Study on the dynamic response behaviour of the head cover-bolts-stay ring of a variable-speed pump-turbine

Abstract The vibration characteristics of the hydro-turbine’s head cover is a significant factor that affects the safety of the unit. This paper established the Finite Element Method (FEM) model for the head cover-bolts-stay ring system of a variable-speed pump-turbine, and the dynamic response behaviour of the system under pretension and hydraulic excitation conditions is analyzed. The results indicate that the maximum value of stress locates at the bolt root, which is 715.6MPa under pretension load and 678.7MPa under hydraulic excitation. The results presented in this paper offer valuable guidance for the safety and stability of the variable-speed pump-turbine.