Abstract
In order to clarify the mechanism of the vibration phenomenon which occurs when a pump-turbine stops suddenly, the experiment of the pump-turbine were performed in this research. The pressure are measured at inlet and outlet with changing flow rate, rotating speed and guide vane opening. "S-shape curve" was observed in the turbine characteristic curve. The past research clarifies that appearing "S-shape curve" means vibration phenomenon occurs. The experimental result shows that as the guide vane opening is smaller, ψ is larger. In the value of φ/φ_d from 0.3 to 0.6, the fluid vibration occurs with the 20 degree GV and the 34 degree GV. On the other hand, with the 8 degree GV, the fluid vibration doesn't occur.
