Experimental Study of Fluid Flow and Heat Transfer in a Rectangular Channel with Novel Longitudinal Vortex Generators

A novel combined longitudinal vortex generator (LVG), comprising a rectangular wing mounted with an accessory rectangular wing, was presented and studied. Gas flow and heat transfer characteristics of this LVG in a rectangular channel were obtained experimentally and compared with those of the original rectangular LVGs under identical pressure gradient conditions. Results showed that a 45° orientation to the flow direction has optimal heat transfer characteristics for the original rectangular LVGs. In contrast, the combined LVGs, especially the upstream accessory wings, show higher heat transfer and lower gas flow resistance performances, with an optimal secondary orientation of 30°. For the combined LVGs, because the strong longitudinal vortices generated by the LVGs enhance the heat transfer between gas and channel walls, the temperature gradually increases from the centerline of the heater wall to the edge. The wall equivalent temperature with accessory wings is lower than that without accessory wings.