Improvement of Convective Heat Dissipation from Commercial Vehicle Disc Brakes by Implementing Geometric Design Alternatives

摘要

Anti-coning ventilated brake rotors offer superior resistance to elastic deformations caused by complex thermo-mechanical loading, compared to conventionally designed brake rotors. While the benefits to the braking system with regards to Noise, Vibration and Harshness (NVH), and driver "feel" characteristics are evident, stress levels in critical regions are typically higher and convective heat dissipation is inferior. The reason for the reduction in cooling characteristics is that air supply is restricted at the inlets of the ventilation channels, as well as at the rotor outer diameter (OD), due to the proximity to the wheel. The flow patterns in the channels are directly affected by this and can considerably change when compared to studies of the rotor without the wheel. The present work utilises Computational Fluid Dynamics (CFD) modelling techniques in studying the convective cooling performance of a reference design. An alternative design is generated, which implements appropriate dimensional changes, leading to reduced mass and improved convective heat transfer coefficients. Despite the relatively low rotation speeds of commercial vehicle (CV) wheels (and therefore rotors), the obtained results show that rotors with a reduced OD and an increased inner diameter (ID) can dissipate heat more effectively, due to better air flow characteristics. This is conducive to lower brake temperatures, thus benefiting rotor and pad wear, therefore reducing vehicle operating costs. An additional benefit of the new design is a mass saving, which is important in decreasing both material cost and vehicle CO_2 emissions.