Investigation on thermal performance of high temperature multilayer insulations for hypersonic vehicles under aerodynamic heating condition

Hypersonic vehicles have to withstand extremely high aerodynamic heating and pressure loads during the ascent and reentry stages. Multilayer thermal insulations have been widely designed in thermal protection systems to keep the temperature of underlying structure within an acceptable limit. In this study, a theoretical model is built combining radiation and conduction heat transfer in high temperature multilayer insulations under aerodynamic heating conditions. After a reliable validation with previous references, the effects of the layout, the number and the location of the foils, the density of insulation materials and the emissivity of the surface of foils on the insulation performance of multilayer thermal insulations are investigated, respectively. It is found that there exists an optimal number of insulation layers for best thermal performance and the layout of radiation foils has no evident effect. In addition, the insulation performance is much better when the foils are near the cold boundary, and when the density of insulation material and the emissivity of the surface of foils are higher, the temperature of bottom surface is lower.