水泵水轮机飞逸工况下尾水管涡带演化研究
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摘要
为研究水泵水轮机在飞逸工况下不同导叶开度时的水力不稳定性,以某抽水蓄能电站水泵水轮机为研究对象,基于Realizable k-ε湍流模型的非定常数值计算方法,对水泵水轮机七种不同导叶开度下的流动进行全流道计算。结合监测蜗壳进口、无叶区、转轮与顶盖之间以及尾水管处的压力脉动,研究了水泵水轮机在不同导叶开度下尾水管涡带的形态,及其对尾水管压力脉动的影响。结果表明:飞逸工况下,尾水管涡带与开导叶度关系密切;小开度下,涡带较明显且涡带形态不断撕裂重构并伴有局部回流;随开度增大,尾水管涡带的形态逐渐由紊乱无规则变为明显锥状,且随着开度的进一步增大涡带形状演变为粗壮螺旋涡带。大开度下,涡带近壁面旋向侧速度较大是导致直锥段壁面湍动能较大等能量损失的主要原因;尾水管涡带不断向下游输运,是造成水泵水轮机尾水管巨大压力脉动的关键因素。
To study the hydraulic instability of pump-turbine under runaway condition with different guide vane openings, the pump-turbine of a certain pumped storage power station was employed. Based on the Realizable k-ε turbulent model, the unsteady flow of the whole passage of the pump-turbine with seven different guide vane openings was calculated. The pressure fluctuation of the inlet of the volute, blade free section, the region between the runner and the roof, and draft tube was monitored to study the evolution of vortex shape and pressure fluctuation on the draft tube with the effects on different guide vane opening. Results show that when the guide vane opening is different under runaway condition, there is a distinct difference of the shape of the vortex. In the small guide vane opening, the vortex is obvious and the shape of the vortex changes constantly. With the increase of the guide vane opening, the shape of the vortex tends to the pattern of geometric cone from the disordered status, as well as the screw vortex rope presents the thicker tendency gradually. In the large guide vane opening, the higher velocity distribution near the vortex rope wall leads to the great loss of turbulent kinetic energy and other forms of energy near the straight cone region. Meanwhile, the key reason why great pressure fluctuation is caused in the draft tube is that the vortex is transported continuously towards the downstream.
To study the hydraulic instability of pump-turbine under runaway condition with different guide vane openings, the pump-turbine of a certain pumped storage power station was employed. Based on the Realizable k-ε turbulent model, the unsteady flow of the whole passage of the pump-turbine with seven different guide vane openings was calculated. The pressure fluctuation of the inlet of the volute, blade free section, the region between the runner and the roof, and draft tube was monitored to study the evolution of vortex shape and pressure fluctuation on the draft tube with the effects on different guide vane opening. Results show that when the guide vane opening is different under runaway condition, there is a distinct difference of the shape of the vortex. In the small guide vane opening, the vortex is obvious and the shape of the vortex changes constantly. With the increase of the guide vane opening, the shape of the vortex tends to the pattern of geometric cone from the disordered status, as well as the screw vortex rope presents the thicker tendency gradually. In the large guide vane opening, the higher velocity distribution near the vortex rope wall leads to the great loss of turbulent kinetic energy and other forms of energy near the straight cone region. Meanwhile, the key reason why great pressure fluctuation is caused in the draft tube is that the vortex is transported continuously towards the downstream.
引文
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[19]刘超.部分负荷工况下水泵水轮机空化流动特性研究[D].兰州:兰州理工大学,2016.
[20]窦国仁.紊流力学:上册[M].北京:人民教育出版社,1981.
[21]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].排灌机械工程学报,2015,33(1):50-54.LI Rennian,JIAGN Lei,LI Qifei,et al.Analysis of flow field in draft tube of pump turbine during load increasing process[J].Journal of the Drainage and Irrigation Machinery Engineering,2015,33(1):50-54.
[2]马震岳.水轮发电机组动力学[M].大连:大连理工大学出版社,2003.
[3]FAVEY H T,CASSIDY J J.Frequency and amplitude of pressure generated by swirling flow[C]∥Proceedings of IAHR 5th Symposium.Stockholm:IAHR,1970.
[4]Tacob,刘诗琪.混流式水轮机脉动的探讨和数据处理[J].国外大电机,1998(3):60-67.TACOB,LIU Shiqi.Discussion and data processing of Francis turbine pulsation[J].Foreign Large Motor,1998(3):60-67.
[5]ALLIGNE S,NICOLET C,TSUJIMOTO Y,et al.Cavitation surge modelling in Francis turbine draft tube[J].Journal of Hydraulic Research,2014,52(3):399-411.
[6]吴钢,韦彩新,谭月灿,等.导叶开口对混流水轮机尾水管压力脉动的影响[J].华中科技大学学报(自然科学版),1999(9):27-29.WU Gang,WEI Caixin,TAN Yuecan,et al.The effect of gatage on the pressure fluctuation in draft tube of francis turbine[J].Journal of Huazhong University of Science and Technology(Natural Science),1999(9):27-29.
[7]KONSTANTINOV A,STAROSELSKY I,ORSZAG S A,et al.Renormalization group-based transport modeling of premixed turbulent combustion:I.incompressible deflagration model[J].Journal of Scientific Computing,1998,13(3):229-252.
[8]KURENKOV A,OBERLACK M.Modelling turbulent premixed combustion using the level set approach for reynolds averaged models[J].Flow Turbulence & Combustion,2005,74(4):387-407.
[9]张春泽,刁伟,尤建锋,等.长短叶片水轮机尾水涡带动态特性数值分析[J].华中科技大学学报(自然科学版),2017,45(7):66-73.ZHANG Chunze,DIAO Wei,YOU Jianfeng,et al.Numerical analysis of dynamic characteristics of the vortex rope in a francis turbine with splitter blades[J].Journal of Huazhong University of Science and Technology(Natural Science),2017,45(7):66-73.
[10]高忠信,邓杰,葛新峰.三维非定常湍流尾水管涡带数值模拟[J].水利学报,2009,40(10):1162-1167.GAO Zhongxin,DENG Jie,GE Xinfeng.Numerical simulation of three-dimensional unsteady vortex rope turbulent flow occurred to the draft tube of a Francis turbine[J].Journal of Hydraulic Engineering,2009,40(10):1162-1167.
[11]王乐勤,刘锦涛,张乐福,等.水泵水轮机泵工况小流量波动特性[J].浙江大学学报(工学版),2011,845(7):1239-1243.WANG Leqin,LIU Jintao,ZHANG Lefu,et al.Small flow fluctuation characteristics of pump-turbine’pump mode[J].Journal of Zhejiang University(Engineering Science),2011,845(7):1239-1243.
[12]王乐勤,刘迎圆,刘万江,等.水泵水轮机泵工况的压力脉动特性[J].排灌机械工程学报,2013,31(1):7-10.WANG Leqin,LIU Yingyuan,LIU Wanjiang,et al.Pressure pulsation characteristics of pump turbine operating conditions[J].Journal of the Drainage and Irrigation Machinery Engineering,2013,31(1):7-10.
[13]谭海燕.水泵水轮机水轮机工况压力脉动数值分析[D].兰州:兰州理工大学,2015.
[14]NICOLET C,ZOBEIRI A,MARUZEWSKI P,et al.On the upper part load vortex rope in Francis turbine:experimental investigation[C]∥Iop Conference Series Earth&Environmental Science.[S.l.]:ICSEES,2010.
[15]尹俊连.水泵水轮机“S”区内流机理及优化设计研究[D].杭州:浙江大学,2012.
[16]杨静.混流式水轮机尾水管空化流场研究[D].北京:中国农业大学,2013.
[17]张兰金,王正伟,常近时.混流式水泵水轮机全特性曲线S形区流动特性[J].农业机械学报,2011,42(1):39-43.ZHANG Lanjin,WANG Zhengwei,CHANG Jinshi.Flow characteristics of S flow in full characteristic curve of Francis pump turbine[J].Proceedings of the Chinese Society of Agricultural Mechanization,2011,42(1):39-43.
[18]MENTER F R,MENTER F.Two-equation eddy-viscosity transport turbulence model for engineering applications[J].AIAA Journal,1994,32(8):1598-1605.
[19]刘超.部分负荷工况下水泵水轮机空化流动特性研究[D].兰州:兰州理工大学,2016.
[20]窦国仁.紊流力学:上册[M].北京:人民教育出版社,1981.
[21]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].排灌机械工程学报,2015,33(1):50-54.LI Rennian,JIAGN Lei,LI Qifei,et al.Analysis of flow field in draft tube of pump turbine during load increasing process[J].Journal of the Drainage and Irrigation Machinery Engineering,2015,33(1):50-54.