Rotating Wheels - Their Impact on Wind Tunnel Test Techniques and on Vehicle Drag Results

Wickern, Gerhard; Zwicker, K.; Pfadenhauer, Michael

doi:10.4271/970133

Cited by 112 publications

(43 citation statements)

References 3 publications

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“…The effects of wheel rotation and rim design on passenger cars have been the topic of several studies for the past years. References [1,2,3,4,5,6,7,8] are examples of such studies. However, a limited number of publications into the effects of tyre profile and tyre tread are available in the literature.…”

Section: Introductionmentioning

confidence: 98%

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Investigation of the Influence of Tyre Geometry on the Aerodynamics of Passenger Cars

Hobeika¹,

Sebben²,

Landström³

2013

SAE Int. J. Passeng. Cars - Mech. Syst.

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It is well known that wheels are responsible for a significant amount of the total aerodynamic drag of passenger vehicles. Tyres, and mostly rims, have been the subject of research in the automotive industry for the past years, but their effect and interaction with each other and with the car exterior is still not completely understood. This paper focuses on the use of CFD to study the effects of tyre geometry (tyre profile and tyre tread) on road vehicle aerodynamics. Whenever possible, results of the numerical computations are compared with experiments.More than sixty configurations were simulated. These simulations combined different tyre profiles, treads, rim designs and spoke orientation on two car types: a sedan and a sports wagon. Two tyre geometries were obtained directly from the tyre manufacturer, while a third geometry was obtained from our database and represents a generic tyre which covers different profiles of a given tyre size. All geometries were deformed based on measured wind tunnel data under a defined load and rotating conditions of 100 kph.Results have shown that the main grooves consistently lead to a decrease of both drag and lift. The edge pattern however, did not show a clear trend for drag and lift with respect to the different configurations studied, although its influence was always more noticeable on the sports wagon. The larger profile of the generic tyre resulted in higher drag and lift values with relation to the tyres obtained from the manufacturer. For a given rim, a drag difference was observed between two tyre geometries with same profile but different tyre tread. These findings lead to the conclusion that tyre profile, as well as tyre pattern, are important to consider. These results were confirmed by wind tunnel tests. In conclusion, the work of aerodynamic optimization of rims cannot be separated from the tyre itself.

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Section: Introductionmentioning

confidence: 98%

“…Wheels and wheelhouses are shown to contribute to about 25% of the total aerodynamic drag of a vehicle [1]. The wheel rotation creates a wake which interacts with the car exterior as well as with the under body, influencing the drag contribution of both.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Influence of Tyre Geometry on the Aerodynamics of Passenger Cars

Hobeika¹,

Sebben²,

Landström³

2013

SAE Int. J. Passeng. Cars - Mech. Syst.

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“…This technique takes no account for the tunnel floor boundary layer or the absence of effects due to wheel rotation. The presence of the ground plane boundary layer is likely to reduce the measured drag because it effectively shields a portion of the tyres from the approach flow, whereas wheel rotation will have the opposite effect (3)(4)(5)(6)(7)(8)14). Figure 7 shows the variation of absolute drag coefficient with boot spoiler height for the test vehicle fitted with a smooth underfloor.…”

Section: Resultsmentioning

confidence: 99%

“…Early studies of the aerodynamic effects of wheel rotation were reviewed by Cogotti (1). More recently work has been completed by Bonis (2), Mercker et al (3)(4)(5)(6), Wiedemann (7) and Zwicker et al (8). All the authors have shown that total vehicle drag is reduced with rotation of the wheels.…”

Section: Introductionmentioning

confidence: 88%

A Comparison of On-Road Aerodynamic Drag Measurements with Wind Tunnel Data from Pininfarina and MIRA

Good¹,

Howell²,

Passmore³

et al. 1998

SAE Technical Paper Series

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The principal development tool for the vehicle aerodynamicist continues to be the full-scale wind tunnel. It is expected that this will continue for many years in the absence of a reliable alternative.As a true simulation of conditions on the road, the conventional full-scale wind tunnel has limitations. For example, the ground is fixed relative to the vehicle, allowing an unrepresentative boundary layer to develop, and the wheels of the test vehicle do not rotate. These limitations are known to influence measured aerodynamic data.In order to improve the representation of road conditions in the wind tunnel, most of the techniques used have attempted to control the ground plane boundary layer. Only at model scale has the introduction of a moving ground plane and rotating wheels been widely adopted.The Pininfarina full-scale wind tunnel now incorporates the Ground Effect Simulation System which allows testing with a moving belt and rotating wheels. A major feature of this facility is that test vehicles can be easily installed with only minor modifications. This paper compares aerodynamic drag measurements for a large saloon, in various configurations, obtained both in the wind tunnel and on the road. The wind tunnel results are presented for various ground simulations. These are: moving belt with rotating wheels and stationary belt with fixed wheels at Pininfarina, and the conventional fixed ground in the MIRA full-scale wind tunnel. The on-road data is derived from coastdown tests.

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“…Previous research has, for the majority, concentrated on minimising the drag created by the rear end of vehicles, as this can account for up to 70% of the total vehicle drag, as found from a simplified model by Ahmed et al [2]. Fewer publications have focused on wheel and wheelhouse flows although these have been shown to contribute between 20% and 40% of a passenger vehicle's overall drag and strongly influence the rear-end drag, as stated by Hucho [3], Wickern et al [4] and Elofsson and Bannister [5]. Wheels in isolation have been sufficiently documented, incipiently by Morelli [6] to more recently by Croner et al [7].…”

Section: Existing State Of the Artmentioning

confidence: 99%

Investigation of Wheelhouse Flow Interaction and the Influence of Lateral Wheel Displacement

Rajaratnam

Walker

2019

Energies

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The aim of this research was to improve the understanding of the complex flow features found around a wheel and wheelhouse and to examine how the lateral displacement of the wheel affects these features and the production of exhibited pressures and forces. A bespoke rotating wheel rig and accompanying wheelhouse with a fully-pressure-tapped wheel arch was designed and manufactured at Loughborough University. Wind tunnel tests were performed where force and pressure measurements and Particle Image Velocimetry (PIV) data were obtained. The experimental data was used to validate unsteady CFD predictions where a k-ω SST Improved Delayed Detached Eddy Simulation (IDDES) turbulence model was used in STAR-CCM+ (10.04.009, Siemens). The CFD showed good agreement with all trends of the experimental results providing a validated numerical methodology. For both methodologies, a lower amount of wheelhouse drag was found generated when the wheel was rotating. However, the CFD showed that whilst this was the case, total configuration drag had increased. This was attributed to an increase of the wheel and axle drag, illustrated by the change in separation over the wheel itself when located within a wheelhouse and so overcompensating the reduction in body and stand drag. Differences in vortex locations when comparing to previously-attained results were due to differences in housing geometry, such as blockage in the cavity or housing dimensions. Experimental and computational results showed that up until a 10 mm displacement outboard of the housing, overall drag decreased. The reduction in housing drag was credited to a reduction in the size of outboard longitudinal vortex structures. This led to the lateral width of the shear layer across the housing side being narrower. Overall, this study identified that there were potential benefits to be gained when offsetting a wheel outboard of the longitudinal edge of a model housing.

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Rotating Wheels - Their Impact on Wind Tunnel Test Techniques and on Vehicle Drag Results

Cited by 112 publications

References 3 publications

Investigation of the Influence of Tyre Geometry on the Aerodynamics of Passenger Cars

Investigation of the Influence of Tyre Geometry on the Aerodynamics of Passenger Cars

A Comparison of On-Road Aerodynamic Drag Measurements with Wind Tunnel Data from Pininfarina and MIRA

Investigation of Wheelhouse Flow Interaction and the Influence of Lateral Wheel Displacement

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