Investigation on Nonlinear Fluid–Thermal–Structural Interaction of a Coated Scramjet Combustor

Scramjet-based airbreathing hypersonic vehicles require weight-optimized structures that can reliably withstand severe aerothermodynamic loads induced by shock waves, viscous effects, and supersonic combustion. The propulsion system’s performance during sustained hypersonic flight is strongly dependent on the deformation and thermal states of such structures. This paper numerically investigates the nonlinear fluid–thermal–structural interaction (FTSI) phenomenon in an axisymmetric cavity-based scramjet combustor using a rigorously validated coupling framework. The combustion flowfields are prominently altered by the increased wall temperature, manifested as upstream moving of shock waves, redistribution of the key intermediate combustion product, and improved combustion efficiency. Additionally, the FTSI tends to drive the combustion regime transition from subsonic to transonic. Under the simulated 40 s flight condition, creep effects are negligible, whereas extensive plastic yielding occurs. Without a thermal barrier coating (TBC), material failure is observed near the cavity trailing edge where peak temperature occurs. TBCs can effectively protect the base material by reducing substrate temperature by [Formula: see text] while simultaneously increasing hot-gas-exposed surface temperature to [Formula: see text] for enhanced combustion efficiency. Results from this study demonstrate that even for such a short duration, a reliable design for scramjet engines must account for FTSI-induced impacts on both combustion performance and structural integrity.