| Project/Area Number |
18K03945
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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 | University of Toyama |
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Principal Investigator |
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| Project Period (FY) |
2018-04-01 – 2024-03-31
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| Project Status |
Completed (Fiscal Year 2023)
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| Budget Amount *help |
¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000)
Fiscal Year 2020: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2019: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2018: ¥2,730,000 (Direct Cost: ¥2,100,000、Indirect Cost: ¥630,000)
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| Keywords | 超音速ジェット / マッハ波 / 騒音抑制 / 線形安定性解析 / DNS / 騒音低減 |
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| Outline of Final Research Achievements |
Linear stability analysis and direct numerical simulations were used to investigate the characteristics of unstable waves (helical modes) and their effects on transitions and acoustic radiation characteristics due to nonlinear development for the purpose of supersonic jet noise suppression at M=2.Linear stability analyses show that helical modes with low azimuthal wavenumber radiate pressure fluctuations far from the jet, while modes with high circumferential wavenumbers do not radiate strong pressure fluctuations jet outside.Simulations also confirmed that adding a combination of helical modes to the jet reduces the level of radiated pressure fluctuations compared to the case where no helical modes are added.The combination of asymmetric helical modes (m=2 and m=4) resulted in the lowest pressure fluctuations.
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| Academic Significance and Societal Importance of the Research Achievements |
本研究の特色は、高い移流マッハ数の超音速円形ジェットに対し、速度分布の持つ不安定波の特性を利用した、ノズル部における能動的な騒音低減手法の可能性を理論的・数値的に探ることである。この不安定波による抑制手法が効果的であれば、ノズル部に与える不安定波の振幅は微小でよいことから、ノズル部に設置するアクチュエータも小型化が可能と考えられる。そのため従来の手法に比べ、推力低下を招かない、広範なマッハ数に対応した、高性能騒音抑制ノズルの開発に貢献できると予想する。さらに、ジェットの拡散（中心速度の低下）が促進できれば、空港での離発着時間短縮の妨げとなる残留ジェット気流の抑制にも貢献できる可能性がある。
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