Structural Stability and Modal Characteristics of Guide Vanes and Runner in a Pump-Turbine Based on Fluid–Structure Interaction

A fluid–structure interaction (FSI) model of the guide vane and runner of a pump-turbine was developed by applying unsteady hydraulic pressure loads obtained from CFD simulations to the structural surfaces. The deformation behavior, stress distribution, and modal response of the stay vane, movable guide vane, and runner were investigated under different operating conditions. The maximum deformation of the stay vane occurs at the middle section of the blade leading edge, whereas the maximum deformation of the movable guide vane is located near the trailing edge. The maximum deformation of the runner occurs at the junction between the blade leading edge and the band. Modal analysis shows that the fourth natural frequency of the movable guide vane approaches the eighth-order guide-vane passing frequency, while the sixth natural frequency of the runner approaches the fourth-order runner blade-passing frequency, suggesting a potential risk of vibration amplification.