混流式喷水推进器空化性能数值分析

基于RANS方程，结合切应力输运湍流模型计算某混流式喷水推进器无空化状态时的流体动力性能。与厂商提供的数据对比表明，建立的数值模型和计算方法是可信的。在此基础上，嵌入基于Rayleigh-Plesset方程的混合物均相流空化模型，对空化条件时该喷水推进器流体动力性能进行数值计算与分析。计算得到的功率、推力等宏观量与厂商提供的数据吻合较好。计算得到空化发生时的临界进口速比值。计算结果表明，喷水推进器叶轮发生空化时，泵的流量、扬程明显降低，进而引起推力下降；在等功率条件下，随着进口速比的降低，喷水推进器叶轮空化程度越来越严重；进水流道空化的发生较喷泵叶轮空化滞后，喷口部分仅产生空间空化，较叶轮空化提前，而固壁上不产生空化；数值计算结果还证明空化限制线即为等汽蚀比转速线，且空化限制线1、2、3对应的汽蚀比转速分别约为1 280、1 390和1 580。

Numerical Simulation of a Mixed-flow Waterjet Cavitating Performance

With SST turbulent model, non-cavitating hydrodynamic performance of a mixed-flow waterjet is obtained by calculating RANS equations. The comparison between calculation results and data from manufacturer shows that the numerical model and method is creditable. The cavitating hydrodynamic performance of it is calculated and analyzed with mixture homogeneous flow cavitation model based on Rayleigh-Plesset equations. Numerical results, such as power and thrust, have good accordance with manufacturer's data. The critical IVR when cavitation occurs is obtained. The calculation results show that mass flow rate and total head of the pump are reduced when cavitation occurs on the blades, and thrust declined. The cavitation on blades gets much severer as IVR falls under constant power condition. Inlet duct cavitation lags behind the blade cavitation, and the nozzle cavitation in form of spatial cavitation occurs ahead of the blade cavitation, but there is no cavitation on nozzle wall. The results also prove that the limiting cavitation line is a constant suction specific speed line, and their values are approximate to 1 280,1 390 and 1 580.