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ISSN Online: 2377-424X

International Heat Transfer Conference 12
August, 18-23, 2002, Grenoble, France

Enhancement of the Heat Transfer from Flat Surface to Impinging Round Jet Using Triangular Tabs

Get access (open in a dialog) DOI: 10.1615/IHTC12.3010
6 pages

Abstract

This investigation characterized the heat transfer enhancement produced by adding an array of triangular tabs to the exit of a round impinging jet. It was found that the heat transfer produced by the impinging jet could be increased by up to 15% in the region r/D ≤ 2 when the nozzle-to-plate spacing was 2 diameters. The heat transfer enhancement was reduced and more axisymmetric when the nozzle-to-plate spacing was increased to 4 or 6 diameters. When the nozzle-to-plate spacing was 2 diameters the largest heat transfer enhancement occurred in a series of distinct regions surrounding the impingement zone. The number of these regions per tab decreased by a factor of two when the number of tabs in the array was increased from 6 to 10 or 16. Measurements of the velocity field showed these regions corresponded to high-speed regions in the jet created by the tabs. Initially high speed regions formed in all the gaps between the tabs but the high-speed regions between the smaller gaps in the 10 and 16 tab arrays mixed with the main jet by 1.5 diameters downstream of the jet. The high-speed regions created by the tabs had mixed with the main jet by 3 diameters so the heat transfer enhancement at larger nozzle-to-plate distances was caused by the enhanced turbulent mixing created by the tabs.