Local Convective Heat Transfer From a Heated Surface to a Planar Jet of Water With a Nonuniform Velocity Profile

Abstract

Experiments have been conducted on a planar, free surface jet of water to investigate the effects of a nonuniform velocity profile on the local convection coefficient for a uniform heat flux surface. Heat transfer coefficient distributions were measured for heat fluxes ranging from 0.24 to 1.47 MW/m2 and for Reynolds numbers (based on the average nozzle velocity and nozzle width) from 15,000 to 54,000. This range of flow conditions yielded turbulent velocity profiles similar to those of channel flow. Results have been obtained for both single-phase convection and nucleate boiling. Relative to results for a uniform velocity profile, the nonuniform profile was found to enhance heat transfer significantly. However, enhancement is attributed primarily to increased levels of turbulence and only secondarily to changes in the velocity profile.