Experimental and numerical investigation on the influence of different detailed and deformed tires on the aerodynamics of electric vehicles

Abstract

To increase the driving range of electric vehicles, the reduction of aerodynamic drag plays an extremely important role. The wheels contribute more than a quarter of the overall aerodynamic drag for electric cars with relatively smooth underbody. As an essential component of the wheel, the aerodynamic performance of tires has also received extensive attention in recent years. This study investigated the influence of four different production tires combined with two rim designs on the vehicle’s aerodynamic performance based on an electric SUV. The wind tunnel tests were conducted to evaluate the aerodynamic forces, and the flow field changes around the tires were measured using a 14-hole pressure probe. Then, the dynamic deformation of the tires was captured to reproduce the actual tire geometry for simulation. The reasons for the drag differences caused by varying tires were thoroughly analyzed by comparing simulation and experimental results. The results show that the difference in drag coefficient between tires reaches up to 0.015, and the enlarged upstream separation induced by the front tires also alters the rear wake structure, significantly reducing base pressure. The effect of tire sidewall labeling and separation edge on drag was isolated by simulation, where the labeling protruding from the sidewall raises the drag coefficient by 0.004, accompanied by more vortices, while the separation edge increases the drag by up to 0.005 depending on its strength and number. It was also found that the dynamic deformation expands the size difference between tires, further increasing the drag differences.