Particle image velocimetry measurement of flow fields in a mixed-flow pump with non-uniform tip clearance
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R E G UL A R P A P E R
Wei Li • Leilei Ji • Weidong Shi • Enda Li • Zhenyu Yang
Particle image velocimetry measurement of flow fields in a mixed-flow pump with non-uniform tip clearance
Received: 3 June 2019 / Revised: 16 January 2020 / Accepted: 14 February 2020 Ó The Visualization Society of Japan 2020
Abstract In order to better understand the flow characteristics of mixed-flow pump with non-uniform tip clearance, a test rig is established and the flow fields of various cross section in impeller are studied based on particle image velocimetry technology. The velocity vector distributions of three cross sections, e.g., impeller blade inlet, middle and outlet, were measured. The influences of flow rate and eccentricity on the flow fields of mixed-flow pump with non-uniform tip clearance were analyzed, and the relative velocity distribution of different positions at the same cross section is quantitatively discussed. The results show that the external characteristics have been greatly affected by the eccentricity of impeller. There is a significant negative correlation between eccentricity and efficiency. The maximum head and efficiency drop of eccentric impeller reach 11% and 20% separately. With the increase in eccentricity, the secondary flow phenomenon increases, such as backflow and vortex flow in impeller flow passage. Vortex structure is easily formed in the end wall region, which will give rise to backflow and even blocks the flow passage near impeller hub. The energy loss increases continuously in this process which is the main reason for the significant drop in efficiency. The research results are instructive for revealing the flow characteristics of flow fields of mixed-flow pump with non-uniform tip clearance. Keywords Mixed-flow Pump Particle image velocimetry (PIV) Non-uniform tip Vortex
1 Introduction Mixed-flow pumps widely used in many fields and play an important role in the national economic construction, such as agricultural irrigation and drainage, urban water supply and drainage, large-scale water conservancy projects, seawater desalination systems, circulating water system and nuclear power plants for thermal power generation (Chen et al. 2019; Lei et al. 2017; Li et al. 2019; Yang et al. 2019; Ji et al. 2017). Due to the material unevenness and poor quality control of assembly or manufacturing, the mass eccentricity of the rotor exists in mixed-flow pump operation inevitably. Eccentricity causes uneven distribution of the W. Li (&) L. Ji (&) E. Li Z. Yang National Research Center of Pumps, Jiangsu University, No. 301, Xuefu Road, Jingkou District, Zhenjiang 212013, Jiangsu, China E-mail: [email protected] L. Ji E-mail: [email protected] W. Li Institute of Fluid Engineering Equipment Technology, JITRI, Jiangsu University, Zhenjiang 212009, Jiangsu, China W. Shi College of Mechanical Engineering, Nantong University, Nantong 226019, China
W. Li et al.
flow fields in the gap of impeller and then leads to shaft system imbalances of mixed-flow pump at high speed (Li e
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