HEAT-TRANSFER CHARACTERISTICS OF ARRAYS OF FREE-SURFACE LIQUID JETS

In this study, local heat transfer data under arrays of free-surface l iquid jets are measured with a two-dimensional infrared radiometer. Ex perimental measurements were made for three nozzle diameters using a s even-jet staggered and a nine-jet in-line geometric array configuratio n. Nozzle-to-plate spacings of two and five nozzle diameters were inve stigated for four jet center-to-center spacings ranging from two to ei ght diameters in the jet Reynolds number range of 5000 to 20,000. Resu lts show that the stagnation Nusselt number under the central jet is i ndependent of array configuration and jet-to-jet spacing. The differen t interjet flow interaction, as represented by different jet array con figurations (the in-line array and the staggered array with different nozzle-to-nozzle spacings), shows negligible influence on local heat t ransfer under the central jet. Differences in the heat transfer charac teristics for the two nozzle-to-plate spacings investigated were the r esult of an observed transition from confined submerged central jet fl ow to free-surface jet flow as the nozzle-to-plate spacing was increas ed. Secondary maxima in the Nusselt number were observed between the a djacent jets, being a direct consequence of the radial flow interactio n between jets. A correlation for average heat transfer is presented.