Laminar Turbulent Transition in a Boundary Layer Subjected to Weak Free Stream Turbulence
For revealing the transition process in a flat plate boundary layer subjected to a weak free stream turbulence, flow visualization and hot-wire measurements were performed. A weak free stream turbulence was generated by a turbulence grid mounted upstream of the contraction. The flow visualization cl...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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The Japan Society of Mechanical Engineers
2008-02-01
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| Series: | Journal of Fluid Science and Technology |
| Subjects: | |
| Online Access: | https://www.jstage.jst.go.jp/article/jfst/3/1/3_1_56/_pdf/-char/en |
| _version_ | 1798022357727576064 |
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| author | Toshiaki KENCHI Masaharu MATSUBARA Toshihiko IKEDA |
| author_facet | Toshiaki KENCHI Masaharu MATSUBARA Toshihiko IKEDA |
| author_sort | Toshiaki KENCHI |
| collection | DOAJ |
| description | For revealing the transition process in a flat plate boundary layer subjected to a weak free stream turbulence, flow visualization and hot-wire measurements were performed. 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 Λ 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 Tollmien-Schlichting 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 stream turbulence. |
| first_indexed | 2024-04-11T17:28:36Z |
| format | Article |
| id | doaj.art-22ebbfc48a144c7189d76529087d6570 |
| institution | Directory Open Access Journal |
| issn | 1880-5558 |
| language | English |
| last_indexed | 2024-04-11T17:28:36Z |
| publishDate | 2008-02-01 |
| publisher | The Japan Society of Mechanical Engineers |
| record_format | Article |
| series | Journal of Fluid Science and Technology |
| spelling | doaj.art-22ebbfc48a144c7189d76529087d65702022-12-22T04:12:11ZengThe Japan Society of Mechanical EngineersJournal of Fluid Science and Technology1880-55582008-02-0131566710.1299/jfst.3.56jfstLaminar Turbulent Transition in a Boundary Layer Subjected to Weak Free Stream TurbulenceToshiaki KENCHI0Masaharu MATSUBARA1Toshihiko IKEDA2Department of Mechanical Systems Engineering, Shinshu UniversityDepartment of Mechanical Systems Engineering, Shinshu UniversityDepartment of Environmental Science and Technology, Shinshu UniversityFor revealing the transition process in a flat plate boundary layer subjected to a weak free stream turbulence, flow visualization and hot-wire measurements were performed. 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 Λ 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 Tollmien-Schlichting 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 stream turbulence.https://www.jstage.jst.go.jp/article/jfst/3/1/3_1_56/_pdf/-char/entransitionstabilityboundary layerfree stream turbulencetollmien-schlichting wavewave packet |
| spellingShingle | Toshiaki KENCHI Masaharu MATSUBARA Toshihiko IKEDA Laminar Turbulent Transition in a Boundary Layer Subjected to Weak Free Stream Turbulence Journal of Fluid Science and Technology transition stability boundary layer free stream turbulence tollmien-schlichting wave wave packet |
| title | Laminar Turbulent Transition in a Boundary Layer Subjected to Weak Free Stream Turbulence |
| title_full | Laminar Turbulent Transition in a Boundary Layer Subjected to Weak Free Stream Turbulence |
| title_fullStr | Laminar Turbulent Transition in a Boundary Layer Subjected to Weak Free Stream Turbulence |
| title_full_unstemmed | Laminar Turbulent Transition in a Boundary Layer Subjected to Weak Free Stream Turbulence |
| title_short | Laminar Turbulent Transition in a Boundary Layer Subjected to Weak Free Stream Turbulence |
| title_sort | laminar turbulent transition in a boundary layer subjected to weak free stream turbulence |
| topic | transition stability boundary layer free stream turbulence tollmien-schlichting wave wave packet |
| url | https://www.jstage.jst.go.jp/article/jfst/3/1/3_1_56/_pdf/-char/en |
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