Title: Effects of dimple depth and Reynolds number on the turbulent heat transfer in a dimpled channel

Authors: Young Ok Lee, Joon Ahn, Joon Sik Lee

Addresses: Korea Power Engineering Company, Yongin 449-713, Korea. ' Korea Institute of Energy Research, Daejeon 305-343, Korea. ' School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-742, Korea

Abstract: A Large Eddy Simulation (LES) has been conducted for the flow and heat transfer in a dimpled channel. Two dimple depths of 0.2 and 0.3 times of dimple print diameter (=D) have been compared at the bulk Reynolds number of 20,000. Three Reynolds numbers of 5000, 10,000 and 20,000 have been studied, while the dimple depth is kept as 0.2 D. With the deeper dimple, the flow reattachment occurs father downstream inside the dimple, so that the heat transfer is not as effectively enhanced as the case with the shallow ones. At the low Reynolds number of 5000, the Nusselt number ratio is as high as those for the higher Reynolds number, although the value of heat transfer coefficient decreases because of the weak shear layer vortices.

Keywords: dimpled channel; large eddy simulation; LES; turbulent heat transfer; pressure drop; dimple depth; turbulence; shear layer vortices; flow modelling; gas turbines.

DOI: 10.1504/PCFD.2008.021319

Progress in Computational Fluid Dynamics, An International Journal, 2008 Vol.8 No.7/8, pp.432 - 438

Published online: 19 Nov 2008 *

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