Heat/Mass Transfer with Circular Pin Fins in Impingement/Effusion Cooling System with Crossflow

The purpose of the present study is to investigate the local heat/mass transfer characteristics with circular pin fins in the impingement/effusion cooling with an initial crossflow. The results are compared with those for the cases without pin fins and with rib turbulators. The pin fins are installed between two perforated plates and the crossflow passes between these two plates. A blowing ratio is changed from 0.5 to 1.5 for the fixed jet Reynolds number of 10,000. The local heat/mass transfer coefficients on the effusion plate are measured using a naphthalene sublimation method. When circular pin fins are installed in the impingement/effusion system, heat/mass transfer is augmented due to the generation of vortex and wake. Especially, locally low heat/mass transfer regions in front of the effusion hole are reduced. Because pin fins divert the crossflow passing in the injection hole region, the wall jet is less swept away than the case without pin fins, which results in the increase of heat/mass transfer. As the blowing ratio increases, the pin fins lead to higher heat/mass transfer than the case without pin fins. Compared with rib turbulators, the pin fins yield lower average Sh value at M = 1.0 but higher average Sh value at other blowing ratios.