To study the hydraulic instability of a pumpturbine at the pump mode under different working conditions, the threedimensional, unsteady flow in the whole passage of the pumpturbine was conducted by using computational fluid dynamics softwareFluent under the optimal, low and high flow rate conditions. The pressure fluctuations were monitored respectively at the inlet of spiral casing, in the interface of runner and guide vanes, and in the space between head cover and runner, as well as in draft tube. The results show that a larger pressure fluctuation can be found in the interface of runner and guide vanes and in the space between the runner and head cover, while the pressure fluctuation is lower at the inlet of the spiral casing and in the draft tube. The pressure fluctuation is the smallest under the optimal condition; the larger the working condition deviates from the optimal one, the more considerable the fluctuation is. The dominant frequency of pressure fluctuation depends on the locations monitored. The dominant frequencies are integer multiples of the blade passing frequency and the runner rotational frequency in the interface of runner and guide vanes and in the space between runner and head cover, respectively. However, the dominant frequencies of the pressure fluctuation at the inlet of the spiral casing and in the draft tube are mainly related to lowfrequency components.
WANG Le-Qin,LIU Ying-Yuan,LIU Wan-Jiang et al. Pressure fluctuation characteristics of pumpturbine at pump mode[J]. Journal of Drainage and Irrigation Machinery Engin, 2013, 31(1): 7-10.
Ran Hongjuan, Luo Xianwu, Zhu Lei, et al. Experimental study of the pressure fluctuations in a pump turbine at large partial flow conditions [J]. Chinese Journal of Mechanical Engineering, 2012, 25:1205-1209.
Vlad Hasmatuchi, Mohamed Farhat, Pierre Maruzewski, et al. Experimental investigation of a pumpturbine at offdesign operating conditions [C]／／Proceedings of the 3rd IAHR International Meeting of the Workgroup on Cavitation and Dynastic Problems in Hydraulic Machinery and Systems. Brno(Czech Republic): Brno University of Technology, 2009:339-347.
Zhang Lanjin, Wang Zhengwei, Chang Jinshi. Flow of pumpturbine on Sshaped region of complete characteristic [J]. Transactions of the Chinese Society for Agricultural Machinery, 2011, 42(1): 39-43. (in Chinese)
Yin Junlian, Liu Jintao, Wang Leqin. Prediction of pressure fluctuations of pump turbine under offdesign condition in pump mode [J]. Journal of Engineering Thermophysics, 2011, 32(7): 1141-1144. (in Chinese)
Wu Shangfeng, Wu Yulin, Lin Lin, et al. 3D unsteady turbulent flow simulation and pressure fluctuation prediction on the axial flow turbine [J]. Journal of Engineering Thermophysics, 2006,27(6):956-958. (in Chinese)
Wang Leqin, Liu Jintao, Zhang Lefu, et al. Low flow′s fluctuation characteristics in pumpturbine′s pump mode [J]. Journal of Zhejiang University:Engineering Science, 2011, 45(7): 1239-1243. (in Chinese)
Yin Junlian, Liu Jintao, Wang Leqin, et al. Performance prediction and flow analysis in the vaned distributor of a pump turbine under low flow rate in pump mode [J]. Science China:Technological Sciences, 2010, 53(12): 3302-3309.