Heat transfer enhancement by X-type lattice in ventilated brake disc

We introduce an improved design of the X-type lattice cored ventilated brake disc proposed in a previous study. Several annular sector X-type lattice components are integrated into the ventilated channel. Detailed thermo-fluidic characteristics of this new brake disc are explored by experiments and numerical simulations. Experimental results reveal that the new brake disc exhibits better thermal uniformity than the preliminary X-type brake disc, leading to approximately uniform reduction of rubbing surface temperature relative to a prevalent radial vane brake disc. Within the typical operating range of a passenger vehicle (i.e., 200-1000 RPM), the new brake disc provides 18-21% and 7-17% higher steady-state overall cooling capacity than the radial vane and preliminary X-type brake discs, respectively. Numerical results reveal that replacement of radial vanes by the X-type lattice reduces pumping capacity by approximately 40%, deteriorating therefore local heat transfer on the inner surface, the outer rim surface, the inner rim surface and the rubbing surface of the rubbing discs. However, the unique topology of the X-type lattice results in successive interruption and redevelopment of flow and thermal boundary layers, flow impingement on upstream surface of each ligament, and stronger flow mixing in conjunction with an enlarged core surface area. Hence, heat transfer on core surface is substantially improved, which acts as the dominant mechanism for enhanced overall cooling performance of the new brake disc. (C) 2016 Elsevier Masson SAS. All rights reserved.