Experimental study of convective heat transfer in standard and cross-drilled brake discs with radial vane and X-lattice cores

To improve the cooling performance of disc brake systems, cross-drilled holes penetrating across the rubbing discs are separately introduced into a commercial radial vane brake disc (as reference) and a novel X-lattice cored brake disc. Prototype samples of both the reference and cross-drilled brake discs are fabricated. A rotating test rig is designed and constructed to characterize and compare the cooling performance of the brake discs with infrared thermography. Within the typical operating range of a vehicle, e.g., 200-1000 rpm, the experimental results show that the introduction of cross-drilled holes can substantially enhance brake disc cooling. For the radial vane brake disc, the overall Nusselt number is enhanced by 31%-44%; for the X-lattice cored brake disc, the cross-drilled holes only lead to 9%-18% enhancement. As the radial vane brake disc and the X-lattice cored brake disc with cross-drilled holes exhibit similar cooling performance, flow through the cross-drilled holes has a more prominent effect on the former than the latter. Corresponding fluid flow and heat transfer mechanisms underlying the enhanced heat transfer by cross-drilled holes and the different effects of cross-drilled holes on the two distinct brake discs are explored. The experimental comparison and the thermo-fluidic physics presented in this paper are beneficial for engineers to further improve disc brake cooling.