Computational Flow Analysis of Brake Cooling

Air flow around the front brake assembly was computed using STAR-CD version 2.300, a commercial Computational Fluid Dynamics (CFD) code in order to explore the possibility of using this technique as a design tool. The primary objective in a brake corner assembly design is to maximize air cooling of the brake rotor. It is a very challenging task that requires experiments that are both expensive and time consuming in order to evaluate and optimize the various design possibilities. In this study, it is demonstrated that the design procedure can be shortened and made less expensive and be accurate using flow simulations. Accordingly, the air flow around the front brake assembly was computed for three different designs and for three different car speeds.

A computational mesh was built using PROSTAR, the STAR-CD pre and post-processor. The three-dimensional mesh had almost 900,000 cells. All geometrical components were modelled. The boundary conditions were consistent with a car travelling on the road at constant speed. The average heat transfer coefficients on the ventilated brake rotor and the wheel were calculated from the flow simulations through the Reynold's analogy. Using a thermal model, the cooling coefficient of the brake rotor was calculated using the average heat transfer coefficients. The results were compared with experimental data. The agreement with experimental data was very encouraging. For most cases, the computationally determined cooling coefficients agreed with the experimental data to within 3%.