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Tetsushi Biwa

Section

Graduate School of Engineering

Job title

Professor

Degree

博士（工学）　名古屋大学

researchmap

https://researchmap.jp/read0210527

J-GLOBAL ID

200901035688104943

Research History 1

1999/04 - 2006/03

名古屋大学　助手

Education 3

Nagoya University　Graduate School, Division of Engineering　結晶材料工学専攻

- 1999/03/25
Nagoya University　Graduate School, Division of Engineering　結晶材料工学専攻

- 1995/03/25
Nagoya University　Faculty of Engineering　応用物理学科

- 1993/03/25

Committee Memberships 12

日本機械学会エンジンシステム部門「先進のスターリングサイクル機器研究会」(A-TS07-40)　委員

2003/04 - 2009/03
日本機械学会エンジンシステム部門「先進のスターリングサイクル機器研究会」(A-TS07-40)　委員

2003/04 - 2009/03
低温工学協会調査研究会「振動流エネルギー変換・輸送現象研究会」　主査

2005/04 - 2008/03
低温工学協会調査研究会「振動流エネルギー変換・輸送現象研究会」　主査

2005/04 - 2008/03
低温工学協会調査研究会「熱音響自励振動研究会」　運営委員

2002/04 - 2005/03
低温工学協会調査研究会「熱音響自励振動研究会」　運営委員

2002/04 - 2005/03
日本機械学会エンジンシステム部門「地球に優しいスターリングサイクルシステムの実用化研究会」(A-TS07-46)　委員

2009/04 -
日本機械学会エンジンシステム部門「地球に優しいスターリングサイクルシステムの実用化研究会」(A-TS07-46)　委員

2009/04 -
低温工学協会調査研究会「熱音響デバイス研究会」　主査

2008/04 -
低温工学協会調査研究会「熱音響デバイス研究会」　主査

2008/04 -
日本機械学会エンジンシステム部門スターリングサイクル委員会　委員

2005/04 -
日本機械学会エンジンシステム部門スターリングサイクル委員会　委員

2005/04 -

Show all ︎Show first 5

Professional Memberships 4

Acoustical Society of America
THE JAPAN SOCIETY OF MECHANICAL ENGINEERS
ACOUSTICAL SOCIETY OF JAPAN
低温工学協会

Research Interests 1

実験音響物理学

Research Areas 2

Natural sciences / Mathematical physics and basic theory / thermoacoustics
Manufacturing technology (mechanical, electrical/electronic, chemical engineering) / Thermal engineering / thermoacoustics

Awards 5

The Young Scientists' Prize, The Commendation for Science and Technology by the Minister of Education,Culture, Sports, Science and Technology

2009/04/06　文部科学省　熱音響現象に基づくエネルギー変換技術の研究
2007年度論文賞：（社）低温工学協会

2007/05/17　（社）低温工学協会　パルス管冷凍機と熱駆動熱音響冷凍機の効率
2006年度奨励賞：（社）低温工学協会

2006/05/16　（社）低温工学協会　熱音響エネルギー変換技術の実用化を目指した基礎研究
2004年度日本冷凍空調学会賞優秀講演賞

2005/05/16　（社）日本冷凍空調学会　熱音響スターリング冷凍機の開発
2001年度優良発表賞：（社）低温工学協会

2001/05/17　（社）低温工学協会　共鳴管につながれたループ状チューブにおける自励振動

Papers 114

Linear stability analysis of a combustor model with a delayed feedback tube Peer-reviewed

Yosuke Takabatake, Yuto Kasai, Eita Shoji, Tetsushi Biwa

Applied Energy　376　124249-124249　2024/12
Publisher: Elsevier BV
DOI： 10.1016/j.apenergy.2024.124249 　

ISSN： 0306-2619
Experimental study on liquid piston Stirling engine combined with self-rectifying turbine Peer-reviewed

Jidai Tomihira, Eita Shoji, Tetsushi Biwa, Prastowo Murti, Shinya Okuhara, Manabu Takao

The Journal of the Acoustical Society of America　156　(2)　792-799　2024/08/01
Publisher: Acoustical Society of America (ASA)
DOI： 10.1121/10.0028132 　

ISSN： 0001-4966

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A liquid piston Stirling engine is an external combustion engine that uses air and water under atmospheric pressure as its working fluids. Resulting from its uncomplicated design and the capacity to operate under relatively low temperature differentials of less than 100 °C, it has attracted considerable attention in recent years. This paper presents the fundamental characteristics of the liquid piston engine combined with a self-rectifying turbine for the advancement of thermal generators. When the turbine is installed in the water region rather than in the air region, it exhibits unidirectional rotation with a rotational speed directly proportional to the velocity amplitude of the reciprocating axial flow. Additionally, the acoustic impedance within the duct section containing the turbine is determined, demonstrating that the real part of impedance rises with increasing axial velocity, indicating a loss mechanism similar to the minor loss. Furthermore, the installation of the turbine results in a breakdown of symmetry in the engine oscillation mode. To maintain symmetry and improve system design, future developments must consider the installation of a turbine in each unit. These findings can pave the way to the design of liquid piston Stirling engines and their applications in thermal energy conversion.
Analysis of a standing wave thermoacoustic engine with multiple unit stages Peer-reviewed

Prastowo Murti, Ikhsan Setiawan, Jihan Zeinyuta Rosafira, Adhika Widyaparaga, Wijayanti Dwi Astuti, Tetsushi Biwa

International Journal of Renewable Energy Development　13　(4)　708-715　2024/05/15
Publisher: Center of Biomass and Renewable Energy Scientia Academy
DOI： 10.61435/ijred.2024.60098 　

ISSN： 2252-4940

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The thermoacoustic engine is an eco-friendly technology capable of harnessing solar and waste energy for electricity generation, in conjunction with a linear alternator, and can function as a heat pump. This engine type holds significant appeal due to its simplistic design, devoid of any mechanical moving components, comprising only a stack sandwiched between heat exchangers within a resonator. When the temperature gradient across the stack reaches the critical threshold (onset temperature), the working gas undergoes spontaneous oscillation. Typically, a high onset temperature is necessary to induce gas oscillation in a thermoacoustic engine due to viscous losses within the system. A method to lower the onset temperature by increasing the number of unit stages consisting of stacks and heat exchangers so that the engine can utilize low-grade thermal sources has been developed to overcome this challenge. However, this method has only been applied to traveling-wave thermoacoustic engines. Its application in standing-wave engines, which offer a more compact and straightforward structure, remains unexplored. This research aims to examine how the number of unit stages in a standing-wave thermoacoustic engine influences the onset temperature and acoustic field. The onset temperature is estimated using a fundamental hydrodynamics equation and the investigation of the acoustic field throughout the engine using DeltaEC software. Results showed that the strategic positioning of multiple unit stages is essential to achieve a low onset temperature. The minimum onset temperature, approximately 92°C, is obtained when three- or four-unit stages are installed. Additionally, increasing the number of unit stages does not affect the acoustic impedance and phase difference between pressure and velocity in the stack, while simultaneously enhancing both acoustic power output and thermal efficiency.
Time-resolved measurement of acoustic density fluctuations using a phase-shifting Mach-Zehnder interferometer Peer-reviewed

Eita Shoji, Anis Maddi, Guillaume Penelet, Tetsushi Biwa

The Journal of the Acoustical Society of America　155　(4)　2438-2444　2024/04/01
Publisher: Acoustical Society of America (ASA)
DOI： 10.1121/10.0025537 　

ISSN： 0001-4966

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Phase-shifting interferometry is one of the optical measurement techniques that improves accuracy and resolution by incorporating a controlled phase shift into conventional optical interferometry. In this study, a four-step phase-shifting interferometer is developed to measure the spatiotemporal distribution of acoustic density oscillations of the gas next to a rigid plate. The experimental apparatus consists of a polarizing Mach–Zehnder interferometer with a polarization camera capable of capturing four polarization directions in one shot image and it is used to measure the magnitude and the phase of density fluctuations through a duct of rectangular cross section connected to a loudspeaker. The results are compared with the well-established thermoacoustic theory describing the thermal coupling between acoustic oscillations and rigid boundaries, and the results show a very good agreement for various ratios of the (frequency-dependent) thermal boundary layer thickness to the plate spacing. This measurement technique could be advantageously employed to analyze more complex heat transfer processes involving the coupling of acoustic oscillations with rigid boundaries.
Analysis of multi-cylinder type liquid piston Stirling cooler Peer-reviewed

Prastowo Murti, Eita Shoji, Tetsushi Biwa

Applied Thermal Engineering　219　119403-119403　2023/01
Publisher: Elsevier BV
DOI： 10.1016/j.applthermaleng.2022.119403 　

ISSN： 1359-4311
Rotational dynamics of a looped-tube thermoacoustic engine with a flywheel Peer-reviewed

Takumaru Watanabe, Eita Shoji, Tetsushi Biwa, Guillaume Penelet

Physical Review Applied　18　044079　2022/10

DOI： 10.1103/PhysRevApplied.18.044079 　
Thermoacoustic modeling of Fluidyne engine with a gas-coupled water pumping line Peer-reviewed

T. Biwa, M. Prastowo, E. Shoji

The Journal of the Acoustical Society of America　152　(4)　2212-2219　2022/10
Publisher: Acoustical Society of America (ASA)
DOI： 10.1121/10.0014698 　

ISSN： 0001-4966

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A Fluidyne engine is a Stirling engine with liquid pistons that automatically start to oscillate when the engine's regenerator is differentially heated to a certain level. This study investigates the thermally induced oscillations of the working gas and liquid in the Fluidyne engine using the results of the thermoacoustic theory. Further, the water pump performance of the Fluidyne engine is evaluated when it is coupled to the pumping line. The theoretical formulation and calculation results were verified by experimental tests on the onset temperature ratio and pump performance.
Analysis of the linear oscillation dynamics of Fluidyne engines

M. Ito, P. Murti, S. Tsuboi, E. Shoji, T. Biwa

The Journal of the Acoustical Society of America　151　(2)　1133-1141　2022/02
Publisher: Acoustical Society of America (ASA)
DOI： 10.1121/10.0009571 　

ISSN： 0001-4966
Design guideline for multi-cylinder-type liquid-piston Stirling engine Peer-reviewed

Prastowo Murti, Akira Takizawa, Eita Shoji, Tetsushi Biwa

Applied Thermal Engineering　200　117635-117635　2022/01
Publisher: Elsevier BV
DOI： 10.1016/j.applthermaleng.2021.117635 　

ISSN： 1359-4311
Periodic acoustic pulse generation by mode locked thermoacoustic oscillator Peer-reviewed

Y. Hirayama, T. Biwa, R. Delage

The Journal of the Acoustical Society of America　150　(4)　2310-2315　2021/10
Publisher: Acoustical Society of America (ASA)
DOI： 10.1121/10.0006536 　

ISSN： 0001-4966
Study of a thermoacoustic-Stirling engine connected to a piston-crank-flywheel assembly Peer-reviewed

Guillaume Penelet, Takumaru Watanabe, Tetsushi Biwa

The Journal of the Acoustical Society of America　149　(3)　1674-1684　2021/03
Publisher: Acoustical Society of America (ASA)
DOI： 10.1121/10.0003685 　

ISSN： 0001-4966
Linear alternator for liquid piston thermoacoustic stirling engine

Prastowo Murti, Akira Takizawa, Tetsushi Biwa

"Advances in Acoustics, Noise and Vibration - 2021" Proceedings of the 27th International Congress on Sound and Vibration, ICSV 2021　2021
Publisher: Silesian University Press
Flywheel-based traveling-wave thermoacoustic engine Peer-reviewed

T. Biwa, T. Watanabe, G. Penelet

Applied Physics Letters　117　(24)　243902-243902　2020/12/14
Publisher: AIP Publishing
DOI： 10.1063/5.0022315 　

ISSN： 0003-6951

eISSN： 1077-3118
Suppression of Rijke tube oscillations by delay coupling Peer-reviewed

H. Hyodo, M. Iwasaki, T. Biwa

Journal of Applied Physics　128　(9)　094902-094902　2020/09/07
Publisher: AIP Publishing
DOI： 10.1063/5.0012105 　

ISSN： 0021-8979

eISSN： 1089-7550
Synchronization of thermoacoustic quasiperiodic oscillation by periodic external force Peer-reviewed

M. Sato, H. Hyodo, T. Biwa, R. Delage

Chaos: An Interdisciplinary Journal of Nonlinear Science　30　(6)　063130-063130　2020/06
Publisher: AIP Publishing
DOI： 10.1063/5.0004381 　

ISSN： 1054-1500

eISSN： 1089-7682
Suppression of liquid surface instability induced by finite-amplitude oscillation in liquid piston Stirling engine Peer-reviewed

P. Murti, H. Hyodo, T. Biwa

Journal of Applied Physics　127　(15)　154901-154901　2020/04/21
Publisher: AIP Publishing
DOI： 10.1063/5.0003921 　

ISSN： 0021-8979

eISSN： 1089-7550
熱音響自励振動系に生じる非線形現象 Invited Peer-reviewed

琵琶哲志

システム制御情報学会誌　63　(9)　383-389　2019/09
Observation of thermoacoustic chaotic oscillations in a looped tube Peer-reviewed

Rémi Delage, Yusuke Takayama, Hiroaki Hyodo, Tetsushi Biwa

Chaos: An Interdisciplinary Journal of Nonlinear Science　29　(9)　093108-093108　2019/09
Publisher: AIP Publishing
DOI： 10.1063/1.5066363 　

ISSN： 1054-1500

eISSN： 1089-7682
Amplitude death in coupled thermoacoustic oscillators with frequency detuning

Hiroaki Hyodo, Tetsushi Biwa

Proceedings of the International Congress on Acoustics　2019-　5627-5632　2019
Publisher: International Commission for Acoustics (ICA)
DOI： 10.18154/RWTH-CONV-239634 　

ISSN： 2415-1599 2226-7808
Direct measurements of steady heat transfer maintained by oscillating pipe flow in thermoacoustic system Peer-reviewed

T. Biwa, T. Kobayashi, H. Hyodo

Journal of Applied Physics　125　014903　2019/01
Stabilization of thermoacoustic oscillators by delay coupling Peer-reviewed

H. Hyodo, T. Biwa

Physical Review E.　2019
Experimental and numerical analysis of a liquid-piston Stirling engine with multiple unit sections Peer-reviewed

S. Tamura, H. Hyodo, T. Biwa

Japanese Journal of Applied Physics　2019
Bifurcation diagram of coupled thermoacoustic chaotic oscillators Peer-reviewed

R. Delage, Y. Takayama, T. Biwa

Chaos　28　(8)　083125-083125　2018/08
Publisher: AIP Publishing
DOI： 10.1063/1.5037371 　

ISSN： 1054-1500

eISSN： 1089-7682
Study on Suppression of Thermoacoustic Oscillations Invited Peer-reviewed

BIWA Tetsushi, Hyodo Hiroaki

60　(192)　93-98　2018/05
Derivation of coupling conditions of amplitude death in delay-coupled thermoacoustic oscillators

Hiroaki Hyodo, Tetsushi Biwa

Proceedings of Meetings on Acoustics　34　(1)　2018
Publisher: Acoustical Society of America
DOI： 10.1121/2.0000882 　

ISSN： 1939-800X
Phase-locking and suppression states observed in forced synchronization of thermoacoustic oscillator Peer-reviewed

Hiroaki Hyodo, Tetsushi Biwa

Journal of the Physical Society of Japan　87　(3)　034402　2018
Publisher: Physical Society of Japan
DOI： 10.7566/JPSJ.87.034402 　

ISSN： 1347-4073 0031-9015
Stability Analysis of Thermoacoustic Gas Oscillations through Temperature Ratio Dependence of the Complex Frequency Peer-reviewed

Hiroaki Hyodo, Keita Muraoka, Tetsushi Biwa

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN　86　(10)　104401-1-104401-6　2017/10

DOI： 10.7566/JPSJ.86.104401 　

ISSN： 0031-9015
A looped-tube traveling-wave engine with liquid pistons Peer-reviewed

H. Hyodo, S. Tamura, T. Biwa

JOURNAL OF APPLIED PHYSICS　122　(11)　114902　2017/09

DOI： 10.1063/1.4986409 　

ISSN： 0021-8979

eISSN： 1089-7550
On-off intermittency in coupled chaotic thermoacoustic oscillations Peer-reviewed

Remi Delage, Yusuke Takayama, Tetsushi Biwa

CHAOS　27　(4)　043111-1-043111-5　2017/04

DOI： 10.1063/1.4981910 　

ISSN： 1054-1500

eISSN： 1089-7682
Measurement of Heat Flow Transmitted through a Stacked-Screen Regenerator of Thermoacoustic Engine Peer-reviewed

Shu Han Hsu, Tetsushi Biwa

APPLIED SCIENCES-BASEL　7　(3)　303　2017/03

DOI： 10.3390/app7030303 　

ISSN： 2076-3417
Modeling of a stacked-screen regenerator in an oscillatory flow Peer-reviewed

Shu Han Hsu, Tetsushi Biwa

Japanese Journal of Applied Physics　56　(1)　017301　2017/01/01
Publisher: Japan Society of Applied Physics
DOI： 10.7567/JJAP.56.017301 　

ISSN： 1347-4065 0021-4922
Suppression of Spontaneous Gas Oscillations by Acoustic Self-Feedback Peer-reviewed

Tetsushi Biwa, Yoshiki Sawada, Hiroaki Hyodo, Soichiro Kato

PHYSICAL REVIEW APPLIED　6　(4)　044020　2016/10

DOI： 10.1103/PhysRevApplied.6.044020 　

ISSN： 2331-7019
Experimental Demonstration of a Thermoacoustic Diode Peer-reviewed

Tetsushi Biwa, Hiroki Nakamura, Hiroaki Hyodo

PHYSICAL REVIEW APPLIED　5　(6)　064012-1-064012-8　2016/06

DOI： 10.1103/PhysRevApplied.5.064012 　

ISSN： 2331-7019
Performance evaluation of heat exchangers for thermoacoustic devices Peer-reviewed

小清水孝夫, 琵琶哲志

Trans. Of the JSRAE　32　(4)　453-459　2015/11/30
Publisher: Japan Society of Refrigerating and Air Conditioning Engineers
DOI： 10.11322/tjsrae.15-35TA_OA 　

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Thermoacoustic theory has been widely used for design of thermoacoustic devices and understanding phenomena in the devices. However, performance in a heat exchanger for thermoacoustic devices has not yet been fully understood because thermoacoustic theory cannot be applied to the heat exchanger absorbing or radiating heat. In this study, numerical analysis without thermoacoustic theory has been performed to evaluate the performance of the heat exchanger for heat absorption or heat radiation. In this paper, the influence of operating frequency on performance of the heat exchanger is investigated by introducing a heat transfer coefficient as an index for evaluating the performance. It was found that the heat transfer coefficient indicates a bigger value with increase in operating frequency and this means that the performance of the heat exchanger is improved with higher operating frequency. It is also found that heat transfer to the wall is enhanced with increase in operating frequency because the range in the radial direction affecting the heat exchange becomes smaller with higher operating frequency and thereby a temperature gradient becomes larger.
Construction of acoustic engine with alternator Peer-reviewed

大竹翔太, 兵頭弘晃, 琵琶哲志

Trans. Of the JSRAE　32　(4)　477-483　2015/11/30
Publisher: Japan Society of Refrigerating and Air Conditioning Engineers
DOI： 10.11322/tjsrae.15-33TA_OA 　

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One can realize an acoustic heat engine, a heat engine with no or less moving parts, as an application of thermoacoustic spontaneous oscillations of a gas column. The acoustic heat engine has been so far based on natural mode of oscillation of the gas column confined in a tube. In this study, we aim at constructing an acoustic engine with a voice coil type alternator. The alternator part is considered to replace a branch resonator of the acoustic engine made of a looped tube and the branch resonator, and thereby achieves both the lower operating frequency and the shorter engine length. This paper reports the operating condition and the performance of the combined system consisting of the engine part and the alternator part.
Amplitude Death in Coupled Thermoacoustic Oscillators Peer-reviewed

Tetsushi Biwa, Satoshi Tozuka, Taichi Yazaki

PHYSICAL REVIEW APPLIED　3　(3)　2015/03

DOI： 10.1103/PhysRevApplied.3.034006 　

ISSN： 2331-7019
Evolution Equation of Subcritical Hopf Bifurcation in Thermoacoustic Oscillations Peer-reviewed

H. Hyodo, T. Biwa

RECENT DEVELOPMENTS IN NONLINEAR ACOUSTICS　1685　2015

DOI： 10.1063/1.4934433 　

ISSN： 0094-243X
EXPERIMENTAL INVESTIGATION OF STACKED-SCREEN REGENERATOR LOCATED IN A HIGH IMPEDANCE ACOUSTIC FIELD Peer-reviewed

Shu Han Hsu, Tetsushi Biwa

PROCEEDINGS OF THE 22ND INTERNATIONAL CONGRESS ON SOUND AND VIBRATION　2015
Observation of thermoacoustic shock waves in a resonance tube (L) Peer-reviewed

Tetsushi Biwa, Kazuya Sobata, Shota Otake, Taichi Yazaki

JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA　136　(3)　965-968　2014/09

DOI： 10.1121/1.4892782 　

ISSN： 0001-4966

eISSN： 1520-8524
Measurements of acoustic particle velocity in a coaxial duct and its application to a traveling-wave thermoacoustic heat engine Peer-reviewed

Jun Morii, Tetsushi Biwa, Taichi Yazaki

REVIEW OF SCIENTIFIC INSTRUMENTS　85　(9)　094902　2014/09

DOI： 10.1063/1.4893639 　

ISSN： 0034-6748

eISSN： 1089-7623
Forced synchronization of periodic oscillations in a gas column: Where is the power source? Peer-reviewed

Takamasa Yoshida, Taichi Yazaki, Yuki Ueda, Tetsushi Biwa

Journal of the Physical Society of Japan　82　(10)　103001　2013/10

DOI： 10.7566/JPSJ.82.103001 　

ISSN： 0031-9015 1347-4073
Experimental Determination of the Evolution Equation for Thermally Induced Acoustic Oscillations Peer-reviewed

Tetsushi Biwa, Fumitomo Shima, Taichi Yazaki

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN　82　(4)　043401　2013/04

DOI： 10.7566/JPSJ.82.043401 　

ISSN： 0031-9015
Synchronization of a thermoacoustic oscillator by an external sound source Peer-reviewed

G. Penelet, T. Biwa

American Journal of Physics　81　(4)　290-297　2013/03/18

DOI： 10.1119/1.4776189 　

ISSN： 0002-9505
Amplitude Dependence of Thermoacoustic Properties of Stacked Wire Meshes

OBAYASHI Atsushi, HSU Shu-Han, BIWA Tetsushi

TEION KOGAKU　47　(9)　562-567　2012/09/25
Publisher: CRYOGENICS AND SUPERCONDUCTIVITY SOCIETY OF JAPAN
DOI： 10.2221/jcsj.47.562 　

ISSN： 0389-2441

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We compare a regenerator comprised of stacked wire meshes with that made of a honeycomb ceramic catalyst by measuring the acoustic fields in a tube containing the regenerator and air working gas at atmospheric pressure. The flow resistance of the wire-mesh regenerator increases in proportion to the velocity amplitude, whereas that of the honeycomb regenerator remains constant. An empirical equation of the flow resistance is proposed for the wire-mesh regenerator using an acoustic Reynolds number and ωτ_ν (ω is the angular frequency of the acoustic waves and τ_νis the viscous relaxation time given using effective pore radius). The difference between these regenerators is also observed in the increased acoustic power achieved in the presence of axial temperature differences.
How to build a loaded thermoacoustic engine Peer-reviewed

Hiroki Hatori, Tetsushi Biwa, Taichi Yazaki

JOURNAL OF APPLIED PHYSICS　111　(7)　074905　2012/04

DOI： 10.1063/1.3700244 　

ISSN： 0021-8979

eISSN： 1089-7550
Measurements of Work Flux Density in a Pulse Tube Engine

YOSHIDA Takamasa, YAZAKI Taichi, HAMAGUCHI Kazuhiro, BIWA Tetsushi

TEION KOGAKU　47　(1)　52-57　2012/01/25
Publisher: CRYOGENICS AND SUPERCONDUCTIVITY SOCIETY OF JAPAN
DOI： 10.2221/jcsj.47.52 　

ISSN： 0389-2441

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A kind of heat engine called a pulse tube engine has been recently proposed. The engine consists of only a few parts: differentially heated stacked metal meshes in a cylinder and one piston, coupled to a flywheel through a narrow flow passage called orifice. We built the prototype engine and tested its working mechanism from the standpoint of a thermoacoustic framework. We measured the work flux density distribution over the cross-section of the pulse tube to identify the work source of the engine and elucidate the function of the parts used in the engine. This engine belongs to the standing-wave engine group and the work source resides not in the stacked metal meshes but in the pulse tube. It is demonstrated that the stacked metal meshes are installed to break the thermodynamic symmetry, and that the orifice plays the role of extracting a maximum power from the engine.
Thermoacoustic analysis of a pulse tube refrigerator Peer-reviewed

T. Biwa

26TH INTERNATIONAL CONFERENCE ON LOW TEMPERATURE PHYSICS (LT26), PTS 1-5　400　2012

DOI： 10.1088/1742-6596/400/5/052001 　

ISSN： 1742-6588
Acoustic Power Amplification by Multiple Regenerators Peer-reviewed

琵琶哲志, 高尾景

低温工学　47　(1)　42-46　2012/01
Publisher: CRYOGENICS AND SUPERCONDUCTIVITY SOCIETY OF JAPAN
DOI： 10.2221/jcsj.47.42 　

ISSN： 0389-2441

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This paper reports on acoustic power amplification by a differentially heated regenerator. It is shown that the amplification gain approaches the ideal gain determined by the temperature ratio, and that the efficiency of converting heat power into acoustic power is expected to reach 63% of the Carnot efficiency when the specific acoustic impedance in the regenerator is increased to ten times larger than that of the traveling wave in a free space. When the three regenerators are aligned in series, a total acoustic power gain of ten is achieved with a temperature ratio of 1.95, but the efficiency is reduced to 7%. In order to upgrade the efficiency of three-stage acoustic power amplification, a branch resonator is tested.
Combined Thermoacoustic Device Peer-reviewed

大林敦, 琵琶哲志

低温工学　47　(1)　24-30　2012/01
Publisher: CRYOGENICS AND SUPERCONDUCTIVITY SOCIETY OF JAPAN
DOI： 10.2221/jcsj.47.24 　

ISSN： 0389-2441

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In this work, we attempt to understand a thermoacoustic device by dividing it into subsystems and analyzing the acoustic admittance of these subsystems experimentally. It is shown that the temperature difference controls the real part of the admittance, whereas the frequency changes the imaginary part of it. The combined device consisting of these subsystems is found to start working at the temperature difference and the frequency when acoustic admittances of the subsystems agree with each other. On the basis of the result, we propose two new designs for a double-loop thermoacoustic Stirling cooler.
Observation of traveling thermoacoustic shock waves (L) Peer-reviewed

Tetsushi Biwa, Takuma Takahashi, Taichi Yazaki

JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA　130　(6)　3558-3561　2011/12

DOI： 10.1121/1.3658444 　

ISSN： 0001-4966
Acoustical power amplification and damping by temperature gradients Peer-reviewed

Tetsushi Biwa, Ryo Komatsu, Taichi Yazaki

JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA　129　(1)　132-137　2011/01

DOI： 10.1121/1.3518776 　

ISSN： 0001-4966
Low temperature differential thermoacoustic Stirling engine Peer-reviewed

Tetsushi Biwa, Daichi Hasegawa, Taichi Yazaki

APPLIED PHYSICS LETTERS　97　(3)　034102 1-034102 3　2010/07

DOI： 10.1063/1.3464554 　

ISSN： 0003-6951
Observation of energy cascade creating periodic shock waves in a resonator Peer-reviewed

Tetsushi Biwa, Taichi Yazaki

JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA　127　(3)　1189-1192　2010/03

DOI： 10.1121/1.3291029 　

ISSN： 0001-4966
Acoustic impedance measurements of pulse tube refrigerators Peer-reviewed

Takashi Iwase, Tetsushi Biwa, Taichi Yazaki

JOURNAL OF APPLIED PHYSICS　107　(3)　034903　2010/02

DOI： 10.1063/1.3296225 　

ISSN： 0021-8979
Acoustic impedance measurements of pulse tube refrigerators Peer-reviewed

Takashi Iwase, Tetsushi Biwa, Taichi Yazaki

Journal of Applied Physics　107　(3)　2010

DOI： 10.1063/1.3296225 　

ISSN： 0021-8979
Low temperature differential thermoacoustic Stirling engine Peer-reviewed

D. Hasegawa, T. Biwa

The 14th International Stirling Engine Coference, Nov. 16-18 (2009), Groningen, The Netherlans　CD-ROM　2009/11/16
Multistage thermoacoustic Stirling engine electric generator Peer-reviewed

K. Takao, T. Biwa

The 14th International Stirling Engine Coference, Nov. 16-18 (2009), Groningen, The Netherlans　CD-ROM　2009/11/16
Publisher:
Acoustic Field Measurement in a Thermoacoustic Stirling Engine Peer-reviewed

H. Hatori, T. Biwa

The 14th International Stirling Engine Coference, Nov. 16-18 (2009), Groningen, The Netherlans　CD-ROM　95-96　2009/11/16
Work flux density measurements in a pulse tube engine Peer-reviewed

T. Yoshida, T. Yazaki, H. Futaki, K. Hamaguchi, T. Biwa

APPLIED PHYSICS LETTERS　95　(4)　044101　2009/07

DOI： 10.1063/1.3187546 　

ISSN： 0003-6951
Oscillatory-flow based Energy Conversion and Heat Transport Phenomena and their Applications

BIWA Tetsushi, INOUE Tatsuo

TEION KOGAKU　43　(12)　508-508　2008/12/25
Publisher: CRYOGENICS AND SUPERCONDUCTIVITY SOCIETY OF JAPAN
DOI： 10.2221/jcsj.43.508 　

ISSN： 0389-2441
Beginner's Guide to Measurement Techniques in Thermoacoustic Systems Invited Peer-reviewed

Tetsushi BIWA

Journal of the Cryogenic Society of Japan　43　(12)　517-526　2008/12/25
Publisher: CRYOGENICS AND SUPERCONDUCTIVITY SOCIETY OF JAPAN
DOI： 10.2221/jcsj.43.517 　

ISSN： 0389-2441

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The fundamentals of thermoacoustics constitute understanding thermoacoustic phenomena, the proposal of new thermoacoustic devices, and the development of new experimental techniques. This paper describes a practical guide to measurements of important physical quantities in thermoacoustic systems to help beginners understand the basic techniques. The direct method, involving measurements of pressure and velocity oscillations, and the two-sensor method are introduced for the measurement of work flow. A method for the dynamic calibration of a thermocouple is also presented to make measurements of temperature fluctuation possible. Particular emphasis is given accurately determining the phasing between oscillatory quantities.
Double-loop Thermoacoustic Stirling Cooler I. Work Flow Measurements Peer-reviewed

Tetsushi BIWA

Journal of the Cryogenic Society of Japan　43　(12)　536-542　2008/12/25
Publisher: CRYOGENICS AND SUPERCONDUCTIVITY SOCIETY OF JAPAN
DOI： 10.2221/jcsj.43.536 　

ISSN： 0389-2441

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We built and tested a double-loop thermoacoustic Stirling cooler. The cooler consists of a prime-mover loop, a branch resonator and a cooler loop. Work flow measurements were conducted to evaluate the efficiency of the cooler. It was found that efficiency corresponding to 6.6% of the Carnot efficiency was expected for the prime-mover loop, whereas a Carnot efficiency of 11.5% was expected for the cooler loop. Measurement of heat rejected by cooling water showed that unwanted heat loss significantly lowered the efficiency in the prime-mover loop. When the effective input heat to the regenerator was used to estimate the efficiency, the efficiency was found to be 20.4% of the Carnot efficiency, comparable to that of mechanical Stirling engines.
Double-loop Thermoacoustic Stirling Cooler II. Measurements of Acoustic StreamingVelocity Peer-reviewed

Tetsushi BIWA

Journal of the Cryogenic Society of Japan　43　(12)　543-547　2008/12/25
Publisher: CRYOGENICS AND SUPERCONDUCTIVITY SOCIETY OF JAPAN
DOI： 10.2221/jcsj.43.543 　

ISSN： 0389-2441

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In thermoacoustic devices with a looped tube, it has been pointed out that acoustic streaming circulating the loop leads to unwanted heat loss. In this research,, we measured the acoustic streaming velocity in a double-loop thermoacoustic Stirling cooler, and show that the streaming circulating the loop accounts for a heat loss of 150 W when input heat to the prime-mover loop is 408 W. It is also shown that the installation of an elastic membrane effectively suppresses the heat loss and thereby increases the performance of the prime-mover loop and cooler loop.
Experimental verification of a two-sensor acoustic intensity measurement in lossy ducts Peer-reviewed

Tetsushi Biwa, Yusuke Tashiro, Hiroshi Nomura, Yuki Ueda, Taichi Yazaki

JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA　124　(3)　1584-1590　2008/09

DOI： 10.1121/1.2953311 　

ISSN： 0001-4966
How Does Stirling Engine Work? Peer-reviewed

Tetsushi BIWA, Yusuke TASHIRO, Taichi YAZAKI

Journal of Power and Energy Systems　2　(5)　1254-1260　2008/08
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jpes.2.1254 　

ISSN： 1881-3062

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In this paper the working mechanism of Stirling engine is studied from the standpoint of thermoacoustic framework. The work flux measurement is performed in a glass tube equipped with/without a regenerator-heat exchanger assembly. An atmospheric pressure air confined in the tube is periodically perturbed by two speakers at the same frequency (=48Hz) but out of phase. It is experimentally demonstrated that the phasing of two pistons in the Stirling engine (alpha arrangement type) plays the role in creating a steady work flux from the compression piston to the expansion piston, whereas a differentially heated regenerator in the engine operates as a power amplifier for the traveling wave propagating up the temperature gradient.
Observation of Thermoacoustic Energy Conversion Peer-reviewed

Yusuke TASHIRO, Tetsushi BIWA, Taichi YAZAKI

Journal of Power and Energy Systems　2　(5)　1261-1266　2008/08
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jpes.2.1261 　

ISSN： 1881-3062

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In order to understand thermoacoustic phenomena from a point of view of thermodynamics, oscillating pressure, velocity and temperature were measured in the tube having a temperature gradient. By converting the measured Eulerian quantities to the Lagrangian quantities associated with a given gas parcel, we determined the local energy conversion rate per unit volume and time. The obtained data demonstrate the validity of the thermodynamic approach to thermoacoustic phenomena.
Measurements of sound propagation in narrow tubes Peer-reviewed

T. Yazaki, Y. Tashiro, T. Biwa

PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES　463　(2087)　2855-2862　2007/09

DOI： 10.1098/rspa.2007.1897 　

ISSN： 1364-5021
Acoustic intensity measurement in a narrow duct by a two-sensor method Peer-reviewed

Tetsushi Biwa, Yusuke Tashiro, Hiroshi Nomura, Yuki Ueda, Taichi Yazaki

REVIEW OF SCIENTIFIC INSTRUMENTS　78　(8)　086110　2007/08

DOI： 10.1063/1.2768929 　

ISSN： 0034-6748
Determination of a response function of a thermocouple using a short acoustic pulse Peer-reviewed

Yusuke Tashiro, Tetsushi Biwa, Taichi Yazaki

JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA　121　(4)　1956-1959　2007/04

DOI： 10.1121/1.2535534 　

ISSN： 0001-4966
Measurements of acoustic streaming in a looped-tube thermoacoustic engine with a jet pump Peer-reviewed

Tetsushi Biwa, Yusuke Tashiro, Masahiro Ishigaki, Yuki Ueda, Taichi Yazaki

JOURNAL OF APPLIED PHYSICS　101　(6)　064914　2007/03

DOI： 10.1063/1.2713360 　

ISSN： 0021-8979
Measurement of acoustic output power in a traveling wave engine Peer-reviewed

M. Miwa, T. Sumi, T. Biwa, Y. Ueda, T. Yazaki

ULTRASONICS　44　E1527-E1529　2006/12

DOI： 10.1016/j.ultras.2006.08.010 　

ISSN： 0041-624X

eISSN： 1874-9968
Energy flow measurements in acoustic waves in a duct Peer-reviewed

Tetsushi Biwa

ULTRASONICS　44　E1523-E1526　2006/12

DOI： 10.1016/j.ultras.2006.08.001 　

ISSN： 0041-624X
パルス管冷凍機と熱駆動熱音響冷凍機の効率 Peer-reviewed

上田祐樹, 琵琶哲志

低温工学　41　(2)　73-80　2006/02

DOI： 10.2221/jcsj.41.73 　
Response compensation of a thermocouple using a short acoustic pulse

Yusuke Tashiro, Tetsushi Biwa, Taichi Yazaki

INNOVATIONS IN NONLINEAR ACOUSTICS　838　363-+　2006

ISSN： 0094-243X
Visualization of acoustic streaming in a looped tube thermoacoustic engine with a jet pump Invited

Tetsushi Biwa, M. Ishigaki, Y. Tashiro, Y. Ueda, T. Yazaki

INNOVATIONS IN NONLINEAR ACOUSTICS　838　395-+　2006

ISSN： 0094-243X
Calibration of a thermocouple for measurement of oscillating temperature Peer-reviewed

Y Tashiro, T Biwa, T Yazaki

REVIEW OF SCIENTIFIC INSTRUMENTS　76　(12)　124901-1-124901-5　2005/12

DOI： 10.1063/1.2140489 　

ISSN： 0034-6748
Measurement of acoustic energy flows in a duct Invited Peer-reviewed

T. Biwa

World Congress on Ultrasonics Merged with Ultrasonics International, Aug. 28-Sep. 1, 2005, Beijing, China　2005/08/29
Measurement of acoustic output power in a traveling wave engine Peer-reviewed

M. Miwa, T. Biwa

World Congress on Ultrasonics Merged with Ultrasonics International, Aug. 28-Sep. 1, 2005, Beijing, China.　2005/08/29
Measurement of the Q value of an acoustic resonator Peer-reviewed

T Biwa, Y Ueda, H Nomura, U Mizutani, T Yazaki

PHYSICAL REVIEW E　72　(2)　026601-1-026601-6　2005/08

DOI： 10.1103/PhysRevE.72.026601 　

ISSN： 1539-3755
Thermodynamic cycles executed in a looped-tube thermoacoustic engine Peer-reviewed

Y Ueda, T Biwa, U Mizutani, T Yazaki

JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA　117　(6)　3369-3372　2005/06

DOI： 10.1121/1.1904503 　

ISSN： 0001-4966
Experimental demonstration of thermoacoustic energy conversion in a resonator Peer-reviewed

T Biwa, Y Tashiro, U Mizutani, M Kozuka, T Yazaki

PHYSICAL REVIEW E　69　(6)　066304　2004/06

DOI： 10.1103/PhysRevE.69.066304 　

ISSN： 1539-3755
Optical measurement of acoustic streaming in a waveguide

T. Biwa, M. W. Thompson, A. A. Atchley

The 18th International Congress on Acoustics, April 4-9, 2004, Kyoto.　2004　480-481　2004/04/04
Publisher:

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Acoustic streaming is measured for sound wave in a cylindrical waveguide driven by an acoustic driver at each end. We have determined the Lagrangia average of the velocity in standing-, traveling- waves and mixed fields consisting of both traveling and standing waves, quantitatively using laser Doppler anemometer. In a traveling wave, a very slow steady flow opposite to the acoustic intensity was observed in the core region of the tube and in the same direction near the tube wall. Experimental data are compared with theoretical prediction.
Measurement of temperature oscillations in acoustic waves in a tube

Y. Tashiro, T. Biwa, T. Yazaki, U. Mizutani

The 18th International Congress on Acoustics, April 4-9, 2004, Kyoto.　2004/04/04
Experimental studies of a thermoacoustic stirling prime mover and its application to a cooler Invited Peer-reviewed

Y Ueda, T Biwa, U Mizutani, T Yazaki

JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA　115　(3)　1134-1141　2004/03

DOI： 10.1121/1.1649333 　

ISSN： 0001-4966
Experimental evaluation of performance of a thermoacoustic Stirling cooler

UEDA Yuki, BIWA Tetsushi, SUMI Takao, KUMAZAWA Katsuyoshi, TACHIBANA Kazushi, Yazaki Taichi, MIZUTANI Uichiro

The proceedings of the JSME annual meeting　2004　31-32　2004
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecjo.2004.3.0_31 　

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We built and tested a thermoacoustic Stirling cooler. This cooler is composed of a looped tube and resonator. The energy conversions through the Stirling cycle are achieved by acoustically oscillating fluid in two regenerators located in the looped tube. In one of the regenerators, axial heat flow is converted into acoustic power flow, and in the other, heat pump effects are induced by the generated acoustic power flow. The lowest temperature of-26℃ was obtained when input power was 850 W. This type of cooler works without any moving parts like pistons. Therefore the cooler is potentially a powerful tool for application to generate refrigeration.
Amplification of acoustic intensity using thermoacoustic energy conversions

BIWA Tetsushi, TASHIRO Yusuke, UEDA Yuki, KOZUKA Motoki, YAZAKI Taichi

The proceedings of the JSME annual meeting　2004　25-26　2004
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecjo.2004.3.0_25 　

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We demonstrate amplification and strong damping of the acoustic intensity in a resonator using thermoacoustic energy conversions. A regenerator is installed in the middle of the resonator, and a steep temperature gradient is made along it. A resonant acoustic waveis produced in the resonator by an acoustic driver at the end. We experimentally determined the acoustic intensity entering and leaving the regenerator. As a result, we obtained the thermoacoustic amplification in case of a positive temperature gradient, and damping in a negative one.The present experimental result would contribute to the development of new acoustic devices usingthermoacousticenergy conversions.
Experimental demonstration of thermoacoustic energy conversion in a resonator Peer-reviewed

Tetsushi Biwa, Yusuke Tashiro, Uichiro Mizutani, Motoki Kozuka, Taichi Yazaki

Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics　69　(6)　6　2004

DOI： 10.1103/PhysRevE.69.066304 　

ISSN： 1063-651X
熱音響現象を使った新しい音響デバイス Invited

Tetsushi Biwa

TED Newsletter　41　2-6　2003/11
Self-tuning mechanism in a looped tube thermoacoustic engine

Y. Ueda, T. Biwa, T. Yazaki, U. Mizutani

5th World congress on Ultrasonics, September 7-10, 2003, Paris, France.　2003/09/07
Experimental evaluation of Q-values in a resonance tube

T. Biwa, Y. Ueda, Y. Tashiro, T. Yazaki, U. Mizutani

5th World congress on Ultrasonics, September 7-10, 2003, Paris, France.　2003/09/07
Amplification of the acoustic power using thermoacoustic energy conversions

Y. Tashiro, Y. Ueda, M. Kozuka, T. Biwa, T. Yazaki, U. Mizutani

5th World congress on Ultrasonics, September 7-10, 2003, Paris, France.　2003/09/07
Thermoacoustic effect in a Gifford-McMahon refrigerator

T Biwa, S Sunahara, U Mizutani

PHYSICA B-CONDENSED MATTER　329　1608-1609　2003/05

DOI： 10.1016/S0921-4526(02)02423-7 　

ISSN： 0921-4526
Construction of a thermoacoustic stirling cooler

Y Ueda, T Biwa, T Yazaki, U Mizutani

PHYSICA B-CONDENSED MATTER　329　1600-1601　2003/05

DOI： 10.1016/S0921-4526(02)02310-4 　

ISSN： 0921-4526
Low-temperature specific heat of overdoped Bi2201 single crystals

H Ikuta, M Matsuura, T Biwa

PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS　388　361-362　2003/05

DOI： 10.1016/S0921-4534(02)02506-6 　

ISSN： 0921-4534
A traveling-wave thermoacoustic engine

UEDA Yuki, BIWA Tetsushi, Mizutani Uichiro

The proceedings of the JSME annual meeting　2003　249-250　2003
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecjo.2003.7.0_249 　

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We have built a thermoacoustic engine composed of a regenerator, two heat exchangers and a looped tube. When a temperature gradient is set up along the regenerator by the pair of the heat exchangers, an acoustic wave spontaneously generates. By using pressure sensors, we simultaneously measure the pressure oscillations of the acoustic wave at 15 points along the looped tube. As a result, we found that a traveling acoustic wave runs around the tube and trough the regenerator from its cold to hot ends.
Thermodynamical mode selection rule observed in thermoacoustic oscillations Peer-reviewed

T Biwa, Y Ueda, T Yazaki, U Mizutani

EUROPHYSICS LETTERS　60　(3)　363-368　2002/11

DOI： 10.1209/epl/i2002-00273-1 　

ISSN： 0295-5075
Thermoacoustic heat pumping effect in a Gifford-McMahon refrigerator Peer-reviewed

S Sunahara, T Biwa, U Mizutani

JOURNAL OF APPLIED PHYSICS　92　(10)　6334-6336　2002/11

DOI： 10.1063/1.1517730 　

ISSN： 0021-8979
Acoutic Field in a Thermoacousic Stirling Engine consisting of a looped tube and resonator Peer-reviewed

Y. Ueda, T. Biwa, T. Yazaki, U. Mizutani

Applied Physics Letters　81　(27)　5252-5254　2002

DOI： 10.1063/1.1533113 　
Thermoacoustic Effect and Its Application as a Cooler Invited

T. Biwa

Refrigeration　77　240-246　2002
A pistonless Stirling cooler Peer-reviewed

T Yazaki, T Biwa, A Tominaga

APPLIED PHYSICS LETTERS　80　(1)　157-159　2002/01

DOI： 10.1063/1.1431695 　

ISSN： 0003-6951
Metal-insulator transition in the amorphous CexSi100-x (4 <= x <= 83) heavy fermion system Peer-reviewed

T Biwa, M Yui, T Takeuchi, U Mizutani

MATERIALS TRANSACTIONS　42　(6)　939-950　2001/06

DOI： 10.2320/matertrans.42.939 　

ISSN： 1345-9678

eISSN： 1347-5320
Work flow measurements in a thermoacoustic engine Peer-reviewed

T Biwa, Y Ueda, T Yazaki, U Mizutani

CRYOGENICS　41　(5-6)　305-310　2001/05

DOI： 10.1016/S0011-2275(01)00078-9 　

ISSN： 0011-2275
Spontaneous gas oscillations in a looped tube engine connected to a resonator Peer-reviewed

T. Biwa

Cryogenic Engineering　36　(4)　189-192　2001
Publisher:
DOI： 10.2221/jcsj.36.189 　

ISSN： 0389-2441
Thermodynamical Mode Selection Rule in Thermoacoustic Gas Oscillations

T. Biwa, Y. Ueda, T. Yazaki, U. Mizutani

Proceedings of the First International Workshop on Thermoacoustics, The Netherlands　2001

DOI： 10.1209/epl/i2002-00273-1 　
Thermodynamical Mode Selection Rule in Spontaneous Gas Oscillations

T. Biwa, Y. Ueda, T. Yazaki, U. Mizutani

Proceedings of the 17th International Congress on Acoustics, Rome　2001
Thermoacoustic Stirlng engine and cooler

Y. Ueda, T. Biwa, T. Yazaki, U. Mizutani

Proceedings of the 17th International Congress on Acoustics, Rome　2001
Effect of the Addition of Al, Fe, and Pd on ErAg Regenerator Material Peer-reviewed

W. Yagi, H. Iwata, T. Biwa, Mizutani

Cryogenic Engineering　35　(3)　116-125　2000
Publisher: CRYOGENICS AND SUPERCONDUCTIVITY SOCIETY OF JAPAN
DOI： 10.2221/jcsj.35.116 　

ISSN： 0389-2441

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We have measured the low temperature specific heats for Er (Ag_1-xM_x) (M=Al, Pd and Fe, x≤0.2) alloys over the temperature range of 1.5-25K to explore efficient regenerator materials suitable at low temperatures around 10K. In particular, the peak height of the volumetric specific heat of Er (Ag_0.9Al_0.1) alloy has reached 1.2J/(Kcm³) at 16.5K, which is 1.5 times higher than that of the ErAg compound previously reported. Its large specific heat is attributed to the 4-fold degeneracy in the ground state of the Er 4f-levels. Moreover, we have revealed that the addition of third elements M=Pd and Fe to the ErAg compound could lower the peak position of the specific heat to about 10K. We conclude that a series of the ternary Er (Ag_1-xM_x) (M=Al, Pd and Fe, x≤0.2) alloys can serve as good regenerator materials in the temperature range below 17K.
Relationship between the Temperature-Dependent Specific Heat of Regenerator Materials and Performance of a Gifford-McMahon Refrigerator

T. Biwa, S. Sunahara, H. Ikuta, U. Mizutani

Proceeding of the Sixth Joint Japanese-Sino Seminar on Cryocooler and its Applications　2000
Optimization of the Phase Angle between Oscillating Pressure and Displacement in a Gifford-McMahon Refrigerator

S. Sunahara, T. Biwa, U. Mizutani

Proceeding of the Sixth Joint Japanese-Sino Seminar on Cryocooler and its Applications　2000
Evaluation of the refrigeration in the Gifford-McMahon-Cycle refrigerator based on the thermoacoustic theory Peer-reviewed

T Biwa, H Ikuta, U Mizutani

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS　38　(6A)　3763-3771　1999/06

DOI： 10.1143/JJAP.38.3763 　

ISSN： 0021-4922
26pYS-4 Low emperature specific heat measurements of Bi-HTSC Peer-reviewed

Shimada M, Matsuura M, Biwa T, Ikuta H, Mizutani U, Nakayama Y, Shimoyama J, Kishio K

Meeting Abstracts of the Physical Society of Japan　54　(0)　558-558　1999
Publisher: The Physical Society of Japan
DOI： 10.11316/jpsgaiyo.54.2.3.0_558_4 　

ISSN： 1342-8349
Evaluation of Cu and Pb particles with different sizes as regenerator materials in the Gifford-McMahon-cycle refrigerator Peer-reviewed

T Biwa, H Ikuta, U Mizutani

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS　37　(10)　5808-5814　1998/10

DOI： 10.1143/JJAP.37.5808 　

ISSN： 0021-4922
Experimental Studies of the Enthalpy and Entropy Flows through the Regenerator of the GM Refrigerator

T. Biwa, Y. Hoshino, H. Ikuta, Y. Ohashi, T. Inoue, U. Mizutani

Proceeding of the Fifth Japanese-Sino Joint Seminar on the Cryocooler and its Applications　1997
Evaluation of low-temperature specific heats and thermal conductivities of Er-Ag alloys as regenerator materials Peer-reviewed

T Biwa, W Yagi, U Mizutani

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS　35　(4A)　2244-2248　1996/04

DOI： 10.1143/JJAP.35.2244 　

ISSN： 0021-4922

Show all ︎Show first 5

Misc. 100

Investigation of the mechanism of superspreading of nanofluid droplet based on measurements of nano liquid film near the contact line

庄司衛太, 星野瑛, 齋藤大河, 琵琶哲志, 久保正樹, 塚田隆夫, 笘居高明, 阿尻雅文

日本伝熱シンポジウム講演論文集(CD-ROM)　60th　2023

ISSN： 1346-1532
ナノフルイド液滴蒸発時の動的濡れと堆積ナノ粒子層の光学測定

庄司衛太, 齋藤大河, 琵琶哲志, 久保正樹, 塚田隆夫, 笘居高明, 阿尻雅文

化学工学会年会研究発表講演要旨集(CD-ROM)　87th　2022
ナノフルイド液滴蒸発時の動的濡れと堆積ナノ粒子層の光学測定

庄司衛太, 齋藤大河, 琵琶哲志, 久保正樹, 塚田隆夫, 笘居高明, 阿尻雅文

化学工学会秋季大会研究発表講演要旨集(CD-ROM)　52nd　2021
A06 Development of a thermoacoustic electric generator

Otake Shota, HYODO Hiroaki, BIWA Tetsushi

The Symposium on Stirlling Cycle　2015　(18)　11-12　2015/12/04
Publisher: The Japan Society of Mechanical Engineers
ISSN： 0918-9238

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We have developed a thermoacoustic electric generator consisting of a looped tube thermoacoustic engine and a voice coil type generator in place of an acoustic resonator. On the basis of measurements of the acoustic impedances of the looped tube engine and the generator, we modified the electric generator to make their acoustic impedances to become the same as each other. The thermoacoustic electric generator thus constructed oscillates at the frequency much lower than that expected from the engine size.
C01 A looped tube Stirling engine having liquid pistons

UCHIYA Ryo, HYODO Hiroaki, BIWA Tetsushi

The Symposium on Stirlling Cycle　2014　(17)　57-58　2014/12/05
Publisher: The Japan Society of Mechanical Engineers
ISSN： 0918-9238

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West proposed a looped Stirling engine with a liquid-column which the shape of is U. After this proposal, Martini worked the engine with 4 U-tubes, Li worked it with 3U-tubes. However, it's not clear that they undergo Stirling cycle and how the number of U-tubes affects the design. In this paper, we show that the engine of this type undergoes Stirling cycle, and the effect of the number of the U-tubes. By calculating the acoustic impedance in the middle of the gas-column theoretically, the possibility is showed that the engine undergoes Stirling cycle. And the number of the U-tubes can be changed by adjusting the length of gas-column or liquid-column to approach an acoustic impedance.
次世代冷凍システム技術の探訪

松岡文雄, 遠藤明, 大宮司啓文, 琵琶哲志, 稲田孝明, 岡村哲至

冷凍　85　2014/09
B01 Designing and making of a thermoacoustic engine electric generator

TAKEDA Shohei, BIWA Tetsushi

The Symposium on Stirlling Cycle　2013　(16)　73-74　2013/11/29
Publisher: The Japan Society of Mechanical Engineers
ISSN： 0918-9238

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A thermoacoustic engine electric generator should generate some electrical power from supplied heat if the equivalent acoustic impedance of the electric generator coincides with the acoustic impedance of the thermoacoustic engine at a certain frequency. In order to build such a thermoacoustic device, we measure the mechanical impedance of a voice coil motor and design a thermoacoustic engine which has proper acoustic impedance by numerical calculation based on thermoacoustic theory.
B07 Heat Transfer Characteristics of a Heat Exchanger in Oscillatory Flows

KOSHIMIZU Takao, BIWA Tetsushi, TAKATA Yasuyuki

The Symposium on Stirlling Cycle　2013　(16)　85-86　2013/11/29
Publisher: The Japan Society of Mechanical Engineers
ISSN： 0918-9238

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Numerical simulation of heat and fluid flow has been performed to estimate the value of time-averaged heat transfer coefficient between the working gas and the wall in oscillatory flows. Transient two-dimensional equations of continuity, momentum and energy were solved utilizing a TVD scheme. A physical model of a simple circular tube was used for the numerical simulation. In this study, the value of heat transfer coefficient in a heat exchanger was clarified by analyzing the numerical results of the two-dimensional simulation.
Periodically-Arrayed Thermoacoustic Engines

MORII Jun, BIWA Tetsushi

The Symposium on Stirlling Cycle　15　53-56　2012/11/17
Publisher: The Japan Society of Mechanical Engineers
ISSN： 0918-9238

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We study a problem of acoustic wave propagation in a periodic field created by the array of thermoacoustic engines. Possibility of acoustic power amplification is examined through the eigenvalue and eigenvector of the transfer matrix related to the unit cell of the system.
C07 Systematic performance evaluation of a multistage thermoacoustic engine by forced oscillations

HATORI Hiroki, BIWA Tetsushi

The Symposium on Stirlling Cycle　2012　(15)　51-52　2012/11/16
Publisher: The Japan Society of Mechanical Engineers
ISSN： 0918-9238

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We masured a thermal efficiency of a multistage thmoacoustic engine by a forced oscillation method. In the forced oscillation method, we can arbitrarily change the operating frequcncy and the acoustic power, independently of the temperature difference. As a result of the experiment we found that the themal efficiency of the thermoacoustic engine unit reached 6.58% which is 21.4% of Carnot effaaiciency when the operating frequency was 35 Hz and a hot end temperature was 150 ℃.
F104 Experiments on thermoacoustic properties of stacked mech screens

HSU Shu-han, OBAYASHI Atsushi, BIWA Tetsushi

National Symposium on Power and Energy Systems　2012　(17)　183-184　2012/06/20
Publisher: The Japan Society of Mechanical Engineers

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An empirical equation is addressed for evaluating the oscillatory-flow resistance of regenerators consisting of stacked mesh screens. The empirical equation is expressed by a linear function of velocity amplitude and parameterized by acoustic Reynolds number Re_h and ωτ_v (ωis the angular frequency of acoustic wave, and τ_v is the viscous relaxation time given by effective pore radius). In the absence of axial temperature difference, the flow resistance of regenerator is determined from measurements of the acoustic field at ends of the regenerator. The measured resistance per unit length of the regenerator is compared to the prediction of the empirical equation. Through the experiments with air at atmospheric pressure, helium and argon gases with mean pressure of 0.45 MPa, the maximum deviation of the empirical equation is found to be 6 percent.
Amplitude dependence of power gain by temperature difference

OBAYASHI Atsushi, BIWA Tetsushi

The Symposium on Stirlling Cycle　14　67-70　2011/12/07
Publisher: The Japan Society of Mechanical Engineers
ISSN： 0918-9238

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Through measurements of acoustic power, we studied two types of regenerators experimentally; one is made of ceramic honeycomb catalyst and the other is comprised of stacked wire meshes. It is found that the thermoacoustic theory can explain acoustic power decrease and increase by the positive temperature difference for the ceramic honeycomb but not for the stacked wire meshes. We proposed an empirical equation of wire mesh resistance by using two dimensionless meters; acoustic Reynolds number and ωτ_v. The observed acoustic power increase is found to be the sum of square term and cubic term of velocity amplitude.
C10 Coaxial Thermoacoustic Device

MORII Jun, BIWA Tetsushi

The Symposium on Stirlling Cycle　2011　(14)　119-120　2011/12/07
Publisher: The Japan Society of Mechanical Engineers
ISSN： 0918-9238

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We build a thermoacoustic engine unit composed of a coaxial tube and a regenerator, and measure the acoustic field when the gas column is forced to oscillate at the frequency of 50 Hz. It is found that the engine unit is capable of producing acoustic power when a sufficiently high temperature difference is created along the regenerator. A compact thermoacoustic Stirling engine would be built if the coaxial tube is used instead of a looped tube.
C03 Forced oscillation method for analyzing a multistage thermoacoustic engine

HATORI Hiroki, BIWA Tetsushi

The Symposium on Stirlling Cycle　2011　(14)　43-44　2011/12/07
Publisher: The Japan Society of Mechanical Engineers
ISSN： 0918-9238

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We introduce a forced oscillation method for analyzing a thermoacoustic engine unit. In this method, the internal gas is forced to oscillate by an acoustic driver at the arbitral operating condition regarding the oscillating frequency and the temperature difference. In the experiment, we found the thermal efficiency of the multistage thermoacoustic engine unit reached 6.1 % of Carnot efficiency when the operating frequency was 40 Hz and the temperature difference was 130 K.
D03 Heat Transfer Coefficient in Oscillatory Flows

KOSHIMIZU Takao, BIWA Tetsushi, KOHNO Masamichi, TAKATA Yasuyuki

The Symposium on Stirlling Cycle　2011　(14)　65-66　2011/12/07
Publisher: The Japan Society of Mechanical Engineers
ISSN： 0918-9238

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Numerical simulation of heat and fluid flow has been performed to estimate the value of time-averaged heat transfer coefficient between the working gas and the wail in oscillatory flows. Transient two-dimensional equations of continuity, momentum and energy were solved utilizing a TVD scheme. A physical model of a simple circular tube was used for the numerical simulation. In this study, the value of heat transfer coefficient in a heat exchanger was clarified by analyzing the numerical results of the two-dimensional simulation.
B204 Acoustic field measurement of a coaxial thermoacoustic cooler

MORII Jun, BIWA Tetsushi

National Symposium on Power and Energy Systems　2011　(16)　267-268　2011/06/22
Publisher: The Japan Society of Mechanical Engineers

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A gas-filled looped pipe having a regenerator can operate as an efficient thermoacoustic cooler, when it is driven by an acoustic driver via a branch resonator. This is because the loop provides a feedback path for the acoustic work flow. In this work, we test a coaxial tube as another configuration of the thermoacoustic cooler. The acoustic field in the coaxial tube having the regenerator between the inner and the outer pipes is measured using a laser Doppler vecocimeter and small pressure transducers. The work flow is observed to circulate through regenerator, meaning the feedback of the work flow, when the operating frequency is sufficiently low.
International Cryogenic Engineering Conference 23 and International Cryogenic Materials Conference 2010 [ICEC23-ICMC2010]

45　(9)　424-427　2010/09/25

ISSN： 0389-2441
The Research Road of the Next Generation Refrigeration System Technologies

MATSUOKA Fumio, ENDO Akira, DAIGUJI Hirofumi, BIWA Tetsushi, INADA Takaaki, OKAMURA Tetsuji

85　(995)　756-762　2010/09/15
Publisher: 日本冷凍空調学会
ISSN： 0034-3714
E202 Heat-driven thermoacoustic Stirling cooler

BIWA Tetsushi, HASEGAWA Daichi

National Symposium on Power and Energy Systems　2010　(15)　423-424　2010/06/20
Publisher: The Japan Society of Mechanical Engineers

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In a heat-driven thermoacoustic Stirling cooler, lowering the hot end temperature necessary for the operation is of great importance. In this work, we increased a number of regenerators to five used in the engine loop of this type of cooler, and succeeded in lowering the temperature ratio significantly. Experimental results suggest that the cooling temperature of -4℃ is achievable with the hot end temperature of 200℃.
E206 Acoustic field control of a thermoacoustic engine

OBAYASHI Atsushi, BIWA Tetsushi

National Symposium on Power and Energy Systems　2010　(15)　431-432　2010/06/20
Publisher: The Japan Society of Mechanical Engineers

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In a double-loop thermoacoustic Stirling cooler, a branch resonator is used to transfer the acoustic power generated in an engine loop to a cooler loop. Through measurements of acoustic admittance, we show that the resonator works not only as a power transfer tube, but also as an admittance adjuster to connect two loops that have different admittances. Based on this observation, we apply the acoustic theory to realize the same function with a branch resonator having different internal radius. Experimental result shows that decreasing the resonator internal radius from 20 mm to 12 mm decreases the resonator length from 1.85 m to 0.81 m without changing the operating frequency of the cooler.
E205 Design of a combined thermoacoustic Stirling engine

HATORI Hiroki, BIWA Tetsushi

National Symposium on Power and Energy Systems　2010　(15)　429-430　2010/06/20
Publisher: The Japan Society of Mechanical Engineers

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To determine the best frequency for achieving a high efficiency in a looped tube thermoacoustic engine, we measured the acoustic intensity with forced oscillation. As a result, we found that the gain of the acoustic power amplification increased as the frequency was decreased. This indicates that we should choose an acoustic load in the way that the operating frequency becomes as low as possible when it is combined with this looped tube engine.
Prediction of critical temperature difference in thermoacoustic oscillations

SHIMA Fumitomo, BIWA Tetsushi

2010　251-251　2010
Publisher: 日本流体力学会

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We have located the acoustic power source for self-sustained oscillations in a thermoacoustic system through measurements of acoustic intensities at various temperature differences. The stack region with a positive temperature difference is found to produce the acoustic power necessary to compensate for energy dissipation in the regions outside the stack. Based on this observation, we propose a quality factor measurement to predict experimentally the critical temperature difference before the system reaches the onset of oscillation.
C05 Acoustic field measurement of a coaxial thermoacoustic cooler

MORII Jun, BIWA Tetsushi

The Symposium on Stirlling Cycle　49-50　2010
Publisher: The Japan Society of Mechanical Engineers
ISSN： 0918-9238

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A gas-filled looped pipe having a regenerator can operate as an efficient thermoacoustic cooler, when it is driven by an acoustic driver via a branch resonator. This is because the loop provides a feed-back pass of the acoustic work flow supplied from the driver. In this work, we test capability of a coaxial tube as a different configuration from the loop. The acoustic field in the coaxial tube having the regenerator between the inner and the output pipes is measured using a laser Doppler vecocimeter and a small pressure transducers. The work flow is observed to circulate through regenerator, meaning the feed back of the work flow.
C10 Control of acoustic field by a branch duct

OBAYASHI Atsushi, BIWA Tetsushi

The Symposium on Stirlling Cycle　2009　(12)　113-114　2009/11/06
Publisher: The Japan Society of Mechanical Engineers
ISSN： 0918-9238

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In this paper, we report a method to control acoustic field in a main pipe of a thermoacoustic engine by onnecting a branch duct. This method is based on the fact that the complex acoustic admittance in the main pipe discontinuously changes at the position where the branch duct is connected. It is demonstrated that the connection of the branch duct with a proper length at a right position turns the existing acoustic field in the main pipe to a pure traveling wave field without introducing the acoustic power loss flowing down the branch duct. This method would be applicable to various thermoacoustic devices such as a looped-tube traveling wave engine.
Critical onset temperature of spontaneous gas oscillations in thermoacoustic systems with multiple regenerators

Reports of Toyoda Physical and Chemical Research Institute.　(62)　209-213　2009/05
Publisher: 豊田理化学研究所
ISSN： 0372-039X
Shock wave observed in thermoacoustic gas oscillations

TAKAHASHI Takuma, BIWA Tetsushi

2009　179-179　2009
Publisher: 日本流体力学会

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This is the report paper in which the excitation of shock wave in a looped-tube thermoacoustic system is experimentally studied. It was observed that the acoustic gas oscillations induced by thermoacoustic instability became distorted and evolved into shock waves as the temperature ratio imposed on a stack was increased to 1.77. Measurements of work flow in the shock waves show that not only the fundamental but also the second mode are produced in the stack region. This indicates that thermoacoustic effects contribute to the formation of shock waves through thermal amplification of harmonic oscillations.
B220 Thermoacoustic Engine with Multiple Regenerators

HASEGAWA Daichi, BIWA Tetsushi

National Symposium on Power and Energy Systems　297-298　2009
Publisher: The Japan Society of Mechanical Engineers

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How much can we lower the onset temperature ratio (OTR) that is necessary for a thermoacoustic engine to start? We tried to answer this question by installing a secondary regenerator into a traveling wave engine consisting of a looped tube and a branch resonator. Factors governing the OTR were experimentally studied through measurements of the quality factor at various temperature ratios. It was found that the installation of the secondary regenerator at a suitable position drastically enhanced thermoacoustic effects while introducing a slight damping to the system. As a result, the OTR of the present thermoacoustic engine was decreased from 1.76 to 1.19, when the total number of regenerators was increased to 5.
Beginner's guide to Measurement Techniques in Thermoacoustic Systems

Tetsushi BIWA

Journal of the Cryogenic Society of Japan　43　(12)　517-526　2008/12
Publisher: Cryogenic Association of Japan
DOI： 10.2221/jcsj.43.517 　
D03 Comparison of the performance of regenerators in acoustical traveling-wave engine

KOMATSU Ryo, BIWA Tetsushi

The Symposium on Stirlling Cycle　2008　(11)　73-74　2008/11/05
Publisher: The Japan Society of Mechanical Engineers
ISSN： 0918-9238

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An acoustical traveling-wave engine was theoretically proposed by Ceperley [J. Acoust. Soc. Am., 66, 1508-1513(1979)]. In the regenerator with a positive temperature gradient, the gas exchanging heat isothermally with solid walls undergoes a thermodynamic cycle essentially similar to a Stirling cycle. As a result, acoustic waves through the regenerator are amplified. This idea showed a good starting point leading to developments of various thermoacoustic devices, but has not been verified yet by experiments. In this work, we conducted the experiments similar but with wider experimental parameters; temperature ratio (1 ≤< T_H/T_C < 2.3), frequency (3 < f < 200 Hz), and regenerator materials (0.3 < r_o, r_l < 0.8 mm). We show that a ceramic honeycomb functions better as a regenerator materials than a stack of stainless-steel screens.
C02 Direct Observation of Thermoacoustic Energy Conversion

HAYASHI Hiroyuki, BIWA Tetsushi

The Symposium on Stirlling Cycle　2008　(11)　77-78　2008/11/05
Publisher: The Japan Society of Mechanical Engineers
ISSN： 0918-9238

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In this work, we report thermodynamic cycle experienced by fluid parcels oscillating in a tube with a positive temperature gradient. Our experimental setup consists of a glass tube with a radius of 6.975 mm and a woofer speaker that is used to drive a gas column of atmospheric air filled in the tube at a frequency of 1.0 Hz. The non-dimensional parameter ωτ_α was below 10 in this experiment, which permits heat exchange between oscillating gas parcels and the tube wall. Lagrangian temperature and entropy associated with a given gas parcel were determined using the Eulerian pressure, velocity and temperature oscillations measured by experimental probes fixed in space. We show how the local energy conversion rate per unit time and volume changes with radial position, which verifies the thermodynamical approach to the understanding of thermoacoustic phenomena.
Measurement of acoustic impedance in a pulse tube refrigerator

IWASE Takashi, BIWA Tetsushi

The Symposium on Stirlling Cycle　11　81-84　2008/11/05
Publisher: The Japan Society of Mechanical Engineers
ISSN： 0918-9238

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Cooling temperature of a pulse tube refrigerator was dramatically improved by adding an orifice valve at the end of the pulse tube. However, there are few experimental results on how oscillatory flow changes upon opening the valve. In this work, we try to understand the gas dynamics in an orifice pulse tube refrigerator by measuring velocity and pressure oscillations. We used Laser Doppler Velocimeter (LDV) for the velocity and small pressure sensors for the pressure to determine the complex acoustic impedance near the cold end of the regenerator. When the phase of the acoustic impedance is the smallest, the lowest cooling temperature was obtained. With opening the orifice valve, a semicircular locus of the acoustic impedance was drawn on the complex plane, from which the roles of the components of the pulse tube refrigerator are discussed.
Thermoacoustic amplification and attenuation of sound waves traveling in a tube with temperature gradients

KOMATSU Ryo, BIWA Tetsushi

78　139-139　2008/05/26

ISSN： 0919-5998
Measurement of acoustic impedance in a pulse tube refrigerator

IWASE Takashi, BIWA Tetsushi

78　140-140　2008/05/26

ISSN： 0919-5998
Acoustic streaming measurements in a double-loop thermoacoustic Stirling cooler

BIWA Tetsushi

77　63-63　2007/11/20

ISSN： 0919-5998
Thermoacoustic approach to Stirling engines

BIWA Tetsushi, YAZAKI Taichi

77　64-64　2007/11/20

ISSN： 0919-5998
OS11-2 Double-loop thermoacoustic Stirling cooler

Biwa T.

National Symposium on Power and Energy Systems　2007　(12)　217-218　2007/06/13
Publisher: The Japan Society of Mechanical Engineers

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We built and tested a double-loop thermoacoustic Stirling cooler consisting of a prime-mover loop, a cooler loop and a branch resonator. This heat-driven thermoacoustic cooler makes it possible to generate low temperatures without any moving parts. The axial distribution of the acoustic power flow was measured to determine the efficiency of the thermoacoustic energy conversion.
Intensity measurement of shock waves in a gas-filled resonator

Biwa T., Tashiro Y., Yazaki T.

2007　218-218　2007
Publisher: 日本流体力学会

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We experimentally study shock formation in acoustic gas oscillations through measurements of the acoustic intensity. A gas column of atmospheric air in a cylindrical resonator was driven sinusoidally by an oscillating piston at the fundamental resonance frequency. The piston's Mach number was adjusted to be 1.8×10-4, large enough to cause a periodic shock wave in the resonator. Acoustic pressure and axial acoustic particle velocity of the gas column were measured using small pressure transducers and a laser Doppler velocimeter. We show the nonlinear interaction between the fundamental and the second harmonic from spatial distribution of the acoustic intensity associated with these modes.
C05 Direct observation of energy conversion in a regenerator

TASHIRO Yusuke, BIWA Tetsushi, YAZAKI Taichi

The Symposium on Stirlling Cycle　2006　(10)　43-44　2006/10/19
Publisher: The Japan Society of Mechanical Engineers
ISSN： 0918-9238

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In this paper, we report the direct observation of the energy conversion in a narrow tube having a temperature gradient. A gas parcel in the tube was driven by an oscillating piston at 1.00Hz to assure good thermal contact with the tube wall. We measured the oscillations of pressure and velocity in the tube to determine the acoustic intensity in the tube. We observed the amplification of the acoustic intensity in the region having a positive temperature gradient. We derived specific volume oscillation of the gas parcel from the measured pressure and temperature. The increase of the acoustic intensity per unit length was in good agreement with the enclosed area in the plot of pressure versus specific volume. This represents that the amplification of the acoustic intensity results from the thermodynamic cycles experienced by the gas parcel.
23pXG-3 Direct observation of acoustic power amplification in a narrow tube with temperature gradient

Tashiro Yusuke, Biwa Tetsushi, Yazaki Taichi

Meeting abstracts of the Physical Society of Japan　61　(2)　185-185　2006/08/18
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
23pXG-2 Intensity measurement in a periodic shock wave in an acoustic resonator

Biwa T., Tashiro Y., Yazaki T.

Meeting abstracts of the Physical Society of Japan　61　(2)　184-184　2006/08/18
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
28aXG-12 Power amplification of an acoustic pulse wave traveling in a narrow tube having a temperature gradient

Shinmei Masatoshi, Tashiro Yusuke, Biwa Tetsushi, Yazaki Taichi

Meeting abstracts of the Physical Society of Japan　61　(1)　281-281　2006/03/04
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
28aXG-11 Measurements of acoustic streaming in a traveling wave induced in a looped tube

Biwa Tetsushi, Ishigaki Masahiro, Yazaki Taichi

Meeting abstracts of the Physical Society of Japan　61　(1)　281-281　2006/03/04
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
28aXG-13 Acoustic-power amplification in resonator with temperature gradient

Tashiro Yusuke, Biwa Tetsushi, Yazaki Taichi

Meeting abstracts of the Physical Society of Japan　61　(1)　281-281　2006/03/04
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Cooling by sound : Understanding of thermo-acoustic refrigerator

YAZAKI Taichi, UEDA Yuki, BIWA Tetsushi

The Journal of the Acoustical Society of Japan　62　(2)　128-133　2006/02/01
Publisher: The Acoustical Society of Japan (ASJ)
ISSN： 0369-4232
AM06-16-017 Amplification of acoustic intensity of a pulse wave traveling through a duct with a temperature gradient

Biwa T., Tashiro Y., Shinmei M., Yazaki T.

2006　229-229　2006
Publisher: 日本流体力学会

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This paper reports the amplification of the acoustic intensity using acoustic pulse waves traveling in a long tube filled with atmospheric air. A regenerator with pore diameter 1.5mm was inserted in the tube, and the temperature gradient was externally imposed on it. Axial and temporal variation of acoustic pressure was measured by a series of pressure transducers. Because of the use of acoustic pulse waves, we could see the frequency dependence of the amplification rate of the acoustic intensity very easily. It is shown that the amplification rate was essentially determined by the ratio of the thermal boundary layer thickness to the pore radius of the regenerator.
AM06-16-015 Direct Observation of Thermoacoustic Energy Conversion in a tube

Tashiro Yusuke, Biwa Tetsushi, Yazaki Taichi

2006　227-227　2006
Publisher: 日本流体力学会

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In this paper, we report the direct observation of the thermoacoustic energy conversion in a narrow tube filled with atmospheric air. A gas in the tube was partly heated by an electrical heater, and driven by an oscillating piston at 1.00Hz. We measured the oscillations of pressure, velocity and temperature in the tube. We observed the amplification of the acoustic intensity in the region having a positive temperature gradient. The increase of the acoustic intensity per unit length was in good agreement with the enclosed area in the plot of pressure versus specific volume determined from the measured pressure and temperature. This represents that thermoacoustic energy conversion results from the thermodynamic cycles experienced by the gas.
Performance of a double-loop thermoacoustic Stirling cooler

MIWA Masaki, SUMI Takao, TASHIRO Yusuke, BIWA Tetsushi, UEDA Yuki, YAZAKI Taichi

73　293-293　2005/11/21

ISSN： 0919-5998
Performance of a thermoacoustic Stirling cooler filled with a pressurized gas

MIWA Masaki, SUMI Takao, KUMAZAWA Katsuyoshi, TASHIRO Yusuke, BIWA Tetsushi, UEDA Yuki, YAZAKI Taichi

72　99-99　2005/05/31

ISSN： 0919-5998
Measurement of temperature oscillation by using a thermocouple

TASHIRO Yusuke, BIWA Tetsushi, YAZAKI Taichi, MIZUTANI Uichiro

72　100-100　2005/05/31

ISSN： 0919-5998
D03 Measurement of temperature oscillation by using a thermocouple

TASHIRO Yusuke, BIWA Tetsushi, YAZAKI Taichi

The Symposium on Stirlling Cycle　63-64　2005
Publisher: The Japan Society of Mechanical Engineers
ISSN： 0918-9238

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Pressure-induced temperature oscillations are measured in a tube by using a thermocouple. The measured temperature oscillations are compared with those calculated from the simultaneously measured pressure oscillations. From the difference between them, the correction factor for the thermocouple is determined. We show the frequency and working gas dependences of the correction factor. We can obtain true temperature oscillation by using the thermocouple and the correction factor.
C04 Evaluation of the performance of a double-loop thermoacoustic Stirling cooler

MIWA Masaki, SUMI Takao, TASHIRO Yusuke, BIWA Tetsushi, UEDA Yuki, YAZAKI Taichi

The Symposium on Stirlling Cycle　79-80　2005
Publisher: The Japan Society of Mechanical Engineers
ISSN： 0918-9238

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We built and tested a double-loop thermoacoustic cooler consisting of an engine-loop, a branch resonator, and a cooler-loop. The cooling power of 6.4W was obtained at the cooling temperature of 0℃, when the input heat power of 416W was supplied to the engine-loop. We measured the acoustic power and found that the acoustic power emitted from the engine-loop was 12W, and that the acoustic power entering the cooler-loop was 6W. From the measured acoustic power, we obtained the efficiency of 0.029 in the engine-loop, and 1.1 in the cooler-loop. These correspond to 5.3% and 8.1% of the respective Carnot efficiencies.
AM05-16-017 Measurement of Temperature Oscillation in a tube using a pulse wave

Tashiro Yusuke, Biwa Tetsushi, Yazaki Taichi

2005　213-213　2005
Publisher: 日本流体力学会

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An experimental technique of measuring temperature oscillations in acoustic waves is presented. Differences in the amplitude and the phase of temperature oscillations between the measured one with a thermocouple and the analytical one derived from a laminar oscillating theory are described by two parameters Γ and θ, respectively. Using a short acoustic pulse, Γ and θ in the frequency below 50Hz are shown.
AM05-16-019 Evaluation of the performance of a thermoacoustic Stirling cooler

Biwa T., Miwa M., Tashiro Y., Sumi T., Kumazawa K., Yazaki T.

2005　215-215　2005
Publisher: 日本流体力学会

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We built a thermoacoustic Stirling cooler by connecting a prime-mover loop and a cooler loop with a resonator and tested its cooling performance. When the heat power supplied to the prime-mover loop exceeds some critical value, the prime-mover loop begins to emit the acoustic power flow, whereas the cooler loop pumps heat using the acoustic power flow running into the loop through the resonator. The axial distribution of the acoustic power flow was measured to determine the efficiency of the thermoacoustic energy conversion.
Thermoacoustic Cooler

BIWA Tetsushi

79　(925)　874-881　2004/11/15
Publisher: 日本冷凍空調学会
ISSN： 0034-3714
Visualization of steady flow in a looped tube thermoacoustic engine

ISHIGAKI Masahiro, BIWA Tetsushi, YAZAKI Taichi, MIZUTANI Uichiro

71　233-233　2004/11/01

ISSN： 0919-5998
Evaluation of work flow in narrow tubes by means of pressure measurements

NOMURA Hiroshi, UEDA Yuki, TASHIRO Yusuke, BIWA Tetsushi, YAZAKI Taichi, MIZUTANI Uichiro

71　232-232　2004/11/01

ISSN： 0919-5998
Acoustic power flow measurements in pressurized gas

MIWA Masaki, NOMURA Hiroshi, UEDA Yuki, TASHIRO Yusuke, BIWA Tetsushi, YAZAKI Taichi, MIZUTANI Uichiro

71　231-231　2004/11/01

ISSN： 0919-5998
Measurement of temperature oscillation by using pulse wave

TASHIRO Yusuke, BIWA Tetsushi, YAZAKI Taichi, MIZUTANI Uichiro

71　230-230　2004/11/01

ISSN： 0919-5998
熱音響冷凍

琵琶哲志

冷凍　79　(925)　50-57　2004/11
Publisher: 日本冷凍空調学会
Development of a thermoacoustic Stirling engine

BIWA Tetsushi

The Symposium on Stirlling Cycle　2004　(8)　97-98　2004/10/22
Publisher: The Japan Society of Mechanical Engineers
ISSN： 0918-9238

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Thermoacoustic prime movers and coolers constitutes a new class of heat engines, which use acoustic waves instead of moving parts such as pistons and valves. Their simple structure, and absence of moving parts offer a new way to understand heat engines. Thermoacoustic point of view, in which heat flow and work flow are used instead of heat and work, is introduced based on the experimental results on energy flows.
G242 Measurement of oscillating temperature of a sound wave in a tube

2004　478-479　2004
Publisher: 日本流体力学会

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In this experiment, we demonstrate the experimental technique to measure temperature oscillations of a sound wave in a tube. We directly insert a fine thermocouple into a glass tube and measure radial profile of temperature oscillations. By comparing experimental data with theoretical ones, we determine correction factors for the present thermocouple in the range from 0.5Hz to 18Hz. By using these correction factors, we can precisely and directly determine the temperature oscillations using a thermocouple.
Measurement of temperature fluctions in acoustic waves in a tube

TASHIRO Yusuke, BIWA Tetsushi, YAZAKI Taichi, MIZUTANI Uichiro

69　170-170　2003/12/03

ISSN： 0919-5998
New Acoustic Devices Based on Thermoacoustic Energy Conversion

琵琶哲志

TED Newsletter　(41)　2003/11
Publisher: 日本機械学会熱工学部門
New Acoustic Devices Based on Thermoacoustic Energy Conversion

Tetsushi Biwa

TED Newsletter on the WEB　(41)　2003/11
Publisher: Thermal Engineering Division, JSME
Experimental Demonstration of Thermoacoustic Energy Conversion

Tashiro Yusuke, Biwa Tetsushi, Ueda Yuki, Kozuka Motoki, Yazaki Taichi, Mizutani Uichiro

Meeting abstracts of the Physical Society of Japan　58　(2)　237-237　2003/08/15
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Measurements of Q-value in a resonance tube

Ueda Y., Biwa T., Yazaki T., Mizutani U.

Meeting abstracts of the Physical Society of Japan　58　(2)　250-250　2003/08/15
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
低コストで環境にやさしい熱音響エンジンを用いた音波冷凍機の開発

琵琶哲志

機械設計　47　(7)　39-42　2003/06
Publisher: 日刊工業新聞社
ISSN： 0387-1045
Experimental demonstration of thermoacoustic energy conversion

TASHIRO Yusuke, BIWA Tetsushi, UEDA Yuki, KOZUKA Motoki, YAZAKI Taichi, MIZUTANI Uichiro

68　168-168　2003/05/21

ISSN： 0919-5998
Mode selection rule observed in thermoacoustic oscillations

Biwa Tetsushi, Ueda Yuki, Yazaki Taichi, Mizutani Uichiro

Meeting abstracts of the Physical Society of Japan　58　(1)　290-290　2003/03/06
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Thermoacoustic cooler driven by spontaneous gas oscillations

UEDA Yuki, BIWA Tetsushi, Yazaki Taichi, Mizutani Uichiro

2003　129-131　2003
Publisher: 日本機械学会

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An efficient thermoacoustic Stirling prime mover based on traveling acoustic wave energy conversions has been developed. [S. Backhaus and G. W. Swift; Nature 399,355(1999)] We experimentally reveal the acoustic field spontaneously induced in the thermoacoustic prime mover through simultaneous measurements of velocity U and pressure P. The measured acoustic field allows us to construct a thermoacoustic cooler having no moving parts. This cooler reaches the lowest temperature of -25℃ without moving parts.
Stirling cooler driven by thermoacoustic oscillations

Ueda Y., Biwa T., Yazaki T., Mizutani U.

Meeting abstracts of the Physical Society of Japan　58　(1)　290-290　2003
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Acoustic field in a thermoacosutic engine having a looped tube and resonator

UEDA Yuki, BIWA Tetsushi, YAZAKI Taichi, MIZUTANI Uichiro

2003　298-299　2003
Publisher: 日本流体力学会

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We have constructed a thermoacoustic engine consisting of a looped tube and resonator. Through the thermoacoustic energy conversions executed in a regenerator, this engine generates an acoustic field whose maximum pressure amplitude reaches 7.8kPa, corresponding to 7.8% of mean pressure. The acoustic field induced in the engine is determined through the simultaneous measurements of pressure and velocity, and the visualization of the acoustic streaming.
Experimental Demonstration of Sound wave Amplification and Attenuation by Thermoacoustic phenomena

TASHIRO Yusuke, BIWA Tetsushi, UEDA Yuki, KOZUKA Motoki, YAZAKI Taichi, MIZUTANI Uichiro

2003　296-297　2003
Publisher: 日本流体力学会

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In 1979 Ceperley proposed a "pistonless Stirling Engine" using thermoacoustic energy conversion due to traveling waves However, he didn't show any amplification of acoustic intensity overwhelming the losses in a regenerator. He attributed this result to a low acoustic impedance in a regenerator. In this experiment, we demonstrate the thermoacoustic energy conversion by using a resonance tube. When the second mode is induced in resonance tube, a high acoustic impedance is made at the middle of resonance tube. Also, pressure and velocity oscillations oscillated in phase at the nodes and antinodes, as in traveling waves. By installing the regenerator at the velocity node formed in the middle of the resonator, we show an amplification and attenuation of acoustic intensity in the regenerator.
Thermoacoustic Stirling engine using a resonance tube

TASHIRO Yusuke, BIWA Tetsushi, UEDA Yuki, YAZAKI Taichi, MIZUTANI Uichiro

67　160-160　2002/10/30

ISSN： 0919-5998
Construction of a large-scale thermoacoustic Stirling cooler

SASAKI Tsutomu, TASHIRO Yusuke, UEDA Yuki, SUMI Takao, KUMAZAWA Katsuyoshi, BIWA Tetsushi, MIZUTANI Uichiro

67　159-159　2002/10/30

ISSN： 0919-5998
Energy conversion mechanism in a water Stirling engine

BIWA Tetsushi, UEDA Yuki, YAZAKI Taichi, MIZUTANI Uichiro

The Symposium on Stirlling Cycle　2002　(6)　115-116　2002/10/15
Publisher: The Japan Society of Mechanical Engineers
ISSN： 0918-9238

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In this work, we simultaneously measured the pressure and velocity oscillations in a U-tube of a water Stirling engine. We found that the energy conversion from heat flux to work flux is executed through the Stirling cycles and that the acoustic impedance responsible for the energy conversion is considerably higher than other thermoacoustic engines. We conclude a water Stirling engine can be a powerful device for applications such as a prime mover and a cooler having no mechanical parts.
Phase tuning mechanism in a thermoacoustic Stirling engine

UEDA Yuki, BIWA Tetsushi, YAZAKI Taichi, MIZUTANI Uichiro

The Symposium on Stirlling Cycle　2002　(6)　121-122　2002/10/15
Publisher: The Japan Society of Mechanical Engineers
ISSN： 0918-9238

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When a steep temperature gradient is imposed on a regenerator contained in a looped tube by using two heat exchangers, acoustic waves are spontaneously generated as a result of the thermoacoustic energy conversions through the Stirling cycle. While the energy conversion in a conventional Stirling engine is performed by the carefully tuned pistons, a thermoacoustic Stirling engine does not have any mechanical parts to tune the acoustic wave responsible for the energy conversion. Thus, it is of great importance to study how the thermoacoustic engines perform energy conversions without moving parts. In this experiment, we focused on the phase angle between the pressure and velocity oscillations of gas parcels in a looped tube thermoacoustic engine. We demonstrate that the phase angle changes corresponding to the energy conversion process within the regenerator.
Thermoacoustic Stirling Engine using a resonance tube

TASHIRO Yusuke, BIWA Tetsushi, UEDA Yuki, YAZAKI Taichi, MIZUTANI Uichiro

The Symposium on Stirlling Cycle　2002　(6)　131-132　2002/10/15
Publisher: The Japan Society of Mechanical Engineers
ISSN： 0918-9238

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A thermoacoustic Stirling Engine with a high efficiency needs both the traveling wave phase and high acoustic impedance. However, the acoustic impedance of a freely traveling plane wave is fixed at the ρδ, resulting in significant viscous energy losses due to high acoustic velocities. So we focus on a position in a resonance tube, where both a high acoustic impedance and a traveling wave phase are formed. We put a regenerator stacked with many screen meshes into this paticular position and externally imposed steep temperature gradients along the regenerator. We succeed in the amplification and attenuation of sound intensity depending on the sign of the temperature gradient.
Sound wave amplification and attenuation

TASHIRO Yusuke, BIWA Tetsushi, UEDA Yuki, YAZAKI Taichi, MIZUTANI Uichiro

66　128-128　2002/05/18

ISSN： 0919-5998
Thermoacoustic Effect and Its Application as a Cooler

BIWA Tetsushi

Refrigeration　77　(893)　240-246　2002
Publisher: 日本冷凍空調学会
Energy conversion mechanism in a water Stirling engine

BIWA Tetsushi, UEDA Yuki, YAZAKI T., MIZUTANI Uichiro

65　198-198　2001/11/23

ISSN： 0919-5998
Construction of a double-loop type thermoacoustic cooler

SUMI Takao, BIWA Tetsushi, UEDA Yuki, TASHIRO Yusuke, MIZUTANI Uichiro

65　273-273　2001/11/23

ISSN： 0919-5998
D10 Work Flow Measurement in a Thermoacoustic Stirling Engine

UEDA Yuki, BIWA Tetsushi, Mizutani Uichiro

The Symposium on Stirlling Cycle　2001　(5)　141-142　2001/10/25
Publisher: The Japan Society of Mechanical Engineers
ISSN： 0918-9238

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We measured simultaneously the pressure and the velocity of the oscillating gas to determine the work flow and the phase difference between the pressure and velocity in a thermoacoustic traveling wave engine. We revealed that heat flow was converted into work flow through the Stirling cycle in the present engine. Moreover, we could determine a position where only the traveling wave is formed. An installation of a second regenerator at this particular position led us to construct a thermoacoustic Stirling cooler with low viscous losses.
D04 Optimization of the cooling power in a GM refrigerator by adjusting the phase angle between pressure and displacement oscillations

SUNAHARA Shigeyuki, BIWA Tetsushi, MIZUTANI Uichiro

The Symposium on Stirlling Cycle　2001　(5)　123-124　2001/10/25
Publisher: The Japan Society of Mechanical Engineers
ISSN： 0918-9238

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In this paper, the heat exchange process between the working gas and the regenerator materials is examined in the second-stage GM refrigerator. The temperature dependence of the cooling power is measured as a function of the phase angle between pressure and displacement oscillations of the working gas. It is found that the optimum phase angle maximizing the cooling power at a given temperature dramatically increases with decreasing temperature particular below 20 K. This behavior represents that the importance of the phase angle in order to increase the cooling power in the low temperature region.
Energy Conversion in Thermoacoustic Stirling Engines

BIWA Tetsushi, UEDA Yuki, MIZUTANI Uichiro

64　29-29　2001/05/16

ISSN： 0919-5998
A Thermoacoustic Strling Cooler

UEDA Yuki, BIWA Tetsushi, MIZUTANI Uichiro

64　30-30　2001/05/16

ISSN： 0919-5998
Optimization of the cooling power in a GM refrigerator by adjusting the phase angle between pressure and displacement oscillations

SUNAHARA Shigeyuki, BIWA Tetsushi, IKUTA Hiroshi, MIZUTANI Uichiro

64　31-31　2001/05/16

ISSN： 0919-5998
Low Temperature Specific Heat of Bi2201 Single Crystals in the Overdoped Region

Ikuta H., Matsuura M., Biwa T., Mizutani U.

Meeting abstracts of the Physical Society of Japan　56　(1)　579-579　2001/03/09
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Carrier density dependence of low temperature specific heat in Bi2201 single crystals

Matsuura M., Biwa T., Ikuta H., Mizutani U.

Meeting abstracts of the Physical Society of Japan　55　(2)　561-561　2000/09/10
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Topology of the Fermi surface and Band Structure near the Fermi level in the Pb-doped Bi_2Sr_2CuO_<6+δ> superconductor

Takeuchi T., Yokoya T., Matsuura M., Kondo T., Biwa T., Shin S., Ikuta H., Mizutani U.

Meeting abstracts of the Physical Society of Japan　55　(2)　529-529　2000/09/10
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
Spontaneous gas osicillations in a looped tube connected to a resonator

BIWA Tetsushi, IKUTA Hiroshi, MIZUTANI Uichiro

62　47-47　2000/05/29

ISSN： 0919-5998
Optimization of the cooling power of a GM refrigerator by adjusting a phase angle between oscillations in pressure and displacement

SUNAHARA Shigeyuki, BIWA Tetsushi, IKUTA Hiroshi, MIZUTANI Uichiro

62　51-51　2000/05/29

ISSN： 0919-5998
26pYQ-2 Magnetic properties and electoronic transport across the metal-insulator transition of amorphous Ce_xSi_<100-x>(4≤X≤63)alloy

Yui M, Rogatchev A, Biwa T, Takeda T, Ikuta H, Mizutani U

Meeting abstracts of the Physical Society of Japan　54　(2)　406-406　1999/09/03
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
25aYT-12 Magnetoresistance of (RE<Sr)_2NiO_4 single crystals

Ikuta H, Morika Y, Nozaki H, Biwa T, Nizutani U

Meeting abstracts of the Physical Society of Japan　54　(2)　504-504　1999/09/03
Publisher: The Physical Society of Japan (JPS)
ISSN： 1342-8349
熱音響理論に基づくGM冷凍機の冷凍能力の評価

日本応用物理学会誌　38　(6A)　3763-3771　1999
Cooling performance of Gifford-McMahon cycle cryocooler

BIWA Tetsushi, HOSHINO Yoshiki, IKUTA Hiroshi, MIZUTANI Uichiro

58　54-54　1998/05/20

ISSN： 0919-5998
GM式冷凍機の蓄冷材としての銅と鉛の表価

日本応用物理学会誌　37　10　1998
Er-Ag合金を使用したGM冷凍器の特性

琵琶哲志, 星野善樹, 水谷宇一郎

低温工学・超電導学会講演概要集 = Meetings of Cryogenics and Superconductivity　56　15-15　1997/05/14

ISSN： 0919-5998
Ce_<1-x>Pr_xAgの低温比熱特性

岩田英樹, 琵琶哲志, 星野善樹, 水谷宇一郎

低温工学・超電導学会講演概要集 = Meetings of Cryogenics and Superconductivity　56　17-17　1997/05/14

ISSN： 0919-5998
Evaluation of Low-Temperature specific Heats and Thermal Conductivities of Er-Ag Alloys as Regenerator Materials

BIWA Tetsushi, MIZUTANI Uichiro

31　(4)　190-196　1996/04/25

ISSN： 0389-2441

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Books and Other Publications 2

熱音響デバイス（音響テクノロジーシリーズ21）

琵琶哲志

コロナ社　2018/07
エネルギーの貯蔵・輸送

Tetsushi BIWA

エヌティーエス　2006/06/05

ISBN: 9784860431570

Presentations 95

熱音響はおもしろい〜その歴史と最近の話題〜

日本音響学会2016年春季研究発表会　2016/03/09
熱音響自励振動を用いた相互同期の観察

新海格, 兵頭弘晃

日本音響学会2016年春季研究発表会　2016/03/09
結合熱音響カオスシステムにおけるオンオフ間欠性

高山祐介, 兵頭弘晃, Delage Remi

日本音響学会2016年春季研究発表会　2016/03/09
複素周波数を用いた熱音響系における安定曲線の評価

村岡敬太, 兵頭弘晃

日本音響学会2016年春季研究発表会　2016/03/09
Understanding of thermoacoustic phenomena and their applications International-presentation

3rd Regional conference on energy engineering & 7th International conference of thermofluids,　2015/11/19
チューブを用いた遅れフィードバックによる燃焼振動抑制

澤田欣己, 兵頭弘晃, 加藤壮一郎

日本流体力学会年会2015　2015/09/26
熱音響自励振動系における高次の強制同期の観察

谷崎勇介, 兵頭弘晃

日本流体力学会年会2015　2015/09/26
温度勾配を利用した音響ダイオード

中村啓樹, 兵頭弘晃

日本音響学会2015年秋季研究発表会　2015/09/16
液体ピストンを持つループ型熱音響スターリングエンジン

打屋瞭, 兵頭弘晃

日本音響学会2015年秋季研究発表会　2015/09/16
Suppression of self-excited oscillations in coupled thermoacoustic oscillators International-presentation

International Symposium on Nonlinear Acoustics　2015/06/29
エンタルピー流計測により振動流場の熱交換の観測

兵頭弘晃, 河村憲一

第52回日本伝熱シンポジウム　2015/06/03
音の熱機関〜熱音響現象の理解と応用〜

日本伝熱学会東北支部講演会　2015/05/09
液体ピストンを持つループ型スターリングエンジン

打屋瞭, 兵頭弘晃

日本機械学会第17回スターリングサイクルシンポジウム　2014/12/06
液柱と気柱からなるループ管型進行波音波エンジンの設計

打屋瞭, 兵頭弘晃

第2回応用熱音響研究会　2014/09/23
熱音響自励振動系における強制同期の観察

谷崎勇介, 兵頭弘晃

第2回応用熱音響研究会　2014/09/23
光計測による管内音場計測

芳西岳, 兵頭弘晃

日本流体力学会年会2014　2014/09/15
Suppression of self-excited oscillations in a coupled thermoacoustic systems International-presentation

10th European Fluid Mechanics Conference　2014/09/14
管内振動流場のエンタルピー流計測

河村憲一, 兵頭弘晃

日本音響学会2014年秋季研究発表会　2014/09/03
熱音響自励振動系で観測された強制同期

谷崎勇介, 兵頭弘晃

日本音響学会2014年秋季研究発表会　2014/09/03
熱音響エンジン発電機の設計と製作

竹田章平

第１６回スターリングサイクルシンポジウム　2013/11/30
結合熱音響振動子系における熱音響自励振動の抑制

戸塚智史

日本音響学会2013年秋季研究発表会　2013/09/25
熱音響自励振動におけるカオス同期

蕎麦田和也

日本音響学会2013年秋季研究発表会　2013/09/25
管内音波のエンタルピー流計測

河村憲一

平成25年度第二回応用熱音響研究会　2013/09/20
積層ワイヤメッシュの等価流路半径

許書涵

平成25年度第二回応用熱音響研究会　2013/09/20
温度勾配のある共鳴管を周期的に配列した気柱音波の分散関係

大澤典明

日本流体力学会年会2013　2013/09/12
熱音響自励振動におけるカオス同期

蕎麦田和也

日本流体力学会年会2013　2013/09/12
エンタルピー流計測による振動流場の熱伝達の観測

河村憲一

第50回伝熱シンポジウム　2013/05/29
Understanding of thermoacoustic phenomena and their applications International-presentation

The 19th International Symposium on Nonlinear Acoustics　2012/05/21
Thermoacoustic analysis of pulse tube refrigerators International-presentation

26th International Conference on Low Temperature Physics　2011/08/10
熱音響現象の理解と応用

第6回固体イオニクスセミナー　2010/09/20
熱音響現象－現象理解のポイント－

日本音響学会2010年秋季研究発表会　2010/09/14
合成熱音響デバイス

大林敦

日本音響学会2010年秋季研究発表会　2010/09/14
Q値計測による熱音響自励振動の臨界点の予測

島史知

日本流体力学会年会2010　2010/09/09
合成熱音響デバイス

大林敦

第９回熱音響デバイス研究会　2010/07/10
熱駆動型熱音響スターリングクーラー

長谷川大地

第15回動力・エネルギー技術シンポジウム　2010/06/22
合成熱音響スターリングエンジンの設計指針

羽鳥宏樹

第15回動力・エネルギー技術シンポジウム　2010/06/22
熱音響エンジンの音場調整

大林敦

第15回動力・エネルギー技術シンポジウム　2010/06/22
熱音響エネルギー変換の観測

谷口寛樹

第８回熱音響デバイス研究会　2010/03/27
ISEC2009会議報告

第７回熱音響デバイス研究会　2009/12/19
Low temperature differential thermoacoustic Stirling engine International-presentation

D. Hasegawa

The 14th International Stirling Engine Coference　2009/11/16
Multistage thermoacoustic Stirling engine electric generator International-presentation

K. Takao

The 14th International Stirling Engine Coference　2009/11/16
Acoustic Field Measurement in a Thermoacoustic Stirling Engine International-presentation

H. Hatori

The 14th International Stirling Engine Coference　2009/11/16
Acoustic impedance measurements in pulse-tube refrigerators International-presentation

The 14th International Stirling Engine Coference　2009/11/16
熱音響スターリングエンジンにおける音場の計測

羽鳥宏樹

第12回スターリングサイクルシンポジウム　2009/11/06
多段熱音響スターリングエンジン発電機

高尾景

第12回スターリングサイクルシンポジウム　2009/11/06
枝管による音場の調整

大林敦

第12回スターリングサイクルシンポジウム　2009/11/06
熱音響自励振動衝撃波

高橋琢磨

第６回熱音響デバイス研究会　2009/10/10
機械系を接続した熱音響エンジンの性能予測

羽鳥宏樹

第６回熱音響デバイス研究会　2009/10/10
熱音響現象の測定技術

日本音響学会2009年秋季研究発表会　2009/09/15
熱音響自励振動衝撃波

高橋琢磨

日本流体力学会年会2009　2009/09/03
平成21年度文部科学大臣表彰若手科学者賞受賞記念講演「最近の研究から（可動部品を備えた熱音響系の実験）」

第５回熱音響デバイス研究会　2009/07/04
多段熱音響スターリングエンジン発電機

高尾景

第14回動力・エネルギー技術シンポジウム　2009/06/30
複数の蓄熱器を持つ熱音響エンジン

長谷川大地

第14回動力・エネルギー技術シンポジウム　2009/06/30

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フェロー賞受賞
ダブルインレット型パルス管冷凍機の音響インピーダンス

岩瀬貴志

2009年度低温工学・超電導学会　2009/05/13
低温度差熱音響スターリングエンジン

長谷川大地

2009年度低温工学・超電導学会　2009/05/13
低温度差熱音響スターリングエンジン

長谷川大地

第４回熱音響デバイス研究会　2009/03/28
パルス管冷凍機の音響インピーダンス計測

岩瀬貴志

第４回熱音響デバイス研究会　2009/03/28
進行波音波エンジンにおける蓄熱器の性能比較

小松遼

第11回スターリングサイクルシンポジウム　2008/11/05

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ベストプレゼンテーション賞受賞
熱音響エネルギー変換の直接観測

林寛之

第11回スターリングサイクルシンポジウム　2008/11/05
パルス管冷凍機における音響インピーダンスの計測

岩瀬貴志

第11回スターリングサイクルシンポジウム　2008/11/05
Intensity measurement of a periodic shock wave in a resonator International-presentation

Acoustics 08　2008/06/29
温度勾配による管内進行波音波の増幅と減衰

小松遼

第78回2008年度春季低温工学・超電導学会　2008/05/26
パルス管冷凍機における音響インピーダンス計測

岩瀬貴志

第78回2008年度春季低温工学・超電導学会　2008/05/26
温度勾配による管内進行波音波の増幅と減衰

小松遼

第４回振動流エネルギー変換・輸送現象研究会　2008/03/15
パルス管冷凍機における流体ダイナミクスの光計測

岩瀬貴志

第４回振動流エネルギー変換・輸送現象研究会　2008/03/15
Simulation-based response analysis of porous and non-porous infrasonic arrays

Timothy M. Marston

154th Meeting: Acoustical Society of America　2007/11/28
ダブルループ型熱音響スターリング冷凍機内の音響流計測

低温工学・超電導学会　2007/11/20
Intensity measurement of a periodic sock wave in a resonator International-presentation

T. Yazaki

19th International Congress on Acoustics　2007/09/02
気柱共鳴管内の衝撃波音波における音響強度測定

田代雄亮, 矢崎太一

日本流体力学会　2007/08/08
ダブルループ型熱音響スターリング冷凍機

三輪正樹, 田代雄亮, 鷲見高雄, 熊澤克芳, 矢崎太一

第12回動力エネルギーシンポジウム　2007/06/15
熱音響現象の基礎と応用

流体科学セミナー　2007/05/19
Direct observation of the thermoacoustic energy conversion in a tube International-presentation

Y. Tashiro, T. Yazaki

International Congress on Ultrasonics　2007/04/09
Amplification of acoustic intensity of a pulse wave propagating through a tube having a temperature gradient International-presentation

Y. Tashiro, M. Shinmei, T. Yazaki

Fourth Joint Meeting: ASA and ASJ　2006/11/28
Direct observation of thermoacoustic energy conversion International-presentation

Y. Tashiro, T. Yazaki

Fourth Joint Meeting: ASA and ASJ　2006/11/28
蓄熱器内のエネルギー変換の直接観測

田代雄亮, 琵琶哲志, 矢崎太一

第10回スターリングサイクルシンポジウム　2006/10/20
管内での熱音響エネルギー変換の直接観測

田代雄亮, 琵琶哲志, 矢崎太一

日本流体力学会年会2006　2006/09/15
温度勾配を持つ流路内を伝播する管内パルス音波の音響強度増幅

琵琶哲志, 田代雄亮, 新名雅俊, 矢崎太一

日本流体力学会年会2006　2006/09/15
Measurement of energy flows in acoustic waves International-presentation

World Congress on Ultrasonics merged with Ultrasonics International　2005/08/29
Measurement of acoustic output power in a traveling wave engine International-presentation

M. Miwa, T. Sumi, Y. Ueda, T. Yazaki

World Congress on Ultrasonics merged with Ultrasonics International　2005/08/29
Visualization of acoustic streaming in a looped tube thermoacoustic engine with a jet pump International-presentation

M. Ishigaki, Y. Tashiro, Y. Ueda, T. Yazaki

17th International Symposium on Nonlinear Acoustics　2005/07/18
Response compensation of a thermocouple using a short acoustic pulse International-presentation

Y. Tashiro, T. Biwa, T. Yazaki, M. Uichiro

17th International Symposium on Nonlinear Acoustics　2005/07/18
Optical measurement of acoustic streaming in a waveguide International-presentation

M. W. Thompson, A. A. Atchley

The 18th International Congress on Acoustics　2004/04/04
Measurement of temperature oscillations in acoustic waves in a tube International-presentation

Y. Tashiro, T. Yazaki, U. Mizutani

The 18th International Congress on Acoustics　2004/04/04
Self-tuning mechanism in a looped tube thermoacoustic engine International-presentation

Y. Ueda, T. Yazaki, U. Mizutani

5th World congress on Ultrasonics　2003/09/07
Experimental evaluation of Q-values in a resonance tube International-presentation

Y. Ueda, Y. Tashiro, T. Yazaki, U. Mizutani

5th World congress on Ultrasonics　2003/09/07
Amplification of the acoustic power using thermoacoustic energy conversions International-presentation

Y. Tashiro, Y. Ueda, M. Kozuka, T. Yazaki, U. Mizutani

5th World congress on Ultrasonics　2003/09/07
Thermoacoustic effect in a Gifford-McMahon refrigerator International-presentation

S. Sunahara, U. Mizutani

The 23rd International Conference on Low Temperature Physics　2002/08/20
Construction of a thermoacoustic Stirling cooler International-presentation

Y. Ueda, T. Yazaki, U. Mizutani

The 23rd International Conference on Low Temperature Physics　2002/08/20
Low-Temperature Specific Heat of overdoped Bi2201 Single Crystals International-presentation

H. Ikuta, M. Matsuura

The 23rd International Conference on Low Temperature Physics　2002/08/20
Thermodynamical Mode Selection Rule in Spontaneous Gas Oscillations International-presentation

Y. Ueda, T. Yazaki, U. Mizutani

The 17th International Congress on Acoustics　2001/09/02
Thermoacoustic Stirlng engine and cooler International-presentation

Y. Ueda, T. Yazaki, U. Mizutani

The 17th International Congress on Acoustics　2001/09/02
Thermodynamical Mode Selection Rule in Thermoacoustic Gas Oscillations International-presentation

Y. Ueda, T. Yazaki, U. Mizutani

First International Workshop on Thermoacoustics　2001/04/23
Relationship between the Temperature-Dependent Specific Heat of Regenerator Materials and Performance of a Gifford-McMahon Refrigerator International-presentation

S. Sunahara, H. Ikuta, U. Mizutani

The Sixth Joint Japanese-Sino Seminar on Cryocooler and its Applications　2000/08/20
Optimization of the Phase Angle between Oscillating Pressure and Displacement in a Gifford-McMahon Refrigerator International-presentation

S. Sunahara, U. Mizutani

The Sixth Joint Japanese-Sino Seminar on Cryocooler and its Applications　2000/08/20
Experimental Studies of the Enthalpy and Entropy Flows through the Regenerator of the GM Refrigerator International-presentation

Y. Hoshino, H. Ikuta, Y. Ohashi, T. Inoue, U. Mizutani

The Fifth Japanese-Sino Joint Seminar on the Cryocooler and its Applications　1997/09/16

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Industrial Property Rights 2

熱音響効果を利用した音波増幅・減衰器を備えた配管装置

琵琶哲志, 矢崎太一, 田代雄亮, 上田祐樹, 水谷宇一郎, 小塚基樹, 鷲見高雄, 熊澤克芳, 立花一志

特許第4035069号

Property Type: Patent
圧力変動と位置変動の位相差を利用した蓄冷式冷凍機およびその制御方法

琵琶哲志, 水谷宇一郎, 生田博志, 砂原茂幸

Property Type: Patent

Research Projects 17

複雑系科学の視点から熱音響自励振動を抑制する実用的な相互作用設計

杉谷栄規, 琵琶哲志, 小西啓治

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 基盤研究(C)

Institution: 大阪公立大学

2023/04/01 - 2027/03/31
液体ピストンエンジンと往復流型タービンを用いた単純構造の発電システムの開発

琵琶哲志, 高尾学

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

2023/04/01 - 2026/03/31
低温・低エネルギー密度の熱源で動作する音波エンジンの開発

琵琶哲志

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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液体ピストンスターリングエンジンに関するこれまでの知見をまとめて，設計のためのガイドラインとしてまとめた．このガイドラインでは，等価力学モデルに基づいて，装置サイズと発生可能な出力パワーに関する関係式を導出し，その条件のもとでエネルギー変換が最適化される蓄熱器の選び方を示した．また，とくに4ユニットで系を構成する場合について，加速度振幅が重力加速度の2倍程度を仮定し，直径106 mmのパイプで全体を構成し，1ユニット当たりの長さが5 m，高温部温度100℃，低温部温度23℃であれば，1ユニットあたりのエネルギー変換により50 Wの出力を見積もった．この半分が作動流体のエネルギーロスに消費されるとすると，1ユニット当たり利用可能な出力は25 Wであり，4ユニット全体では100 Wになると算出した．作動流体の熱力学的性質や，流路形状など多くのパラメータを持つ液体ピストンスターリングエンジンにおいて，その設計パラメータを試行錯誤的に繰り返しテストすることなく，一度に決定できることは設計，製作上の価値がある．ループと枝管で構成される液体ピストンスターリングエンジン（フルイダイン）について理論的動作解析を熱音響現象の視点から実施した．系は基本的には2自由度の振動系とみなすことができるが，枝管長さを適切に選ぶことで，二つの固有周波数を同一にすることができる．そしてまさにこの条件が，フルイダインがスターリングエンジンとして自発的に動作するために必要なことを明らかにした．またその結果を装置サイズや作動流体の物性値を用いて簡単な表式を導出することに成功した．その結果は実験的にも検証している．
Development of suppression method of acoustic oscillations by means of oscillation death

Biwa Tetsushi, Terata Kengo, Hyodo Hiroaki

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

2017/06/30 - 2019/03/31

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When a gas column confined in a resonator is subjected to a heat source, intense acoustic oscillations occur, which can be harmful in various industrial combustors. The objective of this study is to stop those oscillations with a simple and reliable method. We attempted to utilize oscillation death phenomenon occurring in coupled self-sustained oscillators, and introduced a gas-filled tube for mutual interactions between two acoustic oscillators. When two tubes were used, the oscillations were found to stop completely with specific combinations of the tube lengths.
Understanding of coupled thermoacoustic oscillators and their applications

Biwa Tetsushi

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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Thermoacoustic oscillations mean thermally-induced acoustic oscillations of a gas column. Understanding their nonlinear behaviors should lead to the development of various applications like acoustic heat engines and suppression tools of combustion instability. In this study, mutual interactions between thermoacoustic oscillators were introduced by using a connecting tube and a valve to successfully observe synchronization and oscillation-death phenomena. Also, chaos-chaos synchronization was demonstrated for the first time in the coupled thermoacoustic oscillators.
Understanding of nonlinear dynamics of natural engines and its application

BIWA Tetsushi

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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Objective of this study was to experimentally understand the nonlinear dynamics of thermally induced unstable oscillations known as thermoacoustic oscillations. When two thermoacoustic chaos oscillators are connected each other, chaos synchronization was observed for the first time in fluid system. Also when two thermoacoustic oscillators are connected via a needle valve, the oscillation was observed to stop when the frequency detuning was large. When the frequency detuning was zero, it was necessary to add a connecting tube to annihilate the oscillation. The evolution equation was experimentally derived which was able to describe oscillatory dynamics near the bifurcation point.
Acoustic Stirling engine: Novel development of Stirling engine

BIWA Tetsushi

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

2011 - 2013

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Objective of this study was to achieve a novel development on a Stirling engine technology by replacing oscillating solid pistons with oscillations of a gas column or with oscillations of a liquid column. The looped tube type thermoacoustic engine, which had been invented as a pistonless Stirling engine based on unstable oscillations of the gas column, was modified in this study by using a co-axial tube consisting of cylindrical tubes with different diameters. Also, in this study, a pistonless-Stirling engine was developed by using oscillation of a liquid column in a U tube. This type of the engine operates at significantly low frequency compared with that using oscillation of a gas column.
Observation of local energy conversion and entropy production in a thermoacoustic heat engine

BIWA Tetsushi

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

2008 - 2009

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Thermoacoustic energy conversion was experimentally studied through simultaneous measurements of pressure, velocity, and temperature oscillations in a gas-filled tube with axial temperature gradient. The phase difference between pressure and velocity was found out to be a key parameter governing the phasing of thermodynamic processes constituting a thermodynamic cycle. Also, the axial work flow (acoustic power) was found to increase in proportional to the local energy conversion rate that the gas executed. This results supports the thermodynamic approach to thermoacoustic phenomena.
音波エンジンにおける音響流の可視化とその制御方法の確立

琵琶哲志

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 若手研究(B)

Institution: 東北大学

2006 - 2007

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熱と音波の間のエネルギー変換現象である熱音響現象を利用すると,熱から音波を発生する音波エンジンや音波により冷凍を実行する音波クーラーが可能になる.これら熱音響機器は既存の熱機関と比較すると効率が低いが,これは熱音響エネルギー変換に本質的な問題があるわけではなく,進行波音波に伴って生じる定常的質量流(音響流)が引き起こす熱的損失が問題であると考えられている.しかし,直接的な観測に基づく音響流の定量的評価は未だに行われていない. 熱音響機器の性能向上を目標として,音響流の計測を通じてその制御方法を提案することを目的に実験的研究を遂行している.昨年度はループ型の配管を持つ進行波音波エンジンにおける音響流の観測を行い,進行波音波の伝搬方向に流れる音響流を確認した.この音響流が音波エンジンの効率を著しく下げる可能性があることも分かった.今年度はパルス管冷凍機プロトタイプを作成し,その内部の振動流体ダイナミクスの計測を行った.自作した空気を作動流体とするオリフィス型パルス管冷凍機はオリフィスバルブを最適に調整することでマイナス5度程度の低温が得られることを確認した.最適バルブ開度における流動状態をレーザードップラー流速計ならびにシート状レーザー光による可視化実験により調べた.その結果,最適開度では音響インピーダンスの位相角が最も小さくなることが分かった.この振る舞いは簡単な等価回路で再現できる.また可視化により大振幅では顕著な音響流が発生することも分かった.
熱音響現象を利用した新しい音響デバイスの評価技術の確立とその応用

琵琶哲志

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 若手研究(B)

Institution: 名古屋大学

2004 - 2005

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熱エネルギーから流体の自発的振動運動(音波)を発生することや音波を使った冷凍の実現など,熱と音波の間の相互エネルギー変換現象は熱音響現象と呼ばれる.特に進行波音波が関与する熱音響現象においては,振動流体はスターリングサイクルと同様の熱力学的サイクルを実行することが21世紀に入ってから実証され,注目を集めている.スターリングサイクルは可逆サイクルであるため,ピストンなどの可動部の代わりに音波を使った効率の良いエネルギー変換システムが構築できる可能性があるからである.本研究では,熱(熱源温度400℃)から動力として音波を発生し,その音波を使って低温(冷凍温度マイナス25℃)を生成する試作熱音響スターリング冷凍機を研究対象とし,これを新しい低温生成技術として発展させるために(1)圧力計測による音響パワーの測定手法を確立し,(2)測定結果に基づいて性能向上を果たすことを目的とした. (1)音響パワーは管内音波中の圧力変動(音圧)と流速変動(音響粒子速度)で与えられるが,試作機は加圧ガスを利用するため,その流速変動(~200Hz)の計測は困難であった.そこで管内圧力を複数箇所で同時に計測することで,音響パワーの管軸方向の分布を明らかにする手法の開発に取り組んだ(平成16年度).テスト共鳴管に対して適用し,その有効性を実証した. (2)試作熱音響スターリング冷凍機の音波発生部において音響パワーと熱エネルギーの計測を行った結果,熱音響エネルギー変換効率はカルノー効率の25%が達成可能なことが分かった.これは既存のエネルギー変換機器に匹敵する値である.その一方で,音響流と呼ばれる定常的質量流が電気ヒータによる発熱量を運び去るため,発熱量の30%しか実質的にエネルギー変換に寄与しないことが明らかになった.音響的に透明なゴム膜を利用することで音響流を抑制し,冷凍性能を向上させた.
Studies of alloy phase stability in relation to the Hume-Rothery rule and development of new Al-based thermoelectric materials

MIZUTANI Uichiro, TAKEUCHI Tsunehiro, SATO Hirokazu, NISHINO Yoichi, IKUTA Hiroshi, BIWA Tetsushi

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

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

Institution: Nagoya University

2003 - 2004

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The present work aimed at exploring physics behind the Hume-Rothery rule by performing the first-principles band calculations and evaluating thermoelectric properties of quasicrystals and their approximants and Fe_2VAl compounds, all being characterized by the possession of the pseudogap at the Fermi level. The main results obtained in this project are listed below. (1)The electronic structure of the Al-Li-Cu 1/1-cubic approximant has been calculated in the context of the LMTO-ASA method in combination with the NFE model. We proved that the pseudogap is formed as a result of the interaction of electrons at the Fermi level with (631), (543), (710), (550) zone planes. (2)We have measured the electronic specific heat coefficient, Seebeck coefficient, electrical resistivity and thermal conductivity of the Al-Re-Si,Al-Mn-Si,Al-Pd-Mn-Re-Si and Al-Mn-Re-Si approximants and revealed how the pseudogap structure across the Fermi level determines the thermoelectric characteristics of these pseudogap-bearing systems. (3)We succeeded in swinging a sign of the Seebeck coefficient from a positive to negative value (-140μV/K) by substituting Si for Al and Ti and Mo for V in the Fe_2VAl system, respectively. In the Fe_2VAl, spin fluctuations caused by Fe atoms introduced into the V site are believed to give rise to an enhancement in resistivity, thereby leading to a poor performance of thermoelectric characteristics. To get rid of this difficulty, we synthesized the (Fe-Ru)_2VAl alloys and revealed that a dramatic decrease in magnetization results in a substantial decrease in resistivity and magnetoresistance. This was taken as a proof that the Fe atoms on the V-site contribute to degrade the thermoelectric characteristics of this system. (4)The FLAPW band calculations have been performed for Cu_5Zn_8,Cu_9Al_4,TM_2Zn_<11>(TM=Ni,Pd,Co,Fe) gamma-brasses. The Fourier spectrum analysis for wave function sustaining the pseudogap at the Fermi level clearly demonstrated that (411), (330) zone are indeed responsible for the formation of the pseudogap to stabilize the unique complex structure at specific electron concentration.
THERMOELECTRIC MATERIALS IN PSEUDOGAP SYSTEMS

MIZUTANI Uichiro, BIWA Tetsushi, TAKEUCHI Tsunehiro, IKUTA Hiroshi

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

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

Institution: NAGOYA UNIVERSITY

2001 - 2002

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Attention has been focused on the development of highly efficient thermoelectric materials to resolve energy shortage problem possibly encountered in the midst of the 21 century. The magnitude of the Seebeck coefficient, which serves as the most important factor to raise the efficiency of the thermoelectric performance, is known to be decided by electronic states at the Fermi level. A high Seebeck coefficient will be achieved in a system where the electron density of states at the Fermi level is low and the slope is steep, provided that the relaxation time approximation is valid and that the system is isotropic. In the present work, we carried out the research to develop new thermoelectric materials in systems where the pseudogap exists at the Fermi level and, hence, satisfy the conditions above. The dimensionless figure of merit ZT was studied in substances, which include Co-oxides, Fe2VA1 and Al-Re-Si 1/1-cubic approximants. Its value has reached almost unity in all these systems. In the Al-Re-Si system, the crystal structure has been precisely determined and electronic structure was calculated by using the atomic structure thus determined. The observed Seebeck coefficient and its temperature dependence were successfully interpreted by using the electronic structure thus obtained. The Seebeck coefficient in Cu-oxides was also calculated by using the electronic structure determined from the angle-resolved photoelectron spectroscopy measurements. The measured Seebeck coefficient and its temperature dependence were again well reproduced. Our technique can be applied to any materials characterized by a metallic conduction. We believe that a new technique to design a highly efficient thermoelectric material has been established in this project on the basis of the detailed study on the electronic structure near the Fermi level within the framework of the Boltzmann transport equation.
低次元物質の熱電変換材料としての可能性

水谷宇一郎, 琵琶哲志, 竹内恒博, 生田博志

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 萌芽的研究

Institution: 名古屋大学

2000 - 2001

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本年度は,遷移金属酸化物の熱電特性の評価を行った.特に最近,Co酸化物が注目を集めていることから,(Ca_<1-x>Bi_x)_3Co_4O_9,(Ca,Sr,RE)_<n+2>Co_<n+1>O_<3n+3>,およびRECoO_3を選択し、それぞれの物質に対して詳細にゼーベック係数や電気伝導率のバンド幅やドープ量依存性の評価を行った.また,Mn酸化物であるREMnO_3とRE_3Mn_2O_7に対して光電子分光法により電子構造を解明し,大きなゼーベック係数を発現する可能性を考察した.(Ca_<1-x>Bi_x)_3Co_4O_9,(Ca,Sr,RE)_<n+2>Co_<n+1>O_<3n+3>およびRE_3Mn_2O_7は2次元的な伝導面を有している.一方,RECoO_3とREMnO_3は3次元的な伝導を示す.これらの物質群の示す熱電特性を比較することにより,熱電特性に及ぼす次元性の効果を議論した. キャリアーをドープしていないRECoO_3は高いゼーベック係数を呈するが,絶縁体的な電気伝導特性を示す為,熱電変換材料として適していないと判断された.しかし、この系にわずかにキャリアを注入すると,ゼーベック係数と抵抗率は双方ともに低下するが,比抵抗の低下率がゼーベック係数の低下量よりも遥かに大きく,熱電変換材料として有望であることが判明した.一方,(Ca_<1-x>Bi_x)_3Co_4O_9,(Ca,Sr,RE)_<n+2>Co_<n+1>O_<3n+3>では高い熱電特性を示す試料を発見するには至らなかった.Mn系酸化物では,3次元的なREMnO_3,2次元的なRE_3Mn_2O_7共にフェルミレベル近傍に状態密度の落ち込みが存在することを明らかにした.このような状態密度の落ち込みは擬ギャップと呼ばれ,擬ギャップがフェルミレベルに存在すると,大きなゼーベック係数を発現する可能性が極めて高い.すなわち,擬ギャップをフェルミレベルに有するMn酸化物は,熱電変換材料として利用できる可能性が高いと判断した.本研究では,2次元材料の3次元材料に対する優位性を示すには至らなかったが,上記に示した通り,電気伝導性遷移金属酸化物が熱電変換材料として極めて有望であることを明らかにできたと考えている.
蓄冷式冷凍機における積層型蓄冷器の特性評価とその高性能化

琵琶哲志

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 奨励研究(A)

Institution: 名古屋大学

2000 - 2001

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蓄冷式冷凍機ではピストンやディスプーレーサーなどの可動部が行う膨張仕事と引き換えに熱を外界から吸収すると説明されてきた.しかしながら,低温部分に全く可動部を持たない蓄冷式冷凍機であるパルス管冷凍機が従来の蓄冷式冷凍機と同様の性能を示す事実は,蓄冷式冷凍機の冷却のメカニズムをより深く理解する必要があることを示している. 本研究では熱音響現象の視点から蓄冷式冷凍機を眺め,その冷凍能力の向上を目指してきた.熱音響現象では振動する流体と流路壁の間の熱交換により熱輸送が生じる.この際に,この熱交換が準静的に行われるか,不可逆的に行われるかが重要な問題となる.当然,準静的な熱交換が行われる時,熱機関としては最も効率が高くなる. ギフォードマクマホン式冷凍機は,すでに実用化もされている蓄冷式冷凍機であるが,蓄冷器内部で行われる蓄冷材と作動流体であるヘリウムガスの間の熱交換過程に関しては未だに十分に分かっていない.そこで本研究では,異なる材料,および粒径の蓄冷材に関してその熱交換能力を調べた.その結果,現在もっとも良く使われている粒径である0.2mmの球状粉では10Kレベルの温度では十分に熱交換できないことが分かってきた.これは蓄冷材が鉛でも磁性蓄冷材でも同様であった.この点を解決するために我々はヘリウムガスの圧力変動と周期的な位置変動の間の位相差をパラメータとして運転する方法を提案した.この方法を用いれば,不可逆的な熱交換過程が顕著になる温度領域でも比較的大きな冷凍能力が得られる.
Improvement of the fracture toughness and trapped field of bulk high temperature superconductors by controlling the microstructure

IKUTA Hiroshi, BIWA Tetsushi

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

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

Institution: Nagoya University, Associate Professor, Research Associate

2000 - 2001

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The superconducting properties of bulk high temperature superconductors, such as the trapped field, had already reached a very high level. However, it has been commonly observed that the samples are easily broken by the magnetic pressure of the trapped fluxes or by an abrupt heat cycling. The microstructure of melt processed.bulk superconductors is influenced by the contents of each phase as well as by the preparation condition, which in turn affects the fracture toughness. Therefore, we prepared samples by varying the composition and preparation condition, and examined the microstructure and the fracture toughness. The major results are summarized in the following. We succeeded in the preparation of a single-grain, c-axis aligned, Nd-based bulk superconductor that is 30 mm in diameter for the first time. The trapped field was larger than that of a Sm-based sample that contains the same amount of Ag. We also studied the relation between the atmosphere during the melting and the formation of voids, and succeeded in the elimination of voids by melt-processing the samples in an oxygen-gas flowing atmosphere or vacuum. It was also confirmed that the samples show high performance if the atmosphere were switched to an Ar-gas flowing one during the growth process. The average particle size of the Sm211 phase in a sample prepared with 211-phase powders that were treated with ball-milling was 0.7 ^m, and the trapped field increased compared to samples prepared with the same condition using 211-phase powders that were not ball-milling treated. We also studied the oxygenation process of Sm- and Y-based samples to establish an efficient oxygen treatment for dense samples. It was found that the diffusivity of oxygen is influenced by the difference in the microstructure rather than the difference of the system, Ag-added samples require a longer oxygen treatment because of the less amount of voids, and a low temperature treatment below 350aC is important for Sm-based samples. We established the melt-processing conditions of the Nd-Eu-Gd system up to 36 mm in diameter, for which the trapped field was 1.4 T at liquid nitrogen temperature and 8.2 T at 20 K. For the Dy-based system, the trapped field reached 5.7 T at 18 K even with a small sample whose diameter was 18 mm, and the trapped field of a CeO2-added Y-based sample that is 18 mm in diameter reached 6.2 Tat25K.
Ni系酸化物の高濃度キャリア領域の物性と磁気抵抗

生田博志, 琵琶哲志, 竹内恒博

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 特定領域研究(A)

Institution: 名古屋大学

2000 - 2001

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従来からLa_<2-x>Sr_xNiO_4には多数の研究があるが、単結晶育成はx<0.6でしか報告されていない。これに対し、我々はREサイトを置換したRESrNiO_4(RE=Pr,Nd,Sm,Eu)単結晶の作製に成功した。さらに、NdSrNiO_4では2K,9Tで約85%もの負の磁気抵抗効果を観測したのに対し、RE=Nd以外の磁気抵抗効果は同じ条件で1%程度しかない。そこで、本年度はキャリア量を変化させて物性の全体像を把握することと、Nd系で観測された大きな負の磁気抵抗効果の発現機構を探るためにRE_<2-x>Sr_xNiO_4(RE=Pr,Nd,Sm)単結晶を作製し、輸送現象、磁性、結晶構造、電子構造などを調べた。 Nd_<2-x>Sr_xNiO_4の抵抗率は、x=0.5を境に高ドープ領域では面内、c軸方向共に急激に小さくなった。また、0<0.5では抵抗率の異方性が小さいが、これはLa系に比べて面内抵抗が大きいためである。さらに、x=0.33の抵抗率の温度依存性はRE=Pr, Ndは電荷整列相の存在を示唆しているが、Sm系ではそのような振る舞いは観測されなかった。これはキャリアの動き易さを反映していると考えられる。一方、RE=Ndの磁化率は低温でピークを持ち、この温度以下で抵抗率が特に急激に増大したが、他のRE元素の系ではこのような振る舞いはみられなかった。Nd系ではSrの広い範囲で大きな磁気抵抗効果を観測した。さらに、Nd系の分光測定の結果からNd, Ni, Oが混成軌道を形成していることが示唆された。これらの実験結果から、Nd4f電子と伝導電子の間のcf相互作用が、RE=Ndに特有な急激な抵抗率の上昇や磁気抵抗効果、磁化率の振る舞いに関わっていると考えられる。また、Pr系ではむしろ近藤効果と競合するRKKY相互作用が働いていることが考えられる。
熱音響現象の基礎と応用 Competitive

1999/04 -

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Social Activities 15

廃熱，音に変えれば．．．エネルギーに再利用，研究進む

2017/04/16 -
出張講義

2015/07/29 -

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出張講義を実施した
オープン講義

2015/07 -

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オープンキャンパスにおける公開講義の実施
出張講義

2014/11/18 -

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出張講義を実施した
出張講義

2014/10/03 -

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出張講義を実施した
出張講義

2013/12/05 -

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出張講義を実施した
出張講義

2013/09/11 -

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出張講義を実施した
出張講義

2013/04/26 -

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出張講義を実施した
「熱」を「音」にエネルギー機器の概念変える「熱音響」

2010/04/09 -
仙台市産業振興事業団主催産学連携セミナー「寺子屋せんだい」

2009/01/19 -

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「音を使った熱機関〜熱で音を発生し，音で冷却する〜」
技術情報センター主催セミナー

2005/08/24 -

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「熱音響現象のエネルギー変換機器への応用」
ISS産業科学システムズ主催セミナー

2005/04/08 -

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「熱音響現象の基礎と熱音響デバイスの開発動向及び今後の課題」
かなれ科学遊び教室

2004/08/07 -

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「音の科学を楽しむ〜音の力〜」講演
日本ガイシ本社セミナー

2002/05/31 -

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「熱音響現象の基礎」
日本機械学会エンジンシステム部門企画

2001/06/29 -

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講習会「熱音響現象とそのエネルギー変換機構」

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Media Coverage 5

サイエンスZERO：聞くだけじゃない！秘めたる音の可能性

NHK教育テレビ

2009/10/24

Type: TV or radio program
北野大のエーコロジー

青森朝日放送

2005/03/29

Type: TV or radio program
ザ・ブレインサミット３

東京放送（TBS）

2005/03/09

Type: TV or radio program
音で冷やす

朝日新聞

2003/02/19

Type: Newspaper, magazine
低コスト・簡単構造で冷熱

日刊工業新聞

2003/02/05

Type: Newspaper, magazine

Other 12

自然エンジンを使った環境調和型低温排熱回収技術の研究

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気柱管の一部に，ある臨界温度差以上の温度差を与えると，熱音響自励振動と呼ばれる気柱振動が自発的に生じる．この気柱振動の音響パワーを動力として利用する熱機関が自然エンジンである．このタイプの熱機関の利点は，固体ピストン等の可動部品を必要としない点である．本研究では，自然エンジンを設計するための基盤技術を構築することを目標とした．より具体的には，自然エンジンを基本的構成要素に分割し，そのそれぞれの性能を個別に評価することで，組み合わせた際の特性の理解と向上を実現することにした．自然エンジンは，動作状態をチューニングするための調整部品を持たず，装置を作成したあとでその形状などを最適化するのが困難であるためである．また性能評価に必要不可欠な音場計測技術の開発も実施した．従来型の手法では加圧気体を充填した管内の局所的な音場を決定するのが困難であったためである．
熱音響エネルギー変換を用いた冷却技術開発

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•進行波音波クーラーの開発計画を遂行中．
熱音響デバイスの基礎と応用

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熱音響デバイスの基礎と応用
進行波音波を使った熱音響エネルギー変換技術の実用化研究

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•熱音響効果を利用した進行波音波増幅において本質的な役割を満たす無次元数ωτ（ωは角振動数，τは流体の熱緩和時間）を実験的に見いだした． •多段蓄熱器を用いた進行波音波増幅を実証し，低温度差で高強度音波を実現する方法を提案した． •圧力・流速・温度を同時に計測する多元的熱流体振動計測法を確立した．
音波冷凍機の冷凍メカニズムの実験的理解

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•音波クーラーの一つであるパルス管冷凍機において利用される可動部品を使わない流体制御機構を圧力と流速の同時計測により明らかにした．
熱音響エンジンを利用した新しい低温生成装置の開発

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熱音響エンジンを利用した新しい低温生成装置の開発
エネルギー流による非線形音響現象の実験的解明

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•気柱共鳴管内に生じる衝撃波音波に対して仕事流計測を行い，基本振動モードおよび２次振動モードのモード間相互作用を初めて観測した．
熱音響現象を利用した音波の増幅と減衰に関する研究

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気柱共鳴管内に生じる定在波音波の特殊な場所（圧力の腹）に温度勾配のある蓄熱器を置くことで，音波増幅および減衰を実証した．音波の定在波成分を利用することで，進行波のみに頼るよりもより大きな増幅率が得られることを実証した．
熱音響デバイスに関する基礎的研究

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•直径100mmの配管を用いた大型の熱駆動型熱音響冷凍機を試作した．試作装置は可動部品のない冷凍機として，新聞やテレビ等で報道された．
大出力熱音響冷凍機の開発〜可動部のない新しい冷凍機の実用化を目指して〜

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大出力熱音響冷凍機の開発〜可動部のない新しい冷凍機の実用化を目指して〜
熱と音の相互変換を利用した可動部のない熱音響冷凍機の開発

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進行波音波エンジンの音場計測を行い，エネルギー変換メカニズムと音波冷凍に適した場所を特定した．第2蓄熱器を音波エンジン内に挿入することで全く可動部のない冷凍機プロトタイプを開発した．
音波と熱の相互変換を利用した可動部のない熱音響デバイスの基礎的研究

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音波と熱の相互変換を利用した可動部のない熱音響デバイスの基礎的研究

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