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The effects of turbulence on a separated and reattaching flow

Published online by Cambridge University Press:  21 April 2006

Yasuharu Nakamura  and
Shigehira Ozono
Yasuharu Nakamura
Affiliation:
Research Institute for Applied Mechanics, Kyushu University, Kasuga 816, Japan
Shigehira Ozono
Affiliation:
Research Institute for Applied Mechanics, Kyushu University, Kasuga 816, Japan
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Abstract

The effect of free-stream turbulence on the mean pressure distribution along the separation bubble formed on a flat plate with rectangular leading-edge geometry is investigated experimentally in a wind tunnel using turbulence-producing grids. Emphasis is placed on finding the effect of turbulence scale. The ratio of turbulence scale to plate thickness investigated was about 0.5 to 24 for two values of turbulence intensity of about 7 and 11%. The Reynolds number based on plate thickness was approximately (1.4–4.2) × 104.

It is found that the main effect of free-stream turbulence is to shorten the separation bubble. It is progressively shortened with increasing turbulence intensity. The mean pressure distribution along the shortened separation bubble is insensitive to changing turbulence scale up to a scale ratio of about 2. With further increase in the scale ratio it asymptotes towards the smooth-flow distribution. There is no trace of interaction between turbulence and vortex shedding (the impinging-shear-layer instability) in the mean pressure distribution.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 178 , May 1987 , pp. 477 - 490
Copyright
© 1987 Cambridge University Press

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