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Research Papers: Flows in Complex Systems

Effect of Side Wind on a Simplified Car Model: Experimental and Numerical Analysis

[+] Author and Article Information
Emmanuel Guilmineau

Laboratoire de Mécanique des Fluides, CNRS UMR 6598, Equipe Modélisation Numérique, Ecole Centrale de Nantes, 1 Rue de la Noë, BP 921001, 44321 Nantes Cedex 3, Franceemmanuel.guilmineau@ec-nantes.frLaboratoire d’Aérodynamique, Conservatoire National des Arts et Métiers, 15 Rue Marat, 78210 Saint Cyr l’Ecole, Franceemmanuel.guilmineau@ec-nantes.fr

Francis Chometon

Laboratoire de Mécanique des Fluides, CNRS UMR 6598, Equipe Modélisation Numérique, Ecole Centrale de Nantes, 1 Rue de la Noë, BP 921001, 44321 Nantes Cedex 3, FranceLaboratoire d’Aérodynamique, Conservatoire National des Arts et Métiers, 15 Rue Marat, 78210 Saint Cyr l’Ecole, France

The geometry of the Willy square-back model is available. Please contact the corresponding author.

J. Fluids Eng 131(2), 021104 (Jan 15, 2009) (12 pages) doi:10.1115/1.3063648 History: Received May 11, 2007; Revised October 14, 2008; Published January 15, 2009

A prior analysis of the effect of steady cross wind on full size cars or models must be conducted when dealing with transient cross wind gust effects on automobiles. The experimental and numerical tests presented in this paper are performed on the Willy square-back test model. This model is realistic compared with a van-type vehicle; its plane underbody surface is parallel to the ground, and separations are limited to the base for moderated yaw angles. Experiments were carried out in the semi-open test section at the Conservatoire National des Arts et Métiers, and computations were performed at the Ecole Centrale de Nantes (ECN). The ISIS-CFD flow solver, developed by the CFD Department of the Fluid Mechanics Laboratory of ECN, used the incompressible unsteady Reynolds-averaged Navier–Stokes equations. In this paper, the results of experiments obtained at a Reynolds number of 0.9×106 are compared with numerical data at the same Reynolds number for steady flows. In both the experiments and numerical results, the yaw angle varies from 0 deg to 30 deg. The comparison between experimental and numerical results obtained for aerodynamic forces, wall pressures, and total pressure maps shows that the unsteady ISIS-CFD solver correctly reflects the physics of steady three-dimensional separated flows around bluff bodies. This encouraging result allows us to move to a second step dealing with the analysis of unsteady separated flows around the Willy model.

Copyright © 2009 by American Society of Mechanical Engineers
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References

Figures

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Figure 14

Force coefficient versus the yaw angle

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Figure 15

Yawing moment versus the yaw angle

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Figure 16

β=30 deg: friction lines (without the cylinder (c))

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Figure 17

β=30 deg: tomography at Xo/L=0.55 (without the cylinder (c))

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Figure 1

Model definition

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Figure 2

Wind tunnel and model

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Figure 3

Boundary layer profile at Xo=−670 mm at the yaw angle β=30 deg

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Figure 4

β=10 deg: pressure coefficient along curve (Pt) versus the mesh

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Figure 5

β=30 deg: 3D view of the wake

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Figure 6

Cross flows for several yaw angles

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Figure 7

β=10 deg: tomography at Xo/L=0.60

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Figure 8

β=20 deg: tomography at Xo/L=0.60

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Figure 9

β=30 deg: tomography at Xo/L=0.55

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Figure 10

β=30 deg: friction lines

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Figure 11

β=30 deg: tomography at Xo/L=0.65

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Figure 12

β=30 deg: tomography at Zo=−14.5 mm

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Figure 13

Pressure coefficient along curve (Pt)

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