Browse Publications Technical Papers 2018-37-0014
2018-05-30

Numerical analysis of aerodynamic impact on passenger vehicles during cornering 2018-37-0014

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 step towards accomplishing this, is to reduce fuel consumption by improving the aerodynamics and minimizing the drag of vehicles. 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. Physical tests have been conducted in the past by placing, for instance, a car sideways in a wind tunnel or by using a curved test section. However, these attempts were far from being able to reproduce the same flow condition as in actual cornering situations. In this study, the effects of cornering on the drag force are investigated numerically using a generic vehicle model called the DrivAer. The model is considered in two different configurations: the notchback and the square back. 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 as a 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 underbody of the 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 square back and the notchback similarly, although the square back experiences consistently a slightly higher drag.

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