The influence of large scale roughness on a turbulent hypersonic boundary layer approaching a compression corner

The influence of large scale regular surface roughness on a Mach 5 turbulent boundary layer approaching a compression corner was investigated on axisymmetric wind tunnel models. Roughnesses were of saw tooth and cavity shape with typical dimensions up to a full boundary layer thickness. The effects of roughness on flow parameters differed significantly for each measured quantity. Velocity profiles were found to be less full and skin friction was reduced downstream of the roughness. Surface heat flux was increased for a short distance. Surface pressures remained unchanged. Little influence was noted on the flow in the compression corner. Upstream influence was increased in some cases but no large scale separation was observed. Rough nesses of saw tooth shape were found to cause greater disturbance to the flow than square cavities