Research On Aerodynamic Characteristics Of SUV And Optim-ization Of Drag Reduction Based On Star-ccm+

With the rapid development of Chinese economy,the number of car ownership continues to increase,and energy conservation and emission reduction and oil price increase have become issues that China must face.A large part of the fuel consumption of the car during driving is used to overcome the air resistance.In terms of reducing fuel consumption,developing new energy vehicles and reducing vehicle resistance are the two main ways.Limited by the development of automotive power batteries,the development of new energy vehicles is not mature,so in the future for a long time,reducing vehicle resistance is still the main means to solve the above problems.According to the drag reduction method,the car drag reduction can be divided into shape drag reduction and additional device drag reduction.The drag reduction of the additional device plays an important role in improving the aerodynamic performance of the car.In this paper,SUV is taken as the research object.Firstly,it is modeled in the 3D graphics software CATIA,and then imported into the simulation software Star-ccm+ for mesh division and simulation calculation.Finally,the simulation results are post-processed to get the speed.Pressure and turbulent energy cloud map.According to various cloud diagrams,the following conclusions are drawn: in order to reduce the aerodynamic drag of the vehicle,it is necessary to reduce the differential pressure resistance before and after the vehicle body,and the main cause of the differential pressure resistance is that the tail end,the side end and the bottom end air flow are separated at the rear of the vehicle.The interaction forms an extremely complicated flow field and eddy current structure.The tail vortex is accompanied by the loss of energy,which increases the pressure difference resistance before and after the body,which is not conducive to reducing the driving resistance of the car.Through the simulation analysis of the original car,the main source of automobile resistance is obtained,which is used as the main basis for the additional devices of the car at the top,side and bottom.After determining the additional device model at different positions of the car,it is necessary to separately select the design variables for each additional device to establish an approximate model,and use the optimization algorithm to globally optimize the approximate model of each additional device.According to the research results,it is known that the installation of additional devices at the top,bottom and side ends of the rear end is beneficial to optimize the flow field at the rear end of the vehicle,reduce the pressure difference between the front and rear of the vehicle body,and reduce the aerodynamic drag of the vehicle.Finally,the optimized additional devices at the top,bottom and side ends of the rear end achieved 5.8%,4.3% and 3.8% drag reduction,respectively,which provided a reference value for the drag reduction optimization of the car.After obtaining the optimal device model of the tail end,side end and bottom end respectively,the drag reduction effect of different combination arrangement schemes is studied.According to the simulation results,the three are combined and installed at the rear of the vehicle body,which can be used for the original car.To the maximum drag reduction effect,the drag reduction rate is 9.2%.At the same time,the combination of additional devices does not simply add up the drag reduction effect of the car.Therefore,in the future engineering practice,it is necessary to pay attention to the reasonable structural design of the car attachment.