A Numerical and Experimental Study on the Flow and Heat Transfer Characteristics in Co-Rotating Disk Systems.

Abstract

The flow between parallel disks has its unique features because of the radius effect. When the disks are set into motion, the angular momentum transport from the rotating disks to the fluid makes the flow complicated through centrifugal force and eventually yields enhancement of heat transfer. In this study, the characteristics of the flow and of the heat transfer in stationary and in rotating disk systems were analyzed numerically and experimentally. In the numerical analysis, the SIMPLER method was applied to the laminar and to the turbulent flow with a k-(epsilon) model. Some improvement was made to the conventional algorithm for faster convergency. The analysis revealed detailed profiles of velocity and pressure distribution and the mechanism of the heat transfer enhancement of the rotating flow. Also the effects of rotation number, Reynolds number, Pr and tl number and geometry on the flow field and on heat transfer were investigated. A conventional method for experimental determination of heat transfer performance, namely the single blow technique, was modified for better accuracy and the merits of the new method were discussed. Average Nusselt numbers were measured experimentally in the Reynolds number range of 500 to 4000 with disk rotation speeds from zero to 3600 RPM. Theory compared qualitatively well with experimental results in heat transfer performance. The discrepancy between them was attributed to the nonidentical geometrical and operating conditions.