Multi-objective Optimization Design Of Low Specific Speed Centrifugal Pump Blades Based On CFD Analysis

Low specific speed centrifugal pumps generally have poor comprehensive hydraulic performance,and the impellers is core components which determine the external characteristics of pumps.In order to improve its hydraulic performanc,this paper first uses the latest NSGA-III intelligent algorithm combined with approximate models,numerical simulations and other methods to optimize the impellers.According to the experimental data,the optimization results were re-optimized,and a better comprehensive performance was obtained.First,based on the hydraulic loss model and sensitivity analysis results,the impeller exit width,blade exit diameter,and blade exit placement angle were selected as design variables.An approximate model between the design variables and the external characteristics of the pump was established through the BP neural network.Finally,the NSGA-III algorithm was used for multi-objective optimization,and the first optimization was completed.Based on the first optimization,relying on the manufacturing platform and the national pump test center of the enterprise,casting and the experiment of external characteristics was carried out.According to the results,pros and cons of the first optimization are summarized.By comparing the numerical simulation with the experiment results,the problems in numerical calculation are found,and preparations are made for the second optimization.Considering the accuracy and stability of the solution,the numerical calculation method was modified during the second optimization.On this basis,the reconstruction of the sample database,the reconstruction of the approximate model,and the second optimization by NSGA-III algorithm are completed.In addition,the remaining important structural parameters of the impeller are optimized.By adjusting the base circle of the volute and the cutting impeller,the efficiency curve was corrected and the overall performance was improved.According to the CFD calculation results,the final head is 51.34m,efficiency is 66.16%,shaft power is 21.14k W,and NPSH_r is 1.3168m.The occurrence of the head hump is avoided,and the distribution of the high-efficiency zone is more reasonable,which has reached the national secondary standard.