2023 Fiscal Year Final Research Report
Law of the wall over riblet surface with the local wall shear stress measured by drag balance device
| Project/Area Number |
20H02069
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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 | Yamaguchi University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
鈴木 博貴 岡山大学, 環境生命自然科学学域, 准教授 (10626873)
亀田 孝嗣 近畿大学, 工学部, 教授 (70304491)
笹森 萌奈美 国立研究開発法人宇宙航空研究開発機構, 航空技術部門, 研究開発員 (80836065)
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| Project Period (FY) |
2020-04-01 – 2024-03-31
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| Keywords | 壁面せん断応力 / 抵抗低減 / 直接測定 / リブレット / 境界層 / 炭酸ガス排出低減 |
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| Outline of Final Research Achievements |
Experimental study was conducted to obtain quantitative data to confirm the reduction of the wall shear stress by riblets and to verify the wall law. In order to obtain experimental data at practical high Reynolds numbers for riblets, a direct measurement device for wall shear stress with nano gap dimensions and sufficient accuracy to confirm the drag reduction rate was developed. In the turbulent boundary layer developed on smooth and riblet surfaces, the local wall shear stress, mean velocity, and turbulence intensity distribution were measured. It was confirmed that the wall shear stress is reduced by the riblet surface, and the reduction rate was confirmed by direct measurement. It was confirmed that the logarithmic velocity distribution is established on the riblet surface, and it was shown that the intercept change can be understood by the deviation between the velocity distribution and the virtual origin of the cross flow.
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| Free Research Field |
流体工学
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| Academic Significance and Societal Importance of the Research Achievements |
航空機における摩擦抵抗低減が実現できれば、石油燃料消費および炭酸ガス放出量の低減に大きく貢献する．リブレットはその最有力候補であるが，事業化するには設置方法の検討，実際の航空機における圧力勾配などの影響への対応と改良が必須となる。従来の研究において摩擦抵抗の低減は直接的ではなく，平均速度分布を利用するなどの非直接的な計測法により確認されている．非直接的な計測法は何らかの制約条件が付帯しており，圧力勾配や発達距離の影響などに対応できない．抵抗低減を確認できる精度で壁面摩擦抵抗の直接抵抗が可能となれば，前提条件を必要とせず，改良されたリブレットの性能評価が容易となり，研究開発が可能となる．
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