轴流泵叶轮导水锥型式设计及其流道水力特性模拟
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摘要
为探究轴流泵叶轮导水锥的设计方法,揭示导水锥流场的内部流动特性。基于三维不可压缩流体的雷诺平均N-S方程和k-ε湍流模型,结合典型的收缩曲线,设计了维多辛斯基式、五次方曲线式、双三次方曲线式等5种导水锥。利用Fluent软件对各型导水锥进行三维流场计算,分析了导水锥流道的流动特性,归纳了导水锥流场的3个流动部分以及流场轴面的速度分布规律。总结了轴向速度分布均匀度、加权平均偏流角随导水锥收缩型面的变化规律。分析各型导水锥水力损失发现:不同型式导水锥水力损失不同,直锥式导水锥损失略小,其他型式的导水锥水力损失相近。对流场均匀性相比较得出:在导水锥流场急剧收缩的断面上,轴向速度分布均匀度降低,速度加权平均偏流角和径向速度梯度增大。导水锥出口段收缩越平缓,整流能力越出色。综合考虑轴向速度均匀度和速度偏流角等指标,维多辛斯基式导水锥的整流能力最优,出口流场均匀性较好。当导水锥长度为叶轮外径的0.25~0.8倍时,导水锥长度增加,水力损失减小,导水锥出口流场品质提升。结合工程实际应用,给出导水锥长度最优取值范围为叶轮外径的0.5~0.6倍。
Axial flow pumps have advantages of large capacity and low head and the impeller is an important component of axial-flow pump. Guide cone is usually installed on the top of impeller and its appropriate design can enhance flow quality of pump inlet, lower turbulivity, make velocity steady, and so on. To meet with engineering demands, find feasible design and investigate the internal flow characteristics of guide cone, we designed different types of guide cones installed on the impeller. Based on three dimensional incompressible Navier-Stokes equation and k-ε turbulent model, SIMPLEC algorithm was applied to solve a discretization governing equation, five different types of guide cones were designed with contraction curves such as Witozinsky, Bicubic, Fifth degree polynomial curves. The CFD method was used to simulate 3D flow field of guide cone. In order to verify the feasibility of simulation models, the guide cones were installed on the impeller and the simulated head and efficiency values were obtained using simulation method same as the flow field simulation of guide cone. Meanwhile, a laboratory test was performed on a DN200 test bench to measure the pumping head, discharge, and other parameters for calculation of head and efficiency. Results showed that the simulated and measured head and efficiency had relative error less than 4%, indicating the feasibility of the simulation method for flow field simulation of guide cones. Simulation on flow velocity of guide cones suggested three flow processes: 1) flow velocity is even in inlet passage and slightly increased; 2) the flow velocity starts to increase and change its direction in contraction passage of guide cone flow field; and 3) the flow field contraction becomes slow in the outlet passage of guide cone. Hydraulic loss of different guide cones varied. The head loss of circular cone was lower than the others. In the sharp contraction cross section of guide cone passage, the uniformity of axial velocity distribution was low, but the velocity weighted average drift angle and radial velocity gradient was high. The rectification capability was better when the contraction at outlet section of guide cone flow field was slow and gentle. Taking into account of uniformity of axial velocity, velocity weighted average drift angle, and the others, the guide cone based on Witozinsky curve had the best rectification capacity and better flow field uniformity. When the length of guide cone was 0.25-0.8 times as impeller diameter, increasing cone length could decrease the hydraulic loss and velocity weighted average drift angle, and improve flow field quality of cone. The results above in combination with practical application, we suggested that the optimal length of the guide cone was 0.5-0.6 times as impeller diameter. This study is helpful to design hydraulic models of high-efficient axial-flow pumps.
Axial flow pumps have advantages of large capacity and low head and the impeller is an important component of axial-flow pump. Guide cone is usually installed on the top of impeller and its appropriate design can enhance flow quality of pump inlet, lower turbulivity, make velocity steady, and so on. To meet with engineering demands, find feasible design and investigate the internal flow characteristics of guide cone, we designed different types of guide cones installed on the impeller. Based on three dimensional incompressible Navier-Stokes equation and k-ε turbulent model, SIMPLEC algorithm was applied to solve a discretization governing equation, five different types of guide cones were designed with contraction curves such as Witozinsky, Bicubic, Fifth degree polynomial curves. The CFD method was used to simulate 3D flow field of guide cone. In order to verify the feasibility of simulation models, the guide cones were installed on the impeller and the simulated head and efficiency values were obtained using simulation method same as the flow field simulation of guide cone. Meanwhile, a laboratory test was performed on a DN200 test bench to measure the pumping head, discharge, and other parameters for calculation of head and efficiency. Results showed that the simulated and measured head and efficiency had relative error less than 4%, indicating the feasibility of the simulation method for flow field simulation of guide cones. Simulation on flow velocity of guide cones suggested three flow processes: 1) flow velocity is even in inlet passage and slightly increased; 2) the flow velocity starts to increase and change its direction in contraction passage of guide cone flow field; and 3) the flow field contraction becomes slow in the outlet passage of guide cone. Hydraulic loss of different guide cones varied. The head loss of circular cone was lower than the others. In the sharp contraction cross section of guide cone passage, the uniformity of axial velocity distribution was low, but the velocity weighted average drift angle and radial velocity gradient was high. The rectification capability was better when the contraction at outlet section of guide cone flow field was slow and gentle. Taking into account of uniformity of axial velocity, velocity weighted average drift angle, and the others, the guide cone based on Witozinsky curve had the best rectification capacity and better flow field uniformity. When the length of guide cone was 0.25-0.8 times as impeller diameter, increasing cone length could decrease the hydraulic loss and velocity weighted average drift angle, and improve flow field quality of cone. The results above in combination with practical application, we suggested that the optimal length of the guide cone was 0.5-0.6 times as impeller diameter. This study is helpful to design hydraulic models of high-efficient axial-flow pumps.
引文
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abstract)
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[9]Tokyay T E,Constantinescu S G,Asce M.Validation of a large-eddy simulation model to simulate flow in pump intakes of realistic geometry[J].Journal of Hydraulic Engineering,2006,132(12):1303-1315.
[10]徐磊,陆林广,陈伟,等.竖井贯流泵装置水力设计方案比较研究[J].水力发电学报,2011,30(5):207-215.Xu Lei,Lu Linguang,Chen Wei,et al.Study on comparison of hydraulic design schemes for shaft tubular pump system[J].Hydroelectric Engineering,2011,30(5):207-215.(in Chinese with English abstract)
[11]徐磊,陆林广,陈伟,等.南水北调工程邳州泵站竖井贯流泵装置进出水流态分析[J].农业工程学报,2012,28(6):50-56.Xu Lei,Lu Linguang,Chen Wei,et al.Flow pattern analysis on inlet and outlet conduit of shaft tubular pump system of Pizhou pumping station in South-to-North Water Diversion Project[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2012,28(6):50-56.(in Chinese with English abstract)
[12]朱红耕,张仁田,冯旭松,等.不同型式贯流泵装置结构特点与水力特性研究[J].灌溉排水学报,2009,28(5):58-60. Zhu Honggeng,Zhang Rentian,Feng Xusong,et al.Structural features and hydraulic performances analysis ofvarious tubular pumping systems[J].Journal of Irrigation nand Drainage,2009,28(5):58-60.(in Chinese with English abstract)
[13]朱红耕,戴龙洋,张仁田,等.新型竖井贯流泵装置研发与数值模拟[J].排灌机械工程学报,2011,29(5):418-422.Zhu Honggeng,Dai Longxiang,Zhang Rentian,et al.Development and numerical analysis of new-type shaft tubular pumping system[J].Drainage and Irrigation Machinery Engineering,2011,29(5):418-422.(in Chinese with English abstract)
[14]成立,刘超,汤方平,等.基于RNG紊流模型的立式轴流泵站三维流动数值模拟及性能预测[J].机械工程学报,2009,45(3):252-257.Cheng Li,Liu Chao,Tang Fangping,et al.3D numerical simulation and performance predication of vertical axial flow pumping station by RNG turbulent model[J].Journal of Mechanical Engineering,2009,45(3):252-257.(in Chinese with English abstract)
[15]成立,刘超,周济人,等.大型立式泵站双向进水流道三维紊流数值模拟[J].农业机械学报,2004,35(3):61-64.Cheng Li,Liu Chao,Zhou Jiren,et al.Numerical simulation of three-dimensional flow inside suction box of reversible pumping station[J].Transactions of the Chinese Society for Agricultural Machinery,2004,35(3):61-64.(in Chinese with English abstract)
[16]成立,刘超,汤方平,等.大型立式泵站簸箕型进水流道三维紊流数值模拟[J].水力发电学报,2004,23(4):65-68.Cheng Li,Liu Chao,Tang Fangping,et al.Numericalsimulation of three-dimensional turbulent flow of dust-pan shaped box for pumping station[J].Journal of Hydroelectric Engineering,2004,23(4):65-68.(in Chinese with English abstract)
[17]徐磊,陆林广,陈伟,等.竖井贯流泵装置水力设计方案比较研究[J].水力发电学报,2011,30(5):207-215.Xu Lei,Lu Linguang,Chen Wei,et al.Study on comparison of hydraulic design schemes for shaft tubular pump system[J].Hydroelectric Engineering,2011,30(5):207-215.(in Chinese with English abstract)
[18]徐磊,陆林广,陈伟,等.南水北调工程邳州泵站竖井贯流泵装置进出水流态分析[J].农业工程学报,2012,28(6):50-56.Xu Lei,Lu Linguang,Chen Wei,et al.Flow pattern analysis on inlet and outlet conduit of shaft tubular pump system of Pizhou pumping station in South-to-North Water Diversion Project[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2012,28(6):50-56.(in Chinese with English abstract)
[19]徐磊,陆林广,陈伟,等.邳州泵站竖井贯流泵装置模型试验研究[J].灌溉排水学报,2012,32(2):121-123.Xu Lei,Lu Linguang,Chen Wei,et al.Model test for pit tubular pump system of Pi-Zhou pump station[J].Journal of Irrigation and Drainage,2012,32(2):121-123.(in Chinese with English abstract)
[20]中国人民解放军总装备部军事训练敎材编辑工作委员会.高低速风洞气动与结构设计[M].北京:国防工业出版社,2003:66.
[21]韩占忠.Fluent-流体工程仿真计算实例与分析[M].北京:北京理工大学出版社,2009:45-53.
[22]王福军.计算流体动力学分析:CFD软件原理与应用[M].北京:清华大学出版社,2004.
[23]陆林广,张仁田.泵站进水流道优化水力设计[M].北京:中国水利水电出版社,1997:18-19.
[2]朱红耕,袁寿其,刘厚林.肘形进水流道对立式轴流泵水力性能影响的数值模[J].农业工程学报,2006,22(2):6-9.Zhu Honggeng,Yuan Shouqi,Liu Houlin.Numerical simulation of the influence of elbow inlet passages on the hydraulic characteristics of vertical axial-flow pumps[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2006,22(2):6-9.(in Chinese with English abstract)
[3]杨帆,刘超,汤方平,等.大型立式轴流泵装置流道内部流动特性分析[J].农业机械学报,2011,42(5):39-43,55.Yang Fan,Liu Chao,Tang Fangping,et al.Characteritics of flow in large vertical axial flow pumping system[J].Transactions of the Chinese Society for Agricultural Machinery,2011,42(5):39-43,55.(in Chinese with English abstract)
[4]杨帆,罗祝北,汤方平,等.大型低扬程泵站钟型进水流道水力特性研究[J].中国农村水利水电,2011,2:135-138.
[5]杨帆,刘超,汤方平,等.箱涵式进水流道的立式轴流泵装置水动力特性分析[J].农业工程学报,2014,30(4):62-70.Yang Fan,Liu Chao,Tang Fangping,et al.Analysis of hydraulic performance for vertical axial-flow pumping system with cube-type inlet passage[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2014,30(4):62-70.(in Chinese with English
abstract)
[6]Tang Xue lin,Wang Fu jun,Li Yaojun,et al.Numerical investigations of vortex flows and vortex suppression schemes in a large pumping-station sump[J].Proceedings of the Institution of Mechanical Engineers,Part C:Journal of Mechanical Engineering Science,2011,225(6):1459-1480.
[7]Ahmad Z,Jain B,Kumar S,et al.Rational design of a pump-sump and its model testing[J].Journal of Pipeline Systems Engineering and Practice,2010,2(2):53-63.
[8]Wang Zhengwei,Peng Guangjie,Zhou Lingjiu,et al.Hydraulic performance of a large slanted axial-flow pump[J].Engineering Computations,2010,27(2):243-256.
[9]Tokyay T E,Constantinescu S G,Asce M.Validation of a large-eddy simulation model to simulate flow in pump intakes of realistic geometry[J].Journal of Hydraulic Engineering,2006,132(12):1303-1315.
[10]徐磊,陆林广,陈伟,等.竖井贯流泵装置水力设计方案比较研究[J].水力发电学报,2011,30(5):207-215.Xu Lei,Lu Linguang,Chen Wei,et al.Study on comparison of hydraulic design schemes for shaft tubular pump system[J].Hydroelectric Engineering,2011,30(5):207-215.(in Chinese with English abstract)
[11]徐磊,陆林广,陈伟,等.南水北调工程邳州泵站竖井贯流泵装置进出水流态分析[J].农业工程学报,2012,28(6):50-56.Xu Lei,Lu Linguang,Chen Wei,et al.Flow pattern analysis on inlet and outlet conduit of shaft tubular pump system of Pizhou pumping station in South-to-North Water Diversion Project[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2012,28(6):50-56.(in Chinese with English abstract)
[12]朱红耕,张仁田,冯旭松,等.不同型式贯流泵装置结构特点与水力特性研究[J].灌溉排水学报,2009,28(5):58-60. Zhu Honggeng,Zhang Rentian,Feng Xusong,et al.Structural features and hydraulic performances analysis ofvarious tubular pumping systems[J].Journal of Irrigation nand Drainage,2009,28(5):58-60.(in Chinese with English abstract)
[13]朱红耕,戴龙洋,张仁田,等.新型竖井贯流泵装置研发与数值模拟[J].排灌机械工程学报,2011,29(5):418-422.Zhu Honggeng,Dai Longxiang,Zhang Rentian,et al.Development and numerical analysis of new-type shaft tubular pumping system[J].Drainage and Irrigation Machinery Engineering,2011,29(5):418-422.(in Chinese with English abstract)
[14]成立,刘超,汤方平,等.基于RNG紊流模型的立式轴流泵站三维流动数值模拟及性能预测[J].机械工程学报,2009,45(3):252-257.Cheng Li,Liu Chao,Tang Fangping,et al.3D numerical simulation and performance predication of vertical axial flow pumping station by RNG turbulent model[J].Journal of Mechanical Engineering,2009,45(3):252-257.(in Chinese with English abstract)
[15]成立,刘超,周济人,等.大型立式泵站双向进水流道三维紊流数值模拟[J].农业机械学报,2004,35(3):61-64.Cheng Li,Liu Chao,Zhou Jiren,et al.Numerical simulation of three-dimensional flow inside suction box of reversible pumping station[J].Transactions of the Chinese Society for Agricultural Machinery,2004,35(3):61-64.(in Chinese with English abstract)
[16]成立,刘超,汤方平,等.大型立式泵站簸箕型进水流道三维紊流数值模拟[J].水力发电学报,2004,23(4):65-68.Cheng Li,Liu Chao,Tang Fangping,et al.Numericalsimulation of three-dimensional turbulent flow of dust-pan shaped box for pumping station[J].Journal of Hydroelectric Engineering,2004,23(4):65-68.(in Chinese with English abstract)
[17]徐磊,陆林广,陈伟,等.竖井贯流泵装置水力设计方案比较研究[J].水力发电学报,2011,30(5):207-215.Xu Lei,Lu Linguang,Chen Wei,et al.Study on comparison of hydraulic design schemes for shaft tubular pump system[J].Hydroelectric Engineering,2011,30(5):207-215.(in Chinese with English abstract)
[18]徐磊,陆林广,陈伟,等.南水北调工程邳州泵站竖井贯流泵装置进出水流态分析[J].农业工程学报,2012,28(6):50-56.Xu Lei,Lu Linguang,Chen Wei,et al.Flow pattern analysis on inlet and outlet conduit of shaft tubular pump system of Pizhou pumping station in South-to-North Water Diversion Project[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2012,28(6):50-56.(in Chinese with English abstract)
[19]徐磊,陆林广,陈伟,等.邳州泵站竖井贯流泵装置模型试验研究[J].灌溉排水学报,2012,32(2):121-123.Xu Lei,Lu Linguang,Chen Wei,et al.Model test for pit tubular pump system of Pi-Zhou pump station[J].Journal of Irrigation and Drainage,2012,32(2):121-123.(in Chinese with English abstract)
[20]中国人民解放军总装备部军事训练敎材编辑工作委员会.高低速风洞气动与结构设计[M].北京:国防工业出版社,2003:66.
[21]韩占忠.Fluent-流体工程仿真计算实例与分析[M].北京:北京理工大学出版社,2009:45-53.
[22]王福军.计算流体动力学分析:CFD软件原理与应用[M].北京:清华大学出版社,2004.
[23]陆林广,张仁田.泵站进水流道优化水力设计[M].北京:中国水利水电出版社,1997:18-19.