Abstract: 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.

Key words: Cascade interference, Hydraulic excitation, Pump-turbine, Resonance, Runner