Critical Role of Ionic Properties on the Turbulence Drag Reduction Performance of Various Polyacrylamide Polymers in Liquid

Polymer-induced drag reduction flow has been widely investigated. However, the underlying mechanism of how the ionic properties of polymers affect their turbulence drag reduction performance remains unclear. This study reports an experimental investigation of the turbulent drag reduction performance of polyacrylamides (PAMs) with different ionic properties. The factors influencing the drag reduction performance of PAM solutions were explored, including flow time, concentration, turbulence intensity, and solution pH value. Meanwhile, the experimental results of turbulence drag reduction over a circular tube were verified against the classical Virk’s asymptote. It turned out that the experimentally obtained friction factors for the chosen PAM solutions of four ionic properties were close to the theoretical values and lie between the classical Newtonian turbulence and the Virk maximum drag reduction asymptote. The mechanism of turbulent drag reduction induced by PAMs with different ionic properties has been explored, and it turned out that the ionic properties of polymers play an important role in their drag reduction performance. In general, zwitterionic PAM shows the best turbulence drag reduction, anionic and nonionic PAMs are similar, and cationic PAM ranks last in terms of the effect of turbulence drag reduction. The increase of turbulence intensity and flow time will lead to the decrease of drag reduction effect; the increase of polymer solution concentration and pH value is beneficial to improve drag reduction rate.