Based On Fluent Electric Car Body Aerodynamic Shape Optimization Design Research

In recent years, with the development of economy in our country, the demand for automotives continues to grow. While facing the foreign-brand cars’competition, our national-brand cars should enhance their competitive power by raising the design level and promoting the development capacity, in which the vehicle body modeling is the key point of car design. In addition, along with the problem of environmental protection and the short of energy is getting more and more serious, electric cars are gradually become the direction of the development of the car industry because of their zero emissions and low noise advantages. Yet for now, they haven’t made any breakthrough in the field of battery, motor technology and controller technology which leads to the insufficient driving range to become the electric vehicles’bottleneck that greatly impede the development and popularization of electric vehicles. As the automobile aerodynamic characteristics have directly effects on traction ability, fuel cost, handing and stability, so the important way to extend battery service lifetime and increase driving range is to make a good design of the automobile aerodynamic characteristics. Faced with this situation, this thesis focus on the two parts:Body Styling Design and Body Outer Flow Field Numerical Simulation,In this paper, a preliminary aerodynamic design of an electric vehicle body was made according to the theories of vehicle aerodynamics and computational fluid dynamics, the aerodynamic characteristics of the model was analyzed by using the Fluent software, and optimized the local shape based on the results of the analysis, with view to provide some help on the aerodynamic shape of the electric vehicle body design.Firstly, in order to guarantee the operator’s field of vision and operation comfortableness, the author carried on the car body general arrangement and fixed the hard point position of the automobile body. According to automobile aerodynamic theory, reasonably definite the parameters to make a preliminary air operated modeling design to the electric automobile body, and according to the defined final outline, drawn the sketch of the car and constructed the three-dimensional digital model in the Alias software and applied the method of rapid prototyping to get the physical model.Secondly, simplified the accomplished digital model properly, determined the computational domain and meshed it. Imported the gird file into the Fluent software and carried out numerical simulations after setting up boundary conditions and related calculation parameters. Imported the simulation results into the TECPLOT software, exported the velocity vector of the external flow field, the pressure distribution and the 3-D flow line around the body. Analyzed the external flow field characteristics, gat the air dynamic characteristics by calculating the aerodynamic drag coefficient and the aerodynamic lift coefficient to verify the vehicle’s good aerodynamic performance, and analyzed some problems that still exist.Finally, made the partial of the original model improved according to the problems of its aerodynamic characteristics, carried out numerical simulations to the improved model, calculated the aerodynamic drag coefficient and the aerodynamic lift coefficient, contrasted and analyzed the result with the primary model, provided a basis for the aerodynamic design of the vehicle body from the aerodynamic point of view.