Analysis of air flow and heat dissipation from a high performance passenger car front brake rotor

The increasing demand from the consumer for higher levels of refinement from their passenger
vehicles has put considerable pressure on the automotive industry to produce ever quieter cars. In
order to prevent the occurrence of many forms of brake noise, especially judder and drone, excessive
heating of the brake disc must be avoided, whilst minimising temperature variations across the rotor.

In order for this to be achieved the brake rotor must be designed such that it ensures sufficient uniform
heat dissipation and thermal capacity.
In high demand braking applications vented discs consisting of two rubbing surfaces separated by
straight radial vanes are normally employed as they utilise a greater surface area to dissipate heat.
Within this paper the convective heat dissipation from a high performance passenger car front brake
disc has been investigated using computational fluid dynamics (CFD). The results obtained have
been validated by those obtained in preliminary vehicle testing at Millbrook test facility. The
computational model shows adequate correlation to the test results; overpredicting the average heat
transfer coefficient by 18%. The CFD analysis enabled a detailed insight into the air flow and heat
transfer distributions, that was not possible during the vehicle test regime