Convective heat transfer from a rotating disc in a transverse air stream.

The variation in the local radial heat transfer coefficient is reported for a disc rotating in still air up to 1650 r.p.m. and in a transverse or crossflow air stream of speeds up to 33m/s. These measurements have been made with the aid of a small sensor, using thermistors as heating elements. It is found that the heat transfer coefficient is governed by the main air flow, the rotation of the disc resulting in a small upward perturbation on this level. Tests with different disc aspect ratios, simulated by the disc protruding from a leading edge shroud, show that the radial distribution is greatly modified, but again the main air stream dominates the process. A thin film sensor has been developed to monitor the fluctuations in the heat transfer coefficient about the mean level as the disc rotates in the air stream. The local effects of rotation are examined closely. The velocity distributions around the stationary and rotating disc in still air and a transverse flow are presented. The experimentation is finally extended to the case of a simple train wheel shape, thus attempting to model the convective heat dissipation for the condition of train wheel braking.