A numerical investigation on single-phase flow characteristics and frictional pressure drop in helical pipes

Helical pipes have been widely applied in a vast range of industries owing to the remarkable characteristics. In practice, they still face the challenge of undesirable increased pressure resistance. The investigation on the flow characteristics in helix is essential to explore the pressure loss mechanism. In this paper, thek - omega model andk - omega SST model are utilized to investigate the flow characteristics in helical pipes with varying Reynolds number and geometry parameters including coil radius, pipe diameter and coil pitch. The influence of each variable on the flow field, especially axial and secondary velocity distribution, is thoroughly examined. The relationship between Darcy friction factor and different dimensionless variables is analyzed, which turns out to be positively dependent on radius ratio and inversely dependent on Reynolds number. The available correlations of friction factor in the laminar and turbulent regime in literature are presented and the prevailing forms are summarized, some in good accordance with simulation. Based on the results, new correlations are proposed and the coefficients are determined by virtue of non-linear data fitting, which could provide assistance for the design and optimization of helical pipes.