Ventilated Flow in the Unobstructed Space Between Corotating Disks in a Cylindrical Enclosure

Abstract

An experimental investigation has been performed for the ventilated flow of air in the unobstructed space between the center pair of four disks corotating in a fixed cylindrical enclosure. This configuration is of fundamental interest and considerable practical utility in the computer industry. Time-resolved and time-averaged measurements of the circumferential velocity component were obtained using a laser-Doppler velocimeter in back-scatter mode. The data were collected along the radial coordinate direction on the midplane between the disks (Z = 0) and along the axial coordinate at two radial locations (R = 0.71 and 0.86). Three values of the Reynolds number (Re = 2.73 × 103 , 2.22 × 104 , and 2.66 × 105 ) were investigated for a limited but significant range of the Rossby number (|Ro| < 0.85), including air sucked radially inward (Ro < 0) and air blown radially outward (Ro > 0). The experimental data present a challenging target for numerical procedures purporting to predict this class of flows. In agreement with earlier preliminary calculations performed by Humphrey et al. (1992), the imposition of a radial ventilation condition in the experiments is observed to have a pronounced effect on the inter-disk flow characteristics. However, the predicted results were found to depend strongly on the boundary conditions imposed and present measurements show the importance of knowing these accurately. These and related findings are discussed with special consideration given to their potential impact on the improved design of ventilated disk storage systems.