VORTEX DISTORTION DURING VORTEX-SURFACE INTERACTION IN A MACH-3 STREAM

An experimental study has been conducted in a Mach 3 wind tunnel to in vestigate the behavior of supersonic vortices as they interact with a wedge surface placed in their passage. The experimental setup was arra nged so that interactions resulted in a close encounter of the vortex core and the wedge leading edge. Spark shadow photographs of the flowf ield along with pressure measurements on the wedge surface were used t o study the interaction problem. Is their most organized form, distort ion of streamwise vortices upon interacting with the wedge was found t o result in formation of symmetric detached shock fronts far upstream of the wedge leading edge followed by an apparent slip surface separat ing a subsonic region from a supersonic zone. Interaction experiments leading to substantial changes in the structure of vortices revealed t hat the supersonic vortex distortion has strong resemblances to the in compressible ''B-breakdown'' reported in the literature. Experimental results also indicate that the interaction strongly depends on the vor tex strength and vortex proximity to the wedge leading edge, and the g enerated flowfield was found to be highly unsteady. Interaction of con centrated streamwise vortices with the oblique shock formed over the w edge surface resulted in formation of a locally three-dimensional shoc k wave with a limited subsonic region downstream of the shock.