Analysis of innovative aerodynamic devices on production vehicles

Yaw angles in a car's real environment are for 80% of the time different from zero. The reduction of car emissions is one of the significant challenges among automotive companies, including the PSA Group. Hence, the interest in studying solutions that can adapt to the environment around the vehicle increases. Our work shows the interest in having mobile aerodynamic devices concerning the vehicle's speed/yaw condition. We observe a drag reduction of around 1%, which is remarkable on a vehicle's scale. Besides, we would also like to build a database to prepare a doctoral thesis, in which, eventually, we will be able to implement the identified solutions on a production vehicle. We designed CAD parts and we tested them in a wind tunnel on a reduced scale during this study, more precisely on ¼, at the GIE-S2A in Montigny-le-Bretonneux. The interest of having mobile aerodynamic devices on the rear window of the vehicle is proven, which brings a significant improvement of the pressure field at the base and improves the associated drag. Post-processing of the data shows promising results. The vehicle's drag is significantly improved, while its lift has only a slight degradation. We observe negligible differences in the yawing moment of the car. Configurations with symmetrical flaps are not necessarily always beneficial. We identified configurations with two asymmetrical flaps that have better performances.