Editorial Type:
Article Category: Research Article
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Online Publication Date: 01 Jun 2009

Enhancement of Tire Durability by Considering Air Flow Field5

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Page Range: 103 – 121
DOI: 10.2346/1.3130986
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Abstract

Rolling tire performance is frequently affected by multiple physics. For instance, dry handling is influenced by the tire temperature as a consequence of the heat generation by material viscosity and the heat transfer to ambient air. The general phenomenon is complex and even interactive in that the elasticity parameter affecting tire deformation is a function of the temperature and that the temperature depends considerably on the air flow on tire surface.

This paper refers to connecting the different physics of outside air flow and thermomechanical system of tire. Especially, the heat transfer across tire surface is focused from the viewpoint of thermofluid dynamics. Macroscopic flow turbulence to accelerate the heat transfer is studied in a case study of the run-flat tire, where high temperature due to very large deformation is of a key issue. Numerical simulation is conducted in parallel to experimental works in assessing heat flow and temperature on the surface. It is shown that the proposed geometry of rib sidewall reduces the tire temperature and improves the tire life remarkably.

Keywords: tire; multiphysics; heat transfer; fluid-structure interaction; computational fluid dynamics; turbulence; separated flow; thermal analysis; viscoelasticity; run-flat tire
Copyright: The Tire Society
FIG. 1.
FIG. 1.

Relating physics in tire mechanics.

FIG. 2.
FIG. 2.

Thermofluid system.

FIG. 3.
FIG. 3.

FE model for RANS analysis (7247 two-dimensional elements).

FIG. 4.
FIG. 4.

FE model for LES analysis (approximately 1.4×106 three-dimensional elements).

FIG. 5.
FIG. 5.

The setup of unidirectional flow experiment: (a) a side view, (b) a close-up, and (c) a typical thermograph image.

FIG. 6.
FIG. 6.

Experimental setup for measuring the heat transfer across tire sidewall surface.

FIG. 7.
FIG. 7.

Surface geometry definition.

FIG. 8.
FIG. 8.

Relation between β∗ and p/h by experiments.

FIG. 9.
FIG. 9.

Time-averaged temperature contour computed by RANS for the flow over: (a) flat surface and (b) pitched ribs (w=1 mm, h=2 mm, and p=24 mm).

FIG. 10.
FIG. 10.

Temperature distribution for one pitch on bottom surface (h=2 mm, w=1 mm): (a) by RANS and (b) by experiment.

FIG. 11.
FIG. 11.

Relation between xmin/h and p/h obtained by experiments.

FIG. 12.
FIG. 12.

Instantaneous flow velocity vectors computed by LES: (a) p/h=6, (b) p/h=12, and (c) p/h=16.

FIG. 13.
FIG. 13.

Relation between xr and xmin.

FIG. 14.
FIG. 14.

Definition of evaluation area.

FIG. 15.
FIG. 15.

Distribution of vn (time-averaged and space-averaged in rib length direction).

FIG. 16.
FIG. 16.

Relation between p/h and space- and time-averaged |vn|.

FIG. 17.
FIG. 17.

The run-flat tire.

FIG. 18.
FIG. 18.

The run-flat tire with rib sidewall.

FIG. 19.
FIG. 19.

Heat transfer improvement obtained by rib sidewall.

FIG. 20.
FIG. 20.

Sidewall surface temperature after 39 laps of vehicle test at proving ground: (a) normal sidewall and (b) rib sidewall.

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