Heat transfer characteristics of laminar slot jet arrays impinging on a constant target surface temperature

In the present study, heat transfer from a constant temperature plate which is impinged by an array of air-slot jets is investigated. The effects of number of slot jets, width and jet-to-jet spacing on the local Nusselt number are studied for different jet Reynolds numbers and jet-to-plate spacings. The study is focused on low Reynolds numbers ranging from 234 to 470, jet-to-plate spacings from 26.4 to 27.6 mm, slot width in the range of 2-5 mm, and jet-to-jet spacings from 2 to 3 mm. The local Nusselt number is obtained from visualized temperature fields of infinite fringe interferograms by using a Mach-Zehnder Interferometer (MZI). Average and stagnation Nusselt numbers are correlated as a function of independent dimensionless parameters for single jets and three different jet arrays tested with different jet-to-jet spacings and width values. Although the average Nusselt numbers are relatively insensitive to the jet-to-jet spacing, they increase significantly with increments of Reynolds number as well as jet width for all considered cases. However, stagnation Nusselt is directly proportional to slot width and the Reynolds number changes for single and triple jets; distinct behavior is seen for double and quadruple jets, where the number decreases with the increase in jet-to-jet spacing, in contrast to triple jets. Numerical analyses, employing finite volume base code, are in good agreement with the measured experimental results. (C) 2014 Elsevier Ltd. All rights reserved.