水泵水轮机导叶卡门涡数值模拟研究

Numerical Simulation of Karman Vortex of Pump Turbine Wicket Gate

利用数值模拟方法,模拟水泵水轮机不同工况下,导叶出水边的卡门涡现象,揭示导叶下游侧流场涡量分布、导叶出水边附近卡门涡流动状态和流场脱流等。提取监测点速度变化曲线和导叶壁面垂直流向合力变化曲线,通过数据处理,获得水轮机工况和水泵工况,导叶出水边卡门涡频率分别是84.9Hz和53.3Hz。通过对比分析,证明利用经验公式计算得到的卡门涡频率存在较大误差,而数值模拟方法具有较高计算精度。研究结果对水泵水轮机导叶设计、避免发生卡门涡共振问题具有一定指导意义。

Karman vortex phenomenon near downstream side of wicket gate of pump turbineis simulated under different operating condition, by using numerical simulation method. Vorticity distribution, flow condition of Karman vortex, and flow separation behind wicket gate are revealed. Velocity curve of monitoring point andcurve of force on wicket gate perpendicular to flow directionare obtained, and Karman vortex frequency of wicket gate under turbine and pump operating condition are 84.9 Hz and 53.3 Hz respectively. It is proved that Karman vortex frequency obtained by using theoretical formula for flow around circular cylinder is not accurate, while numerical simulation method has higher accuracy.The research shows great significance inpump turbine wicket gate design and avoiding vibration induced by Karman vortex.