Analysis of the near-wall flow field in shock-cooling-film interaction for varying shock impingement positions

Abstract

A supersonic film-cooling configuration with shock interaction is investigated experimentally by means of high-speed particleimage velocimetry. A laminar cooling film is injected at an injection Mach number of Ma i = 1.8 beneath a turbulent boundary layer at a freestream Mach number of Ma ∞ = 2.45. A flow deflection of β = 8 deg generates a shock wave which impinges upon the cooling film at different streamwise positions in the potential-core or the wall-jet region. The influence of the impingement position of the incident shock on the cooling film is analyzed by time-averaged velocity fields and Reynolds shear stress distributions. The results show severe shock-induced flow separation. Shock impingement in the wall-jet region leads to a significantly larger separation bubble compared to shock impingement in the potential-core region. The shock interaction causes intense turbulent mixing between the outer flow and the cooling film downstream of the impingement position. The Reynolds shear stress is increased by a factor of 6 and by a factor of 8 for shock impingement in the potential-core region and in the wall-jet region compared the undisturbed reference case.