Influence on the Hypersonic Boundary-Layer Flow

For aerospace or hypersonic cruise vehicle the state of the boundary layer is of great importance because for turbulent boundary layers, the thermal loads and skin friction are higher than in laminar boundary layers. Therefore , knowledge of cooling features and laminar-turbulent transition is necessary for the design of the thermal protection system (TPS). Different strategies are used to reduce the thermal loads of hypervelocity vehicles, e.g. radiation, ablation, transpiration or effusion cooling. Direct numerical simulations (DNS) are carried out to investigate the effect of effusion cooling by blowing through spanwise slits and discrete holes in a laminar flat-plate boundary layer at various Mach numbers. The numerical method and boundary conditions are described in section 9.2. A comparison with experimental data of project RESPACE-A7 for a Mach-2.67 boundary layer with a cool wall and a spanwise slit is presented in section 9.3.1. In section 9.3.2, a comparison of various effusion-cooling configurations (slits and holes) and laminar instability investigations are made for an adiabatic Mach-6 boundary layer. Results for effusion cooling at flight conditions are shown in section 9.3.4, and section 9.4 summarizes the results.