Analysis On Aerodynamic Characteristics Of The Rear Of Variant Vehicle

With the development of auto industry technology and improvement of living standards, people are more concerned about the safety of vehicles. At the same time, the utility and functional diversification of vehicles also meets a higher requirement. Currently, riding comfort and interior space maximization has become the focus of manufacturers. Vehicle variant technology based on customer requirement of daily convenience and practicability is gradually recognized by the public. For this reason, based on the theory of aerodynamics, through the variant design of the trunk, the complex relationship between the shapes of vehicle rear and the aerodynamic performance will be studied in this thesis, thereby providing theoretical and experimental data support for practical variable volume vehicle.In this thesis, based on CFD numerical simulation method, variant shape of the vehicle trunk and vehicle aerodynamic performance is particularly analyzed. On this basis, the link between the important parameters involved in the variant process and vehicle aerodynamic performance would be further fully analyzed. The main work is given as follows:1. Establishing 3D model of the vehicle. Using the collected points cloud data of car body, a 3D vehicle model in NX Imageware is created, which reflects the actual vehicle styling details as far as possible, laying the foundation for further research.2. Aerodynamic numerical simulation of sedan. Study vehicle flow field characteristics using CFD numerical simulation method, analyzing overall and local aerodynamic characteristics of sedan respectively from the aerodynamic force, body surface pressure distribution, velocity vector distribution, vehicle tail vortex and other aspects. The results provide a basis for the selection of optimal parameters of the vehicle rear design from the perspective of simulation.3. Determining key parameters of the variable volume vehicle rear optimization analysis. By the analysis of the aerodynamic performance of the vehicle before variation, especially for the rear, using simulation experiments and theoretical analysis method to determine the key parameters of the optimization analysis, the direction for the optimization analysis is pointed out. In which the optimization parameters are valid rear inclination angle, rear window inclination angle and trunk inclination angle.4. Optimization analysis of the variable volume vehicle rear. Firstly, carry out a single parameter simulation of variant vehicle to determine the reasonable range of each parameter. Secondly, using the orthogonal experiment method, synthetically study the influence of various parameters on CD value. In which the hatchback orthogonal experiment can be seen as a special single factor orthogonal experiment. Finally, determine the optimal parameters through orthogonal experiments and complete modeling and simulation. The results show that valid rear inclination angle has the maximal impact on CD value; the aerodynamic performance of the optimized vehicle has been clearly improved, and the optimization model is reasonable.Studies have shown that the method of using aerodynamic numerical simulation to optimize the vehicle design is feasible and after the optimization aerodynamic performance of the vehicle is obviously improved. The research in this thesis can be taken as the first step for the optimization design of variant vehicle, which lays the foundation for further research.