Interaction of a Laminar Hypersonic Boundary Layer with a Corner Expansion Wave

Abstract

T paper describes the application of a quantitative space and time resolved schlieren system to measure density gradients in the region of interaction of a hypersonic laminar boundary layer with a corner expansion wave. Flowfield properties are inferred and compared with up-to-date theoretical results. In spite of many published attempts, the problem of calculating the flow of a supersonic or hypersonic boundary layer over an expansion corner has not really been satisfactorily solved. These analyses have invariably used simplifying assumptions which have resulted in omission of important physical parts of the problem, which is complex as it includes upstream influence and centrifugal effects, transverse pressure gradients in the boundary layer, and boundary-layer expansion wave interaction. As part of a theoretical and experimental program on this problem at the Institute for Aerospace Studies (UTIAS) Lo and Sullivan' reported an analysis which attempted to give a complete picture. The calculations, which used an integral technique, are related to the classical von Karman-Polhausen method. By using the viscous-inviscid equations throughout the entire regime of interest, significant centrifugal effects were shown to occur in a region which could extend far downstream of the corner. Details of the skin-friction and heat-transfer peaks were obtained, and the calculations also indicated the presence of a weak shock wave immediately downstream of the corner. Comparatively little experimental work has been done on the laminar hypersonic boundary-layer and corner expansion flow problem. This is mainly due to the difficulty encountered when relevant data is sought, particularly since only flowfield information can verify the presence of some of the more important physical effects.