Experimental investigation of the cooling characteristics of a monobloc cast iron brake disc with fingered hub

Abstract

The paper compares heat dissipation characteristics of two interchangeable ventilated brake discs, a standard solid hub and a newly developed fingered hub version, both single piece cast designs. The tests were conducted on a specially developed Thermal Flow Rig, which enables disc induction heating to 450°C and cooling for a range of rotational and air speeds, in parallel and angular cross flow. The Rig facilitated very accurate and repeatable experiments to be conducted for numerous combinations of operating conditions. From the recorded cooling curves, average heat transfer coefficients for convection and radiation were extracted and the results also presented in a generic form, using Nusselt numbers. The fingered design demonstrated superior convective heat dissipation, with the improvements varying depending on the rotational speed, air cross flow velocity and angle, as well as disc temperature. The gains were ranging from 3.5% to over 20%. The fingered design is 8.5% lighter and being a single piece cast disc, it remains inexpensive to mass produce.