Large-scale structure in a supersonic slot-injected flowfield

Abstract

Experimental results that show the existence of organized structures in a high-speed shear-layer flow are presented. Results were obtained using a parallel-array, dual-wire probe in a shear layer created by the mixing of tangential slot injection of supersonic air (Mj = 1.7) into a supersonic air mainstream (M = 3). The slot-injected flowfield was studied at three streamwise locations (X/H of 4, 10, 20). At each station, a region (1.5 > Y/H > 0.7) dominated by the upstream boundary layer resulted in structure angles on the order of 50 deg. Structures in this region appeared to be the remnants of structures observed in the upstream boundary layer. Integral length scale in this region was on the order of 3 mm or less and increased to 4 mm at X/H of 20. The effect of a shock impingement upon the shear layer was also investigated. The oblique shock had a nominal pressure ratio of 1.82. Structure angles and integral length scales appeared unaffected by the streamwise pressure gradient caused by the shock impingement.