混流式水轮机叶道涡引起的振动问题研究

Research on the Vibration of Francis Turbine Caused by Channel Vortices

西南某电站的混流式水轮机在高于额定水头、满负荷及超负荷下,出现异常振动。分析发现振动工况特征点位于转轮运转特性曲线上叶道涡范围的部分区域内,并预测在叶道涡区域的其他部分也存在引起机组振动的特征工况点。后赴电站现场作了起始于满负荷的降负荷试验,试验数据证实了先前的预测。CFD数值分析也表明,在振动工况下,转轮叶片间存在明显涡流,则认为该电站水轮机在高水头高负荷下的振动是由叶道涡引起的。

Severe abnormal vibration appears in Francis turbines in a hydropower station of Southwest China at the higher head than the rated head and full load or overload .To investigate the reasons ,the analysis considers that characteristic points of vibration con-dition are inside a part of the channel vortex area on the runner＇s performance curve .And after dropping load test starting at full load in the power plant site ,the test data confirm the prediction that the other parts of channel vortex area also have analogous character-istic points of vibration conditions .The CFD analysis also demonstrates that the obvious unstable vortices exist between runner blades under the vibration condition .So the vibration of these turbines is caused by channel vortices when they operate at the zone with the higher head than the rated head and the full load or overload .