活动导叶分布圆直径对混流式水轮机水力性能的影响
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摘要
对于混流式水轮机,活动导叶与固定导叶以及转轮的相对位置直接影响导水机构和转轮内部流动,对水轮机安全、稳定、高效运行起到重要作用。采用商业软件ANSYS CFX 16. 0对某电站水轮机模型机全流道进行三维数值模拟计算,提出了5种活动导叶分布圆直径方案,分析不同方案下水轮机的外部能量特性与内部流场,寻找活动导叶安放的最佳位置。结果表明:适当增大活动导叶分布圆直径,可以有效改善叶片吸力面的低压区,降低活动导叶流域内水流的最大速度,改善转轮进口水流角,同时减小导水机构与转轮的水力损失。小流量工况下,D_0/D_1增大0. 031,水轮机效率提高了5. 28个百分点;设计工况与大流量工况下,活动导叶分布圆的变化对水轮机效率的影响相对于小流量工况较小,最高效率与最低效率的差值分别为0. 17%与0. 48%。因此,在一定范围内改变活动导叶的分布圆直径具有可实施性,对水轮机的优化设计有一定参考价值。
For a Francis turbine,the movable guide vane is mainly used to regulate the flow rate and circulation,the relative positions of guide vane,stay vane and the runner directly affect the internal flow of water guiding mechanism and runner,which play an important role in the safe,stable and efficient operation of the turbine. The commercial software ANSYS CFX 16. 0 was used to calculate the threedimensional steady flow in the full flow channel of a hydraulic turbine model machine. Five guide vane distribution circle diameter schemes were proposed to be analyzed,aiming at obtaining the energy characteristics and internal flow fields of the turbine under different schemes. Then the best position of the active vane placement was determined,and the results showed that by appropriately increasing the circular diameter of the guide vane distribution,the low-pressure area at the suction surface of the blade could be improved,the maximum flow velocity around guide vanes could also be reduced,the flow angle at the inlet of the runner was more reasonable,and the hydraulic losses of the guide mechanism and the runner were decreased,and the turbine operating efficiency was improved. At low flow rates,D_0/D_1( guide vane distribution circle diameter/runner diameter) was increased by 0. 031,and the turbine corresponding efficiency was increased by 5. 28 percentage points,at designing flow rate or high ones,the influence of change of guide vane distribution on the turbine efficiency was smaller than that at low flow rates. Compared with the different circle diameter schemes of guide vane,the difference between the highest efficiency and the lowest efficiency were 0. 17% under the design condition and 0. 48% at the high flow one,respectively. Therefore,changing the distribution circle diameter of the guide vane within a certain range had the engineering practicability in the capacity-increasing projects of the water-power station units,which can be applied in optimizing the Francis turbine.
For a Francis turbine,the movable guide vane is mainly used to regulate the flow rate and circulation,the relative positions of guide vane,stay vane and the runner directly affect the internal flow of water guiding mechanism and runner,which play an important role in the safe,stable and efficient operation of the turbine. The commercial software ANSYS CFX 16. 0 was used to calculate the threedimensional steady flow in the full flow channel of a hydraulic turbine model machine. Five guide vane distribution circle diameter schemes were proposed to be analyzed,aiming at obtaining the energy characteristics and internal flow fields of the turbine under different schemes. Then the best position of the active vane placement was determined,and the results showed that by appropriately increasing the circular diameter of the guide vane distribution,the low-pressure area at the suction surface of the blade could be improved,the maximum flow velocity around guide vanes could also be reduced,the flow angle at the inlet of the runner was more reasonable,and the hydraulic losses of the guide mechanism and the runner were decreased,and the turbine operating efficiency was improved. At low flow rates,D_0/D_1( guide vane distribution circle diameter/runner diameter) was increased by 0. 031,and the turbine corresponding efficiency was increased by 5. 28 percentage points,at designing flow rate or high ones,the influence of change of guide vane distribution on the turbine efficiency was smaller than that at low flow rates. Compared with the different circle diameter schemes of guide vane,the difference between the highest efficiency and the lowest efficiency were 0. 17% under the design condition and 0. 48% at the high flow one,respectively. Therefore,changing the distribution circle diameter of the guide vane within a certain range had the engineering practicability in the capacity-increasing projects of the water-power station units,which can be applied in optimizing the Francis turbine.
引文
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[12]高忠信,唐澍,梁贺志.水轮机固定导叶和活动导叶后的卡门涡频率研究[J].水动力学研究与进展(A辑),2005,20(6):729-735.GAO Zhongxin,TANG Shu,LIANG Hezhi.Study on Karman vortices after stay vane and guide vane for hydropower station[J].Journal of Hydrodynamics(A),2005,20(6):729-735.(in Chinese)
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[14]ANUP K C,LEE Y H,THAPA B.CFD study on prediction of vortex shedding in draft tube of Francis turbine and vortex control techniques[J].Renewable Energy,2016,86(2):1406-1421.
[15]黄剑峰,张立翔,杨松,等.水轮机活动导叶关闭过程中导水机构内动态流场数值模拟研究[J].水利学报,2017,48(3):299-307.HUANG Jianfeng,ZHANG Lixiang,YANG Song,et al.Numerical simulation of dynamic flow around wicket gate in hydro turbine with guide vane closure[J].Journal of Hydraulic Engineering,2017,48(3):299-307.(in Chinese)
[16]郭涛,张立翔.混流式水轮机小开度下导水机构内湍流特性和叶道涡结构研究[J].工程力学,2015,32(6):222-230.GUO Tao,ZHANG Lixiang.Numerical study on turbulence characteristics in Francis turbine under small opening condition[J].Engineering Mechanics,2015,32(6):222-230.(in Chinese)
[17]LI Qifei,QUAN Hui,LI Rennian,et al.Influences of guide vanes airfoil on hydraulic turbine runner performance[C]∥2012International Conference on Modern Hydraulic Engineering,2012:703-708.
[18]PEREIRAS B,VALDEZ P,CASTRO F.Numerical analysis of a unidirectional axial turbine for twin turbine configuration[J].Applied Ocean Research,2014,47(8):1-8.
[19]THAPA B S,TRIVEDI C,DAHLHAUG O G.Design and development of guide vane cascade for a low speed number Francis turbine[J].Journal of Hydrodynamics,Ser.B,2016,28(4):676-689.
[20]朱国俊,罗兴锜,冯建军,等.混流式水轮机转轮设计变量耦合强度分析[J].农业工程学报,2017,33(22):36-45.ZHU Guojun,LUO Xingqi,FENG Jianjun,et al.Variable coupling strength analysis of Francis turbine runner design[J].Transactions of the CSAE,2017,33(22):36-45.(in Chinese)
[21]TYAGI R K.The effect of an angle on the impact and flow quantity on output power of an impulse water wheel model[J].Journal of Energy in Southern Africa,2015,26(3):100-104.
[22]刘晶石,吕桂萍,钟苏,等.基于ANSYS的轴流式水轮机空心活动导叶结构优化分析[J].水力发电学报,2014,33(6):215-219.LIU Jingshi,LGuiping,ZHONG Su,et al.Optimization of hollow wicket gate of Kaplan turbine based on ANSYS[J].Journal of Hydroelectric Engineering,2014,33(6):215-219.(in Chinese)
[23]LI Qifei,LI Rennian,QUAN Hui,et al.Solid-liquid two-phase flow numerical simulation around guide vanes of mixed-flow water turbine[C]∥International Conference on Advances in Computational Modeling and Simulation,2012:87-91.
[24]任岩,张兰金,李延频,等.水轮机的磨蚀失效特性[J].排灌机械工程学报,2012,30(2):188-191.REN Yan,ZHANG Lanjin,LI Yanpin,et al.Sand abrasion characteristics of materials for hydro-turbines[J].Journal of Drainage and Irrigation Machinery Engineering,2012,30(2):188-191.(in Chinese)
[25]CHITRAKAR S,NEOPANE H P,DAHLHAUG O G.Study of the simultaneous effects of secondary flow and sediment erosion in Francis turbines[J].Renewable Energy,2016,97(11):881-891.
[26]CHOI H J,ZULLAH M A,ROH H W,et al.CFD validation of performance improvement of a 500 k W Francis turbine[J].Renewable Energy,2013,54(6):111-123.
[27]冯建军,李文峰,席强,等.混流式水轮机主轴中心孔补水对尾水管性能的影响[J].农业工程学报,2017,33(3):58-64.FENG Jianjun,LI Wenfeng,XI Qiang,et al.Influence of water admission through main shaft central hole on performance of Francis turbine draft tube[J].Transactions of CSAE,2017,33(3):58-64.(in Chinese)
[28]CAMPOBASSO M S,YAN M,BONFIGLIOLI A,et al.Low-speed preconditioning for strongly coupled integration of Reynoldsaveraged Navier-Stokes equations and two-equation turbulence models[J].Aerospace Science and Technology,2018,77(6):286-298.
[29]毛秀丽,李春华,屈波,等.蜗壳轴向出流式低比转数水轮机设计与数值模拟[J/OL].农业机械学报,2018,49(5):204-211.MAO Xiuli,LI Chunhua,QU Bo,et al.Design and numerical simulation of volute axial outflow hydraulic turbine with low specific speed[J/OL].Transactions of the Chinese Society for Agricultural Machinery,2018,49(5):204-211.http:∥www.j-csam.org/jcsam/ch/reader/view_abstract.aspx?flag=1&file_no=20180523&journal_id=jcsam.DOI:10.6041/j.issn.1000-1298.2018.05.023.(in Chinese)
[30]冯静安,唐小琦,王卫兵,等.基于网格无关性与时间独立性的数值模拟可靠性的验证方法[J].石河子大学学报(自然科学版),2017,35(1):52-56.FENG Jing'an,TANG Xiaoqi,WANG Weibing,et al.Reliability verification method of numerical simulation based on grid independence and time independence[J].Journal of Shihezi University(Natural Science),2017,35(1):52-56.(in Chinese)
[31]张金凤,黄茜,袁寿其,等.基于PIV的低比转数离心泵网格无关性[J].排灌机械工程学报,2016,34(7):567-572,583.ZHANG Jinfeng,HUANG Xi,YUAN Shouqi,et al.Grid-independence in low specific speed centrifugal pump based on PIV[J].Journal of Drainage and Irrigation Machinery Engineering,2016,34(7):567-572,583.(in Chinese)
[32]刘万江,魏显著,韩秀丽,等.高水头混流式水轮机导叶位置关系对水力性能的影响[J].大电机技术,2013(6):46-48,51.LIU Wanjiang,WEI Xianzhu,HAN Xiuli,et al.Influence of the relational position of guide vanes on the hydraulic performance in high-head Francis turbine[J].Large Electric Machine and Hydraulic Turbine,2013(6):46-48,51.(in Chinese)
[2]MALIPEDDI A R,CHATTERJEE D.Influence of duct geometry on the performance of Darrieus hydroturbine[J].Renewable Energy,2012,43:292-300.
[3]TIMOSHEVSKIY M V,CHURKIN S A,KRAVTSOVA A Y,et al.Cavitating flow around a scaled-down model of guide vanes of a high-pressure turbine[J].International Journal of Multiphase Flow,2016,78(1):75-87.
[4]HAN Wei,WANG Jie,KANG Jingbo,et al.Erosion characteristics of hydraulic turbine guide-vane end clearance in sediment water flow:a simplified model analysis[J].Journal of Flow Control,Measurement&Visualization,2017,5(10):111-126.
[5]KRZEMIANOWSKI Z,PUZYREWSKI R.3D computations of flow field in a guide vane blading designed by means of 2D model for a low head hydraulic turbine[C]∥Journal of Physics:Conference Series,2014.
[6]GAVRILOV A A,SENTYABOV A V,DEKTEREV A A,et al.Vortical structures and pressure pulsations in draft tube of a Francis-99 turbine at part load:RANS and hybrid RANS/LES analysis[J].International Journal of Heat and Fluid Flow,2017,63(6):158-171.
[7]ROMERO-GOMEZ P,HARDING S F,RICHMOND M C.The effects of sampling location and turbulence on discharge estimates in short converging turbine intakes[J].Engineering Applications of Computational Fluid Mechanics,2017,11(1):513-525.
[8]MUIS A,SUTIKNO P,SOEWONO A,et al.Design optimization of axial hydraulic turbine for very low head application[C]∥2nd International Conference on Sustainable Energy Engineering and Application,ICSEEA,Energy Procedia,2015:263-273.
[9]KOIRALA R,THAPA B,NEOPANE H P,et al.A review on flow and sediment erosion in guide vanes of Francis turbines[J].Renewable and Sustainable Energy Reviews,2017,75(8):1054-1065.
[10]NEGRU R,MUNTEAN S,MARSAVINA L,et al.Computation of stress distribution in a Francis turbine runner induced by fluid flow[J].Computational Materials Science,2012,64(11):253-259.
[11]SILVA P A S F,DE OLIVEIRA T F,BRASIL A C P,et al.Numerical study of wake characteristics in a horizontal-axis hydrokinetic turbine[J].Anais da Academia Brasileira de Ciencias,2016,88(4):2441-2456.
[12]高忠信,唐澍,梁贺志.水轮机固定导叶和活动导叶后的卡门涡频率研究[J].水动力学研究与进展(A辑),2005,20(6):729-735.GAO Zhongxin,TANG Shu,LIANG Hezhi.Study on Karman vortices after stay vane and guide vane for hydropower station[J].Journal of Hydrodynamics(A),2005,20(6):729-735.(in Chinese)
[13]LI S C.Tiny bubbles challenge giant turbines:three Gorges puzzle[J/OL].Interface Focus,2015,5(5).https:∥doi.org/10.1098/rsfs.2015.0020.
[14]ANUP K C,LEE Y H,THAPA B.CFD study on prediction of vortex shedding in draft tube of Francis turbine and vortex control techniques[J].Renewable Energy,2016,86(2):1406-1421.
[15]黄剑峰,张立翔,杨松,等.水轮机活动导叶关闭过程中导水机构内动态流场数值模拟研究[J].水利学报,2017,48(3):299-307.HUANG Jianfeng,ZHANG Lixiang,YANG Song,et al.Numerical simulation of dynamic flow around wicket gate in hydro turbine with guide vane closure[J].Journal of Hydraulic Engineering,2017,48(3):299-307.(in Chinese)
[16]郭涛,张立翔.混流式水轮机小开度下导水机构内湍流特性和叶道涡结构研究[J].工程力学,2015,32(6):222-230.GUO Tao,ZHANG Lixiang.Numerical study on turbulence characteristics in Francis turbine under small opening condition[J].Engineering Mechanics,2015,32(6):222-230.(in Chinese)
[17]LI Qifei,QUAN Hui,LI Rennian,et al.Influences of guide vanes airfoil on hydraulic turbine runner performance[C]∥2012International Conference on Modern Hydraulic Engineering,2012:703-708.
[18]PEREIRAS B,VALDEZ P,CASTRO F.Numerical analysis of a unidirectional axial turbine for twin turbine configuration[J].Applied Ocean Research,2014,47(8):1-8.
[19]THAPA B S,TRIVEDI C,DAHLHAUG O G.Design and development of guide vane cascade for a low speed number Francis turbine[J].Journal of Hydrodynamics,Ser.B,2016,28(4):676-689.
[20]朱国俊,罗兴锜,冯建军,等.混流式水轮机转轮设计变量耦合强度分析[J].农业工程学报,2017,33(22):36-45.ZHU Guojun,LUO Xingqi,FENG Jianjun,et al.Variable coupling strength analysis of Francis turbine runner design[J].Transactions of the CSAE,2017,33(22):36-45.(in Chinese)
[21]TYAGI R K.The effect of an angle on the impact and flow quantity on output power of an impulse water wheel model[J].Journal of Energy in Southern Africa,2015,26(3):100-104.
[22]刘晶石,吕桂萍,钟苏,等.基于ANSYS的轴流式水轮机空心活动导叶结构优化分析[J].水力发电学报,2014,33(6):215-219.LIU Jingshi,LGuiping,ZHONG Su,et al.Optimization of hollow wicket gate of Kaplan turbine based on ANSYS[J].Journal of Hydroelectric Engineering,2014,33(6):215-219.(in Chinese)
[23]LI Qifei,LI Rennian,QUAN Hui,et al.Solid-liquid two-phase flow numerical simulation around guide vanes of mixed-flow water turbine[C]∥International Conference on Advances in Computational Modeling and Simulation,2012:87-91.
[24]任岩,张兰金,李延频,等.水轮机的磨蚀失效特性[J].排灌机械工程学报,2012,30(2):188-191.REN Yan,ZHANG Lanjin,LI Yanpin,et al.Sand abrasion characteristics of materials for hydro-turbines[J].Journal of Drainage and Irrigation Machinery Engineering,2012,30(2):188-191.(in Chinese)
[25]CHITRAKAR S,NEOPANE H P,DAHLHAUG O G.Study of the simultaneous effects of secondary flow and sediment erosion in Francis turbines[J].Renewable Energy,2016,97(11):881-891.
[26]CHOI H J,ZULLAH M A,ROH H W,et al.CFD validation of performance improvement of a 500 k W Francis turbine[J].Renewable Energy,2013,54(6):111-123.
[27]冯建军,李文峰,席强,等.混流式水轮机主轴中心孔补水对尾水管性能的影响[J].农业工程学报,2017,33(3):58-64.FENG Jianjun,LI Wenfeng,XI Qiang,et al.Influence of water admission through main shaft central hole on performance of Francis turbine draft tube[J].Transactions of CSAE,2017,33(3):58-64.(in Chinese)
[28]CAMPOBASSO M S,YAN M,BONFIGLIOLI A,et al.Low-speed preconditioning for strongly coupled integration of Reynoldsaveraged Navier-Stokes equations and two-equation turbulence models[J].Aerospace Science and Technology,2018,77(6):286-298.
[29]毛秀丽,李春华,屈波,等.蜗壳轴向出流式低比转数水轮机设计与数值模拟[J/OL].农业机械学报,2018,49(5):204-211.MAO Xiuli,LI Chunhua,QU Bo,et al.Design and numerical simulation of volute axial outflow hydraulic turbine with low specific speed[J/OL].Transactions of the Chinese Society for Agricultural Machinery,2018,49(5):204-211.http:∥www.j-csam.org/jcsam/ch/reader/view_abstract.aspx?flag=1&file_no=20180523&journal_id=jcsam.DOI:10.6041/j.issn.1000-1298.2018.05.023.(in Chinese)
[30]冯静安,唐小琦,王卫兵,等.基于网格无关性与时间独立性的数值模拟可靠性的验证方法[J].石河子大学学报(自然科学版),2017,35(1):52-56.FENG Jing'an,TANG Xiaoqi,WANG Weibing,et al.Reliability verification method of numerical simulation based on grid independence and time independence[J].Journal of Shihezi University(Natural Science),2017,35(1):52-56.(in Chinese)
[31]张金凤,黄茜,袁寿其,等.基于PIV的低比转数离心泵网格无关性[J].排灌机械工程学报,2016,34(7):567-572,583.ZHANG Jinfeng,HUANG Xi,YUAN Shouqi,et al.Grid-independence in low specific speed centrifugal pump based on PIV[J].Journal of Drainage and Irrigation Machinery Engineering,2016,34(7):567-572,583.(in Chinese)
[32]刘万江,魏显著,韩秀丽,等.高水头混流式水轮机导叶位置关系对水力性能的影响[J].大电机技术,2013(6):46-48,51.LIU Wanjiang,WEI Xianzhu,HAN Xiuli,et al.Influence of the relational position of guide vanes on the hydraulic performance in high-head Francis turbine[J].Large Electric Machine and Hydraulic Turbine,2013(6):46-48,51.(in Chinese)