Influence of guide vane opening on water-ring flow characteristics of pump-turbine in synchronous condenser mode
LIU Dianhai1, ZHU Baoshan2, CHEN Shuai3, CHEN Zhenmu4*, ZHANG Fei1
1. Pumped-storage Technological and Economic Research Institute, State Grid Xinyuan Company Ltd., Beijing 100761, China; 2. Department of Energy and Power Engineering, Tsinghua University, Beijing 10084, China; 3. Chongqing Panlong Pumped Storage Co., Ltd., Chongqing 401420, China; 4. Department of Mechanical and Electrical Engineering, Wenzhou University, Wenzhou, Zhejiang 32500, China
Abstract：It is necessary to inject air into the runner passage to reduce the starting power, when pump turbine operates under the starting process in pump mode or under the synchronous condenser mode. In order to prevent the compressed air in the runner passage from leaking into the casing, it is necessary to form a certain thickness of water-ring in the vaneless space for sealing to reduce the air consumption. In order to investigate the water-ring characteristics of pump-turbine in synchronous condenser mode by different guide vane openings, the ANSYS CFX software was employed to conduct the unsteady state analysis with two-phase flow. The pump-turbine model was adopted to investigate the internal flow characteristics on the water-ring with three guide vane openings(full closed, 1% GVO, 2% GVO). The research shows that the thickness of the water-ring increases with decrease in guide vane opening, which results in increasing the resistance of the runner and the consumption of the shaft power. At the same time, the dominate frequency of pressure fluctuation in the vaneless space is the blade pass frequency and harmonics, which represents the phenomenon of rotor-stator interaction obviously. The research results can provide a reference for controlling water-ring of pump-turbine in the process of synchronous condenser mode and sump start-up mode.
