This content is not included in your SAE MOBILUS subscription, or you are not logged in.
The Process of Making an Aerodynamically Efficient Car Body for the SAE Supermileage Competition
ISSN: 0148-7191, e-ISSN: 2688-3627
Published April 16, 2012 by SAE International in United States
Annotation ability available
In the summer of 2010, a new body shell for the SAE Supermileage car of Laval University was designed. The complete shell design process included, amongst other steps, the generation of a shape through the parametric shape modeling software Unigraphics NX7 and the evaluation of aerodynamic forces acting on the chassis using the open source Computational Fluid Dynamics (CFD) software OpenFOAM. The CFD analyses were ran at steady-state using a k-omega-SST turbulence model and roughly 2.5 million cells.
An efficient method for evaluating the effect of ambient wind conditions and vehicle trajectory on the track was developed. It considers the proportion of time that the car operates at each combination of velocity and wind yaw angle and computes the overall energy demand of the shell. An iterative process was conducted over a significant number of different shapes, which were generated by joining formula-based guide curves using intersection and tangency conditions.
The new shell has a 25 % larger frontal area due to modified design constraints. When aerodynamically compared to the smaller and already highly efficient old vehicle, reductions of 50 % of the negative lift, 15 % of the energy demand when driving forward, and 5 % of the energy demand when turning are achieved by the new design. Also, the drag coefficient is reduced by 20 %. These improvements come from the quasi-NACA profiles on the side and top walls; a reduction of cavities to prevent redundant frontal areas; a short vehicle and smother wheel cover closures; and a thorough study of the nose and tail. This paper describes numerical flow simulations and the changes that were brought to the vehicle body to make it as aerodynamically efficient as possible.
|Technical Paper||Rapid Design of a SUV by Combining Wind Tunnel Development and CFD Simulations|
|Special Publication||Thermal Systems Management and Heat Exchangers|
|Technical Paper||The Appropriate Use of CFD in the Automotive Design Process|
CitationGagnon, L., Richard, M., Beardsell, G., and Boudreau, M., "The Process of Making an Aerodynamically Efficient Car Body for the SAE Supermileage Competition," SAE Technical Paper 2012-01-0176, 2012, https://doi.org/10.4271/2012-01-0176.
- SAE 2012 SAE Supermileage rules SAE International Warrendale, PA 2011
- Maji, S. Almadi, H. “Optimization of the Aerodynamic Design of Supermileage Vehicle,” SAE Technical Paper 2007-01-0901 2007 10.4271/2007-01-0901
- Gagnon, L. Richard, M. Parallel CFD of a prototype car with OpenFOAM 5th OpenFOAM Workshop 2010
- Geuzaine, C. Remacle, J.-F. Gmsh : a three-dimensional finite element mesh generator with built-in pre- and post-processing facilities Int. J. Numer. Meth. Engng 79 11 1309 1331 2009
- Menter, F. R. Esch, T. Elements of industrial heat transfer predictions Proceedings of the 16th Brazilian congress of mechanical engineering 2001
- Santin, J.-J. et al. The world's most fuel efficient vehicle ETH Zurich 2007
- Ahmed, S. Ramm, G. Faltin, G. “Some Salient Features of the Time Averaged Ground Vehicle Wake,” SAE Technical Paper 840300 1984 10.4271/840300
- Lienhart, H. Becker, S. “Flow and Turbulence Structures in the Wake of a Simplified Car Model,” SAE Technical Paper, 2003-01-0656 2003 10.4271/2003-01-0656
- Franck, G. Nigro, N. Storti, M. D'Elia, J. Numerical simulation of the Ahmed vehicle model near-wake Technical report Instituto de Desarrollo Tecnologico para la Industria Quimica Argentina 2007
- Möller, S. Suzzi, D. Meile, W. Investigation of the flow around the Ahmed body using RANS and URANS with various turbulence models 3rd OpenFOAM Workshop 2008
- Hemida, H. Krajnovic, S. DES of the flow around a realistic bus model subjected to a side wind with 30° yaw angle The fifth IASME/WSEAS International Conference on Fluid Mechanics and Aerodynamics 2007
- OpenCFD OpenFOAM-1.6.× source code OpenCFD Limited Berkshire, UK 2009