Experiments in Unsteady Forcing of Mach 2 Shock Wave/Boundary Layer Interactions

Abstract

An experimental study was conducted to study the effects of unsteady upstream forcing on Mach 2 shock wave/boundary layer interactions. Two separate experiments were perfor med. In the first experiment, phase -locked wide -field PIV was used to study how pulsed vortex generator jets affected the interaction generated by a circular cylinder. The jets were pitched at an angle of 60o and skewed at an angle of 90o, and operated eit her continuously or at a frequency of 100 Hz. The jets were shown to increase the velocity in the lower boundary layer, making it more resistant to separation. Additionally, the scale of the interaction was changed as the primary horseshoe vortex became sm aller while the secondary cylinder -root vortex became larger. In the second experiment wide -field PIV and planar flow visualization were used to study the effects of counter -rotating -vane vortex generators at a frequency of 50 Hz on a 20 o unswept ramp int eraction. The vortex generators were shown to energize the upstream boundary layer and had a significant effect on the location and strength of the separation shock. The vortex generators also showed a significant decrease in size of the separation flow scale .