Roughness Effects on the Crossflow Instability on the HIFiRE-5 Geometry

Experiments were performed in the Boeing/AFOSR Mach 6 Quiet Tunnel at Purdue University using arrays of roughness elements to attempt to control the crossflow instability on the HIFiRE-5 geometry. Viscous CFD and instability analyses using LASTRAC were used to design the roughness arrays. A vortex-generator style of roughness was used to attempt to more directly inject co-rotating vortices into the boundary layer, instead of the horseshoe vortices created by cylindrical roughness elements. The roughness arrays used show influence on the strength of the crossflow vortices, making them stronger and weaker as expected, though with inconsistencies. Control of the vortex spacing and positioning was not demonstrated.