Abstract:

The heat dissipation capacity of the brake is closely related to the service braking performance of the passenger vehicles， in which the high-performance car has a higher demand for the heat dissipation capacity of the brake in the process of drastic driving. In this paper， a bench test is carried out for a certain carbon ceramic ventilated disc brake assembly. And a general fitting relation is proposed to represent the comprehensive heat transfer of convection and radiation through the calculation of the cooling coefficient of the brake disc in the cooling-down condition， which has important reference value for the quantitative description of the heat dissipation performance of the brake. Subsequently， the computational fluid dynamics （CFD） simulation is conducted in this paper， which discusses the influence of different variables on the heat dissipation characteristics of the brake， and reveals the mechanism of the influence of the dust shield on the heat dissipation of the brake. The results show that the convection heat transfer accounts for more than 75% of the total heat transfer in the cooling-down condition of the brake disk at the mean temperature of 500 ℃ without dust shield， and the convection heat transfer on the outer surface of the brake disc plays a leading role. In addition， when the brake disc is covered by the dust shield， the cooling capacity of the brake decreases significantly due to the increase of the air temperature around the brake disc surface close to the dust shield and the decrease of the mass flow rate in the ventilation channel inside the brake disc. The analysis results of this paper have important guiding significance for the optimization design of the brake cooling duct.

Key words: carbon-ceramic disc brake, ventilation brake disc, cooling coefficient, heat dissipation characteristic, experimental analysis