Turbulent Heat Transfer Augmentation Using Microscale Disturbances Inside the Viscous Sublayer

[+] Author and Article Information
H. Kozlu, B. B. Mikic, A. T. Patera

Massachusetts Institute of Technology, Department of Mechanical Engineering, Cambridge, MA 02139

J. Heat Transfer 114(2), 348-353 (May 01, 1992) (6 pages) doi:10.1115/1.2911282 History: Received November 08, 1989; Revised July 11, 1991; Online May 23, 2008


We report here on an experimental study of heat transfer augmentation in turbulent flow. Enhancement strategies employed in this investigation are based on the near-wall mixing processes induced in the sublayer through appropriate wall and near-wall streamwise-periodic disturbances. Experiments are performed in a low-turbulence wind-tunnel with a high-aspect-ratio rectangular channel having either (a) two-dimensional periodic microgrooves on the wall, or (b) two-dimensional microcylinders placed in the immediate vicinity of the wall. It is found that micro-disturbances placed inside the sublayer induce favorable heat-transport augmentation with respect to the smooth-wall case, in that near-analogous momentum and heat transfer behavior are preserved; a roughly commensurate increase in heat and momentum transport is termed favorable in that it leads to a reduction in the pumping power penalty at fixed heat removal rate. The study shows that this favorable performance of microcylinder-equipped channel flows is achieved for microcylinders placed inside y+ ≃20, implying a dependence of the optimal position and size on Reynolds number. For microgrooved channel flows, favorable augmentation is obtained for a wider range of Reynolds numbers; however, optimal enhancement still requires a matching of geometric perturbation with the sublayer scale.

Copyright © 1992 by The American Society of Mechanical Engineers
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