Heat Transfer and Flow Performance of Impingement and Impingement/Effusion Cooling Systems

Abstract

The current experimental study is made to investigate the heat transfer characteristics and pressure losses for both impingement and impingement/effusion cooling systems. The experiments are carried out on a metal test plate. The numerical work is made to analyze the flow behavior in the test section. The benefit of introducing the present experimental method is the capability of investigating and analyzing the performance of both impingement and impingement/effusion cooling systems by the same test rig. The impinging jet device configurations are designed as inline round multihole arrays with jet to jet spacing of 4 jet hole diameter. The effusion holes configurations are inline round multi-hole arrays. Staggered arrangement between jet and effusion holes is maintained. The Jet Reynolds numbers (Re j ) of 5000 to 15000 and jet height to diameter ratio ( H D ⁄ ) of 1.5, 2.0, and 3.0 are maintained. For impingement/effusion case, the best wall cooling effectiveness is obtained at (H D ⁄ = 2), and maximum increment in the wall cooling effectiveness over that of impingement case is 23% at (Re j = 5000), 16 % at (Re j = 7500), and 14% at (Re j = 15000). Jet spacing in impingement case and blowing ratio in impingement/effusion case show an evident effect on the discharge coefficients.