A NUMERICAL STUDY OF IMPINGEMENT HEAT-TRANSFER IN A CONFINED CIRCULARJET

Heat transfer characteristics of a submerged circular jet impingement with a confined plate was studied numerically. The continuity, momentu m and energy equations were solved simultaneously. FIDAP, a finite ele ment code, was used to formulate and solve the matrix equations fdr fl uid elements. The effects of channel height and Reynolds number on the local Nusselt number were considered in the range of H=0.5-1.5 and Re =100-900, respectively. It was found that the channel height influence d strongly on the surface temperature, shear stress and pressure drop. The peak temperature was observed and gradually moved outward to the rim of the healed circular plate with increasing the Reynolds number, which may be related to flow recirculation region in the channel. It i s also noted that the pressure drop increased more than the average he al transfer coefficient as the Reynolds number increased. For Pr=7, th e Nusselt number was much more dependent on the Reynolds number than t he channel height, and the magnitude of the second peak in the Nusselt number distribution increased as the Reynolds number increased. The l ocal Nusselt number calculated based on a mixing-cup temperature was c onsiderably different from that using the inlet nozzle temperature for H=0.5 and Re=100. The present study showed that the local Nusselt num ber of a confined submerged jet was significantly larger than that of the unconfined free jet which was available in the literature.