Drag reduction of a special micellar drag reducer and its rheological characteristics

To develop more economical technology for pipeline water transport and to delve deeper into the drag reduction mechanism of micellar drag reducers, experiments have been conducted to examine the pipe flow drag reduction and rheological properties of dilute aqueous solutions of oleyl dihydroxyethyl methyl ammonium chloride （Ethoquad O/12）, with sodium salicylate （NaSal） as the counterion additive. Drag reduction tests indicate that the maximum drag reduction rate can reach an order of magnitude of 70%. The shear resistance and anti-aging capability all increase as the molar ratio of the counterion to the drag reducer, a characteristic distinct from that of other cationic micellar drag reducers. Shear viscosity measurements reveal that the dilute aqueous solutions of Ethoquad O/12, which exhibit drag reduction effects, are highly complex non-Newtonian fluids. Moreover, as the molar ratio increases, the shear rate at which the micellar structure begins to form networks also increases. Shear stress relaxation experiments confirm that the micellar aggregate structure, characterized by a relaxation time on the order of 0.1 seconds, is indispensable for the drag reduction effect of this micellar drag reducer. A low molar ratio imparts strong viscoelasticity to the drag-reducing fluid, whereas a high molar ratio weakens its viscoelasticity. The elucidation of this unique drag reduction characteristic provides valuable technical support for the development of pipeline water transport technology, and the corresponding viscoelastic properties offer a new reference criterion for exploring the drag reduction mechanism of additives.