超音速喷射器内部流场及变工况CFD分析

CFD Analysis on Flow Field and Performance of Supersonic Air Ejector

针对超音速空气喷射器的性能进行了数值研究,得到了喷射器内部的压力场和流动特性,并计算了喷射器的变工况特性。分析表明,当喷射器工作背压小于临界背压时,混合室中的压力基本为定值,喷射系数不变,在混合室中或出口处出现激波链;当工作背压达到临界背压时,激波链收缩到混合室入口,混合室中的定压混合过程消失;当工作背压大于临界背压,在混合室的入口处产生强激波链,出现阻塞,喷射器系数减小。此外,随着工作流体压力的升高,对应的临界背压增大,当工作压力比较低时,激波链从混合室出口向混合室入口收缩的速度更快。

The numerical research on the supersonic air ejector was carried out. The static pressure distributions and flow characteristics in the ejector were obtained, and the performances of ejector at various operating parameters were analyzed. The results indicated that, as the operating back pressure was lower than the critical back pressure, the static pressure in mixing chamber and entrainment ratio were almost constant, and a series of shock waves occurred at the exit of mixing chamber or in mixing chamber. As the operating back pressure was equal to the critical back pressure, the shock waves moved to the entrance of mixing chamber, and the mixing process of constant static pressure in mixirlg chamber was disappeared. As the operating back pressure was higher than the critical back pressure, intense shock waves occurred at the entrance of mixing chamber, the flow was choked and the entrainment ratio decreased. Moreover, the critical back pressure increased with the primary pressure, and shock waves moved faster to the entrance of mixing chamber for lower primary pressure.