带有闭式布雷顿循环的预冷发动机特性研究

为获取带有闭式布雷顿循环的预冷发动机的飞行包线及性能，同时为提高发动机工程实现可行性，本文基于带有闭式布雷顿循环的预冷发动机基础循环及现有部件技术水平，构建了一种适度预冷发动机方案。对该方案下发动机沿着SABRE3飞行轨迹下的性能和部件匹配规律进行了分析。然后通过对发动机的高度、速度、调节特性进行研究，得到了该方案下发动机的飞行包线及整个包线内的性能。计算结果表明，本文所提出的适度预冷方案与SABRE3方案相比，核心机的比冲基本相当，但单位推力有所降低，工程可实现性提高；通过分别控制氦循环最低、最高温度为目标值，可保证发动机各部件在马赫数0~5的整个飞行过程中均处于稳定工作区间内，发动机比冲在1359 s~2099 s之间，地面点单位推力最大，达到1.9 kN/(kg/s)；特性研究发现发动机推力与比冲在高度0~15 km、马赫数1~3之间最高，而单位推力最高的区域主要集中在包线的左侧低马赫数区，随马赫数的增加逐渐降低；发动机对氦压气机前温度的调节十分敏感，而对氦涡轮前温度的调节敏感性较低。综合研究表明，本文所给出的适度预冷方案的预冷发动机具有较好的宽域工作能力。

Characteristics of Precooled Engine with Closed Brayton Cycle

In order to obtain the flight envelope and performance of the precooled engine with closed Brayton cycle and to improve the feasibility of the engine, a scheme of the precooled engine with moderate precooling was carried out based on the basic cycle and the existing component technology level. The performance and component matching law of the engine along the flight trajectory of SABRE3 were analyzed. Then the velocity characteristic, altitude characteristic and adjustment characteristic of the engine under this scheme were studied. And the performance throughout the flight envelope of the engine was obtained. The results show that the specific impulse of the engine with moderate precooling scheme proposed in this paper is basically the same with the core engine of SABRE3. However, the specific thrust is reduced and the engineering feasibility is improved. The engine can achieve stable control during the entire flight trajectory from Mach 0 to 5 by adjusting the minimum and maximum temperature of the closed helium cycle as the target value. The specific impulse range of the engine is between 1359 s and 2099 s, and the specific thrust at the ground point is the largest, reaching 1.9 kN/(kg/s). The characteristic study shows that the thrust and specific impulse of the engine are the highest between the altitude range from 0 to 15 kilometers and the Mach number range from 1 to 3. The part with the highest specific thrust is mainly concentrated in the low Mach number area on the left side of the envelope map. And the specific thrust gradually decreases as the Mach number increases. The engine is very sensitive to the adjustment of the inlet temperature of the helium compressor but insensitive to the adjustment of the inlet temperature of the helium turbine. Comprehensive research shows that the precooled engine with moderate precooling scheme presented in this paper has a wide range of altitude and speed.