Large-Eddy Simulation of Supersonic Film Cooling at Finite Pressure Gradients

Large-eddy simulations are performed to analyze film cooling in supersonic combustion ramjets (Scramjets). The transonic film cooling flow is injected through a slot parallel to a Ma = 2.44 main stream with a fully turbulent boundary layer. The injection Mach number is Mai = 1.2 and adiabatic wall conditions are imposed. The cooling effectiveness is investigated for adverse and favorable pressure gradients which are imposed onto the potential core region right downstream of the slot. The numerical results are in good agreement with the measured adiabatic cooling effectiveness. The turbulent mixing process of the injected cooling flow shows high turbulence levels just downstream of the lip and slowly increasing turbulence levels in the cooling flow. At a favorable pressure gradient, the adiabatic film effectiveness downstream of the potential core region is significantly increased by approximately 50% compared to the film cooling flow without a pressure gradient, whereas the adverse pressure gradient leads to a reduction of adiabatic film effectiveness by 30%.