Experimental and numerical investigation of jet impingement cooling using extended jet holes

In this study, jet impingement cooling on flat surface was investigated experimentally. The aim of this study is to elucidate the effect of extended jet holes on the heat transfer performance of the in-line array jet impingement configuration. The studies were performed under fully turbulent flow condition (16250 <= Re <= 32500). Local Nusselt number (Nu) distribution on the surface of interest was obtained experimentally by using Transient Liquid Crystals (TLC) method. Numerical investigations were conducted as the same configuration with the experimental method to explore the flow and heat transfer characteristics. SST k-omega with low-Re correction turbulence model was used for solving turbulence equations. Experimental and numerical studies were conducted on 1 x 6 (in-line array) jet impingement cooling configuration. Dimensionless jet to jet spacing (X-n/D-j), dimensionless jet plate to target plate spacing (Z/D-j) and dimensionless target plate width (Y/D-j) were taken as 5.0, 6.0 and 6.0, respectively. Five different G(j)/D-j= (1.0, 2.0, 3.0, 4.0 and 5.0) were investigated and the results were compared with orifice plate jet impingement configuration (Z/D-j=G(j)/D-j=6.0). Average and local Nu number distributions, pressure drop of the system, flow characteristics and Performance Evaluation Criterion (PEC) were examined in detail. Numerical results were compared with the experimental data and it was obtained that SST k-omega turbulence model was able to accurately predict the average and local Nu number distributions on the surface of interest. The maximum average and local Nu numbers were obtained on the condition of G(j)/D-j=2.0. Furthermore, PEC shows that the most feasible dimensionless nozzle to target plate gap was G(j)/D-j=2.0 at all Re numbers. (C) 2020 Elsevier Ltd. All rights reserved.