Additional Water Mass in Pump Impeller Vibration

It is well known that the water contained in the pump impeller has the additional mass effect when the pump rotor vibrates in water, but no theoretical discussion has been presented about the analytical method used to evaluate it. In this paper, two additional water mass effects for the lateral vibration and the torsional vibration are discussed by the experiment and the approximate analytical method, and it is ascertained that almost all the water in the impeller is effective for the lateral mode. On the other hand almost no water is effective for the torsional mode.