Mode transition control law analysis of ammonia MIPCC aeroengine considering inlet–compressor safety matching

Inlet–Compressor (I–C) safety matching is a key technology for successfully implementing the mode transition of a turbine-based combined-cycle (TBCC) engine. To investigate the performance variation in Ammonia mass injection pre-compressor cooling (MIPCC) aeroengines (AMAs) during the mode transition, a model considering inlet–compressor engine safety matching was developed in this study. We provide a computation for the inlet unstart margin ξ which considers the positive shock wave assumption, I–C flow conservation equation, and combined inlet characteristics to assess the degree of I–C matching. Furthermore, the AMA characteristics indicate that the total pressure recovery coefficient of the hypersonic combined inlet has significantly affects the engine performance. The restraint ξ also ensures engine safety. A control law guided by ξ and the combustor outlet temperature (ξ–COT) was proposed to enhance the specific impulse and specific thrust of the AMA. Compared with the speed and COT control laws, the specific impulse and specific thrust were maximally improved by 2.93 % and 5.47 %, respectively, when ξ = 0.2. Both were further improved by 5.91 % and 10.49 %, respectively, when ξ = 0.1. Finally, the high-thrust performance results of the AMA, with the optimized control law ξ–COT during the mode transition process, were obtained.