Experimental Study on Combined Cooling Method for Porous Struts in Supersonic Flow

A combined transpiration and opposing jet cooling method was experimentally investigated for protecting porous struts with microslits in the leading edge. Schlieren images showed that this cooling method significantly affects the stability of the flow field and the profile of the detached shock wave. Three different states of flow fields were observed when increasing the coolant injection pressure of a strut having a 0.20 mm wide micro-slit. The detached bow shock was pushed away by the opposing jet; it then became unstable and even disappeared when the coolant injection pressure was increased. Combined transpiration and opposing jet cooling could effectively cool the entire strut, especially the leading edge. The leading edge cooling efficiency increased from 3.5% for the leading edge without a slit to 52.8% for the leading edge with a 0.20mm wide slit when the coolant injection pressure was 0.55 MPa. Moreover, combined transpiration and opposing jet cooling with nonuniform injection distribution made the strut temperature distribution more uniform and caused the maximum temperature to decrease compared to standard transpiration cooling.