Heat Transfer and Aero-Optical Effects of Film Cooling in Hypersonic Flow

Heat transfer and aero-optical effects over an optical window in hypersonic flow with supersonic film cooling are investigated using delayed detached-eddy simulations. Wall heat flux exhibits zone-dependent characteristics. In the corner regions, corner vortices enhance heat transfer, reducing cooling effectiveness to 30% rapidly. In the central quasi-two-dimensional region, turbulent mixing causes a segmented, increasingly rapid drop in effectiveness to 70%. Conversely, aero-optical effects subside into a relatively stable plateau following severe distortion. Spectral and dynamic mode decomposition analyses reveal the underlying unsteady mechanisms. In the potential-core region, a high-frequency mode ([Formula: see text]) dominated by Kelvin–Helmholtz vortex shedding drives severe aero-optical jitter. In the subsequent wall-jet region, a low-frequency mode ([Formula: see text]) of large-scale streaks becomes prominent as crossflow effects delay streak breakdown. However, it induces neither severe aero-optical distortions nor a rapid increase in wall heat flux. Further downstream, in the boundary-layer region, medium-frequency modes ([Formula: see text]) associated with turbulent streamwise vortices accelerate heat transport from the mixing layer to the wall, rapidly increasing the local heat flux. These findings support an optimized optical layout positioned within the central wall-jet region to mitigate high- and medium-frequency optical distortions and rapid wall-heat-flux augmentation.