Simulation Analysis And Optimization Of Thermal Performance Of Engine Compartment Of A Car

The engine compartment is an integrated area of the main components of the car.The flow field characteristics in the cabin not only affect the internal flow resistance of the vehicle,but also have a great influence on the heat dissipation of the components inside the cabin.The heat dissipation characteristics in the cabin will directly affect the overall performance of the vehicle.Therefore,it is necessary to conduct accurate and in-depth research on the heat dissipation characteristics and flow field in the engine compartment.As the overall performance of the vehicle is greatly improved,the requirements for thermal management of the engine compartment are becoming more and more demanding.Therefore,there is still a lot of room for development and optimization of engine compartment thermal management technology.In this paper,a turbocharged real vehicle is taken as the research object,and the computational fluid dynamics method is used to simulate the flow field and temperature field in the cabin.Combined with the simulation results,the lower intake grille and the hood spoiler are multi-targeted.Optimize the design,simulate with different boundary loading methods and compare its advantages and disadvantages.The main research contents are as follows:(1)Using CFD software to study the flow field characteristics and temperature field characteristics in the engine compartment under the four conditions of idle speed,low speed climbing,high speed climbing and high speed,and obtain the surface temperature distribution of key components.(2)Comparing and analyzing the simulation results of the four working conditions,it is found that there is local high temperature in the cabin under high speed conditions.Combined with the characteristics of the flow field in the car,the flow state of the cooling airflow in the cabin is analyzed,and the cause of the local high temperature in the cabin is obtained and an optimization scheme is proposed.(3)According to the comparison of the flow field and the temperature field under the four working conditions,it is found that the front lower intake grille and the hood spoiler have a great influence on the heat dissipation characteristics in the cabin,and the appropriate variable optimization design is selected for the initial model size.Scope,using the co-simulation method to carry out multi-objective optimization under high-speedconditions,to obtain the best heat dissipation performance in the cabin and the largest air intake.(4)Based on the optimization scheme,two fan area models are combined with two thermal boundary conditions(solid fan and surface temperature,fan boundary and surface temperature,solid fan and equivalent heat dissipation,fan boundary and equivalent heat dissipation)The simulation calculation is carried out to analyze the distribution of the flow field and temperature field and the influence on the heat dissipation performance in the cabin.The following main conclusions were drawn from this study:(1)The intake air volume of the upper and lower grille is positively correlated with the vehicle speed,but the intake efficiency of the lower grille is higher than that of the upper grille;(2)For this model,when the angle of the lower grille and the angle of the hood spoiler are 16.6° and 21.6°,respectively,the air flow entering the grille and the hood reaches the maximum value,and the surface temperature of the lug reaches the minimum value of147.6 °C;(3)It is found through verification that when the thermal boundary loading method with equivalent heat dissipation is selected,the surface temperature distribution of each component is more in line with the real situation;(4)The load distribution method using the Fan boundary is more consistent with the temperature distribution of the components in the cabin than when a solid fan is used.Therefore,the Fan boundary can be used instead of the solid fan.In this paper,the influence of different boundary loading methods on the flow field and temperature field in the engine compartment under different driving conditions is studied,which provides a reference for the early development of the engine compartment.