Mechanical degradation of polyalphaolefin in turbulent drag reduction flow in rheometer and pipeline

Abstract

Turbulent drag can be reduced by the use of anti-turbulent additives, which are often associated with significant economic benefits. For half a century turbulent drag reduction has become a hot research topic. However, under the strong hydrodynamic force of turbulent flow, chains of the polymer’s macromolecules may undergo significant mechanical degradation. In the present work, we investigated drag reduction and mechanical degradation characteristics of oil-soluble polymer-polyalphaolefin (PAO) in turbulent flows in a parallel-plate disk rheometer, cylindric rotational rheometer, and commercial oil pipeline. The influence of Reynolds number, temperature, polyalphaolefin composition, and concentration on polymer mechanical degradation have been analyzed. We revealed different degradation behaviors in turbulent flows for oil-soluble polymers in rheometer and pipeline. A degradation law for oil-soluble polymers in a rheometer and a general model of degradation in the pipeline have been derived, which can be used to predict drag reduction efficiency DR and effective polymer concentration θ in rheometer and commercial pipelines. The models are in high agreement with experimental results.