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Turbulence development in a non-equilibrium turbulent boundary layer with mild adverse pressure gradient

Published online by Cambridge University Press:  27 May 2005

C. D. AUBERTINE
Affiliation:
Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
J. K. EATON
Affiliation:
Department of Mechanical Engineering, Stanford University, Stanford, CA, USA

Abstract

High-resolution laser-Doppler anemometer measurements were acquired in a two-dimensional turbulent boundary layer over a $4^\circ$ ramp. The goals were to provide a detailed data set for an adverse pressure gradient boundary layer far from separation and to examine near-wall behaviour of the Reynolds stresses as compared to flat-plate boundary layers. The flow develops over a flat plate, reaching a momentum thickness Reynolds number of 3350 at an upstream reference location. The boundary layer is then subjected to a varying pressure gradient along the length of the ramp and partially redevelops on a downstream flat plate. Mean velocity measurements show a log law region in all velocity profiles, but the outer layer does not collapse in deficit coordinates indicating that the boundary layer is not in equilibrium. Measurements of non-dimensional stress ratios and quadrant analysis of the two-component data indicate relatively small changes to the turbulence structure. However, the streamwise normal stress has an extended outer layer plateau, and the shear stress and wall-normal stress have outer layer peaks. Near the wall, the streamwise normal stress and shear stress collapse with flat-plate data using standard scaling, but the wall normal stress is substantially larger than flat-plate cases.

Type
Papers
Copyright
© 2005 Cambridge University Press

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