考虑气蚀效应的气液两相冲压发动机数值模拟

针对一种新型水下气液两相冲压发动机，综合考虑了湍流效应、气液两相之间的拖曳作用及传热与传质，利用计算流体力学方法研究了气液两相冲压发动机内流场的流动特性随发动机工作条件的变化规律，重点研究了气蚀效应对发动机工作性能的影响.主要结论为:当航行速度大于32 m/s，气液两相冲压发动机入口附近会产生气蚀并造成严重的总压损失，导致扩张段下游产生流动分离，此时发动机无法产生正推力；通过增大气体质量流率，气液两相冲压发动机内流场的压力将会随之升高，气蚀效应被抑制；提高注入发动机气体的温度，发动机的推力及比冲均增大，但是发动机效率急剧降低. 

Numerical Investigation of Two-phase Underwater Ramjet Considering Cavitation Effect

The performance of a typical two-phase underwater ramjet and its inner flowfield were investigated by the application of computational fluid dynamics method and the effect of cavitation was taken into account. The research shows that when the engine is cruising at a relatively high speed, cavitation will occur at the inlet of the engine and cause serious total pressure loss, which leads to flow separation at the middle of the diffuser and serious drop in engine performance. With the increasing of mass flow rate of the injected air, the mixing chamber pressure increases noticeably and the cavitation disappears. Moreover, the thrust and specific impulse can be promoted by increasing the temperature, but the overall efficiency will decrease dramatically.