Conservation of Energy Method for On-Road Aerodynamic Drag Investigation 2004-01-1148
A significant reduction of the aerodynamic drag can be achieved by the refinement of the vehicle underside. But the investigation of the aerodynamic effectiveness of underfloor panels in wind tunnels turns out to be a challenging task. For this reason on-road methods like coastdown analysis are frequently employed. Most of these advanced coastdown methods determine the coefficients of the total drag by fitting a mathematical model to the measured velocity data. This requires separate time consuming tests in the laboratory to measure the wheel and transmission losses.
The objective of the presented work was the development of an analysis method, which enables a simpler and more practicable on-road determination of aerodynamic improvements. In this method the rolling resistance can be factored out by employing the conservation of energy as basic approach for the investigation of air drag differences. The only required instrumentation is a dynamic air speed indicator and an intelligent memory device to enable a velocity-time and airspeed-time history. No separate test in the laboratory or time consuming preconditioning of the vehicle is necessary.
Citation: Bratschitsch, E., Bischof, G., Haas, A., and Kaltenhauser, A., "Conservation of Energy Method for On-Road Aerodynamic Drag Investigation," SAE Technical Paper 2004-01-1148, 2004, https://doi.org/10.4271/2004-01-1148. Download Citation
Author(s):
Emilia Bratschitsch, Günter Bischof, Anton Haas, Albert Kaltenhauser
Affiliated:
FH Joanneum, BMW Forschung und Technik GmbH
Pages: 9
Event:
SAE 2004 World Congress & Exhibition
ISSN:
0148-7191
e-ISSN:
2688-3627
Also in:
Vehicle Aerodynamics 2004-SP-1874
Related Topics:
Drag
Mathematical models
Aerodynamics
Energy conservation
Wind tunnel tests
Historical reference
Technical review
Transmissions
Fittings
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