Heat Transfer Enhancement of Jet Impingement on a Flat Plate Attached by a Porous Medium with a Center Cavity
Jet impingement heat transfer on a target plate covered with a thick porous layer with or without a cylindrical center cavity is experimentally investigated using the transient liquid crystal technique. Based on the results of jet impingement on a bare flat plate, heat transfer enhancement due to the attachment of porous medium is assessed. The varying parameters in the experiments include the nozzle-to-plate distance, jet Reynolds number, jet-to-cavity diameter ratio, and the cavity depth. Results of Nusselt number distribution, stagnation-zone Nusselt number, and averaged Nusselt number over a region of 3 times the hole diameter are documented. Experimental results show that the attachment of the porous layer with a center cavity can either hamper, or effectively enhance the jet impingement heat transfer over a flat plate. The maximum enhancement occurs at jet Reynolds number of 12400 when the cavity is a through hole and the cavity has the same diameter as the jet. The stagnation-zone Nusselt number increases 58.3% and the averaged Nusselt number increases 77.5% at the maximum enhancement condition. On the other hand, the addition of the thick porous layer without a center cavity gave rise to severe adverse effect on jet impingement heat transfer.
Andreas Öchsner, Graeme E. Murch, Ali Shokuhfar and João M.P.Q. Delgado
P. S. Wu et al., "Heat Transfer Enhancement of Jet Impingement on a Flat Plate Attached by a Porous Medium with a Center Cavity", Defect and Diffusion Forum, Vols. 297-301, pp. 427-432, 2010