The effect of camber and yaw angle on the aerodynamic performance of rotating wheels in contact with the ground

Within the automotive industry, there has been a strong push to develop more fuel efficient vehicles and the aerodynamic drag is a key parameter which significantly affects this. The airflow around wheels can contribute to up to 30% of aerodynamic drag, and therefore understanding the flow structures associated with them is expected to provide significant opportunities to make vehicles more fuel efficient. Previous studies in this field typically only considered a straight upright wheel despite most vehicles utilising some camber and steer. This study quantifies the effect of camber and yaw on the aerodynamic performance of rotating wheels while in contact with the ground. The results indicate that when camber is increased, the aerodynamic lift and drag both decreased, while introducing yaw angle increased both. For the range of camber angles considered, a maximum difference in lift and drag of 44% and 14% was observed compared to 17% and 33% respectively for yaw. The contact patch shapes for the cambered and yawed wheels were observed to be the key reason for the differences. It was concluded that the aerodynamic forces are more sensitive to camber in comparison to yaw and that the contact patch is the most critical geometric feature as the changes to the flow all stemmed from the variations observed at this location.