2021 Fiscal Year Final Research Report
Application development of subcritical transitional flow with laminar-turbulent coexistence
| Project/Area Number |
19H02071
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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 | Tokyo University of Science |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
川口 靖夫 東京理科大学, 理工学部機械工学科, 教授 (20356835)
福留 功二 東京理科大学, 工学部機械工学科, 助教 (70710698)
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| Project Period (FY) |
2019-04-01 – 2022-03-31
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| Keywords | 亜臨界遷移 / 壁乱流 / DNS / 環状流 / 非相似性 |
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| Outline of Final Research Achievements |
We have investigated the reverse transition from turbulent to laminar flow in various annular and channel flows, the so-called subcritical turbulent transition, and clarified the characteristics and universality of laminar-turbulent coexistence and the limiting conditions for maintaining a turbulent state even locally. For example, we succeeded in the first experimental demonstration of the helical shape of localized turbulence in an annular Poiseiuille flow between two concentric cylinders by visualization, and revealed its high heat transfer characteristics by direct numerical simulation. In addition, we found that dissimilarity between momentum and heat transport (heat transfer dominance) occurs in a spatially growing turbulent spot.
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| Free Research Field |
熱流体力学
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| Academic Significance and Societal Importance of the Research Achievements |
環状流や平行平板間流は，熱交換器やフィンに見られる規範的な流路形態であり，これらに見られた現象は広く多くの実用場面でも生じるものである．亜臨界乱流遷移および臨界条件を明かにすることは，熱交換器の性能，ひいては発電プラントの安全性等に及ぶ重要な課題である．また，亜臨界乱流遷移や乱流維持限界は，流体力学分野における古くからの難問であり，当研究成果はその解決に大きな貢献をもたらしている．特に，乱流の起源や厳密解の解明に繋がるものと期待できる．
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