Study On Aerodynamic Performance Of Centrifugal Compressor Blades Based On Multiple Objectives

Centrifugal compressors are widely used in turbocharging and other technical fields because of their advantages such as compact structure,stable operation,high single-stage pressure ratio and simple manufacturing process.As the low-pressure compressor of direct series two-stage turbocharging system works under complex conditions of variable speed,the internal flow is complicated.How to realize the high efficiency and high-pressure ratio operation of compressor has always been a hot spot in impeller optimization design.Considering the machining cost and the available centrifugal impeller styles on the market,the traditional centrifugal compressor manifold blade tends to follow the main blade parameters without separate design,so to further improve the performance of the centrifugal compressor,the study of the internal flow field of the compressor impeller and the optimized modification of the main blade and manifold blade is particularly important.This paper takes the low-pressure stage compressor of a two-stage turbocharger system used in a heavy-duty diesel engine as the research object,and adopts the numerical simulation method to numerically solve its internal flow field,and analyzes the internal flow field characteristics of the centrifugal impeller more specifically and deeply,mainly focusing on the main blade,the key inlet and outlet parameters of the splitting blade,as well as the influence of the change of the position and length of the splitting blade on the performance of the centrifugal compressor to make corresponding conclusions.The main contents of this paper include:1.Based on the existing basic research,the characteristics of different two-stage pressurization methods are compared in detail,and the pressurization mechanism and main structure of the turbocharger system and centrifugal compressor are highlighted.2.The CFD numerical calculation model of centrifugal impeller is established for the research object of this paper.Based on the characteristics of periodic mesh of rotating machinery,the single flow channel model is taken as the research object and meshed;the boundary conditions are set and solved numerically by Fine/Turbo software;the reliability of the adopted numerical simulation calculation method is checked by comparing and analyzing the experimental data and numerical simulation results.3.The effects of main blade inlet airflow tip angle,main blade outlet airflow backward bend angle,diverter blade inlet airflow tip angle,diverter blade circumferential position and length on the internal flow characteristics and aerodynamic performance of the centrifugal compressor were investigated;through the optimization method combining Latin hypercube experimental design,Kriging agent model and NSGA-Ⅱ multi-objective genetic algorithm,the multi-objective optimization search was completed and the Finally,the accuracy of the multi-objective optimization method was verified by numerical simulations,and the pressure ratio and isentropic efficiency of the optimized individual were improved by 3.1%and 2.7%,respectively,compared with the original design solution.4.The one-dimensional performance simulation model of the engine with two-stage turbocharging system is established by GT-Power software,and the validity of the numerical simulation model is verified by bench test;under the condition that the main technical parameters of the engine are not changed,the influence of the optimized low-pressure stage centrifugal compressor on the external characteristic performance of the engine is compared and analyzed.