Browse Publications Technical Papers 2011-36-0079
2011-10-04

Methods of Drag Reducing without Losing Aerodynamic Stability Applied on SAE Reference Model 2011-36-0079

In last years environmental complains and instable petroleum prices have brought up a necessity to develop more efficient vehicles, witch shows less fuel consumption. With this aim better projected engines are being put into market utilizing renewable fuels like brazilian ethanol. Another fundamental way to improve efficiency is minimizing the resistance furnished by the vehicle to air flowing through during a translation.
This resistance reduction known as Drag is one of the main objectives of Vehicle Aerodynamic science. A low drag vehicle might be considered as more susceptible to air flow instabilities, as wind gusts, resulting in unsafe situations to its occupants therefore this material intends to demonstrate the vehicle drag and aerodynamic stability are distinct concepts and it is possible have a drag efficient car without losing drivability.
The use of Basic Models geometry to demonstrate aerodynamic concept is a feature defunded in automotive industry. Due to its advantages like simplicity and well correspondence to hatchback production cars geometry in this research it was opted to utilize a relatively newer model proposed by Society of Automotive Engineers (SAE).
The SAE model was simulated in a Computational Fluid Dynamics (CFD) ambient utilizing the commercial available package ANSYS Fluent 12.1v. The control volume was splinted in a mesh containing approximately 2.2 million cells and simulated according RANS method. In the first part the rear convergent angle was increased resulting on a drag reduction. The adoption of a diffusion angle in the vehicle underfloor was sufficient to guarantee the model's stability. The last part of research was evaluated the impact of pitch and yaw angles to the aerodynamics coefficients.

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