阻尼孔水射流空化流动数值模拟

Numerical Simulation on Cavitation Flow of Water Jet with Damping Hole

对流场中空化现象进行数值模拟时,需要捕捉空泡生成发展到溃灭的过程以及该过程在流场中发生的位置。以阻尼孔淹没水射流为研究对象进行数值模拟时,考虑到水和水蒸气相变过程中两相具有压缩性,选择使用多相流混合模型并加入带有压缩性的正压方程进行描述。湍流模型选择kOmegaSST模型,对近壁面逆压梯度预测更准确,便于捕捉附着型空化现象。方程求解方法采用PIMPLE算法,在求解过程中每一个时间步内的变量根据情况采用不同的离散方法以达到稳定求解。数值模拟结果表明该方法可以捕捉到喉管处由于速度突变引起压力变化产生的附着空化,同时可以很好捕捉到喷嘴处与下游空泡的产生发展和溃灭过程。

it is necessary to capture the process from cavitation generation to collapse as well as to identify where the cavitation phenomena emerging in the flow field When numerically simulating cavitation phenomena in the flow field.Considering the compressibility of the two phases in the phase change process of water and vapor,the multiphase flow mixing model is selected and the barotropic equation with compressibility is added,when conducting the numerical simulation of the damping hole submerged water jet.The kOmegaSST model is selected as the turbulence model to predict the counterpressure more accurately near the wall,which is convenient to capture the attached cavitation phenomenon.The equation solving method adopts the PIMPLE algorithm.During the solving process,the variables in each time step need to adopt different discrete methods according to the situation to achieve stable solution.The numerical simulation results show that the method can capture the attached cavitation caused by the pressure change due to the sudden change of velocity at the throat,as well as the generation,development and collapse of cavitation at the nozzle and downstream.