A novel numerical model for evaluating the high-frequency vibration intensity of the headrace tunnel in pumped storage power station

High-frequency pressure pulsation induced by the rotor-stator interaction is a frequently observed phenomenon in pumped storage power stations. The propagation of the pulsation can induce severe problems associated with the vibration and noise in the headrace tunnel. Considering this engineering problem, we aimed to develop a numerical model for predicting the vibration identity of the headrace tunnel and to provide boundary condition for investigating the environmental vibrations. In the proposed numerical model, the interactions in the fluidpipe-surrounding medium system were considered. And the effect of the surrounding medium was decoupled based on the propagation characteristics of P- and S-waves. The established numerical model avoids the need to solve for the dynamics of the entire surrounding medium. The results derived from the proposed time-domain model were compared with those obtained from the frequency-domain model and 3D FSI simulation, which validated the correctness of the proposed numerical model. Simulation results for an actual pumped storage power station revealed that, considering the influence of surrounding rock, the vibration amplitude of the pipe wall was on the order of 10-7m. This amplitude was reduced by over tenfold, indicating that the surrounding rock significantly dampened the vibration intensity of the headrace tunnel.