Search Results

Being a continuous subject of research, the authors present in this paper new aspects and results concerning the relevance of diffusers in vehicle aerodynamics. In the first stage of investigation, a generic car model with wheels was considered, starting from the Ahmed body, and the effect of adding wheels to the body was studied. Latter, the influence of diffuser length and angle, within ranges relevant to hatchback passenger cars, on drag and lift was studied for the Ahmed body with wheels. The results show that the addition of wheels and wheelhouses results in increasing of drag and lift due to the vortices which originate from the wheels. Concerning the underbody diffuser, the results show that both drag and lift of the bluff bodies with wheels are reduced with increasing diffuser length for moderate values of angle, up to six degrees for the cases studied.

Using a prototype of terrain car as example, a process of flow simulation around a vehicle with rotating wheels is described by using a professional CFD (Computational Fluid Dynamics) software. The influence of the wheels motion on main aerodynamic characteristic of the car, drag, is studied in two ways, commonly used in wind tunnels [10], respectively with the moving wall approach and with the aid of the rollers for the wheels rotation. The conclusions are demonstrated by the results using the relative drag increment and by the computergraphics visualizations. There are also presented some considerations concerning the importance of the rotating wheels in aerodynamics of the road vehicle and the opportunity to simulate it in a virtual environment. The present contribution is a companion paper by Huminic & Chiru (2004).