2021 Fiscal Year Final Research Report
Study on flow structure and atomization mechanism of multiphase flow in a converging-diverging nozzle
Project/Area Number |
19K04210
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Research Category |
Grant-in-Aid for Scientific Research (C)
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Allocation Type | Multi-year Fund |
Section | 一般 |
Review Section |
Basic Section 19020:Thermal engineering-related
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Research Institution | University of Tsukuba |
Principal Investigator |
Kaneko Akiko 筑波大学, システム情報系, 准教授 (40396940)
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Co-Investigator(Kenkyū-buntansha) |
阿部 豊 筑波大学, システム情報系, 名誉教授 (10241720)
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Project Period (FY) |
2019-04-01 – 2022-03-31
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Keywords | ベンチュリ管 / 微細気泡 / 微粒化 / キャビテーション |
Outline of Final Research Achievements |
In order to establish the shrinking-expanding tube as an atomization device, an experimental study was conducted to elucidate the atomization phenomena of solids and bubbles in response to the flow field in the shrinking-expanding tube. As a result, using allophene as the solid particle, the allophene was atomized downstream of the bubble collapse position, suggesting that the pressure wave generated by bubble atomization may contribute to the atomization of the allophene. For bubble refinement, the amount of generated vapor was calculated based on experimental and estimated values of void fraction, and it was clarified that bubbles became smaller under conditions with a higher ratio of generated vapor. It was suggested that rapid contraction of bubbles is less likely to occur under high vapor flow rate conditions, which may be one of the factors preventing bubble refinement.
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Free Research Field |
流体工学、混相流工学
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Academic Significance and Societal Importance of the Research Achievements |
本研究によりこれまで提案してきたベンチュリ管式微細気泡発生装置が気泡の微細化のみならず、固体粒子の粉砕に寄与することを示した。また、微粒化のみならず同時に発生する微細気泡との相乗効果で、微粒子を遠方場まで輸送する機能を付加するなど、工業的に多岐にわたる利用可能性を示した。気泡の微細化においては、混相流の相変化という極めて複雑な現象について解明を試み、実験的にキャビテーションが生じる可能性を示した。また、溶存ガス濃度の影響についても考察し、それぞれが発生気泡径に影響を及ぼすことを示した。これらはさらなる研究が必要ではあるものの、混相流の基礎物理の解明に資する結果である。
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