Numerical investigations on heat transfer characteristics of curved rectangular winglet placed in a channel

Abstract

Flow and heat transfer characteristics of curved rectangular winglet vortex generators (RWVGs) are investigated numerically. Three-dimensional numerical computations have been carried out for flow through a channel with curved RWVG mounted on its bottom wall. Effect of curvature of RWVG having concave and convex shapes with respect to the flow facing surface, has been addressed in terms of arc angle which is varied in the range from 15° to 120° for fixed arc length. Effect of curvature in concave and convex RWVG on flow and heat transfer characteristics has been compared with that of plane RWVG. Temperature and flow field characteristics near the plate surface have been presented and discussed with the help of temperature contours and streamline plots. Enhancement in heat transfer and pressure loss are examined by using Nusselt number and friction factor respectively. Maximum enhancement in heat transfer is found to be 22% for concave shape RWVG having arc angle equal to 75° as compared to channel in absence of RWVGs. The mechanism of heat transfer enhancement is explored with the help of secondary flow intensity and field synergy principle. Thermodynamic performance of various RWVGs has been analysed by calculating entropy generation rate caused by heat transfer and friction. Finally, overall thermo-hydraulic performance of various curved RWVGs has been reported and compared with that of plane RWVG.