| Project/Area Number |
21K03850
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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 Yamanashi |
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Principal Investigator |
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Project Status |
Completed (Fiscal Year 2023)
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| Budget Amount *help |
¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
Fiscal Year 2023: ¥390,000 (Direct Cost: ¥300,000、Indirect Cost: ¥90,000)
Fiscal Year 2022: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2021: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000)
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| Keywords | 乱流 / 噴流 / 対向噴流 / よどみ点 / 乱流界面 / パッシブスカラ / PLIF / 物質拡散 / 高ペクレ数 |
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| Outline of Research at the Start |
噴流が一様流に対向衝突する流れ（対向噴流）は下流域によどみ点が存在し，またその付近が乱流（噴流）と非乱流（一様流）の界面になるという興味深い物理的特徴をもつ．よどみ点流れを含む流れの幾何的構造や乱流界面は運動量や物質の乱流輸送に大きな影響を与えることが知られている．そこで，本研究では，2種類の蛍光物質の濃度場と速度場を同時計測できる2色PLIF/PIVシステムを開発することで，流れの幾何構造の識別と物質境界の同時検出を行うことを目指す．これにより，物質境界と乱流／非乱流界面との関係を調べ，高ペクレ数スカラ物質の混合過程に及ぼす流れの幾何構造の影響を明らかにする．
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| Outline of Final Research Achievements |
In the first year, several fluorescent dyes and optical filters with absorption wavelengths compatible with the newly purchased red laser and the existing pulse-emission green laser were selected, and the relationship between concentration and fluorescence intensity of selected dyes was investigated. Due to the failure of the green laser, the second year was limited to experimental preparation. In the final year of the project, interface detection experiments in a normal round jet were conducted for both laminar and turbulent flows. Different fluorescent dyes were mixed with the jet and ambient fluid, and the fluorescence from each dye was captured by a high-speed camera. Although the contrast of the fluorescence image was insufficient due to the low intensity of the substituted green laser, the interface of the laminar jet was successfully detected. For comparison, visualization experiments of annular jets were performed, and their results were presented in a scientific conference.
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| Academic Significance and Societal Importance of the Research Achievements |
スカラ場の濃度がゼロとなる境界で噴流の乱流域と非乱流域の界面を近似するという考え方は単純であり，過去に多く採用されている．しかし，ゼロへと漸近していく濃度場から濃度ゼロの境界線を取り出すことは困難であることから，実際にはしきい値が設けられ，それが曖昧さの要因となる．本研究手法では，噴流と周囲流体に発色が異なる二種類の蛍光染料を混入し，両染料からの蛍光画像を重ねることで，しきい値を設けなくとも両者の境界がより鮮明に得られることが期待できる．さらに，速度情報を同時取得する2色PLIF/PIV計測システムへの拡張も可能である．界面と速度場を同時計測した研究は世界的にも見当たらず，学術的意義は大きい．
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