Abstract
KEYWORDS
Aerodynamics, Wake Analysis, Brakes
ABSTRACT
Vented brake rotors can enable enhanced cooling by acting as centrifugal pumps. Previously published work, both experimentally and using computational fluid dynamics, has focussed on assessing the airflow at the outlet of a rotating brake rotor tested in isolation in still air. This is a different flow environment to the working condition of the rotor. Airflow around the rotor, as a result of the forward movement of the vehicle, will have a considerable effect on its pumping ability. In this work we assess the measured airflow through a straight-vane vented disc for the cases of: (1) isolated disc still air; (2) disc in still air with the wheel on; (3) disc in moving air with the wheel on; and (4) on road simulation using a ¼ car. Recent developments in robust instrumentation, involving multi-hole pressure probes with a frequency response to 2,000Hz, have enabled such measurements to be made in the relatively harsh environment around a rotating wheel and this technique is described. Both time-averaged and real-time measurements and results are presented. Spectral analysis indicated vortex shedding occurring behind the vanes. For tests (3) and (4) vent airflow was a function of both rotational speed of the rotor and angular position around the rotor, with the volume flowrate of air significantly lower than that measured in still air tests.