Internal flow characteristics of centrifugal pump at low flow rates
Fu Yanxia1,2, Yuan Shouqi1, Yuan Jianping1, Fu Yuedeng3, Huang Ping1
1.National Research Center of Pumps, Jiangsu University, Zhenjiang, Jiangsu 212013, China; 2.Civil and Industrial Engineering Department, University of Pisa, Pisa, Toscana 56121, Italy; 3.New United Group, Changzhou, Jiangsu 213011, China
In order to investigate the performance and internal flow characteristics of centrifugal pump at low flow rates, the type IS160-50-65 end-suction centrifugal pump was selected as computational model. The three-dimensional, steady, turbulent, incompressible fluid flow in the whole pump including a suction pipe, impeller and volute was simulated by means of software Ansys CFX 12.0. Meanwhile the grid independence was checked by employing three sets of mesh to improve the computational accuracy. Finally, both the performance and internal flow characteristics of the pump at low flow rates were analyzed with the mesh just determined. It was shown that the predicted pump head, total efficiency are deviated from the experimental data by 1.47% and 3.61% only under the design condition. As the flow rate is decreased, the predicted head is closer to the tested one to some extent; unfortunately, the estimated efficiency shows increasing disagreement with the experimental value. In addition, the internal flow is quite uniform under the design condition. At low flow rates, however, there is a recirculation in the suction pipe; a reverse flow occurs in the impeller passages as well. The reverse flow is so dominated that it can occupy the entire impeller passages at a certainly low flow rate. At an extreme low flow rate, say 20% design flow rate, the recirculation flow has extended into the whole suction pipe.
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