Experimental and numerical investigation on wheel regional aerodynamics in an electric vehicle

The aerodynamic development of electric vehicles (EVs) has drawn more and more attention recently due to its direct relationship with EVs’ power consumption and driving range. The wheel regional aerodynamics are complex and important, rendering them a hot research topic. In this work, wind tunnel tests and CFD simulations are performed to investigate the regional aerodynamics of wheels in an electric SUV, taking into account the interference effects between the tires, automatic grille shutter (AGS), and front wheel deflectors. Since the vehicle’s aerodynamic drag coefficient is the focus of this research, three parameters with major effects on the drag coefficient, including tire width, AGS status (open/closed) and height of front wheel deflectors, are chosen for a parametric study in a wind tunnel. The wind tunnel results show that the experimental drag coefficient increases linearly with the increase in tire width. Linear regressions show that the sensitivity coefficients, affected by the status of the AGS and height of the front wheel deflectors, range from 5.0 to 7.6 counts for a 10 mm increase in tire width. The drag coefficient is reduced by reducing the height of the front wheel deflectors from 50 to 30 mm in all cases investigated, and the reductions range from 0.8 to 7.6 counts. Reductions of the drag coefficient by closing the AGS range from 13.2 to 19.1 counts and a cooperative drag reduction effect is observed between closing the AGS and reducing the height of the front wheel deflectors. CFD simulations are performed to visualize the flow patterns, and the flow field information extracted is used to explain some of the experimental phenomena. This work proves that both wind tunnel tests and CFD simulations are useful tools for investigating wheel regional aerodynamics in electric vehicles.