2016 Volume 64 Issue 4 Pages 244-252
Effects of upstream disturbances on a transverse jet into Mach 2 supersonic flow were investigated by using single-time two-point spatial correlations of fluctuating velocities in the flowfield. The fluctuating velocity was measured by stereoscopic PIV. We categorized the upstream disturbances into two factors: incoming boundary layer on the injection port and weak oblique shock wave impinging ahead of the injection port. The velocity fluctuations in the upstream boundary layer had a long positive correlation region in the boundary layer. This is the evidence that very large-scale motion (VLSM) existed in the boundary layer developed on our test section. The correlation region bifurcated into the regions along the bow shock wave and the outer jet boundary. The correlation length was 10-hold longer than the boundary layer thickness. Fluctuation of the weak shock wave was induced by VLSM developed on the opposite wall to the injection wall. The velocity fluctuation due to the weak shock wave also had a long positive correlation region along the oblique shock wave. However, it had no correlation with the jet.
