预冷却引射系统性能一维分析

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-dimension design theory of ejector, cooling the secondary flow before it enters into the mixing chamber can promote the eject efficiency and increase the eject coefficient, but flow loss is brought with the addition of precooler, so the performance evaluation of ejector is necessary. Looking on the eject system with precooler, the effect of precooler on the performance of system was analyzed through the one dimension theory, and the effects of the intensifying effect of precooling and the weakening effect of resistance on eject efficiency were analyzed emphatically. The research results indicate that: the precooler brings intensifying effect of precooling and weakening effect of resistance to eject system, and the cross section area and heat transfer area of the precooler are the dominating factors; cross section area of the precooler has a critical value, when the cross section area is bigger than the critical value, the eject performance improves with the increase of heat transfer area, otherwise it worsens; the eject performance of the equivalent pressure mixing scheme is better than that of the equivalent area mixing scheme, the eject coefficient of the former is 60% higher than the latter; precooling improves the eject performance effectively, especially for the equivalent area mixing scheme, the performance is improved by 35.5%.