Distortion of Velocity Profiles of Water Flow with Heavy Molecular Weight Polymers

Abstract

Transportation of fluids in pipelines is common in many industrial processes. The energy requirements for this transport is high because of the need to overcome the occurring frictional pressure drop or drag. However, the addition of high molecular weight polymers to fluid flows has been known to cause a reduction in the frictional pressure drop. It has also been reported to cause other changes in the flow including changes in the turbulence characteristics, holdup as well as asymmetry of the velocity profiles. In this work some experimental results are presented in order to gain better insight into the deviations from axisymmetry of velocity profiles of water flow in pipes when drag reducing agents are added. Drag reduction studies were carried out in a horizontal 14mmID acrylic pipe with hydrolyzed polyacrylamide and different molecular weights polyethylene oxide used as additives in fully developed flows. Asymmetry was observed at both transitional and turbulent flow regimes for all tested polymer types and it increased with molecular weights. While the molecular weight and degree of formation of entanglements and aggregates of the polymer fibers are indicated as the causes of the observed profile asymmetry, the contribution of system/setup imperfections can be ruled out.