Heat Transfer Analysis of a 50% Scale Formula 1
Wheel Assembly

Abstract

The heat transfer of a 50% scale model F1 wheel assembly has been analysed experimentally with hot films,
using a brake cooling test rig for internal analyses, and the Durham University wind tunnel for combined
internal and external analyses. Computational analysis using the Exa PowerFlow CFD software was undertaken
as both a correlation exercise, and to complement the experimental results, providing insight into the flow
characteristics within the wheel assembly.

The systematic error within the system was evaluated by determining the level of heat transfer at zero-flow
conditions, which led to the conclusion that varying flow application method does not affect the disc heat
transfer coefficient. Experimental and computational results were used to derive the Nusselt number
equation, with the wind tunnel disc revealing a Reynolds number exponent of 0.87, a figure closely correlating
to literature. Results for the sidewall presented a range of heat transfer values, to which a combined model fit
was applied.

Investigations into unmatched tyresurface velocity and flow velocity determined that 77% of the convective
heat transfer experienced at the sidewall was due solely to the tyre’s rotation. The level of applied air-flow, did however, affect the rate of heat transfer. Internal of the upright, comparison of results for a blocked and open Inlet scoop found the Inlet scoop to be the predominant source of cooling to the disc.

Wind tunnel heat transfer coefficientresults for the tyresidewall displayed a relationship to radial position,
with HTC increasing from the central position of the sidewall both toward the internal diameter and external
diameter. The capability of the CFD software to extract heat transfer coefficients was assessed using two
rotational simulation methods; Sliding mesh (physical rotation) and moving reference frame(imposed rotation
through the application of rotational fluid forces), neither of which was able to reproduce the patterns of heat transfer outlined in the wind tunnel results.