Modification of the Velocity Profiles of Turbulent Flow of Water Using Polymeric Solutions; Experimental Investigation

Low concentration of drag reducing agents have found their efficient applications to reduce required energy of the pipeline turbulent flow transportation. These additives can effect on turbulent structures, and can modify velocity profile, and thus they cause to reduction of the skin friction of the flow. In the present study, two commercially available copolymer of polyacrylamide with different molecular weights, were employed to study the possible impact of different concentrations of the polymers on pressure drop reduction of turbulent flow of water in pipeline. The obtained results demonstrated that both the copolymer showed high drag reduction along with low degradation rate for 2hr of the
experimentation. Addition of 30ppm of the high molecular weight polymer to turbulent flow showed 54% drag reduction. Following the drag reduction measurement, turbulent velocity profiles for the optimum concentration of the two polymers were obtained by using laser Doppler velocimetry technique. The results showed a tendency to laminarization of the flow supported with low amounts of Reynold stresses and velocity fluctuations in the presence of the polymer. In all the cases, the effects of the higher molecular weight polymer on the velocity profiles of the turbulent flow is more desirable than lower molecular weight one.