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

This article focuses on the investigation of combustion–thermal–structural coupling effects in a three-dimensional axisymmetric scramjet operating at Mach 2.5, using a loosely coupled numerical method. The study identifies three combustion stages—combustion enhancement (CE), mode transition (MT), and combustion stabilization (CS)—characterized by a transition from cavity shear-layer stable combustion (CSL mode) to cavity-assisted jet-wake stable combustion (CAJW mode). On a microscopic timescale, the MT stage involves a rapid combustion mode transition within 7.54 milliseconds, driven by increased back pressure and a positive feedback loop between chemical reactions and heat release. Structurally, coupling effects produce multiple high-temperature regions, localized high stress, and an axial elongation rate of 1.4% after 30 seconds, with stress concentrations linked more to temperature non-uniformity than absolute temperature. The findings highlight the significant interplay among flow dynamics, combustion behavior, and structural responses in scramjet operation under coupled physical effects.