EXPERIMENTAL STUDY OF HEAT TRANSFER FROM A DISCRETE SOURCE TO A CIRCULAR LIQUID JET WITH ANNULAR COLLECTION OF THE SPENT FLUID

Experiments have been performed to determine average convection heat transfer coefficients for axisymmetric, liquid jet impingement, with annular collection of the spent fluid. Measurements were performed for a small, circular healer of fixed diameter (D = 22.2 mm), but for a range of jet diameters (4.42 <= d <= 9.27 mm), nozzle-to-heater spacings (0.25 <= S/d <= 6), and confining wail diameters (22.2 <= D(c) <= 38.1 mm). Two different liquids, water (Pr approximate to 7) and a dielectric fluorocarbon (Pr approximate to 25), were employed to study Prandtl number effects, and flow rates were varied to provide laminar and turbulent jets over the Reynolds number range 1000 less than or similar to Re(d) less than or similar to 40,000. The effect of nozzle-to-heater separation was found to be negligible for laminar jets, while, for turbulent jets, significant heat transfer enhancement could be realized by reducing the separation distance in the range S/d less than or similar to 1. The effect of the confining wail was discernible only for small values of D(c) and was manifested by a reduction in heat transfer with decreasing D(c). Limited agreement was obtained between the dolo of this study and existing correlations for confined and unconfined jets.