Effects of longitudinal vortex generators on heat transfer and flow loss in turbulent channel flows

Abstract

The influences of four types of longitudinal vortex generators (delta wing, rectangular wing, delta winglet pair and rectangular winglet pair) on heat transfer and flow loss in turbulent channel flows are investigated in the present work. A numerical solver of the Navier-Stokes equations, based on the MAC algorithm, has been extended with the k-ɛ. turbulence model for this study. The results show that the longitudinal vortices produced by the vortex generators elevate significantly the level of turbulence kinetic energy in the flows and strongly disturb the thermal boundary layer. The mean heat transfer rate can be increased by 16–19% with the vortex generators for an area of channel wall which is 30 times larger than the vortex generator area. The ratio of heat transfer enhancement and flow loss increase indicates better performance for the rectangular winglet pair.