Effect of coolant side heat transfer on transpiration cooling

A simple analysis is described addressing the effect of simultaneous cooling from the back side and from a transpiration flow through a porous wall. The analysis draws from existing approaches and uses simplified formulations for the boundary conditions. Therewith expressions for the non-thermal equilibrium situation and for the overall cooling effectiveness are derived. These parameters are used to estimate the effect of enhanced cooling side heat transfer in combination with transpiration flows. The analysis is extended to situations with two combined layers of porous transpiration cooled materials.