Design, Set-up, and Validation of an Aerodynamic Bench for Wheel Corner Flow Investigation in Vented Brake Discs Testing

EB2020-STP-002
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Abstract

Brake disc cooling is strongly affected by the aerodynamic condition surrounding the system and especially by the flow at the ventilation channels inlet. Aero-thermal performance of brake discs is usually tested using a dyno bench in which the aerodynamic field is not representative of the one in the wheel corner of car vehicles. The purpose of this study is to design a dyno bench configuration, called aero-dynamic bench, whose airflow replicates the cooling distribution seen in a vehicle wheel corner. A carbon-ceramic brake disc and an aluminum caliper of a sports car are considered for the design. The work can be summarized into three steps. The first step consists of computational fluid dynamic analysis of the dyno bench changing the cooling pipes position and adding some car components (e.g. rim, wheel bearing, wheel hub) to be representative of the vehicle. The second step involves the realization of the new dyno bench facility starting from the standard one and calibrating the air supply systems. Third, the flow field at the outlet of the ventilation channels is measured traversing a two-component Laser Doppler Velocimeter (LDV) system as well as a hot-wire anemometry (HWA) system for cross-validation at a fixed rotational speed of 1000 rpm. For comparison purposes, tests were also run on the original rig set-up, i.e. with the brake disc rotating in still air without any additional element. Also, experimental measurements are compared with fluid dynamic simulations to check the correlation between tests and the numerical model. Experimental results are qualitatively in line with CFD analysis and reveal that installing the brake disc in the wheel corner results in a vented air mass flowrate reduction. Moreover, the presence of forced convection, compared with the disc auto-ventilation condition, makes the flow exiting the disc channels more uniform as well as with a reduced turbulence intensity level.

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