Calculation of a gas-vapor-liquid heat screen on an adiabatic wall by means of h-d diagrams

The generation of an insulating layer by injecting gases into the boundary layer through openings in the wall is a promising method for the protection of walls against high-temperature gas flows. It is suggested here that the efficiency of this method can be further increased by injecting a two-phase coolant. This method would also provide an economic way to adjust the cooling system parameters over a wide range of thermal loads by changing the content of the liquid component in the coolant. It is shown how h-d diagrams (where h is the enthalpy and d is the mass content of the gas-vapor component) can be used to calculate the efficiency of the thermal protection of an adiabatic wall by a gas-vapor-liquid screen. The calculations show the advantages of the two-phase system over a single-phase system.