Abstract
A high amplitude vibration of powerhouse occurred in a pumped storage power plant. Through detailed measurements of pressure fluctuation in the volute, it was found that the vibration was caused by a high amplitude pressure fluctuation in the volute and that the amplitude becomes the maximum at the runner speed where the rotational speed of the rotor-stator interaction mode agrees with the sound velocity in water. This phenomenon called phase resonance was simulated by air tests using a fan for vacuum cleaner and the fundamental characteristics were clarified by developing a one-dimensional theoretical model. This is a good example showing that we still have many interesting problems in turbomachinery although it is considered to be a mature field.
