Numerical Analysis of Aerodynamic Impact on Passenger Vehicles during Cornering
Artikel i vetenskaplig tidskrift, 2018
Governmental regulations and increased consumer awareness of the negative effects of green-house gases has led the automotive industry to massive invest in the energy efficiency of its fleet. One way towards accomplishing reduced fuel consumption is minimizing the drag of vehicles by improving its aerodynamics. Fuel consumption is measured by standardized driving cycles which do not consider aerodynamic losses during cornering. It is uncertain whether cornering has a significant impact on the drag, and the present study intends to investigate this numerically, using a generic vehicle model called the DrivAer. The model is considered in two different configurations: the notchback and the squareback. Cornering in various radiuses is modelled using a Moving Reference Frame approach which provides the correct flow conditions when simulating a stationary vehicle where the wind and ground are moving instead. Simulations are also performed for straight ahead driving conditions to provide data for comparison to a cornering vehicle. Results indicate that the drag increases when the cornering radius is small. This implies a higher fuel consumption than the standardized driving cycles suggest using straight-ahead drag coefficients. The detailed underbody of the DrivAer model is not symmetrical which, for large turning radiuses, results in a decrease of drag for left turns, while turning right results in an increase of drag. Cornering affects the squareback and the notchback similarly, although the squareback experiences a slightly higher drag throughout the cases investigated.