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Parametric Study of Asymmetric Side Tapering in Constant Cross Wind Conditions
ISSN: 1946-3995, e-ISSN: 1946-4002
Published June 28, 2018 by SAE International in United States
Citation: Varney, M., Passmore, M., and Gaylard, A., "Parametric Study of Asymmetric Side Tapering in Constant Cross Wind Conditions," SAE Int. J. Passeng. Cars - Mech. Syst. 11(3):213-224, 2018, https://doi.org/10.4271/06-11-03-0018.
Sports Utility Vehicles (SUVs) often have blunt rear end geometries for design and practicality, which is not typically aerodynamic. Drag can be reduced with a number of passive and active methods, which are generally prioritised at zero yaw, which is not entirely representative of the “on road” environment. As such, to combine a visually square geometry (at rest) with optimal drag reductions at non-zero yaw, an adaptive system that applies vertical side edge tapers independently is tested statically.
A parametric study has been undertaken in Loughborough University’s Large Wind Tunnel with the ¼ scale Windsor Model. The aerodynamic effect of implementing asymmetric side tapering has been assessed for a range of yaw angles (0°, ±2.5°, ±5° and ±10°) on the force and moment coefficients. This adaptive system reduced drag at every non-zero yaw angle tested, from the simplest geometry (full body taper without wheels) to the most complex geometry (upper body taper with wheels) with varying levels of success; providing additional drag reductions from 3% to 125%. The system also shows potential to beneficially modify the cross wind stability of the geometry.