Ground Effect Aerodynamics of Race Cars

[+] Author and Article Information
Xin Zhang

Aerospace Engineering, School of Engineering Sciences, University of Southampton, Southampton SO17 1BJ, UK

Willem Toet, Jonathan Zerihan

 BAR Honda F1, Brackley NN13 7BD, UK

Wheels are external to the bodywork in plan view.

Appl. Mech. Rev 59(1), 33-49 (Jan 01, 2006) (17 pages) doi:10.1115/1.2110263 History:

We review the progress made during the last 30years on ground effect aerodynamics associated with race cars, in particular open wheel race cars. Ground effect aerodynamics of race cars is concerned with generating downforce, principally via low pressure on the surfaces nearest to the ground. The “ground effect” parts of an open wheeled car’s aerodynamics are the most aerodynamically efficient and contribute less drag than that associated with, for example, an upper rear wing. While drag reduction is an important part of the research, downforce generation plays a greater role in lap time reduction. Aerodynamics plays a vital role in determining speed and acceleration (including longitudinal acceleration but principally cornering acceleration), and thus performance. Attention is paid to wings and diffusers in ground effect and wheel aerodynamics. For the wings and diffusers in ground effect, major physical features are identified and force regimes classified, including the phenomena of downforce enhancement, maximum downforce, and downforce reduction. In particular the role played by force enhancement edge vortices is demonstrated. Apart from model tests, advances and problems in numerical modeling of ground effect aerodynamics are also reviewed and discussed. This review article cites 89 references.

Copyright © 2006 by American Society of Mechanical Engineers
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Figure 1

An example of average race speed evolution since 1965

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Figure 2

An illustration of a race car front wing equipped with end-plates and Gurney flaps, and race car wheels

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Figure 3

An illustration of rear diffusers

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Figure 4

Downforce contours of a generic open wheeled race car: (a) front down-force coefficient and (b) rear downforce coefficient

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Figure 5

Schematic of the moving belt system with a side mounted wheel model

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Figure 6

Image of a race car model in a low speed wind tunnel equipped with a moving belt system

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Figure 7

Schematic of a generic double-element wing in ground effect

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Figure 8

Force behavior of a single element, generic wing with ride height (48): (a) downforce and (b) rate of change in downforce. α=3.45deg, Re=4.5×105.

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Figure 9

Cross-plane LDA survey of edge vortex behind a generic, single element wing at x∕c=1.5 and h∕c=0.224(48): (a) streamwise velocity and (b) velocity vectors. α=3.45, Re=4.5×105. Fixed transition.

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Figure 10

Instantaneous spanwise vorticity, Ωz, contours behind a generic, single-element wing (48). h∕c=0.067. α=3.45deg. Re=4.5×105. Free transition.

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Figure 11

Increase in downforce with Gurneys in freestream and ground effect (58). Re=4.5×105. Free transition.

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Figure 12

Schematic of a bluff body with an upswept aft section to study aerodynamics of diffuser in ground effect

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Figure 13

Downforce versus ride height curve of a generic diffuser equipped bluff body (7): (a) downforce and (b) drag. Re=5.4×106. 17deg diffuser.

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Figure 14

Edge vortices inside a 17deg diffuser at h∕d=0.382. Distance to the inlet of the diffuser is 3d. Data obtained with particle image velocimetry.

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Figure 15

Downforce coefficients (67): renormalized ride heights. Re=5.4×106.

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Figure 16

Surface flow visualization on the ramp at maximum downforce (67), Re=5.4×106. Flow from left to right. Picture area corresponds to the ramp area.

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Figure 17

Surface pressure distribution on the centerline of the wheel measured by Fackrell and Harvey (70)

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Figure 18

Surface flow pattern on the stationary Frackell and Harvey geometry (88)

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Figure 19

Volume streamlines on the stationary Frackell and Harvey geometry (88)



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