| Autor: |
Hans-Hermann Fernholz, André Huppertz |
| Rok vydání: |
2002 |
| Předmět: |
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| Zdroj: |
European Journal of Mechanics - B/Fluids. 21:429-446 |
| ISSN: |
0997-7546 |
| DOI: |
10.1016/s0997-7546(02)01190-1 |
| Popis: |
The aim of this experimental investigation has been to reduce the length of the three-dimensional separation region downstream of a swept surface-mounted fence by time-periodic blowing and suction generated by loudspeakers along a spanwise slot either upstream of or at the tip of a fence. The sweep angles were 0° and 20° and the Reynolds number Reh≡UNh/ν=5330. Two flow phenomena were used for the manipulation of the shear layer and the reduction of the separation length: • the coherent structures of the separated shear layer (Kelvin–Helmholtz instability) were influenced to increase entrainment by single and bimodal forcing at the tip of the fence. Here the effective disturbance amplitude could be small (e.g., A=O(0.1UN)); • the corner flow upstream of the fence was manipulated by the upstream actuator-slot so that a starting-type vortex roll formed at the tip of the fence, increased entrainment just downstream of the fence and reduced the separation length. Here the effective disturbance amplitude was large (e.g., A=O(UN)). Reattachment could be reduced at most by about 35% of the non-manipulated reattachment length. Measurements in the flow field were performed by LDA and DPIV and on the wall by pulsed-wire anemometry (PWA). |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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Full Text from ScienceDirect