Performance analysis of hypersonic vehicle with integrated thermal protection and propulsion based on liquid ammonia-aviation kerosene

Hypersonic vehicles flying at high Mach numbers face severe aerodynamic heating on their outer surfaces. Active cooling is an effective thermal protection method. Convection cooling shows the best application prospects but lacks comprehensive research on its impact on vehicle performance. We propose a scramjet engine using ammonia-aviation kerosene dual fuels. Liquid ammonia's high heat sink efficiently cools the aircraft wall, and the recovered heat improves engine propulsion. In order to comprehensively evaluate the cooling effect and propulsion performance of the dual-fuel engine, a thermodynamic model of the dual-fuel scramjet engine was established, and the system performance when aviation kerosene, liquid ammonia, liquid hydrogen and water were used as coolants was also compared and analyzed. Results show the ammonia-kerosene dual-fuel engine has the highest specific thrust and total efficiency, with thermal protection second only to low-temperature liquid hydrogen. At the optimal blending ratio, the specific thrust is increased by 2–25 %; the cooling effect is improved by 15–35 %; and the required generalized heat exchange area is reduced by 40–60 %. In summary, the calculation shows that the dual-fuel engine with convection cooling has significant quality advantages and system-level advantages. The research results provide insights for the subsequent research direction of active convection cooling.