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Studies on By-Pass Transition of Boundary Layr

Research Project

Project/Area Number 08651090
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Aerospace engineering
Research InstitutionTokyo Metropolitan Institute of Technology

Principal Investigator

ASAI Masahito  Tokyo Metropolitan Institute of Technology, Faculty of Engineering, Associate Professor, 工学部, 助教授 (00117988)

Project Period (FY) 1996 – 1997
Project Status Completed (Fiscal Year 1997)
Budget Amount *help
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1997: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1996: ¥1,600,000 (Direct Cost: ¥1,600,000)
KeywordsFluid Mechanics / Boundary Layr / Laminar-Turbulent Transition / Turbulent Contamination / Hairpin Eddies / Critical Reynolds Number / 乱流 / 境界層
Research Abstract

In the present study, the so-called by-pass boundary-layr transition caused by high-intensity disturbances is examined experimentally. Our knowledge of the boundary-layr response to such high-intensity disturbances is crucial, for instance, for understanding the attachment-line contamination on a swept wing. In addition, it is expected that the results give much information on the mechanism of wall turbulence generation and the related critical flow condition.
The whole experiment is carried out in a wind tunnel with open jet type. A boundary-layr plate is set in the open test section. Well-controlled hairpin eddies is introduced in Blasius boundary layr at subcritical Reynolds numbers (for linear instability) through a small wall orifice. The results obtained are summarized below.
Local turbulent patch created by the orifice-generated hairpin vortices can develop only at Reynolds numbers above R_<rheta>=130 (based on the momentum thickness). In such low-Reynolds number transition, the l … More ateral growth of turbulent patch is very weak, i.e., the lateral spreading angle is less than 2 deg. With increasing the Reynolds number, the lateral spreading angle is rapidly increased towards the typical value (10 deg) at high Reynolds numbers. The dependency of the lateral spreading angle of turbulent patch on R_<rheta> is clearly demonstrated in the present experiment. It is also worth noting that the growth of turbulent patch is highly dependent on the intensity of initial hairpin vortices in this subcritical boundary-layr transition.
A key event observed is found to be successive growth of wall shear layrs (lifted up on low-speed streaks) with streamwise vortices into hairpin vortices, which is almost the same as the near-wall phenomena observed in the late stage of the ribbon-induced transition in plane Poiseille flow. Below the critical station (R_<rheta>=130), even if highly disturbed and once the wall streaks with streamwise vortices are created, they eventually decay downstream. Less

Report

(3 results)
  • 1997 Annual Research Report   Final Research Report Summary
  • 1996 Annual Research Report
  • Research Products

    (10 results)

All Other

All Publications (10 results)

  • [Publications] Masahito Asai: "Lateral Turbulent Contamination in Subcritical Boundary-Layer Transition" Memoirs of Tokyo Metropolitan Institute of Technology. 10. 109-115 (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Masahito Asai: "Development of Wall Turbulence Structure in Transitional Flows" Theoretical and Applied Mechanics 1996,Elsevier. 121-138 (1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Masahito Asai: "Three-Dimensional Growth of Tollmien-Schlichting Waves excited at Two Frequencies" Fluid Dynamics Research. 22. 215-230 (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Masahito Asai: "Three-dimensional growth of Tollmien-Schlichting waves excited at two frequencies." Fluid Dynamics Research. 22-4. 215-230 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Masahito Asai: "Development of wall turbulence structure in transitional flows." Theoretical and Applied Mechanics (eds.T.Tatsumi, E.Watanabe & T.Kambe), Elsevier. 121-138 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] Masahito Asai: "Lateral turbulent contamination in Blasius flow at low Reynolds numbers." Memoirs Tokyo Metropolitan Institute of Technology. 10. 109-115 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] M.Asai: "Three-Dimensional Growth of Tollmien-Schlichting Waves excited at Two Frequencies" Fluid Dynamics Research. 22・4. 215-230 (1998)

    • Related Report
      1997 Annual Research Report
  • [Publications] M.Asai: "Development of Wall Turbulence Structure in Transitional Flows" Theoretical and Applied Mechanics 1996,Elsevier. 121-138 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] M.Asai: "Development of Wall Turbulence Structure in Transitional Flows" ICTAM Kyoto 1996, Elsevier. (1997)

    • Related Report
      1996 Annual Research Report
  • [Publications] M.Asai: "Lateral Turbulent Contamination in Subcritical Boundary-Layer Transition" Memoirs of Tokyo Metropolitan Inst.Tech.10. 109-115 (1996)

    • Related Report
      1996 Annual Research Report

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Published: 1996-04-01   Modified: 2016-04-21  

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