Experimental study of supersonic turbulent corner flow evolution in a low aspect ratio rectangular channel

Abstract

Supersonic turbulent flows in a rectangular duct are characterized by secondary flows in each of the four corners of the duct. These secondary flows comprise of two counter rotating vortices forcing the fluid towards the corner. The vortices are developed as a result of the Reynolds stress gradients which exist in each of the corners. Previous studies 1,2 have primarily used intrusive techniques such as Preston/pitot tubes and hot wire in order to study the secondary flows in the corners. However use of these techniques would substantially modify the flow in low aspect ratio rectangular channels. Thus, there is a need for non-intrusive measurements to study the evolution of corner vortices in such flows. In this study we present the experimental results of stereo particle image velocimetry conducted on a Mach 2.75 flow in a low aspect ratio rectangular channel. Data is recorded at multiple cross-section planes and analyzed to study the formation of corner vortices and their effects on the structure of the mean flow field. Results show that the corner vortices are formed in the corner and then convect away from it. There is a significantly strong secondary flow associated with the corner vortices possibly causing open flow separation. The vortices significantly modify the local variation of the skin friction coefficient.