Investigation of hydraulic losses in different clocking positions of pump-turbine in pump mode

Abstract

With the increasing significance of pumped storage in the power system, there is a growing emphasis on improving the hydraulic performance of pump-turbine at pump mode. Consequently, this study aims to investigate the clocking effects of the stay vane and guide vane in order to enhance hydraulic performance. Moreover, the local hydraulic loss rate method is employed to visualize the loss distribution of each component. The results demonstrate that the clocking effect significantly impacts off-design conditions. Specifically, for different clocking positions of the stay vane, the maximum efficiency difference at 0.8Qd and 1.2Qd conditions is 0.14 % and 0.86 % respectively. Similarly, for the guide vane, the values are 0.54 % and 0.34 % respectively. Furthermore, different clocking schemes result in significant changes in hydraulic losses in the volute and stay vane. For the 0.8Qd condition, the hydraulic losses inside the impeller and guide vanes vary significantly with the change in the velocity gradient at the impeller outlet. The optimal clocking effect position for the guide vanes occurs when the trailing edge and the tongue are aligned, and similarly, the position for the stay vanes is when the tongue is located at the 2/3 point of the stay vane flow passage. The study can provide a theoretical guiding significance for structural optimization and installation position of pump-turbine.