VENTILATED FLOW IN THE UNOBSTRUCTED SPACE BETWEEN COROTATING DISKS INA CYLINDRICAL ENCLOSURE

An experimental investigation has been performed for the ventilated fl ow of air in the unobstructed space between the center pair of four di sks corotating in a fixed cylindrical enclosure. This configuration is of fundamental interest and considerable practical utility in the com puter industry. Time-resolved and time-averaged measurements of the ci rcumferential velocity component were obtained using a laser-Doppler v elocimeter in back-scatter mode. The data were collected along the rad ial 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 x 10(3), 2.22 x 10(4 ), and 2.66 x 10(5)) were investigated for a limited but significant r ange of the Rossby number (\Ro\ < 0.85), including air sucked radially inward (Ro < 0) and air blown radially outward (Ro > 0). The experime ntal data present a challenging target for numerical procedures purpor ting to predict this class of flows. In agreement with earlier prelimi nary calculations performed by Humphrey et al. (1992), the imposition of a radial ventilation condition in the experiments is observed to ha ve 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 kno wing these accurately. These and related findings are discussed with s pecial consideration given to their potential impact on the improved d esign of ventilated disk storage systems.