Experimental investigation of combined transpiration and film cooling for sintered metal porous struts

A combined transpiration and film cooling method was evaluated experimentally for protecting struts made of sintered stainless steel porous media with film holes on the leading edge in a supersonic wind tunnel. The combined cooling results were compared to standard transpiration cooling of the strut. Schlieren figures show that the film cooling and transpiration cooling had little effect on the flow field stability and the shock wave profiles around the struts for the present conditions. Standard transpiration cooling can protect most of the strut but cannot effectively cool the leading edge even with increased coolant injection pressures. The combined film and transpiration cooling effectively cools both the leading edge and other parts of the strut. Non-uniform coolant injection with higher injection pressures in the front cavity and lower injection pressures in the back cavity more effectively utilized the limited coolant flow. The average cooling efficiency of the front part of the strut increased from 25.7% for standard transpiration cooling to 37.9% for combined transpiration and film cooling with the same coolant consumption using the optimal non-uniform coolant flow distribution.