发动机/扩压器不同安装方案对高模试车启动过程的影响

某上面级发动机高模试车时,喷管扩张段外壁面某处出现了氧化烧蚀,针对此现象进行了高模试车时的启动过程数值仿真研究,结果表明:试验状态和两种改进方案下,喷管内和扩压器内的流场均在0.1 s已经达到稳定状态,其马赫数和静压等流场参数不再随时间的推进而变化;发动机在启动过程中,喷管出口的高温燃气均会倒流进入真空舱;试验方案燃气倒流量最多,改进方案一燃气倒流量最少,改进方案二燃气倒流量介于试验方案和改进方案一之间;综合比较,改进方案一最佳,是防止发动机高模试车启动过程中燃气倒流烧蚀喷管外壁的一种措施。

Effect of different engine/diffuser installation schemes on start-up process in high attitude test

During the high-attitude simulation test of an upper-stage engine,oxidation and ablation occurred somewhere on the outer wall of nozzle expansion section.Aiming at this problem,a numerical simulation on the start-up process of the high-altitude test was carried out.The results show that the flow field in the nozzle and the diffuser has reached a stable state within 0.1 s under the test state and two improved schemes,and the flow field parameters,such as Mach number and static pressure,do not change with time.During the start-up process of the engine,the high-temperature gas at the nozzle outlet will flow back into the vacuum chamber.The experimental scheme has the most gas backflow while the improved scheme I has the least gas backflow,and the improved scheme II has a gas backflow between the experimental scheme and the improved scheme I.By the comprehensive comparison,it is considered that the improved scheme I is the best,which is an effective measure to prevent gas backflow from ablating the outer wall of nozzle during the engine start-up process in high-attitude test.