Passenger car fuel consumption is a constant concern for automotive companies and the contribution to fuel consumption from aerodynamics is well known. Several studies have been published on the aerodynamics of wheels. One area of wheel aerodynamics discussed in some of these earlier works is the so-called ventilation resistance.
This study investigates ventilation resistance on a number of 17 inch rims, in the Volvo Cars Aerodynamic Wind Tunnel. The ventilation resistance was measured using a custom-built suspension with a tractive force measurement system installed in the Wheel Drive Units (WDUs). The study aims at identifying wheel design factors that have significant effect on the ventilation resistance for the investigated wheel size.
The results show that it was possible to measure similar power requirements to rotate the wheels as was found in previous works. The magnitude of the measured ventilation resistance confirms the conclusion that this effect should be taken into account when designing a wheel.
It was found that some of the rim design factors have greater influences on the ventilation resistance than others. It was also shown that one of the investigated rims had lower ventilation resistance than measured for the fully-covered wheel configuration.
