Experimental studies of separated flows at hypersonic speeds. II - Two-dimensional wedge separated flow studies.

Abstract

This paper describes an experimental study of the flow patterns and distribution of heat transfer developed in regions of adverse pressure gradient and separated flow over two-dimensional models in a Mach 10 airflow at a freestream Reynolds number of 1.35 X 10/in. Schlieren photographs and heat-transfer distributions were obtained in regions of adverse pressure gradient and moderately separated flow, induced by both forward-facing wedges and externally generated shock, to detect the difference between a flow in which the boundary layer had been merely thickened by an adverse pressure gradient and one in which there was a region of reverse flow. A separation criterion, based on a distinctive change in heat-transfer profile at the beginning of the interaction, is suggested to distinguish between unseparated and separated flows. A study was made to determine the effect of reattachment angle, boundary-layer thickness at separation, and downstream expansion on the heat transfer generated in the reattachment region on the wedge of a flat-plate-wedge model. The reattachment heat-transfer rates were found to be strongly dependent on reattachment angle; whereas for the configurations tested, there was little influence of the boundary-layer thickness at separation or downstream expansion. The measurements were correlated in terms of the viscous interaction parameters MC# and \R and also compared with calculations based on simple models for the separated flowfield.