预冷组合循环发动机吸气式模态建模与性能分析

为了对预冷组合循环发动机开展性能分析，以协同吸气式火箭发动机（SABRE 4）为研究对象，采用部件法建立了发动机稳态模型，计算获得了SABRE 4发动机在吸气式模态下沿飞行弹道的性能参数变化规律。然后对发动机的高度和速度特性进行研究，得到了发动机的飞行包线。计算结果表明，在吸气式飞行弹道内，核心机推力和比冲的变化分别为488~680kN和34786~46954m/s。SABRE 4发动机具备推力大和比冲高的性能优势。在预冷器工作过程中，随着飞行马赫数增大，预冷器换热量不断增大，进入预燃室的氢流量减小，预燃室总温降低，HX3的吸热量减小。与其他压气机和涡轮相比，空气压气机和氦涡轮的工作参数变化较大。SABRE 4发动机通过对来流空气进行预冷，可实现在大空域和宽速域内工作。由于空气压气机的喘振和堵塞边界限制，发动机的高度和速度特性分别存在飞行高度和飞行马赫数的限制。

Modeling and Performance Analysis of Precooled Combined Cycle Engine in Air-Breathing Mode

In order to carry out performance analysis for precooled combined cycle engine, a component-level model was developed for Synergetic Air-Breathing Rocket Engine (SABRE4). The variation of performance of SABRE4 engine in the air-breathing mode along the flight trajectory was obtained. Then the altitude and velocity characteristic of the engine were studied, and the flight envelope of the engine was obtained. The results indicate that the range of thrust and specific of core engine is 488~680kN and 34786~46954m/s respectively during the air-breathing trajectory. SABRE4 engine has the performance advantages of large thrust and high specific impulse. During the operation of precooler, as the flight Mach number increases, its heat transfer rate increases, the mass flow rate of hydrogen into pre-burner decreases, the total temperature of pre-burner reduces, and the heat absorption of HX3 decreases. The operation parameters of air compressor and helium turbine vary significantly compared with other compressors and turbines. SABRE4 engine is capable of operating in the large airspace and wide speed range by precooling the incoming airflow. Due to the constraint of the surge and blockage boundary of air compressor, the altitude and velocity characteristics of the engine have the flight altitude and Mach number limit.