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| Characteristics of pressure fluctuation in pump-turbine in turbine mode |
| QIAN Zhongdong, LU Jie, GUO Zhiwei, ZHANG Jianjun |
| State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan, Hubei 430072, China |
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Abstract In order to investigate the pressure fluctuation characteristics of pump-turbine in turbine mode, a three-dimensional unsteady flow in a pump-turbine is numerically simulated using the shear stress transport(SST)k-ω turbulence model. By comparing computational flow discharge and efficiency with experimental ones, the flow models are validated. The pressure fluctuations in the guide vanes, runner and draft tube under three different operational conditions are analyzed, respectively. The results show that both the shape and the rotating direction of vortex rope have an obvious influence on the pressure fluctuation. At a low discharge, vortex rope is helical and has the same rotating direction with the runner, a severe low-frequency pressure fluctuation appears at the runner outlet. The frequency of pressure fluctuation on the runner blade is about 0.62 times the runner rotational frequency and the dominant frequency in the draft tube is about 0.36 times the runner rotational frequency. At an optimum and large discharge, the vortex rope is tubular, the amplitude of pressure fluctuation at the runner outlet is reduced. The dominant frequency of the pressure fluctuation in the draft tube is the same as the frequency of pressure fluctuation on the runner blade. At a large discharge, the vortex rope is in the inverse rotating direction of the runner, and the maximal amplitude in the pressure fluctuation in the draft tube appears at the tube elbow.
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Received: 16 November 2015
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| [1]OLIMSTAD G, NIELSEN T, BØRRESEN B. Stability limits of reversible-pump turbines in turbine mode of operation and measurements of unstable characteristics[J]. Journal of fluids engineering, 2012, 134(11): 1-8.[2]胡旭光. 水泵水轮机不稳定性运行的初步探讨[J]. 水电站机电技术, 2001(2): 18-20. HU Xuguang. Study on instability operation of pump-turbine[J]. Mechanical & electrical technique of hydropower station, 2001(2):18-20.(in Chinese)[3]STAUBLI T, SENN F, SALLABERGER M. Instability of pump-turbines during start-up in the turbine mode[R/OL]. [2015-11-16]. http://www.researchgate.net/publication/237241545.[4]钱忠东, 李万. 泄水锥形式对混流式水轮机压力脉动的影响分析[J]. 水力发电学报, 2012, 31(5):278-285,291. QIAN Zhongdong, LI Wan. Analysis of pressure oscillation characteristics in Francis hydraulic turbine with different runner cones[J]. Journal of hydroelectric engineering, 2012, 31(5):278-285,291.(in Chinese)[5]李仁年,蒋雷,李琪飞,等. 水泵水轮机增负荷过程尾水管内流场分析[J]. 灌排机械工程学报, 2015, 33(1):49-54. LI Rennian, JIANG Lei, LI Qifei, et al. Analysis of flow field in draft tube of pump-turbine during load increasing period[J]. Journal of drainage and irrigation machinery engineering, 2015,33(1):49-54.(in Chinese)[6]ZOBEIRI A. Investigations of time dependent flow phenomena in a turbine and a pump-turbine of Francis type: rotor-stator interactions and processing vortex rope[J/OL]. EPFL Doctoral Thesis, 2009. [2015-11-16]. http://infoscience.epfl.ch/record/128887. DOI: 10.5075/epfl-thesis-4272.[7]SUN Yuekun, ZUO Zhigang, LIU Shuhong, et al. Numerical study of pressure fluctuations transfer law in different flow rate of turbine mode in a prototype pump turbine[C]//Proceedings of IOP Conference Series: Materials Science and Engineering. [S.l.]: IOP Publis-hing, 2013,52(5): 1-7.[8]杨建东,曾威,杨威嘉,等. 水泵水轮机飞逸稳定性及其与反S特性曲线的关联[J].农业机械学报, 2015,46(4):59-64. YANG Jiandong, ZENG Wei, YANG Weijia, et al. Runaway stabilities of pump-turbines and its correlations with S characteristic curves[J]. Transactions of the CSAM, 2015,46(4):59-64.(in Chinese)[9]HASMATUCHI V, FARHAT M, MARUZEWSKI P, et al. Experimental investigation of a pump-turbine at off-design operating conditions[C]//Proceedings of 3rd IAHR International meeting of the workgroup on cavitation and dynamic problems in hydraulic machinery and systems. Brno, Czech Republic: [s.n.], 2009: 339-347.[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(6): 1205-1209.[11]GUO Lei, LIU Jintao, WANG Leqin, et al. Pressure fluctuation propagation of a pump turbine at pump mode under low head condition[J]. Science China technological sciences, 2014,57(4): 811-818.[12]XIAO Yexiang, WANG Zhengwei, ZHANG Jin, et al. Numerical predictions of pressure pulses in a Francis pump turbine with misaligned guide vanes[J]. Journal of hydrodynamics, 2014,26(2): 250-256.[13]KIRSCHNER O, RUPRECHT A, GÖDE E, et al. Experimental investigation of pressure fluctuations caused by a vortex rope in a draft tube[C]//Proceedings of IOP Conference Series: Earth and Environmental Science. [S.l.]: IOP Publishing, 2012,15(6):1-8.[14]QIAN Zhongdong, ZHENG Biao, HUAI Wenxin, et al. Analysis of pressure oscillations in a Francis hydraulic turbine with misaligned guide vanes[J]. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of power and energy, 2010,224(1):139-152.[15]WANG Zhengwei, ZHOU Lingjiu. Simulations and measurements of pressure oscillations caused by vortex ropes[J]. Journal of fluids engineering.2006, 128(4): 649-655. |
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