Abstract
Aerodynamics has a strong influence on the design of a vehicle. Over half the fuel used by modern passenger is wasted in overcoming aerodynamic drag. Despite intense research into the flow around the upper part of the vehicle, the drag coefficient has plateaued at about 0.3 and further drag reductions will come from the under body including the wheels and associated areas. The wheels and wheel-housings are components which have had insufficient aerodynamic consideration although wheels contribute significant disturbance to the airflow around a vehicle.
In this work, CFD techniques were used for parametric study and analysis of wheel-housing geometry of a generic test vehicle. A relatively simple two wheeled body was developed to reproduce front and rear wheel effects of a typical four wheeled passenger car. Benchmarking experiments were performed in the RMIT Industrial Wind Tunnel (which does not have facilities to work with conventional rotating wheels) using a simple, cost effective double-symmetry experimental testing concept. Parametric tests revealed that aerodynamic forces on the front wheel housing is directly affected by the flow impinging onto the wheel and wheel housing whereas the rear wheel-housing is sensitive to the changes in wheel-housing geometry. A number of parameters were analyzed for their individual effects on aerodynamics of total vehicle. It was found that Cogotti’s (1983), findings to have a smaller wheel-housing to wheel volume ratio was only suitable for only rear wheel housing. The flow structures and resulting pressures and forces indicate that both front and rear wheel-housing shapes have a significant influence on the aerodynamics of the total vehicle and thus fuel economy and improved road safety.
Keywords: Vehicle, Aerodynamics, Wheel housing, Wheel well, Drag, Lift