ISSN Online: 2377-424X
International Heat Transfer Conference 12
Enhancement of the Heat Transfer from Flat Surface to Impinging Round Jet Using Triangular Tabs
Sinopsis
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.