Many disc brake designs are required to perform a series of stops and accelerations within a limited period of time in a harsh thermal environment. This type of brake test scenario represents the worst case temperature profile for the brake in real-world usage. Simulation of this multi-stop scenario is essential for predicting and comparing different brake disc geometries in order to maximize cooling performance. An accurate simulation requires detailed effects of all three modes of heat transfer (radiation, conduction, and convection). Capturing the details of convection heat transfer requires a high resolution CFD (computational fluid dynamics) model of the airflow around the brake including front fascia, suspension, dust shields, wheels, and other vehicle front-end components. This type of CFD model does not lend itself well to long transient analysis; instead, we couple the results of several steady-state CFD models representing different speeds during one stop cycle to a long transient thermal model representing the full multi-stop scenario. The thermal model directly predicts the radiation and conduction heat transfer based on surface and volume mesh of the brake; convection heat transfer is included based on the predicted CFD results. This coupled modeling process balances computational efficiency with model complexity. The results of the coupled process are demonstrated on a typical brake and thermal model results are compared to measured data for verification.
Jussila, Antti; Kush, Alexandra; Packard, Corey; Pryor, Joshua; - ThermoAnalytics, Inc.