Heat transfer in a multi-layered thermal protection system under aerodynamic heating

Future generation reusable re-entry vehicles must be capable of sustaining consistent repeated aero-thermal loads without damage or deterioration. This means that such structures should be able to withstand high temperatures engendered by aero-thermal re-entry fluxes due to the establishment of a hypersonic regime over the body. Thermal Protection Systems (TPS) are used to maintain a reusable launch vehicle structural temperature within acceptable limits during re-entry flights; that is internal temperature should not be higher than the limit required by the internal structure. TPS are usually composed of several layers of different materials. Heat transfer through a multilayer insulation during atmospheric re-entry involves combined modes of heat transfer: heat conduction and radiation through the solid, heat radiation to the outer space etc. In the framework of the TPS design activities, a procedure based on one-dimensional analytical solutions of transient non-linear analysis has been developed in order to estimate the temperature variation with time and space of a multi-layered body subjected to aerodynamic heating inside a radiating space. Furthermore a semi-analytical procedure, able to take also into account non-linear thermal properties, has been conceived. Since internal temperature values of TPS of re-entry vehicles cannot exceed certain values, these procedures allow to quickly evaluate these temperature values and the preliminary size layer thicknesses without resorting to numerical solutions. (C) 2011 Elsevier Masson SAS. All rights reserved.