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Subcritical Transition in Boundary Layers

Research Project

Project/Area Number 62550049
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field Aerospace engineering
Research InstitutionUniversity of Osaka Prefecture

Principal Investigator

NISHIOKA Michio  College of Engineering, University of Osaka Prefecture, 工学部, 教授 (60081444)

Co-Investigator(Kenkyū-buntansha) ASAI Masahito  College of Engineering, University of Osaka Prefecture, 工学部, 助手 (00117988)
Project Period (FY) 1987 – 1988
Project Status Completed (Fiscal Year 1988)
Budget Amount *help
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1988: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1987: ¥1,600,000 (Direct Cost: ¥1,600,000)
KeywordsBoundary Layer / Laminar-Turbulent Transition / Subcritical Reynolds Number / Hairpin eddies / Regeneration of hairpin eddies / ヘアピン渦 / 乱流構造 / 乱流遷砂 / 外乱 / 前縁の受容性 / 縦渦 / 層流から乱流への遷移 / 境界層の遷移 / 流れの安定性 / 遷移の予測 / 剥離 / 前縁剥離 / 剥離泡
Research Abstract

The present study is concerned with the laminar-turbulent transition in boundary layer flows at subcritical Reynolds numbers. The subcritical transition can occur along cascade blades in various turbo-machinaries because of strong disturbance conditions, and it has a great effect on their performance. However, our understanding of the subcritical transition in boundary layer flows is quite poor as it involves complex non-linear phenomena. In the present mainly experimental study on the transition in a flat-plate boundary layer, we try to realize the flow-stages, similar to the so-called spike-stages observed by the present investigators in the ribbon-induced transition in plane Poiseuille flow, at the leading edge of the plate by means of acoustic excitation.
We found that the flow can develop wall turbulence structures below the displacement thickness Reynolds number R = 500 when the forcing is strong enough. In this case, the flow separates at the leading edge to form the so-called bubble with intense thin shear layer. The bubble shear layer rapidly develops into three-dimensional hairpin-shaped eddies so that we can observe spike-stages such as 1-spike and 2-spike stages noted above. In the case of 2-spike flow, wall shear layer appear in the low-speed region associated with the leading-edge generated hairpin eddies and it eventually develops into hairpin eddies, which we call the wall hairpin eddies. With the passage of such wall hairpin eddies, the low-speed wall streaks continue to appear and so do the assocated wall shear layers, which evolve into new wall hairpin eddied. The process of regeneration continues downstream to lead to the subcritical transition.
Thus, it is concluded that the successive generation or regeneration of wall hairpin eddies is the key event which sustains the wall turbulence.

Report

(3 results)
  • 1988 Annual Research Report   Final Research Report Summary
  • 1987 Annual Research Report
  • Research Products

    (19 results)

All Other

All Publications (19 results)

  • [Publications] M.Asai: Bulletin of Univ.Osaka Prefecture,Series A. 36. 99-107 (1987)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1988 Final Research Report Summary
  • [Publications] M.Nishioka: Journal of Fluid Mechanics. 190. 113-119 (1988)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1988 Final Research Report Summary
  • [Publications] 浅井雅人: 第20回乱流シンポジウム講演論文集 日本流体力学会誌「ながれ」別冊. 7. 113-118 (1988)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1988 Final Research Report Summary
  • [Publications] 西岡通男: 日本流体力学会誌「ながれ」. 7. 336-351 (1988)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1988 Final Research Report Summary
  • [Publications] 西岡通男: 日本航空宇宙学会誌. 37. 61-69 (1989)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1988 Final Research Report Summary
  • [Publications] M.Asai: Laminar-Turbulent Transition.

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1988 Final Research Report Summary
  • [Publications] Masahito Asai: "A Numerical Method for Generating Tollmien-Schlichting Waves" Bulletin of the University of Osaka Prefecture. 36. 99-107 (1987)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1988 Final Research Report Summary
  • [Publications] Michio Nishioka: "A New Approximate Expression for the Response of a Hot-Wire Anemometer" Journal of Fluid Mechanics. 190. 113-119 (1988)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1988 Final Research Report Summary
  • [Publications] Masahito Asai: "Response of Leading-Edge Separated Bubble Flows to External Disturbances" Proc. 20th Turbulence Symposium, Journal of Japan Sosiety of Fluid Mechanics. 7. 113-118 (1988)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1988 Final Research Report Summary
  • [Publications] Michio Nishioka: "Randamization Process of Fluctuations in the Ribbon-Induced Transition of Plane Poiseuille Flow" Journal of Japan Sosiety of Fluid Mechanics. 7. 336-351 (1988)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1988 Final Research Report Summary
  • [Publications] Michio Nishioka: "Evolution of Tollmien-Schlichting Waves into Wall Turbulence" Journal of the Japan Society for Aeronautical and Space Sciences. 37. 61-69 (1989)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1988 Final Research Report Summary
  • [Publications] M.Asai: Bulletin of Univ.Osaka Prefecture,Series A. 36. 99-107 (1987)

    • Related Report
      1988 Annual Research Report
  • [Publications] M.Nishioka: Journal of Fluid Mechanics. 190. 113-119 (1988)

    • Related Report
      1988 Annual Research Report
  • [Publications] 浅井雅人: 第20回乱流シンポジウム講演論文集日本流体力学会誌「ながれ」別冊. 7. 113-118 (1988)

    • Related Report
      1988 Annual Research Report
  • [Publications] 西岡通男: 日本流体力学会誌「ながれ」. 7. 336-351 (1988)

    • Related Report
      1988 Annual Research Report
  • [Publications] 西岡通男: 日本航空宇宙学会誌. 37. 61-69 (1989)

    • Related Report
      1988 Annual Research Report
  • [Publications] M.Asai: Laminar-Turbulent Transition.

    • Related Report
      1988 Annual Research Report
  • [Publications] 西岡通男, 浅井雅人, 古本伸一: 日本航空宇宙学会誌.

    • Related Report
      1987 Annual Research Report
  • [Publications] 西岡通男, 浅井雅人, 吉田信治: 日本航空宇宙学会誌.

    • Related Report
      1987 Annual Research Report

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Published: 1987-04-01   Modified: 2016-04-21  

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