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The structure of a shear layer bounding a separation region. Part 2. Effects of free-stream turbulence

Published online by Cambridge University Press:  21 April 2006

I. P. Castro  and
A. Haque
I. P. Castro
Affiliation:
Department of Mechanical Engineering, University of Surrey, Guildford, Surrey, GU2 5XH, UK
A. Haque
Affiliation:
Department of Chemical Engineering, Imperial College, London, SW7 2AZ, UK
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Abstract

Detailed measurements throughout the separated region behind a flat plate placed normal to a turbulent stream are reported. A long, central, downstream splitter plate prevented vortex shedding and led to a relatively extensive reversed flow region. Mean flow and turbulence data are compared with results obtained in the (nominal) absence of free-stream turbulence, and attention is concentrated on the changes in the shear-layer structure resulting from the different nature of the upstream flow.

Many aspects of the results confirm those obtained recently by other workers. Free-stream turbulence enhances shear-layer entrainment rates, reduces the distance to reattachment and modifies the relatively low-frequency ‘flapping’ motion of the shear layer. In addition, however, extensive use of pulsed wire anemometry has allowed detailed measurements of the turbulence structure throughout the flow and it is shown that this is also modified significantly by the stream turbulence.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 192 , July 1988 , pp. 577 - 595
Copyright
© 1988 Cambridge University Press

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