Numerical Simulation of Transpiration Cooling with a Two-Dimensional Substructure

This paper presents a numerical model which assesses the coupled effect when transpiration cooling is applied to the external skin of a thermal protection system and the substructure of a high speed flight vehicle. The PIRATE transpiration cooling code has been extended and validated to account for quasi-two-dimensional lateral conduction effects allowing for analysis of more complex geometries. This enables very fast calculations of the two dimensional transient temperature response of a transpiration cooled thermal protection system, ideally suitable for large scale systems studies. To solve for the coupled transpiration cooled material and two-dimensional substructure, PIRATE has been coupled with the commercial finite element package COMSOL. This enables modelling of the longer term thermal effects of the integrated heat load over a flight trajectory. Transpiration cooling has been applied to a simplified blunt body model with an aluminium substructure. Results for the substructure temperature history for the Space Shuttle trajectory are obtained showing that transpiration cooling can lead to a 40% reduction in peak substructure temperature as well as a reduction in thermal stresses near the stagnation point