Study of Temperature Reduction in Automobile Brake Discs by Forced Convection

The brake system is one of the most important safety systems of the vehicle. So far, several researches are being conducted with the objective of improve its efficiency. In a disc brake, it is the friction between the pads and the rotor the responsible for kinetic energy conversion into heat and brake torque generation. Demanding brake applications, can generate high temperatures levels which can reduce the friction coefficient between pads and rotor, reducing brake efficiency. Thus, the present work aims to evaluate the front disc temperature drop by the installation of a duct on the vehicle frontal bumper to direct the outside air into the wheelhouse This duct has the function to direct the outside air towards to the brake disc. Theoretical studies, Computational Fluid Dynamics (CFD) simulations and experimental dynamometer tests were carried out. CFD analysis was used to obtain data, such as flow rate, output air speed and pressure loss to define the optimized duct dimension and position. The dynamometer was used to compare the rotor temperature increase during a sequence of brake stops with and without the air flow provided by the engineered duct. CFD simulations showed that the duct with outlet restricted diameter has a better efficiency in directing the air into the brake disc than a duct with a continuous section. In addition, the final duct design has showed a good compromise between the output air speed and the head loss. In the experiments performed in dynamometer, it was observed an average brake disc temperature reduction of 6.2% at 36 km/h, 5.7% at 72 km/h and 3.3% at 105km/h for the tests with ventilation compared to without ventilation.