Heat transfer simulation considering coupling between the regenerative cooling and supersonic combustion under different solid thermal conductivities

Ceramic matrix composites (CMCs) have strong application potential for regenerative cooling structures in high-Mach-number scramjets due to their excellent high-temperature resistance. Compared to high-temperature alloys, CMCs exhibit a much wider range of thermal conductivity, which significantly affects the aerodynamic thermal load of regenerative cooling structures. This study develops an efficient three-dimensional numerical model to simulate the coupled heat transfer between the aviation kerosene cooling channel and the supersonic combustor. This approach addresses the limitations of traditional single-channel models, enabling accurate reflection of the matching mechanism between solid thermal conduction and aero-thermal load. Unlike conventional heat transfer enhancement strategies, our findings demonstrate that maximizing the high-temperature resistance of CMCs requires reducing their thermal conductivity to inhibit the coupled heat transfer within the cooling structure. Specifically, reducing solid thermal conductivity from 120 W/(m·K) to 3 W/(m·K) cuts combustor heat dissipation by 53 %, raising wall temperature from 1223 K to 2057 K. However, excessively low thermal conductivity leads to extremely high local temperatures of kerosene and a risk of thermal stress damage. Through a comprehensive analysis of heat transfer and strength, the average thermal conductivity of CMCs should neither be too high nor too low, with a recommended value of 50 W/(m·K).