Research On The Multi-condition Optimization Of An Automotive Electronic Water Pump

This study is supported by National Natural Science Foundation of China“Study on the Mechanism of Distortion Flow Induced Noise of Centrifugal Pump”(51509108),Jiangsu Province Natural Science Fund“Study on Low-noise Hydraulic Optimization Design and Key Technology of Centrifugal Pump”(BK20150516),and the support of the automotive electronic water pump horizontal commission project.This paper is also funded by the National key research and development project “Research and Application Demonstration of Key Technology for Complex Environmental Engineering Rescue”(2018YFC0810505).Under the background of energy conservation and emission reduction,the scale of the global new energy automobile industry continues to expand,and the development of new energy vehicles is one of China's national strategies.The cooling pump is the core component of the vehicle cooling system,and the conventional mechanical cooling pump is mainly driven by the engine,and its output is coupled with the engine speed,which can not meet the needs of industrial development under the new situation.With the announcement of the ban on the sale of fuel vehicles by many governments,the auto parts manufacturers have been developing automotive electronic water pump.The development of domestic automotive electronic water pumps started late,and the efficiency is far lower than the world's leading level.Under the basic national policy of energy conservation and emission reduction,the development of an efficient automotive electronic water pump model is one of the current research priorities.In this paper,theoretical analysis,numerical optimization and experimental verification are used to study the hydraulic optimization design of a certain automotive electronic water pump.The main research work and innovations are as follows:1.Through the analysis of the development history of the vehicle cooling system,it is considered that the automotive electronic water pump is the future development direction of the vehicle cooling pump.It is the current technical difficulty and focus to improve the efficiency of the multi-condition under high speed.The traditional pump design is mainly based on semi-empirical and semi-test,the design cycle is longer,and the auto parts industry is upgrading faster.It is urgent to introduce intelligent optimization methods and build an automatic optimization platform for the hydraulic development of automotive electronic water pump.2.Based on the design requirements of automotive electronic water pump,the model pump studied in this paper was designed.Based on the CFD method,the preliminary calculation of the flow field in the model pump was carried out,and the external performance test was carried out.The results show that the SST k-? turbulence model can be used to predict the performance of automotive electronic water pump.The simulation values of the head and the efficiency of the full flow are basically the same as the experimental values.The simulated head is larger than the experimental head.Under the design flow,the relative error between the simulated head and the test head is small,and the calculation accuracy basically meets the subsequent optimization requirements.3.This paper expounds the design of the speed coefficient method of automobile electronic water pump.The key parameters of four impellers are selected as the optimization variables by empirical analysis.The experimental scheme is arranged scientifically by orthogonal test design,and three flow points of 0.8Qd,1.0Qd and 1.25 Qd are selected as the assessment points,the mathematical model is constructed with the highest weighted average efficiency under three operating conditions as the objective function.All the schemes were calculated by the numerical simulation method consistent with the original scheme,and the target values of each scheme were obtained.The optimal scheme was obtained by range analysis and variance analysis.By comparing and analyzing the changes of external characteristics and internal flow changes before and after optimization,the relevant laws of the performance improvement of automotive electronic water pumps are mastered.The results show that the change of blade number has the most significant influence on the pump performance of the model and the order of the factors affecting the target is Z,D2,b2,?2.After optimization,the head of each point is improved,and the weighted average efficiency of the optimization scheme is increased by 3.29%.The efficiency improvement under small flow conditions is not obvious.The optimal operating point efficiency after optimization is increased by 3.66%.As the flow rate becomes larger,the efficiency of the optimization scheme is significantly improved,and the high efficiency zone is effectively broadened.4.Based on Isight software,an intelligent optimization platform for automotive electronic water pump was built.Integrate CFturbo,ICEM and CFX through softwareprovided program interfaces and Windows batch commands,combined with multi-island genetic algorithm to optimize the performance of automotive electronic water pump.The results show that the optimal efficiency of the automotive electronic water pump is improved by 2%,and the efficiency of the large flow condition is increased by 3.09%.The head of the design condition point is significantly improved compared with the previous one.The efficiency weighted average of the three working conditions is 55.24%,which is 2.02% higher than before optimization,and achieves the purpose of optimization.After optimization,the flow state in the impeller flow channel is relatively flat and the flow loss is smaller.The optimized pressure distribution is more uniform than before optimization,and the pressure from the hub to the rim is gradually increased,and the blade leading edge pressure is effectively reduced.5.On the basis of the numerical calculation of the original model pump flow field,aiming at improving the heat dissipation performance of the automotive electronic water pump motor,the rear pump chamber structure was redesigned and the external characteristics and internal flow field before and after optimization were compared.The results show that the head and efficiency are almost the same under the two schemes,and there is a certain deviation in the head only at small flow rates.After adding the hollow shaft return groove structure,a small part of the liquid in the volute smoothly enters the rear pump chamber and flows out from the return tank.It is integrated into the inlet flow of the impeller and forms a self-circulation,which can exert a strong cooling effect on the motor and greatly promote the reliable operation of the pump.