Internal flow and analysis of its unsteady characteristics in centrifugal pump with ultra-low specific-speed
CHEN Jie1, WANG Yong1, LIU Houlin1, SHAO Chang1, ZHANG Xiang2*
1.National Research Center of Pumps, Jiangsu University, Zhenjiang, Jiangsu 212013, China; 2.Key Laboratory of Fluid and Power Machinery, Ministry of Education, Xihua University, Chengdu, Sichuan 610039, China
Abstract：In order to explore internal flow and its unsteady characteristics in ultra-low specific-speed centrifugal pumps more comprehensively, an ultra-low specific-speed centrifugal pump with a specific-speed ns=25 was chosen as a study object. Then numerical simulations of the unsteady three-dimensional fluid flow in the pump were carried out. Finally, the internal flow field, radial thrust on the impeller and the pressure fluctuation of fluid in each section of the volute were analyzed. The results show that there appears vortices in various sizes and numbers in flow channels of the impeller under different flow conditions. A high velocity zone is found in two adjacent channels near the tongue, however, the zone disappears gradually with the increase of flow rate. Under high flow rate conditions, the area of the low velocity zone decreases gradually, the size and number of vortices reduce steadily, and the rela-tive velocity distribution in the impeller becomes uniform gradually. The orientation and magnitude of radial thrust on the impeller vary constantly, showing a hexagram pattern. The amplitude of radial thrust decreases gradually with increasing flow rate, but its main excitation frequencies are all the blade passing frequency or its integer multiples.The peak pressure fluctuation in each section of the volute decreases along the flow path and the main excitation frequencies are all the blade passing frequency or its integer multiples. This fact suggests that the impeller-volute interaction is one major factor influencing pressure fluctuation in the volute.These results have provided useful reference for optimum design of the ultra-low specific-speed centrifugal pump and selection of its feasible operating flow rate range.
陈杰, 王勇, 刘厚林, 邵昌, 张翔*. 超低比转数离心泵的内部流动及非定常特性[J]. 排灌机械工程学报, 2018, 36(5): 377-383.
CHEN Jie, WANG Yong, LIU Houlin, SHAO Chang, ZHANG Xiang*. Internal flow and analysis of its unsteady characteristics in centrifugal pump with ultra-low specific-speed. Journal of Drainage and Irrigation Machinery Engin, 2018, 36(5): 377-383.
[1]刘元义,衣振芹.超低比转速离心泵的研究[J].机械工程与自动化, 2008(2):198-200. LIU Yuanyi, YI Zhenqin. Study on super-low specific speed centrifugal pump[J]. Mechanical engineering & automation,2008(2):198-200.(in Chinese)[2]齐学义,刘永明,胡家旺,等. 提高超低比转数离心泵效率的方法[J]. 水电能源科学,2011,29(2):118-120. QI Xueyi,LIU Yongming,HU Jiawang, et al. Method of improving efficiency of low specific speed centrifugal pump[J]. Water resources and power,2011,29(2):118-120.(in Chinese)[3]马新华, 何勇冠, 陆伟刚,等. 超低比转数多级离心泵水力优化与性能试验[J]. 排灌机械工程学报,2016, 34(9):755-760. MA Xinhua,HE Yongguan,LU Weigang,et al.Hydraulic optimization and performance test of super low-specific-speed multistage centrifugal pump[J].Journal of drai-nage and irrigation machinery engineering, 2016,34(9):755-760.(in Chinese)[4]袁寿其, 王文杰, 裴吉,等. 低比转数离心泵的多目标优化设计[J]. 农业工程学报, 2015, 31(5):46-52. YUAN Shouqi, WANG Wenjie, PEI Ji, et al. Multi-objective optimization of low-specific-speed centrifugal pump[J]. Transactions of the CSAE, 2015, 31(5): 46-52.(in Chinese)[5]王洋,刘洁琼.超低比转数离心泵叶轮切割的三维流场数值模拟[J].农业机械学报,2012,43(5):79-83. WANG Yang, LIU Jieqiong. Impeller trim of super-low specific speed centrifugal pump based on numerical simu-lation of 3D flow field[J]. Transactions of the CSAM, 2012,43(5):79-83.(in Chinese)[6]邱铖, 方祥军. 带分流叶片的低比转速离心泵的特性研究[J]. 流体机械, 2017, 45(6):1-5. QIU Cheng, FANG Xiangjun. Characteristics research of a low-specific-speed centrifugal pump with splitter blades[J]. Fluid machinery, 2017, 45(6):1-5.(in Chinese)[7]WESTRA R W, BROERSMA L, ANDEL K V, et al. PIV measurements and CFD computations of secondary flow in a centrifugal pump impeller[J]. Journal of fluids engineering, 2010, 132(6):153-162.[8]杨从新,崔宗辉. 叶轮流道扩散度对超低比转数离心泵性能的影响[J]. 兰州理工大学学报, 2015, 41(6):48-53. YANG Congxin, CUI Zonghui. Effect of impeller passage expansibility on performance of centrifugal pump with ultra-low specific speed[J]. Journal of Lanzhou University of Technology, 2015, 41(6):48-53.(in Chinese)[9]崔宝玲, 方晨, 葛明亚. 低比转数离心泵内部流动特性和外特性试验[J]. 排灌机械工程学报, 2016,34(5):375-380. CUI Baoling, FANG Chen, GE Mingya. Internal flow characteristics and performance test of low specific-speed centrifugal pumps[J]. Journal of drainage and irrigation machinery engineering,2016,34(5):375-380.(in Chinese)[10]BRAUN O. Part load flow in radial centrifugal pumps[M]. [S.l.]: Epfl, 2009.[11]马皓晨, 丁荣, 杨东升. 低比转数离心泵驼峰现象的 CFD 分析[J]. 流体机械, 2013,41(12):43-47. MA Haochen,DING Rong,YANG Dongsheng. CFD research on hump phenomenon of low specific speed centrifugal pump[J]. Fluid machinery, 2013, 41(12):43-47.(in Chinese)[12]SANO T, YOSHIDA Y, TSUJIMOTO Y, et al. Numerical study of rotating stall in a pump vaned diffuser[J]. Journal of fluids engineering,2002,124(2):192-201.[13]MENTER F R. Two-equation eddy-viscosity turbulence models for engineering applications[J]. AIAA journal,1994,32(8):1598-1605.[14]MENTER F R. Zonal two-equation k-ω turbulence model for aerodynamic flows[J].AIAA journal,1993,31(9):1993-2006.[15]MENTER F R,KUNTZ M,LANGTRY R. Ten years of industrial experience with the SST turbulence model[J]. Turbulence, heat and mass transfer, 2003, 4(1):625-632.
