Experimental study of heat transfer characteristic on jet impingement cooling with film extraction flow

An experimental investigation was carried out to examine the heat transfer characteristics on impingement cooling with extraction flow under stationary condition. The local heat transfer coefficient was measured by the transient method using TLC. Special techniques and devices were developed to make this method feasible and to produce reliable experimental data. The Reynolds number based on the inlet velocity of the jet air and the diameter of impingement hole changes from 2000 to 12,000. Various test models with relative impingement distance H/d = 1.0, 3.0, 6.0 and position of impingement cooling hole = 1/3,1/2 were conducted to get the effects of H/d and f/l. The local Nu on the target surface was measured by a transient method with TLC. Experimental results reveal that the position of impingement cooling hole f/l has great influence on the heat transfer characteristics of the target surface. The averaged Nu of f/l = 1/3 configuration is about 9% higher than that of f/l = 1/2 configuration. It is also found that the maximum local Nu is mostly affected by H/d. And the higher Nusselt number is achieved with smaller H/d, the averaged Nu of H/d = 6 model is about 22%-38% lower than that of H/d = 1 for different Reynolds numbers. (C) 2014 Elsevier Ltd. All rights reserved.