| The cooling effect of the engine compartment affects the power and economy of the vehicle directly.Due to the complex gas flow state and internal thermal environment in the cabin,finding out whether there is a floating dead zone and a local high temperature zone in the cabin has an important impact on the service life of the cabin components and the normal operation of the cooling system.Thus affecting the vehicle’s dynamics and economy.Therefore,vehicle compartment thermal management has become one of the problems that must be solved in the process of China’s independent brand vehicle forward research and design.Traditional vehicle compartment heat dissipation performance assessments were usually based on engineering experience and repeated tests until the thermal performance meets the design requirements.This design method is highly dependent on engineering experience,and the test time is long,costly and subject to objective conditions.Now,numerical simulation is the main research tool in the cabin thermal management design because it could provide some cabin flow field and temperature parameters that cannot be obtained by experiments.In this paper,a SUV from South East(Fujian)Motor Corporation LTD is selected as the prototype,and the thermal management design of engine compartment is carried out with numerical simulation as the main part and experiment as the auxiliary part.Firstly,the three-dimensional simulation technology is used to simulate the flow field and temperature field of the vehicle prototype.Then,the 1D/3D co-simulation technique is used to simulate the performance of the cooling system.Finally,the engine room structure is improved according to the problems found,and the effectiveness of the improved scheme is verified by vehicle thermal balance test.The main research work is as follows.(1)According to the three-dimensional model of SUV,a three-dimensional engine compartment thermal management analysis model is established based on the finite volume method.The porous medium model is used to simulate the heat exchanger,and the MRF model is used to simulate the fan.The thermal management analysis of the whole vehicle model is carried out under two extreme conditions at low and medium speed climbing and high speed climbing.Through the comparative analysis of the whole vehicle flow field,engine cabin flow field and the temperature distribution of key parts under two working conditions,it is found that the temperature of the axle sleeve and engine control harness is high under low and medium speed climbing conditions.Furthermore,the reasons for the high temperature of the axle sleeve and engine control harness are analyzed,and a preliminary solution is proposed.(2)Based on the test data of heat exchanger,thermostat,fan and the arrangement of cooling system of the vehicle,a 1D simulation model of cooling system is established in one-dimensional software Flomaster.And AVS module is used to improve the accuracy.Combining the relevant data of 3D simulation analysis,the 1D/3D joint simulation analysis of the cooling system performance under the two working conditions of the vehicle was carried out.The simulation results show that the engine outlet water temperature is high under two working conditions.Combined with the 3D flow field map,it is found that the intake air volume of the cooling air is insufficient,and the initial improvement scheme is proposed.(3)Analyze the advantages and disadvantages of each solution based on the principles of cost control and ease of development.The best solution is to install the deflector and change the straight anti-collision beam to the U-shaped anti-collision beam.The numerical model with the best scheme is analyzed,and the simulation results verify the effectiveness of the improved scheme.(4)The vehicle thermal balance test was carried out at the sample car stage,to verify engine heat damage simulation accuracy more than 90%,cooling system simulation accuracy is over 95% and deviation is analyzed. |
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