Large-Eddy Simulation of Shock/Cooling-Film Interaction

The interaction of shock waves with supersonic cooling films is analyzed using large-eddy simulations. The laminar cooling flow is injected at Mach 1.2 through a slot into a fully turbulent boundary layer at Mach 2.44. For this injection condition, three configurations are investigated. A zero-pressure-gradient flow is compared with two configurations where shock waves are generated by a flow deflection of 5 deg. The shock waves impinge onto the cooling flow at two positions downstream of the slot. When the impingement is located within the potential-core region of the cooling flow, the adiabatic cooling effectiveness is reduced by as much as 36% compared to the zero-pressure-gradient configuration because the shock/cooling-film interaction excites a transition of the laminar slot boundary layer. Additionally, turbulence levels are significantly increased by the shock wave, and high temperature fluctuations occur. When the shock-wave impingement is located further downstream of the slot, there is an even steeper slope in cooling effectiveness in the streamwise direction. That is, the slope is 37 and 21% steeper compared to the zero-pressure gradient and the potential-core cases. The turbulent Prandtl number varied over the flow region of the shock/cooling-film interaction from 0.5 to 2.