Effects of combustion–thermal–structural coupling on supersonic combustion and structural response in axisymmetric scramjet

This study employs a loosely coupled method to analyze the flow, combustion, and structural response mechanisms of a three-dimensional axisymmetric scramjet under combustion–thermal–structural coupling over a 30 s duration. On a macroscopic timescale, results from the Reynolds-averaged Navier–Stokes (RANS) method reveal three distinct operating stages induced by coupling effects: combustion enhancement, mode transition, and combustion stabilization. The characteristics of multiple fields at each stage have been explored. On a microscopic timescale, the unsteady RANS method is utilized to investigate the dynamic mode transition process. Cavity shear layer combustion transitions to jet wake combustion within 7.54 ms, driven by a positive feedback loop where heat release from combustion and chemical reactions at the wavefront mutually reinforce, increasing back pressure and accelerating the transition. Structurally, coupling effects generate multiple high-temperature regions, leading to a 1.4% axial elongation rate by 30 s. Rapid heating initially induces high-stress regions, but prolonged heating promotes temperature homogenization, reducing stress levels. The study highlights the significant and nonnegligible impacts of coupling effects on flow, combustion, and structural dynamics.