Investigation of Combined Transpiration and Opposing Jet Cooling of Sintered Metal Porous Struts

Struts are used to inject fuel into the supersonic mainstream of scramjet combustion chambers. The leading edge of the strut experiences the maximum temperature due to tremendous aerodynamic heating. This study describes a combined transpiration and opposing jet cooling system for sintered metal porous struts with a jet flowing out of a micro-slit along the stagnation point line against the incoming flow with methane as the coolant. The combined cooling method for the struts is then compared to cooling by the standard transpiration method. The influences of different slit widths and coolant injection conditions on the strut cooling are numerically investigated. The results show that the combined cooling method significantly reduces the maximum strut temperature. The maximum strut temperature decreases but the coolant consumption increases with increasing micro-slit width. Increasing the micro-slit width more effectively balances the increased cooling effectiveness with the increased coolant flow than just increasing the coolant injection pressure. Coolant injection with non-uniform pressures with higher pressure in the front cavity and lower pressure in the back cavity more effectively enhances the cooling effectiveness and reduces the thermal gradient.