Effects of tapered helical obstacles on heat transfer in tubes

Abstract In this computational investigation, the effects of helical tapering barriers on turbulent air flow through a horizontal circular tube with a constant surface heat flux were examined. The goal was to improve thermal performance and heat transfer. Multiple configurations were examined using the SST k - ϋ turbulence model in ANSYS Fluent 2023. These configurations included two helical tapering heights (2.5–5 mm, 2.5–7.5 mm) and helix ratios ( y = 2, 3, 4), with Reynolds numbers ranging from (10,000 to 60,000). At Re = 10,000, the configuration with a tapering height of 2.5–5 mm and y = 2 produced the greatest Nusselt number of 333, which is 151 % higher than the plain tube (Nu = 36). This was achieved due to the installation of helical barriers, which considerably boosted heat transport, nevertheless, in comparison to the plain tube, the friction factor increased by 82 % with this modification. Reducing the helix ratio or tapering height further enhanced both metrics, and increasing the Reynolds number increased the Nusselt number while decreasing the friction factor. All thermal performance factor (TPF) were greater than one, even with the higher flow resistance; the configuration that produced the most thermal enhancement had the highest TPF of 1.62. In particular, for low helix ratios and tapering heights, our results demonstrate that helical tapered obstacles are helpful in enhancing thermal performance.