| Project/Area Number |
17560140
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Fluid engineering
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| Research Institution | Shinshu University |
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Principal Investigator |
MATSUSBARA Masaharu Shinshu University, Fuculity of Engineering, Associate Professor (10324229)
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| Co-Investigator(Kenkyū-buntansha) |
YOSHINO Masato Shinshu University, Fuculity of Engineering, Associate Professor (00324228)
SASAKI Atsushi Shinshu University, Fuculity of Engineering, Research Associate (80362101)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,650,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥150,000)
Fiscal Year 2007: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2006: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2005: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | transition / boundary layer / turbulence grid / free stream turbulence / flow visualization / 流れの可視化 |
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| Research Abstract |
This research has been focused on revealing the transition process in a flat plate boundary layer subjected to a weak free stream turbulence by flow visualization and hot-wire measurements. A weak free stream turbulence was generated by a turbulence grid mounted upstream of the contraction. The flow visualization clearly displayed a transition scenario in which a local two-dimensional wave packet rapidly forms a A shape structure and then breaks down to turbulence, resulting in the generation of a turbulent spot. Quantitative measurements performed by using a hot-wire anemometer also confirmed the existence of local TollmierrSchlichting waves that agreed with the parallel linear theory in terms of their frequency, phase velocity, and the wall-normal distribution of band-pass-filtered fluctuations. For comparison, a boundary layer subjected to a moderate-intensity free stream turbulence was investigated. This investigation showed that streaky structures play an important role in the boundary layer transition, as shown by Matsubara et al. [J. Fluid Mech, 430, (2001), 149-168. ] A drastic change occurred in the transition process and this change could be sensitively determined by employing the intensity and/or spectra of the free streamturbulence.
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