In English

The Aerodynamic Influence of Rim Design on a Sports Car and its Interaction with the wing and Diffuser Flow

Johan Cederlund ; Jakob Vikström
Göteborg : Chalmers tekniska högskola, 2010. 91 s. Diploma work - Department of Applied Mechanics, Chalmers University of Technology, Göteborg, Sweden, ISSN 1652-8557, 2010.
[Examensarbete på avancerad nivå]

Global climate change and increasing fuel prices demand more efficient vehicles. Today the automotive industry invests significantly into developing more efficient engines and to reduce the required force to propel the vehicles. For a passenger car the aerodynamic drag is a dominant part of the total resistance at highway speeds. In the area of sportscars, aerodynamic drag is even more dominant due to higher speeds and the fact that aerodynamics is also used in order to increase downforce. This result in contradictory demands as downforce often comes with a drag penalty. There has to be a delicate balance between the two. Even though the fuel price is not an issue when racing, there is a demand for efficient vehicles in order to obtain as much performance as possible within the rules. The wheels have been shown to have a large influence on the global aerodynamic properties of a vehicle. It has also been shown that the local flow field around the wheels and wheel housings is highly dependent of the rim design. In this project the influence on the global as well as the local aerodynamic properties from the rim design was studied. In addition the interaction between rim design and diffuser was investigated as well as the interaction between the diffuser and the wing. The simulations showed clearly that a substantial decrease in drag can be achieved with proper rim design. Blocking the crossflow through the rims result in increased static pressure in the front wheel house and thereby an increase in lift, whereas blocking the crossflow in the rear result in increased downforce due to an increased flow rate through the diffuser. It was however shown that the resulting flow around the rear wheel was highly dependent of the rim design in the front. Furthermore it was shown that removing the lower wing increase the downforce generated from the upper wing whilst the base wake aft of the vehicle was substantially reduced and thus also the driving force for the diffuser leaving it less efficient.

Nyckelord: External Aerodynamics, Road Vehicle Aerodynamics, CFD, Wheel Modeling, Rim design, Drag Reduction, Downforce, Wing, Diffuser



Publikationen registrerades 2011-01-14. Den ändrades senast 2013-04-04

CPL ID: 133661

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