TRANSPIRATION COOLING WITH CHEMICAL REACTIONS,

Transpiration coolant requirements are examined for gassolid systems in which the thermal effects of chemical reactions must be taken into account. For example, a coolant may undergo phase change and chemical decomposition in passage through the wall itself. This would alter the effective heat absorption capability and the mean molecular weight of the effluent gas. Further chemical reaction may occur when the coolant vapors or decomposition products mix with the hot gases in the boundary layer. In general, both processes will influence the amount of coolant required to maintain a prescribed surface temperature, and therefore significantly alter the relative merits of possible coolants. As such, thermochemical effects are of great practical interest. Simple computational techniques and numerical examples are given herein, together with a discussion of several factors governing the rates of these chemical reactions. Author