船舶螺旋桨黏性空化流场数值方法

Nnumerical method for viscous cavitating flow around ship propeller

以螺旋桨E779a为对象研究适合螺旋桨黏性空化流场的数值方法.基于黏性多相流理论,在均匀入流条件下数值求解纳维-斯托克斯(N-S)方程和空泡动力学方程组来预报螺旋推力系数KT、轴向速度UX和蒸汽体积分数av.数值结果表明,增加螺旋桨盘面至压力出口的计算空间距离后KT和UX的准确性提高了约3%.螺旋桨外围圆柱形规则区域用结构网格划分可以明显改善片空化的预报.对于相同网格策略,网格尺寸在一定范围内减小对片空化位置、KT和UX的预报结果影响不大,但片空化程度预报的准确性提高23%.网格收敛指数表明网格无关性较好,标准k-ω模型使计算容易收敛,大涡模型可提高UX和湍流动能的预报精度.

The numerical method for viscous cavitating flow field was studied with propeller E779a.Based on viscous multiphase flow theory,Navier-Stokes（N-S） and Bubble Dynamics equations were solved to predict propeller thrust coefficient KT,axial velocity UX and vapor volume fraction av in an uniform inflow.The numerical results indicate that the accuracy of the predictions of KT and UX is improved by 3% with increasing the distance from propeller disk to pressure outlet in computational domain.A sheet cavitation is better predicted with the structured grid in outer domain with regular shape of column.For the same grid strategy,the size of grid cells decreased within certain limits has little influence on the prediction of position of the sheet cavitation,KT and UX,but enhances the accuracy of the prediction of the sheet cavitation degree by 23%.The grid convergence index demonstrates good grid dependence.The standard k-ω turbulence model makes calculation more convergent.The LES（large eddg simulation） improves the accuracy of the prediction of UX and turbulence kinetic energy.