Simulation Of The Flow Field And Optimization For Multistage Centrifugal Pump

The multistage centrifugal pump is composed of more than two pumps with the same function,and it has the advantages of safe and stable operation,long service life,convenient installation and maintenance,etc.The impeller and guide vane are all very important components for a multistage centrifugal pump,which directly affects its own performance.Therefore,in the thesis,the D(P)450-60 type of multistage centrifugal pump is taken as the research object and the internal flow field and structural optimization are analyzed based on the CFD technology.The purpose of the thesis is to improve the performance of multistage pump and reduce the energy consumption.The thesis mainly contains the following points:(1)The 3D channel model is built according to the two-dimensional drawing of the multistage centrifugal pump and the model is meshed based on the unstructured grids technology.According to the CFD analysis,the distribution and hydraulic performance of various components of the internal flow field under rated conditions and non rated conditions are predicted by taking use of Fluent software and it is found that the guide vane is the main energy loss component of the pump.Then,partial performance tests for the multistage centrifugal pump are completed according to its test standard.The correctness of the model and the rationality of the simulation method are verified by the comparison between the experimental and predicted values,which lays the foundation for the flow field analysis and optimized design.(2)Based on the internal flow field’s analysis of the guide vane,it is found that the inlet angle,return guide vane’s inlet angle,diameter and axial width are the major geometric parameters influencing the guide vane.The ranges of these four geometric parameters are calculated and determined based on the design method of the pump and the formula of the guide vane and three sets of models for each parameter are also studied.According to the CFD numerical simulation,the influence of the structural parameters on the pump performance is also analyzed.(3)The two-stage centrifugal pump is taken as the calculation domain according to the flow characteristics of multistage centrifugal pump.The four geometric parameters are analyzed and compared according to the orthogonal test method and then the optimal value of each parameter is identified based on the test result.It is found that the head and efficiency of optimized computational domain compared to the original one have been significantly improved,with 5.78 m head increase and 4.22% efficiency increase.The influence of the number of blades on impeller and guide vane is analyzed,and the best matching method of the blade number in the two stage computing domain is finally determined.It is indicated by the results that the head and efficiency of the computational domain model after the optimization of the blade number are higher than that of the original calculation domain,with 7.92 m head increase and 6.01% efficiency increase.