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根据引射器的一维设计理论可知,二次流在进入混合室之前进行预冷降温可以提高引射效率,增大引射系数,但引入预冷器会同时引起流动损失,故需要对引射系统进行性能评估。针对设有预冷器的引射系统,应用一维理论分析预冷对系统性能的影响,重点分析预冷增强效果与流阻减弱效果对引射效率的作用。研究发现:预冷器对引射系统同时带来冷却增强作用和流阻减弱作用,横截面积和换热面积是主要影响因素。预冷器存在临界横截面积,横截面积大于临界值时,换热面积越大,引射性能越高;反之,换热面积越大,引射性能越低。等压混合引射方案比等截面混合引射方案性能高,前者引射系数比后者大60%;预冷却能够有效提高引射性能,尤其是等截面混合引射方案,性能提高可达35.5%。
According to the one-dimensional design theory of the ejector, it can be seen that pre-cooling of the secondary flow before entering the mixing chamber can increase the efficiency of injection and increase the coefficient of injection, but the introduction of the pre-cooler will cause the flow loss at the same time. Shooting system for performance evaluation. For the injection system with precooler, one-dimensional theory is applied to analyze the influence of precooling on the system performance. The emphasis is put on the effect of pre-cooling enhancement and flow resistance attenuation on the injection efficiency. The results show that the precooler brings about both cooling enhancement and flow resistance reduction of the injection system, and the cross-sectional area and heat transfer area are the main influencing factors. Pre-cooling device has a critical cross-sectional area, the cross-sectional area is greater than the critical value, the larger the heat transfer area, the higher the injection performance; the contrary, the larger the heat transfer area, the lower the injection performance. Equal pressure mixed injection scheme than the equivalent cross-section hybrid injection scheme performance, the former index greater than the latter 60%; Pre-cooling can effectively improve the injection performance, especially the cross-section hybrid injection scheme, the performance improvement of up to 35.5 %.