2023 Fiscal Year Final Research Report
Wind tunnel experiments as framework of boundary layer transition prediction using a new disturbance extraction method
| Project/Area Number |
20K04262
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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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 | Shinshu University |
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Principal Investigator |
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| Project Period (FY) |
2020-04-01 – 2024-03-31
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| Keywords | 乱流 / 境界層 / 主流乱れ / 層流乱流遷移 / 非線形 / 線形応答 |
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| Outline of Final Research Achievements |
A boundary layer on the surface of an object in a flow, undergoes a transition to turbulence downstream. The transition causes high friction of the object, so delaying the transition can reduce drag on transport equipment such as passenger planes. The receptivity process, in which turbulence around an object (free stream turbulence) enters the boundary layer via the leading edge of a wing is difficult to analyze because of is a nonlinearity. This study attempted to elucidate the receptivity process experimentally using a linear response extraction method, which has been successfully used in turbulence research. Artificial disturbance was superimposed on the free stream turbulence, and the periodic components were obtained by phase averaging the velocities in the boundary layer. The results showed that the periodic components respond linearly to the disturbance intensity, indicating that the linear response extraction method can be used as a powerful tool in receptivity studies.
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| Free Research Field |
流体工学
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| Academic Significance and Societal Importance of the Research Achievements |
境界層が層流から乱流へと遷移すると，壁面における摩擦や熱交換が数倍も大きくなるため，遷移の制御や予測は工業上の設計で重要である．しかし，遷移予測法は未だ確立されてない．本研究では遷移予測法の開発の妨げとなっていた前縁受容性の解明に対し，線形応答抽出法が適用できることを証明した．今後，さまざまな状況の受容過程に対し線形応答抽出法を用いた研究を行えば，遷移の制御や予測が可能となる．遷移制御を利用すれば大幅な摩擦抵抗の軽減が見込まれ，流体機械の高効率化，特に旅客機などの低燃費化につながると考えられる．
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