Paper Title
Thermo-Hydraulic Performance Improvement of a Channel Flow Embedded with Winglet Vortex Generators

Abstract
The turbulent forced convective heat transfer behaviors in a channel flow inserted with winglet vortex generator (WVG) have been numerically investigated. The WVG are attached to one wall while the bottom wall of the duct is insulated. The side walls of the duct are imposed with symmetry boundary condition.The influence of flow angle of attack (α) from 30o to 90o, Reynolds number (Re) from 3500 to 20,000, and the winglet arrangements on heat transfer and fluid flow are presented. The WVG are used to produce streamwise and transverse vortices on the top of the main flow to enhance the convective heat transfer. The vortex flow by WVG can help to thin the thermal boundary layer thickness and provide more uniform fluid mixing leading to drastic increase in the heat transfer rate over the duct. The maximum thermal performance is found to be 2.2 for the WVG with the common flow down arrangement at α =30o, Re= 3500. Whereas the maximum Nusselt number ratio is about 4.4 at lower Re for α =30o. Keywords - Solar Air Heater, WVG, Turbulent Flow, Nusselt Number, Friction Factor.