Transpiration cooling of hypersonic flow past a flat plate with porous injection

Transpiration-based cooling using porous layer is explored where the coolant is injected into the hypersonic cross-flow, providing a more uniform distribution of the coolant. Three-dimensional direct numerical simulations of flow past a at plate with a porous layer are conducted at M = 5. Conjugate heat flux boundary condition is used as compared to the simpler isothermal wall. The coolant is injected through a porous layer composed of a staggered (body-centered cubic) arrangement of spheres. Smaller pressure ratios resulting in relatively smaller blowing ratios are used, which are found to be more effective in the experiments. Also, to mimic turbulent conditions in the experiments, wall-bounded disturbances are introduced upstream of the porous layer such that reasonable mixing of coolant is allowed inside the hypersonic boundary layer. It is noted from the moderately high Reynolds number cases that the lowest blowing ratio results in more cooling immediately downstream of the porous layer, while the highest blowing ratio show higher effectiveness farther downstream.