Numerical analysis of misaligned guide vanes effect pressure oscillations in a prototype pump turbine

The unsteady Reynolds-averaged Navier-Stokes equations with the k-ω based SST turbulence model were solved to model the unsteady flow within the entire flow passage of a large Francis Pump turbine with misaligned guide vanes (MGV) device under the rotated speed. Four MGV with three different MGV openings are chosen to analyse the influence of pressure pulse in turbine modes. This study investigates the characteristics of the dominant unsteady flow frequencies in different parts of the pump turbine for various MGV openings. The hydraulic performance and pressure fluctuations were predicted numerically. The computed result shows that the MGV can decrease the relative amplitude in the state part of flow passage, but not for the rotator runner blades.