Design And Research On The Performance Of Automobile Electronic Water Pump Based On CFD

As petroleum resources become increasingly scarce,new energy vehicles have received extensive attention.To ensure the long-term,efficient,stable,and safe operation of lithium-ion battery packs,it is necessary to ensure the normal operation of their cooling circulation systems.As the power source of the cooling circulation system,the automotive electronic water pump has been widely used in new energy vehicles.However,both the design method and performance of the automotive electronic water pump face urgent need of improvement.Therefore,designing a more efficient and stable electronic water pump is of significance for research and development of new energy vehicles featured by environmental protection,energy conservation,safety,and comfort.This presented thesis focuses on the electronic water pump of a certain vehicle’s thermal management system.The combination of computational fluid dynamics(CFD)and experiments is employed to assist in the optimization of the electronic water pump.A numerical simulation model is established.The performance of the prototype is tested.A comparison between the test result and the numerical data is conducted,and the accuracy of the numerical simulation method is verified,providing a data support of research method for the optimization of the hydraulic components of the electronic water pump.Combining numerical results and conventional design principles,the structure of the electronic water pump is optimized.The test of the newly designed pump is conducted,and the results show that the expected goal has been accomplished.Moreover,the important role assumed by numerical simulation in terms of assisting the optimization design is demonstrated.Main contents and conclusions of the thesis are as follows:(1)A single pump test bench and a complete pump test bench are designed and constructed.The performance characteristics of the prototype pump are tested on both test benches.By comparing the performance curves of the single pump and complete pump,it is concluded that at the rated operating condition,the change of the head of the complete pump is negligible compared to the single pump.However,the efficiency of the complete pump decreases by 13.9% and the power increases by16.3%.This indicates that the system in which the pump is installed has a significant effect on the efficiency and power of the pump.Both the single pump and complete pump tests show that the performance of the prototype pump cannot satisfy the design requirements.Therefore,the hydraulic components of the pump must be optimized.(2)The numerical simulation model of the electronic water pump is established using commercial CFD software STAR-CCM+.By comparing the numerical simulation results with test data,it is observed that the difference of head,efficiency,and power is all lower than 5% corresponding to the flow rate range of 100–800L/min.This verifies the accuracy of the numerical simulation method.The reasons for the difference are analyzed.The feasibility of using CFD methods for the optimization of the electronic water pump is demonstrated.(3)The flow characteristics of the electronic water pump prototype are analyzed.The results indicate that there is typically a negative pressure region at the inlet of the blade back surfaces,which is particularly remarkable at low flow rates.As the flow rate increases,the range of negative pressure gradually is narrowed and shifts towards the center of the blades.The streamline distribution inside the impeller is uniform,and the flow is smooth and immune from complex flow phenomena such as secondary flow and vortices.As the flow rate increases,the distribution of the turbulence kinetic energy near the impeller becomes more apparent,while the turbulence kinetic energy near the volute wall attenuates.(4)The conventional centrifugal pump design theory is analyzed.Based on the design requirements and characteristics of the electronic water pump,relevant structural parameters are determined for the electronic water pump,and an optimization plan is formulated.Computational fluid dynamics methods are used to investigate the influence of the factors such as blade number,blade profile,and inlet edge on the performance of the electronic water pump.An optimized hydraulic model for the electronic water pump is obtained thereby.The analysis of the numerical results of the optimized hydraulic model indicates that the increase in the number of blades promotes the working ability of the impeller,thereby increasing the head and efficiency of the pump.However,increasing the number of blades also causes an increase in velocity fluctuations in the impeller.Adjusting the blade profile and inlet edge leads to the increase of the blade wrap angle,and thus the increase in the pump head and efficiency.(6)The optimized model of the electronic water pump is manufactured,and performance tests are conducted based on both the single pump test bench and the complete pump test bench.Through the single pump test,it is observed that at rated operating condition,the head of the single pump is 21.37 m and the efficiency is70.91%,satisfying the design requirement of a single pump with a head greater than21 m and an efficiency higher than 68%.In the complete pump test,it is concluded that at rated operating condition,the head of the complete pump is 21.31 m and the efficiency is 58.15%,meeting the design requirement of a complete pump with a head greater than 21 m and an efficiency higher than 58%.Through comparing the result of the single pump test and numerical result,the accuracy of the numerical method is further verified.