At the 2015 ASME Turbo Expo in Montreal, we presented a paper on unsteady three-dimensional wet-steam flow simulations for the last three stages of a low-pressure real steam turbine. We then focused on the investigation of unsteady wetness in the three-stage blade passages, which was conducted by assuming the same number of blades in the previous study and the real blade number. The obtained results showed that wetness is definitively influenced by the blade number difference between the stator and the rotor. This paper presents a numerical investigation of unsteady pressure forces on the multi-stage blade rows caused by stator-rotor interactions, which include unsteady wakes, vortices, shocks, and wetness. In particular, we investigate the effect of blade number variation on the pressure forces. Our results indicate that unsteady pressure forces are significantly influenced by shocks from the upstream stator trailing edges transferred to the adjacent rotor blade noses. We finally found that the unsteady pressure forces on the rotor blades are strongly influenced by shocks from upstream stator trailing edges near the hub region and the forces result in a time-dependent torque difference between neighboring two rotor blades.

  35. Unsteady Force of Wet-steam Flow on Multi-stage Turbine Long Blade Rows 査読有り

    Hironori Miyazawa, Toshiki Iwasaki, Satoshi Miyake, Takashi Furusawa, Satoru Yamamoto

    Proc. Int. Gas Turbine Congress 2015 Tokyo 1-7 2015年11月

  36. Numerical Simulation of Supercritical CO2 Flows in Transonic Turbine and Compressor 査読有り

    Takashi Furusawa, Hironori Miyazawa, Satoru Yamamoto

    Proc. Int. Gas Turbine Congress 2015 Tokyo 1-6 2015年11月

  37. A numerical method applied to forced and natural convection flows over arbitrary geometry 査読有り

    Shibo Qi, Takashi Furusawa, Satoru Yamamoto

    INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER 85 375-389 2015年6月

    出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD

    DOI: 10.1016/j.ijheatmasstransfer.2015.02.001  

    ISSN:0017-9310

    eISSN:1879-2189

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    In this study, a numerical method based on Cartesian mesh method and gridless approach applied to forced and natural convection flows over arbitrary geometry is proposed. In the proposed method, a preconditioning method developed by the authors has been coupled with the building-cube method, owing to its simplicity and efficiency in mesh generation, implementation of solution algorithm, and post-processing. A gridless approach is further introduced as a wall boundary treatment for its adaptability to complex physics and arbitrary geometry problems. In this study, first, two classical cases of steady forced convection flow past a circular cylinder and natural convection flow over a circular cylinder are tested; the advantages of the gridless approach over the immersed boundary method are clearly shown. Then, further tests of unsteady forced convection flow past two side-by-side circular cylinders and natural convection flow over a Y-shaped fin are also conducted, which show that the present numerical method is also qualified for flow problems involving complex physics and arbitrary geometries. In addition, computational cost comparisons show that the time cost increase caused by the introduction of the gridless approach is within 20% for all test cases considered. (C) 2015 Elsevier Ltd. All rights reserved.

  38. Thermophysical flow simulations of rapid expansion of supercritical solutions (RESS) 査読有り

    Satoru Yamamoto, Takashi Furusawa

    JOURNAL OF SUPERCRITICAL FLUIDS (Featured online on 'Advances in Engineering':https://advanceseng.com/general-engineering/thermophysical-flow-simulations-of-rapid-expansion-of-supercritical-solutions-ress/) 97 192-201 2015年2月

    出版者・発行元:ELSEVIER SCIENCE BV

    DOI: 10.1016/j.supflu.2014.11.016  

    ISSN:0896-8446

    eISSN:1872-8162

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    Thermophysical flows of rapid expansion of supercritical solutions (RESS) were numerically simulated from the nozzle inlet to the outlet of the expansion chamber. In these studies, supercritical carbon dioxide (SCO2) was used as the solvent, and naphthalene was used as the solute. Our approach seamlessly simulated SCO2 entering the nozzle, SCO2 crossing the critical pressure in the nozzle, CO2 gas expanding into the expansion chamber, and CO2 condensation in the chamber. The simulation is based on a preconditioning method developed by Yamamoto, together with mathematical models for thermophysical properties of substances in a program package for thermophysical properties of fluids (PROPATH). A primary issue was the extent to which changing the nozzle inlet and outlet pressures impacted the solubility of the solute. We also studied the effects of changing the nozzle throat diameter and throat length. In addition, we used a simple particle-formation model to predict nucleation, condensation, and coagulation of naphthalene particles. Our results indicate that the location at which the pressure crosses the critical pressure is sensitive to the pressure at the nozzle inlet, and nucleation of naphthalene starts near that location. (C) 2014 Elsevier B.V. All rights reserved.

  39. Numerical simulation of three-dimensional supercritical water flows in hydrothermal synthesis reactors with Arbitrary geometry 査読有り

    Takashi Furusawa, Shibo Qi, Satoru Yamamoto

    ASME/JSME/KSME 2015 Joint Fluids Engineering Conference, AJKFluids 2015 1A (AJK2015-03096) 1-7 2015年

    出版者・発行元:American Society of Mechanical Engineers

    DOI: 10.1115/AJKFluids2015-03096  

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    Numerical simulations of mixing flows of supercritical (SC) water and water liquid in a 3-D T-shaped circular pipe and a 3-D cross pipe are conducted using the numerical method developed by our group. The 3-D geometry is generated by Building-Cube Method (BCM) with the stepwise wall treatment. Numerical results of mixing flows in the two pipes are compared and the effect of the inlet temperature is evaluated. In the T-shaped circular reactor, the mixing is periodic and a vortex is observed at the mixing point. The mixing form certainly depends on the SC water temperature. In the counter flow reactor, the SC water flow becomes unsteady and is mixed with water liquid asymmetrically due to the rapid change of thermophysical properties and the buoyancy effect.

  40. Unsteady Wet-steam Flows through Low Pressure Turbine Final Three Stages considering Blade Number 査読有り

    Satoshi Miyake, Hironori Miyazawa, Satoru Yamamoto, Yasuhiro Sasao, Kazuhiro Momma, Hiroharu Ooyama, Toshihiro Miyawaki

    PROCEEDINGS OF THE ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2015, VOL 8 (GT2015-42366) 1-11 2015年

    出版者・発行元:AMER SOC MECHANICAL ENGINEERS

    DOI: 10.1115/GT2015-42366  

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    Unsteady three-dimensional wet-steam flows through stator rotor blade rows in the final three stages of a low-pressure steam turbine, taking the blade number into consideration, are numerically investigated. In ASME Turbo Expo 2014, we presented the numerical results of the unsteady flow assuming the same blade number. Here, this previous study is extended to flow simulations using the real blade number. The flows under three flow conditions, with and without condensation and considering the same and real blade numbers are simulated, and the numerical results are compared with each other and with the experimental results. Finally, the effect of the blade number on unsteady wet-steam flows in real low-pressure steam turbines is discussed.

  41. AERODYNAMIC AND STRUCTURAL NUMERICAL INVESTIGATION OF UNSTEADY FLOW EFFECTS ON LAST STAGE BLADES 査読有り

    Tadashi Tanuma, Hiroshi Okuda, Gaku Hashimoto, Satoru Yamamoto, Naoki Shibukawa, Kenichi Okuno, Hiroshi Saeki, Tomohiko Tsukuda

    PROCEEDINGS OF THE ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2015, VOL 8 (GT2015-43848) 1-13 2015年

    出版者・発行元:AMER SOC MECHANICAL ENGINEERS

    DOI: 10.1115/GT2015-43848  

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    The aim of this paper is to present some of research results of our current collaborative program to increase steam turbine efficiency with the development of high-performance blade and exhaust hood design methodology using large-scale aerodynamic and structural interaction analysis. Aerodynamic optimum designs of stator blades are already introduced in many designs of actual operating commercial steam turbine units. However, aerodynamic optimum designs of rotating blades are still difficult due to high centrifugal force and vibration stress on rotating blades. This paper focuses on rotating blades and exhaust diffusers that affect the flow field just downstream of last stage long blades. The large-scale high-accuracy CFD analysis of unsteady wet steam flows has been successfully introduced for simulations of low pressure exhaust diffuser using the Earth Simulator of Japan Agency for Marine-Earth Science and Technology. This result shows that the diffuser domain analysis can provide static pressure recovery coefficients and its circumferential deviations with enough accuracy for design use except correct location predictions of separations. The unsteady flow analyses of the typical designed last stage with the measured and calculated downstream static pressure distribution as the outlet boundary condition were conducted. The unsteady flow analyses of the typical designed low pressure exhaust diffuser with the measured and calculated upstream flow conditions as the inlet boundary condition were also conducted. Some of the calculated results were compared with measured data. The large-scale parallel computing Finite Element Analysis of turbine blades with inter-connection parts has been also successfully introduced on the Earth Simulator. The calculation result shows that the eigen frequencies of the present group of loosely-connected rotating blades correspond well to the existing measured data. For the next step, the unsteady structural analysis is being conducted with the calculated unsteady forces on the rotating blades as the FEA boundary conditions. Some of the FEA results are also presented in this paper.

  42. EFFECTS OF RETURN CHANNEL WITH SPLITTER VANES ON PERFORMANCE OF MULTISTAGE CENTRIFUGAL COMPRESSOR 査読有り

    Manabu Yagi, Takahiro Nishioka, Hiromi Kobayashi, Hideo Nishida, Satoru Yamamoto

    ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2015, VOL 2C (GT2015-43848) 1-10 2015年

    出版者・発行元:AMER SOC MECHANICAL ENGINEERS

    DOI: 10.1115/GT2015-42442  

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    The effects of a return channel with splitter vanes on the performance of a multistage centrifugal compressor were investigated. As a preliminary study, the optimum location of the splitter vanes was numerically examined with the aim of achieving high overall efficiency. The results indicated that the optimum location was the 30% of the normalized pitchwise distance from the suction side of the main vane, with the leading-edge located at a radius ratio to the main vane trailing edge of 1.77. To investigate the effects of the return channel with and without the optimum splitter vanes on the overall performance,, performance tests were carried out using a one and-half-stage test rig. Three pre-swirl vanes, whose vane angles from the tangential direction at the trailing-edge were 20, 30 and 40 were used to simulate three operating conditions with low, design and high flow coefficients, respectively. The design flow coefficient of the downstream impeller was 0.073 and the peripheral Mach number was 0.87. The test results showed that the return channel with the optimum splitter vanes achieved 11.8% higher overall efficiency at the high flow coefficient with respect to the case without the splitter vanes while maintaining the same efficiency at both low and design flow coefficients. The return channel with the optimum splitter vanes was concluded to be effective for improving the efficiency of a multistage centrifugal compressor.

  43. FPGA-based Custom Computing Architecture for Large-Scale Fluid Simulation with Building Cube Method 査読有り

    Kentaro Sano, Ryotaro Chiba, Tomoya Ueno, Hayato Suzuki, Ryo Ito, Satoru Yamamoto

    Computer Architecture News Special Issue for the proceedings of the International Symposium on Highly-Efficient Accelerators and Reconfigurable Technologies (HEART) 42 (4) 45-50 2014年9月1日

    DOI: 10.1145/2693714.2693723  

  44. A new matrix dissipation model for central scheme 査読有り

    Xinrong Su, Satoru Yamamoto

    INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS 74 (7) 494-513 2014年3月

    出版者・発行元:WILEY-BLACKWELL

    DOI: 10.1002/fld.3860  

    ISSN:0271-2091

    eISSN:1097-0363

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    In this paper, a simple and efficient improvement to the famous Swanson-Turkel matrix dissipation model for the central scheme is proposed. In the new matrix dissipation model, the accuracy is improved by eliminating the second-difference dissipation added to the characteristic fields representing the vorticity waves. This strategy is proposed based on analyzing the flow-physics about shock-vortex interaction using the Rankine-Hugoniot jump condition. In this paper, the behavior of central scheme for rotational flow is also theoretically and numerically analyzed. Results show a newfound problem of the original scalar and matrix dissipation models, in which for rotational flow excessive second-difference dissipation is added due to the pressure-based shock sensor. With current new matrix dissipation model improved accuracy is obtained at minimal cost overhead, especially, in the highly vortical region where the second-difference dissipation is reduced. At the same time, it preserves the excellent shock capturing capability and convergence speed of original method. Numerical properties of this new matrix dissipation model are validated with a series of numerical experiments and results comparison with original model verifies improved performance of current method. Copyright (c) 2013 John Wiley & Sons, Ltd.

  45. Multi-FPGA Accelerator for Scalable Stencil Computation with Constant Memory Bandwidth 査読有り

    Kentaro Sano, Yoshiaki Hatsuda, Satoru Yamamoto

    IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS 25 (3) 695-705 2014年3月

    出版者・発行元:IEEE COMPUTER SOC

    DOI: 10.1109/TPDS.2013.51  

    ISSN:1045-9219

    eISSN:1558-2183

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    Stencil computation is one of the important kernels in scientific computations. However, sustained performance is limited owing to restriction on memory bandwidth, especially on multicore microprocessors and graphics processing units (GPUs) because of their small operational intensity. In this paper, we present a custom computing machine (CCM), called a scalable streaming-array (SSA), for high-performance stencil computations with multiple field-programmable gate arrays (FPGAs). We design SSA based on a domain-specific programmable concept, where CCMs are programmable with the minimum functionality required for an algorithm domain. We employ a deep pipelining approach over successive iterations to achieve linear scalability for multiple devices with a constant memory bandwidth. Prototype implementation using nine FPGAs demonstrates good agreement with a performance model, and achieves 260 and 236 GFlop/s for 2D and 3D Jacobi computation, which are 87.4 and 83.9 percent of the peak, respectively, with a memory bandwidth of only 2.0 GB/s. We also evaluate the performance of SSA for state-of-the-art FPGAs.

  46. Numerical Simulation of Supercritical-fluid Flows over Arbitrary Geometry 査読有り

    Shibo Qi, Takashi Furusawa, Satoru Yamamoto

    Bulletin of JSME, Journal of Fluid Science and Technology 9 (1) 1-16 2014年

    DOI: 10.1299/jfst.2014jfst0008  

  47. NUMERICAL INVESTIGATION OF STEAM TURBINE EXHAUST DIFFUSER FLOWS AND THEIR THREE DIMENSIONAL INTERACTION EFFECTS ON LAST STAGE EFFICIENCIES 査読有り

    Tadashi Tanuma, Yasuhiro Sasao, Satoru Yamamoto, Yoshiki Niizeki, Naoki Shibukawa, Hiroshi Saeki

    PROCEEDINGS OF THE ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2014, VOL 1B (GT2014-26665) CD-ROM 2014年

    出版者・発行元:AMER SOC MECHANICAL ENGINEERS

    DOI: 10.1115/GT2014-26665  

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    The purpose of this paper is to present the methodology for high accurate aerodynamic numerical analysis and its design application of steam turbine down-flow type exhaust diffusers including their three dimensional flow interaction effects on last stage efficiencies. Down-flow type exhaust diffusers are used in large scale steam turbines from 200MW to 1400MW class units for power generation plants mainly. The axial length of typical 1000MW class large scale steam turbines is about 30-40m and its four low pressure (LP) down-flow type exhaust diffusers occupy a large amount of space. The axial lengths and diameters of these exhaust diffusers contribute significantly to the size, weight, cost, and efficiency of the turbine system. The aerodynamic loss of exhaust hoods is nearly the same as that of stator and rotor blading in LP steam turbines, and there remains scope for further enhancement of steam turbine efficiency by improving the design of LP exhaust hoods. In the design process of last stages, the average static pressure in the last stage exit is introduced accurately using numerical analysis and experimental data of model steam turbines and model diffusers. However the radial and circumferential unsteady aerodynamic interaction effects between last stages and their exhaust diffusers are still need to be investigated to increase the accuracy of the interaction effect on the last stage efficiencies. This paper presents numerical investigation of three dimensional wet steam flows including three dimensional flow interaction effects on last stage efficiencies in a down-flow type exhaust diffuser with non-uniform inlet flow from a typical last stage with long transonic blades designed with recent aerodynamic and mechanical design technology.

  48. Unsteady Wake and Vortex Interactions in 3-D Steam Turbine Low Pressure Final Three Stages 査読有り

    Satoshi Miyake, Itsuro Koda, Satoru Yamamoto, Yasuhiro Sasao, Kazuhiro Momma, Toshihiro Miyawaki, Hiroharu Ooyama

    PROCEEDINGS OF THE ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2014, VOL 1B (GT2014-25491) CD-ROM 2014年

    出版者・発行元:AMER SOC MECHANICAL ENGINEERS

    DOI: 10.1115/GT2014-25491  

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    A practical unsteady 3-D wet-steam flow through stator-rotor blade rows in a low-pressure steam turbine final three stages is numerically investigated. In ASME Turbo Expo 2013, we presented numerical results of unsteady 3-D wet-steam flows through three-stage stator-rotor low-aspect blade rows in a low-pressure steam turbine model designed by Mitsubishi Heavy Industry (Mal) assuming nonequilibrium condensation. The last study is extended to the final three stages with large aspect blade rows. The discussion in this paper is mainly focused on the effect of unsteady wake and vortex interactions on nonequilibrium condensation computed by our in-house code "Numerical Turbine System (NTS)". In addition, the NTS and the future perspective are also briefly introduced.

  49. Analysis of a meshless solver for high Reynolds number flow 査読有り

    Xinrong Su, Satoru Yamamoto, Kazuhiro Nakahashi

    INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS 72 (5) 505-527 2013年6月

    出版者・発行元:WILEY-BLACKWELL

    DOI: 10.1002/fld.3747  

    ISSN:0271-2091

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    In this paper, the extension of an upwind least-square based meshless solver to high Reynolds number flow is explored, and the properties of the meshless solver are analyzed both theoretically and numerically. Existing works have verified the meshless solver mostly with inviscid flows and low Reynolds number flows, and in this work, we are interested in the behavior of the meshless solver for high Reynolds number flow, especially in the near-wall region. With both theoretical and numerical analysis, the effects of two parameters on the meshless solver are identified. The first one is the misalignment effect caused by the significantly skewed supporting points, and it is found that the meshless solver still yields accurate prediction. It is a very interesting property and is opposite to the median-dual control volume based vertex-centered finite volume method, which is known to give degraded result with stretched triangular/tetrahedral cells in the near-wall region. The second parameter is the curvature, and according to theoretical analysis, it is found in the region with both large aspect ratio and curvature, and the streamwise residual is less affected; however, the wall-normal counterpart suffers from accuracy degradation. In this paper, an improved method that uses a meshless solver for the streamwise residual and finite difference for wall-normal residual is developed. This method is proved to be less sensitive to the curvature and provides improved accuracy. This work presents an understanding of the meshless solver for high Reynolds number flow computation, and the analysis in this paper is verified with a series of numerical experiments. Copyright (c) 2012 John Wiley & Sons, Ltd.

  50. Comparison of different wall boundary treatments for preconditioning method coupled with building-cube method 査読有り

    Shibo Qi, Takashi Furusawa, Satoru Yamamoto, Kazuhiro Nakahashi

    Procedia Engineering 61 298-305 2013年

    出版者・発行元:Elsevier Ltd

    DOI: 10.1016/j.proeng.2013.08.019  

    ISSN:1877-7058

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    Preconditioning method developed by the authors was coupled with Building-Cube Method (BCM). Wall boundary treatment is a critical issue for Building-Cube Method as a Cartesian mesh method. In the paper, the classical case, flow past a cycle cylinder at low Reynolds number is used, with three different boundary treatments tested: direct data transfer, staircase treatment and immersed boundary method (IBM). Also, two sets of numerical simulations with different number of grid points are conducted to assess the sensitivity of the three schemes to grid density. The numerical results of separation vortex length, pressure coefficient distribution and wall skin friction coefficient distribution are derived and compared with those existing experimental and numerical data sets. Comparison shows that immersed boundary method is a best choice of the three schemes, in both boundary orientation and pressure/velocity estimation. Moreover, immersed boundary method is also proved to be less sensitive to grid density than the other two, since the accuracy loss of immersed boundary method case with less grid points is much less. © 2013 The Authors.

  51. UNSTEADY FLOW EFFECT ON NONEQUILIBRIUM CONDENSATION IN 3-D LOW PRESSURE STEAM TURBINE STAGES 査読有り

    Satoshi Miyake, Satoru Yamamoto, Yasuhiro Sasao, Kazuhiro Momma, Toshihiro Miyawaki, Hiroharu Yama

    PROCEEDINGS OF THE ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2013, VOL 5B (GT2013-94832) 2013年

    出版者・発行元:AMER SOC MECHANICAL ENGINEERS

    DOI: 10.1115/GT2013-94832  

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    A numerical study simulating unsteady 3-D wet-steam flows through three-stage stator-rotor blade rows in a low-pressure steam turbine model experimentally conducted by Mitsubishi Heavy Industry (MET) was presented in the last ASME Turbo Expo by our group. In this study, the previous discussion is extended to the discussion how nonequilibrium condensation is influenced by unsteady wakes and corner vortices from prefaced multi-stage blade rows. Unsteady 3-D flows through three-stage stator-rotor blade rows are simulated assuming nonequilibrium condensation. Flows with a different inlet flow condition are calculated and the results are compared with each other. Instantaneous condensate mass fractions are visualized at different spans and cross sections in the three-stage stator and rotor blade rows. Also the time and space dependent values are plotted and the obtained unsteady flow characteristics are explained.

  52. EULERIAN-LAGRANGIAN NUMERICAL SIMULATION OF WET STEAM FLOW THROUGH MULTI-STAGE STEAM TURBINE 査読有り

    Yasuhiro Sasao, Satoshi Miyake, Kenji Okazaki, Satoru Yamamoto, Hiroharu Ooyama

    PROCEEDINGS OF THE ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2013, VOL 5B (GT2013-95945) 2013年

    出版者・発行元:AMER SOC MECHANICAL ENGINEERS

    DOI: 10.1115/GT2013-95945  

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    In this paper, we present an inclusive tracking algorithm for water droplets in a wet steam flow through a multi-stage steam turbine. This algorism is based on the Eulerian-Lagrangian coupled solver. The solver continuously computes water droplet growth, kinematic non-equilibrium between vapor and droplets, capture and kinetics of droplets on turbine blades, departure of large droplets from the trailing edge of blades, acceleration and atomization of large droplets, and recollisions between blades and droplets. Our Eulerian-Lagrangian coupled solver is used to predict wetness in unsteady three-dimensional (3D) wet steam flows through three-stage stator rotor cascade channels in a low pressure (LP) steam turbine model which is developed by Mitsubishi Heavy Industries (MITI). Droplet groups tracked by the discrete droplet model (DDM) are placed in the computational domain according to the predicted wetness. Interference from the gas phase on The droplets is considered, to track their kinetic and behavior, until they reach the outlet of the computational domain. The aim of this research is to investigate those multi-physics phenomena that trigger all forms of loss in steam turbines. In addition, this method will also be applied to multi-physics problems such as erosion in future work. This paper is presented as a first step in the research. Overviews of model of current coupling solver and several test calculations are presented.

  53. AERODYNAMIC INTERACTION EFFECTS FROM UPSTREAM AND DOWNSTREAM ON THE DOWN-FLOW TYPE EXHAUST DIFFUSER PERFORMANCE IN A LOW PRESSURE STEAM TURBINE 査読有り

    Tadashi Tanuma, Yasuhiro Sasao, Satoru Yamamoto, Yoshiki Niizeki, Naoki Shibukawa, Hiroshi Saeki

    PROCEEDINGS OF THE ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2013, VOL 5B (GT2013-95901) 2013年

    出版者・発行元:AMER SOC MECHANICAL ENGINEERS

    DOI: 10.1115/GT2013-95901  

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    The purpose of this paper is to explain aerodynamic interaction effects from upstream and downstream on the down-flow type exhaust diffuser performance in a low pressure steam turbine. To increase exhaust diffuser performance, design data related to the aerodynamic interaction effects from upstream turbine stages and downstream exhaust hood geometry on the exhaust diffuser performance would be very useful. This paper presents numerical investigation of three dimensional wet steam flows in a down-flow type exhaust diffuser with non-uniform inlet flow from a typical last stage with long transonic blades designed with recent aerodynamic and mechanical design technology. Previous studies show that small scale model tests and CFD analyses of exhaust diffusers with uniform inlet flow conditions are not enough to investigate diffuser efficiency and detail diffuser flow mechanism because inlet flow structures including tip leakage flows and blade wakes superimposed from a last stage and several other upstream turbine stages in low pressure turbines affect flow separations that reduce the exhaust diffuser performance. Recent studies by the authors show that the introduction of radial distributions of velocities and flow angles at the inlet section of exhaust diffuser measured in a full scale development steam turbine increased the accuracy of numerical analysis of diffuser flow. In the present study, the computational domain was enhanced and the method of boundary condition definition was improved to increase the accuracy of boundary layer separation and separation vortex generation in wet steam flows. Using the improved method, the calculation results explained the aerodynamic interaction effects from upstream and downstream on the down-flow type exhaust diffuser performance.

  54. On the accurate prediction of tip vortex: Effect of numerical schemes 査読有り

    Xinrong Su, Satoru Yamamoto, Xin Yuan

    Proceedings of the ASME Turbo Expo 6 (GT2013-94660) 2013年

    DOI: 10.1115/GT2013-94660  

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    This work is conducted towards the accurate prediction of compressor tip vortex. Accurate computation of highly vortical flow is affected by many parameters, such as numerical scheme and turbulence model. In this work the effect of numerical scheme is studied using mesh refinement study and comparison of numerical results from central scheme and a newly developed high order upwind scheme. Behaviors of numerical methods in the tip vortex region are also theoretically and numerically analyzed. It is found the computed tip vortex is significantly affected by mesh resolution and numerical dissipation. Currently widely numerical strategy, i.e., mesh with moderate resolution and low order scheme would yield quite inaccurate result. Predicted tip vortex is always dissipated earlier and this highlights the advantage of high order scheme in predicting detailed flow features. Besides coarser mesh and low order method, analysis of numerical methods reveals a new finding, in that the designed order of accuracy is not guaranteed in the tip vortex region. For central scheme pressure based shock sensor is unnecessarily activated and excessive artificial dissipation is added. For high order upwind scheme it tends to use low order reconstruction and new method considering flow physics shows its improved vortex prediction capability. Conclusions from this work can be used in future numerical studies about tip vortex to improve the numerical accuracy. © 2013 ASME.

  55. NUMERICAL INVESTIGATION OF EXHAUST DIFFUSER PERFORMANCES IN LOW PRESSURE TURBINE CASINGS 査読有り

    Tadashi Tanuma, Yasuhiro Sasao, Satoru Yamamoto, Shinji Takada, Yoshiki Niizeki, Naoki Shibukawa, Hiroshi Saeki

    PROCEEDINGS OF THE ASME TURBO EXPO 2011, VOL 7, PTS A-C (GT2011-45677) 2347-+ 2012年

    出版者・発行元:AMER SOC MECHANICAL ENGINEERS

    DOI: 10.1115/GT2011-45677  

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    Low pressure (LP) exhaust hoods are an important component of steam turbines. The aerodynamic loss of LP exhaust hoods is almost the same as those of the stator and rotor blading in LP steam turbines. Designing high performance LP exhaust hoods should lead further enhancement of steam turbine efficiency. This paper presents the results of exhaust hood computational fluid dynamics (CFD) analyses using last stage exit velocity distributions measured in a full-scale development steam turbine as the inlet boundary condition to improve the accuracy of the CFD analysis. One of the main difficulties in predicting the aerodynamic performance of the exhaust hoods is the unsteady boundary layer separation of exhaust hood diffusers. A highly accurate unsteady numerical analysis is introduced in order to simulate the diffuser flows in LP exhaust hoods. Compressible Navier-Stokes equations and mathematical models for nonequilibrium condensation are solved using the high-order high-resolution finite-difference method based on the fourth-order compact MUSCL TVD scheme, Roe's approximate Riemann solver, and the LU-SGS scheme. The SST turbulence model is also solved for evaluating the eddy viscosity. The computational results were validated using the measurement data, and the present CFD method was proven to be suitable as a useful tool for determining optimum three-dimensional designs of LP turbine exhaust diffusers.

  56. 前処理法とBCMに基づく熱対流の数値シミュレーション 査読有り

    古澤卓, 牧野幸太郎, 山本悟, 中橋和博

    日本機械学会論文集B編 78 (788) 745-752 2012年

    DOI: 10.1299/kikaib.78.745  

    ISSN:0387-5016

  57. 蒸気タービン部分流入段非定常流動解析によるフランジ形状の考察 査読有り

    高田真司, 笹尾泰洋, 山本悟, 田沼 唯士

    日本機械学会論文集B編 78 (788) 753-761 2012年

    DOI: 10.1299/kikaib.78.753  

    ISSN:0387-5016

  58. SIMULATION OF UNSTEADY 3-D WET-STEAM FLOWS THROUGH THREE-STAGE STATOR-ROTOR BLADE ROWS WITH EQUILIBRIUM AND NONEQUILIBRIUM CONDENSATIONS 査読有り

    Satoshi Miyake, Yasuhiro Sasao, Satoru Yamamoto, Soichiro Tabata, Toshihiro Miyawaki, Hiroharu Ooyama

    PROCEEDINGS OF THE ASME TURBO EXPO 2012, VOL 6 (GT2012-68828) 505-513 2012年

    出版者・発行元:AMER SOC MECHANICAL ENGINEERS

    DOI: 10.1115/GT2012-68828  

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    Unsteady 3-D wet-steam flows through three-stage statorrotor blade rows in a low-pressure steam turbine model developed by Mitsubishi Heavy Industry (MHI) are numerically investigated. In this study, a new and simple meshing strategy is introduced to improve the prediction of end-wall flows near the shroud and the hub. Dry and wet-steam conditions are taken into account and the calculated results changing the grid system are compared with the experiments. As a practical usage, coarse-grid computations using a PC cluster are also conducted and the results are compared with those using a fine grid and a supercomputer. In addition, a super-cooled condition is assumed and the computation is further conducted. Finally, the effect of homogeneous nucleation and the nonquilibrium condensation on the present flow is evaluated.

  59. NUMERICAL INVESTIGATION OF THREE-DIMENSIONAL WET STEAM FLOWS IN AN EXHAUST DIFFUSER WITH NON-UNIFORM INLET FLOWS FROM THE TURBINE STAGES IN A STEAM TURBINE 査読有り

    Tadashi Tanuma, Yasuhiro Sasao, Satoru Yamamoto, Yoshiki Niizeki, Naoki Shibukawa, Hiroshi Saeki

    PROCEEDINGS OF THE ASME TURBO EXPO 2012, VOL 6 (GT2012-69496) 589-602 2012年

    出版者・発行元:AMER SOC MECHANICAL ENGINEERS

    DOI: 10.1115/GT2012-69496  

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    The purpose of this paper is to present a numerical evaluation method for the aerodynamic design and development of high-efficiency exhaust diffusers in steam turbines, as well as to present the comparison between the numerical results and measured data in an actual real scale development steam turbine. This paper presents numerical investigation of three-dimensional wet steam flows in a down-flow-type exhaust diffuser that has non-uniform inlet flows from a typical last turbine stage. This stage has long transonic blades designed using recent aerodynamic and mechanical design technologies, including superimposed leakages and blade wakes from several upstream low pressure turbine stages. The present numerical flow analysis showed detail three-dimensional flow structures considering circumferential flow distributions caused by the down-flow exhaust hood geometry and the swirl velocity component from the last stage blades, including flow separations in the exhaust diffuser. The results were compared with experimental data measured in an actual development steam turbine. Consequently, the proposed aerodynamic evaluation method was proved to be sufficiently accurate for steam turbine exhaust diffuser aerodynamic designs.

  60. Simulation of Thermophysical Flow in Axisymmetric Nozzle with Expansion Chamber 査読有り

    Satoru Yamamoto, Ryo Matsuzawa, Takashi Furusawa

    AICHE JOURNAL 57 (10) 2629-2635 2011年10月

    出版者・発行元:WILEY-BLACKWELL

    DOI: 10.1002/aic.12482  

    ISSN:0001-1541

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    Axisymmetric nozzle flows with a free-jet expansion are simulated considering several substances and several flow conditions, and the thermophysical properties in the nozzle and the free-jet region are predicted. The present numerical method is based on the preconditioning method developed by Yamamoto and the mathematical models of thermophysical properties of the substances. As numerical examples show, gas flows of carbon dioxide, water, and nitrogen under a subcritical pressure condition are first calculated. Calculated distances to the Mach disk are compared with the experimental results, and also the density distributions are compared among these three substances. Second, carbon dioxide flows while changing the pressure from subcritical to supercritical values are calculated and the effect of pressure on the flow field is investigated. Third, flows of water vapor with and without nonequilibrium condensation are calculated and the effect of condensation on the flow field is investigated. (C) 2010 American Institute of Chemical Engineers AIChE J, 57: 2629-2635, 2011

  61. Domain-Specific Programmable Design of Scalable Streaming-Array for Power-Efficient Stencil Computation 査読有り

    Kentaro Sano, Yoshiaki Hatsuda, Satoru Yamamoto

    Computer Architecture News Special Issue for the proceedings of the International Workshop on Highly-Efficient Accelerators and Reconfigurable Technologies (HEART) to be published 2011年9月

    DOI: 10.1145/2082156.2082168  

  62. Supercritical-Fluid Flow Simulations Across Critical Point 査読有り

    Satoru Yamamoto, Takashi Furusawa, Ryo Matsuzawa

    COMPUTATIONAL FLUID DYNAMICS 2010 661-667 2011年

    出版者・発行元:SPRINGER-VERLAG BERLIN

    DOI: 10.1007/978-3-642-17884-9_84  

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    A numerical method for simulating supercritical-fluid flows across the critical point is introduced. The present numerical method is based on the preconditioning method developed by the authors and mathematical models of thermophysical properties developed by Kyushu University. The thermophysical properties such as density, viscosity, heat conductivity and the derived values are rapidly changed across the critical point. Especially the isobaric specific heat has a maximum peak value. The present method can simulate both low- and high-speed flows with the anomalous properties across the critical point accurately. As numerical examples, two different supercritical carbon-dioxide flows across the critical points are calculated and the calculated results are introduced.

  63. Numerical simulation of supercritical water in t-shaped channel across critical point 査読有り

    Takashi Furusawa, Satoru Yamamoto

    ASME-JSME-KSME 2011 Joint Fluids Engineering Conference, AJK 2011 1 (D) 1055-1060 2011年

    DOI: 10.1115/AJK2011-01005  

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    Mixing flows of supercritical fluid and liquid assuming the supercritical hydrothermal synthesis(SCHS) reactor are calculated using the numerical method developed by our group. First, the influence of thermophysical properties near the critical point to the flows is evaluated. The flows ignoring density change and specific heat change become a steady-state flow and are obviously different from flows considering all thermophysical properties. These results indicate that the large density difference in fluid at a narrow region caused by a peak of specific heat induces unsteady flows in the reactor. While higher bulk pressure results in a steady flow because of the moderate change of thermophysical properties. Next the flows in a sub channel changing the width are calculated. The channel with a smaller width makes a strong injection and the mixing occurs mainly at the downstream of the main channel. The tiled sub-channel may suppress the flow recirculation in the main channel. Copyright © 2011 by ASME.

  64. Numerical simulation of supercritical carbon dioxide flows across critical point 査読有り

    Satoru Yamamoto, Takashi Furusawa, Ryo Matsuzawa

    INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER 54 (4) 774-782 2011年1月

    出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD

    DOI: 10.1016/j.ijheatmasstransfer.2010.10.030  

    ISSN:0017-9310

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    Numerical study of supercritical carbon-dioxide flows across the critical point is presented. The present numerical method is based on the preconditioning method developed by Yamamoto and mathematical models of thermophysical properties for carbon dioxide programmed in the program package for thermophysical properties of fluids, developed by Kyushu University. First, the two-dimensional natural convection of carbon dioxide between two parallel plates is calculated while changing the bulk pressure. The calculated thermophysical properties of the carbon-dioxide flow under supercritical pressure are compared with those in a gas condition. Next, the natural convection of carbon dioxide in an O-shaped cyclic channel is calculated, and the effect of the density difference induced by the phase change to the flow is investigated. For application to high-speed flows, supercritical carbon dioxide flows through a nozzle with free-jet expansion (known as the process of rapid expansion of supercritical solutions) process are calculated. The calculated shock distance to the Mach disk generated in the free jet is compared with experiments and the density variations in the nozzle while changing the inlet temperature are numerically predicted. (C) 2010 Elsevier Ltd. All rights reserved.

  65. FPGA-Array with Bandwidth-Reduction Mechanism for Scalable and Power-Efficient Numerical Simulations Based on Finite Difference Methods 査読有り

    Kentaro Sano, Wang Luzhou, Yoshiaki Hatsuda, Takanori Iizuka, Satoru Yamamoto

    ACM TRANSACTIONS ON RECONFIGURABLE TECHNOLOGY AND SYSTEMS 3 (4) 2010年11月

    出版者・発行元:ASSOC COMPUTING MACHINERY

    DOI: 10.1145/1862648.1862651  

    ISSN:1936-7406

    eISSN:1936-7414

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    For scientific numerical simulation that requires a relatively high ratio of data access to computation, the scalability of memory bandwidth is the key to performance improvement, and therefore custom-computing machines (CCMs) are one of the promising approaches to provide bandwidth-aware structures tailored for individual applications. In this article, we propose a scalable FPGA-array with bandwidth-reduction mechanism (BRM) to implement high-performance and power-efficient CCMs for scientific simulations based on finite difference methods. With the FPGA-array, we construct a systolic computational-memory array (SCMA), which is given a minimum of programmability to provide flexibility and high productivity for various computing kernels and boundary computations. Since the systolic computational-memory architecture of SCMA provides scalability of both memory bandwidth and arithmetic performance according to the array size, we introduce a homogeneously partitioning approach to the SCMA so that it is extensible over a 1D or 2D array of FPGAs connected with a mesh network. To satisfy the bandwidth requirement of inter-FPGA communication, we propose BRM based on time-division multiplexing. BRM decreases the required number of communication channels between the adjacent FPGAs at the cost of delay cycles. We formulate the trade-off between bandwidth and delay of inter-FPGA data-transfer with BRM. To demonstrate feasibility and evaluate performance quantitatively, we design and implement the SCMA of 192 processing elements over two ALTERA Stratix II FPGAs. The implemented SCMA running at 106MHz has the peak performance of 40.7 GFlops in single precision. We demonstrate that the SCMA achieves the sustained performances of 32.8 to 35.7 GFlops for three benchmark computations with high utilization of computing units. The SCMA has complete scalability to the increasing number of FPGAs due to the highly localized computation and communication. In addition, we also demonstrate that the FPGA-based SCMA is power-efficient: it consumes 69% to 87% power and requires only 2.8% to 7.0% energy of those for the same computations performed by a 3.4-GHz Pentium4 processor. With software simulation, we show that BRM works effectively for benchmark computations, and therefore commercially available low-end FPGAs with relatively narrow I/O bandwidth can be utilized to construct a scalable FPGA-array.

  66. 相変化を伴う超臨界水熱合成の数値シミュレーション 査読有り

    古澤卓, 山本悟

    日本機械学会論文集B編 76 (765) 771-777 2010年

    出版者・発行元:None

    DOI: 10.1299/kikaib.76.765_771  

    ISSN:0387-5016

  67. Acceleration of Supercritical-fluid Flow Computation using an Accurate Look-up Table of Thermophysical Properties 査読有り

    Takashi Furusawa, Yasuhiro Sasao, Kentaro Sano, Satoru Yamamoto

    Proc. 8th Asian Computational Fluid Dynamics Conference CD-ROM 2010年

  68. NUMERICAL AND EXPERIMENTAL INVESTIGATIONS OF UNSTEAY 3-D WET-STEAM FLOWS THROUGH TWO-STAGE STATOR-ROTOR CASCADE CHANNELS 査読有り

    Satoru Yamamoto, Yasuhiro Sasao, Hiroto Kato, Hiroshi Satsuki, Hiroharu Ooyama, Kouichi Ishizaka

    PROCEEDINGS OF THE ASME TURBO EXPO 2010: TURBOMACHINERY: AXIAL FLOW FAN AND COMPRESSOR AERODYNAMICS DESIGN METHODS, AND CFD MODELING FOR TURBOMACHINERY, VOL 7, PTS A-C (GT2010-22796) 2257-2265 2010年

    出版者・発行元:AMER SOC MECHANICAL ENGINEERS

    DOI: 10.1115/GT2010-22796  

    詳細を見る 詳細を閉じる

    Unsteady 3-D flows through two-stage stator-rotor cascade channels in a low-pressure steam turbine model developed by Mitsubishi Heavy Industry(MHI) are numerically and experimentally investigated assuming dry and wet-steam conditions. The fundamental equations for condensate flows derived by the authors are applied to the present flow computations. The high-order high-resolution finite-difference method based on the fourth-order compact MUSCL TVD(Compact MUSCL) scheme and the Roe&apos;s approximate Riemann solver are used for the space discretization of convection terms. The pipelined LU-SGS scheme optimized for the parallel-implicit time-integration is also employed. MHI measured the total pressures, static pressures and yaw angles of flow velocity vectors at the outlet of first-stage rotor, second-stage stator, and second-stage rotor. The calculated results are compared with the experimental results. In addition, unsteady condensate mass fractions arc numerically visualized and the influence of wakes and secondary vortices to the condensation is discussed.

  69. Numerical method for near-critical fluids of arbitrary material 査読有り

    Satoru Yamamoto, Atsushi Ito

    Computational Fluid Dynamics 2006 - Proceedings of the Fourth International Conference on Computational Fluid Dynamics, ICCFD 2006 In press 795-800 2009年

    出版者・発行元:springer berlin

    DOI: 10.1007/978-3-540-92779-2-125  

  70. Numerical Prediction of Unsteady Flows through Whole Nozzle-Rotor Cascade Channels with Partical Admission 査読有り

    Yasuhiro Sasao, Kazuhiro Monma, Tadashi Tanuma, Satoru Yamamoto

    International Journal of Fluid Machinery and Systems 2 (3) 248-253 2009年

    出版者・発行元:Turbomachinery Society of Japan, Korean Fluid Machinery Association, Chinese Society of Engineering Thermophysics, IAHR

    DOI: 10.5293/IJFMS.2009.2.3.248  

    ISSN:1882-9554

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    This paper presents a numerical study for unsteady flows in a high-pressure steam turbine with a partial admission stage. Compressible Navier-Stokes equations are solved by the high-order high-resolution finite-difference method based on the fourth-order compact MUSCL TVD scheme, Roe's approximate Riemann solver, and the LU-SGS scheme. The SST-model is also solved for evaluating the eddy-viscosity. The unsteady two-dimensional flows through whole nozzle-rotor cascade channels considering a partial admission are numerically investigated. 108 nozzle passages with two blockages and 60 rotor passages are simultaneously calculated. The influence of the flange in the nozzle box to the lift of rotors is predicted. Also the efficiency of the partial admission stage changing the number of blockages and the number of nozzles is parametrically predicted.

  71. NUMERICAL AND EXPERIMENTAL INVESTIGATIONS OF UNSTEADY 3-D FLOW THROUGH TWO-STAGE CASCADES IN STEAM TURBINE MODEL 査読有り

    Yasuhiro Sasao, Hiroto Kato, Satoru Yamamoto, Hiroshi Satsuki, Hiroharu Ooyama, Kouichi Ishizaka

    PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON POWER ENGINEERING 2009 (ICOPE-09), VOL 2 (09-205) 479-484 2009年

    出版者・発行元:JAPAN SOC MECHANICAL ENGINEERS

    詳細を見る 詳細を閉じる

    Unsteady 3-D flows through two-stage stator-rotor cascade channels in a low-pressure steam turbine model developed by Mitsubishi Heavy Industry(MHI) are numerically investigated and compared with the experiments. The fundamental equations solved in this study are based on the compressible Navier-Stokes equation and the SST turbulence model in general curvilinear coordinates. The high-order high-resolution finite-difference method based on the fourth-order compact MUSCL TVD(Compact MUSCL) scheme and the Roe&apos;s approximate Riemann solver are used for the space discretization of convection terms. A parallelized LU-SGS scheme based on the pipelining algorithm is also employed for the parallel-implicit time-integration. Total pressures, static pressures and yaw angles of flow velocity vectors at the outlet of first-stage rotor, second-stage stator, and second-stage rotor obtained from the computation are compared with the corresponding experiments. Finally the reliability of both numerical and experimental approaches is discussed.

  72. 簡単なIB法による三次元任意形状物体周り流れの数値計算 査読有り

    水谷恒一郎, 山本悟

    日本機械学会論文集B編 74 (742) 1347-1353 2008年

    出版者・発行元:一般社団法人日本機械学会

    DOI: 10.1299/kikaib.74.1347  

    ISSN:0387-5016

    詳細を見る 詳細を閉じる

    A simple computational algorithm for solving flows over an arbitrary-shaped 3D geometry is proposed. This algorithm is based on the Immersed Boundary (IB) Method. A surface mesh for the object is generated by 3DCG software as a set of triangle polygons. A 3D Cartesian grid is used for the flow field. The velocity field near the object is modified by the present IB method along each grid line separately. In this paper, the present method is applied to an incompressible Navier-Stokes solver based on SMAC method using the staggered grid. Some practical flow problems assuming low Reynolds number are calculated and the results are compared with the experimental and the numerical results. Also, the present method is applied to flows over a moving object. Finally, the performance of the simple IB method applied to flows over 3D objects is discussed.

  73. 任意物質の圧縮性熱対流が計算できる数値解法 査読有り

    古澤卓, 山本悟

    日本機械学会論文集B編 74 (746) 2984-2090 2008年

    DOI: 10.1299/kikaib.74.2084  

  74. Parallel Computation of Condensate Flows through 2-D and 3-D Multistage Turbine Cascades 査読有り

    Satoru Yamamoto, Yasuhiro Sasao, Kentaro Sano, Hiroshi Satsuki, Kouichi Ishizaka, Hiroharu Ooyama

    Proc. International Gas Turbine Congress 2007 Tokyo CD-ROM 2007年12月

  75. Parallel-Implicit Computation of Three-dimensional Multistage Stator-Rotor Cascade Flows with Condensation 査読有り

    Satoru Yamamoto, Yasuhiro Sasao, Shoichiro Sato, Kentaro Sano

    Proc. 18th AIAA Computational Fluid Dynamics Conference (AIAA 2007-4460) 2007年6月

  76. A supercritical-fluids simulator applied to flows of arbitrary substance in arbitrary conditions 査読有り

    Satoru Yamamoto, Shinichi Yano, Akira Ishigame, Takashi Furusawa

    FEDSM 2007: PROCEEDINGS OF THE 5TH JOINT AMSE/JSME FLUIDS ENGINEERING SUMMER CONFERENCE VOL 1, PTS A AND B CD-ROM 69-74 2007年

    出版者・発行元:AMER SOC MECHANICAL ENGINEERS

    DOI: 10.1115/FEDSM2007-37154  

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    The supercritical-fluids simulator developed by our group is applied to the simulation of flows of arbitrary substance in arbitrary conditions. This simulator is based on the preconditioning method coupled with the PROPATH database. Since the database has the set of thermal properties for 48 substances, the present method can be applied to such substances. In this paper, substances such as carbon-dioxide, water, and nitrogen in several pressure and temperature conditions are calculated and the calculated results are compared with each other.

  77. A very simple immersed boundary method applied to three-dimensional incompressible Navier-Stokes solvers using staggered grid 査読有り

    Satoru Yamamoto, Koichiro Mizutani

    FEDSM 2007: PROCEEDINGS OF THE 5TH JOINT AMSE/JSME FLUIDS ENGINEERING SUMMER CONFERENCE VOL 1, PTS A AND B CD-ROM 63-68 2007年

    出版者・発行元:AMER SOC MECHANICAL ENGINEERS

    DOI: 10.1115/FEDSM2007-37153  

    詳細を見る 詳細を閉じる

    A very simple computational algorithm for solving flows over complex geometries is presented. This algorithm is based on a kind of the Immersed Boundary(IB) Methods. The complex 3D geometries are generated by the 3DCG software as a surface mesh of triangle polygons. A 3D Cartesian grid is used for the flow field. Only the points stuck with grid lines on triangle polygons are detected and flow velocities are modified using the points with the IB method. In this paper, this approach is applied to an incompressible Navier-Stokes solver based on the Simplified Marker and Cell(SMAC) method. Some practical flow problems assuming low Reynolds number are calculated and the results are compared with the experimental and the numerical results.

  78. Numerical and experimental predictions of heterogeneous condensate flow of moist air in cooled pipe 査読有り

    K Sakakura, S Yamamoto

    INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW 27 (2) 220-228 2006年4月

    出版者・発行元:ELSEVIER SCIENCE INC

    DOI: 10.1016/j.ijheatfluidflow.2005.08.006  

    ISSN:0142-727X

    eISSN:1879-2278

    詳細を見る 詳細を閉じる

    Condensate flows of moist air in a cooled pipe are numerically investigated by using the preconditioning method for solving incompressible and compressible Navier-Stokes equations with additional equations and source terms for condensate flows. The corresponding experiments are also conducted with the calculated results being compared with the experimental results. The present numerical method can apply not only to compresssible flows, but also to flows at a very low Mach number with condensation without the stiffness of solution. Very slow flows of moist air in a cooled pipe (in which the wall is partially cooled) are calculated using this method by assuming heterogeneous condensation. Then, humidity loss due to condensation when stream of moist air flow in the cooled pipe is numerically and experimentally predicted. (c) 2005 Elsevier Inc. All rights reserved.

  79. 多段タービン翼列を通る湿り蒸気流れの数値シミュレーション 査読有り

    笹尾泰洋, 山本悟, 石坂浩一, 大山宏治

    日本機械学会論文集B編 73 (728) 2006年4月

    DOI: 10.1299/kikaib.73.936  

  80. Preconditioning method for compressible near-critical fluids in micro-channel 査読有り

    Satoru Yamamoto

    Computational Fluid Dynamics 2004, Proceedings 517-522 2006年

    出版者・発行元:SPRINGER-VERLAG BERLIN

  81. ターボ機械多段翼列を通る非定常三次元湿り蒸気流れの大規模並列計算

    笹尾泰洋, 山本悟

    SENAC 39 (3) 33-42 2006年

  82. Systolic computational-memory architecture for an FPGA-based flow solver 査読有り

    Kentaro Sano, Takanori Iizuka, Satoru Yamamoto

    IEEE MWSCAS'06: PROCEEDINGS OF THE 2006 49TH MIDWEST SYMPOSIUM ON CIRCUITS AND SYSTEMS, 423-+ 2006年

    出版者・発行元:IEEE

    DOI: 10.1109/MWSCAS.2006.382089  

    ISSN:1548-3746

    詳細を見る 詳細を閉じる

    This paper presents an FPGA-based flow solver based on the systolic computational-memory architecture. We show that the flow solver based on the fractional-step method with difference schemes can be expressed as a systolic algorithm, and the systolic computational-memory architecture is suitable to design the special-purpose processor for the flow solver. Based on this architecture, we propose a specialpurpose processor comprised of a 2D array of cells connected by a 2D mesh network. Each cell has a computational data-path and a local memory. While the whole array stores data as a memory, it also performs highly parallel and scalable floating-point computations with the sufficient memory bandwidth. We report the initial design of the processor for two ALTERA Stratix II FPGAs, and discuss its estimated peak performance that could reach 30 GFLOPS at only 60MHz.

  83. Numerical Investigation of Condensation and Turbulence in Turbine Stator-rotor Interaction 査読有り

    Yasuhiro SASAO, Satoru YAMAMOTO, Tadashi TANUMA

    Proceedings of 2005 Asian Congress on Gas Turbine CD-ROM 2005年11月

  84. Preconditioning method applied to near-critical carbon-dioxide flows in micro-channel 査読有り

    S Yamamoto, M Toratani, Y Sasao

    JSME INTERNATIONAL JOURNAL SERIES B-FLUIDS AND THERMAL ENGINEERING 48 (3) 532-539 2005年8月

    出版者・発行元:JAPAN SOC MECHANICAL ENGINEERS

    DOI: 10.1299/jsmeb.48.532  

    ISSN:1340-8054

    詳細を見る 詳細を閉じる

    A numerical method for simulating near-critical carbon-dioxide flows in a micro-channel is presented. This method is based on the preconditioning method applied to the compressible Navier-Stokes equations. The Peng-Robinson equation of state is introduced to evaluate the properties of near-critical fluids. As numerical examples, Near-critical carbon-dioxide flows in a square cavity and in a micro-channel are calculated and the calculated results are compared with the experimental data and the theoretical results. Finally, we demonstrate that the compressibility dominates the near-critical carbon-dioxide flows in a micro-channel even if the flow is very slow and the Reynolds number is very low.

  85. Preconditioning method for condensate fluid and solid coupling problems in general curvilinear coordinates 査読有り

    S Yamamoto

    JOURNAL OF COMPUTATIONAL PHYSICS 207 (1) 240-260 2005年7月

    出版者・発行元:ACADEMIC PRESS INC ELSEVIER SCIENCE

    DOI: 10.1016/j.jcp.2005.01.013  

    ISSN:0021-9991

    詳細を見る 詳細を閉じる

    A preconditioned flux-vector splitting (PFVS) scheme in general curvilinear coordinates which can be applied to condensate fluid and solid coupling problems is presented and some typical calculated results are shown to prove the availability of the present method. This method is based on the preconditioning method applied to compressible Navier-Stokes (NS) equations with additional equations and source terms for condensate flows. Since the present PFVS terms composed of the convective and pressure terms of the NS equations are completely reduced to only the pressure terms when the velocities are set to zero, the present scheme can further applied to the calculation not only for a dynamic field but also for a static field including a transitional field from the dynamic region to the static region. In this paper, as a first stage of the present study, coupling problems between a condensate flow in a flow field and heat conduction in a solid structure are simultaneously calculated by using the present method. As numerical examples, transonic and low speed flows around the NACA0012 airfoil, nonequilibrium condensate flows in a nozzle, and natural convection with condensation around a pipe at 1g and zero gravity are simulated with heat conduction in the solid structure. &COPY; 2005 Elsevier Inc. All rights reserved.

  86. Numerical Analysis of Combined free and Forced Convection of Fluids with Condensate in Parallel Plate Channels 査読有り

    Kei Sakakura, Yasuhiro Sasao, Satoru Yamamoto

    Proceedings of the Sixth KSME-JSME Thermal and Fluids Engineering Conference CD-ROM 2005年3月

  87. Numerical Investigation of Condensate Turbulent Flows in Turbomachinery 査読有り

    Yasuhiro Sasao, Satoru Yamamoto

    Proceedings of the Sixth KSME-JSME Thermal and Fluids Engineering Conference CD-ROM 2005年3月

  88. Computation of practical flow problems with release of latent heat 査読有り

    S Yamamoto

    ENERGY 30 (2-4) 197-208 2005年2月

    出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD

    DOI: 10.1016/j.energy.2004.04.041  

    ISSN:0360-5442

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    Practical flow problems with condensation due to phase change from water vapor to water liquid are numerically investigated. Fundamental equations solved in this study consist of conservation laws of mixed gas, water vapor, water liquid, and the number density of water droplets. coupled with the momentum equations and the energy equation. The classical condensation theory is employed for modeling homogeneous nucleation and nonequilibrium condensation. Heterogeneous nucleation is approximately modeled by assuming a constant radius and a constant number density of droplets. These equations are solved by a high-order high-resolution finite-difference method. As external flows. condensate transonic flows around NACA0012 airfoil in atmospheric flow conditions are calculated. and as internal flows, steady and unsteady transonic wet-steam flows through a steam turbine cascade channel are also calculated. (C) 2004 Elsevier Ltd. All rights reserved.

  89. A Preconditioning Method for Two-Phase Flows with Cavitation 査読有り

    Byeong Rog SHIN, Satoru YAMAMOTO

    Computational Fluid Dynamics JOURNAL 13 (4) 722-729 2005年1月

  90. Preconditioning method for very-slow flows with heterogeneous condensation in a mixing T-junction channel 査読有り

    Kei Sakakura, Yasuhiro Sasao, Satoru Yamamoto

    Proceedings of the ASME Fluids Engineering Division Summer Conference - 2005, Vol 1, Pts A and B (FEDSM2005-77073) 1025-1032 2005年

    出版者・発行元:AMER SOC MECHANICAL ENGINEERS

    DOI: 10.1115/FEDSM2005-77073  

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    The purpose of this study is to develop a numerical method for simulating condensate flow problems observed in industrial processes. The preconditioning method developed by our group is applied to the calculations of very-slow flows assuming heterogeneous condensation in a mixing T-junction channel in which dry and moist air streams flowing into the channel are mixed together. A classical condensation model simplified by our group is used for evaluating condensation with heterogeneous nucleation. As shown in the calculated results, condensation in a T-junction pipe was variously influenced by the mixing type, such as stratified, turned jet, and wall jet flows. A notable difference in temperature distributions was also found with and without condensation due to the release of latent heat when condensation occurs.

  91. Numerical prediction of unsteady flows through turbine stator-rotor channels with condensation 査読有り

    Yasuhiro Sasao, Satoru Yamamoto

    Proceedings of the ASME Fluids Engineering Division Summer Conference - 2005, Vol 1, Pts A and B (FEDSM2005-77205) 855-861 2005年

    出版者・発行元:AMER SOC MECHANICAL ENGINEERS

    DOI: 10.1115/FEDSM2005-77205  

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    Unsteady transonic flows with condensation through steam turbine stator-rotor channels are numerically predicted by using the numerical method developed by our group. Fundamental equations solved here consist of conservation laws of mixed gas, water vapor, water liquid, and the number density of water droplets, coupled with the momentum equations and the energy equation. Also the shear-stress transport (SST) turbulence model is employed to predict the turbulent quantities. The numerical method is based on the high-order high-resolution finite-difference method. The fourth-order monotone upstream-centered schemes for conservation laws (MUSCL) with the total variation diminishing (TVD) scheme, Roe's approximate Riemann solver, and the lower-upper symmetric Gauss-Seidel (LU-SGS) scheme are employed in the numerical method. As numerical examples, transonic condensate flows of moist air through a turbine and a compressor cascade channel are first calculated. Also wet-steam turbine stator-rotor cascade channels are calculated assuming homogeneous and heterogeneous condensations.

  92. 二次元自然対流問題による前処理型陰的流束分離スキ-ムの検証 査読有り

    坂倉圭, 山本悟

    日本機械学会論文集B編 71 (709) 2213-2217 2005年

    出版者・発行元:None

    DOI: 10.1299/kikaib.71.2213  

    ISSN:0387-5016

  93. A numerical method for natural convection and heat conduction around and in a horizontal circular pipe 査読有り

    S Yamamoto, D Niiyama, BR Shin

    INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER 47 (26) 5781-5792 2004年12月

    出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD

    DOI: 10.1016/j.ijheatmasstransfer.2004.06.039  

    ISSN:0017-9310

    詳細を見る 詳細を閉じる

    Natural convection around a horizontal circular pipe coupled with heat conduction in the solid structure is numerically investigated using a preconditioning method for solving incompressible and compressible Navier-Stokes equations. In this method, fundamental equations are completely reduced to an equation of heat conduction when the flow field is static (zero velocity). Therefore, not only compressible flows but also very slow flows such as natural convection in a flow field and heat conduction in a static field can be simultaneously calculated using the same computational algorithm. In this study, we first calculated the compressible flow around a NACA0012 airfoil with conduction in the airfoil and then simulated natural convections around a horizontal circular pipe with a different heat conductivity. Finally, we numerically investigated the effect of heat conductivity of the pipe on natural convection. (C) 2004 Elsevier Ltd. All rights reserved.

  94. Overrelaxation applied to lower-upper symmetric Gauss-Seidel method for hypersonic flows 査読有り

    S Yamamoto, D Sato

    AIAA JOURNAL 42 (9) 1849-1853 2004年9月

    出版者・発行元:AMER INST AERONAUT ASTRONAUT

    ISSN:0001-1452

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    An implicit time-marching method for acceleration of the convergence of solution for the compressible Navier-Stokes equations is presented. This is based on the lower-upper symmetric-Gauss-Seidel (LU-SGS) method proposed by Yoon and Jameson (Yoon, S., and Jameson, A., "Lower-Upper Symmetric-Wuss-Seidel Method for the Eider and Navier-Stokes Equations," AIAA Journal, Vol. 26, 1988, pp. 1025-1026). A very simple overrelaxation is additionally executed in the LU-SGS method coupled with diagonal flux splitting. Then, an overrelaxation parameter omega, a parameter similar to that in the well-known successive-overrelaxation method is introduced. The calculated results for a hypersonic viscous flows around a cylinder and through a compression corner indicate that the convergence is accelerated by a proper value of omega(1 &lt; omega &lt; 2). This method is also applied to a hypersonic thermochemical nonequilibrium flow around a sphere.

  95. Application of preconditioning method to gas-liquid two-phase flow computations 査読有り

    BR Shin, S Yamamoto, Y Xin

    JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME 126 (4) 605-612 2004年7月

    出版者・発行元:ASME

    DOI: 10.1115/1.1777230  

    ISSN:0098-2202

    eISSN:1528-901X

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    A preconditioned numerical method for gas-liquid two-phase flows is applied to solve cavitating flow. The present method employs a finite-difference method of the dual time-stepping integration procedure and Roe's flux difference splitting approximation with the MUSCL-TVD scheme. A homogeneous equilibrium cavitation model is used. The present density-based numerical method permits simple treatment of the whole gas-liquid two-phase flow field, including wave propagation, large density changes and incompressible flow characteristics at low Mach number. Two-dimensional internal flows through a backward-facing step duct, convergent-divergent nozzles and decelerating cascades are computed using this method.. Comparisons of predicted and experimental results are provided and discussed.

  96. Application of preconditioning method to gas-liquid two-phase flow computations 査読有り

    BR Shin, S Yamamoto, Y Xin

    JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME 126 (4) 605-612 2004年7月

    出版者・発行元:ASME

    DOI: 10.1115/1.1777230  

    ISSN:0098-2202

    eISSN:1528-901X

    詳細を見る 詳細を閉じる

    A preconditioned numerical method for gas-liquid two-phase flows is applied to solve cavitating flow. The present method employs a finite-difference method of the dual time-stepping integration procedure and Roe's flux difference splitting approximation with the MUSCL-TVD scheme. A homogeneous equilibrium cavitation model is used. The present density-based numerical method permits simple treatment of the whole gas-liquid two-phase flow field, including wave propagation, large density changes and incompressible flow characteristics at low Mach number. Two-dimensional internal flows through a backward-facing step duct, convergent-divergent nozzles and decelerating cascades are computed using this method.. Comparisons of predicted and experimental results are provided and discussed.

  97. PRECONDITIONED FLUX-SPLITTING METHOD FOR CONDENSATE FLOWS AND NEAR-CRITICAL FLUIDS 招待有り 査読有り

    Satoru Yamamoto, Byeong Rog Shin

    Proceedings of ECCOMAS2004-Jyvaskyla CD-ROM 2004年7月

  98. Numerical Prediction of Humid Effect to Transonic Flows in Turbomachinery 査読有り

    Yasuhiro SASAO, Satoru YAMAMOTO

    Proceedings of International Gas Turbine Congress 2003 Tokyo I CD-ROM 2003年11月

  99. A Numerical Method for Gravitational Condensate Flows with Structure 査読有り

    Satoru YAMAMOTO, Daisuke NIIYAMA, Byeong Rog SHIN

    Proceedings of the 5th Asian Computational Fluid Dynamics I CD-ROM 2003年10月

  100. Onset of condensation in vortical flow over sharp-edged delta wing 査読有り

    S Yamamoto

    AIAA JOURNAL 41 (9) 1832-1835 2003年9月

    出版者・発行元:AMER INST AERONAUT ASTRONAUT

    ISSN:0001-1452

  101. PRECONDITIONED HIGH-RESOLUTION SCHEME FOR GRAVITATIONAL FLOWS WITH CONDENSATION 査読有り

    Satoru YAMAMOTO, Daisuke NIIYAMA, Byeong-Rog SHIN

    Proceedings of FEDSM’03, 4th ASME_JSME Joint Fluids Engineering Conference FEDSM2003-45390 CD-ROM 2003年7月

  102. Preconditioned implicit flux-splitting scheme for condensate flows 査読有り

    S Yamamoto, BR Shin

    COMPUTATIONAL FLUID DYNAMICS 2002 I 112-117 2003年

    出版者・発行元:SPRINGER-VERLAG BERLIN

    詳細を見る 詳細を閉じる

    A numerical method for simulating high- and very low-speed condensate flows in atmospheric flow conditions is proposed. This is based on the preconditioning method, Roe's scheme, the 4th-order compact MUSCL scheme, and the LU-SGS scheme. A preconditioned implicit flux-splitting form is newly derived. This form is easily applied to the Roe scheme and the LU-SGS scheme. Condensate flows around the NACA0012 and a cylinder in several atmospheric flow conditions are calculated using the present preconditioned implicit scheme.

  103. 前処理型陰的流束分離スキームとその熱対流問題への応用 査読有り

    山本悟, 新山大輔, 申 炳録

    日本機械学会論文集B編 69 (678) 274-279 2003年

    出版者・発行元:None

    DOI: 10.1299/kikaib.69.274  

    ISSN:0387-5016

  104. Numerical Method of Steady and Unsteady Compressible Interdisciplinary Flow Problems 招待有り 査読有り

    Satoru Yamamoto

    Computational Fluid Dynamics JOURNAL 11 234-241 2002年7月

  105. Numerical investigation of supersonic MPD viscous flows with ionization 査読有り

    Hironori Takeda, Satoru Yamamoto

    JSME International Journal, Series B: Fluids and Thermal Engineering 45 (1) 97-101 2002年2月

    DOI: 10.1299/jsmeb.45.97  

    ISSN:1340-8054

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    An implicit time-marching method based on the LU-SGS scheme developed for self-filed magneto-plasma dynamic (MPD) fully-ionized viscous flows is extended to the method for self-filed MPD viscous flows considering a finite rate of ionization. The axisymmetric compressible Navier-Stokes equations with Lorentz force and Joule heating, the equation of magnetic induction induced from Maxwell's equations with Ohm's law, and the continuity equation of electron are simultaneously solved using the present time-marching method. Partially ionized flows in an experimental MPD thruster are simulated and compared with the experiments. Also the effect of flow conditions such as the inlet temperature, the total current, and the rate of ionization to the flow field is numerically investigated.

  106. Implicit time-marching solution of partially ionized flows in self-field MPD thruster 査読有り

    H Takeda, S Yamamoto

    TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES 44 (146) 223-228 2002年2月

    出版者・発行元:JAPAN SOC AERONAUT SPACE SCI

    DOI: 10.2322/tjsass.44.223  

    ISSN:0549-3811

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    Self-filed magneto-plasma dynamic (MPD) viscous flows are numerically investigated. The axisymmetric compressible Navier-Stokes equations with the Lorentz force and Joule heating, the equation of magnetic induction derived from Maxwell's equations with Ohm's law, and the continuity equation of electrons are simultaneously solved with the use of an implicit time-marching method based on the LU-SGS scheme. Partially ionized flows in the experimental MPD thruster are simulated and compared with the experimental results. The calculated current stream lines and the pressure of the cathode tip are found to agree well with the experiments. The values of the pressure of the cathode tip and the thrust are also numerically predicted by changing the distance from the cathode tip to the anode.

  107. 大気環境中における遷音速翼周り流れの数値シミュレーション 査読有り

    佐藤大悟, 山本悟

    日本機械学会論文集B編 68 (671) 1905-1910 2002年

    出版者・発行元:None

    DOI: 10.1299/kikaib.68.1905  

    ISSN:0387-5016

  108. Onset of Condensation in Vortical Flow over Sharp-edged Delta Wing 査読有り

    Satoru Yamamoto

    Proc. of 15th AIAA Computational Fluid Dynamics CD-ROM 1-10 2001年6月

  109. Time-marching method for complicated compressible flow equations with source term 査読有り

    S Yamamoto

    COMPUTATIONAL FLUID DYNAMICS 2000 133-138 2001年

    出版者・発行元:SPRINGER-VERLAG BERLIN

  110. Numerical Study of Unsteady 3D Hypersonic Shock Interference Flows 査読有り

    Satoru Yamamoto

    Computational Fluid Dynamics JOURNAL Special Number 766-770 2001年

  111. Flow Characteristics of Unsteady Three-dimensional Type IV Shock Interference 査読有り

    Satoru YAMAMOTO, Hiroshi TERASHIMA

    Preprint of Fluids 2000, AIAA Paper 2000-2690 1-7 2000年6月

  112. Numerical simulation of condensation around the 3-D wing 査読有り

    S Yamamoto, H Hagari, M Murayama

    TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES 42 (138) 182-189 2000年2月

    出版者・発行元:JAPAN SOC AERONAUT SPACE SCI

    ISSN:0549-3811

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    Nonequilibrium condensation generating around 2-D and 3-D transonic wings in moist air is numerically studied. The fundamental equations of the compressible Navier-Stokes equations and the model equations for the phase change based on the classical condensation theory assuming homogeneous nucleation are solved using the fourth-order compact MUSCL TVD scheme and the explicit second-order Runge-Kutta scheme. As numerical examples, 2-D transonic viscous flows around the RAE2822 airfoil and 3-D transonic viscous flows around the ONERA M6 wing under atmospheric wind tunnel conditions are calculated changing the relative humidity, and the calculated results are compared with those of 0% humidity and the experiments. The calculated results show that nonequilibrium condensation induces the release of latent heat and it directly affects the pressure coefficient distributions on the airfoil surface by increasing the relative humidity. Therefore, wing performance is influenced by the condensation. Finally, the reliability and limitations of the present method are discussed.

  113. MPDスラスタ-粘性流れの高効率陰的差分解法 査読有り

    山本悟, 千葉史人

    日本機械学会論文集B偏 66 (643) 647-654 2000年

    出版者・発行元:None

    DOI: 10.1299/kikaib.66.647  

    ISSN:0387-5016

  114. Numerical investigation shock/vortex interaction in hypersonic thermochemical nonequilibrium flow 査読有り

    S Yamamoto, N Takasu, H Nagatomo

    JOURNAL OF SPACECRAFT AND ROCKETS 36 (2) 240-246 1999年3月

    出版者・発行元:AMER INST AERONAUT ASTRONAUT

    ISSN:0022-4650

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    A numerical investigation of unsteady hypersonic shock/shock interference flows classified by Edney (Edney, B. E., "Anomalous Heat Transfer and Pressure Distributions on Blunt Bodies at Hypersonic Speeds in the Presence of an Impinging Shock," Aeronautical Research Inst, of Sweden, FFA Rept. 115, Stockholm, Sweden, Feb. 1968) considering the thermochemical nonequilibrium effect is presented. The numerical method used is composed of the fourth-order compact MUSCL total variational diminishing scheme, the maximum second-order lower-upper symmetric Gauss-Seidel scheme, and the advection upstream splitting method scheme for capturing shocks and vortices accurately. The two-temperature model based on the Park model (Park, C., "Two-Temperature Interpretation of Dissociation Rate Data for N-2 and O-2:" AIAA Paper 88-0458, Jan. 1988) has taken the thermochemical nonequilibrium into consideration. The nitrogen hows under several flow conditions are calculated. The obtained results show that the type of the shock/shock interference is strongly dependent on the location of the impinging shock as well as the shock standoff distance. Finally, unsteady flow characteristics associated with the thermochemical nonequilibrium effect, especially very complicated flow structures involving shocks, compression waves, vortices, and their interactions, are investigated and explained.

  115. Shock-Vortex Capturing Method and it's Application to Unsteady 3-D Cascade Flow 査読有り

    Satoru Yamamoto

    Computational Fluid Dynamics JOURNAL 8 (2) 341-349 1999年

  116. Numerical Study of Unsteady Gas and Steam Turbine Cascade Flows 査読有り

    Satoru Yamamoto, Tadashi Tanuma

    Proc. of Int. Gas Turbine Congress 1999 Kobe I 489-496 1999年

  117. 飛行機雲の数値シミュレ-ション 査読有り

    山本 悟, 葉狩 秀樹, 村山 光宏

    日本航空宇宙学会論文集 47 (540) 41-46 1999年1月

    出版者・発行元:一般社団法人 日本航空宇宙学会

    DOI: 10.2322/jjsass.47.41  

    ISSN:1344-6460

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    The nonequilibrium condensation generating around the 2-D and 3-D wings in moist air, so-called 'Vapor Trail, ' is numerically investigated. The fundamental equations composed of the compressible Navier-Stokes equations and tho model equations for the phase change based on the classical condensation theory are solved using the fourth-order accurate compact MUSCL TVD scheme and the second-order Runge-Kutta scheme. As numerical examples, the 2-D transonic viscous flows around the RAE 2822 wing in moist air are calculated changing the relative humidity and the calculated results are compared with those in dry air and the experiment. Also the 3-D flows around the ONERA M 6 wing in moist air are preliminary calculated.

  118. 非定常三次元遷音速ガスタ-ビン翼列流れの数値解析 査読有り

    山本 悟, 白石 隆

    日本機械学会論文集(B編) 64 (624) 2424-2430 1998年8月

    DOI: 10.1299/kikaib.64.2424  

  119. An efficient CFD approach for simulating unsteady hypersonic shock-shock interference flows 査読有り

    S Yamamoto, S Kano, H Daiguji

    COMPUTERS & FLUIDS 27 (5-6) 571-580 1998年6月

    出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD

    DOI: 10.1016/S0045-7930(97)00061-3  

    ISSN:0045-7930

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    An efficient CFD approach based on higher order accurate numerical schemes has been developed for simulating unsteady hypersonic viscous flows strongly associated with shock-shock interference flow phenomena. The principal concept of the present approach is to employ the higher-resolution finite difference schemes based on the fourth-order accurate compact MUSCL TVD scheme coupled with the AUSM-based scheme in space discretization and based on the maximum second-order accurate LU-SGS scheme modified using the Newton iteration in time integration. The hypersonic shock-shock interference flow which is well known as the Type TV is numerically investigated. The obtained numerical results are showing extremely complicated flow structures, such as an unsteady supersonic jet, a jet-bow-shock, and unsteady supersonic shear layers. The reliability of the calculated results is checked by comparison with the existing experimental and numerical results. (C) 1998 Elsevier Science Ltd. All rights reserved.

  120. Numerical study of unsteady shock/boundary-layer interaction induced by a blunt fin 査読有り

    Satoru Yamamoto, Norinao Takasu

    29th AIAA Fluid Dynamics Conference 1-9 1998年

    出版者・発行元:American Institute of Aeronautics and Astronautics Inc.

    DOI: 10.2514/6.1998-2815  

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    Unsteady three-dimensional shock/turbulent boundary layer separations induced by a hemicylindrically blunted fin normal to the flat plate considering the sweepback angle are numerically studied. It is known by previous experimental studies that those flows become unsteady. However, unsteady flow characteristics dominating them have not been captured sufficiently by previous numerical studies yet. In the present study, the higher-resolution finite-difference method based on the fourth-order compact MUSCL TVD scheme with the modified AUSM and the maximum second-order LUSGS scheme are employed to get unsteady flows associated with the shock/turbulent boundary layer interaction and shock/shock interference between the separation shock and the bow shock. In the calculated results of the unswept fin, unsteady multiple supersonic jets are produced by the interaction between multiple separation shocks and the bow shock. A large-scale supersonic jet induced by multiple jets streams into separation bubbles. The number of bubbles is changed according to the strength and the direction of the jet. Each bubble generates a separation shock. Therefore, a system of multiple separation shocks is formed again. Finally, this cyclic system makes the present flow unsteady and intermittent. The cases of the swept fin are also calculated. The reduction of the separation length and the stabilization of the unsteadiness can be explained by the strength of the cyclic system.

  121. Numerical investigation of nonequilibrium condensation effect around 3-D transonic wing in moist air 査読有り

    S Yamamoto, H Hagari

    SIXTEENTH INTERNATIONAL CONFERENCE ON NUMERICAL METHODS IN FLUID DYNAMICS 515 554-559 1998年

    出版者・発行元:SPRINGER-VERLAG BERLIN

    ISSN:0075-8450

  122. ガスタ-ビン冷却静翼の空力特性 査読有り

    渋谷 直紀, 川崎 榮, 田沼 唯士, 山本 悟

    日本ガスタービン学会誌 25 (99) 70-75 1997年12月

  123. Numerical Investigation of Unsteady Shock/shock and Shock/vortex Interactions in Non-perfect Gas 査読有り

    Satoru Yamamoto

    Proc. of the 7th Int. Symp. on Computational Fluid Dynamics 1 640-645 1997年9月

  124. Parametric Study of Unsteady Hypersonic Shock/Shock Interference Flow using Shock-Vortex Capturing Method 査読有り

    Norinao Takasu, Satoru Yamamoto

    Proc. of Int. Conf. on Fluid Engineering, JSME Centennial Grand Congress 1 431-436 1997年7月

  125. Numerical Investigation of Condensation Effect to Unsteady Transonic Viscous Flows in Moist Air 査読有り

    Hideki Hagari, Satoru Yamamoto

    Proc. of Int. Conf. on Fluid Engineering, JSME Centennial Grand Congress III 1701-1706 1997年7月

  126. Navier-stokes analysis of unsteady transonic flows through gas turbine cascadeswith and without coolant ejection 査読有り

    T. Tanuma, N. Shibukawa, S. Yamamoto

    Proceedings of the ASME Turbo Expo 1 25-32 1997年

    出版者・発行元:American Society of Mechanical Engineers (ASME)

    DOI: 10.1115/97-GT-479  

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    An implicit time-marching higher-order accurate finitedifference method for solving the two-dimensional cornpressible Navier-Stokes equations was applied to the numerical analyses of steady and unsteady, subsonic and transonic viscous flows through gas turbine cascades with trailing edge coolant ejection. Annular cascade tests were carried out to verify the accuracy of the present analysis. The unsteady aerodynamic mechanisms associated with the interaction between the trailing edge vortices and shock waves and the effect of coolant ejection were evaluated with the present analysis.

  127. Stabilization of higher-order high resolution schemes for the compressible Navier-Stokes equations 査読有り

    H Daiguji, Yuan, X, S Yamamoto

    INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & FLUID FLOW 7 (2-3) 250-& 1997年

    出版者・発行元:MCB UNIV PRESS LTD

    DOI: 10.1108/09615539710163293  

    ISSN:0961-5539

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    Proposes a measure to stabilize the fourth(fifth)order high resolution schemes for the compressible Navier-Stokes equations. Solves the N-S equations of the volume fluxes and the low-Reynolds number k-epsilon turbulence model in general curvilinear co-ordinates by the delta-form implicit finite difference methods. Notes that, in order to simulate the flow containing weak discontinuities accurately, it is very effective to use some higher-order TVD upstream-difference schemes in the right-hand side of the equations of these methods; however, the higher-order correction terms of such schemes in general amplify the numerical disturbances. Therefore, restricts these terms here by operating the minmod functions to the curvatures so as to suppress the occurrence of new inflection points. Computes an unsteady transonic turbine cascade flow where vortex streets occur from the trailing edge of blades and interact with shock waves. Finds that the stabilization measure improves not only the computational results but also the convergency for such a complicated flow problem.

  128. Numerical Investigation of Shock/Vortex Interaction in Hypersonic Thermochemical Nonequilibrium Flow 査読有り

    S.Yamamoto, N.Takasu, H.Nagatomo

    Preprint of the AIAA 32nd Thermophysics Conference, AIAA Paper 97-2553 1-9 1997年

  129. An Application of q-w Turbulence Model to Numerical Simulation of Near Wake Flow 査読有り

    A. Lebedev, H. Daiguji, S. Yamamoto

    Computational Fluid Dynamics JOURNAL 5 (4) 509-526 1997年1月

  130. Navier-stokes analysis of unsteady transonic flows through gas turbine cascadeswith and without coolant ejection 査読有り

    T. Tanuma, N. Shibukawa, S. Yamamoto

    Proceedings of the ASME Turbo Expo 1 1-15 1997年

    出版者・発行元:American Society of Mechanical Engineers (ASME)

    DOI: 10.1115/97-GT-479  

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    An implicit time-marching higher-order accurate finitedifference method for solving the two-dimensional cornpressible Navier-Stokes equations was applied to the numerical analyses of steady and unsteady, subsonic and transonic viscous flows through gas turbine cascades with trailing edge coolant ejection. Annular cascade tests were carried out to verify the accuracy of the present analysis. The unsteady aerodynamic mechanisms associated with the interaction between the trailing edge vortices and shock waves and the effect of coolant ejection were evaluated with the present analysis.

  131. Shock-Vortex Capturing Method for Strongly Unsteady Flow Problems 査読有り

    S. Yamamoto

    Proc. of 15th Int. Conf. on Numerical Methods in Fluid Dynamics, Lecture Notes in Phys., Springer 490 590-595 1996年6月

  132. Structure of Bow Shock and Compression Wave Interaction in Unsteady Hypersonic Shock/Shock Interference Flow 査読有り

    S.Yamamoto, S.Kano

    AIAA Paper 96-2152 1-8 1996年

  133. 極超音速熱・化学非平衡を考慮した鈍頭物体後流の高解像度数値解析 査読有り

    長友 英夫, 山本 悟, 大宮司 久明

    日本機械学会論文集B編 62 (600) 3052-3057 1996年

    出版者・発行元:The Japan Society of Mechanical Engineers

    DOI: 10.1299/kikaib.62.3052  

    ISSN:0387-5016

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    An object which flies hypersonic speed, such as an aeroassisted orbital transfer vehicle, is affected greatly by not only the bow shock but also the expansion around the shoulder and the recompression of separated flow. Though the experiments to analyze this flow have been performed by some groups recently, there are some difficulties in measuring the ow because of limitations of instrumentation. Both experimental and numerical approaches are necessary to analyze the phenomena. The efficient numerical code which has been developed by the authors for hypersonic thermochemical non-equilibrium flow is applied to simulate the problem. The calculated results of different accuracy's in space, the perfect gas and the experimental data are compared.

  134. 湿度を考慮した遷音速粘性流れの数値解法 査読有り

    入屋 明広, 山本 悟, 大宮司 久明

    日本機械学会論文集B編 62 (603) 3854-3859 1996年

    DOI: 10.1299/kikaib.62.3854  

  135. Numerical investigation of shock interference in hypersonic thermochemical nonequilibrium flow 査読有り

    H Nagatomo, S Yamamoto, H Daiguji

    COMPUTATIONAL FLUID DYNAMICS '96 1 39-44 1996年

    出版者・発行元:JOHN WILEY & SONS LTD

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    Numerical investigations of hypersonic flow which causes shock-wake or shock-shock interference are performed considering thermochemical nonequilibrium. These interferences in the hypersonic flow must be solved by an accurate, robust and less dissipative numerical scheme. Two different methods, Implicit-Explicit Flux Vector Splitting(IEFVS) and AUSM-DV schemes are employed to satisfy these requirements. These schemes are coupled with the fourth-order MUSCL TVD scheme which enable us to capture shocks, vortices and shear layers clearly. As numerical examples, steady and unsteady hypersonic flows considering thermochemical nonequilibrium are calculated and the reliability of the present methods is discussed.

  136. Structure of Unsteady Shock/vortex Interaction behind the Object obtained by the Fourth-order Shock Capturing Method 査読有り

    S.Yamamoto, H.Daiguji

    Proc. of the Symp. on Mathematical Modeling of Turbulent Flows, The University of Tokyo I 369-374 1995年12月

  137. Numerical Investigation of Unsteady Shock/turbulent Boundary Layer Interactions in Turbomachinery 査読有り

    S.Yamamoto, H.Daiguji

    Proc. of the Symp. on Mathematical Modeling of Turbulent Flows, The University of Tokyo I 363-368 1995年12月

  138. Structure of Unsteady Hypersonic Shock/Shock Interference Flows obtained by the Higher-Resolution CFD Approach 査読有り

    S.Yamamoto, S.Kano, T.Okuyama, H.Daiguji

    Proc. of the Symp. on Mathematical Modeling of Turbulent Flows, The University of Tokyo I 375-380 1995年12月

  139. A Higher-Order CFD Approach to Shock/Vortex Interaction and its Application to Turbomachinery 招待有り 査読有り

    S.Yamamoto, X.Yuan, H.Daiguji

    Proc.of the 1995 Yokohama Int. Gas Turbine Congress I 27-34 1995年10月

  140. An implicit explicit flux vector splitting scheme for hypersonic thermochemical nonequilibrium flows 査読有り

    S Yamamoto, H Nagatomo, H Daiguji

    FOURTEENTH INTERNATIONAL CONFERENCE ON NUMERICAL METHODS IN FLUID DYNAMICS 453 314-319 1995年

    出版者・発行元:SPRINGER-VERLAG BERLIN

    ISSN:0075-8450

  141. An Efficient CFD Approach for Simulating Unsteady Hypersonic Shock-Shock Interference Flows 査読有り

    Shintaro Kano, Satoru Yamamoto, Hisaaki Daiguji

    Proc. of 6th Int. Symp. on Computational Fluid Dynamics 2 570-575 1995年

  142. Navier-Stokes Analysis of Unsteady Transonic Flows through Turbine Cascades 査読有り

    T.Tanuma, S.Yamamoto, X.Yuan, H.Daiguji

    Proc. of the Seventh Int. Symp. on Unsteady Aerodynamics and Aeroelasticity of Turbomachines, Elsevier Science I 691-707 1994年9月

    出版者・発行元:Elsevier Science.

  143. 非定常遷音速翼列流れの高解像差分スキ-ム 査読有り

    袁 新, 山本 悟, 大宮司 久明

    日本ガスタービン学会誌 22 (86) 29-35 1994年9月

    出版者・発行元:公益社団法人日本ガスタービン学会

    ISSN:0387-4168

  144. COMPUTATION OF UNSTEADY TRANSONIC CASCADE FLOW USING THE EULER AND NAVIER-STOKES EQUATIONS OF CONTRAVARIANT VELOCITIES 査読有り

    S YAMAMOTO, H DAIGUJI

    JSME INTERNATIONAL JOURNAL SERIES B-FLUIDS AND THERMAL ENGINEERING 37 (3) 522-530 1994年8月

    出版者・発行元:JAPAN SOC MECHANICAL ENGINEERS SANSHIN HOKUSEI BLDG

    DOI: 10.1299/jsmeb.37.522  

    ISSN:1340-8054

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    The purpose of the present paper is to investigate the steady and unsteady flows through subsonic and transonic turbine cascades using the Euler and Navier-Stokes (N-S) solvers developed by the authors. Use of the fundamental equations of contravariant velocity components also proposed by the authors is very convenient for treating several kinds of boundary conditions. Some efficient numerical schemes for the unsteady calculation, shock capturing and turbulent quantities are also developed. As numerical examples, we show the numerical results of some turbine cascade flows by assuming the flows to be inviscid or viscous (turbulent) and steady or unsteady. The results are compared with each other and with the experimental data. Finally, the reliability and the limitation of the present numerical solvers for the turbine cascade cases are discussed.

  145. Higher-Order Numerical Simulation of Unsteady Shock/Vortex Interactions 査読有り

    S.Yamamoto, A.Takahashi, H.Daiguji

    AIAA Paper 94-2305 1-8 1994年

  146. A Higher-Resolution Shock-Capturing Scheme for Simulating Unsteady Three-Dimensional Transonic Flows in Turbomachinery 査読有り

    X.Yuan, S.Yamamoto, H.Daiguji

    AIAA Paper 94-3199 1-8 1994年

  147. On the 4th-Order Compact MUSCL TVD Scheme Approached to Complex Flow Problems 査読有り

    Satoru Yamamoto, Hisaaki Daiguji

    Proc. of the 5th Int. Symposium on Computational Fluid Dynamics III 381-386 1993年9月

  148. Three-Dimensional Navier-Stokes Simulation of Transonic Cascade Flows Considering Unsteady Wakes 査読有り

    Xin Yuan, Satoru Yamamoto, Hisaaki Daiguji

    Proc. of the 5th Int. Symposium on Computational Fluid Dynamics III 421-426 1993年9月

  149. Unsteady Navier-Stokes Analysis of Transonic Cascade Flow in Turbomachinery 査読有り

    Tadashi Tanuma, Satoru Yamamoto, Xin Yuan, Hisaaki Daiguji

    Proc. of the 5th Int. Symposium on Computational Fluid Dynamics III 217-222 1993年9月

  150. A Higher-Order Accurate Navier-Stokes Solver for 3D Supersonic Mixing Layers with an Efficient Visualization Algorithm 査読有り

    Koichi Ishizaka, Yasushi Sugita, Satoru Yamamoto, Hisaaki Daiguji

    Proc. of the 5th Int. Symposium on Computational Fluid Dynamics I 358-362 1993年9月

  151. Application of Computational Fluid Dynamics to Large-Scale Turbine Blade Designs 査読有り

    Tadashi Tanuma, Xin Yuan, Satoru Yamamoto, Hisaaki Daiguji

    Proc. of JSME-ASME Int. Conf. on Power Engineering-93 2 (93) 361-366 1993年9月

  152. HIGHER-ORDER-ACCURATE UPWIND SCHEMES FOR SOLVING THE COMPRESSIBLE EULER AND NAVIER-STOKES EQUATIONS 査読有り

    S YAMAMOTO, H DAIGUJI

    COMPUTERS & FLUIDS 22 (2-3) 259-270 1993年3月

    出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD

    DOI: 10.1016/0045-7930(93)90058-H  

    ISSN:0045-7930

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    A fifth-order compact upwind TVD scheme and a fourth-order compact MUSCL TVD scheme are proposed for solving the compressible Euler and Navier Stokes equations. The fundamental form of the present schemes is based on the second(third)-order-accurate upwind scheme. One of the distinctive points using the present MUSCL TVD scheme is the ability to capture the discontinuities, such as slip lines or contact surfaces as well as shocks, more sharply th an the existing TVD scheme with a simpler algorithm than the so-called ENO scheme. The algorithms are relatively simple and the formulas are quite compact. They can be applied easily to the existing Euler and Navier Stokes solvers based on the second(third)-order upwind scheme. Finally, we show some numerical results of steady and unsteady flows, including shocks, weak discontinuities and vortices, and the superiority of the present scheme is confirmed by comparison with the results of the ordinary numerical scheme.

  153. 非定常圧縮性オイラ-方程式の四次精度 MUSCL差分スキ-ム 査読有り

    山本悟, 大宮司久明, 石坂浩一

    日本機械学会論文集B編 59 (557) 43-48 1993年1月

    出版者・発行元:一般社団法人日本機械学会

    DOI: 10.1299/kikaib.59.43  

    ISSN:0387-5016

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    A fourth-order compact MUSCL (Monotone Upstream-centered Scheme for Conservation Laws) TVD (Total Variation Diminishing) scheme is proposed for solving the unsteady compressible Euler Equations. The fundamental form of the present scheme is based on the second (third) -order accurate MUSCL finite-difference scheme. One of the distinctive features of this scheme is the ability to capture discontinuities such as slip lines or contact surfaces as well as shocks more sharply than the existing TVD schemes in spite of the use of a simpler algorithm than that of the so-called ENO scheme. Therefore, this scheme can be easily applied to any ordinary numerical solvers based on the second (third) -order MUSCL scheme. We also adopt this scheme into the existing Euler solver developed by the authors which can simulate unsteady inviscid flows accurately by means of the Newton iteration and the Crank-Nicholson method. In order to verify the reliability of the present scheme, an unsteady inviscid supersonic flow having oblique shocks and a slip line is computed. The results show that the slip line as well as oblique shocks can be captured completely.

  154. 蒸気タ-ビン翼列流れの遷音速流れの数値解析と風洞試験 査読有り

    田沼唯士, 山本悟, 池田隆, 大宮司久明

    日本機械学会論文集B編 58 (555) 3330-3336 1992年11月

    DOI: 10.1299/kikaib.58.3330  

  155. Numerical Analysis of Unsteady Turbulent Flows through Transonic Turbine and Compressor Cascades 査読有り

    S. Yamamoto, H. Daiguji

    Computational Fluid Dynamics JOURNAL 1 (1) 91-103 1992年4月

  156. Numerical Simulation of Supsersonic Mixing Layers using a Fouth-order Accurate Shock Capturing Scheme 査読有り

    Hisaaki Daiguji, Satoru Yamamoto, Koichi Ishizaka

    Proc. of 13th Int. Conf. on Numerical Methods in Fluid Dynamics, Lecture Notes in Phys., Springer-Verlag 414 315-319 1992年

  157. A Higher-Order Accurate Navier-Stokes Solver for Transonic and Supersonic Flows in Turbomachinery 査読有り

    S.Yamamoto, H.Daiguji

    AIAA Paper 92-3044 1-8 1992年

  158. Unsteady Navier-Stokes Simulation of Turbulent Flows through a Supersonic Compressor Cascade 査読有り

    S.Yamamoto, H. Daiguji

    Proc. of the First ASME/JSME Fluids Engineering Conference FED-120 73-79 1991年6月

  159. 非定常遷音速翼列流れ解析に適した数値シミュレ-タの開発 査読有り

    石坂浩一, 山本悟, 大宮司久明

    日本機械学会論文集B編 57 (544) 4130-4135 1991年

    出版者・発行元:一般社団法人日本機械学会

    DOI: 10.1299/kikaib.57.4130  

    ISSN:0387-5016

    詳細を見る 詳細を閉じる

    An efficient numerical simulator for calculating the unsteady transonic cascade flows and for visualizing these numerical data is developed. The authors have already developed a numerical method, in which an implicit time-marching finite-difference scheme for solving the unsteady Euler and Navier-Stokes equations in general curvilinear coordinates and several numerical techniques have been applied in order to simulate the unsteady flows having shocks and their induced boundary layer separations such as the flow through a transonic or supersonic compressor cascade. With regard to a system developed by us, a graphics work station having the power of the super-minicomputer was connected with an image recorder which can control a 16mm movie camara, and we have developed a computational code with the UNIX System which can calculate any flow and make the visualized film from the results at the same time. In particular, we can make an animation visualizing the unsteady transonic cascade flow within a half-day at most with no effort, Therefore, we should emphasize that the present system is one of the most effective tools for simulating unsteady flows.

  160. A NUMERICAL-METHOD FOR THE TRANSONIC CASCADE FLOW PROBLEM 査読有り

    S YAMAMOTO, H DAIGUJI

    COMPUTERS & FLUIDS 19 (3-4) 461-478 1991年

    出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD

    ISSN:0045-7930

    詳細を見る 詳細を閉じる

    An implicit time-marching finite-difference method for solving the three-dimensional compressible Navier-Stokes equations for the relative flow of a turbomachine impeller in general curvilinear coordinates is presented. The fundamental equations of the method have the distinctive feature that the momentums of the contravariant velocities are employed as the dependent variables. The use of the momentum equations of the contravariant velocities makes possible correct and simple treatments of some boundary conditions. In order to obtain the stable solution for high Reynolds number turbulent flow, the Navier-Stokes equations and the k-epsilon turbulence model equations are solved simultaneously, and a high-resolution TVD upwind scheme is introduced. The calculated results of some two-dimensional turbulent flows agreed well with the experimental data. The calculated results of an axial-flow transonic compressor rotor flow showed that the leakage vortex from the tip clearance as well as the shock waves can be captured vividly, in spite of the relatively coarse grid.

  161. Numerical Simulation of Unsteady Turbulent Flow through Transonic and Supersonic Cascades 査読有り

    Satoru Yamamoto, Hisaaki Daiguji

    Proc. of 12th Int. Conf. on Numerical Methods in Fluid Dynamics, Lecture Notes in Phys., Springer-Verlag 371 485-489 1990年7月

  162. A Streamwise TVD Scheme for Solving the Compressible Euler Equations 査読有り

    Satoru Yamamoto, Hisaaki Daiguji

    Proc. of Third Int. Conf. on Hyperbolic Problems, Uppsala II 980-991 1990年6月

  163. 三次元遷音速羽根車流れのナビエ・スト-クス解析と可視化 査読有り

    山本 悟, 大宮司 久明, 池田 修司

    日本機械学会論文集B編 56 (523) 765-772 1990年3月

    出版者・発行元:The Japan Society of Mechanical Engineers

    DOI: 10.1299/kikaib.56.765  

    ISSN:0387-5016

    詳細を見る 詳細を閉じる

    The purpose of this paper is, first, to analyze 3-D transonic cascade flow by using the TVD Navier-Stokes code developed by the authors. Since the momentum equations of contravariant velocities are used in the code, the treatments of boundary conditions, especially the solid wall and the periodic boundaries for the 3-D cascade flow, become very easy. A Chakravarthy-Osher type TVD scheme modified by the authors is adopted in order to clearly simulate 3-D complex flow having shock waves and separation bubbles. The second purpose is to visualize the computed results by using the 3-D color graphic display. As numerical examples, the 3-D viscous flows thorough a transonic axial-flow compressor rotor with or without a tip clearance are computed, and the colored oli-flow patterns, 3-D particle paths, 3-D time lines which show the shock/boundary layer interactions and a leakage vortex near the casing wall are obtained. In particular, the mechanism of occurrence of the leakage vortex is investigated in detail.

  164. A Numerical Method for Solving the Unsteady Compressible Navier-Stokes Equations 査読有り

    Satoru Yamamoto, Hisaaki Daiguji

    Proc. of Int. Symp. on Computational Fluid Dynamics-Nagoya II 710-715 1989年8月

  165. タ-ボ機械の三次元圧縮性翼列流れのコンピュ-タシミュレ-ション 査読有り

    山本 悟, 大宮司久明, 大槻康彦

    流れの可視化写真集 6 42-47 1989年7月

  166. 反変速度成分のオイラ-またはナビエ・スト-クス方程式を用いた遷音速翼列流れの計算 査読有り

    山本 悟, 大宮司久明, 伊藤一道

    日本機械学会論文集B編 55 (515) 1943-1951 1989年7月

    出版者・発行元:The Japan Society of Mechanical Engineers

    DOI: 10.1299/kikaib.55.1943  

    ISSN:0387-5016

    詳細を見る 詳細を閉じる

    Implicit time-marching finite-difference methods for solving the two- and three-dimensional compressible Euler and Navier-Stokes equations are presented. The distinctive feature of these methods is to use the momentum equations of contravariant velocity components. By using such equations, accurate and easy treatments of the solid wall boundary condition are realized for the Euler equations, and simple treatments of he periodic boundary condition become possible for the impeller flows. The numerical method are based on the Beam-Warming delta-form approximate-factorization scheme, and take into consideration the diagonalization and upstreaming by the theory of characteristics. The computations of turbulent flows are implemented using the two-equation k-ε turbulence model with the law of the wall. Finally, some numerical results of transonic cascade flow are shown.

  167. An Implicit Time-Marching Method for Solving the 3-D Compressible Navier-Stokes Equations 査読有り

    Hisaaki Daiguji, Satoru Yamamoto

    Proc. of 11th Int. Conf. on Numerical Methods in Fluid Dynamics, Lecture Notes in Phys., Springer-Verlag 323 210-214 1989年

  168. 反変速度成分の三次元オイラ-方程式の各種差分スキ-ムとタ-ボ機械の流れへの応用 査読有り

    権 正吾, 山本 悟, 伊藤 一道, 大宮司 久明

    ターボ機械 16 (2) 74-80 1988年2月

    出版者・発行元:Turbomachinery Society of Japan

    DOI: 10.11458/tsj1973.16.74  

    ISSN:0385-8839

  169. An Implicit Time-Marching Scheme for Solving the Compressible Navier-Stokes Equations 査読有り

    S. Yamamoto, H. Daiguji

    Proc. of the Int. Symp. on Computational Fluid Dynamics, Sydney, published by North-Holland 1 773-784 1988年

    出版者・発行元:Elsevier Science Publishers B. V.

  170. 三次元圧縮性オイラ-方程式の時間進行差分法 査読有り

    大宮司 久明, 山本 悟, 本橋 康夫

    日本機械学会論文集B編 53 (486) 393-399 1987年

    出版者・発行元:The Japan Society of Mechanical Engineers

    DOI: 10.1299/kikaib.53.393  

    ISSN:0387-5016

    詳細を見る 詳細を閉じる

    Explicit and implicit time-marching finite-difference schemes are proposed for analysing three -dimensional steady and unsteady inviscid transonic flows. These schemes are different from the existing methods since the Euler equations of contravariant velocities in general curvilinear coordinates are used. However, some computational techniques used in the existing methods, such as linearization, diagonalization and upstreaming are also applied to these schemes. The finally obtained equations for the numerical computation have almost the same complexity as the corresponding existing methods. The remarkable feature of these methods is the ability to treat solid wall boundary conditions easily and exactly including, implicit schemes. A calculated result of shocked transonic flow through a converging-diverging square nozzle is shown.

  171. Computation of Transonic Cascade Flow Using the Euler and Navier-Strokes Equations of Contravariant Velocities 査読有り

    S. Yamamoto, H. Daiguji, K. Ito

    Proc. of the 1987 Tokyo Int. Gas Turbine Congress II 295-302 1987年

  172. AN EFFICIENT TIME-MARCHING SCHEME FOR SOLVING COMPRESSIBLE EULER EQUATIONS 査読有り

    H DAIGUJI, S YAMAMOTO

    BULLETIN OF THE JSME-JAPAN SOCIETY OF MECHANICAL ENGINEERS 29 (255) 2845-2850 1986年9月

    出版者・発行元:JAPAN SOC MECHANICAL ENGINEERS SANSHIN HOKUSEI BLDG

    ISSN:0021-3764

  173. An Implicit Time-marching Method for Solving the 3-D Compressible Euler Equations 査読有り

    H. Daiguji, Y. Motohashi, S. Yamamoto

    Proc. of 10th Int. Conf. on Numerical Methods in Fluid Dynamics, Lecture Notes in Phys., Springer-Verlag 264 205-210 1986年

  174. An Efficient Time-Marching Method for Solving the Compressible Euler Equations 査読有り

    H. Daiguji, S. Yamamoto

    Proc. of Int. Symp. on Computational Fluid Dynamics-Tokyo 1 217-228 1985年

︎全件表示 ︎最初の5件までを表示

MISC 107

  1. 巻頭言、スーパーコンピュータ SX と歩んだ研究者人生 招待有り

    山本悟

    東北大学サイバーサイエンスセンター大規模科学計算システム広報SENAC 57 (1) 1-2 2024年1月

    出版者・発行元:東北大学サイバーサイエンスセンター

  2. デジタルツイン数値タービンへの道 招待有り

    山本悟

    日本機械学会流体工学部門ニュースレター 11月号 2023年11月

  3. 機械工学年鑑2023「流体工学」章代表者 招待有り 査読有り

    山本悟

    日本機械学会ホームページ https://www.jsme.or.jp/kikainenkan2023/ 2023年7月

  4. 東北大学山本(悟)・古澤研究室の紹介 招待有り 査読有り

    山本悟, 古澤卓

    日本ガスタービン学会誌 51 (4) 7-9 2023年7月

  5. デジタルツイン数値タービンの研究開発 招待有り 査読有り

    山本悟, 宮澤弘法, 古澤卓

    ターボ機械5月号(日本工業出版) 2023年5月

  6. 持続可能社会に向けたデジタルツインガスタービンの研究開発,マルチフィジックスCFDアプリ:数値タービン 招待有り

    山本悟, 古澤卓, 宮澤弘法

    クリーンエネルギー(日本工業出版) 31 (3) 32-36 2022年3月

    ISSN:0918-7510

  7. 連続水熱合成反応器内の超臨界水混合流動LES

    古澤卓, 名古屋雄大, 山本悟, 横哲, 阿尻雅文

    数値流体力学シンポジウム講演論文集(CD-ROM) 36th 2022年

    ISSN:2433-2674

  8. 全周流動計算に基づく発電用ガスタービン圧縮機部分負荷運転時の安定性向上の検討

    萩田泰晴, 宮澤弘法, 古澤卓, 山本悟

    日本ガスタービン学会定期講演会講演論文集(CD-ROM) 50th 2022年

    ISSN:2432-6739

  9. 部分負荷運転時の発電用ガスタービン圧縮機を通る湿り空気流れの全周解析

    徳山好紀, 萩田泰晴, 宮澤弘法, 古澤卓, 山本悟

    日本ガスタービン学会定期講演会講演論文集(CD-ROM) 50th 2022年

    ISSN:2432-6739

  10. 連続水熱合成反応器における超臨界水の乱流混合流動シミュレーション

    松井建太, 古澤卓, 山本悟, 横哲, 阿尻雅文

    数値流体力学シンポジウム講演論文集(CD-ROM) 35th 2021年

    ISSN:2433-2674

  11. 電力負荷変動対応時の実機ガスタービンコンプレッサー内部非定常流動解析

    萩田泰晴, 徳山好紀, 宮澤弘法, 古澤卓, 山本悟, 梅沢修一, 米澤宏一, 鈴木武志, 大森修一

    日本ガスタービン学会定期講演会講演論文集(CD-ROM) 49th 2021年

    ISSN:2432-6739

  12. 実在気体効果を考慮した高圧二酸化炭素の非平衡凝縮流れの数値解析

    古澤卓, 小島匠, 宮澤弘法, 山本悟

    数値流体力学シンポジウム講演論文集(CD-ROM) 34th 2020年

    ISSN:2433-2674

  13. エロージョンにより変形した静翼列を伴う蒸気タービン中圧段の非定常流動シミュレーション

    船迫昌平, 宮澤弘法, 古澤卓, 山本悟, 米澤宏一, 梅沢修一, 大森修一, 鈴木武志

    数値流体力学シンポジウム講演論文集(CD-ROM) 34th 2020年

    ISSN:2433-2674

  14. 蒸気タービン中圧段静翼カットバックに関する非定常流動シミュレーション

    宮澤弘法, 上村晃弘, 古澤卓, 山本悟, 梅沢修一, 米澤宏一, 大森修一, 鈴木武志

    日本機械学会年次大会講演論文集(CD-ROM) 2020 2020年

    ISSN:2424-2667

  15. 非平衡凝縮を伴うマルチフィジックス熱流動のシミュレーション技術,特集「マルチフィジックスシミュレーションの進展」 招待有り 査読有り

    山本悟, 古澤卓

    日本ガスタービン学会誌 47 (6) 389-395 2019年11月

  16. 数値タービンのスーパーコンピューティング 招待有り 査読有り

    山本 悟

    化学工学会誌 88 (6) 337-339 2019年6月

  17. ガスタービン用圧縮機翼列流れへの湿りの影響に関する数値的研究-第3報:Rotor37における湿り空気の凝縮-

    森口昇太, 宮澤弘法, 古澤卓, 山本悟

    日本ガスタービン学会定期講演会講演論文集(CD-ROM) 47th 2019年

    ISSN:2432-6739

  18. 蒸気タービン中圧三段の非定常流動シミュレーション

    宮澤弘法, 上村晃弘, 古澤卓, 山本悟, 米澤宏一, 梅沢修一, 大森修一

    数値流体力学シンポジウム講演論文集(CD-ROM) 33rd 2019年

    ISSN:2433-2674

  19. 低圧タービン翼のカットバックに関するLES

    森口昇太, 宮澤弘法, 古澤卓, 山本悟

    数値流体力学シンポジウム講演論文集(CD-ROM) 33rd 2019年

    ISSN:2433-2674

  20. 超臨界CO2流れのシミュレーション技術 招待有り 査読有り

    山本 悟

    日本ガスタービン学会ガスタービンセミナー 2019年1月

  21. Steam Turbine Tutrial: A Free Energy Perspective on Homogneous Nucleation Model 招待有り

    ASME 2018 Turbo Expo (GT2018-77505) 2018年5月

  22. ガスタービン用圧縮機翼列流れへの湿りの影響に関する数値的研究-第2報:Rotor37の湿り空気流動解析-

    森口昇太, 宮澤弘法, 古澤卓, 山本悟

    日本ガスタービン学会定期講演会講演論文集(CD-ROM) 46th 2018年

    ISSN:2432-6739

  23. 遷臨界条件下における三次元ラバルノズル内の非平衡凝縮シミュレーション

    古澤卓, 宮澤弘法, 森口昇太, 山本悟

    数値流体力学シンポジウム講演論文集(CD-ROM) 32nd 2018年

    ISSN:2433-2674

  24. 高解像度差分スキームを用いた湿り空気流動の数値解析

    森口昇太, 宮澤弘法, 古澤卓, 山本悟

    数値流体力学シンポジウム講演論文集(CD-ROM) 32nd 2018年

    ISSN:2433-2674

  25. ガスタービン用圧縮機翼列流れへの湿りの影響に関する数値的研究(第1報)Rotor37による数値タービンの検証—A numerical study of wetness effects on gas turbine compressor flow field : The verification of Numerical Turbine on NASA rotor 37

    森口 昇太, 宮澤 弘法, 古澤 卓, 山本 悟, 田中 隆太, 青塚 瑞穂

    日本ガスタービン学会定期講演会講演論文集 / 日本ガスタービン学会 編 45 47-52 2017年10月

    出版者・発行元:日本ガスタービン学会

    ISSN:2432-6593

  26. ガスタービン用圧縮機翼列流れへの湿りの影響に関する数値的研究-第1報:Rotor37による数値タービンの検証-

    森口昇太, 宮澤弘法, 古澤卓, 山本悟, 田中隆太, 青塚瑞穂

    日本ガスタービン学会定期講演会講演論文集 45th 2017年

    ISSN:2432-6593

  27. 軸流圧縮機遷音速湿り空気流れの数値シミュレーション

    森口昇太, 宮澤弘法, 古澤卓, 山本悟

    数値流体力学シンポジウム講演論文集(CD-ROM) 31st 2017年

    ISSN:2433-2674

  28. 高圧条件における二酸化炭素のラバルノズル内部非平衡凝縮シミュレーション

    古澤卓, 宮澤弘法, 森口昇太, 山本悟

    数値流体力学シンポジウム講演論文集(CD-ROM) 31st 2017年

    ISSN:2433-2674

  29. 蒸気タービン低圧段における非定常衝撃波干渉の数値解析

    宮澤弘法, 古澤卓, 山本悟

    数値流体力学シンポジウム講演論文集(CD-ROM) 31st 2017年

    ISSN:2433-2674

  30. 非平衡凝縮流れ解析に関する最近の研究動向

    山本悟, 古澤卓, 宮澤弘法

    日本ガスタービン学会定期講演会講演論文集 44th 2016年

    ISSN:2432-6593

  31. 非平衡凝縮および平衡凝縮が蒸気タービン多段長翼列に与える影響に関する数値的評価

    宮澤弘法, 服部雄真, 古澤卓, 山本悟

    数値流体力学シンポジウム講演論文集(CD-ROM) 30th 2016年

    ISSN:2433-2674

  32. 高圧条件における水蒸気のノズル内部の非平衡凝縮シミュレーション

    古澤卓, 宮澤弘法, 山本悟

    数値流体力学シンポジウム講演論文集(CD-ROM) 30th 2016年

    ISSN:2433-2674

  33. 凝縮を伴う超臨界二酸化炭素の遷音速流動シミュレーション

    古澤卓, 宮澤弘法, 山本悟

    日本機械学会年次大会講演論文集(CD-ROM) 2016 2016年

    ISSN:2424-2667

  34. 実機翼枚数を考慮した蒸気タービン低圧段長翼列に作用する非定常空力解析

    宮澤弘法, 古澤卓, 山本悟

    日本機械学会年次大会講演論文集(CD-ROM) 2016 2016年

    ISSN:2424-2667

  35. 複数FPGAによる並列流体計算と帯域圧縮通信による性能向上

    上野知洋, 佐野健太郎, 山本悟

    数値流体力学シンポジウム講演論文集(CD-ROM) 30th 2016年

    ISSN:2433-2674

  36. 1610 実機低圧タービンを通る非定常湿り蒸気流れの複数流路解析

    宮澤 弘法, 山本 悟

    流体工学部門講演会講演論文集 2015 "1610-1"-"1610-2" 2015年11月7日

    出版者・発行元:一般社団法人日本機械学会

    ISSN:1348-0251

    詳細を見る 詳細を閉じる

    Unsteady wet-steam flows through a three-stage low-pressure steam-turbine model developed by Mitsubishi Heavy Industry are numerically investigated. We solved compressible Nervier-Stokes equations coupled with nonequilibrium condensation models and SST turbulence model. Numerical results obtained by assuming single passage and multi passage are compared with each other and the effect of the blade number on unsteady wet-steam flows in the real low-pressure steam turbine is discussed. Numerical results are also compared with the experimental data.

  37. 1608 超臨界二酸化炭素の二次元翼列遷音速流動シミュレーション

    古澤 卓, 宮澤 弘法, 山本 悟

    流体工学部門講演会講演論文集 2015 "1608-1"-"1608-2" 2015年11月7日

    出版者・発行元:一般社団法人日本機械学会

    ISSN:1348-0251

    詳細を見る 詳細を閉じる

    Brayton Cycle of CO_2 has been recognized as an attractive new method for power generation. In this cycle, Supercritical CO_2 is compressed and heated beyond the critical pressure and temperature. Transonic flows through a compressor cascade are investigated under the supercritical condition by our numerical method coupled with the condensation model. The condensation by the temperature decreasing is found near the leading edge.

  38. J0520101 蒸気タービン低圧最終段を通る三次元非定常熱流動空力解析

    宮澤 弘法, 三宅 哲, 山本 悟

    年次大会 : Mechanical Engineering Congress, Japan 2015 "J0520101-1"-"J0520101-3" 2015年9月13日

    出版者・発行元:一般社団法人日本機械学会

    詳細を見る 詳細を閉じる

    In this paper, unsteady forces of wet-steam flows through real steam turbine low pressure final three stages developed by Mitsubishi Heavy Industry are numerically investigated. Compressible Nervier-Stokes equations coupled with nonequilibrium condensation models are simultaneously solved. The SST-model is also employed for evaluating the eddy-viscosity. Time-dependent pressure distributions on three-stage stator-rotor blade surfaces at constant spans are plotted to show the magnitude and the variation of unsteady forces locally. And then, the flow mechanism, how such unsteady forces are generated from the wet-steam flow through the multi-stage blade rows, is predicted.

  39. J0520302 圧縮機翼列を通る超臨界二酸化炭素の遷音速流動解析

    古澤 卓, 山本 悟

    年次大会 : Mechanical Engineering Congress, Japan 2015 "J0520302-1"-"J0520302-4" 2015年9月13日

    出版者・発行元:一般社団法人日本機械学会

    詳細を見る 詳細を閉じる

    Supercritical CO_2 has been recognized as an attractive new method for power generation. In this system, Supercritical CO_2 is compressed and heated beyond the critical pressure and temperature. In this study, transonic flows through a compressor cascade are investigated under the supercritical pressure condition by our numerical method. A detached bow shock is found near the leading edge and a normal shock is captured between the blades. The results are compared with those of the atmospheric condition.

  40. J0520201 超臨界流体乱流シミュレーションの数値解法

    斉 士博, 古澤 卓, 山本 悟

    年次大会 : Mechanical Engineering Congress, Japan 2015 "J0520201-1"-"J0520201-4" 2015年9月13日

    出版者・発行元:一般社団法人日本機械学会

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    The numerical simulation of turbulent supercritical water flows is presented. In the present method, the supercritical-fluids simulator is coupled with the building-cube method because of its simplicity and efficiency, and a meshless method is implemented as a wall boundary treatment because of its flexibility and adaptability. The implementation of the SST turbulence model has been accomplished to deal with the turbulent supercritical-fluid flows. The supercritical water jet submerged in a subcritical water environment is simulated, which is a typical process of supercritical-fluid flows in the hydrothermal spallation drilling application. First, turbulence model implementation verification is proposed with the classical case of zero pressure gradient flat plate. Then, the effects of temperature and pressure on the behavior of the supercritical water jets are investigated.

  41. ビルディングキューブ法に基づく流体専用計算機のキューブ間データ交換に関する一考察 (VLSI設計技術)

    上野 友也, 上野 知洋, 佐野 健太郎, 山本 悟

    電子情報通信学会技術研究報告 = IEICE technical report : 信学技報 114 (426) 79-84 2015年1月29日

    出版者・発行元:一般社団法人電子情報通信学会

    ISSN:0913-5685

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    本研究ではビルディングキューブ法(BCM)に基づく並列流体計算を高速化するために、FPGAによる専用計算機の開発を行っている。BCMでは、キューブと呼ぶ大小様々な立方体領域を単位としてデータ並列計算を行う。全てのキューブは同解像度の直交格子である。BCMは負荷分散に優れた並列計算方式であるものの、非圧縮性流体計算を行う場合にはその低い演算密度により計算性能がメモリ帯域に制約されるという問題がある。また、BCMでは隣接キューブの袖領域データを交換する必要があり、そのデータ転送や補間計算のオーバーヘッドにより並列処理効率が低下する問題が指摘されている。本稿では、メモリ帯域あたりの計算性能を向上させるためのストリームによるキューブ計算に加え、BCM専用計算機において高効率のキューブ間データ交換を実現するためのデータ転送・補間方式、およびそのハードウェア機構について考察する。

  42. 予測残差長の偏りを利用した小面積帯域圧縮ハードウェアの提案 (VLSI設計技術)

    上野 知洋, 伊藤 涼, 佐野 健太郎, 山本 悟

    電子情報通信学会技術研究報告 = IEICE technical report : 信学技報 114 (426) 73-78 2015年1月29日

    出版者・発行元:一般社団法人電子情報通信学会

    ISSN:0913-5685

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    本稿では,ハードウェアによる数値計算を高性能化する,帯域圧縮のための小面積データ圧縮ハードウェアの実現手法について述べる.FPGAを用いた数値計算への帯域圧縮適用には,複数チャネル化への対応のため圧縮ハードウェアの大幅な小面積化が不可欠である.面積増大の原因となるバレルシフタのリソース使用を削減するために,予測残差長の偏りを利用した手法を提案する.この提案手法に対して,モデル化した残差長分布による圧縮性能評価を行い,圧縮率の傾向と適用するデータについての考察を行う.また,ハードウェア実装による回路面積の評価から,帯域圧縮ハードウェアの小面積化を実現できたことを示す.これらの評価から得られた圧縮性能と回路面積の両方において,提案手法が小面積帯域圧縮ハードウェア実現に有効であることを示す.

  43. 実機低圧タービンを通る非定常湿り蒸気流れの複数流路解析

    宮澤弘法, 山本悟

    日本機械学会流体工学部門講演会講演論文集(CD-ROM) 93rd 2015年

    ISSN:1348-2882

  44. 超臨界二酸化炭素の二次元翼列遷音速流動シミュレーション

    古澤卓, 宮澤弘法, 山本悟

    日本機械学会流体工学部門講演会講演論文集(CD-ROM) 93rd 2015年

    ISSN:1348-2882

  45. 湿りを伴う実機タービンの低圧段長翼列に作用する非定常空力解析

    宮澤弘法, 三宅哲, 山本悟

    数値流体力学シンポジウム講演論文集(CD-ROM) 29th 2015年

    ISSN:2433-2674

  46. メモリ帯域圧縮ハードウェアを用いた数値計算の高性能化

    上野知洋, 佐野健太郎, 山本悟

    情報処理学会研究報告(Web) 2015 (HPC-151) 2015年

  47. 帯域圧縮による数値計算ハードウェアの高性能化

    上野知洋, 佐野健太郎, 山本悟

    数値流体力学シンポジウム講演論文集(CD-ROM) 29th 2015年

    ISSN:2433-2674

  48. 複数ストリームのための帯域圧縮ハードウェアの実装と評価

    上野 知洋, 伊藤 涼, 佐野 健太郎, 山本 悟

    研究報告システムLSI設計技術(SLDM) 2014 (24) 1-6 2014年1月21日

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    本稿では,FPGA 上に実装した数値シミュレーション専用カスタム計算機の入出力帯域を向上させるための,複数のデータストリームに対する圧縮・展開手法について述べる.計算回路へは,複数ストリーム間においてデータを同期して入力する必要がある.圧縮率の差異により,元データが異なる位置に符号化されてしまうため,複数の圧縮ストリームの同期が必要となる.本研究では複数圧縮ストリーム間の同期方式と,そのためのハードウェア設計を提案する.また,設計した複数ストリーム圧縮・展開ハードウェアの回路面積と最大動作周波数を測定し,ハードウェアとしての性能を評価する.Bandwidth enhancement with lossless data compression is one of the key solutions to improve performance of custom stream computing with FPGAs. Actual computing kernels require multiple streams, which should be compressed and encoded into a single channel to be written to external memories. Although the computing kernel requires synchronized data elements from multiple streams, difference in compression ratio makes streams have various speeds to feed their original data. Therefore we need a mechanism to synchronize multiple compressed streams. This paper presents a synchronized encoding method for compressed streams, and its hardware design. We also evaluate the hardware with the area and the maximum frequency in preparation for practical usage.

  49. ストリームプロセッサ自動生成コンパイラの開発と格子ボルツマン法専用計算コアへの適用

    伊藤涼, 鈴木隼人, 上野知洋, 佐野健太郎, 山本悟

    数値流体力学シンポジウム講演論文集(CD-ROM) 28th 2014年

    ISSN:2433-2674

  50. ワークショップ「CFDの産業活用における方向性」,マルチフィジックスCFDの産業応用 招待有り 査読有り

    山本悟

    日本機械学会2013年度年次大会DVD論文集 2013年9月

    出版者・発行元:日本機械学会

  51. 密結合FPGAクラスタによる格子ボルツマン法専用計算機の設計と実装

    鈴木隼人, 高野芳彰, 千葉諒太郎, 佐野健太郎, 山本悟

    第75回全国大会講演論文集 2013 (1) 127-128 2013年3月6日

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    本研究では、高効率なカスタムコンピューティングを目的として、FPGAを用いた格子ボルツマン法専用計算機の開発を行っている。この専用計算機の計算要素は、計算格子を走査して得られるデータストリームに対し、ストリーミング計算を行う。また、計算要素を2次元アレイ構造に配置することにより、時間的及び空間的に並列に計算を行うことが可能となる。本稿では、計算要素の設計の詳細、および密結合FPGAクラスタによる試作実装について述べる。

  52. ビルディングキューブ法に基づく非圧縮性流体計算の専用計算機アーキテクチャに関する一考察

    千葉諒太郎, 高野芳彰, 佐野健太郎, 山本悟, 佐々木大輔, 中橋和博

    第75回全国大会講演論文集 2013 (1) 129-130 2013年3月6日

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    本研究ではビルディングキューブ法による流体計算を高速に行うカスタムアクセラレータの実現を目的とし、FPGAによる試作実装を行っている。本稿ではその仮アーキテクチャを提案し、性能評価を行う。計算機の性能を制限する主な要因は、バンド幅不足による演算器稼働率の低下である。このことから、仮アーキテクチャの設計要件を任意に増加可能な計算要素及び必要最小限のデータ移動による計算とし、設計を行う。性能評価においては、仮アーキテクチャのパラメータが性能に与える影響と最も大きなバンド幅を要求する接続を明らかにする。さらに、計算ステージ毎の実効バンド幅及び計算時間から、もっとも効果的に性能を上昇させるステージを特定する。

  53. 異なるビット幅を扱う浮動小数点データストリーム圧縮ハードウェアの性能評価

    上野 知洋, 高野 芳彰, 佐野 健太郎, 山本 悟

    研究報告システムLSI設計技術(SLDM) 2013 (4) 1-6 2013年1月9日

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    本稿では,浮動小数点データストリームを対象とした圧縮・展開ハードウェアのパラメータ化と,実装した異なるピット幅のデータを扱うハードウェアに関する性能評価について述べる.入力ピット幅が 32,64,128,256bit の圧縮・展開ハードウェアを ALTERA Stratix lV FPGA 上に実装し,その回路面積と動作周波数を評価した.回路面積はピット幅が大きくなるにつれ増大するが, 32,64bit の場合には,圧縮・展開ハードウエアを 4 セット実装しても評価に使用した FPGA 全体の 10% 以下の回路面積で実装可能であった.また,動作周波数の評価では入力ピット幅が 64bit 以下であれば 200MHz 以上での動作が可能という結果が得られた.同時に行った圧縮率の評価において, 32bit の浮動小数点データに対して 3.5,64bit のデータに対して 4.5 程度の圧縮率が得られた.これは評価したデータがストリーム計算時に使用する帯域を 1/3.5 もしくは 1/4.5 に削減することを意味する.This paper shows the parametalized design and the performance evaluation of data compressors and decompressors for floating-point data stream. We implement the hardware whose input bit widths are 32, 64, 128 and 256 on ALTERA Stratix IV FPGA. The evaluation result shows the area becomes larger when input bit width increase. But when the input bit widths are 32 and 64, the area are less than 10 % of the total resource on the FPGA if 4 sets of the compressor and the decompressor are implemented. The hardware can operate at more than 200MHz when bit widths are 32 and 64. Average compression ratios are 3.5 for 32 bit and 4.5 for 64 bit on test data compression.

  54. FPGAクラスタによる格子ボルツマン法専用計算機の実装と性能評価

    高野 芳彰, 鈴木 隼人, 千葉 諒太郎, 佐野 健太郎, 山本 悟

    研究報告システムLSI設計技術(SLDM) 2013 (29) 1-6 2013年1月9日

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    本論文では、密結合 FPGA クラスタ上に構築される LBM 専用計算機の試作実装及び性能評価について述べる。一般に、強スケーリングによる並列計算では、ノード数が増えるにつれて各ノードが担当する計算サイズが減少するため通信時間を隠蔽できなくなり、速度向上が得られなくなる。本研究では、これまで、強スケーリングにおいても高い性能スケーラビリティを達成可能なシステムを実現するため、低遅延且つ広帯域な専用ネットワークを有する密結合 FPGA クラスタを提案してきた。本専用ネットワークをアクセラレータドメインネットワーク (ADN) と呼ぶ。本稿では、まず LBM 専用計算機のアーキテクチャおよびストリーム計算手法について述べる。その後、 FPGA クラスタ中の単一 FPGA を用いた試作実装による性能評価を行う。This paper reports prototype implementation and performance evaluation of a custom computing machine for the Lattice Boltzmann method (LBM) to be implemented on our tightly-coupled FPGA cluster. In general, strong scaling prevents performance from scaling with the number of computing nodes because it gets difficult to hide communication time with computing time. In our research, to solve this problem, we have proposed and developed the tightl-coupled FPGA cluster with an accelerator-domain network (ADN) to provide low-latency and high-bandwidth direct connection for FPGAs. In this paper, we describe the architecute and stream computation of the LBM custom computing machine. We evaluate its performance based on prototype implementation with a single FPGA of the FPGA cluster.

  55. 複数データストリームの帯域向上のための圧縮ハードウェアの実装と評価

    上野知洋, 高野芳彰, 佐野健太郎, 山本悟

    電子情報通信学会技術研究報告 113 (52(RECONF2013 1-19)) 2013年

    ISSN:0913-5685

  56. 密結合FPGAクラスタを用いた高効率LBM専用計算機の性能評価

    伊藤涼, 千葉諒太郎, 鈴木隼人, 上野知洋, 佐野健太郎, 山本悟

    電気関係学会東北支部連合大会講演論文集(CD-ROM) 2013 2013年

  57. 浮動小数点データストリーム圧縮ハードウェアの試作実装と評価

    上野知洋, 高野芳彰, 佐野健太郎, 山本悟

    電子情報通信学会技術研究報告 112 (70(RECONF2012 1-23)) 2012年

    ISSN:0913-5685

  58. 数値データストリーム圧縮ハードウェアの性能評価

    上野知洋, 高野芳彰, 佐野健太郎, 山本悟

    数値流体力学シンポジウム講演論文集(CD-ROM) 26th 2012年

    ISSN:2433-2674

  59. B-14 部分流入段の三次元非定常流動解析に基づく性能予測(空力・CFD,一般講演)

    笹尾 泰洋, 高田 真司, 田沼 唯士, 山本 悟

    ガスタービン定期講演会講演論文集 (39) 159-162 2011年7月6日

    出版者・発行元:公益社団法人日本ガスタービン学会

    ISSN:0919-1941

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    In this paper, the performance of a partial admission stage is parametrically predicted using the high-order high-resolution numerical method developed by our group. Compressible Navier-Stokes equations are solved by the high-order high-resolution finite-difference method based on the fourth-order compact MUSCL TVD scheme, Roe's approximate Riemann solver, and the LU-SGS scheme. The SST-model is also solved for evaluating the eddy-viscosity. Unsteady three-dimensional flows through half-arc nozzle-rotor cascade channels considering a partial admission are numerically investigated. 54 nozzle passages with two blockages and 30 rotor passages are simultaneously calculated. The influence of the flange in the nozzle box to the lift of rotors is predicted.

  60. 高性能格子ボルツマン計算のためのマルチFPGAアクセラレータの性能見積り

    高野芳彰, 佐野健太郎, 山本悟

    先進的計算基盤システムシンポジウム論文集 2011 268-268 2011年5月18日

  61. 低メモリ帯域で高性能ステンシル計算を実現するスケーラブルストリーミングアレイの試作と評価

    佐野 健太郎, 初田 義明, 高野 芳彰, 山本 悟

    電子情報通信学会技術研究報告. RECONF, リコンフィギャラブルシステム : IEICE technical report 111 (31) 79-84 2011年5月5日

    出版者・発行元:一般社団法人電子情報通信学会

    ISSN:0913-5685

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    ステンシル計算は科学技術計算において重要な計算カーネルの一つであるものの、その小さな演算密度のために、マルチコアプロセッサやGPGPUでは限られたメモリ帯域により実効性能が制約されてしまう。本研究では、複数のFPGAから成るシステムにおいて高性能ステンシル計算を実現するスケーラブルストリーミングアレイ(SSA)を提案する。SSAは、多段のパイプライン処理により、一定の外部メモリ帯域に対して線形の速度向上を実現する。本稿では、SSAの設計を示すと共に、複数のFPGAに対する性能モデルを導出する。9つのStratix III FPGAを用いて実装されたSSAは、僅か2GB/sの外部メモリ帯域に対してピーク性能の87.4%にあたる260GFlop/sの2次元ヤコビ計算を実現した。これは、中規模以上の計算サイズ対して得られる線形の速度向上によるものである。

  62. 浮動小数点データ圧縮ハードウェアのための複数ストリーム符号化方式 (システムLSI設計技術(SLDM) Vol.2011-SLDM-148)

    佐野 健太郎, 片平 和也, 山本 悟

    情報処理学会研究報告 2010 (5) 6p 2011年2月

    出版者・発行元:情報処理学会

    ISSN:1884-0930

  63. 浮動小数点データ圧縮ハードウェアのための複数ストリーム符号化方式

    佐野 健太郎, 片平 和也, 山本 悟

    電子情報通信学会技術研究報告. CPSY, コンピュータシステム 110 (361) 111-116 2011年1月10日

    出版者・発行元:一般社団法人電子情報通信学会

    ISSN:0913-5685

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    本稿ではストリーム計算におけるメモリ帯域向上を目的とした浮動小数点データ圧縮・展開ハードウェアのための複数データストリーム符号化方式を提案する。複数のデータストリームを並列に圧縮し展開器に送信する場合、計算において必要となる複数のデータを同時に展開する必要がある。しかしながら、圧縮器と展開器の間は単一の通信路またはメモリにより接続されるため、各ストリームの圧縮率に差がある場合、複数ストリームを同期して圧縮・展開するためには圧縮率の低いデータストリームを優先して送信する必要がある。提案する符号化方式では、圧縮データに追加の情報を付加せずに、圧縮率の異なる複数のストリームを同期して展開可能とする。この符号化を実現するためのハードウェア機構を示した上で、そのソフトウェアエミュレーションにより、提案符号化方式の動作検証と、送信データを一時的に溜めておくFIFOの必要サイズに関する評価を行う。

  64. 研究展望,CFDからCFCへのパラダイムシフト 招待有り 査読有り

    山本悟

    日本機械学会論文集B編 77 (774) 195-204 2011年

    出版者・発行元:日本機械学会

    DOI: 10.1299/kikaib.77.195  

    ISSN:0387-5016

  65. ターボ機械・エネルギー機器に関する先端マルチフィジックスシミュレーション,非平衡凝縮・超臨界流体の数値解法をその応用 招待有り 査読有り

    山本悟

    ターボ機械 657-666 2010年11月

    出版者・発行元:ターボ機械協会

  66. 0601 フランジ構造の改良による蒸気タービン部分流入段の性能向上に関する研究(OS6-1 流体機械のCFD解析最前線,オーガナイズドセッション)

    高田 真司, 笹尾 泰洋, 山本 悟

    流体工学部門講演会講演論文集 2010 181-182 2010年10月29日

    出版者・発行元:一般社団法人日本機械学会

    ISSN:1348-2882

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    In the partial admission stage of steam turbines, a flange is placed to separate the nozzle box. The flange makes a large wake which causes the partial admission loss and the ventilation loss. Additionally, it causes a rotor lift oscillation which gives an extra stress to rotors. This paper presents a numerical study of unsteady flows in a partial admission stage. Seven cases with a different flange thickness were simulated. Thicker flanges resulted in better total efficiencies.

  67. 0604 排気段落不均一流出条件を考慮したタービン排気室性能のCFD解析(OS6-1 流体機械のCFD解析最前線,オーガナイズドセッション)

    田沼 唯士, 新関 良樹, 笹尾 泰洋, 渋川 直紀, 山本 悟

    流体工学部門講演会講演論文集 2010 187-188 2010年10月29日

    出版者・発行元:一般社団法人日本機械学会

    ISSN:1348-2882

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    Low pressure exhaust hood is one of the important parts in steam turbines, since the aerodynamic loss of exhaust hoods is nearly the same level of the loss of stator and rotor blading in low pressure steam turbines and there seems to be not little room remained for the enhancement of steam turbine efficiency. This paper presents the result of exhaust hood CFD analyses using last stage exit velocity distributions measured in the real scale development steam turbine as the inlet boundary condition to improve the accuracy of the CFD analysis.

  68. 0603 超音速ノズルを通る超臨界二酸化炭素の数値シミュレーション(OS6-1 流体機械のCFD解析最前線,オーガナイズドセッション)

    阿南 良, 古澤 卓, 山本 悟

    流体工学部門講演会講演論文集 2010 185-186 2010年10月29日

    出版者・発行元:一般社団法人日本機械学会

    ISSN:1348-2882

    詳細を見る 詳細を閉じる

    Our research group has proposed a numerical method for supercritical fluids; Supercritical-Fluid Simulator(SFS). In this paper, supercritical carbon dioxide flows impacting on a flat plate through supersonic nozzle are calculated using SFS and the flow features changing inlet pressure, inlet temperature and the distance to the flat plate are comparatively investigated. Especially, it is noted that the density in the nozzle is rapidly changed and is deeply dependent to the inlet boundary conditions.

  69. 0602 実機規模蒸気タービン多段静動翼列の非定常流動解析(OS6-1 流体機械のCFD解析最前線,オーガナイズドセッション)

    三宅 哲, 加藤 寛人, 笹尾 泰洋, 山本 悟

    流体工学部門講演会講演論文集 2010 183-184 2010年10月29日

    出版者・発行元:一般社団法人日本機械学会

    ISSN:1348-2882

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    Unsteady 3-D flows through two-stage stator-rotor cascade channels in two steam turbine models developed by Mitsubishi Heavy Industry (MHI) are numerically investigated. In low pressure steam turbine cascades, steam flows generate water droplets mainly due to homogeneous nucleation. The mass generation rate for water droplets is modeled as a sum of the mass generation rate of critical-sized nucleus and the growth rate of a water droplet based on the classical condensation theory. The total pressure, the static pressure, and the yaw angle in span-wise directions obtained by the 3-D calculations are compared with the experimental data.

  70. A-14 湿り蒸気を用いたタービン試験とその非定常数値解析(蒸気タービン,一般講演)

    笹尾 泰洋, 加藤 寛人, 山本 悟

    ガスタービン定期講演会講演論文集 (38) 119-122 2010年10月20日

    出版者・発行元:公益社団法人日本ガスタービン学会

    ISSN:0919-1941

    詳細を見る 詳細を閉じる

    Unsteady 3-D flows through two-stage stator-rotor cascade channels in a model turbine are numerically investigated. Compressible Nervier-Stokes equations are solved by the fourth-order compact MUSCL TVD scheme, Roe's approximate Riemann solver, and the LU-SGS scheme. The SST-model is used for evaluating the eddy-viscosity. Condensate mass fractions, pressure distributions, and total pressure losses obtained by the 3-D calculations are compared with each other and compared with the experimental data. Finally the output and the total-total efficiency ratios in the model turbine are numerically predicted.

  71. メモリ帯域向上のための浮動小数点データストリームロスレス圧縮ハードウェア

    佐野 健太郎, 片平 和也, 山本 悟

    電子情報通信学会技術研究報告. RECONF, リコンフィギャラブルシステム : IEICE technical report 110 (204) 37-42 2010年9月9日

    出版者・発行元:一般社団法人電子情報通信学会

    ISSN:0913-5685

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    本稿では格子ボルツマン法(LBM)アクセラレータの実効メモリ帯域を向上させるための、浮動小数点データストリームのハードウェアロスレス圧縮器について述べる。1次元の多項式予測に基づく圧縮アルゴリズムが高スループットハードウェア設計に適することと、回路面積の点で有利な整数演算による多項式予測でも浮動小数点演算による多項式予測に匹敵する圧縮性能を達成し得ることを示す。ALTERA Stratix III FPGAを用いた試作実装により、圧縮率、動作周波数、及び回路面積を評価する。実装した圧縮器は、多項式予測器の次数に応じてStratix In FPGAのAdaPtive LUTの0.15%から0.23%のみを消費し、また、95MHZから174MHzの動作周波数が得られた。本圧縮器は2次元LBM計算の単精度浮動小数点データに対して3.5倍の圧縮率を達成する。これは、データをストリームとして読み書きする場合にメモリ帯域を3.5倍に増加可能なことを意味する。

  72. 複数FPGA上で動作するスケーラブルアレイプロセッサのためのGALS設計

    王 陸洲, 佐野 健太郎, 山本 悟

    電子情報通信学会技術研究報告. RECONF, リコンフィギャラブルシステム : IEICE technical report 110 (32) 69-74 2010年5月6日

    出版者・発行元:一般社団法人電子情報通信学会

    ISSN:0913-5685

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    我々はシステムの規模に対しスケーラブルな高性能差分法計算を実現するため、シストリック計算メモリアーキテクチャを提案している。本アーキテクチャは完全並列に計算を実行可能なアレイ構造を持ち、多数のFPGAを用いることにより、ハードウェア資源に比例したスケーラブルな計算性能を実現する。しかし、現実問題として、多数のFPGAを用いる場合、必然的に異なる複数のクロックドメインを扱うことになり、広域非同期局所同期(GALS)設計が不可欠である。本論文では、異なるクロックドメイン間での非同期通信を可能とし、データ同期を保証する差分法専用計算機のためのGALS設計を提案する。ALTERA社のStratix III FPGAを用いて試作実装を行い、提案するGALS設計のオーバーヘッドは動作周波数とハードウェア資源消費の点において十分に小さく、また、必要最低限のストールしか発生しないことから、本計算機が持つ本来のスケーラビリティは損なわれないことを明らかにする。

  73. 小特集:「マルチフィジックスCFD/EFDの最前線」巻頭言 招待有り 査読有り

    山本悟

    日本機械学会論文集B編 764 (765) 711-711 2010年5月

    出版者・発行元:日本機械学会

    DOI: 10.1299/kikaib.76.765_711  

    ISSN:0387-5016

  74. FPGAによるHPCのためのストリーム計算に関する一検討2次元ヤコビ法のためのスケーラブルパイプラインモジュールの設計と評価

    佐野 健太郎, 初田 義明, 大坪 靖周, 山本 悟

    電子情報通信学会技術研究報告. RECONF, リコンフィギャラブルシステム : IEICE technical report 109 (198) 113-118 2009年9月10日

    出版者・発行元:一般社団法人電子情報通信学会

    ISSN:0913-5685

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    近年、半導体プロセスの微細化に伴い、演算器の性能よりもメモリ帯域が実効性能を決定する主な要因になりつつある。このような状況に対し、演算密度を高めてメモリ参照あたりの実効性能を向上させるストリーム計算が注目されている。本研究では、問題に特化した専用のストリーム計算機をFPGAを用いて構築し、演算器の高い稼働率を維持したまま複数のFPGAによりスケーラブルな性能が得られるHPCシステムの実現を目指している。本発表では最も簡単なステンシル計算の一つであるヤコビ法に基づく計算に対し、ストリーム計算のためのパイプラインモジュールの設計と評価について述べる。

  75. RC-011 差分法専用計算機におけるFPGA間時分割通信機構の遅延評価(ハードウェア・アーキテクチャ,査読付き論文)

    王 陸洲, 佐野 健太郎, 初田 義明, 飯塚 尊則, 山本 悟

    情報科学技術フォーラム講演論文集 8 (1) 189-196 2009年8月20日

    出版者・発行元:FIT(電子情報通信学会・情報処理学会)運営委員会

  76. 蒸気タービン翼列における湿り蒸気流れの数値解法の現状 招待有り 査読有り

    山本悟

    ターボ機械 2009年4月

  77. Finite-Difference Method for Heat Conduction Equation and Excel Calculation, Special Issue: Heat Transfer; Combustion and Drying 招待有り 査読有り

    Satoru Yamamoto

    Journal of the Technical Association of Refractories 28 (4) 239-244 2008年12月

  78. 高性能差分法計算のためのFPGAアレイにおけるFPGA間通信機構の検討

    王 陸洲, 佐野 健太郎, 初田 義明, 山本 悟

    電子情報通信学会技術研究報告. RECONF, リコンフィギャラブルシステム : IEICE technical report 108 (300) 45-48 2008年11月10日

    出版者・発行元:一般社団法人電子情報通信学会

    ISSN:0913-5685

    詳細を見る 詳細を閉じる

    本研究では,差分法を高速に計算できるアレイ型専用計算機を提案している.本計算機は計算要素(PE)のアレイ構造により,PE数に比例した計算性能を持つ.現在,高性能計算を実現するために,大規模アレイを複数のFPGAからなるFPGAアレイにより実装することを検討している.これまでの調査の結果,FPGAアレイに実装される専用計算機の性能は隣接FPGA間のI/O帯域により制約される可能性があることが明らかとなった.本論文では,実際の計算ではFPGA間に要求される帯域を十分に小さくできることを示し,これを実現するFPGA間通信機構について検討する.

  79. A-6 蒸気タービン多段翼列を通る非定常湿り蒸気流れの数値解析(空力I,一般講演)

    笹尾 泰洋, 山本 悟, 皐月 浩史, 大山 宏治, 石坂 浩一

    ガスタービン定期講演会講演論文集 (36) 47-48 2008年10月1日

    出版者・発行元:公益社団法人日本ガスタービン学会

    ISSN:0919-1941

    詳細を見る 詳細を閉じる

    Unsteady 3-D flows through two-stage stator-rotor cascade channels in the steam turbine developed by Mitsubishi Heavy Industry(MHI) are numerically investigated. The mass generation rate for water droplets is formed as a sum of the mass generation rate of critical-sized nucleus and the growth rate of a water droplet based on the classical condensation theory. Wetness due to condensation, pressure distributions, and total pressure losses obtained by the 3-D calculations are compared with each other and compared with the experimental data. Also flow distributions of yaw and pitch angle in span-wise direction at the outlet of stators and rotors are compared with the experiments.

  80. A-25 部分流入を考慮したタービン初段静動翼列全流路流れの数値解析(空力VI,一般講演)

    笹尾 泰洋, 門間 和弘, 山本 悟, 田沼 唯士

    ガスタービン定期講演会講演論文集 (36) 155-158 2008年10月1日

    出版者・発行元:公益社団法人日本ガスタービン学会

    ISSN:0919-1941

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    Unsteady flows through whole nozzle-rotor cascade channels in partial admission stage are numerically investigated using the high-resolution finite-difference method developed by our group. Compressible Navier-Stokes equations are solved by the fourth-order compact MUSCL TVD scheme, Roe's approximate Riemann solver, and the LU-SGS scheme. The SST-model is used for evaluating the eddy-viscosity. As numerical examples, unsteady two-dimensional flows in a partial admission stage of steam turbine are first calculated. 108 nozzle passages with two blockages and 60 rotor passages are simultaneously calculated. The effect of the blockage to the lift of rotors is numerically investigated. Also the efficiency of the partial admission stage changing the number of blockages and the number of nozzles is parametrically predicted.

  81. RC-003 複数FPGAによるアレイ型差分法専用計算機のためのFPGA間通信帯域評価(ハードウェア・アーキテクチャ,査読付き論文)

    王 陸洲, 佐野 健太郎, 初田 義明, 山本 悟

    情報科学技術フォーラム講演論文集 7 (1) 25-28 2008年8月20日

    出版者・発行元:FIT(電子情報通信学会・情報処理学会)運営委員会

  82. アレイ構造に基づく差分法専用計算機のFPGA実装

    佐野 健太郎, 王 陸洲, 初田 義明, 山本 悟

    計算工学講演会論文集 13 (2) 683-686 2008年5月19日

    出版者・発行元:日本計算工学会

    ISSN:1342-145X

  83. マルチフィジックスCFDシミュレーションの産業応用,タービン多段静動翼列を通る湿り蒸気流れの大規模計算 招待有り 査読有り

    山本悟

    日本流体力学会誌「ながれ」 27 121-126 2008年4月

    DOI: 10.11426/nagare1982.27.121  

  84. 518 任意物質の熱流動が計算できる前処理型数値解法の開発(2)(OS5-3 機能性流体工学の先端融合化,OS5 機能性流体工学の先端融合化,オーガナイズドセッション)

    古澤 卓, 山本 悟

    流体工学部門講演会講演論文集 2007 "518-1"-"518-4" 2007年11月17日

    出版者・発行元:一般社団法人日本機械学会

    ISSN:1348-2882

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    This paper presents the capability of the supercritical-fluids simulator (SFS) developed by us to simulate thermal convections of arbitrary substance in arbitrary conditions. In SFS, a numerical method based on the preconditioning method coupled with the PROPATH database is used. The method enables us to calculate not only thermal convections of supercritical fluids but also those of arbitrary substances in gas and liquid phases. As numerical examples, carbon-dioxide, water, nitrogen, methane and helium in a square cavity in several conditions are calculated using SFS and the calculated results are compared with each other and some of them are compared with the existing numerical results.

  85. 熱伝導方程式の差分解法とExcelを用いた計算 招待有り 査読有り

    山本悟

    耐火物技術協会誌 59 (9) 460-466 2007年9月

    出版者・発行元:耐火物技術協会

    ISSN:0039-8993

  86. 機械工学年鑑, 流体工学, タービン流れ 招待有り 査読有り

    山本悟

    日本機械学会誌 27-28 2007年8月

    出版者・発行元:日本機械学会

  87. 数値タービンのスーパーコンピューティング 招待有り 査読有り

    山本悟, 笹尾泰洋

    ターボ機械協会誌 2006年9月

  88. 3102 多段タービン翼列を通る湿りを伴う干渉流れの数値シミュレーション(OS-31A,OS-31 CFDの工学的応用)

    笹尾 泰洋, 山本 悟, 石坂 浩一, 大山 宏治

    計算力学講演会講演論文集 2005 (18) 197-198 2005年11月17日

    出版者・発行元:一般社団法人日本機械学会

    ISSN:1348-026X

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    Wet-steam flows through steam-turbine cascades in a multiple stage are numerically simulated. As numerical examples, wet-steam flows through a single cascade channel developed by Bakhtar is calculated and the calculated results are compared with the experiments, and wet-steam flows through turbine cascades in multi stage developed by Mitsubishi Heavy Industries are calculated assuming unsteady states. Finally, the effect of the wetness in the stages are numerically predicted. Fundamental equations contain conservation laws of water vapor, water liquid, the number density of nucleus, momentum equations, and the energy equation. The SST turbulence model is employed to predict the eddy viscosity. The classical condensation theory is used for modeling homogeneous and heterogeneous condensations. These equations are solved by the fourth-order compact MUSCL TVD scheme and LU-SGS scheme.

  89. ガスタービンの流体力学解析,数値計算 招待有り 査読有り

    山本悟

    第11回ガスタービン教育シンポジウム資料 2005年7月

    出版者・発行元:日本ガスタービン学会

  90. ターボ機械翼列を通る湿り空気・蒸気の乱流解析(OS23c 相変化・超臨界流体の計算力学)

    笹尾 泰洋, 山本 悟

    計算力学講演会講演論文集 2004 (17) 159-160 2004年11月17日

    出版者・発行元:一般社団法人日本機械学会

    ISSN:1348-026X

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    In this study, transonic humid-air and wet-steam turbulent flows through a steam turbine cascade channel are calculated. Transonic condensate flows in turbomachinery are numerically predicted by using the high-resolution method developed by our group. Fundamental equations consist of conservation laws of mixed gas, water vapor, water liquid, and the number density of water droplets, coupled with the momentum equations and the energy equation. The classical condensation theory is employed for modeling homogeneous nucleation and non-equilibrium condensation. These equations are solved by a high-order high-resolution finite-difference method based on the fourth-order compact MUSCL TVD scheme, Roe's approximate Riemann solver, and the LU-SGS scheme. SST model is used for evaluating eddy-viscosity.

  91. ガスタービンに関連するCFD(数値流体力学)解析の現状,ガスタービンCFD技術の現状と将来動向 招待有り 査読有り

    山本 悟

    日本ガスタービン学会誌 32 (4) 239-302,図巻頭4p 2004年7月

    出版者・発行元:日本ガスタービン学会

    ISSN:0387-4168

  92. 蒸気タービンの湿り蒸気の影響低減技術 招待有り 査読有り

    田沼唯士, 長尾進一郎, 山本悟

    ターボ機械 31 (8) 453-458 2003年8月

    出版者・発行元:Turbomachinery Society of Japan

    DOI: 10.11458/tsj1973.31.453  

    ISSN:0385-8839

  93. Gas Turbine Technology in Japan, R&D of CFD Code for Compressible Interdisciplinary Flows 招待有り 査読有り

    Satoru Yamamoto

    Bulletin of GTSJ 2003年4月

  94. 大気環境中のデルタ翼周りに発生する凝縮渦(飛行機雲)の数値計算

    山本 悟, 申 炳録

    可視化情報学会誌 = Journal of the Visualization Society of Japan 22 447-450 2002年7月1日

    出版者・発行元:可視化情報学会

    ISSN:0916-4731

  95. 複雑系流体解析コードの研究開発(ガスタービンから相変化工学まで) 招待有り 査読有り

    山本 悟

    日本ガスタービン学会誌 30 (4) 2002年7月

  96. 航空分野からの研究発表を概観して 招待有り 査読有り

    山本 悟

    日本数値流体力学会誌 10 (1) 15-17 2002年1月

  97. 419 三次元大規模渦中における凝縮現象の数値シミュレーション(O.S.4-5 凝縮相を伴う圧縮性流れ)(O.S.4 圧縮性流れ・衝撃波)

    山本 悟, 申 炳録

    流体工学部門講演会講演論文集 2001 59-59 2001年9月28日

    出版者・発行元:一般社団法人日本機械学会

    ISSN:1348-2882

  98. 420 凝縮を伴う非定常蒸気タービン翼列流れの数値シミュレーション(O.S.4-5 凝縮相を伴う圧縮性流れ)(O.S.4 圧縮性流れ・衝撃波)

    山本 悟, 大友 宏之, 田沼 唯士

    流体工学部門講演会講演論文集 2001 60-60 2001年9月28日

    出版者・発行元:一般社団法人日本機械学会

    ISSN:1348-2882

  99. 412 大気環境中における遷音速翼周り流れの数値シミュレーション(O.S.4-3 圧縮性流体の数値解析)(O.S.4 圧縮性流れ・衝撃波)

    佐藤 大悟, 山本 悟, 申 炳録

    流体工学部門講演会講演論文集 2001 52-52 2001年9月28日

    出版者・発行元:一般社団法人日本機械学会

    ISSN:1348-2882

  100. CFD特集-2, タービン翼列内流れの非定常解析 招待有り 査読有り

    山本 悟

    ターボ機械 28 (12) 28-34 2000年5月

  101. 熱流体の数値計算, 数値解析手法 招待有り 査読有り

    山本 悟

    日本ガスタービン学会誌 26 (102) 3-9 1998年9月

  102. ガスタービン冷却静翼の空力特性

    渋川 直紀, 川崎 榮, 田沼 唯士, 山本 悟

    ガスタービン定期講演会講演論文集 25 25-30 1997年5月15日

    出版者・発行元:公益社団法人日本ガスタービン学会

    ISSN:0919-1941

  103. ナビエ・ストークス方程式による流れの数値シミュレーション, CFDの基礎(II), 反応流のモデルと計算 招待有り 査読有り

    山本 悟

    日本数値流体力学会第1,2回講習会資料 125-212 1994年8月

  104. OREXまわりの非平衡流れの数値計算(第12回航空機計算空気力学シンポジウム論文集 特別企画/極超音速流のCFDワークショップ)

    長友 英夫, 山本 悟, 大宮司 久明

    航空宇宙技術研究所特別資料 26 19-22 1994年

    出版者・発行元:独立行政法人航空宇宙技術研究所

    ISSN:0289-260X

  105. B-13 非定常遷音速翼列流れの高解像差分スキーム(非定常空力)

    袁 新, 山本 悟, 大宮司 久明

    ガスタービン秋季講演会講演論文集 (5) 217-224 1993年9月27日

    出版者・発行元:公益社団法人日本ガスタービン学会

    ISSN:0919-1968

  106. 最近のターボ機械流れの解析技術 招待有り 査読有り

    山本 悟, 大宮司 久明

    ターボ機械 19 (11) 56-62 1991年11月

    DOI: 10.11458/tsj1973.19.750  

  107. 数値シミュレーション技術(流れの数値解析法) 招待有り 査読有り

    大宮司 久明, 山本 悟

    日本ガスタービン学会誌 17 (65) 4-10 1989年6月

    出版者・発行元:公益社団法人日本ガスタービン学会

    ISSN:0387-4168

︎全件表示 ︎最初の5件までを表示

書籍等出版物 9

  1. Introduction to Three-dimensional Incompressible CFD

    Satoru Yamamoto

    ResearchGate 2020年1月

  2. Mathematical Modelling and Computation for Rapid Expansion of Supercritical Solutions, Supercritical and Other High-pressure Solvent Systems (ed. by Thomas M. Attard and Andrew J. Hunt)

    Royal Society of Chemistry 2018年8月

    DOI: 10.1039/9781788013543-FP001  

  3. Introduction to Multiphysics CFD

    Satoru Yamamoto

    ResearchGate 2018年4月

    詳細を見る 詳細を閉じる

    Online lecture note: Introduction to Multiphysics CFD

  4. Introduction to Mathematical Modeling and Computation

    Satoru Yamamoto

    ResearchGate 2018年4月

    詳細を見る 詳細を閉じる

    Online lecture note: Introduction to Mathematical Modeling and Computation

  5. ガスタービン工学

    山本悟

    日本ガスタービン学会 2013年8月

  6. 大学院情報理工学3 計算力学

    山本悟

    講談社サイエンティフィク 2000年3月

  7. Special Issue Dedicated to Professor Hisaaki Daiguji on the Occasion of His Retirement from Tohoku University, Computational Fluid Dynamics Journal

    Mohamed Hafez, Satoru Yamamoto

    1999年

  8. 乱流の数値流体力学

    山本 悟, 大宮司 久明

    1998年1月

  9. 衝撃波ハンドブック

    大宮司久明, 山本悟

    1995年12月

︎全件表示 ︎最初の5件までを表示

講演・口頭発表等 58

  1. デジタルツイン数値タービンの研究開発 招待有り

    山本悟

    日本ガスタービン学会第52回ガスタービンセミナー 2024年1月30日

  2. デジタルツイン数値タービンへの道 招待有り

    山本悟

    日本機械学会2023年度年次大会 2023年9月5日

  3. 臨界点をまたぐ超臨界流体のシミュレーション技術 招待有り

    山本悟

    VINAS Industry Seminar「カーボンニュートラル・超臨界CO2・水素利用技術セミナー」 2021年3月9日

  4. Modeling and Simulation of Thermophysical Flows with Nonequilibrium Condensation 国際会議 招待有り

    14th International Symposium on Experimental and Computational Aerothermodynamics of Internal Flows 2019年8月8日

  5. 超臨界CO2流れのシミュレーション技術 招待有り

    山本 悟

    日本ガスタービン学会ガスタービンセミナー 2019年1月25日

  6. Steam Turbine Tutrial: A Free Energy Perspective on Homogneous Nucleation Model 国際会議 招待有り

    ASME 2018 Turbo Expo 2018年6月14日

  7. 蒸気タービンを通過する湿り蒸気流れのCFD 招待有り

    ターボ機械協会第122回セミナー「蒸気タービンのCFD」 2015年11月6日

  8. 数値タービンならびに超臨界流体シミュレータ(SFS)の研究開発 招待有り

    VINAS User Conference 2015 2015年10月15日

  9. マルチフィジックスCFDの産業応用 招待有り

    山本悟

    日本機械学会2013年次大会ワークショップマルチフィジックスCFDの産業応用「CFDの産業活用における方向性」 2013年9月9日

  10. Numerical Turbine System(NTS) and the Parallel Computation 国際会議 招待有り

    Satoru Yamamoto, Yasuhiro Sasao

    17th Workshop on Sustained Simulation Performance 2013年3月13日

  11. Simullation of Thermophysical Flows with Non-equilibrium Condensation 国際会議 招待有り

    Satoru Yamamoto, Satoshi Miyake, Takashi Furusawa, Ryo Anan

    Cambridge Baumann Centenary Conference on Wet Steam Flows 2012年9月10日

  12. Simulation of Thermophysical Flows 国際会議 招待有り

    Satoru Yamamoto, Takashi Furusawa

    Eighth KSME-JSME Thermal and Fluids Engineering Conference 2012年3月30日

  13. Preconditioning Method of Simulating Gas, Liquid, and Supercritical-fluid Flows with Phase Change 国際会議 招待有り

    2010 Korea-Japan CFD Workshop 2010年11月19日

  14. 蒸気タービン湿り蒸気流れの大規模シミュレーション 招待有り

    日本機械学会2010年度年次大会先端技術フォーラム「流体機械・エネルギー機器の研究開発における先端マルチフィジックスシミュレーション」 2010年9月6日

  15. Numerical Method of Simulating Supercritical-fluid Flows across Critical Point 国際会議 招待有り

    2nd International Workshops on Advances in Computational Mechanics 2010年3月31日

  16. Current Status of CFD Codes: IB Solver, Numerical Turbine(NT), and Supercritical-fluids Simulator(SFS) 国際会議 招待有り

    11th Teraflop Workshop 2009年10月19日

  17. 楽しい数値計算-数値流体力学・計算数理科学 招待有り

    岩手大学特別講義 2009年7月24日

  18. 数値タービンと超臨界流体シミュレータ 招待有り

    第19回東北混相流研究会 2007年6月8日

  19. Supercomputing of Flows with Complex Physics and the Future Progress 国際会議 招待有り

    5th Teraflop Workshop, Sendai 2006年11月21日

  20. Numerical Solution of the Rayleigh-Benard Convection at a Supercritical State 国際会議 招待有り

    Satoru Yamamoto, Atsushi Ito, Akira Ishigame

    ISHR&ICSTR2006 2006年8月6日

  21. Mathematical Modeling and Numerical Schemes for Condensate Flows and Near-critical Fluids 国際会議 招待有り

    19th Symposium of Computational Fluid Dynamics, Japan-Korea CFD Seminar 2005年12月14日

  22. Numerical method for transonic flows with nonequilibrium condensation 国際会議 招待有り

    Xi'an Jiaotang University, Invited Lectures 2005年12月4日

  23. OS「CFDの工学的応用」 相変化を伴う流れ解析法の構築と実用化 招待有り

    日本機械学会計算力学講演会 2005年11月19日

  24. 計算数理科学-その基盤としてのCFD- 招待有り

    特別講義、大阪大学 2005年7月22日

  25. Numerical Method for Multiphase with Phase Transition and Turbulence 国際会議 招待有り

    IWACOM 2004年11月

  26. High-order Scheme 国際会議 招待有り

    5th Asian Computational Fluid Dynamics Conference 2003年10月26日

  27. 8th International Symposium on Gas-Liquid Two Phase Flows 国際会議

    ASME Fluid Engineering Division Summer Meeting, 8th International Symposium on Gas-Liquid Two Phase Flows 2003年7月7日

  28. General Session II 国際会議

    3rd Int. Symp. on Advanced Energy Conversion Systems and Related Technologies 2001年12月15日

  29. Numerical Method of Steady and Unsteady Compressible Interdisciplinary Flow Problems 国際会議

    Japan-Russia Int. Workshop on Turbulence, Instabilities and Parallel Computing 2001年10月22日

  30. Onset of Condensation in Vortical Flow over Sharp-edged Delta Wing 国際会議

    AIAA 15th CFD Conference 2001年6月

  31. CFD技術、タービン翼列内流れの非定常解析 招待有り

    ターボ機械協会第26回講習会 2001年3月9日

  32. NUMERICAL STUDY OF NONEQUILIBRIUM CONDENSATION IN UNSTEADY TRANSONIC VISCOUS FLOW PROBLEM 国際会議

    ECCOMAS 2000 2000年9月

  33. NUMERICAL STUDY OF NONEQUILIBRIUM CONDENSATION IN UNSTEADY TRANSONIC VISCOUS FLOW PROBLEM 国際会議

    AIAA FLUIDS 2000 Conference and Exhibit 2000年6月

  34. NUMER ICAL STUDY OF UNSTEADY GAS AND STEAM TURBINE CASCADE FLOWS 国際会議

    International Gas Turbine Congress 1999 1999年11月

  35. Numerical Study of Unsteady 3D Hypersonic Shock Interference Flows 国際会議

    8th ISCFD'99 1999年9月

  36. Numerical Investigation of Nonequilibrium Condensation Effect around 3-D Transonic Wing in Moist Air 国際会議

    16th International Conference on Numerical Methods in Fluid Dynamics 1998年7月

  37. Numerical Study of Unsteady Shock/Boundary-Layer Interaction Induced by A Blunt Fin 国際会議

    29th AIAA Fluid Dynamics Conference 1998年6月

  38. TVD法, 反応流 招待有り

    日本航空宇宙学会北部支部, CFD講習会 1997年10月2日

  39. Numerical Investigation of Shock/Vortex Interaction in Hypersonic Thermochemical Nonequilibrium Flow 国際会議

    32nd Thermophysics Conference 1997年6月

  40. ガスタービン翼列流れにおける衝撃波/渦干渉の数値計算法 招待有り

    日本航空宇宙学会第29期年会講演会 1997年4月8日

  41. NUMERICAL INVESTIGATION OF STRONGLY NON-LINEAR TRANSONIC FLOW PROBLEMS AROUND THE AIRFOIL 国際会議

    20th Congress of the International Council of the Aeronautical Science 1996年9月

  42. Accurate Schemes in CFD, Higher-Order Shock-Vortex Capturing for Unsteady Internal and External Flows 国際会議 招待有り

    14th NAL Symposium on Aircraft Computational Aerodynamics 1996年6月6日

  43. SHOCK-VORTEX CAPTURING METHOD FOR STRONGLY UNSTEADY FLOW PROBLEMS 国際会議

    15th International Conference on Numerical Methods in Fluid Dynamics 1996年6月

  44. Structure of Bow Shock and Compression Wave Interactions in Unsteady Hypersonic Shock/Shock Interference Flow 国際会議

    1st AIAA Theoretical Fluid Mechanics Meeting 1996年6月

  45. 東北大学における航空宇宙関連の研究の現状 招待有り

    岩手県宇宙航空開発推進協議会主催航空宇宙開発セミナー 1995年11月22日

  46. 流束分離とTVD法 招待有り

    日本航空宇宙学会北部支部、圧縮性流れのCFD講習会 1995年10月14日

  47. 非定常圧縮性流れの数値解析法(亜音速から極超音速まで)

    東京大学大学院航空宇宙工学専攻1995年Aerospace Propulsion Seminar 1995年9月22日

  48. 非定常衝撃波/渦干渉流れの高解像差分スキームとそのターボ機械への応用

    1995 ターボ機械の空力セミナー in 盛岡 1995年8月20日

  49. ナビエ・ストークス方程式による流れのシミュレーション、CFDの基礎(II)、反応流のモデルと計算 招待有り

    日本数値流体力学会第1,2回講習会 1994年8月29日

  50. HIGHER-ORDER NUMERICAL SIMULATION OF UNSTEADY SHOCK/VORTEX INTERATIONS 国際会議

    25th AIAA Fluid Dynamics Conference 1994年6月

  51. 再突入の極超音速流、極超音速熱・化学非平衡流の数値解法 招待有り

    日本機械学会第71期通常総会、先端技術フォーラム 1994年3月29日

  52. スタンフォード大学での留学生活とその周辺の環境 招待有り

    日本機械学会東北支部技術懇談会 1993年6月18日

  53. A HIGHER-ORDER ACCURATE NAVIER-STOKES SOLVER FOR TRANSONIC AND SUPERSONIC FLOWS IN TURBOMACHINERY 国際会議

    AIAA/SAE/ASME/ASEE 28th Joint Propulsion Conference and Exhibit 1992年7月6日

  54. HIGHER-ORDER-ACCURATE UPWIND SCHEMES FOR SOLVING THE COMPRESIBLE EULER AND NAVIER-STOKES EQUATIONS 国際会議

    Fourth International Symposium on CFD 1991年9月

  55. UNSTEADY NAVIER-STOKES SIMULATION OF TURBULENT FLOWS THROUGH A SUPERSONIC COMPRESSOR CASCADE 国際会議

    First ASME-JSME Fluids Engineering Conference 1991年6月

  56. Numerical Simulation of Unsteady Turbulent Flow through Transonic and Supersonic Cascades 国際会議

    12th International Conference on Numerical Methods in Fluid Dynamics 1990年7月

  57. A Streamwise TVD Scheme for Solving the Compressible Euler Equations 国際会議

    Third International Conference on Hyperbolic Problems 1990年6月

  58. A NUMERICAL METHOD FOR SOLVING THE UNSTEADY COMPRESSIBLE NAVIER-STOKES EQUATIONS 国際会議

    International Symposium on Computational Fluid Dynamics 1989年8月

︎全件表示 ︎最初の5件までを表示

メディア報道 18

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    HPCwire JAPAN

    2023年6月30日

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    日本経済新聞 電子版

    2023年6月30日

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    東北大学 プレスリリース

    2023年6月30日

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    MONOist https://monoist.atmarkit.co.jp/mn/articles/2110/27/news045.html

    2021年10月27日

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    Yahoo ニュース https://news.yahoo.co.jp/articles/d7e90ba92ced94cb0b97a810875933ca4c43cc51

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    ZDNet Japan https://japan.zdnet.com/article/35178217/

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    モーターファン https://motor-fan.jp/tech/article/6193/

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