蒸汽发生器掺混工质对引射性能的影响分析

Influence of steam generator's mixture on its ejection performance

在火箭发动机高空模拟试验领域,常采用蒸汽发生器供应大流量的引射工质。蒸汽发生器利用燃料和氧化剂化学反应,并和掺混工质混合产生引射工质。为了分析掺混工质对蒸汽发生器供应引射工质的性能的影响,开展了理论计算研究。首先,分析了冷却水掺混量变化对引射器零二次流引射性能的影响,结果表明在最小启动压力点,随着冷却水量增加,最小启动压力增大,真空度提高,一次流流量增加,消耗的酒精先减小后增大;其次,分析了采用不同流量液氮作为掺混工质的引射效果,结果表明在最小启动压力点,随着液氮量增加,最小启动压力增大,真空度提高,一次流流量增加,消耗的酒精减少;最后,比较了2种掺混方法,发现采用液氮作为掺混工质,极限真空度更高,引射能力为采用水掺混的3倍。对于带有二次流的超超引射,二次流一致时,2种方式的压缩比相当,但液氮掺混工作范围更宽。

In the field of altitude test of rocket engines, steam generator is usually used to supply high-flow ejecting gas. In the steam generator, fuel reacts with oxidant and blends with mixture to produce ejecting gas. This paper studied the influence of mixture on performance of ejecting gas based on theoretical calculation. Firstly, the performance of a supersonic ejector without a second flow with ejecting gas mixed with different volumes of water was studied. The results show that at the minimum start pressure point, when the cooling water volume increases, a bigger minimum start pressure is needed and the vacuum level increases while more ejecting gas is required with alcohol consumption first decreases and then increases. Secondly, the performance of a supersonic ejector with ejecting gas mixed with different volumes of liquid nitrogen was studied. The results show that atthe minimum start pressure point, when the liquid nitrogen volume increases, a bigger start pressure isneeded and the vacuum level increases while more ejecting gas is required with less consumption of alcohol. Finally, the comparison of the two blending methods shows that using liquid nitrogen as mixture brings a higher vacuum level and an ejecting performance three times better than that of using water. As for supersonic-supersonic ejector with a second flow, the compression ratios are the same under the same second flow but the liquid nitrogen has a larger work scope.