Numerical Study of the Evolution of Disturbances Generated by Roughness Elements in a Supersonic Boundary Layer on a Blunted Cone

Results of direct numerical simulations of the roughness-induced development of instability and transition to turbulence in a supersonic boundary layer on a blunted cone for the free-stream Mach number M_∞ = 5.95 are presented. The flow parameters and model geometry are consistent with the conditions of the experiments performed in the study. The following roughness types are considered: random distributed roughness, isolated roughness elements of different shapes, and a group of regularly arranged roughness elements. The processes of the instability development and transition for different roughness types are compared, and possible mechanisms of the roughness influence on the stability of boundary layers on blunt bodies are discussed.