Effect of thermal protection system size on aerothermoelastic stability of the hypersonic panel

The design optimization of Thermal Protection System (TPS) for airbreathing hypersonic vehicles is typically carried to resolve aerodynamic heating concerns. The target is achieved through material selection and structural configuration so that the resultant TPS is light weight and provides sufficient insulation. However, in this investigation, aerothermoelastic stability is also incorporated into TPS size design. A simplified arrangement consisting of an underlying panel and TPS with a thermal radiation coating and an insulation layer is investigated. The two-way fluid-thermal-structure coupling scheme includes mutual interaction between panel deformation and aerodynamic heat flux. The coupling aerothermoelastic model is first verified by comparing with the seminar work by Culler. Subsequently, the fluid parameter studies in terms of transitional location and radiation emissivity are then conducted on the verified model. A parametric study is conducted such that seven TPS size cases with various layers thickness are selected and compared in terms of structural weight and onset of flutter. Finally, the aerothermoelastic stability regions manifested by Flat, Buckled, Chaos and Quasi-periodic features pertaining to Mach number, flight height and TPS size are mapped out. The results indicate that TPS size can alter the panel aerothermoelastic stability boundaries in an obvious way. A new finding is that the TPS size in the pioneering work by Culler is not the best design either for a higher flutter boundary or for a lighter weight. In contrast, Case2 and Case7 in this study are better choice due to the delay in onset of flutter with lighter weight. This study necessitates aerothermoelastic analysis in TPS optimization design for the airbreathing hypersonic vehicles.