水泵水轮机全流道“S”特性区数值分析
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摘要
抽水蓄能电站在水电中扮演着极其重要的角色,其机组水泵水轮机的"S"特性区流动情况是研究的重点。以自主研发的某水泵水轮机为研究对象,根据模型试验结果的"S"特性曲线,选取其中小导叶开度的"S"特性曲线,结合SST k-w湍流模型,运用ANSYS-CFX软件对曲线上部分工况点进行了数值分析。数值分析工况包括水轮机工况、飞逸工况、制动工况和反水泵工况,通过计算得到了单位流量和单位转速的关系曲线,所得曲线与模型试验曲线较为吻合。计算结果表明:在制动工况和反水泵工况时,固定导叶、活动导叶和转轮区域内均存在较多的旋涡性回流,为较为不稳定的工况。转轮区域内流动速度极低,叶片中间位置有无规则性回流,相邻的两个叶片头部之间形成横向流动的水环,水环在离心力的作用下阻挡水流进入流道,从而大大减小了转轮的过流能力,这可能是导致水泵水轮机在制动工况下单位转速降低的重要原因。
Pumped storage power stations play an important role in hydropower. The flow condition in "S" characteristics zone of pump-turbine is an important research issue in hydraulic machinery industry. Taking a self-developed pump-turbine as the research object, based on "S" characteristics curve from model test and selecting the "S" characteristics curve with small openings, we analyzed some partial operation points on the curve by ANSYS-CRX software and turbulent flow model. The numerical analysis operation cases included turbine condition, runaway condition, braking condition and reverse pump condition. The relation curve of unit discharge and unit rotating speed were obtained, and they were in good agreement with model test curve. The analysis results showed that in braking and reverse pump cases, vortex back flow existed in the zones of stationary blade, moving blade and runner, which were unstable. The flow velocity in runner zone was very low. The irregular back flow existed in the middle of the blade, and the transversal flow-ring formed in the zone between two blade heads, which would resist flow entering flow channel under the action of centrifugal force and greatly reduce the flow capacity of runner. This may be the important cause of unit rotating speed falling of pump-turbine under braking condition.
Pumped storage power stations play an important role in hydropower. The flow condition in "S" characteristics zone of pump-turbine is an important research issue in hydraulic machinery industry. Taking a self-developed pump-turbine as the research object, based on "S" characteristics curve from model test and selecting the "S" characteristics curve with small openings, we analyzed some partial operation points on the curve by ANSYS-CRX software and turbulent flow model. The numerical analysis operation cases included turbine condition, runaway condition, braking condition and reverse pump condition. The relation curve of unit discharge and unit rotating speed were obtained, and they were in good agreement with model test curve. The analysis results showed that in braking and reverse pump cases, vortex back flow existed in the zones of stationary blade, moving blade and runner, which were unstable. The flow velocity in runner zone was very low. The irregular back flow existed in the middle of the blade, and the transversal flow-ring formed in the zone between two blade heads, which would resist flow entering flow channel under the action of centrifugal force and greatly reduce the flow capacity of runner. This may be the important cause of unit rotating speed falling of pump-turbine under braking condition.
引文
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[14] 王乐勤,刘锦涛,梁成,等.水泵水轮机水轮机制动区的流动特性[J].排灌机械工程学报,2011,29(1):1-5.
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[18] 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):39-44.
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[20] 纪兴英.水泵水轮机“S”特性预测方法研究[D].武汉:武汉大学,2013.
[2] 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,2013.
[3] 梅祖彦.抽水蓄能技术[M].北京:水利水电出版社,1993.
[4] 曹鹍,姚志明.水轮机原理及水力设计[M].北京:清华大学出版社,1991.
[5] 杨琳,陈乃祥.水力机械转轮三维反问题研究及其新进展[J].水力发电学报,2004,23(1):97-101.
[6] 杨国颖,冯琛然.基于逆向设计理论的水泵水轮机设计与数值模拟[J].排灌机械工程学报,2013,31(11):964-968.
[7] 王旭鹤,祝宝山,曹树良,等.可逆式水泵水轮机转轮的三维反问题优化设计[J].农业工程学报,2014,30(13):78-85.
[8] Sallaberger M,Bachmann P,Michaud C,et al.Modern hydraulic design of large pump-turbine[J].International Journal on Hydropower & Dams,2003,10(5):112-118.
[9] Kerschberger P,Gehrer A.Hydraulic development of high specific-speed pump-turbines by means of an inverse design method,numerical flow-simulation(CFD) and model testing[C]//Proceedings of 25th IAHR Symposium on Hydraulic Machines and Systems,Timisoara,Romania,2010:012039
[10] 吕文娟.非同步导叶对混流式水泵水轮机“S”特性影响研究[D].兰州:兰州理工大学,2014
[11] 杨琳,陈乃祥.水泵水轮机转轮全特性与蓄能电站过渡过程的相关性分析[J].清华大学学报(自然科学版),2003,43(10):1424-1427.
[12] 纪兴英,赖旭.低比转速水泵水轮机“S”区特性数值模拟[J].水动力学研究与进展,2011,26(3):318-326.
[13] 李仁年,刘殿兴,董志强,等.水泵水轮机“S”形区全流道数值模拟[J].排灌机械工程学报,2013,31(5):401-405.
[14] 王乐勤,刘锦涛,梁成,等.水泵水轮机水轮机制动区的流动特性[J].排灌机械工程学报,2011,29(1):1-5.
[15] Yin J L,Liu J T,Wang L Q,et al.Performance prediction and flow analysis in the vaned distributor of a pump turbine under flow rate in pump mode[J].Science China-Technological Sciences,2010,53(12):3302-3309.
[16] Menter F R,Kuntz M,Langtry R.Ten Years of Industrial Experience with the SST Turbulence Mode[J].Turbulence,Heat and Mass Transfer,2003(4):1-8.
[17] Cummings R M,Forsythe J R,Morton S A,et al.Computational challenges in high angle of attack flow prediction[J].Progress in Aerospace Sciences,2003(39):369-384.
[18] 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):39-44.
[19] Wang L Q,Yin J L,Jiao L,et al.Numerical investigation on the "S" characteristics of a reduced pump turbine model[J].Science China-Technological Sciences,2011(54):1-8.
[20] 纪兴英.水泵水轮机“S”特性预测方法研究[D].武汉:武汉大学,2013.
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