Abstract:Octagonal winglet vortex generators are installed on the traditional finned tubes to enhance heat transfer.The numerical simulation of the finned tube model with octagonal winglet is carried out by using FLUENT software,and the effect of the attack angles (10°,20°,30°,40°) of the octagonal winglet on the air-side flow and heat transfer of the finned tubes is studied at different Reynolds numbers(Re).The results show that the attack angle of the octagonal winglet has a significant effect on the heat transfer in the wake area behind the tube.Compared with the flat finned tube,the average Nusselt number (Nu) of the air side of the finned tube with octagonal winglet is increased by 13.1%~43.1% at different attack angles and Reynolds numbers,and the corresponding resistance coefficient (f) is increased by 6.9%~61.1%.By analysizing the PEC factor,the finned tube with the attack angle of 20° for the octagonal winglet has the best comprehensive heat transfer performance in the range of Reynolds number 862 to 3 735.