Experimental investigation on analogy principle of conjugate heat transfer for effusion/impingement cooling

Abstract The previous theoretical work has presented the importance of temperature ratios Tg/Tc in scaling overall cooling effectiveness and proposed several matching principles for scaling overall cooling effectiveness. These matching principles were experimentally validated on the flat plate with impingement/effusion cooling. Tested conditions included four temperature ratios (Tg/Tc = 1.1, 1.2, 1.3 and 1.98), three blowing ratios (M = 0.46, 0.9 and 1.8) and three momentum flux ratios (M = 0.1, 0.4 and 1.6). All cases had matched mainstream side Biot number and Reynolds number. The 2D contours of overall cooling effectiveness were measured by using IR thermography. The results indicate that matching momentum flux ratio provides acceptable matching performance of overall cooling effectiveness for combining effusion and impingement cooling scheme, in spite of the different temperature ratios among these cases. Different from the results of matching momentum flux ratio cases, decrease in temperature ratio is found to significantly increase the overall cooling effectiveness for matching blowing ratio cases. Similar matching results are also observed in pure effusion cooling scheme. Nevertheless, at small momentum flux ratio, this matching method is not recommended for pure effusion cooling scheme due to the notable influence of film cooling effectiveness on scaling overall cooling effectiveness.