Flow Field Analysis And Multi-objective Optimization Of Low Specific Speed Multistage Centrifugal Pump

Low specific speed multistage centrifugal pump is widely used in petrochemical,electric power,metallurgy and other fields.In the process of its operation,due to the influence of the working environment,there will often be deviation from the design working condition,restricted by the operation conditions of other units,the flow and head of multistage centrifugal pump will often work in the small flow area.As a result,the multistage centrifugal pump performance declines,energy consumption increases,unstable operation and other problems occur.To solve these problems,this paper mainly studies the internal flow field characteristics,multi-objective optimization and experiments of low specific speed multistage centrifugal pump.Specific work is as follows:(1)According to the structural characteristics and working principle of low specific speed multistage centrifugal pump,aiming at the problems in the working process of low specific speed multistage centrifugal pump,the numerical calculation method and optimization method are determined through comparative analysis.(2)Based on the prototype of a multi-stage centrifugal pump with low specific speed,a three-dimensional solid model and grid division independence verification were established.Through numerical simulation calculation,the internal pressure field and velocity field distribution of a multi-stage centrifugal pump with low specific speed were obtained under different working conditions.The numerical simulation results of the pump were compared with the experimental results,and the average relative error was less than 3.3%.Verify the feasibility and reliability of the numerical simulation method.(3)Through the analysis of the distribution law of the pressure field and velocity field of the prototype,the model was simulated based on the neural network,SPEA2multi-objective optimization algorithm was used for multi-objective optimization of the low specific speed multi-stage centrifugal pump,and NSGA-Ⅱ multi-objective optimization algorithm was applied to the control design,and the optimization variable group was screened to complete the optimization design.Under different working conditions,the numerical simulation of the optimized multi-stage centrifugal pump with low specific speed was carried out and the distribution law of pressure field and velocity field was obtained.The distribution law of the internal flow field of the pump was compared and analyzed before and after optimization.(4)According to the optimization results of the low specific speed multistage centrifugal pump,the mold opening experiment and test experiment were carried out and the experimental data of the performance characteristics of the optimized low specific speed multistage centrifugal pump were obtained.The experimental results show that the numerical simulation results are in good agreement with the experimental results.The optimal parameters obtained by SPEA2multi-objective optimization algorithm can significantly improve the hydraulic efficiency of multistage centrifugal pumps.In the test,the bearing temperature of multi-stage centrifugal pump with low specific speed remained basically constant,no mechanical seal leakage occurred and the displacement of pump shaft was good.Through comparison,it was found that the water efficiency of the low specific speed multistage centrifugal pump was increased by 3.65% compared with that before optimization.