Influence of Guide Vane Shapes on Hydraulic Characteristics for a Shaft-Extension Tubular Pump Turbine at Turbine Mode

Guide vanes are important components for a shaft-extension tubular pump turbine. To study the influence of guide vanes on the performance of a shaft-extension tubular pump turbine, three guide vanes with different section profiles are prepared. The steady flows through the whole passage of the shaft-extension tubular pump turbine with different guide vanes are simulated based on RNG k-ε turbulence model. The numerical results show that the section profile of a guide vane influences the hydraulic performance of the pump turbine. It is noted that the pump turbine with the guide vane profile having a large curvature has a broader operation range with high efficiency, and the minimal hydraulic loss among three guide vanes. Further investigation depicts that the static pressure and velocity distribution in the guide vane are relatively uniform, and there are hardly flow incidence at the leading edge and little low pressure zone near the suction side for the suitable guide vane profile.