Author(s): Yue Lv; Lingjiu Zhou

Linked Author(s):

Keywords: Pressure-balance pipe; Pump-turbine; Volumetric efficiency; Clearance leakage

Abstract: Hydraulic machinery experiences volume loss due to flow leakage from the clearance between rotating parts and the shell. For pump turbines, fluid leakage from high-pressure to low-pressure areas through the clearance between the upper crown and lower band sealing parts causes volume loss and reduces hydraulic efficiency. The pressure-balance pipe is crucial for balancing axial hydraulic thrust, and its starting end typically lies on the inner side of the upper crown clearance. In this study, we analyze a pump turbine with three flow rates (0.9Q, 0.75Q, and 0.5Q) to illustrate the impact of clearance flow on volumetric efficiency. We consider the effect of varying pressure-balance pipe diameters on volumetric efficiency and analyze the influence of diameter changes on clearance flow. Our findings indicate that changing pressure-balance pipe diameter affects volumetric efficiency and pressure distribution in the upper clearance, with different mechanisms for high and low flow conditions. This study has important implications for pressure-balance pipe design. While ensuring that axial hydraulic thrust balancing is maintained, resizing the pressure-balance pipe diameter can improve unit operation efficiency.

DOI: https://doi.org/10.1088/1742-6596/2752/1/012069

Year: 2023