一种新型喷射器的内部流场分析

CFD Modeling of an Innovative Ejector

运用CFD数值模拟方法对比研究了普通喷射器和新型喷射器内流体流动情况。结果表明,新型喷射器的设计实现了壁面型线的合理变化,有效削弱了喷嘴出口激波系的强度,避免了引射流体在喷嘴出口发生边界层分离、回流及由此引起的不可逆损失;同时也增加了工作流体和引射流体混合过程中的接触面积,有利于对引射流体的抽吸和两股流体间进行更为充分的动量和能量交换,使得混合流体在喉管出口得到更为均衡的速度,并且避免了扩压室入口处激波的产生和由此导致的混合流体边界层分离,进一步提高了喷射器的性能。

The flowing field of a conventional ejector and an innovative ejector were investigated by using CFD simulation. Resuits indicate the wall structure of the innovative ejector is arranged in such a way that it can effectively impair the strength of the shock wave train occurring at the exit of the nozzle, and avoid the boundary lay separation and recirculation of the entrained fluid which greatly reduces the irreversibility loss. Meanwhile, it also extends the contact area between the working fluid and entrained fluid which is good for a more adequate energy and momentum exchange between them, so that a more uniform velocity can be obtained at the exit of the constant area tube. What＇s more, it avoids the shock wave occurrence at the inlet of the diffuser and the resulting boundary layer separation of the mixture, and further improves the performance of the ejector.