COMPARATIVE STUDY ON TURBULENT DRAG REDUCTION CHARACTERISTICS OF FLEXIBLE POLYMER AND RIGID POLYMER

The polymer turbulent drag reduction technology is widely applied to reduce the energy consumption of transportation, which performs various effects with the different polymers used. To study the similarities and differences of the turbulent drag reduction characteristics caused by polymers with different molecular chains, the flexible polymer (partially hydrolyzed polyacrylamide) and the rigid polymer (xanthan gum), we conducted research through use of a rheometer, circulation pipe, and particle image velocimeter. The rheological measurement results show that both polymer solutions exhibit shear thinning characteristics, and the degree of shear thinning increases with the increase of the concentration. The pressure drop measurement results show that the drag reduction effect of the two polymers increases with the increase of the solution concentration. According to the experimental data, xanthan gum performs better shear resistance than polyacrylamide solution and has a better drag reduction effect at low Reynolds number, but its maximum drag reduction rate is lower than that of polyacrylamide solution at high Reynolds number. The flow field measurement results of the particle image velocimeter show that the drag reduction mechanism of the two polymer solutions is similar. Both polymer solutions can effectively suppress the turbulence that causes the turbulent mean velocity profile to shift outward and reduce the intensity of normal velocity pulsation and Reynolds shear stress. The research results provide a good reference value for the application of polymer turbulence drag reduction technology.