A numerical study of impingement heat transfer in a confined circular jet

Abstract

Heat transfer characteristics of a submerged circular jet impingement with a confined plate was studied numerically. The continuity, momentum and energy equations were solved simultaneously. FIDAP, a finite element code, was used to formulate and solve the matrix equations for fluid 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 influenced strongly on the surface temperature, shear stress and pressure drop. The peak temperature was observed and gradually moved outward to the rim of the heated circular plate with increasing the Reynolds number, which may be related to flow recirculation region in the channel. It is also noted that the pressure drop increased more than the average heat transfer coefficient as the Reynolds number increased. For Pr=7, the Nusselt number was much more dependent on the Reynolds number than the channel height, and the magnitude of the second peak in the Nusselt number distribution increased as the Reynolds number increased. The local Nusselt number calculated based on a mixing-cup temperature was considerably different from that using the inlet nozzle temperature for H=0.5 and Re=100. The present study showed that the local Nusselt number of a confined submerged jet was significantly larger than that of the unconfined free jet which was available in the literature.