2002 Fiscal Year Final Research Report Summary
Turbulent Model of Coherent Structures in a Transitional Boundary Layer
| Project/Area Number |
13650178
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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 | Toyohashi University of Technology |
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Principal Investigator |
MAKITA Hideharu Toyohashi University of Technology, Dept.of Engineering, Professor, 工学部, 教授 (40135413)
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| Project Period (FY) |
2001 – 2002
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| Keywords | Boundary Layer / Transition / Turbulent Spots / Horseshoe Vortex / Turbulent Bulge / Flow Control / Flow Visualization / Conditional Measurement |
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| Research Abstract |
In order to experimentally study interaction phenomena between turbulent spots in a laminar boundary layer or horseshoe vortices in a turbulent boundary layer, a pair of turbulent spots or horseshoe vortices was artificially developed in each boundary layer. Then, a synthetic transitional boundary layer was generated by inducing many turbulent spots to clarify the effects of their interaction process on the structure of the boundary layer. To observe the vortex structure, coherent velocity and vorticity components were obtained trough conditional hot-wire measurement.
(1)The longitudinal vortex at each inside wingtip comes into contact, as the two spots begin to merge. Mutual interaction between them generates a strong upwash and give birth to a strong velocity-defect region in the upper merged region.
(2)The spanwise vortices constitute the heads of large-scale horseshoe vortices connecting the longitudinal vortices beneath and may grow into turbulent bulges in the downstream turbulent boundary layer. As the array of turbulent spots grows up into a turbulent boundary layer, its periodical structure survives still around the boundary layer's outer edge.
(3)The merged horseshoe vortices grew to be a single larger horseshoe vortex in the downstream region, when two horseshoe vortices were induced simultaneously.
(4)When the two horseshoe vortices were induced with time delay of 20msec, they are not connected with each other and apparently, their inside legs were not separated from each horseshoe vortex.
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Research Products
(10 results)
