Some Remarks on Shock Wave Turbulent Boundary-Layer Interaction at High Reynolds Number

Abstract

Extensive previous low Reynolds number experimental results of turbulent boundary-layer shock wave interaction developed trends not borne out by recent high Reynolds number results. The current study is the first phase of a detailed examination of the upstream propagation and incipient and developed separation caused by the flow in a corner over a range of Reynolds numbers from $10^7 $ to $10^9 $ based on length, $10^5 $ to $10^7 $ based on boundary-layer thickness. The experiments are being carried out to determine the correct extrapolation techniques to permit the use of low Reynolds number results at full scale conditions. Lack of resolution and a well-defined definition of experimentally determined separation are limitations of some of the past experimental studies, and the current investigation, using both two-dimensional and axially symmetric configurations at Mach $ \sim $, were designed to avoid these problems. The study clearly establishes the decrease in the extent of the upstream influence parameter with increasing Reynolds number, but there was always a small upstream influence ($ \sim $ boundary-layer thickness) even for the smallest imposed pressure ratios and highest Reynolds number. The variation of the upstream influence parameter increases with increasing imposed pressure ratio. There appears to be no significant variation of separation pressure ratio with variation of the Reynolds number over almost two decades, a trend in direct contradiction to previously published results on incipient separa-tion.