Thermo-hydraulic performance of round tubes installed with double V-shaped winglet vortex generators: Effect of blockage ratio

Abstract

Double V-shaped winglet vortex generators is proposed in the present research enhancing heat transfer and thermal-hydraulic performance factor. The numerical simulation was performed to study the effects of blockage ratios (e/D = 0.05-0.15) and Reynolds numbers (Re = 5000-15,000) on heat transfer rate, flow structure, local heat transfer, pressure loss and thermal-hydraulic performance factor characteristics. The double V-shaped winglets were installed in tandem arrangement on the top and bottom of tubes with constant pitch ratio of p/D = 1.0. Water was employed as the working fluid for Reynolds numbers ranging from 5000 to 15,000 under constant wall temperature boundary conditions. The numerical results demonstrated that the vortex generators induced swirling motion which helped in improving fluid flow mixing, leading to heat transfer enhancement with a moderate pressure loss penalty. Heat transfer and friction loss increased with increasing blockage ratio and Reynolds number while thermal-hydraulic performance factor showed opposite trend. The maximum thermal-hydraulic performance factor of 1.89 was obtained by using the vortex generator with the smallest blockage ratio (e/D) of 0.05 at the lowest Reynolds number of 5000.