Numerical simulation of transpiration cooling for a high-speed vehicle with substructure

Abstract

This paper presents a numerical model that assesses the effect of applying transpiration cooling to both the outer wall and the substructure of a high-speed flight vehicle. The porous impulse response analysis for transpiration cooling evaluation (PIRATE) code has been extended and validated to account for quasi-two-dimensional lateral heat conduction effects, thereby 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 suitable for first-order systems studies. To solve for the transpiration-cooled outer wall and a two-dimensional solid substructure, PIRATE has been coupled with the commercial finite element package COMSOL. This enables modeling of the longer-duration thermal effects of the integrated heat load over a flight trajectory. Transpiration cooling using helium coolant has been applied to a wing leading-edge model with an aluminum substructure. Carbon–carbon ceramic composite and the ultra-high-temperature ceramic Zirconium diboride (ZrB2 ) are chosen as candidate materials. Results for the substructure temperature history for the space shuttle reentry trajectory are obtained, showing that transpiration cooling can lead to a 35% reduction in peak substructure temperature and a 65% reduction in thermal gradients.