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Abstract：
The brake disc of vehicles allows the brake caliper to clamp it for braking the vehicles through a friction action, during which the kinetic energy is converted into heat energy. When the vehicles are running at a normal speed, the brake pad and brake disc are actuated at approximate 100~180 ℃, or even up to 180~400 ℃ in the event of high-speed running, primarily due to the friction between them. The friction is proportional to the product of the friction coefficient and the positive pressure applied vertically to the frictional surface. A larger friction coefficient means a larger frictional force; however, the friction coefficient between the brake pad and brake disc will decrease with growing temperature generated from friction. Thus, a higher braking force and better heat-sinking capability of brake disc will be required to improve the running safety. The heat-sinking of the brake disc is conducted through heat exchange of ambient air to improve the heat transfer efficiency and running stability, while a larger surface area of brake disc is required, or otherwise forced cooling will be effected at the center of the brake disc to promote the brake disc to increase the authenticity and accuracy; then a ventilating disc of the same size is fabricated by bakelite to conduct experiment with this radial rotary duct, and analyze the heat flux in the unit area of the cooling channel, so as to learn the heat transfer distribution and influences of temperature measurement points in the cooling channel within the rotary flow field. The experimental results can provide further understanding on the heat transfer characteristics of ventilating disc of brake disc at various speeds.
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