Coupe and Analysis of External Flow Field

With the development of automotive technology, and improve road traffic, vehicle speed greatly improve the utility, vehicle aerodynamics in the automotive industry one of the key research directions. Aerodynamics of wind tunnel test is the traditional method, this method of testing facilities require a higher and longer study period. With the development of computer technology, computational fluid dynamics (CFD) research in the automotive application of aerodynamics is becoming more important, CFD method has a short cycle, low cost, no car model so real with this method of guidance design, both in terms of vehicle development or improvement, have played to improve product quality, and enhance the role of self-development capacity. Coupe is a car-based features, adding sports car in which elements of both a car manned and practical functions, but also has the sporty styling. Here, we use a coupe CFD method for numerical modeling of three-dimensional flow field, combined with aerodynamic theory of their aerodynamic shape and performance analysis and optimization. Topics from the coupe of the reverse design of a project. The project is the use of CATIA 1:1 draw three-dimensional model of the real vehicle. In the process of establishing simulation model, taking into account the simulation time and computer hardware problems, some details on the real vehicle accordingly simplified. ICEM software and then use the finite element model. In this paper, thirteen prism tetrahedral mesh grid hybrid solution, using the density surrounding the coupe body to its surrounding grid computing encrypted area, and the coupe to do locally refined mesh surface plane. Realizablek-ε turbulence model used, and in their use of standard wall function near the wall to improve the accuracy of the body surface flow simulation. Combined with first-order upwind and second-order upwind characteristics of each of two discrete scheme in the calculation process, the first order upwind first iteration after a certain number of second-order upwind scheme to improve the calculation accuracy and convergence, reduce the computing time.Finally, the model using FLUENT analysis, the body surface pressure distribution and velocity vectors, by analyzing the vehicle velocity and pressure characteristics of the surface to understand the movement of air and circumstances. And the results calculated by simulation of the coupe's aerodynamic drag coefficient and lift coefficient.Aerodynamics combined with theoretical analysis and the actual shape of the coupe, the local optimization, the results were compared before and after optimization and analysis, to reduce aerodynamic drag and aerodynamic lift and improve vehicle handling and stability and economic purposes, this sedan improvement of sports car styling reference. According to this simulation results combined with coupe styling can be seen, for the coupe, the streamlined shape features, the aerodynamic drag coefficient is relatively small, but the aerodynamic lift coefficient instability. For such a high-speed coupe car, for security and stability considerations, reducing its aerodynamic lift aerodynamic drag than the decrease has more practical significance.The results show that the additional aerodynamic coupe rear wing on aerodynamic lift devices such as have good regulation. The chassis structure of the simpler, the better the vehicle's aerodynamic performance. For such a high-speed coupe car, or even the bottom of the body surface can be used to generate negative lift. 

 

Keywords: computational fluid dynamics simulation optimization of aerodynamic drag aerodynamic lift