Measurements Of A Three Dimensional Shock Boundary Layer Interaction

A series of measurements were taken of the shock-boundary layer interaction (SBLI) in a Mach 2.1 continuously operated wind tunnel. The SBLI was generated by a small (~1.1mm tall) 20° wedge located on the top wall, and data were taken both in the region near the compression wedge and in the area where this shock impinged on the bottom wall. PIV was the primary measurement tool in both locations, though pressure data were also acquired near the compression wedge. Data were acquired at 4 spanwise locations to study the three-dimensionality of the flow. Both interactions were found to be highly 3-D, with a stronger interaction observed near the channel centerline. Evidence of a corner vortical structure in the compression corner was observed, and substantiated by CFD. Intermittent flow reversal was seen in the reflected shock interaction near the channel centerline, though not in the corners. The data suggest the presence of vortical structures generated near the channel centerline and pushed towards the sidewalls. Following the characterization of the base case, a Monte Carlo experiment was performed in which geometric perturbations were installed along the bottom wall of the wind tunnel and their effect on the flow was studied. The Monte Carlo device was designed and installed at the location predicted to be most sensitive by CFD. The majority of the locations initially tested displayed minimal sensitivity, with only the largest and most upstream quasi-2D cases showing significant effects on the flow at the corner. The perturbation device was redesigned and moved upstream, and additional quasi-2D cases were tested. It was found that some configurations accelerated the flow and strengthened the primary shock, while others slowed the flow and weakened the shock. Overall, the flow was observed to be very sensitive to some perturbations, but only to those located within a limited range of streamwise positions, and with a wide variety of system responses possible.