Convective heat dissipation from a wheel-hub-mounted railway brake disc

Abstract

Air flow and convective heat dissipation from a wheel-hub-mounted railway brake disc were studied using computational fluid dynamics (CFD). The analyses enabled detailed insight into air flow, temperature, speed, pressure, and convective heat transfer coefficient distributions, never before available to a brake designer. Such results are practically impossible to experimentally obtain at reasonable cost. Particularly interesting finding is the existence of relatively considerable secondary flow — circumferential flow behind the vanes. Although this effect may reduce air pumping, and therefore radial air speed, it increases turbulence by promoting airflow between channels. Average values of the convective heat transfer coefficients obtained using CFD are practically identical to the experimental values derived from cooling tests performed on dynamometer and spin rig. Compared with other railway disc designs, this disc demonstrates exceptionally good convective cooling characteristics, in particular considering its size and investigated operating condition (rotation in still air). The computational studies of air flow and heat dissipation characteristics are an excellent base for development work in improving existing and generating new disc designs with high heat dissipation characteristics. Future work is concentrated on conducting additional analyses of the current disc design, in order to investigate the most effective ways of maximizing convective cooling.