反转泵液力透平速度滑移机理
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摘要
速度滑移对液力透平的水力性能和内流特性有一定影响。以反转泵液力透平为研究对象,评估不同湍流模型对液力透平水力性能影响的敏感性,通过数值模拟与试验值误差分析发现,采用RNG k-ε湍流模型预测液力透平水力性能具有较高的可信度。选用RNG k-ε湍流模型和CFX17.0,分析透平内速度滑移机理及速度滑移量化指标,进一步对比液力透平和离心泵速度滑移的大小及流动机理。研究发现:液力透平叶轮内存在速度滑移现象,速度滑移导致透平水头降低,并诱发了附着于叶片工作面的旋涡。透平滑移系数随比转速变化而变化,数值在0.2～0.4。比较反转泵液力透平透平工况与泵工况的滑移系数发现:当比转速大于50时,透平工况的滑移系数比泵工况的小,比转速低于50时,出现了透平工况滑移系数高于泵工况的情形。
Slip phenomenon is known to strongly influence the performance of pumps as turbines(PAT). In the present work, the standard k-ε model,RNG k-ε model,standard k-ω and SST k-ω model are adopted to simulate the hydraulic performance of PAT, and the experiment values are in a good agreement with CFD result by using RNG k-ε model. Therefore, the slip phenomenon in turbine impeller is studied and the slip factor is estimated for each PAT using RNG k-ε model. Then the slip phenomenon in turbine mode was compared with pump mode. It is observed that slip phenomenon occurs in PAT, and it lead to the head decrease, besides, the vortex flow is generated in PAT's flow passages near pressure side of blade. The slip factor varies with the specific speed of PAT, and its value is 0.2-0.4 approximately. In comparison with pump mode, the slip factor of turbine mode smaller than pump mode when the specific speed above 50, but larger when it below 50.
Slip phenomenon is known to strongly influence the performance of pumps as turbines(PAT). In the present work, the standard k-ε model,RNG k-ε model,standard k-ω and SST k-ω model are adopted to simulate the hydraulic performance of PAT, and the experiment values are in a good agreement with CFD result by using RNG k-ε model. Therefore, the slip phenomenon in turbine impeller is studied and the slip factor is estimated for each PAT using RNG k-ε model. Then the slip phenomenon in turbine mode was compared with pump mode. It is observed that slip phenomenon occurs in PAT, and it lead to the head decrease, besides, the vortex flow is generated in PAT's flow passages near pressure side of blade. The slip factor varies with the specific speed of PAT, and its value is 0.2-0.4 approximately. In comparison with pump mode, the slip factor of turbine mode smaller than pump mode when the specific speed above 50, but larger when it below 50.
引文
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[16]刘厚林,刘东喜,王勇,等.三种空化模型在离心泵空化流动计算中的应用评价[J].农业工程学报,2012,28(16):54-59.LIU Houlin,LIU Dongxi,WANG Yong,et al.Applicative evaluation of three cavitating models on cavitating flow calculation in ce-ntrifugal pump[J].Transactions of the Chinese Society of Agricultural Engineering,2012,28(16):54-59.
[17]李晓俊,袁寿其,潘中永,等.离心泵边界层网格的实现及应用评价[J].农业工程学报,2012,28(20):67-72.LI Xiaojun,YUAN Shouqi,PAN Zhongyong.Realization and application evaluation of near-wall mesh in centrifugal pumps[J].Transactions of the Chinese Society of Agricultural Engineering,2012,28(20):67-72.
[18]谢龙汉,赵新宇.ANSYS CFX流体分析及仿真[M].北京:电子工业出版社,2013.XIE Longhan,ZHAO Xinyu.ANSYS CFX Fluid analysis and simulation[M].Beijing:Publishing House of Electronic Industry,2013.
[19]周水清,孔繁余,王志强,等.基于结构化网格的低比转速离心泵性能数值模拟[J].农业机械学报,2011,42(7):66-69.ZHOU Shuiqing,KONG Fanyu,WANG Zhiqiang,et al.Numerical simulation for low specific-speed centrifugal pump with structured grid[J].Transactions of the Chinese Society for Agricultural Machinery,2011,42(7):66-69.
[20]赵斌娟,袁寿其,陈汇龙,等.基于滑移网格研究双流道泵内非定常流动特性[J].农业工程学报,2009,25(6):115-119.ZHAO Binjuan,YUAN Shouqi,CHEN Huilong,et al.Unsteady flow characteristics in double-channel pumps based on sliding mesh[J].Transactions of the Chinese Society of Agricultural Engineering,2009,25(6):115-119.
[2]王晓晖,杨军虎,史凤霞.能量回收液力透平的研究现状及展望[J].排灌机械工程学报,2014,32(9):742-747.WANG Xiaohui.YANG Junhu,SHI Fengxia.Status and prospect of study on energy recovery hydraulic turbines[J].Journal of Drainage and Irrigation Machinery Engineering,2014,32(9):742-747.
[3]关醒凡.现代泵理论与设计[M].北京:中国宇航出版社,2011.GUAN Xingfan.Modern pumps theory and design[M].Beijing:China Astronautic Publishing House,2011.
[4]LI W G.Effects of flow rate and viscosity on slip factor of centrifugal pump handling viscous oils[J].International Journal of Rotating Machinery,2013,213(6):1-12.
[5]MEMARDEZFOULI M,NOURBAKHSH A.Experimental investigation of slip factors in centrifugal pumps[J].2009,33(5):938-945.
[6]JAIN S V,SWARNKAR A,MOTWANI K H,et al.Effects of impeller diameter and rotational speed on performance of pump running in turbine mode[J].Energy Conversion and Management,2015,89(4):808-824.
[7]GIOSIO D R,HENDERSON A D,WAIKER J M,et al.Design and performance evaluation of pump-as-turbine micro-hydro test facility with incorporated inlet flow control[J].Renewable Energy,2015,78(1):1-6.
[8]BUONO D,FROSINA E,MAZZONE A,et al.Study of a pump as turbine for a hydraulic urban network using a tridimensional CFD modeling methodogy[J].Energy Procedia,2015,82(12):201-208.
[9]YANG S S,KONG F Y,JIANG W M,et al.Effect of impeller trimming influencing pump as turbine[J].Computers&Fluids,2012,67(7):72-78.
[10]SINGH P,NEATMANN F.A consolidated model for the turbine operation of centrifugal pumps[J].Journal of Engineering for Gas Turbine and Power,2011,133(6):1-9.
[11]DERAKHSHAN S,NOURBAKHSH A.Theoretical,numerical and experimental investigation of centrifugal pumps in reverse operation[J].Experimental Thermal and Fluid Science.2008,32(8):1620-1627.
[12]ARDIZZON G,PAVESI G.Optimum incidence angle in centrifugal pumps and radial inflow turbines[J].Journal of Power and Energy,1998,212(2):97-107.
[13]VENTRONE G,ARDIZZON G,PAVESI G.Direct and reverse flow conditions in radial flow hydraulic turbomachines[J].Proceedings of the Institution of Mechanical Engineers.Part A.2000,214(A6):635-644.
[14]史广泰,杨军虎,苗森春.离心泵用作液力透平叶轮出口滑移系数的计算方法[J].农业工程学报,2014,30(13):68-77.SHI Guangtai,YANG Junhu,MIAO Senchun.Analytical methods and verification for determining slip factor at impeller outlet of centrifugal pumps as turbines[J].Transactions of the Chinese Society of Agricultural Engineering,2014,30(13):68-77.
[15]董亮,刘厚林.叶片泵CFD数值计算实例详解[M].北京:机械工业出版社,2015.DONG Liang,LIU Houlin.CFD numerical calculation examples of vans pump[M].Beijing:China Machine Press,2015.
[16]刘厚林,刘东喜,王勇,等.三种空化模型在离心泵空化流动计算中的应用评价[J].农业工程学报,2012,28(16):54-59.LIU Houlin,LIU Dongxi,WANG Yong,et al.Applicative evaluation of three cavitating models on cavitating flow calculation in ce-ntrifugal pump[J].Transactions of the Chinese Society of Agricultural Engineering,2012,28(16):54-59.
[17]李晓俊,袁寿其,潘中永,等.离心泵边界层网格的实现及应用评价[J].农业工程学报,2012,28(20):67-72.LI Xiaojun,YUAN Shouqi,PAN Zhongyong.Realization and application evaluation of near-wall mesh in centrifugal pumps[J].Transactions of the Chinese Society of Agricultural Engineering,2012,28(20):67-72.
[18]谢龙汉,赵新宇.ANSYS CFX流体分析及仿真[M].北京:电子工业出版社,2013.XIE Longhan,ZHAO Xinyu.ANSYS CFX Fluid analysis and simulation[M].Beijing:Publishing House of Electronic Industry,2013.
[19]周水清,孔繁余,王志强,等.基于结构化网格的低比转速离心泵性能数值模拟[J].农业机械学报,2011,42(7):66-69.ZHOU Shuiqing,KONG Fanyu,WANG Zhiqiang,et al.Numerical simulation for low specific-speed centrifugal pump with structured grid[J].Transactions of the Chinese Society for Agricultural Machinery,2011,42(7):66-69.
[20]赵斌娟,袁寿其,陈汇龙,等.基于滑移网格研究双流道泵内非定常流动特性[J].农业工程学报,2009,25(6):115-119.ZHAO Binjuan,YUAN Shouqi,CHEN Huilong,et al.Unsteady flow characteristics in double-channel pumps based on sliding mesh[J].Transactions of the Chinese Society of Agricultural Engineering,2009,25(6):115-119.