Heat Balance of a Transpiration-Cooled Heat Shield

Abstract

HEATS is a layout tool for the determination of transient wall heat flux to a transpiration-cooled parallel flat plate under laminar or turbulent flow conditions. The method is based on heat balances between wall material, transpired coolant, and surrounding hot gas. It is introduced here with particular focus on a reentry mission. The investigation of transpiration cooling necessitates considering the entire flight trajectory. Because of long calculation times, computational fluid dynamics tools cannot be used. The calculation of wall temperatures of an entire trajectory with HEATS takes less than five minutes, which offers the possibility of sensitivity analyses, e.g., of coolant mass flow rate. The results presented within this paper are compared with cooling experiments under laminar flow and a computational fluid dynamics solution of one trajectory point for the second Sharp-Edge Flight Experiment trajectory for turbulent flow. The values compare well with deviations of the wall temperature below 10% and deviations of heat flux below 18%. The investigation of coolant mass flow rates by means of HEATS show that for the entire second Sharp-Edge Flight Experiment trajectory the transpiration-cooling experiment should be run with 0,1 g/s < m < 1 g/s.