非定常水斗表面自由水膜的流动机理

冲击式水轮机水斗内非定常自由水膜的流动非常复杂，至今还没有足够精确的数值方法来模拟这种流动．文中分析了非定常水膜流的流动机理，根据N-S方程推导出了水斗表面流体粒子在转动坐标系中的相对运动控制微分方程，依据控制微分方程编写出了数值解析软件并对水斗内的水膜流动进行了数值模拟，定量地得到了某模型水轮机水斗内部流动的速度场、能量场．对比一系列水膜流态分布，数值解析得到的结果与试验观测结果基本相吻合，最优工况下的水力效率与模型试验数据的误差为0．33％．

Mechanism of Unsteady Free Water Sheet Flow on Bucket Surface

The unsteady free water sheet flow in the rotating bucket of a Pelton turbine is a very complex flow that cannot be accurately simulated for lack of a numerical method.In order to solve this problem,the mechanism of unsteady water sheet flow is analyzed in this paper,and the differential equation describing the relative motion control of fluid particles on the bucket surface is deduced according to the Navier-Stokes equation in the rotating coordinate system.Then,a numerical analytical software is developed based on the proposed equation,which is finally applied to the numerical simulation of the water sheet flow in the rotating bucket,thus quantitatively obtaining the flow velocity and energy distributions of a model turbine.By comparing water sheet flows obtained by various experiments and simulations,it is concluded that the simulated results basically accord with the experimental ones,with an error in hydraulic efficiency of 0.33% in the optimum operation condition.