Research on Turbulent Drag Reduction of Surfactant-Polymer Mixed Solution Using Flow Visualization Technique

Objective: To explore the drag reduction effect of surfactant-polymer composite system in turbulent flow. Methods: the turbulent drag reduction experiment of the one-component solution and the composite solution was carried out in a rectangular pipeline platform, respectively. Moreover, the particle image velocimetry (PIV) was utilized to measure the turbulent flow field of the drag-reducing flow. Results: Experimental results show that the composite drag reduction system has a drag reduction gain effect in comparison with the one-component surfactant or polymer solution. Especially in the destroyed drag reduction zone, the composite drag reduction system has the strong shear resistance. When polyacrylamide (PAM) is added, the Reynolds drag reduction range of cetyltrimethyl ammonium chloride (CTAC) solution is broadened and the drag reduction gain efficiency reaches 46%, which will provide favorable conditions for oil transportation and other industries. Conclusion: Compared with one-component CTAC solution, the mean velocity distribution of composite solution moves up in the logarithmic-law layer, the velocity fluctuation peaks of the streamwise direction shift away from inner wall of pipe, and the inhibition degree of the normal velocity fluctuation increases with the augment of PAM concentration. In contrast with water, the Reynolds shear stress of one-component CTAC solution and composite solution are reduced significantly, and the vortex structures in the region near the wall are suppressed dramatically with the decrease of vorticity intensity.