PIV experimental study on unsteady internal flow field in low-specific-speed sewage pump
Wang Zhen1, Chen Bin2, Zhang Hua3, Hu Qixiang3, Gao Biao2
1.Nanjing Lanshen Pump Co. Ltd., Nanjing, Jiangsu 211500, China; 2.Research Institute of Chemical Machinery, Hefei University of Technology, Hefei, Anhui 230009, China; 3.National Research Center of Pumps, Jiangsu University, Zhenjiang, Jiangsu 212013, China
Abstract:Through modifying the structure of a traditional electromechanical integrated sewage pump, the test pump sector suitable for PIV measurement was obtained with plexiglas as impeller and volute material and with half-spiral suction chamber for changing flow direction. To shoot the flow field on the middle section of impeller at five different relative positions of impeller and volute under three different conditions, synchronous device as shaft encoder was adopted with hollow glassy microspheres acting as tracer particle, and fine results were finally achieved.From PIV measurement results, the internal flow field shows good axisymmetrical distributions at any time under conditions of 1.4Qd and 1.0Qd, while at extremely small flow rate 0.2Qd, the internal flow field becomes disordered and presents obvious non-axisymmetry. For passage A at five shooting moments, as it passes through the location of volute tongue, the relative velocity distribution gradient on outlet circumference as well as the strength and dimension of vortex at small flow rate are all subject to the intense interference of tongue. As for passage C, at extremely small flow rate, flow separation near pressure surface is intensifying to form vortex blocking most of the passage.
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