Abstract
In the load rejection test of Kazunogawa pumped storage P. S. in Japan, an abnormal axial thrust occurred in a high-head reversible pump-turbine (412 MW and 714 m effective head). The rotating parts including a runner moved 4 mm upward in the axial direction. After taking several countermeasures, this machine is now operating without any problem, but the mechanism of transient axial thrust is not yet clear, though such a transient up-thrust has long been known. The present study is thus aimed to determine the reason why such abnormal axial thrust is caused at the transient operation and how to reduce abnormal thrust. Here adopted is a theoretical approach which has been proved to give satisfactory results in predicting pump axial thrust.
