Study of a segmented ventilation system of the brake disc and determination of the aerodynamic and heat exchange characteristics of the airflow

Abstract

This study aims determine a relationship between the aerodynamic and heat exchange characteristics of the air flow in a segmented ventilation system of the brake disc with improved heat dissipation in the boundary layer of the air flow. Classical equations of heat and mass transfer in the boundary layer of the air flow cooling the brake disc ventilation chamber were used. The cooling performance of the system was assessed using the method of similarity. The obtained theoretical findings were confirmed by CFD-modelling. Mathematical models were developed for vented discs with both continuous grooves and slotted grooves. A criterion for assessing the performance of brake disc ventilation systems was proposed, consisting in turbulization of the air flow inside the device under study. According to the obtained analytical dependencies, a 20-fold acceleration of the air flow decreases the turbulization parameter by 1.24 times. An increase in the temperature difference in the boundary layer by 8 times leads to an increase in the turbulization parame-ter by 86.2 times. Using the criterion proposed for assessing the work performance, the aerodynamic and heat exchange characteristics of the system under study were calculated. As a result, a relationship between the design parameters of the segmented ventilation system and improved heat dissipation in the boundary layer of the cooling air flow is proposed. The conducted CFD modelling confirmed the aerodynamic characteristics of the system under study obtained theoretical-ly. This mathematical model together with the turbulization parameter can be used when both developing modern vented brake discs and assessing the existing cooling systems of friction units in order to minimize the possibility of reduced heat exchange processes.