Experimental investigation on jet impingement heat transfer for micro-channel

Experiments are conducted to investigate the flow and heat transfer characteristics of inner cooling channel with real engine sizes. The diameter of impingement holes and film holes are 0.3 mm, 0.4 mm and 0.5 mm, respectively. Ratios of the distance between the impingement plate and the target plate to the impingement hole diameter (H/D) are 2, 2.5 and 3.0, respectively. Hole pitch to diameter ratios (P/D) are 5 and 10, respectively. The Reynolds number varies from 1000 to 10000, Knudsen number is equal to the Knudsen number in real working condition of engine. The thermodynamic characteristics of micro-scale impingement channels with different geometry are studied. The results show that with the same Reynolds number, average heat transfer coefficient of channel increases as the hole diameter decreases, and it decreases as the magnitude of H/D or P/D increases, and the empirical correlation has been fitted.