Abstract: The advanced propulsion system serves as the fundamental support for the horizontal takeoff and landing reusable hypersonic vehicle. Among the various power schemes, the hypersonic precooled engine has garnered significant attention in recent years due to its high potential. Therefore, it is crucial to conduct an in-depth investigation into the thermodynamic cycle of precooled engine and acquire a deep understanding of its working characteristics. This paper provides a comprehensive review of the domestic and overseas progress of hypersonic precooled engine thermodynamic cycle. The review encompasses various aspects, such as the modeling and analysis methods em-ployed for engine thermodynamic cycle, the performance analysis methods and the typical thermodynamic cycle schemes of precooled engines. The direct precooled cycle and the indirect precooled cycle with intermediate medi-um are introduced respectively due to these marked differences. The research has shown that fuel type is the fun-damental factor to determine the performance of direct precooled engine cycle, as well as improving the heat sink of fuel is an important way to improve the performance of engine. As for the indirect precooled engine with closed cy-cle, there are some contradictions between the specific impulse, thrust of engine and the complexity of closed cycle. On the whole, it is necessary to further study on the key components of hypersonic precooled engine, refine more accurate component performance models, improve component size, weight and other estimation models, in order to achieve accurate evaluation of engine specific impulse, thrust, thrust-to-weight ratio and other overall performance parameters, and then support the highly feasible thermodynamic scheme design of hypersonic precooled engine.

Key words: hypersonic, precooled engine, combined cycle engine, thermodynamic layout, control law