Understanding and improving the convective cooling of brake discs with radial vanes

Abstract

Detailed computational fluid dynamics (CFD) analyses of airflow and convective heat dissipation from a standard disc with radial vanes gave vital information regarding its weak points. Heat transfer from vanes is found to be particularly non-uniform, offering the largest scope for increasing local and average values of the coefficient of convective heat dissipation. A relatively simple modification — installation of an additional small vane (per channel, between the existing vanes) — demonstrated the ability to increase convective cooling from the ventilation channels. The radial position of these additional vanes was altered from disc ID towards OD, and best results were obtained with the vanes placed at the channel outlets (OD). An improvement in the total convective cooling (product of the average convective heat transfer coefficient and the entire disc wetted area) of nearly 14 per cent was achieved. In spite of better cooling, the new design has lower mass (air) flow when compared with the baseline design. The results are also presented in the form of Nusselt numbers, enabling their wider use. Conducted validation provided strong confidence in the accuracy of the results when searching for new solutions.

Influence of convective cooling on a disc brake temperature distribution during repetitive braking

“…Due to the fact of complexity of the phenomenon of frictional heat generation, the problem of concurrent fluid flow within the channels of the ventilated type of disc brakes is often analysed in individual studies based on the CFD method [25][26][27][28]. Nonetheless often an average, constant value of the heat transfer coefficient is used at temperature calculations in disc brakes [3,29,30].…”

An X-type lattice cored ventilated brake disc with enhanced cooling performance

“…Again, the lower half distribution is a central symmetry of the upper half relative to the z-axis. For the radial vane brake disc, discontinuous vane material distribution and flow separation near the suction sides of the vanes [14,34] have been reported to cause highly non-uniform heat transfer on ventilated channel walls [34]. However, the local effective heat transfer obtained on the inboard copper foil surface is approximately isotropic along the circumferential direction, as indicated by the approximately concentric contour lines shown in Fig.…”

“…Consequently, the present study focuses on a brake disc rotating in an infinite environment, without considering the aforementioned additional influences. Such a scheme has been adopted in most previous studies and is believed to be reasonable at the preliminary design stage for comparative investigations [4,5,[13][14][15][17][18][19][20][21][22][23][24][25][26]29,31,[33][34][35][36][37][38][39][40]. …”

“…Consequently, this type of brake disc is the most popular choice [16]. Numerous studies have been conducted to characterize its thermo-fluidic characteristics [3,14,[24][25][26][27][28][29][30][31] and to improve its cooling performance by modifying the cross-section and arrangement of radial vanes [17][18][19][32][33][34][35][36]. It is demonstrated that cooling flow turns to the counter-rotating direction with respect to the brake disc axis before entering the ventilated channel.…”

Thermofluidic Characteristics of a Porous Ventilated Brake Disk

“…Due to the Coriolis effect, the incident flow angle to the vane passage becomes high, causing flow separa tion from the leading edge of the vanes. Consequently, a large flow recirculation region forms on the suction side of each vane, which reduces the amount of cooling flow in the ventilated channel [10][11][12][13].…”