Film Cooling of a Blunt Body in a Supersonic High-Enthalpy Flow

During atmospheric reentry at hypersonic speed and during very-high-speed flight in the atmosphere, vehicles experience extremely high thermal loads for relatively long time. To handle this problem, classical thermal protection materials may need to be replaced with lightweight actively cooled components. This work investigates experimental film cooling of a blunt body in a supersonic high-enthalpy flow. The coolant injected from the center of the blunt body surface against the freestream generates a thin, cool insulating layer, yielding a thickening of the boundary layer, thus reducing the temperature gradient and the resulting heat flux to the surface. Experiments were performed in the Aerothermodynamics Laboratory of the Technion–Israel Institute of Technology, where a 5 MW arc plasma tunnel enables simulation of high-enthalpy flows. Two models (with and without injection) were exposed to a Mach 2.2 freestream with a total enthalpy of . Nitrogen and helium were used as coolants gases. A parametric study shows the influence of coolant physical properties and mass flow rate on the characteristics of the flow surrounding the model and on the resulting temperature reduction at different locations on the test model.