| Project/Area Number |
16K18008
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Fluid engineering
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| Research Institution | University of Tsukuba |
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Principal Investigator |
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Project Status |
Completed (Fiscal Year 2018)
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| Budget Amount *help |
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2017: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2016: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000)
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| Keywords | 音速 / ボイド率 / 気泡流 / 圧力波 / ソリトン / 衝撃波 / 非線形波動 / 非線形音響学 / 粘性 / 熱伝導性 / 散逸性 / 流速 / 高濃度気泡流音響学 / 気泡力学 / 非線形音波 / 多重尺度法 / 非線形波動方程式 / マイクロバブル / ベンリュリ管 / 縮小拡大管 / 均質流モデル / 混合体モデル / ベンチュリ管 / 不均質 |
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| Outline of Final Research Achievements |
A large difference between theoretical and experimental values of speed of sound in bubbly flows in a high void fraction should be corrected. The purpose of this study is to improve this difference by integrating a theory and an experiment. The main results are as follows: (i) The observation of bubble collapse, and the measurement of speed of sound and the pressure distribution, were experimentally performed; (ii) Nonlinear wave equations were theoretically derived especially focusing on a wave dissipation effect and a nonuniform distribution of flow velocity; (iii) The pressure distribution and the speed of sound were numerically predicted by solving the above-mentioned nonlinear wave equations; (iv) Theoretical and numerical values almost coincided with experimental values.
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| Academic Significance and Societal Importance of the Research Achievements |
気泡を含む水の流れの研究において，気体の占める割合は1 %程度に小さいことが当たり前であったが，泡の有効活用を目指す観点からは，沢山の泡を含む「高濃度気泡流」に挑む必要がある。しかし，10 %を超える高濃度の場合，音速の理論予測値と実験事実の間に大きな乖離があった。本研究は，厳密な数学的理論解析と精密な計測を適切に組み合わせて，上記乖離の原因を指摘すると同時に，乖離の多くの解消に成功した。
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