Impingement Cooling Experiments With Flat Plate and Pin Plate Target Surfaces

Heat transfer experiments were conducted with three (3) different target plate configurations: a baseline copper flat smooth plate, a copper plate model with copper pins and a copper plate model with Teflon pins, to determine average heat transfer coefficients on the flat and pin surfaces for application with different plate materials. For each target plate surface configuration, the heat transfer experiments were conducted with selected impingement orifice plate configurations and with selected spacing between the orifice plate and the heat transfer target plate. The heat transfer results for the baseline copper smooth flat plate were in good agreement with a well-recognized correlation for the flow regions used in the correlation. An analytical procedure, similar to that used by Metzger et al. for pin-fins in coolant channels, was developed to separate the average heat transfer coefficients on the flat and pin surfaces. The results with the copper pins showed modest increases of approximately 35 percent in heat transfer at lower Reynolds numbers, decreasing with increased Reynolds number. Application of the experimental results to an analysis for high-pressure engine conditions with modest thermal conductivity materials showed that the overall heat transfer coefficient can decrease with pin surfaces for some conditions, compared to flat plates.