高水头水泵水轮机转轮的抗振防裂纹设计

Anti-vibration and Crack Control Design of High-head Pump-turbine Runner

流体激发转轮振动是目前高水头水泵水轮机稳定运行的关键问题之一。转轮的振动问题主要是由于活动导叶和转轮叶片之间形成的无叶区内不稳定流体相互作用所引发的水力激振在转轮上的力学响应。通过对叶栅干扰的产生机理分析,揭示了这种水力激振力的频率和振型决定于不同活动导叶数和转轮叶片数形成的叶栅组合方式,当转轮在水下的固有频率以及与之相对应的同相振型或反相振型同水力激振力发生耦合时,将会诱发转轮共振,并造成疲劳破坏。结果表明,选择最佳的叶栅组合可以最大限度地降低转轮发生共振的可能性,采用有限元法开展转轮结构的水下振动特性分析和控制局部高应力水平,以及保证良好的制造质量,可以有效提高转轮的抗振防裂纹能力。

Runner vibration excited by fluid is one of the key issues in the stable operation of high-head pump-turbine. Runner vibration is the mechanical response of hydraulic excitation induced by interaction of unstable fluid in vaneless gap between wicket gates and runner blades. It is concluded that the frequency of hydraulic exciting force and vibration mode depend on the relationship of numbers of wicket gates and runner blades. When the natural frequency of runner in water and the corresponding cophase and antiphase vibration mode are coupled with hydraulic exciting force, the runner resonance will be occurred which could cause fatigue failure. Results show that choosing the optimal relationship of numbers of wicket gates and runner blades could awfully reduce the possibility of runner resonance. By using finite element method, vibration characteristics of runner in water are analyzed and the local high stress level is managed. Then, the high manufacturing quality is ensured and anti-vibration and crack control ability of runner is improved.