The flow produced by interaction of a turbulent boundary layer with a normal shock wave of strength sufficient to cause separation

Abstract

Summary. The nature of normal-shock and turbulent-boundary-layer interaction is described on the basis of an experiment involving two-dimensional flow, at M = 1.47, over a flat plate. Special attention is paid to the flow development downstream of separation. Conditions governing reattachment are observed and the nature of the eddy-flow bubble is shown. Compatibility requirements between the viscous and non-viscous flows are described. In the viscous layer itself the flow is shown to undergo successiveiy the three processes of shock compression, displacement and rehabilitation. For an interaction in which no mainstream constraints are applied, separation occurs at a point two boundary-layer thicknesses downstream of the start of interaction, and reattachment at 12 thicknesses. Rehabilitation, however, is still incomplete at 50 thicknesses. Velocity profiles are examined in relation to the Coles wake hypothesis. Over the greater part of the flow this hypothesis is found to hold true. It does not hold in the immediate vicinity of the shock wave or in other regions of strong pressure gradient. An empirical extension is suggested to take account of the variations observed.