Abstract:In order to investigate flow separations at partload conditions in centrifugal pumps, twodimensional laser doppler velocimetry was successfully applied to a low specific speed radial diffuser pump to precisely measure unsteady flow fields at four partload conditions (0.75Qd, 0.50Qd, 0.40Qd and 0.30Qd) in the impeller. Based on measurements, the phaseaveraged velocity field and turbulence intensity field were obtained for each measuring point. The analysis of the measurements shows that there is no flow separation at 0.75Qd. However, a twochannel flow separation was observed in the impeller at 0.50Qd, 0.40Qd and 0.30Qd: the amounts of flow separation were quite different between two adjacent flow channels. However, the flow separations exhibit a periodicity of 120°, possibly due to the blade number ratio between impeller blades and diffuser vanes (6∶9). Furthermore, the velocity components and turbulence intensity were analyzed and compared among all four operating points. The results show that turbulence intensity increases as flow rate decreases. The highest turbulence intensity near the impeller outlet is 0.06 (based on u2) at 0.75Qd, and the highest one reaches about 0.12-0.14 at operating points 0.50Qd, 0.40Qd and 0.30Qd.
冯建军, 武桦, 罗兴锜, 卢金玲. 基于LDV的离心泵小流量工况内流场测量[J]. 排灌机械工程学报, 2013, 31(2): 109-112.
FENG Jian-Jun, WU Hua, LUO Xing-Qi, LU Jin-Ling. Measurements of internal flow in centrifugal pump at partload conditions based on LDV. Journal of Drainage and Irrigation Machinery Engin, 2013, 31(2): 109-112.
[1]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):363-370.[2]Sinha M, Pinarbasi A, Katz J. The flow structure during onset and developed states of rotating stall within a vaned diffuser of a centrifugal pump [J]. Journal of Fluids Engineering, 2001, 123(3):490-499.[3]Wang H, Tsukamoto H. Experimental and numerical study of unsteady flow in a diffuser pump at off design conditions [J]. Journal of Fluids Engineering, 2003, 125(5):767-778.[4]Buffaz N, Trébinjac I. Detailed analysis of the flow in the inducer of a transonic centrifugal compressor[J].Journal of Thermal Science, 2012, 21(1):1-12.[5]Bulot N, Trébinjac I, Ottavy X, et al. Experimental and numerical investigation of the flow field in a highpressure centrifugal compressor impeller near surge[J]. Proceedings of the Institution of Mechanical Engineers:Part A, 2009, 223(6): 657-666.[6]Hobson G V, Caruso T M, Carlson J R. Threecomponent LDV measurements in the wake of a compressor cascade with flow separation [J]. J Turbomach, 2008, 130(1):1-8.[7]Matsunuma T. Unsteady flow field of an axialflow turbine rotor at a low Reynolds number [J]. J Turbomach, 2007, 129(2):360-371.[8]Pintrand G, Caignaert G, Bois G, et al. Analysis of unsteady flows in a vaned diffuser radial flow pump [C]//Proceedings of the XXIst IAHR Symposium on Hydraulic Machinery and Systems, 2002.[9]Nicholas P, Larsen P S, Jacobsen C B. Flow in a centrifugal pump impeller at design and offdesign conditions—Part I: Particle image velocimetry (PIV) and laser doppler velocimetry (LDV) measurements [J]. Journal Fluids Engineering, 2003, 125(1):61-72.[10]Akhras A, Hajem M E, Champagne J Y, et al.The flow rate influence on the interaction of a radial pump impeller and the diffuser [J]. Int J Rotating Mach, 2004, 10(4):309-317.[11]刘正先, 王永, 曹淑珍, 等. 非设计工况下离心泵叶轮内湍流场的LDV测量[J]. 航空动力学报, 2004, 19(4):449-454.Liu Zhengxian, Wang Yong, Cao Shuzhen, et al. LDV measurements of turbulent flow field in a centrifugal impeller at offdesign flow [J]. Journal of aerospace power, 2004, 19(4):449-454. (in Chinese)[12]李文广, 薛敦松, 余龙. 离心泵蜗壳内部清水流动测量[J]. 甘肃工业大学学报, 2001, 27(4): 40-43.Li Wenguang, Xue Dunsong, Yu Long. Measurements of water flow in centrifugal pump volute [J]. Journal of Gansu University of Technology, 2001, 27(4):40-43.(in Chinese)