应用三维空间导叶的混流式水轮机流动

为减小混流式水轮机转轮内的叶道涡,设计了两种三维空间导叶,推导了流量调节方程,采用了全三维全流道的湍流计算方法,完成了从蜗壳进口到尾水管出口,包含所有流道在内的数值计算;并进行了模型对比试验。结果显示:应用三维空间导叶对水轮机能量性能没有太大的影响,但是增大了活动导叶上部的水流出口角,从而减小了转轮叶片进口处的冲击,尤其是在高水头、小开度情况下,上冠处的冲击和脱流比二维常规导叶有明显改善,降低了叶道涡发生的可能性,提高了水轮机的运行稳定性。

Flow in a Francis turbine with a three dimensional gate vane

New three dimensional gate vanes were designed to reduce channel vortices in Francis turbine runners.The discharge equation for the gate vanes was derived based on a three-dimensional theoretic analysis.The flow in the whole turbine flow passage from the spiral case inlet to the draft tube outlet was then simulated numerically.The numerical and experimental results showed that the new gate vanes have little influence on the turbine efficiency,but increase the flow angle on the upper surface of the gate vanes which result in decreasing the impact on the runner inlet.Especially for high head and low discharge conditions,the vanes reduce the separation on the crown better than the two-dimensional gate vanes,reduce the channel vortices,and improve the Francis turbine's stability.