A New Approach of Using Porous Bleed Boundary Conditions - Application of Local Porosity

Porous bleed systems are widely used to mitigate the shock-induced boundary layer separation, e.g., in supersonic air intakes. However, the complex geometry makes simulations expensive and motivates the application of suitable models. Existing models are based on applying a continuous blowing/suction boundary condition (continuous porosity) along the porous plate, leading to an overestimation of the boundary layer thinning. The new method using distributed suction by a local porosity is applied on a Mach 1.6 supersonic flow and improves the prediction of the effect on the boundary layer significantly. In contrast to the existing methods, the wall shear stress is not overestimated, and the boundary layer profiles downstream of the bleed region are better reproduced. Moreover, all expansion fans and barrier shocks caused by the bleed holes are captured.