2022 Fiscal Year Final Research Report
Unravelling nonlinear phenomena in thermoacoustic self-excited oscillations−aiming at promotion and suppression of the oscillations−
| Project/Area Number |
18H01375
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Review Section |
Basic Section 19010:Fluid engineering-related
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| Research Institution | Osaka University (2021-2022)
Kansai University (2018-2020) |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
清水 大 福井工業大学, 工学部, 教授 (40448048)
板野 智昭 関西大学, システム理工学部, 教授 (30335187)
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| Project Period (FY) |
2018-04-01 – 2022-03-31
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| Keywords | 熱音響 / 熱流の不安定化 / 臨界条件 / ループ管路 / 直管 / 自励振動 / 振動発電 / エネルギー・ハーベスティング |
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| Outline of Final Research Achievements |
A simplified and systematic theory has been developed to unravel thermoacoustic, self-excited oscillations resulting from an instability of a heat flow through a still gas in a tube. In a framework of fluid dynamics, asymptotic methods are exploited to derive one-dimensional equations taking account of the essence of the phenomena. They are applied to derive marginal conditions of instability and also to simulate numerically ensuing nonlinear phenomena. Novel knowledge on the promotion or suppression of instability has been obtained.
With an application for renewable energy, in parallel, energy harvesting has been attempted by exploiting the oscillations. One method is to drive a linear generator to generate electricity, while the other is to rotate the Wells turbine by oscillatory flow to drive a DC generator connected coaxially. As long as the atmospheric air is used, the output power is a few watts in both cases, but this will be expected to be enhanced if the air is pressurized.
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| Free Research Field |
熱流体力学
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| Academic Significance and Societal Importance of the Research Achievements |
持続可能な社会の実現のため様々なエネルギー源が研究されており，太陽熱や地熱，低温廃熱の利用を想定した熱音響振動によるエネルギー・ハーベスティングが注目されている．実現には大出力化が必須であり，これには現象の定量化が不可欠である．本研究は，熱流体力学を基礎として，現象の本質を捉えた理論の構築を目指してきた．この体系が概ね完成し，現象の解明や定量化に用いることができる．
一方，振動エネルギーを発電により取り出す実験も並行して行った．振動でリニア発電機を駆動する方法の他に，振動流によりウエルズ・タービンを回転させ同軸に配置した直流発電機を駆動させ，実際に発電できることを確認し大出力化への知見を得た．
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