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Investigation of Tyre Geometry Influence on Road Vehicle Aerodynamics

Teddy Hobeika
Göteborg : Chalmers tekniska högskola, 2012. Diploma work - Department of Applied Mechanics, Chalmers University of Technology, Göteborg, Sweden, ISSN 1652-8557; 2012:47, 2012.
[Examensarbete på avancerad nivå]

Wheels aerodynamics and its e ect on vehicle aerodynamics have been the focus of several papers in the automotive industry. This report focuses mainly on the e ects of tyre geometry on road vehicle aerodynamics using Computational Fluid Dynamics (CFD) simulations. The tyres, obtained from the manufacturer as geometry les, were deformed based on measured wind tunnel data of the same tyres under similar load and rotating at 100 kph. The tyre deformation preserved a certain contact patch which was measured at stationary position. The main tyre comparisons included comparison of tyre pro les, di erent tyre patterns, and di erent combinations of pattern features of the same tyre. Some con gurations where evaluated with di erent rims to investigate the rim dependency of the results. As the simulations used Moving Reference Frame (MRF) approach then some con gurations were also evaluated with the same rim having two di erent spoke positions. The di erent pattern features investigated were: Main grooves, side grooves, and edge pattern. The main grooves gave the most consistent results of a few drag counts reduction in drag and lift. The di erent tyre pro les also showed di erent magnitudes of drag and lift reduction. The side groove showed an increase in drag in all open rim cases but with the magnitude dependent on the rim. The edge pattern however showed no clear trend although when di erent combinations of the above features were performed a strong interaction could be seen between the side grooves and the edge pattern. The presence of both showed a consistent increase in drag and lift with the magnitude of the increase being rim dependent. This increase in drag can be clearly seen in the ow eld as strong vortices generated at the front wheels due to both the edge pattern and the side grooves. Simulations also showed that the edge pattern had a bigger increase in drag on a sports wagon than on a sedan as having the edge pattern on the rear wheels have shown a drop in base pressure due to the interaction of the tyre vortices with the rear wake. The comparison of two di erent tyres showed a reduction in drag dependent on the spoke position. It is worth noting that the main di erence between Tyres 1 and 2 is the absence of the side groove on Tyre 2 as they both have a very similar tyre pro le. The reduction in drag between Tyre 1 and 2 has been replicated in the wind tunnel on one of the rims.

Nyckelord: CFD, Tire, Road Vehicle Aerodynamics, Volvocars, VCC, Tyre Deformation, Tyre Geometry, Tyre Influence

Publikationen registrerades 2013-04-29. Den ändrades senast 2013-05-30

CPL ID: 176326

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