Research On Optimization Of Car Body Modeling And Windage Characteristics

With the aggravation of the energy crisis and rising of oil prices,the economics of car driving has become an important factor for people to buy cars,while the wind resistance of a car is a key in dex that affects driving energy consumption,and its size is closely related to the car’s styling parameters.Therefore,in the automobile styling design,how to modify the automobile styling to improve the windage characteristics has become an important topic in the automobile styling design research.Based on the Computational Fluid Dynamics(CFD)theory,this paper proposes a method to improve the wind resistance performance of cars by modifying the styling parameters during the car’s design process.The main research contents of the paper are as follows:(1)A general parameterized model for body modeling of 3-compartment cars was established by using Grasshopper.The modification of car body modeling was realized by changing the relevant parameters,which provided an effective means for the modeling of different car models in CFD simulation.(2)The parameterized design of the car’s shape and surface were studied based on the NURBS surface theory.Different car models were obtained by modifying the curvatures of the transition surfaces,and a parameterized method was formed for modeling style adjustment by surfaces splicing.(3)Using Gambit for pre-processing of the model and Fluent for numerical simulation,the aerodynamic characteristics of the external flow field of the car body were numerical simulated.the aerodynamic characteristics of the car model were an alyzed respectively according to the pressure cloud diagram and the speed vector diagram of the car body surface,which provided a basis for the selection of styling parameters aimed at the optimization of aerodynamic performance.(4)According to the numerical simulation,three key styling parameters affecting automobile wind resistance were selected,and a scheme of Orthogonal Test with 3 factors and 3 levels was designed.27 models with different styling parameters were generated from the general parameterized model and CFD numerical simulation were carried out respectively.Aimed at the wind resistance coefficient optimization,a satisfactory car body model was obtained Orthogonal Test method.The numerical simulation result showed a significant reduction in wind resistance coefficient of the optimized model,which verifies the effectiveness of the design method.The research shows that the method proposed in this paper is feasible to improve the wind resistance performance by changing the shape parameters.The optimization of the body shape parameters during design process can effectively improve the wind resistance coefficient of the car.