| Abstract: | Abstract: Results of numerical simulation of the flow and heat transfer characteristics for a semi-confined cluster of laminar air jets impinging normally on a plane wall are presented. A central jet is surrounded by four equally spaced jets of the same configuration. Both circular and noncircular nozzles are considered. The nozzle footprint is displayed in the static pressure, temperature, and local Nusselt number contours on the impingement surface only for relatively short nozzle-to-surface distances. The heat transfer characteristics and performance of circular and noncircular nozzles are compared. It is observed that the Nusselt number based on property values at the jet temperature is relatively insensitive to the temperature difference between the jet and the impingement surface. Also, the local Nusselt numbers are independent of the thermal boundary condition; i.e., the values are nearly the same for both isothermal and uniform heat flux conditions at the target surface. Finally, Nusselt numbers for a single equivalent jet viz. one with the same area as the five nozzles in the cluster combined, are compared for the case of the circular jet. |
