Heat Transfer Characteristics by Impingement Jets Issuing from Dual Elongated Slot Nozzles.

Abstract

The effects of spacing between dual jets on the heat transfer characteristics and flow behaviors over the plate surface were investigated experimentally when the dual slot jets impinge on the target plate. The local heat transfer distributions were measured for various spacings at small nozzle-to-plate separation distances and the flow pattern also visualized by the oil-titanium IV oxide method. An infrared radiometer with a two-dimensional array of InSb sensor was employed to clarify space varying in the flow and heat transfer accompanying by the interferences between jets, and jet and spent flow. The characteristics of heat transfer, flow patterns and thermal distributions change with the spacing of the dual jets and the nozzle-to-plate separation. The phenomenon of axes switching, which is caused by the differences in the self-induced velocity in the non-circular vortices, was observed farther downstream compared with that of a single impingement jet. These phenomena consequently played an important role in the heat transfer enhancement.