Experimental study on drag reduction performance of mixed polymer and surfactant solutions

Abstract

In this work, the mixed aqueous solutions of cationic surfactant – cetyltrimethyl ammonium chloride and non-ionic molecular polymer – polyacrylamide were tested to verify the speculation about their intensification possibilities of drag reduction performance. Sodium salicylate (NaSal) was used as the counter-ion salt. Six different combinations of mixed solution concentrations were tested at different temperatures ranging from 25°C to 50°C. Pure surfactant and polymer solutions were tested as control couples. It was found that the curves of mixed solutions could be divided into enhanced drag reduction zone, stable drag reduction zone and destroyed drag reduction zone. Surfactant molecules form micelles round polymer chains. Then the two additives form a kind of reinforced concrete structures, which were more complex and more effective in restrain vortices, leading to the intensification of drag reduction in enhanced zone and stable zone compared to pure surfactant solutions at low temperatures. The addition of polymers also increased drag reduction efficiency in destroyed zone by providing a wider range of Reynolds numbers. In addition, the results indicated that temperatures were more influential than concentrations, raising the temperature to change the structures of solution is more effective than increasing the quantity of structures.