Authors: İsak KOTCİOĞLU, Teoman AYHAN, Hayati OLGUN, Betül AYHAN
Abstract: A detailed evaluation of performance parameters in the turbulent regime with regard to the enhancement of heat transfer using winglet-type vortex generators has been accomplished in this study. The heat transfer characteristics and flow structure in turbulent flow throught a rectangular channel containing built-in wing type vortex generator, have been investigated experimentally in the range of Reynolds number between 3,000 and 30,000. The geometrical configuration of interest is reminiscent of single element of a plate-fin cross-flow heat exchanger. The installation of wings is organized, in such a way that periodically interrupted enlarged and contracted channel flow domains can be established. Thus, each inglet pair acts as periodically interrupted divergent and convergent short channels in a rectangular channel. Wings were aligned at various angles of \beta=7-20° positively and negatively with the direction of main air flow direction. Each winglet pair induce longitudinal vorticity behind it, and strong mixing effects occur in a buffer region between divergent and convergent channel arrangements. The vortices in these flow domains cause enhanced heat transfer. It is observed that, the enhancement of heat transfer caused the increment of the friction coefficient.
Keywords: Heat Transfer Enhancement, Wing Type Vortex Generator, Periodically Interrpted Winglets, Divergent and Convergent Short Channels, Turbulent Flow
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