A study on friction factor correlation considering the torsion effect in helical pipe flow

Abstract

A new correlation of friction factors in helical tubes for fully laminar flow was developed, covering curvature ratios from 0.05 to 0.15 and torsion parameters from 0.91 to 1.90. This correlation was separately analyzed the effects of curvature and torsion through regression analysis of experimental data and numerical results. The correlation was verified using experimental data and discussed on the influences of curvature ratio, torsion parameter, and Reynolds number. The friction factor decreased with a decrease in the curvature ratio and an increase the Reynolds number. At low Reynolds numbers, the friction factor decreased more rapidly compared to higher Reynolds numbers. It is confirmed that the friction factor formula for toroidal tubes was not applicable for torsion parameters exceed 1.0, especially in low Reynolds numbers flow. These findings highlight the importance of torsion effects, especially in large curvature coils, for accurate friction factor and pressure drop predictions.