Details of the Researcher

PHOTO

Akihiro Hayakawa
Section
Institute of Fluid Science
Job title
Associate Professor
Degree

  • Dr. Eng. (Kyushu University)

Professional Memberships 4

  • 日本航空宇宙学会

  • 自動車技術会

  • 日本機械学会

  • 日本燃焼学会

Research Interests 2

  • Combustion

  • Reactive Gas Dynamics

Research Areas 1

  • Manufacturing technology (mechanical, electrical/electronic, chemical engineering) / Thermal engineering /

Awards 10

  1. 日本燃焼学会論文賞

    2020/12　日本燃焼学会　Development of a wide range-operable, rich-lean low-NOx combustor for NH3 fuel gas-turbine power generation

  2. 日本燃焼学会論文賞

    2019/12　Science and Technology of Ammonia Combustion

  3. Best Presentation Award for Young Researcher

    2019/11　Product Gas Characteristics of Strain and Swirl Stabilized Ammonia/air Flames

  4. Certificate of Merit for Thermal Engineering Best Paper

    2018/10　JSME Thermal Engineering Division　Effects of pressure on combustion characteristics of ammonia/air premixed turbulent flames in swirling flows

  5. 日本機械学会奨励賞（研究）

    2018/04　日本機械学会

  6. 日本燃焼学会 ベストプレゼンテーション賞

    2016/11/24　日本燃焼学会

  7. 日本機械学会 熱工学部門 部門一般表彰（講演論文表彰）

    2012/11　日本機械学会熱工学部門

  8. 日本機械学会 三浦賞

    2010/03　日本機械学会

  9. 日本機械学会 若手優秀講演フェロー賞

    2009/04　日本機械学会

  10. 日本機械学会 畠山賞

    2006/03　日本機械学会

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Papers 123

  1. Achieving high flame stability with low NO And Zero N2O and NH3 emissions during liquid ammonia spray combustion with gas turbine combustors

    Ekenechukwu C. Okafor, Osamu Kurata, Hirofumi Yamashita, Norihiko Iki, Takahiro Inoue, Hyun Jo, Masayasu Shimura, Taku Tsujimura, Akihiro Hayakawa, Hideaki Kobayashi

    Proceedings of the Combustion Institute　2024/11

    DOI： 10.1016/j.proci.2024.105340 　

    ISSN： 1540-7489

  2. Visualization of liquid ammonia spray using 2p-SLIPI and comparison of liquid ammonia spray and gaseous ammonia combustion in a swirl combustor at atmospheric pressure Peer-reviewed

    Hirofumi Yamashita, Akihiro Hayakawa, Kohei Oku, Sophie Colson, Gauthier Reibel, Yi-rong Chen, K. D. Kunkuma A. Somarathne, Ekenechukwu C. Okafor, Taku Tsujimura, Shintaro Ito, Masahiro Uchida, Taku Kudo, Hideaki Kobayashi

    Fuel　371　131833　2024/09

    DOI： 10.1016/j.fuel.2024.131833 　

  3. Enhancement of liquid ammonia combustion by a twin fluid atomizer

    Osamu Kurata, Okafor Ekenechukwu Chijioke, Hirofumi Yamashita, Takahiro Inoue, Taku Tsujimura, Norihiko Iki, Akihiro Hayakawa, Hideaki Kobayashi

    International Journal of Gas Turbine, Propulsion and Power Systems　2024/07

    DOI： 10.38036/jgpp.15.4_v15n4tp02 　

    ISSN： 1882-5079

  4. Optimum primary equivalence ratio for rich-lean two-stage combustion of non-premixed ammonia/methane/air and ammonia/hydrogen/air flames in a swirling flow

    Hirofumi Yamashita, Akihiro Hayakawa, Ekenechukwu C. Okafor, Sophie Colson, K. D. Kunkuma A. Somarathne, Taku Tsujimura, Shintaro Ito, Masahiro Uchida, Taku Kudo, Hideaki Kobayashi

    Fuel　368　131598-131598　2024/07

    Publisher: Elsevier BV

    DOI： 10.1016/j.fuel.2024.131598 　

    ISSN： 0016-2361

  5. Emission characteristics of confined non-premixed ammonia–oxygen–nitrogen turbulent jet flames under oxygen-enriched conditions

    Yu Xia, Yuxuan Shen, Kodai Sakai, Daichi Matsumoto, Sophie Colson, Taku Kudo, Akihiro Hayakawa, Hideaki Kobayashi

    Proceedings of the Combustion Institute　40　(1-4)　105704-105704　2024

    Publisher: Elsevier BV

    DOI： 10.1016/j.proci.2024.105704 　

    ISSN： 1540-7489

  6. Towards the development of liquid ammonia/air spray combustion in a gas turbine-like combustor at moderately high pressure

    Kapuruge Don Kunkuma Amila Somarathne, Hirofumi Yamashita, Sophie Colson, Kohei Oku, Keito Honda, Ekenechukwu Chijioke Okafor, Akihiro Hayakawa, Taku Kudo, Hideaki Kobayashi

    Applications in Energy and Combustion Science　16　100215-100215　2023/12

    Publisher: Elsevier BV

    DOI： 10.1016/j.jaecs.2023.100215 　

    ISSN： 2666-352X

  7. Study on the effect of injection temperature and nozzle geometry on the flashing transition of liquid ammonia spray

    Sophie Colson, Hirofumi Yamashita, Kohei Oku, Kapuruge Don Kunkuma Amila Somarathne, Taku Kudo, Akihiro Hayakawa, Hideaki Kobayashi

    Fuel　348　128612-128612　2023/09

    Publisher: Elsevier BV

    DOI： 10.1016/j.fuel.2023.128612 　

    ISSN： 0016-2361

  8. Investigation of bimodal characteristics of the droplet size distribution in condensation spray

    Junnosuke Okajima, Mitsuki Kato, Akihiro Hayakawa, Yuka Iga

    Scientific Reports　13　(1)　2023/07/25

    Publisher: Springer Science and Business Media LLC

    DOI： 10.1038/s41598-023-39087-5 　

    eISSN： 2045-2322

    More details Close

    Abstract To understand the generation process of airborne droplets during exhalation, this study investigates the mechanism of bimodal characteristics of the size distribution of droplets generated in a condensed spray flow. The phase change process in the condensed spray flow was estimated based on the droplet size distribution measured by a phase Doppler particle analyzer and the temperature distribution measured by a thermistor. On the central axis, the size distribution was unimodal in the spray interior. In contrast, bimodality of the size distribution at the outer edge of the spray flow was observed. At the edge of the spray flow, a large temperature gradient was formed. This indicates that condensation actively occurred at the outer edge. For the same reason as outlined above, condensation did not progress at the spray center because of the consumption of water vapor at the outer edge by the condensation, and the droplet diameter did not change significantly. Hence, owing to the difference in the local phase change process between the center and outer edge of the spray, large and small droplets can exist simultaneously in the middle region. As a result, the size distribution of the condensation spray is bimodal.

  9. Nitrogen oxide emissions analyses in ammonia/hydrogen/air premixed swirling flames

    Syed Mashruk, Marina Kovaleva, Ali Alnasif, Cheng Tung Chong, Akihiro Hayakawa, Ekenechukwu C. Okafor, Agustin Valera-Medina

    Energy　260　2022/12/01

    DOI： 10.1016/j.energy.2022.125183 　

    ISSN： 0360-5442

  10. Evolution of N<inf>2</inf>O production at lean combustion condition in NH<inf>3</inf>/H<inf>2</inf>/air premixed swirling flames

    S. Mashruk, E. C. Okafor, M. Kovaleva, A. Alnasif, D. Pugh, A. Hayakawa, A. Valera-Medina

    Combustion and Flame　244　2022/10

    DOI： 10.1016/j.combustflame.2022.112299 　

    ISSN： 0010-2180

    eISSN： 1556-2921

  11. Numerical and experimental study of product gas characteristics in premixed ammonia/methane/air laminar flames stabilised in a stagnation flow

    Marina Kovaleva, Akihiro Hayakawa, Sophie Colson, Ekenechukwu C. Okafor, Taku Kudo, Agustin Valera-Medina, Hideaki Kobayashi

    Fuel Communications　10　100054-100054　2022/03

    Publisher: Elsevier BV

    DOI： 10.1016/j.jfueco.2022.100054 　

    ISSN： 2666-0520

  12. Effects of initial mixture temperature and pressure on laminar burning velocity and Markstein length of ammonia/air premixed laminar flames

    Ryuhei Kanoshima, Akihiro Hayakawa, Takahiro Kudo, Ekenechukwu C. Okafor, Sophie Colson, Akinori Ichikawa, Taku Kudo, Hideaki Kobayashi

    Fuel　310　122149-122149　2022/02

    Publisher: Elsevier BV

    DOI： 10.1016/j.fuel.2021.122149 　

    ISSN： 0016-2361

  13. Measurement of the laminar burning velocity and kinetics study of the importance of the hydrogen recovery mechanism of ammonia/hydrogen/air premixed flames

    Gabriel J. Gotama, Akihiro Hayakawa, Ekenechukwu C. Okafor, Ryuhei Kanoshima, Masao Hayashi, Taku Kudo, Hideaki Kobayashi

    Combustion and Flame　236　111753-111753　2022/02

    Publisher: Elsevier BV

    DOI： 10.1016/j.combustflame.2021.111753 　

    ISSN： 0010-2180

    eISSN： 1556-2921

  14. Quantitative OH concentration measurement using OH(2,0) band bi-directional LIF method for high-pressure and high-temperature symmetrical flames

    Yasuhiro HIGUCHI, Yoshio NUNOME, Satoshi TAKADA, Ryoma YOSHIKAWA, Taku KUDO, Akihiro HAYAKAWA, Hideaki KOBAYASHI

    Journal of Thermal Science and Technology　17　(3)　22-00216　2022

    Publisher: Japan Society of Mechanical Engineers

    DOI： 10.1299/jtst.22-00216 　

    eISSN： 1880-5566

  15. Experimental and Numerical Study of NH3/CH4 Counterflow Premixed and Non-premixed Flames for Various NH3 Mixing Ratios Peer-reviewed

    Sophie Colson, Yuta Hirano, Akihiro Hayakawa, Taku Kudo, Hideaki Kobayashi, Cédric Galizzi, Dany Escudié

    Combustion Science and Technology　193　(16)　2872-2889　2021/12/10

    Publisher: Informa UK Limited

    DOI： 10.1080/00102202.2020.1763326 　

    ISSN： 0010-2202

    eISSN： 1563-521X

  16. Nitrogen Oxides as a By-product of Ammonia/Hydrogen Combustion Regimes Peer-reviewed

    S. Mashruk, M. Kovaleva, C. T. Chong, A. Hayakawa, E. C. Okafor, A. Valera-Medina

    Chemical Engineering Transactions　89　613-618　2021/12

    DOI： 10.3303/CET2189103 　

    eISSN： 2283-9216

  17. Stabilization mechanisms of an ammonia/methane non-premixed jet flame up to liftoff

    Sophie Colson, Manuel Kuhni, Akihiro Hayakawa, Hideaki Kobayashi, Cédric Galizzi, Dany Escudié

    Combustion and Flame　234　111657-111657　2021/12

    Publisher: Elsevier BV

    DOI： 10.1016/j.combustflame.2021.111657 　

    ISSN： 0010-2180

    eISSN： 1556-2921

  18. Laminar Burning Velocity and Markstein Length of CH4/CO2/Air Premixed Flames at Various Equivalence Ratios and CO2 Concentrations Under Elevated Pressure Peer-reviewed

    Willyanto Anggono, Akihiro Hayakawa, Ekenechukwu C. Okafor, Gabriel Jeremy Gotama, Stevan Wongso

    Combustion Science and Technology　193　(14)　2369-2388　2021/10/26

    Publisher: Informa UK Limited

    DOI： 10.1080/00102202.2020.1737032 　

    ISSN： 0010-2202

    eISSN： 1563-521X

  19. Liquid ammonia spray combustion in two-stage micro gas turbine combustors at 0.25 MPa; Relevance of combustion enhancement to flame stability and NOx control

    Ekenechukwu C. Okafor, Osamu Kurata, Hirofumi Yamashita, Takahiro Inoue, Taku Tsujimura, Norihiko Iki, Akihiro Hayakawa, Shintaro Ito, Masahiro Uchida, Hideaki Kobayashi

    Applications in Energy and Combustion Science　7　100038-100038　2021/09

    Publisher: Elsevier BV

    DOI： 10.1016/j.jaecs.2021.100038 　

    ISSN： 2666-352X

  20. Flame stability and emissions characteristics of liquid ammonia spray co-fired with methane in a single stage swirl combustor Peer-reviewed

    Ekenechukwu C. Okafor, Hirofumi Yamashita, Akihiro Hayakawa, K.D. Kunkuma A. Somarathne, Taku Kudo, Taku Tsujimura, Masahiro Uchida, Shintaro Ito, Hideaki Kobayashi

    Fuel　287　119433-119433　2021/03

    DOI： 10.1016/j.fuel.2020.119433 　

    ISSN： 0016-2361

    eISSN： 1873-7153

  21. Start-up process of 50KW-Class gas turbine firing ammonia gas

    Osamu Kurata, Norihiko Iki, Yong Fan, Takayuki Matsunuma, Takahiro Inoue, Taku Tsujimura, Hirohide Furutani, Masato Kawano, Keisuke Arai, Ekenechukwu C. Okafor, Akihiro Hayakawa, Hideaki Kobayashi

    Proceedings of the ASME Turbo Expo　6　2021

    DOI： 10.1115/GT2021-59448 　

  22. Turbulent flame propagation limits of ammonia/methane/air premixed mixture in a constant volume vessel Peer-reviewed

    Genya Hashimoto, Khalid Hadi, Yu Xia, Aainaa Hamid, Nozomu Hashimoto, Akihiro Hayakawa, Hideaki Kobayashi, Osamu Fujita

    Proceedings of the Combustion Institute　38　(4)　5171-5180　2021

    Publisher: Elsevier BV

    DOI： 10.1016/j.proci.2020.08.055 　

    ISSN： 1540-7489

  23. Effects of OH concentration and temperature on NO emission characteristics of turbulent non-premixed CH4/NH3/air flames in a two-stage gas turbine like combustor at high pressure Peer-reviewed

    Kapuruge Don Kunkuma Amila Somarathne, Ekenechukwu C. Okafor, Daiki Sugawara, Akihiro Hayakawa, Hideaki Kobayashi

    Proceedings of the Combustion Institute　38　(4)　5163-5170　2021

    DOI： 10.1016/j.proci.2020.06.276 　

    ISSN： 1540-7489

    eISSN： 1873-2704

  24. Experimental and numerical study of product gas characteristics of ammonia/air premixed laminar flames stabilized in a stagnation flow Peer-reviewed

    Akihiro Hayakawa, Yuta Hirano, Ekenechukwu C. Okafor, Hirofumi Yamashita, Taku Kudo, Hideaki Kobayashi

    Proceedings of the Combustion Institute　38　(2)　2409-2417　2021

    DOI： 10.1016/j.proci.2020.07.030 　

    ISSN： 1540-7489

    eISSN： 1873-2704

  25. Influence of wall heat loss on the emission characteristics of premixed ammonia-air swirling flames interacting with the combustor wall Peer-reviewed

    Ekenechukwu C. Okafor, Masaaki Tsukamoto, Akihiro Hayakawa, K.D. Kunkuma A. Somarathne, Taku Kudo, Taku Tsujimura, Hideaki Kobayashi

    Proceedings of the Combustion Institute　38　(4)　5139-5146　2021

    DOI： 10.1016/j.proci.2020.06.142 　

    ISSN： 1540-7489

    eISSN： 1873-2704

  26. Laser Induced Thermal Grating Spectroscopy (LITGS) による温度定量計測の基礎と応用 Invited

    早川晃弘, 近藤広海

    日本燃焼学会誌　62　(202)　325-332　2020/11

  27. Combustion Characteristics of a Cavity Flameholder with a Burned-Gas Injector at the Cavity Bottom Wall in a Scramjet Model Combustor Peer-reviewed

    Tatsuya YAMAGUCHI, Tomohiro HIZAWA, Yasuto YUGAMI, Mariko HASEGAWA, Taku KUDO, Akihiro HAYAKAWA, Hideaki KOBAYASHI

    TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES　63　(4)　160-171　2020/07

    Publisher: Japan Society for Aeronautical and Space Sciences

    DOI： 10.2322/tjsass.63.160 　

    ISSN： 0549-3811

    eISSN： 2189-4205

  28. Turbulent burning velocity of ammonia/oxygen/nitrogen premixed flame in O2-enriched air condition Peer-reviewed

    Yu Xia, Genya Hashimoto, Khalid Hadi, Nozomu Hashimoto, Akihiro Hayakawa, Hideaki Kobayashi, Osamu Fujita

    Fuel　268　117383-117383　2020/05

    Publisher: Elsevier {BV}

    DOI： 10.1016/j.fuel.2020.117383 　

  29. Novel dilution sampling method for gas analysis with a low sampling rate Peer-reviewed

    Akihiro HAYAKAWA, Yuta HIRANO, Akinori ICHIKAWA, Keishi MATSUO, Taku KUDO, Hideaki KOBAYASHI

    Mechanical Engineering Journal　7　(2)　19-00193　2020/04

    Publisher: Japan Society of Mechanical Engineers

    DOI： 10.1299/mej.19-00193 　

    eISSN： 2187-9745

  30. Flow Field and Combustion Field Control using Pylons Installed Upstream of a Cavity in Supersonic Flow Peer-reviewed

    Tomohiro Hizawa, Tatsuya Yamaguchi, Ko Murata, Yasuto Yugami, Mariko Hasegawa, Taku Kudo, Akihiro Hayakawa, Hideaki Kobayashi

    Transactions of the Japan Society for Aeronautical and Space Sciences　63　50-61　2020/03

  31. Experimental Study of Turbulent Flame Propagation Limits of NH3/CH4/air Premixed Gas in A Constant Volume Combustion Chamber

    Hashimoto Genya, Hadi Khalid, Xia Yu, Hamid Aainaa, Hashimoto Nozomu, Hayakawa Akihiro, Kobayashi Hideaki, Fujita Osamu

    The Proceedings of the Thermal Engineering Conference　2020　80-80　2020

    Publisher: The Japan Society of Mechanical Engineers

    DOI： 10.1299/jsmeted.2020.0080 　

    More details Close

    <p>In this study, the flame propagation experiments of ammonia/methane/air were conducted using a fan-stirred constant volume vessel in order to clarify the effect of turbulence on the propagation limits of the ammonia/methane/air. Results show that the ammonia/methane/air mixture with a 0.9 equivalence ratio can propagate at the highest turbulence intensity and flames can propagate in larger turbulence Karlovitz number at smaller Markstein number. These tendencies are considered to be due to the diffusional-thermal instability of the flame surface.</p>

  32. Control of NOx and Other Emissions in Micro Gas Turbine Combustors Fuelled with Mixtures of methane and Ammonia Peer-reviewed

    E.C. Okafor, K.D.K.A. Somarathne, R. Ratthanan, A. Hayakawa, T. Kudo, O. Kurata, N. Iki, T. Tsujimura, H. Furutani, H. Kobayashi

    Combustion and Flame　211　406-416　2020/01

    DOI： 10.1016/j.combustflame.2019.10.012 　

    ISSN： 0010-2180

    eISSN： 1556-2921

  33. Experimental and numerical investigation of laminar burning velocities of artificial biogas under various pressure and CO<inf>2</inf> concentration

    Willyanto Anggono, Akihiro Hayakawa, Ekenechukwu C. Okafor, Gabriel Jeremy Gotama

    E3S Web of Conferences　130　2019/11/15

    DOI： 10.1051/e3sconf/201913001037 　

    ISSN： 2555-0403

    eISSN： 2267-1242

  34. アンモニア燃焼研究の意義とインパクト Peer-reviewed

    小林秀昭, 早川晃弘

    日本燃焼学会誌　61　(198)　277-282　2019/11

  35. Emission Characteristics of Turbulent Non-Premixed Ammonia/Air and methane/Air Swirl Flames Through a Rich-lean Combustor Under Various Wall Thermal Boundary Conditions at High Pressure Peer-reviewed

    K.D.K.A. Somarathne, E.C. Okafor, A. Hayakawa, T. Kudo, O. Kurata, N. Iki, H. Kobayashi

    Combustion and Flame　210　247-261　2019/07

    DOI： 10.1016/j.combustflame.2019.08.037 　

    ISSN： 0010-2180

    eISSN： 1556-2921

  36. OH Planar Laser-Induced Fluorescence Measurement for H2/O2 Jet Diffusion Flames in Rocket Combustion Condition up to 7.0MPa Peer-reviewed

    Y. Higuchi, K. Takeuchi, Y. Nunome, S. Tomioka, K. Sakaki T. Kudo, A. Hayakawa, H. Kobayashi

    Journal of Thermal Science and Technology　14　(2)　JTST0018-JTST0018　2019/07

    Publisher: The Japan Society of Mechanical Engineers and The Heat Transfer Society of Japan

    DOI： 10.1299/jtst.2019jtst0018 　

    More details Close

    <p>This study focuses on the application of OH planar laser-induced fluorescence (OH-PLIF) in high-pressure rocket combustion conditions, up to 7.0 MPa. The signal to noise ratio of PLIF degrades in high-pressure combustion owing to effects such as line broadening and interference from intense chemiluminescence. The OH(2,0) band excitation method was applied to obtain the OH(2,1) fluorescence emitted near 290 nm and filter out the intense OH(0,0) band chemiluminescence emitted near 308 nm. The gaseous H2/O2 (GH2/GO2) jet diffusion flame was formed using a recessed coaxial shear injector. The GH2/GO2 injection Reynolds number, Re (ReH2/ReO2 ≈ 2320/22800–4660/45600), was varied to examine the variation of the flame structure and reaction zone thickness under each pressure condition Pc, and Re injection condition. In addition, the variation of the experimentally derived full width at half maximum (FWHM) of the radial OH distribution, δOH, with the Damköehler number, Da, was compared with that of the simulated FWHM of the OH mole fraction, δOH-SIM. The OH distribution was clearly observed in the instantaneous PLIF image while eliminating the intense OH chemiluminescence even in the highest pressure condition of 7.0 MPa, which is a pressure higher than any of the previous OH-PLIF studies conducted on rocket combustion. The flame structure showed the typical characteristics of a turbulent jet diffusion flame and depended on Re rather than on the chamber pressure Pc. The variation of δOH with Da corresponded qualitatively with δOH-SIM and showed the characteristics of flame stretch in the vicinity of the injector.</p>

  37. アンモニア直接燃焼 Invited Peer-reviewed

    小林秀昭, 早川晃弘

    水素エネルギーシステム　44　(2)　105-113　2019/06

  38. Measurement and Modelling of the Laminar Burning Velocity of Methane-ammonia-air Flames at High Pressures using a Reduced Reaction Mechanisms Peer-reviewed

    E.C. Okafor, Y. Naito, S. Colson, A. Ichikawa, T. Kudo, A. Hayakawa, H. Kobayashi

    Combustion and Flame　204　162-175　2019/03/07

    ISSN： 0010-2180

  39. Extinction Limits of an Ammonia/air Flame Propagating in a Turbulent Field Peer-reviewed

    R. Ichimura, K. Hadi, N. Hashimoto, A. Hayakawa, H. Kobayashi, O. Fujita

    Fuel　246　178-186　2019/02/28

  40. Burning Velocity and Flame Structure of CH4/NH3/air Turbulent Premixed Flames at High Pressure Peer-reviewed

    A. Ichikawa, Y. Naito, A. Hayakawa, T. Kudo, H. Kobayashi

    International Journal of Hydrogen Energy　44　6991-6999　2019/02/16

  41. Investigation of effective fuel injection systems for scramjet model combustor with double pylon

    Yasuto Yugami, Tomohiro Hizawa, Tatsuya Yamaguchi, Mariko Hasegawa, Akihiro Hayakawa, Taku Kudo, Hideaki Kobayashi

    12th Asia-Pacific Conference on Combustion, ASPACC 2019　2019

    Publisher: Combustion Institute

  42. Performance improvement of a cavity flameholder by pylon installation in supersonic flow

    Mariko Hasegawa, Tomohiro Hizawa, Tatsuya Yamaguchi, Yasuto Yugami, Taku Kudo, Akihiro Hayakawa, Hideaki Kobayashi

    12th Asia-Pacific Conference on Combustion, ASPACC 2019　2019

    Publisher: Combustion Institute

  43. Emission Characteristics of Turbulent Non-premixed CH4/NH3/air Swirl Flames through a Rich-Lean Gas Turbine-like Combustor at High Pressure

    K. D.K.A. Somarathne, E. C. Okafor, A. Hayakawa, H. Kobayashi

    12th Asia-Pacific Conference on Combustion, ASPACC 2019　2019

  44. Product gas characteristics of strain stabilized ammonia/air premixed laminar flames

    Akihiro Hayakawa, Yuta Hirano, Ekenechukwu C. Okafor, Taku Kudo, Hideaki Kobayashi

    12th Asia-Pacific Conference on Combustion, ASPACC 2019　2019

  45. On the control of NOx emission from a micro gas turbine combustor fueled with mixtures of methane and ammonia

    Ekenechukwu C. Okafor, Rattanasupapornsak Ratthanan, K. A.D, Kunkuma Somarathne, Akihiro Hayakawa, Taku Kudo, Osamu Kurata, Norihiko Iki, Taku Tsujimura, Hideaki Kobayashi

    12th Asia-Pacific Conference on Combustion, ASPACC 2019　2019/01/01

  46. Science and Technology of Ammonia Combustion Peer-reviewed

    H. Kobayashi, A. Hayakawa, K.D.K.A. Somarathne, E.C. Okafor

    Proceedings of the Combustion Institute　37　(1)　109-133　2019/01

    DOI： 10.1016/j.proci.2018.09.029 　

    ISSN： 1540-7489

    eISSN： 1873-2704

  47. Development of a Wide Range-operatable, Rich-lean Low-NOx Combustor for NH3 Fuel Gas-turbine Power Generation Peer-reviewed

    O. Kurata, N. Iki, T. Inoue, T. Matsunuma, T. Tsujimura, H. Furutani, M. Kawano, K. Arai, E.C. Okafor, A. Hayakawa, H. Kobayashi

    Proceedings of the Combustion Institute　37　(4)　4587-4595　2019/01

    DOI： 10.1016/j.proci.2018.09.012 　

    ISSN： 1540-7489

    eISSN： 1873-2704

  48. Quantitative Measurement of Temperature in Oxygen Enriched CH4/O2/N2 Premixed Flames using Laser Induced Thermal Grating Spectroscopy (LITGS) up to 1.0 MPa Peer-reviewed

    A. Hayakawa, T. Yamagami, K. Takeuchi, Y. Higuchi, T. Kudo, S. Lowe, Y. Gao, S. Hochgreb, H. Kobayashi

    Proceedings of the Combustion Institute　37　1427-1434　2019/01

  49. Towards the Development of an Efficient Low-NOx Ammonia Combustor for a Micro Gas Turbine Peer-reviewed

    E.C. Okafor, K.D.K.A. Somarathne, A. Hayakawa, T. Kudo, O. Kurata, N. Iki, H. Kobayashi

    Proceedings of the Combustion Institute　37　(4)　4597-4606　2019/01

    DOI： 10.1016/j.proci.2018.07.083 　

    ISSN： 1540-7489

  50. Development and Verification of a Supersonic nozzle with a Rectangular Cross Section at a Mach Number of 2.8 for a Scramjet Model Combustor Peer-reviewed

    T. Yamaguchi, T. Hizawa, T. Ichikawa, T.Kudo, A. Hayakawa, H. Kobyashi

    Journal of Thermal Science and Technology,　13　(2)　2018/11/20

  51. Total Temperature Estimation of a Hydrogen/air Burned-gas Torch Igniter for a Scramjet Combustor Peer-reviewed

    T. Yamaguchi, T. Hizawa, T. Ichikawa, T.Kudo, A. Hayakawa, H. Kobyashi

    Journal of Thermal Science and Technology,　13　(2)　2018/10/10

  52. Modelling of Ammonia/air Non-premixed Turbulent Swirling Flames in a Gas Turbine-like Combustor at Various Pressures Peer-reviewed

    K.D.K.A. Somarathne, S. Colson, A. Hayakawa, H. Kobayashi

    Combustion Theory and Modelling　22　(5)　973-997　2018/06/26

  53. NOx Reduction in a Swirl Combustor Firing Ammonia for a Micro Gas Turbine Peer-reviewed

    Norihiko Iki, Osamu Kurata, Takayuki Matsunuma, Takahiro Inoue, Taku Tsujimura, Hirohide Furutani, Hideaki Kobayashi, Akihiro Hayakawa, Ekenechukwu Okafor

    ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition　8　2018

    DOI： 10.1115/GT2018-75993 　

  54. Development of a water-cooled multi-hole calibration burner for optical measurements of flames with high pressures and temperatures Peer-reviewed

    Kiyonori Takeuchi, Yoshio Nunome, Sadatake Tomioka, Takeo Tomita, Taku Kudo, Akihiro Hayakawa, Hideaki Kobayashi

    Journal of Thermal Science and Technology　13　(1)　2018

    Publisher: Japan Society of Mechanical Engineers

    DOI： 10.1299/jtst.2018jtst0001 　

    ISSN： 1880-5566

  55. Experimental and numerical study of the laminar burning velocity of CH4-NH3-air premixed flames Peer-reviewed

    Ekenechukwu C. Okafor, Yuji Naito, Sophie Colson, Akinori Ichikawa, Taku Kudo, Akihiro Hayakawa, Hideaki Kobayashi

    COMBUSTION AND FLAME　187　185-198　2018/01

    DOI： 10.1016/j.combustflame.2017.09.002 　

    ISSN： 0010-2180

    eISSN： 1556-2921

  56. Numerical Study of a Low Emission Gas Turbine Like Combustor for Turbulent Ammonia/Air Premixed Swirl Flames With a Secondary Air Injection at High Pressure Peer-reviewed

    K.D.K.A. Somarathne, S. Hatakeyama, A. Hayakawa, H.Kobayashi

    International Journal of Hydrogen Energy　42　(44)　27388-27399　2017/10

    ISSN： 0360-3199

  57. Experimental investigation of stabilization and emission characteristics of ammonia/air premixed flames in a swirl combustor Peer-reviewed

    Akihiro Hayakawa, Yoshiyuki Arakawa, Rentaro Mimoto, K. D. Kunkuma A. Somarathne, Taku Kudo, Hideaki Kobayashi

    INTERNATIONAL JOURNAL OF HYDROGEN ENERGY　42　(19)　14010-14018　2017/05

    DOI： 10.1016/j.ijhydene.2017.01.046 　

    ISSN： 0360-3199

    eISSN： 1879-3487

  58. Simultaneous, two-camera, 2D gas-phase temperature and velocity measurements by thermographic particle image velocimetry with ZnO tracers Peer-reviewed

    L. Fan, Y. Gao, A. Hayakawa, S. Hochgreb

    EXPERIMENTS IN FLUIDS　58　(4)　2017/04

    DOI： 10.1007/s00348-017-2313-2 　

    ISSN： 0723-4864

    eISSN： 1432-1114

  59. SUCCESS OF AMMONIA-FIRED, REGENERATOR-HEATED, DIFFUSION COMBUSTION GAS TURBINE POWER GENERATION AND PROSPECT OF LOW NOX COMBUSTION WITH HIGH COMBUSTION EFFICIENCY Peer-reviewed

    Osamu Kurata, Norihiko Iki, Takayuki Matsunuma, Takahiro Inoue, Taku Tsujimura, Hirohide Furutani, Akihiro Hayakawa, Hideaki Kobayashi

    PROCEEDINGS OF THE ASME POWER CONFERENCE JOINT WITH ICOPE-17, 2017, VOL 1　2017

  60. Combustion emissions from nh3 fuel gas turbine power generation demonstrated

    Osamu Kurata, Norihiko Iki, Takahiro Inoue, Takayuki Matsunuma, Taku Tsujimura, Hirohide Furutani, Hideaki Kobayashi, Akihiro Hayakawa

    NH3 Energy+- Enabling Optimized, Sustainable Energy and Agriculture 2017 - Topical Conference at the 2017 AIChE Annual Meeting　2017-October　162-170　2017/01/01

  61. Performances and emission characteristics of NH3-air and NH3-CH4-air combustion gas-turbine power generations Peer-reviewed

    Osamu Kurata, Norihiko Iki, Takayuki Matsunuma, Takahiro Inoue, Taku Tsujimura, Hirohide Furutani, Hideaki Kobayashi, Akihiro Hayakawa

    PROCEEDINGS OF THE COMBUSTION INSTITUTE　36　(3)　3351-3359　2017

    DOI： 10.1016/j.proci.2016.07.088 　

    ISSN： 1540-7489

    eISSN： 1873-2704

  62. Application of OH(2,0) Band Excitation Planar Laser-Induced Fluorescence to High-Pressure H-2/O-2 Jet Flames for Rocket Combustion Peer-reviewed

    Kiyonori Takeuchi, Yoshio Nunome, Sadatake Tomioka, Takeo Tomita, Taku Kudo, Akihiro Hayakawa, Hideaki Kobayashi

    TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES　60　(2)　116-123　2017

    ISSN： 0549-3811

  63. OPERATION AND FLAME OBSERVATION OF MICRO GAS TURBINE FIRING AMMONIA Peer-reviewed

    Norihiko Iki, Osamu Kurata, Takayuki Matsunuma, Takahiro Inoue, Taku Tsujimura, Hirohide Furutani, Hideaki Kobayashi, Akihiro Hayakawa

    PROCEEDINGS OF THE ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2017, VOL 8　2017

    DOI： 10.1115/GT2016-56954 　

  64. Numerical Investigation on the Combustion Characteristics of Turbulent Premixed Ammonia/air Flames Stabilized by a Swirl Burner Peer-reviewed

    K.D.K.A. Somarathne, A. Hayakawa, H. Kobayashi

    Journal of Fluid Science and Technology　11　(4)　2016/12/28

    DOI： 10.1299/jfst.2016jfst0026 　

    ISSN： 1880-5558

  65. Gas Turbine Power Generation System firing Ammonia-Methane Mixture Peer-reviewed

    N. Iki, O. Kurata, T. Matsunuma, T. Inoue, T. Tsujimura, H. Furutani, H. Kobayashi, A. Hayakawa

    Proceedings of the Asian Congress on Gas Turbines　1-6　2016/11/14

  66. Effect of Cavity with a Pylon on the Flame in Supersonic Flow

    K. Murata, T. Yamaguchi, T. Kudo, A. Hayakawa, H. Kobayashi

    Proceedings of the Thirteenth International Conference on Flow Dynamics　730-731　2016/10/11

  67. Effects of NH3 Addition on the Laminar Burning Velocity and Markstein Length of CH4-Air Premixed Flames

    E. C. Okafor, Y. Naito, A. Ichikawa, T. Kudo, A. Hayakawa, H. Kobayashi

    Proceedings of the Thirteenth International Conference on Flow Dynamics,　210-211　2016/10/11

  68. Flame Stabilization Limits and Emission Characteristics of an Ammonia Micro Gas Turbine Combustor

    K. Sakai, E.C. Okafor, A. Hayakawa, T. Kudo, H. Kobayashi, N. Iki, O. Kurata

    Proceedings of the Thirteenth International Conference on Flow Dynamics　751-752　2016/10/11

  69. Quantitative Temperature Measurement of High Pressure Flame by Using laser Induced Thermal Grating Spectroscopy (LITGS)

    A. Hayakawa, T. Yamagami, S. Lowe, T. Kudo, Y. Gao, S. Hochgreb, H. Kobayashi

    Proceedings of the Sixteenth International Symposium on Advanced Fluid Information　142-143　2016/10/11

  70. Laser Induced Thermal Grating Spectroscopy (LITGS) and Thermographic PIV for Quantitative Measurement

    A. Hayakawa, S. Lowe, Y. Gao, L. Fan, S. Hochgreb

    Proceedings of the Sixteenth International Symposium on Advanced Fluid Information (AFI-2016)　182-183　2016/10

  71. Ammonia-fired gas turbine power generation system

    O. Kurata, N. Iki, T. Matsunuma, T. Inoue, T. Tsujimura, H. Furutani, H. Kobayashi, A. Hayakawa

    Proceedings of the 21st World Hydrogen Energy Conference　147-148　2016/06/15

  72. Stabilization and Emission Characteristics of Ammonia/air Premixed Flames in Swirling Flows

    A. Hayakawa, Y. Arakawa, R. Mimoto, K.D.K.A. Somarathne, T. Kudo, H. Kobayashi

    Proceedings of the 21st World Hydrogen Energy Conference　626-627　2016/06/15

  73. 超音速流における衝撃波干渉するキャビティー保炎器下流の燃焼メカニズム Peer-reviewed

    小林秀昭, 石本裕美, 工藤琢, 早川晃弘

    日本航空宇宙学会論文集　64　(2)　97-103　2016/04/05

    Publisher: THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

    DOI： 10.2322/jjsass.64.97 　

    ISSN： 1344-6460

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    The objective of this study is to explore the effects of incident shock waves on combustion downstream of a cavity flameholder. The images of flame chemiluminescence showed that the flame looks extinguished downstream of an incident shock wave, as well as OH-PLIF measurements indicated higher OH concentration upstream of the incident shock wave, while lower OH concentration downstream of the incident shock wave. The results of two-dimensional numerical simulations for reacting flows showed that the incident shock wave generates a strong recirculation zone and reverse flows, and the main flow curved around the zone, corresponding well to the flame structure seen by experiments. In addition, it was found that about 90% of the injected H2 was converted to H2O at the rear edge of the calculated wall domain when an incident shock wave was introduced, which means that cavity-stabilized flames is not extinguished by the incident shock wave but burnt out there, thus the fuel was almost fully consumed. That is to say, the incident shock wave enhances chemical reactions because the generated recirculation zone and low speed region increases residence time and increased turbulent kinetic energy enhances the mixing.

  74. A Study of Cavity Combustion for Pre-burnt Injection Gas From a Single Hole in Supersonic Air Stream Peer-reviewed

    T. Yamaguchi, K. Murata, T. Kudo, A. Hayakawa, H. Kobayashi

    Proceedings of the First Pacific Rim Thermal Engineering Conference　PRTEC-14721　2016/03

  75. Flame Stability Limits and Emission Characteristics of an Ammonia Micro Gas Turbine Burner

    Okafor Ekenechukwu C., Sakai Kazuma, Hayakawa Akihiro, Kudo Taku, Kobayashi Hideaki, Iki Norihiko, Kurata Osamu

    The Proceedings of the Thermal Engineering Conference　2016　E214　2016

    Publisher: The Japan Society of Mechanical Engineers

    DOI： 10.1299/jsmeted.2016.E214 　

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    <p>The stability limits and emission characteristics of ammonia-air diffusion flames stabilized by swirl were investigated using a 50 kW micro gas turbine burner. Two liners were used, a cylindrical glass liner and a tapered gas turbine (GT) model liner. The flames were stabilized at equivalence ratios of 0.7 to 1.4 at inlet gas temperature of 298 K. The GT model liner resulted to a slightly wider stability range and lower unburnt ammonia emission. For both liners, ammonia emission increased while NOx emission decreased with equivalence ratio. The sum of NOx and ammonia emissions were found to be minimal at stoichiometric condition.</p>

  76. MICRO GAS TURBINE FIRING AMMONIA Peer-reviewed

    Norihiko Iki, Osamu Kurata, Takayuki Matsunuma, Takahiro Inoue, Taku Tsujimura, Hirohide Furutani, Hideaki Kobayashi, Akihiro Hayakawa, Yoshiyuki Arakawa, Akinori Ichikawa

    PROCEEDINGS OF THE ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2016, VOL 8　2016

  77. Effects of Incident Shockwave on Flame-holding Downstream of Ramp Injector in Supersonic Flow Peer-reviewed

    Yoshitaka Iwamura, Tatsuya Yamaguchi, Akihiro Hayakawa, Taku Kudo, Hideaki Kobayashi

    TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES　59　(2)　64-70　2016

    DOI： 10.2322/tjsass.59.64 　

    ISSN： 0549-3811

  78. The Influence of CO2 in Biogas Flammability Limit and Laminar Burning Velocity in Spark Ignited Premix Combustion at Various Pressures Peer-reviewed

    W. Anggono, I. N. G. Wardana, M. Lawes, K. J. Hughes, S. Wahyudi, N. Hamidi, A. Hayakawa

    PROCEEDINGS OF THE 4TH INTERNATIONAL CONFERENCE AND EXHIBITION OF SUSTAINABLE ENERGY AND ADVANCED MATERIALS 2015 (ICE-SEAM 2015)　1717　(03001)　2016

    DOI： 10.1063/1.4943425 　

    ISSN： 0094-243X

  79. Extinction characteristics of ammonia/air counterflow premixed flames at various pressures Peer-reviewed

    Sophie Colson, Akihiro Hayakawa, Taku Kudo, Hideaki Kobayashi

    JOURNAL OF THERMAL SCIENCE AND TECHNOLOGY　11　(3)　2016

    DOI： 10.1299/jtst.2016jtst0048 　

    ISSN： 1880-5566

  80. Laminar burning velocity and Markstein length of ammonia/air premixed flames at various pressures Peer-reviewed

    Akihiro Hayakawa, Takashi Goto, Rentaro Mimoto, Yoshiyuki Arakawa, Taku Kudo, Hideaki Kobayashi

    FUEL　159　98-106　2015/11

    DOI： 10.1016/j.fuel.2015.06.070 　

    ISSN： 0016-2361

    eISSN： 1873-7153

  81. Effects of Cross-flow on Liquid Sheet Break-up and Droplet Dimeters for Two-dimensional Air-blast Atomizer in High Pressure Environment

    K. Kato, S. Suzuki, T. Kudo, S. Kato, M. Uchida, A. Hayakawa, H. Kobayashi

    Proceedings of the Twelfth International Conference on Flow Dynamics (12th ICFD2015)　266-267　2015/10

  82. Flame Characteristics of Ammonia and Methane Flames in a Swirl Combustor

    Y. Arakawa, A. Hayakawa, K.D.K.A. Somarathne, T. Kudo, H. Kobayashi

    Proceedings of the Twelfth International Conference on Flow Dynamics (12th ICFD2015)　708-709　2015/10

  83. Numerical Analysis of Combustion Enhancement by Ozone Addition and Shock Wave Interaction in Supersonic Flow

    K. Murata, J. Kurasawa, T. Kudo, A. Hayakawa, H. Kobayashi

    Proceedings of the Twelfth International Conference on Flow Dynamics (12th ICFD2015)　722-723　2015/10

  84. Numerical Investigation on the Combustion Characteristics of Turbulent Premixed Swirl Flames for Ammonia/air Mixture

    K.D.K.A. Somarathne, A. Hayakawa, H. Kobayashi

    Proceedings of the Twelfth International Conference on Flow Dynamics (12th ICFD2015)　220-221　2015/10

  85. Laminar burning velocity and Markstein length of ammonia/hydrogen/air premixed flames at elevated pressures Peer-reviewed

    Akinori Ichikawa, Akihiro Hayakawa, Yuichi Kitagawa, K. D. Kunkuma Amila Somarathne, Taku Kudo, Hideaki Kobayashi

    INTERNATIONAL JOURNAL OF HYDROGEN ENERGY　40　(30)　9570-9578　2015/08

    DOI： 10.1016/j.ijhydene.2015.04.024 　

    ISSN： 0360-3199

    eISSN： 1879-3487

  86. Flame Characteristics of Ammonia/hydrogen/air Premixed Flames at Elevated Pressures Peer-reviewed

    A. Ichikawa, Y. Kitagawa, A. Hayakawa, T. Kudo, H. Kobayashi

    Proceedings of the 10th Asia-Pacific Conference on Combustion　2015/07

  87. NO Formation/reduction Mechanisms of Ammonia/air Premixed Flames at Various Equivalence Ratios and Pressures Peer-reviewed

    A. Hayakawa, T. Goto, R.Mimoto, T. Kudo, H. Kobayashi

    Mechanical Engineering Journal　2　(1)　2015/02/15

    Publisher: The Japan Society of Mechanical Engineers

    DOI： 10.1299/mej.14-00402 　

    ISSN： 2187-9745

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    Ammonia is a carbon-free fuel and its application to internal combustion engines is expected. However, few studies on ammonia flames, especially at high pressures, have been carried out because ammonia has not been considered to be a fuel owing to its lower combustion intensity. Most NOx, which is formed by ammonia combustion, is considered to be the fuel NOx. The objectives of this study were to investigate the fundamental characteristics of NOx experimentally, such as NO emission and chemiluminescence of ammonia/air flames not only at the atmospheric pressure but also under high pressures and to explore NO formation/reduction mechanisms using numerical simulation. Experiments were carried out using a nozzle-type burner. NH2 ammonia α band spectra were observed, and it was clarified that the color of ammonia flame is mainly determined by the NH2 ammonia α band and H2O spectra. Burned gas was sampled from ammonia flame stabilized at the burner. The mole fraction of NO decreased with the increase in equivalence ratio at atmospheric pressure. Reaction flow analysis was performed, and it was clarified that the decrease in the mole fraction of NO for rich mixtures was caused by NHi (i = 2, 1, 0). High pressure experiments were performed using a high pressure combustion facility for stoichiometric ammonia flame. Consequently, the decrease in the mole fraction of NO was experimentally observed and its tendency was found to qualitatively agree with the results of the numerical simulation. It was clarified that the third body reaction of OH + H + M ⇔ H2O + M plays an important role in the reduction of the mole fraction of NO at the high pressure.

  88. Application of OH-PLIF measurements using OH(2,0) band excitations to high pressure H2/O2 jet diffusion flames

    Kiyonori Takeuchi, Yoshio Nunome, Takeo Tomita, Taku Kudo, Akihiro Hayakawa, Hideaki Kobayashi

    ASPACC 2015 - 10th Asia-Pacific Conference on Combustion　2015

    Publisher: Combustion Institute

  89. Combustion Enhancement by Ozone Addition in Supersonic Flow

    J. Kurasawa, K. Murata, T. Kudo, A. Hayakawa, H. Kobayashi

    Proceedings of the Eleventh International Conference on Flow Dynamics (11th ICFD 2014)　522-523　2014/10

  90. Effects of Intermediate Species on Flame Instability in Turbulent Premixed Flames of Propanol Isomers at High Pressure

    S. Nakajima, T. Uchida, S. Soyoshi, T. Kudo, A. Hayakawa, S. Kadowaki, H. Kobayashi

    Proceedings of the Eleventh International Conference on Flow Dynamics (11th ICFD 2014)　500-501　2014/10

  91. Effects of Liquid Properties on Airblast Atomization in a High Pressure Environment

    S. Suzuki, K. Kato, T. Kudo, S. Kato, M. Ito, M. Uchida, A. Hayakawa, H. Kobayashi

    Proceedings of the Eleventh International Conference on Flow Dynamics (11th ICFD 2014)　448-449　2014/10

  92. Experimental and Numerical Investigations of Laminar Burning Velocity of Ammonia/air Premixed Flames

    A. Hayakawa, T. Goto, R. Mimoto, T.Kudo, H. Kobayashi

    Proceedings of the Eleventh International Conference on Flow Dynamics (11th ICFD 2014　226-227　2014/10

  93. Interaction between Incident Shock Wave and Pre-combustion Gas Injection from a Ramp Injector in Supersonic Flow

    T. Yamaguchi, Y. Iwamura, T. Kudo, A. Hayakawa, H. Kobayashi

    Proceedings of the Eleventh International Conference on Flow Dynamics (11th ICFD 2014)　530-531　2014/10

  94. OH-PLIF Measurements of GH2/GO2 Diffusion Flames Using Higher Electron Excitation Bands

    K. Takeuchi, Y. Nunome, T. Tomita, T. Kudo, A. Hayakawa, H. Kobayashi

    Proceedings of the Eleventh International Conference on Flow Dynamics (11th ICFD 2014)　502-503　2014/10

  95. Effects of Ambient Pressure and Liquid Properties on Atomization Characteristics of an Airblast Atomizer Peer-reviewed

    K. Kato, S. Suzuki, T. Kudo, S. Kato, M. Itoh, M. Uchida, A. Hayakawa, H. Kobayashi

    Book of Abstracts　157-158　2014/09

  96. 高圧環境におけるプレフィルミング型気流噴射弁の噴霧特性および噴霧形成過程 Peer-reviewed

    加藤昂大, 鈴木聡一郎, 工藤琢, 加藤壮一郎, 伊藤光紀, 早川晃弘, 小林秀昭

    学術刊行物 微粒化　23　(79)　37-44　2014/07

  97. Effects of hydrogen concentration on premixed laminar flames of hydrogen-methane-air Peer-reviewed

    Ekenechukwu C. Okafor, Akihiro Hayakawa, Yukihide Nagano, Toshiaki Kitagawa

    INTERNATIONAL JOURNAL OF HYDROGEN ENERGY　39　(5)　2409-2417　2014/02

    DOI： 10.1016/j.ijhydene.2013.11.128 　

    ISSN： 0360-3199

    eISSN： 1879-3487

  98. Characteristics of Ammonia/air Laminar Premixed Flames and NO Formation/Reduction Mechanism

    H. Kobayashi, A. Hayakawa, T. Goto, R. Mimoto, T. kudo

    Proceedings of the Taiwan-Japan Fuel Cell-Energy Carrier Workshop　31-32　2013/12

  99. Effects of Ambient Pressure on Liquid Sheet Breakup of Airblast Atomizer

    K. Kato, S. Suzuki, T. Kudo, S. Kato, M. Itoh, A. Hayakawa, H. Kobayashi

    Proceedings of the Tenth International Conference on Flow Dynamics　708-709　2013/11

  100. Interaction between Incident Shock Wave and Combustion Downstream of Ramp Injector in Supersonic Flow

    Y. Iwamura, T. Yamaguchi, T. kudo, A. Hayakawa, H. Kobayashi

    Proceedings of the Tenth International Conference on Flow Dynamics　626-627　2013/11

  101. 球状伝播予混合乱流火炎の燃焼速度および火炎面形状の有効乱れ強さによる変化 Peer-reviewed

    早川晃弘, 三木由希人, 久保俊彦, 永野幸秀, 北川敏明

    日本燃焼学会誌　55　(172)　202-209　2013/05

    Publisher:

    DOI： 10.20619/jcombsj.55.172_202 　

    ISSN： 1347-1864

  102. Experimental and numerical studies on burning velocities and Markstein numbers on lean laminar H2/CH4/air flames Peer-reviewed

    Ekenechukwu C. Okafor, Masashi Toyoda, Akihiro Hayakawa, Yukihide Nagano, Toshiaki Kitagawa

    Proceedings of The 9th Asia-Pacific Conference on Combustion　2013/05

  103. Biogas Laminar Burning Velocity and Flammability Characteristics in Spark Ignited Premix Combustion Peer-reviewed

    Willyanto Anggono, I. N. G. Wardana, M. Lawes, K. J. Hughes, Slamet Wahyudi, Nurkholis Hamidi, Akihiro Hayakawa

    2013 INTERNATIONAL CONFERENCE ON SCIENCE & ENGINEERING IN MATHEMATICS, CHEMISTRY AND PHYSICS (SCIETECH 2013)　423　2013

    DOI： 10.1088/1742-6596/423/1/012015 　

    ISSN： 1742-6588

  104. Experimental and Numerical Simulation on Biogas Flame Propagation Characteristic in Spark Ignition Premixed Combustion

    Willyanto Anggono, ING Wardana, M. Pourkashanian, K.J. Hughes, M. Lawes, Slamet Wahyudi, Nurkholis Hamidi, Akihiro Hayakawa

    Proceedings of The 3rd International Conference on Engineering & ICT (ICEI2012)　2　290-294　2012/04

  105. Effects of Hydrogen Concentration on Hydrogen-Methane-Air Lean Laminar Flames

    Ekenechukwu Chijioke Okafor, Akihiro Hayakawa, Yukihide Nagano, Toshiaki Kitagawa

    Proceedings of The eighth KSME-JSME Thermal and Fluids Engineering Conference　2012/03

  106. Flame Front Shapes of Spherically Propagating Turbulent Premixed Flames at Various Pressures

    Akihiro Hayakawa, Yukito Miki, Toshihiko Kubo, Yukihide Nagano, Toshiaki Kitagawa

    Proceedings of The eighth KSME-JSME Thermal and Fluids Engineering Conference　2012/03

  107. 5-1-2 Combustion Properties of Coal Gasification Gas under High CO_2 Atmosphere

    NAGANO Yukihide, HAYAKAWA Akihiro, TOMARI Keiichro, TSURUDOME Hiroyuki, KITAGAWA Toshiaki

    Proceedings of the Annual Conference of The Japan Institute of Energy　21　262-263　2012

    Publisher: The Japan Institute of Energy

    DOI： 10.20550/jietaikaiyoushi.21.0_262 　

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    Combustion properties of coal gasification gas with CO_2 dilution were investigated for an IGCC power generation system with CO_2 capture. In this system, the gasification gas which consists of H_2 and CO, is bumed under high CO_2 concentration atmosphere. In order to clarify the effects of CO_2 dilution on its combustion, the laminar and turbulent burning velocities were measured for stoichiometric CO_2 diluted H_2/CO flame under the condition of constant flame temperatures of 1300 and 1700 degrees Celsius.

  108. Analysis of Turbulent Burning Velocity of Spherically Propagating Premixed Flame with Effective Turbulence Intensity Peer-reviewed

    Akihiro Hayakawa, Yukito Miki, Yukihide Nagano, Toshiaki Kitagawa

    JOURNAL OF THERMAL SCIENCE AND TECHNOLOGY　7　(4)　507-521　2012

    DOI： 10.1299/jtst.7.507 　

    ISSN： 1880-5566

  109. STUDY OF THERMO-DIFFUSIVE EFFECTS ON ISO-OCTANE/AIR FLAMES AT FIXED TURBULENCE KARLOVITZ NUMBER Peer-reviewed

    Akihiro Hayakawa, Tomohiro Takeo, Yukito Miki, Yukihide Nagano, Toshiaki Kitagawa

    PROCEEDINGS OF THE ASME/JSME 8TH THERMAL ENGINEERING JOINT CONFERENCE 2011, VOL 2　691-699　2011

  110. Combustion properties of hydrogen/air mixture with and without dilution Peer-reviewed

    Yukihide Nagano, Tomohiro Takeo, Keiichiro Tomari, Akihiro Hayakawa, Shoichi Kobayashi, Toshiaki Kitagawa

    SAE Technical Papers　2178-2185　2011

    DOI： 10.4271/2011-01-1999 　

  111. Effects of CO2 and N2 dilutions on laminar and turbulent flame propagation Peer-reviewed

    Akihiro Hayakawa, Yukito Miki, Shoichi Kobayashi, Yukihide Nagano, Toshiaki Kitagawa

    SAE Technical Papers　1718-1727　2011

    DOI： 10.4271/2011-01-1878 　

  112. 乱流Karlovitz数を揃えたイソオクタン／空気／不活性ガス予混合火炎に及ぼす熱－拡散効果の影響 Peer-reviewed

    早川晃弘, 竹尾友宏, 山下晋平, 小林正一, 北川敏明

    自動車技術会論文集　41　(2)　307-312　2010/03

    Publisher:

    DOI： 10.11351/jsaeronbun.41.307 　

    ISSN： 0287-8321

  113. G0700-2-4 Influence of Effective Turbulence Intensity on Burning Velocity of Spherically Propagating Premixed Turbulent Flame

    HAYAKAWA Akihiro, NAGANO Yukihide, KITAGAWA Toshiaki

    The proceedings of the JSME annual meeting　2010　87-88　2010

    Publisher: The Japan Society of Mechanical Engineers

    DOI： 10.1299/jsmemecjo.2010.3.0_87 　

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    Turbulent burning velocity of spherically propagating flame kept increasing with flame propagation. The turbulence which effectively wrinkles the flame front may be increasing with flame progress. Such turbulence intensity is called effective turbulence intensity and it is estimated from energy spectrum of turbulence. The relationship between burning velocity of spherically propagating turbulent flame and effective turbulence intensity was estimated. As a result, it is found that turbulent burning velocity is well correlated with turbulence Reynolds number based on Taylor micro scale and effective turbulence intensity regardless of turbulence intensity.

  114. イソオクタン予混合伝播火炎への混合気希釈の影響 ―二酸化炭素希釈と窒素希釈の比較― Peer-reviewed

    早川晃弘, 丸山晃助, 黒川陽平, 小林正一, 北川敏明

    自動車技術会論文集　41　(1)　61-66　2010/01

    Publisher: Society of Automotive Engineers of Japan

    DOI： 10.11351/jsaeronbun.41.61 　

    ISSN： 0287-8321

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    Exhaust Gas Recirculation (EGR) is one of the techniques for reducing NOx emissions. EGR gas consists mainly of N2, H2O and CO2. Properties of flame diluted with EGR gas might be influenced by these components. The effects of dilution with N2 on outwardly propagating laminar and turbulent flames were studied for stoichiometric iso-octane/air mixtures at the initial pressures from 0.10 to 0.50 MPa. The dilution rate, defined as the molar fraction of dilution gas in the air and dilution gas, was varied up to 0.10. The properties of diluted flames were discussed comparing N2 and CO2 dilution.

  115. Effects of pressure on laminar and turbulent burning velocities of ethanol premixed flames Peer-reviewed

    Kazutaka Ohara, Masayoshi Tsukikawa, Yousuke Araki, Akihiro Hayakawa, Shoichi Kobayashi, Yukihide Nagano, Toshiaki Kitagawa

    Nihon Enerugi Gakkaishi/Journal of the Japan Institute of Energy　89　(11)　1088-1094　2010

    DOI： 10.3775/jie.89.1088 　

    ISSN： 0916-8753

  116. イソオクタン層流および乱流予混合火炎に及ぼす二酸化炭素希釈の影響 －化学量論混合気の場合－ Peer-reviewed

    早川晃弘, 丸山晃助, 小林正一, 北川敏明

    自動車技術会論文集　40　(5)　1209-1215　2009/09

    Publisher: Society of Automotive Engineers of Japan

    DOI： 10.11351/jsaeronbun.40.1209 　

    ISSN： 0287-8321

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    The effects of mixture dilution with CO2 on outwardly propagating laminar and turbulent flames were studied for stoichiometric iso-octane / air mixtures at the initial pressures from 0.10 to 0.50MPa. The CO2 dilution rate, defined as the molar fraction of CO2 in the air and CO2, was varied up to 0.10. The unstretched laminar burning velocity decreased with increasing the dilution rate. The Markstein number decreased for increasing CO2 dilution rate. The ratios of turbulent burning velocity to unstretched laminar one increased with increasing CO2 dilution rate.

  117. メタン予混合火炎における火炎核の消炎とその発生要因 Peer-reviewed

    早川晃弘, 小林正一, 北川敏明

    自動車技術会論文集　40　(3)　811-816　2009/05

    Publisher: Society of Automotive Engineers of Japan

    DOI： 10.11351/jsaeronbun.40.811 　

    ISSN： 0287-8321

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    Quench of turbulent flame kernel and its incidence factors were studied for methane-air flames. Quench of turbulent flame kernel occurred at large turbulence Karlovitz numbers both for lean and rich flames. Lean flames quenched at higher turbulence Karlovitz numbers compared to rich flames because the Markstein number of lean flames were smaller than those of rich flames. Quench of rich flames may be due to the thermo-diffusive effects induced by the flame stretch. On the other hand, quench of lean flames may be due to the incomplete reaction because of their small burning velocities.

  118. 5-2-4 Effects of Pressure on Laminar and Turbulent Combustion Properties of Ethanol Premixed Flames

    OHARA Kazutaka, TSUKIKAWA Masayoshi, ARAKI Yousuke, HAYAKAWA Akihiro, KOBAYASHI Shoichi, KITAGAWA Toshiaki

    Proceedings of the Annual Conference of The Japan Institute of Energy　18　328-329　2009

    Publisher: The Japan Institute of Energy

    DOI： 10.20550/jietaikaiyoushi.18.0_328 　

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    The ratio of the turbulent burning velocity to the unstretched laminar burning velocity, u_l increased with increasing the ratio of turbulence intensity to u_l and turbulence Karlovitz number. This burning velocity ratio was large for rich flames. Thermo-diffusive effects might be more influential to rich ethanol flames because of the small Lewis number. This burning velocity ratio was also found to increase with increasing initial pressure.

  119. イソオクタン予混合火炎の層流および乱流燃焼速度に及ぼす圧力の影響 Peer-reviewed

    北川敏明, 丸山晃助, 中原崇志, 角邦洋, 早川晃弘

    自動車技術会論文集　40　(1)　81-86　2009/01

    Publisher: Society of Automotive Engineers of Japan

    DOI： 10.11351/jsaeronbun.40.81 　

    ISSN： 0287-8321

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    The effects of pressure on outwardly propagating laminar and turbulent flames were studied for iso-octane / air mixtures at the equivalence ratios from 0.8 to 1.4 and the initial pressures from 0.10 to 0.50MPa. Turbulence intensity was set to 0.80 and 1.59m/s. The Markstein number decreased for increasing pressures and for large equivalence ratios. The ratios of turbulent to unstretched laminar burning velocities at a constant Peclet number increased with increasing turbulence Karlovitz number and decreasing Markstein number at a constant pressure. However, the burning velocity ratios did not increase with increasing pressure although the Markstein number reduced with pressure.

  120. PROPERTIES OF ETHANOL LAMINAR AND TURBULENT PREMIXED FLAMES Peer-reviewed

    Kazutaka Ohara, Masayoshi Tsukikawa, Yousuke Araki, Akihiro Hayakawa, Shoichi Kobayashi, Toshiaki Kitagawa

    PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON POWER ENGINEERING 2009 (ICOPE-09), VOL 1　87-91　2009

  121. Turbulent burning velocity of hydrogen-air premixed propagating flames at elevated pressures Peer-reviewed

    Toshiaki Kitagawa, Takashi Nakahara, Kosuke Maruyama, Kunihiro Kado, Akihiro Hayakawa, Shoichi Kobayashi

    INTERNATIONAL JOURNAL OF HYDROGEN ENERGY　33　(20)　5842-5849　2008/10

    DOI： 10.1016/j.ijhydene.2008.06.013 　

    ISSN： 0360-3199

    eISSN： 1879-3487

  122. 2213 Effects of CO_2 Dilution on Laminar and Turbulent Burning Velocities of Iso-octane Premixed Propagating Flames

    KITAGAWA Toshiaki, MARUYAMA Kosuke, KADO Kunihiro, HAYAKAWA Akihiro

    The proceedings of the JSME annual meeting　2008　53-54　2008

    Publisher: The Japan Society of Mechanical Engineers

    DOI： 10.1299/jsmemecjo.2008.7.0_53 　

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    The effects of dilution of iso-octane/air mixtures with CO_2 on outwardly propagating laminar and turbulent flames were studied at the equivalence ratio of 1.0, the initial pressures from 0.10 to 0.50MPa and the dilution rate from 0 to 0.10. Turbulence intensity was set to 0.80 and 1.59m/s. The unstretched laminar burning velocity and the Markstein number decreased as the dilution rate increased. The ratios of turbulent to unstretched laminar burning velocities at a constant Peclet number increased with increasing turbulence Karlovitz number and decreasing Markstein number.

  123. 断熱燃焼温度を揃えた水素・メタン・プロパン予混合火炎に対する火炎伸張の影響 Peer-reviewed

    早川晃弘, 橋本淳

    津山工業高等専門学校紀要　48　29-36　2007/05

    Publisher: Tsuyama National College of Technology

    ISSN： 0287-7066

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    Recently, a development of the combustor having higher efficiency and being more clean has been required from the viewpoint of environmental problems. In a development process of such a combustor, computer simulation is an effective method for cost reduction. Large Eddy Simulation (LES) is one of the simulation technique of Fluid Dynamics. In recent years, it is attracting a lot of attention in the reason which can reproduce unsteady phenomena. When LES is applied to the flow field with combustion phenomena, it is necessary to give an appropriate combustion model. The flamelet existing in a flow field is affected by hydrodynamic strain. Burning velocity of such stretched flame changes from the value of laminar burning velocity by molecular and thermal diffusion effects. However, the combustion model which can evaluate such an effect adequately is not suggested till now. In this study, a response of burning velocity concerning flame stretch is examined by chemical kinetics computations. Especially, from a point of view of engineering, investigations are performed for premixed flames of hydrogen, methane and propane having the same adiabatic flame temperature. As a result, it is clarified that sensitivities to flame stretch of burning velocity can be explained approximately with mixture properties and ratio of those. Furthermore, in some mixture conditions, it becomes clear that the critical Lewis number play an important role in estimation of response.

Show all ︎Show first 5

Misc. 36

  1. Trial of Liquid Ammonia Spray Combustion for Gas Turbines

    倉田修, OKAFOR Ekenechukwu Chijioke, 山下裕史, 山下裕史, 壹岐典彦, 辻村拓, 内田正宏, 伊藤慎太朗, 須田俊之, 早川晃弘, 小林秀昭

    燃焼シンポジウム講演論文集(CD-ROM)　58th　2020

  2. Emission Characteristics of Liquid Ammonia and Gaseous Ammonia Flames Co-fired with Gaseous Hydrogen in a Gas Turbine-like Combustor at Moderately High Pressure

    SOMARATHNE Kapuruge Don Kunkuma Amila, YAMASHITA Hirofumi, COLSON Sophie, HAYAKAWA Akihiro, KUDO Taku, KOBAYASHI Hideaki

    Proceedings. International Conference on Flow Dynamics (CD-ROM)　19th　2022

  3. Study on the role of excess enthalpy in the stabilization of ammonia/air premixed flames in a swirling flow.

    COLSON Sophie, SOMARATHNE Kapuruge Don Kunkuma Amila, SUGAWARA Daiki, HAYAKAWA Akihiro, KOBAYASHI Hideaki

    燃焼シンポジウム講演論文集(CD-ROM)　59th　2021

  4. Numerical Study on Effects of Ammonia Fuel Fraction in Liquid Ammonia/Hydrogen/air Co-combustion at High Pressure

    SOMARATHNE Kapuruge Don Kunkuma Amila, COLSON Sophie, HAYAKAWA Akihiro, KOBAYASHI Hideaki

    燃焼シンポジウム講演論文集(CD-ROM)　59th　2021

  5. Liquid Ammonia Spray Characteristics Using a Hollow Cone Nozzle at Various Ambient Pressures

    SOMARATHNE Kapuruge Don Kunkuma Amila, YAMASHITA Hirofumi, YAMASHITA Hirofumi, COLSON Sophie, HAYAKAWA Akihiro, KOBAYASHI Hideaki.

    Proceedings. International Conference on Flow Dynamics (CD-ROM)　18th　2021

  6. Numerical Investigation on Possibilities of Liquid Ammonia Spray Combustion in the Gas Turbine-like Combustors

    SOMARATHNE Kapuruge Don Kunkuma Amila, HAYAKAWA Akihiro, KOBAYASHI Hideaki

    燃焼シンポジウム講演論文集(CD-ROM)　58th　2020

  7. カーボンフリーエネルギーキャリア利用における科学と技術

    小林秀昭, 橋本望, 小原拓, 内一哲哉, 高木敏行, 丸田薫, 中村寿, 早川晃弘, 渡邉豊

    東北大学流体科学研究所共同利用・共同研究拠点流体科学国際研究教育拠点活動報告書　2017　199‐200　2019/02

  8. Effect of NH3 Addition into CH4/air Swirl Flames on NO Emission Characteristics

    SOMARATHNE Kapuruge Don Kunkuma Amila, HAYAKAWA Akihiro, KOBAYASHI Hideaki

    燃焼シンポジウム講演論文集(CD-ROM)　57th　2019

  9. Dependence of unburnt ammonia on combustor inlet temperature of ammonia combustor of micro gas turbine

    倉田修, 壹岐典彦, 井上貴博, 松沼孝幸, 辻村拓, 古谷博秀, 河野雅人, 新井啓介, OKAFOR Ekenechukwu Chijioke, 早川晃弘, 小林秀昭

    日本機械学会動力・エネルギー技術シンポジウム講演論文集(CD-ROM)　24th　2019

    ISSN： 2424-2950

  10. Effect of Wall Heat Transfer on Emission Characteristics of Ammonia/air Swirling Flames in a Gas Turbine-like Combustor

    SOMARATHNE Kapuruge Don Kunkuma Amila, HAYAKAWA Akihiro, KOBAYASHI Hideaki

    Proceedings. International Conference on Flow Dynamics (CD-ROM)　15th　2018

  11. Effect of Wall Quenching of a Gas Turbine-like Combustor on Emission Characteristics of Ammonia/air Non-premixed Swirling Flames

    SOMARATHNE Kapuruge Don Kunkuma Amila, HAYAKAWA Akihiro, KOBAYASHI Hideaki

    燃焼シンポジウム講演論文集　56th　2018

  12. Research and Development of Ammonia Combustion, Low-NOx, Rich-lean, Gas Turbine Combustor

    倉田修, 壹岐典彦, 井上貴博, 辻村拓, 古谷博秀, 河野雅人, 新井啓介, Ekenechukwu Chijioke Okafor, 早川晃弘, 小林秀昭

    燃焼シンポジウム講演論文集　56th　2018

  13. アンモニア燃焼ガスタービンにおける低NOx Rich-lean燃焼器の研究開発

    壹岐典彦, 倉田修, 井上貴博, 松沼孝幸, 辻村拓, 古谷博秀, 河野雅人, 新井啓介, OKAFOR Ekenechukwu Chijioke, 早川晃弘, 小林秀昭

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

    ISSN： 2432-6739

  14. A Study of Cavity Flame Holder with a Pylon in Supersonic Flow

    60　5p　2016/09/06

    Publisher: 日本航空宇宙学会

    ISSN： 1884-1945

  15. カーボンフリーアンモニア燃焼

    小林秀昭, 早川晃弘

    58　(183)　41-48　2016/02/15

    DOI： 10.20619/jcombsj.58.183_41 　

  16. F134 Laminar Combustion Characteristics of Methane/ammonia/air Premixed Flames

    Ichikawa Akinori, Kitagawa Yuichi, Kudo Taku, Hayakawa Akihiro, Kobayashi Hideaki

    Procee[d]ings of Thermal Engineering Conference　2015　"F134-1"-"F134-2"　2015/10/23

    Publisher: The Japan Society of Mechanical Engineers

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    Hydrocarbon-ammonia combustion is a potential phase-in of CO_2 reduction for large scale energy systems. In this study, chemiluminescence spectrum of flame, laminar burning velocity and exhaust gas of methane/ammonia/air premixed flames were investigated varying with ammonia concentration in fuel. NH_2 α band spectrum was observed and flames became orange with the increase in the amount of ammonia in fuel. The laminar burning velocity decreased with the increase in ammonia in fuel. CO concentration in burned gas decreased with the increase in ammonia in fuel. NO concentration rapidly increased when ammonia ratio increased from 0 % to 5 %, then NO concentration gradually changes when ammonia ratio increased furthermore.

  17. I125 Combustion Characteristics of Ammonia/air Premixed Flames with Hydrogen Addition

    Kitagawa Yuichi, Ichikawa Akinori, Kudo Taku, Hayakawa Akihiro, Kobayashi Hideaki

    Procee[d]ings of Thermal Engineering Conference　2014　"I125-1"-"I125-2"　2014/11/08

    Publisher: The Japan Society of Mechanical Engineers

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    Ammonia is expected as a hydrogen energy carrier and a carbon-free fuel. Because the combustion intensity of ammonia is weaker than that of hydrocarbon fuels, improvement of combustion intensity is required. In this study, combustion characteristics of ammonia/hydrogen/air flames were investigated using a constant volume combustion chamber and a nozzle-type burner. The laminar burning velocity monotonically increases with hydrogen addition. The Markstein length varies non-monotonically with hydrogen addition. The scale of turbulent flame front wrinkles of smaller hydrogen concentration flames are larger than that of higher ones because of thicker flame thickness of smaller hydrogen concentration flame.

  18. G0610306 Laminar Flame Characteristics of Spherically Propagating Premixed Ammonia/air Flames

    MIMOTO Rentaro, HAYAKAWA Akihiro, GOTO Takashi, KUDO Taku, KOBAYASHI Hideaki

    Mechanical Engineering Congress, Japan　2014　"G0610306-1"-"G0610306-5"　2014/09/07

    Publisher: The Japan Society of Mechanical Engineers

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    Ammonia is expected to be not only as a hydrogen energy carrier but also as a carbon-free fuel. However, few studies of ammonia flame have been studied because of its lower combustion intensities. In this study, laminar burning velocity and Markstein length of ammonia/air premixed flames were experimentally evaluated from spherically propagating laminar flames. Equivalence ratios were varied from 0.7 to 1.3 and initial mixture pressure was set to 0.1 MPa. Spherically propagating laminar flames in a constant volume combustion chamber were observed by Schlieren photography with a high-speed camera. As a result, unstretched laminar burning velocities obtained in this study were slower than 8 cm/s for all examined equivalence ratios. The Markstein length increased with the increase in equivalence ratio. At the conditions of equivalence ratio of 0.8 and 0.9, Markstein lengths were negative. The numerical simulation using CHEMKIN-PRO with detailed reaction mechanisms were also performed. The reaction mechanisms must be improved in order to predict the unstretched laminar burning velocity of ammonia/air premixed flames.

  19. A223 Turbulent Premixed Flame Structure of Propanol Isomers in a High-pressure Environment

    Uchida Tomohiro, Souyoshi Shungo, Kudo Taku, Hayakawa Akihiro, Kobayashi Hideaki, Kadowaki Satoshi

    Procee[d]ings of Thermal Engineering Conference　2013　311-312　2013/10/18

    Publisher: The Japan Society of Mechanical Engineers

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    For practical application of high carbon number biofuel, experiments of propanol isomers and propane turbulent premixed flame using OH-PLIF measurement were performed in a high pressure environment. The local flame surface density, Σ_<local>, for each fuel was analyzed from instantaneous turbulent flame images of cross-section. The results of Σ_<local> analysis indicated differences of intrinsic flame instability for 1-propanol, 2-propanol and propane. In addition, numerical simulations of propanol and propane laminar premixed flames using CHEMKIM-PRO were carried out to clarify the relationship between chemical reaction and flame instability. It was presumed that turbulent flame structure is affected by the diffusive thermal effects related to concentrations of the intermediate species, C_2H_2 and C_2H_4, depending of fuels and differences in dissociation reaction pathway.

  20. G061056 Effects of Equivalence Ratio on Flame Surface Density of Spherically Propagating Premixed Flame

    WAKABAYASHI Yotaro, TSUKAMOTO Taiki, HAYAKAWA Akihiro, NAGANO Yukihide, KITAGAWA Toshiaki

    Mechanical Engineering Congress, Japan　2013　"G061056-1"-"G061056-5"　2013/09/08

    Publisher: The Japan Society of Mechanical Engineers

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    Flame front area of turbulent flame is considered to be dominant to turbulent burning velocity. Flame surface density is an important parameter taken into consideration in some turbulent combustion models. Most of previous studies regarding flame surface density were based on burner flames or numerical investigations. Only a few studies have been carried out on this parameter of spherically propagation flames. In this study, flame surface density of spherically propagating flame was examined. The cross-sectional images of spherically propagating flame were obtained by Mie scattered laser tomograph technique. Burning velocities and configuration of the flames were investigated for iso-octane/air mixtures at equivalence ratio of 0.8,1.0, 1.4. The ratio of turbulent burning velocity increased with the increase in equivalence ratio. The perimeter of the cross-sectional images of the flame increased with equivalence ratio. However, the flame surface density did not vary with equivalence ratio.

  21. 803 Observation of Spherically Propagating Premixed Turbulent Flame by Dual Plane Laser Sheets

    HAYAKAWA Akihiro, KUBO Toshihiko, TSUKAMOTO Taiki, NAGANO Yukihide, KITAGAWA Toshiaki

    2013　(66)　239-240　2013/03/13

    Publisher: The Japan Society of Mechanical Engineers

  22. 804 Turbulent Burning Velocity of Spherically Propagating Premixed Flame based on Mean Progress Variable

    HAYAKAWA Akihiro, KUBO Toshihiko, TSUKAMOTO Taiki, NAGANO Yukihide, KITAGAWA Toshiaki

    2013　(66)　241-242　2013/03/13

    Publisher: The Japan Society of Mechanical Engineers

  23. C213 Variations of Flame Surface Density of Spherically Propagating Premixed Turbulent Flame with Flame Propagation and Pressure

    Hayakawa Akihiro, Kubo Toshihiko, Tanaka Shiori, Nagano Yukihide, Kitagawa Toshiaki

    Procee[d]ings of Thermal Engineering Conference　2012　361-362　2012/11/16

    Publisher: The Japan Society of Mechanical Engineers

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    Flame front area of turbulent flame is considered to be the dominant factor to turbulent burning velocity. The flame surface density is an important parameter and is considered in turbulent combustion models. The flame surface density of spherically propagating premixed turbulent flame was experimentally obtained by Mie scattered laser tomography technique. The peak value of flame surface density decreased as flame propagated at the same innitial mixture pressure. The values of flame surface density at elevated pressures were larger than that ato 0.10 MPa Both large and small scale wrinkles may affect the value of flame surface density.

  24. J054013 Geometric Characteristics of Flame Front Shape of Spherically Propagating Premixed Turbulent Flame

    HAYAKAWA Akihiro, KUBO Toshihiko, MIKI Yukito, NAGANO Yukihide, KITAGAWA Toshiaki

    Mechanical Engineering Congress, Japan　2012　"J054013-1"-"J054013-5"　2012/09/09

    Publisher: The Japan Society of Mechanical Engineers

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    Turbulent burning velocity of spherically propagating premixed turbulent flame keeps increasing during flame propagation. The flame front area is considered to be the most dominant factor to turbulent burning velocity. Thus, it is important to evaluate the flame front area during flame propagation in order to clarify the variation of turbulent burning velocity with flame propagation. However, to evaluate the turbulent flame front area quantitatively is generally difficult because of the convoluted structure of turbulent flame front. The fractal analysis is one of the techniques to deal with the convoluted figures. In this study, the fractal analysis was conducted for stoichiometric spherically propagating premixed turbulent iso-octane/air flames. The laser tomograph technique was adopted to obtain the cross-sectional images of turbulent flames. The fractal characteristics, such as fractal dimension, inner-cutoff and outer-cutoff scales, were obtained. Then, the correlation (ε_o/ε_i)^<D_3-2> (1-KaMa) of turbulent burning velocity was investigated. Here, ε_o, ε_i,D_3, Ka and Ma are outer-cutoff scale, inner-cutoff scale, fractal dimension, turbulence Karlovitz number and Markstein number, respectively. The correlation (ε_o/ε_i)^<D_3-2> (1-KaMa) of turbulent burning velocity was well related to the measured value of turbulent burning velocity in the examined conditions of this study

  25. 1010 Influence of Turbulence on flame front shape of spherically propagating turbulent premixed flames

    KUBO Toshihiko, HAYAKAWA Akihiro, MIKI Yukito, NAGANO Yukihide, KITAGAWA Toshiaki

    2012　(65)　365-366　2012/03/16

    Publisher: The Japan Society of Mechanical Engineers

  26. E125 The Flame Front Shapes of Spherically Propagating Turbulent Premixed Flames and their Variation with Equivalence Ratio

    Hayakawa Akihiro, Miki Yukito, Kubo Toshihiko, Nagano Yukihide, Kitagawa Yoshiaki

    Procee[d]ings of Thermal Engineering Conference　2011　115-116　2011/10/28

    Publisher: The Japan Society of Mechanical Engineers

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    Burning velocities and configuration of turbulent propagating flames were investigated for iso-octane/air mixtures at equivalence ratios of 0.8, 1.0 and 1.4. The laser tomography was adopted to obtain the cross-sectional images of turbulent flames. The flame front area was evaluated using the perimeter of the cross-sectional image of turbulent flame. The flame brush thickness was also examined. The normalized perimeter of the cross-sectional turbulent flame image was found not to vary so much with equivalence ratio at a constant turbulence intensity, although the ratio of turbulent burning velocity to unstretched laminar burning velocity increased with equivalence ratio. On the other hand, flame brush thickness seemed to vary slightly with equivalence ratio.

  27. J056042 Study on Turbulent Propagating Flames with Effective Turbulence Intensity

    HAYAKAWA Akihiro, MIKI Yukito, TOMARI Keiichiro, NAGANO Yukihide, KITAGAWA Toshiaki

    Mechanical Engineering Congress, Japan　2011　"J056042-1"-"J056042-5"　2011/09/11

    Publisher: The Japan Society of Mechanical Engineers

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    Turbulent flame front area is considered as the most dominant factor of turbulent burning velocity. Therefore, it is important to investigate the contribution of the flame front area to turbulent burning velocity. In this study, turbulent explosions of iso-octane/air mixtures at equivalence ratios of 0.8 and 1.4 were carried out. The laser tomography was adopted to obtain the cross-sectional image of turbulent flame. The flame front area was evaluated using the perimeter of the cross-sectional image of turbulent flame. The ratio of turbulent flame perimeter to circle perimeter of mean radius increased with the increase in the ratio of effective turbulence intensity to unstretched laminar burning velocity. The ratios of perimeter of turbulent flame to the mean circle perimeter of both equivalence ratios had no significant difference. However, the ratios of turbulent burning velocity to unstretched laminar burning velocity at equivalence ratio of 1.4 were larger than those of 0.8. This result was considered to be due to the thermo-diffusive effects.

  28. I13 Influence of Energy Spectrum and Scales of Turbulence on Burning Velocity of Spherically Propagating Premixed Turbulent Flame

    HAYAKAWA Akihiro, MIKI Yukito, NAGANO Yukihide, KITAGAWA Toshiaki

    2011　(64)　315-316　2011/03/17

    Publisher: The Japan Society of Mechanical Engineers

  29. E113 Study of Turbulent Burning Velocity of Iso-octane/Air Mixtures at Fixed Turbulence Karlovitz Number

    Hayakawa Akihiro, Miki Yukito, Hirata Yoshiharu, Nagano Yukihide, Kitagawa Toshiaki

    Procee[d]ings of Thermal Engineering Conference　2010　123-124　2010/10/29

    Publisher: The Japan Society of Mechanical Engineers

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    Spherically propagating laminar and turbulent flames were studied using iso-octane/air mixtures with and without dilution. In order to examine the thermo-diffusive effects solely separating them from the effects of flame stretch, turbulent burning velocities were compared at constant flame stretch factors. The mean flame stretch factor acting on turbulent flame front may be represented by the turbulence Karlovitz number. Thus, turbulent explosions were carried out at fixed turbulence Karlovitz numbers. As a result, the ratio of turbulent burning velocity to unstretched laminar one increased with decreasing Markstein number. Especially, it changed stepwise around Markstein number of zero.

  30. E141 Combustion Properties of Coal Gasification Gas for IGCC Power Generation System with CO_2 Capture

    Nagano Yukihide, Kado Kunihiro, Takeo Tomohiro, Hayakawa Akihiro, Kitagawa Toshiaki

    Procee[d]ings of Thermal Engineering Conference　2010　143-144　2010/10/29

    Publisher: The Japan Society of Mechanical Engineers

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    Combustion properties of coal gasification gas with CO_2 dilution were investigated for a newly proposed IGCC power generation system with CO_2 capture. In this system, the gasification gas is burned under high CO_2 concentration atmosphere. The laminar and turbulent burning velocities were measured for outwardly propagating stoichiometric H_2/O_2/CO_2 flames under the condition of constant flame temperature of 1300, 1500, 1700 and 2135℃ with initial mixture pressure, P_i of 0.10 and 0.25MPa. Increase in the turbulence Karlovitz number and decrease in the Markstein number by the CO_2 dilution might cause the increase in the ratios of the turbulent burning velocities at the flame radius 30mm, u_<tn(30mm)> to the unstretched laminar burning velocities, u_l of H_2/O_2/CO_2 flames.

  31. 1001 Influence of thermo-diffusive effects on turbulent propagating iso-octane / inert gas flames / air

    YAMASHITA Shimpei, HAYAKAWA Akihiro, KUROKAWA Yohei, KOBAYASHI Shoichi, KITAGAWA Toshiaki

    2010　(63)　355-356　2010/03/15

    Publisher: The Japan Society of Mechanical Engineers

  32. A124 Relationship between effective turbulence intensity and burning velocity of turbulent propagating flame

    Hayakawa Akihiro, Kitagawa Toshiaki

    Procee[d]ings of Thermal Engineering Conference　2009　15-16　2009/11/06

    Publisher: The Japan Society of Mechanical Engineers

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    Turbulent burning velocity of spherically propagating flame kept increasing with flame propagation. The range of scale of turbulent eddy effective to the turbulent burning velocity might be changing during the flame propagation. Small flame kernel is wrinkled only by the small scales of turbulence. As the kernel continues to grow, it becomes progressively wrinkled by the larger length scales of turbulence. The turbulence that affects to flame kernel effectively was called "effective turbulence intensity" in this study. Energy spectrum of turbulence was obtained from PIV measurements. Effective turbulence intensity was evaluated quantitatively from energy spectrum of turbulence. Then relationship between turbulent burning velocity and effective turbulence intensity were investigated.

  33. F217 Effects of Pressure on Laminar and Turbulent Burning Velocities of Ethanol Premixed Flames

    OHARA Kazutaka, TSUKIKAWA Masayoshi, ARAKI Yousuke, HAYAKAWA Akihiro, KOBAYASHI Shoichi, KITAGAWA Toshiaki

    National Symposium on Power and Energy Systems　2009　(14)　507-510　2009/06/28

    Publisher: The Japan Society of Mechanical Engineers

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    Spherically propagating laminar and turbulent flames at elevated pressures in a large volume bomb were studied for ethanol-air mixtures. Experiments were carried out at the equivalence ratio 0.8, 1.0 and 1.4 varying the initial pressure from 0.10 to 0.50MPa. Turbulence intensity of the mixture was 0.80 and 1.59m/s. The unstretched laminar burning velocity, U_l decreased as the initial pressure increased. The ratio of the turbulent burning velocity to U_l increased with increasing the ratio of turbulence intensity to U_l and turbulence Karlovitz number. This burning velocity ratio was large for rich flames. Thermo-diffusive effects might be more influential to rich ethanol flames because of the small Lewis number. This burning velocity ratio was also found to increase with increasing initial pressure.

  34. I22 Effects of Pressure on Ethanol Laminar and Turbulent Premixed Flames

    OHARA Kazutaka, TSUKIKAWA Masayoshi, ARAKI Yousuke, HAYAKAWA Akihiro, KOBAYASHI Shoichi, KITAGAWA Toshiaki

    2009　(62)　271-272　2009/03/18

    Publisher: The Japan Society of Mechanical Engineers

  35. I24 Effects of CO_2 Dilution on Laminar and Turbulent Combustion Properties of Iso-octane Premixed Flames

    HAYAKAWA Akihiro, MARUYAMA Kosuke, KUROKAWA Yohei, KOBAYASHI Shoichi, KITAGAWA Toshiaki

    2009　(62)　275-276　2009/03/18

    Publisher: The Japan Society of Mechanical Engineers

  36. J14 Effects of Pressure on Laminar and Turbulent Burning Velocities of Iso-octane Premixed Propagating Flames

    MARUYAMA Kousuke, KITAGAWA Toshiaki, FURUKAWA Kouichi, KADO Kunihiro, HAYAKAWA Akihiro

    2008　(61)　319-320　2008/03/19

    Publisher: The Japan Society of Mechanical Engineers

Show all ︎Show first 5

Presentations 101

  1. アンモニア燃焼用低NOｘRich-leanガスタービン燃焼器の研究開発

    倉田修, 壹岐典彦, 井上貴博, 辻村拓, 古谷博秀, 河野雅人, 新井啓介, E.C. Okafor, 早川晃弘, 小林秀昭

    第56回燃焼シンポジウム　2018/11/16

  2. Efficient Low NOx Combustion Strategies for Ammonia-methane Fuel a Micro Gas Turbine Combustor

    E.C. Okafor, A. Hayakawa, R. Rattanasupapornsak, A. Hayakawa, T. Kudo, O. Kurata, N. Iki, H. Kobayashi

    第56回燃焼シンポジウム　2018/11/14

  3. Effect of Wall Quenching of a Gas Turbine- Like Combustor on Emission Characteristics of Ammonia/air Non-Premixed Swirling Flames

    K.D.K.A. Somarathne, A. Hayakawa, H. Kobayashi

    第56回燃焼シンポジウム　2018/11/14

  4. A Study of Premixed Flames interacted with Turbulent Shear Flows

    福井陽一, 佐々木央, 工藤琢, 早川晃弘, 小林秀昭

    第56回燃焼シンポジウム　2018/11/14

  5. Effects of CO2 Concentration on Flame Propagation Characteristics of CH4/CO2/air Laminar Premixed Flames under Various Equivalence Ratios and Pressures International-presentation

    A. Hayakawa, E.C. Okafor, W. Anggono

    Proceedings of the Fifteenth International Conference on Flow Dynamics (ICFD2018)　2018/11/08

  6. Effect of Wall Heat Transfer on Emission Characteristics of Ammonia/air Swirling Flames in a Gas Turbine?like Combustor International-presentation

    K. D, K. A. Somarathne, A. Hayakawa, H. Kobayashi

    Proceedings of the Fifteenth International Conference on Flow Dynamics (ICFD2018)　2018/11/08

  7. Emission Characteristics and the Structure of Ammonia-Air Flames in a Micro Gas Turbine Swirl Combustor International-presentation

    E. C. Okafor, R. Rattanasupapornsak, K. D, K. A. Somarathne, A. Hayakawa, T. Kudo, O. Kurata, N. Iki, H. Kobayashi

    Proceedings of the Fifteenth International Conference on Flow Dynamics (ICFD2018)　2018/11/08

  8. Experimental Study of Turbulent Flame Propagation of Ammonia/Air Mixture in a Fan-Stirred Closed Vessel International-presentation

    R. Ichimura, K. Hadi, N. Hashimoto, A. Hayakawa, H. Kobayashi, O. Fujita

    Proceedings of the Fifteenth International Conference on Flow Dynamics (ICFD2018)　2018/11/08

  9. Flame Front Structure of Ammonia/air Turbulent Premixed Flames in Swirling Flows under Various Pressures International-presentation

    A. Hayakawa, M. Tsukamoto, K. D, K. A. Somarathne, T. Kudo, H. Kobayashi

    Proceedings of the Fifteenth International Conference on Flow Dynamics (ICFD2018)　2018/11/08

  10. Burnt Gas Characteristics of Swirl Stabilized Ammonia/air Turbulent Premixed Flames for Various Mixture Inlet Velocity International-presentation

    M. Tsukamoto, A. Hayakawa, K. D, K. A. Somarathne, T. Kudo, H. Kobayashi

    Proceedings of the Fifteenth International Conference on Flow Dynamics (ICFD2018)　2018/11/07

  11. Effect of Shear Flow Turbulence on Premixed Flame International-presentation

    H. Sasaki, Y. Fukui, T. Kudo, A. Hayakawa, H. Kobayashi

    Proceedings of the Fifteenth International Conference on Flow Dynamics (ICFD2018)　2018/11/07

  12. Burning Velocity and Flame Structure of Ammonia/Hydrogen/Air Turbulent Premixed Flames at Elevated Pressures International-presentation

    A. Ichikawa, T. Kudo, A. Hayakawa, T. Kudo, H. Kobayashi

    Proceedings of the Fifteenth International Conference on Flow Dynamics (ICFD2018)　2018/11/07

  13. Exhaust Gas Characteristics of Bio-fuel Combustion International-presentation

    T. Abe, K. Takahashi, T. Kudo, A. Hayakawa, H. Kobayashi

    Proceedings of the Fifteenth International Conference on Flow Dynamics (ICFD2018)　2018/11/07

  14. Development of Two-dimensional Supersonic Nozzle for a Scramjet Model Combustor International-presentation

    T. Yamaguchi, T. Hizawa, T. Kudo, A. Hayakawa, H. Kobayashi

    Proceedings of the Fifteenth International Conference on Flow Dynamics (ICFD2018)　2018/11/07

  15. Two Stage Ammonia Combustion in a Gas Turbine like Combustor for Simultaneous NO and unburnt Ammonia Reductions International-presentation

    A. Hayakawa, K.D.K.A. Somarathne, M. Tsukamoto, T. Kudo, H. Kobayashi

    NH3 Topical Conference　2018/10/31

  16. Development of Low-NOx Combustor of Micro Gas Turbine Firing Ammonia Gas International-presentation

    O. Kurata, N. Iki, T. Inoue, T. Matsunuma, T. Tsujimura, H. Furutani, M. Kawano, K. Arai, E.C. Okafor, A. Hayakawa, H. Kobayashi

    NH3 Topical Conference　2018/10/31

  17. 旋回流中に保炎されたアンモニア/空気乱流予混合火炎の火炎構造

    早川晃弘, 塚本真章, K.D.K.A. Somarathne, 工藤琢, 小林秀昭

    日本機械学会 熱工学コンファレンス2018　2018/10/20

  18. Rich-lean Low-NOx Combustor for Micro Gas Turbine Firing Ammonia Gas International-presentation

    O. Kurata, N. Iki, T. Inoue, T. Matsunuma, T. Tsujimura, H. Furutani, M. Kawano, K. Arai, E.C. Okafor, A. Hayakawa, H. Kobayashi

    Asian Congress on Gas Turbines　2018/08/24

  19. Science and technology of ammonia combustion International-presentation

    H. Kobayashi, A. Hayakawa, K.D.K.A. Somarathne, E.C. Okafor

    37th International Symposium on Combustion　2018/08/03

  20. Development of wide range operable, rich-lean low-NOx combustor for NH3 fuel gas-turbine power generations International-presentation

    O. Kurata, N. Iki, T. Inoue, T. Matsunuma, T. Tsujimura, H. Furutani, M. Kawano, K. Arai, E.C. Okafor, A. Hayakawa, H. Kobayashi

    37th International Symposium on Combustion　2018/08/03

  21. Towards the development of an efficient low-NOx ammonia combustor for a micro gas turbine International-presentation

    E.C. Okafor, K.D.K.A. Somarathne, A. Hayakawa, T. Kudo, O. Kurata, N. Iki, H. Kobayashi

    37th International Symposium on Combustion　2018/08/03

  22. Research of Ammonia Combustor for Micro Gas Turbine Power Generation and High Temperature Resistance of Materials International-presentation

    N. Iki, O. Kurata, T. Inoue, T. Matsunuma, T. Tsujimura, H. Furutani, M. Kawano, E.C. Okafor, A. Hayakawa, H. Kobayashi

    37th International Symposium on Combustion　2018/08/02

  23. Application of OH(2,0) band excited planar laser-induced fluorescence measurement to high pressure H2/O2 co-axial jet diffusion flames International-presentation

    Y. Higuchi, K. Takeuchi, Y. Nunome, K. Sasaki, S. Tomioka, T. Kudo, A. Hayakawa, H. Kobayashi

    37th International Symposium on Combustion　2018/08/02

  24. Turbulent combustion characteristics of ammonia/hydrogen/air premixed flames at high pressure International-presentation

    A. Ichikawa, A. Hayakawa, T. Kudo, H. Kobayashi

    37th International Symposium on Combustion　2018/07/31

  25. Investigation of methane-ammonia chemistry from premixed and diffusion flame structures using a counterflow configuration International-presentation

    S. Colson, Y. Hirano, T. Kudo, A. Hayakawa, H. Kobayashi, D. Escudie, C. Galizzi

    37th International Symposium on Combustion　2018/07/31

  26. Quantitative measurement of temperature in oxygen enriched CH4/O2/N2 premixed flames using Laser Induced Thermal Grating Spectroscopy (LITGS) up to 1.0MPa International-presentation

    A. Hayakawa, T. Yamagami, K. Takeuchi, Y. Higuchi, T. Kudo, S. Lowe, Y. Gao, S. Hochgreb, H. Kobayashi

    37th International Symposium on Combustion　2018/07/31

  27. The Effect of Wall Heat Loss in a Gas Turbine-like Combustor on the Emission Characteristics of Ammonia (NH3)/air Swirling Flames International-presentation

    K.D.K.A. Somarathne, E.C. Okafor, A. Hayakawa, H. Kobayashi

    37th International Symposium on Combustion　2018/07/30

  28. Development of Low NOx Combustor of Ammonia Fuel Gas Turbine Power Generations International-presentation

    O. Kurata, N. Iki, T. Inoue, T. Matsunuma, T. Tsujimura, H. Furutani, M. Kawano, K. Arai, A. Hayakawa, H. Kobayashi, E.C. Okafor

    22nd World Hydrogen Energy Conference　2018/06/18

  29. Development of Low NOx Combustor of Ammonia Fuel Gas Turbine Power Generations International-presentation

    O. Kurata, N. Iki, T. Inoue, T. Matsunuma, T. Tsujimura, H. Furutani, M. Kawano, K. Arai, A. Hayakawa, H. Kobayashi

    40th IEA Combustion Task Ledaders Meeting　2018/06/13

  30. NOx Reduction of a Swirl Combustor Firing Ammonia for a Micro Gas Turbine International-presentation

    N. Iki, O. Kurata, T. Inoue, T. Matsunuma, T. Tsujimura, H. Furutani, M. Kawano, A. Hayakawa, H. Kobayashi, E.C. Okafor

    ASME Turbo Expo 2018　2018/06/11

  31. CH4/NH3/air乱流予混合火炎の火炎構造に与える圧力およびアンモニア濃度の影響

    市川昌紀, 内藤佑次, 早川晃弘, 工藤琢, 小林秀昭

    第55回日本伝熱シンポジウム,　2018/05/30

  32. Achievement of Low NOx Emission on From Ammonia Micro Gas Turbine Combustor

    E.C. Okafor, A. Hayakawa, T. Kudo, O. Kurata, N. Iki, H. Kobayshi

    第55回日本伝熱シンポジウム,　2018/05/30

  33. Flame structure characteristics of swirl stabilized ammonia/air premixed flames International-presentation

    A. Hayakawa, M. Tsukamoto, K.D.K.A. Somarathne, T. Kudo, H. Kobayashi

    2nd European Power to Ammonia Conference　2018/05/18

  34. 水素/空気燃焼ガストーチイグナイタの噴射ガス温度推定法の検証

    山口達也, 日沢知寛, 市川太郎, 工藤琢, 早川晃弘, 小林秀昭

    日本航空宇宙学会北部支部2018年講演会ならびに第19回再使用型宇宙推進系シンポジウム　2018/03/06

  35. Laser Induced Thermal Grating Spectroscopyによる酸素富化CH4/O2/N2予混合?炎の?圧下における定量温度計測

    早川晃弘, 山上朋恭, 竹内清剛, 樋口靖浩, 工藤琢, Steven Lowe, Yi Gao, Simone Hochgreb, 小林秀昭

    日本航空宇宙学会北部支部2018年講演会ならびに第19回再使用型宇宙推進系シンポジウム　2018/03/05

  36. アンモニア燃焼ガスタービン発電装置の燃焼状態の観察

    第54回燃焼シンポジウム　2016/11/25

  37. 高圧高温火炎に対する光学計測校正バーナーの開発

    第54回燃焼シンポジウム　2016/11/25

  38. Extinction Analysis and Experiments of Methane/ammonia/air Counterflow Twin Flames

    第54回燃焼シンポジウム　2016/11/24

  39. The Effects of Pressure on Emission Reduction Characteristics of Turbulent Premixed Ammonia/air Flames Stabilized by a Swirl Burner

    第54回燃焼シンポジウム　2016/11/24

  40. Laminar Burning Velocity and Markstein Lengths of CH4-NH3-Air Premixed Flames up to Elevated Pressures

    第54回燃焼シンポジウム　2016/11/23

  41. Quantitative Temperature Measurement of High Pressure CH4/O2/N2Laminar Flames Using Laser Induced Thermal Grating Spectroscopy (LITGS)

    第54回燃焼シンポジウム　2016/11/23

  42. Gas Turbine Power Generation System firing Ammonia-Methane Mixture International-presentation

    Proceedings of the Asian Congress on Gas Turbines (ACGT2016)　2016/11/14

  43. ガスタービンにおけるアンモニア燃焼利用

    第44回日本ガスタービン学会定期講演会　2016/10/26

  44. アンモニアマイクロガスタービン燃焼器における保炎限界と燃焼排出ガス特性

    日本機械学会熱工学コンファレンス2016　2016/10/23

  45. Effect of Cavity with a Pylon on the Flame in Supersonic Flow International-presentation

    Proceedings of the Thirteenth International Conference on Flow Dynamics (ICFD2016),　2016/10/11

  46. Effects of NH3 Addition on the Laminar Burning Velocity and Markstein Length of CH4-Air Premixed Flames International-presentation

    Proceedings of the Thirteenth International Conference on Flow Dynamics (ICFD2016)　2016/10/11

  47. Flame Stabilization Limits and Emission Characteristics of an Ammonia Micro Gas Turbine Combustor International-presentation

    Proceedings of the Thirteenth International Conference on Flow Dynamics (ICFD2016),　2016/10/11

  48. Quantitative Temperature Measurement of High Pressure Flame by Using laser Induced Thermal Grating Spectroscopy (LITGS) International-presentation

    Proceedings of the Sixteenth International Symposium on Advanced Fluid Information (AFI-2016)　2016/10/11

  49. Laser Induced Thermal Grating Spectroscopy (LITGS) and Thermographic PIV for Quantitative Measurement International-presentation

    the Sixteenth International Symposium on Advanced Fluid Information (AFI-2016)　2016/10

  50. Combustion Characteristics of Ammonia/air Flames for a Model Swirl Burner and an Actual Gas Turbine Combustor International-presentation

    13th Annual 2016 NH3 Fuel Conference　2016/09/19

  51. Power generation and Flame Visualization of Micro Gas Turbine Firing Ammonia or Ammonia-Methane Mixture International-presentation

    13th Annual 2016 NH3 Fuel Conference,　2016/09/19

  52. 超音速流におけるパイロン付きキャビティー保炎器に関する研究

    第60回宇宙科学技術連合講演会　2016/09/07

  53. Numerical Investigation on Emission Reduction Characteristics of Turbulent Swirl Flames for Ammonia/air Mixture International-presentation

    36th International Symposium on Combustion　2016/08/05

  54. Flame Structure and Burning Velocity of Ammonia/Hydrogen/Air Turbulent Premixed Flames International-presentation

    36th International Symposium on Combustion　2016/08/04

  55. Extinction Characteristics of Counterflow Premixed Flames for Ammonia/air, Methane/air and Their Mixtures International-presentation

    36th International Symposium on Combustion　2016/08/02

  56. Blow-Off Limit of Ethanol Spray Flame in Swirl Flow Using a Pre-Filming Air-Blast Atomizer at Elevated Pressure International-presentation

    36th International Symposium on Combustion　2016/08/01

  57. Supersonic Combustion Using Pre-Combustion Gas Injection from a Bottom Single Hole into a Cavity Flameholder International-presentation

    36th International Symposium on Combustion　2016/08/01

  58. Micro Gas Turbine Firing Ammonia International-presentation

    roceedings of ASME Turbo Expo 2016　2016/06/17

  59. Ammonia-fired gas turbine power generation system International-presentation

    Proceedings of the 21st World Hydrogen Energy Conference 2016　2016/06/15

  60. Stabilization and Emission Characteristics of Ammonia/air Premixed Flames in Swirling Flows International-presentation

    Proceedings of the 21st World Hydrogen Energy Conference 2016　2016/06/15

  61. Numerical Investigation on the Emission Reduction Characteristics of the Turbulent Premixed Ammonia/air Flames Stabilized by a Swirl Burner

    第53回日本伝熱シンポジウム　2016/05/25

  62. Extinction Characteristics of Ammonia/Air Counterflow premixed Flames at Various Pressures International-presentation

    Proceedings of the First Pacific Rim Thermal Engineering Conference,　2016/03/16

  63. Application of OH-PLIF Measurements Using OH(2,0) Band Excitations to High Pressure H2/O2Jet Diffusion Flames International-presentation

    10th Asia-Pacific Conference on Combustion　2015/07

  64. Flame Characteristics of Ammonia/hydrogen/air Premixed Flames at Elevated Pressures International-presentation

    10th Asia-Pacific Conference on Combustion　2015/07

  65. Determination of the Entrainment and Dilution Characteristics in Confined Flames on NOx Emission

    第52回燃焼シンポジウム　2014/12

  66. Effects of Liquid Properties on Atomization Behavior and Characteristics of an Airblast Atomizer in a High Pressure Environment

    第52回燃焼シンポジウム　2014/12

  67. 高圧Ｈ2/Ｏ2噴流拡散火炎に対するＯＨ-ＰＬＩＦ計測の適用に関する研究

    第52回燃焼シンポジウム　2014/12

  68. 高圧環境における石炭改質ガス乱流予混合火炎の排出ガス特性に関する研究

    第52回燃焼シンポジウム　2014/12

  69. 高圧環境下におけるアンモニア空気予混合火炎の層流燃焼特性

    第52回燃焼シンポジウム　2014/12

  70. 超音速燃焼におけるオゾン添加による保炎性能向上に関する研究

    第52回燃焼シンポジウム　2014/12

  71. 高圧下におけるアンモニア/水素/空気予混合火炎の燃焼特性

    第25回内燃機関シンポジウム　2014/11

  72. 水素添加アンモニア/空気予混合火炎の燃焼特性に関する研究

    日本機械学会熱工学コンファレンス2014　2014/11

  73. Combustion Enhancement by Ozone Addition in Supersonic Flow International-presentation

    Eleventh International Conference on Flow Dynamics (11th ICFD 2014)　2014/10

  74. Effects of Intermediate Species on Flame Instability in Turbulent Premixed Flames of Propanol Isomers at High Pressure International-presentation

    Eleventh International Conference on Flow Dynamics (11th ICFD 2014)　2014/10

  75. Effects of Liquid Properties on Airblast Atomization in a High Pressure Environment International-presentation

    Eleventh International Conference on Flow Dynamics (11th ICFD 2014)　2014/10

  76. Experimental and Numerical Investigations of Laminar Burning Velocity of Ammonia/air Premixed Flames International-presentation

    Eleventh International Conference on Flow Dynamics (11th ICFD 2014)　2014/10

  77. Interaction between Incident Shock Wave and Pre-combustion Gas Injection from a Ramp Injector in Supersonic Flow International-presentation

    Eleventh International Conference on Flow Dynamics (11th ICFD 2014)　2014/10

  78. OH-PLIF Measurements of GH2/GO2 Diffusion Flames Using Higher Electron Excitation Bands International-presentation

    Eleventh International Conference on Flow Dynamics (11th ICFD 2014)　2014/10

  79. Effects of Ambient Pressure and Liquid Properties on Atomization Characteristics of an Airblast Atomizer International-presentation

    26th European Conference on Liquid Atomization & Spray Systems　2014/09

  80. Fundamental Characteristics of Ammonia/Air Premixed Laminar Flames International-presentation

    2014 NH3 Fuel Conference　2014/09

  81. 球状に伝播するアンモニア空気予混合火炎の層流燃焼特性

    日本機械学会2014年度年次大会　2014/09

  82. On the Role of Intermediate Species in Turbulent Premixed Combustion of Propane and Prpanol Isomers at High Pressure International-presentation

    35th International Symposium on Combustion　2014/08/08

  83. Effects of Ambient Pressure on Atomization Behavior of Airblast Atomizer International-presentation

    35th International Symposium on Combustion　2014/08/06

  84. NO Formation/Reduction Mechanisms of Ammonia/Air Premixed Laminar Flames at Various Equivalence Ratios and Ambient Pressures International-presentation

    35th International Symposium on Combustion　2014/08/06

  85. Interaction Between Pre-Combustion Gas Injection From a Ramp Injector and Incident Shockwave in Supersonic Flow International-presentation

    35th International Symposium on Combustion　2014/08/05

  86. Laminar Burning Velocity and Markstein Number of Spherically Propagating Ammonia/Air Premixed Flames International-presentation

    35th International Symposium on Combustion　2014/08/05

  87. 高圧環境におけるアンモニア空気予混合火炎からのNO生成および低減特性

    第51回日本伝熱シンポジウム　2014/05

  88. 超音速流において衝撃波干渉するキャビティー保炎器下流の火炎構造に関する研究

    日本航空宇宙学会北部支部2014年　2014/03

  89. Characteristics of Ammonia/air Laminar Premixed Flames and NO Formation/Reduction Mechanism International-presentation

    Taiwan-Japan Fuel Cell-Energy Carrier Workshop　2013/12

  90. アンモニア予混合火炎の層流燃焼速度およびNOｘ生成持性

    第51回燃焼シンポジウム　2013/12

  91. 気流噴射弁の噴霧形成過程に及ぼす雰囲気圧力の影響

    第51回燃焼シンポジウム　2013/12

  92. 高圧下におけるプロパノール異性体乱流予混合火炎の火炎構造及び不安定性に関する研究

    第51回燃焼シンポジウム　2013/12

  93. 高圧環境におけるCO/H2/CO2/O2乱流予混合火炎構造に及ぼす燃料組成の影響

    第51回燃焼シンポジウム　2013/12

  94. 高圧環境における気流噴射弁の噴霧粒径および噴霧形成過程に関する研究

    第16回微粒化アジア会議 第22回微粒化シンポジウム　2013/12

  95. 超音速流におけるランプインジェクター下流燃焼領域の衝撃波干渉に関する研究

    第51回燃焼シンポジウム　2013/12

  96. Effects of Ambient Pressure on Liquid Sheet Breakup of Airblast Atomizer International-presentation

    Tenth International Conference on Flow Dynamics　2013/11

  97. Interaction between Incident Shock Wave and Combustion Downstream of Ramp Injector in Supersonic Flow International-presentation

    Tenth International Conference on Flow Dynamics　2013/11

  98. 高圧環境におけるプロパノール異性体乱流予混合火炎の構造に関する研究

    日本機械学会熱工学コンファレンス2013　2013/10

  99. 球状伝播予混合乱流火炎の火炎面密度に及ぼす当量比の影響

    日本機械学会 2013年度年次大会大会　2013/09

  100. Experimental and Numerical Studies on Burning Velocities and Markstein Numbers on Lean Laminar H2/CH4/air Flames International-presentation

    The 9th Asia-Pacific Conference on Combustion　2013/05

  101. 球状伝播予混合乱流火炎の燃焼速度に及ぼす有効乱れ強さと火炎伸長の影響

    自動車技術会 2013年春季大会　2013/05

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Industrial Property Rights 2

  1. 低燃焼性燃料燃焼装置

    早川晃弘, 三本連太郎, 工藤琢, 小林秀昭

    Property Type: Patent

  2. スクラムジェットエンジン用燃焼装置及びスクラムジェットエンジン

    石本裕美, 小林秀昭, 工藤琢, 早川晃弘

    Property Type: Patent

Research Projects 14

  1. Advancement of quantitative laser measurement toward clarification of combustion science in an extreme condition

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Challenging Research (Exploratory)

    Institution: Tohoku University

    2024/06/28 - 2027/03/31

  2. Research and development of manufacturing, quality, transportation and combustion technology for fine bubble fuel for the transition period to a carbon-free society.

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Scientific Research (B)

    Institution: Kurume National College of Technology

    2023/04/01 - 2026/03/31

  3. Laminar flame structures and turbulent flame characteristics of ammonia flames at high temperature and high pressure conditions

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Scientific Research (B)

    Institution: Tohoku University

    2021/04/01 - 2024/03/31

  4. 高温高圧下における液体アンモニアおよびアンモニア水溶液の噴霧燃焼実現と現象解明

    小林 秀昭, 早川 晃弘

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業

    Category: 基盤研究(B)

    Institution: 東北大学

    2020/04/01 - 2023/03/31

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    本研究は，CO2を排出しない無機燃料である液体アンモニア(NH3)ならびに質量濃度47%までのアンモニア水溶液の高温高圧下における直接噴霧燃焼を実現し，減圧沸騰蒸発過程を有する噴霧燃焼の現象解明を行う．アンモニアは水素と並ぶCO2無排出燃料であると共に，水素に比較して保存や輸送が容易であるという優れた特徴を有している．高圧ボンベに貯蔵された液体アンモニアを加温・再加圧することなく直接噴霧燃焼させた場合の高温高圧下の乱流火炎構造と火炎安定条件，排ガス特性を実験的に明らかにし，アンモニアガスタービンへの応用に向けた基礎データを取得する．さらに，液体アンモニア噴霧燃焼をレファレンスとしてアンモニア水溶液の噴霧燃焼研究を行うことで，新しいカーボンフリー燃焼の学理構築に資する．令和３年度は，接線スワーラを内蔵した燃焼器において，昨年度成功した質量濃度30%までのアンモニア水溶液の常温空気およびメタン混焼による火炎安定化成功，レファレンスとして実施した600 Kまで予熱した空気流に対する液体アンモニア噴霧の火炎安定化成功を受けて，火炎安定化メカニズムを噴霧構造の観点からより詳細に明らかにする実験と数値解析を実施した．実験では，ホロコーンノズルによる減圧沸騰を生じる液体アンモニア噴霧と減圧沸騰を生じない水噴霧との微粒化過程の違いの可視化，ならびにダブルパルスレーザーの光干渉縞を利用して空間粒子密度の高い噴霧からの２次散乱光の影響を抑制してレーザートモグラフィーを可視化できるSLIPI法の実施，数値解析では，液体アンモニアの減圧沸騰を解析できる数理モデルを用いた非燃焼時の液体アンモニア噴霧構造の可視化，ならびに水素混焼によるアンモニア噴霧燃焼の３次元数値解析を実施した．

  5. Laser-induced fluorescence measurement of gas-liquid multiphase diffusion flames in high-pressure rocket combustion

    Kobayashi Hideaki

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Challenging Research (Exploratory)

    Institution: Tohoku University

    2020/07/30 - 2022/03/31

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    OH planer-laser-induced fluorescence measurement for gas-liquid multiphase hydrogen combustion at high pressure and high temperature applicable for rocket combustion was developed. OH(2,2) fluorescence band measurements were performed for gas H2/O2 diffusion flames at up to 5.0 MPa, and a clear flame structure with S/N ratio greater than 4 was obtained. OH(2,2) fluorescence band measurement was also applied to the gas-liquid multiphase hydrogen/liquid oxygen combustion at 3.0 MPa, and the flame structure could be observed with S/N ratio of about 2. In combustion experiments of methane/oxygen/nitrogen premixed flames up to 0.5 MPa with oxygen enrichment up to 60%, OH(2,0) band excitation and bi-directional LIF technique were combined for quantitative measurement of OH concentration, and good agreement was obtained with numerical analysis.

  6. Development of an innovative laser velocimetry without tracer particles and its application for various flow fields

    Hayakawa Akihiro

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Challenging Research (Exploratory)

    Institution: Tohoku University

    2018/06/29 - 2022/03/31

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    Development of laser diagnostics is essentially important to understand the combustion phenomena at extremely high pressure and high temperature environments, such as rocket motor. In this study, we focused on LITGS (Laser Induced Thermal Grating Spectroscopy) which is potential laser diagnostics available for high pressure environment is applied to the velocity measurement. The purpose of this study is to develop the velocity measurement method without tracer particles based on LITGS. Towards the objectives, we developed signal analysis method using FFT and the detection method of frequency modulation using heterodyne detection. The results obtained in this study are the fundamental technique for velocity measurement using LITGS with no tracer particles.

  7. Advancement and application of LITGS for quantitative temperature measurement of combustion in an extreme condition

    Hayakawa Akihiro

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Young Scientists (A)

    Institution: Tohoku University

    2017/04/01 - 2020/03/31

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    Rocket combustion is a representative combustion phenomena under an extreme condition because the orders of pressure and temperature are 10 MPa and 3000 K, respectively. Combustion measurement for such extreme condition is generally difficult using conventional laser diagnostics. In this study, it was succeeded quantitative temperature measurement of oxygen enriched methane/oxygen/nitrogen premixed flames up to 1.0 MPa using Laser Induced Thermal Grating Spectroscopy (LITGS) which is promising laser diagnostics available for high pressure combustion. In addition, it is suggested that the chromatic aberration of the crossing lens used in LITGS optics and laser intensity of the pump beam are important for the accuracy of temperature measurement using LITGS.

  8. Turbulent combustion characteristics of C3 and C4 mixed alcohol biofuel isomers in a high-pressure and high-temperature environment

    Kobayashi Hideaki

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Scientific Research (B)

    Institution: Tohoku University

    2017/04/01 - 2020/03/31

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    Combustion characteristics of C3 and C4 alcohol isomer were elucidated in a high-pressure and high-temperature environment. First, a heat release path analysis was performed and it was found that CH2O is the predominant intermediate species with high enthalpy in flame structure. By using OH-PLIF, it was proven that flame surface density for n-propanol flame is smaller than that of iso-propanol flame, indicating suppression of intrinsic flame instability in n-propanol flame. Moreover, CH2O-PLIF in terms of relationship between local flame curvature and Full-Width-Half-Maximum of CH2O profiles in a high-pressure and high-temperature environment shows that for FWHM for n-propanol flame is larger than that of iso-propanol flame in negative curvature region. The increase in FWHM of the CH2O profile suppresses the intrinsic flame instability, meaning that the theoretical prediction in terms of the effect of diffusion of intermediate species with high enthalpy was proven in this study.

  9. Spectroscopic development of laser-induced fluorescence method using higher energy band excitation for rocket combustion diagnostics

    KOBAYASHI Hideaki

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Challenging Exploratory Research

    Institution: Tohoku University

    2015/04/01 - 2017/03/31

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    In order to achieve OH-Planar Laser-Induced Fluorescence (OH-PLIF) measurements to rocket combustion which emits intense chemiluminescence, OH(2,0) band excited OH-PLIF method was developed in this study. The OH(2,1) band fluorescence was detected effectively by eliminating the interference of intense OH(0,0) band chemiluminescence, and the images of two-dimensional instantaneous OH distribution in H2/O2 jet diffusion flames were successfully acquired up to 5.9 MPa. Moreover, a calibration burner capable of adapting to high pressure and temperature flame conditions was designed to establish the quantitative optical measurement methods for rocket combustion. The oxygen-enriched CH4/O2/N2 laminar quasi one-dimensional flames were stabilized on the burner up to 0.49 MPa, with maximum flame temperature simulated to be higher than 2900 K. From these results, the primal requirements of the calibration burner were sufficiently archived.

  10. Premixed turbulent combustion characteristics taking into account the relative scales of flame and turbulence

    Hayakawa Akihiro, KOBAYASHI Hideaki

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Young Scientists (B)

    Institution: Tohoku University

    2014/04/01 - 2017/03/31

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    In order to clarify the effects of flame and turbulence scales on premixed combustion characteristics, turbulent combustion experiments were carried out using nozzle burners being outlet diameters of 14 mm, 20 mm, 40 mm and 60 mm under various mixture pressure conditions. Flame front structures were observed by OH-PLIF. The flame front wrinkling increased with an increase in burner outlet diameter. The turbulent burning velocity increased with an increase in turbulence intensity. In addition, it was clarified that the turbulent burning velocity also increased with an increase in the burner outlet diameter. Since the turbulent burning velocity of spherically propagating premixed turbulent flame increases with an increase in flame scale during flame propagation, the similar trend was also observed in the burner stabilized turbulent flame.

  11. Turbulent combustion mechanism and emission characteristics of next-generation C4-biofuel isomers in a high-pressure and high-temperature environment

    KOBAYASHI Hideaki

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Scientific Research (B)

    Institution: Tohoku University

    2014/04/01 - 2017/03/31

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    To explore the turbulent combustion mechanism of next-generation C4-biofuel isomers in a high-pressure and high-temperature environment, OH-PLIF for n-Butanol and iso-Butanol flames has been performed at pressure up to 1.0 MPa. It was found that in the regime of low turbulent intensity, maximum flame surface density of n-Butanol flame is smaller than that of iso-Butanol flame, indicating an isomer effects of biofuels at high pressure related to local structure of Butanol flames. Simultaneous measurement of NO-PLIF and OH-PLIF has been also succeeded and agreement with numerical analysis in terms of strong diffusion of NO has been confirmed. For four kinds of isomer fuels of Butanol and Butane, measurement of CO and NO emissions has been performed. CO and NO emissions from Butanol flame is weak because of oxygen containing effects, while NO emission from n-Butane flame is strongest, the mechanism being investigated based on reaction path analysis using detail chemistry.

  12. Flame structure and flame stabilization mechanism of oxygen jet diffusion flame in a high-pressure environment

    KOBAYASHI Hideaki, HAYAKAWA Akihiro

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Challenging Exploratory Research

    Institution: Tohoku University

    2012/04/01 - 2014/03/31

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    To develop safely operation method and designing mixing apparatuses for chemical plants, which mixes pure oxygen and combustible gases, characteristics of oxygen jet diffusion flames and flame stability limits in a high-pressure environment were performed. Both coaxial jet diffusion flames and transversal jet diffusion flames for pure oxygen jet in a main fuel flow were examined. Methane was used as a fuel. Results showed that, in the case of the coaxial jet flames, oxygen jet velocity is predominant for the flame stabilization and small vortexes formed at the lip of the jet tube enhance the flame stabilization. In the case of the transversal oxygen jet flames, the flow which reaches to the opposite wall plays an important role of flame stabilization, as well as flame oscillation occurs near the injection wall caused by the interaction between heat loss to the wall and high heat release in thin boundary layer at high pressure, leading to the total blow out of the flame.

  13. Turbulent combustion mechanism of isomer bio-fuels in a high-pressure, high-temperature environment

    KOBAYASHI Hideaki, HAYAKAWA Akihiro

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Scientific Research (B)

    Institution: Tohoku University

    2011/04/01 - 2014/03/31

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    For the fundamental combustion research of isomer biofuels, experiments of propanol isomers and propane turbulent premixed flame using OH-PLIF were performed in a high pressure environment. The local flame surface density for each fuel was analyzed from instantaneous turbulent flame images of cross-section. The results of the flame surface density analysis indicated differences of intrinsic flame instability for 1-propanol, 2-propanol and propane. Numerical simulations of intrinsic flame instability using a two-step reaction model as well as 1-D laminar flames using detail chemistry for propanol and propane/air mixtures were carried out to clarify the relationship between chemical reaction and flame instability. It was clarified that turbulent flame structure is highly affected by the diffusive thermal effects of C2 intermediate species, which depends on the isomer fuels and differences in dissociation reaction pathway.

  14. 圧力が予混合乱流火炎伝播特性に及ぼす影響

    早川 晃弘

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業

    Category: 特別研究員奨励費

    Institution: 九州大学

    2010 - 2012

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    本年度は,主に以下の二点について検討を行った, 一点目として,乱流火炎形状に及ぼす乱流Karlovitz数乱流Reynolds数および乱れ強さの影響について詳細に検討を行った.昨年度までの研究において,混合気初期圧力を変化させた場合,乱流Reynolds数や乱れ強さと層流燃焼速度の比なども同時に変化していた.そこで本年度は,乱流Reynolds数,乱流Karlovitz数および乱れ強さと層流燃焼速度の比を一定としたまま混合気初期圧力を変化させ,その際の乱流燃焼速度や火炎面形状について検討を行った.その結果,乱流Reynolds数を一定としたまま混合気初期圧力を高くした場合,混合気初期圧力が高くなるにつれて火炎面の大きな変形が小さくなるため,乱流火炎断面周長が短くなることが明らかとなった,また,乱れ強さと層流燃焼速度との比を一定としたまま混合気初期圧力を変化させた場合,混合気初期圧力が高くなるにつれて,火炎面に細かい凹凸が生じ,これにより乱流火炎断面周長が長くなることが明らかとなった. 二点目として,乱流燃焼モデル構築の際に重要となる,火炎面密度を実験的に求め,これらが火炎伝播や圧力によってどのように変化するかについて検討を行った,その結果,火炎面密度は火炎の半径方向に分布しており,その最大値は火炎が伝播するにつれて小さくなることを明らかとした,これは,火炎が伝播するにつれて,ブラシ厚さが増大するためであると考えられる.また,同一の火炎半径において,火炎面密度の最大値は混合気初期圧力によってあまり変化しなかった,これは,混合気初期圧力が高くなるにつれて火炎面には細かい凹凸が形成され火炎面積が増大するものの,ブラシ厚さがわずかに増大するため,火炎面密度としてはあまり変化しなかったものと考えられる.

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