水泵水轮机转轮区域脉动特性分析

Analysis of fluctuation characteristics at runner area of pump turbine

为了揭示水泵水轮机转轮区域压力脉动特性,选取模型水泵水轮机为对象.基于Realizable k-ε湍流模型,对模型水泵水轮机不同运行工况进行三维非定常数值计算,研究水泵水轮机在不同水头下带部分负荷时转轮区域的脉动特性.研究结果表明:30%负荷情况下,随着水头的增加,转轮区压力脉动逐渐剧烈;在1个周期内,转轮上冠的压力脉动在时域特性上呈现周期性变化,而转轮出口轴线和与尾水管交界面处压力脉动在时域上相对紊乱;转轮上冠处压力脉动从进口边到出口边逐渐增大,其主频都为叶频,转轮出口边轴线上压力脉动都属于低频脉动,沿着负Z轴方向压力脉动幅值逐渐减小,转轮与尾水管交界面上压力脉动主频随着水头的增加逐渐减小,幅值的变化规律却相反.

In order to reveal the pressure fluctuation characteristics at the runner area of the pump turbine,pump turbine models were selected as the study object. Based on the Realizable k- ε turbulence model,three-dimensional unsteady numerical simulations were conducted and the pressure fluctuation characteristics of the runner were analyzed with part load under different conditions. The results show that when units with 30% load,the pressure fluctuation at the runner area becomes more severe with the head increasing. The pressure fluctuation characteristics at the upper canopy of the runner present periodic changes,and on the interface of runner outlet axis and the draft tube outlet the pressure fluctuation is in disorder in one cycle. The pressure fluctuation at the upper canopy of the runner increases from the inlet to the outlet,and its main frequency is the blade rotating passing frequency. The pressure fluctuation at the axis of the runner outlet is of low frequency and the amplitude decreases along the negative Z axis. The main frequency of pressure fluctuation on the interface of the runner and the draft tube decreases gradually with the head increasing,but the amplitude change is opposite.