Previous numerical simulations of polymer injectors often rely on fixed-viscosity models, which fail to accurately capture the severe shear degradation of non-Newtonian fluids under high-shear throttling conditions. To address this limitation and enhance polymer flooding efficiency, this study proposes an improved Carreau–Yasuda viscosity constitutive model to precisely simulate the flow behavior of polyacrylamide (HPAM) solutions. A comprehensive computational fluid dynamics (CFD) model was developed and validated, showing a viscosity prediction error of less than 8.6% across a wide shear rate range (0.1–10,000 s−1). Based on this dynamic rheological model, the internal flow channel of the injector was optimized, resulting in a novel spindle-type throttling unit. Simulation and field validation results demonstrate that the optimized structure achieves a significant pressure drop of 6.03 MPa at an injection flow rate of 96 m3/d—representing a 65% improvement over traditional designs—while successfully maintaining a viscosity retention rate above 85%. This research overcomes the traditional design conflict between high pressure reduction and viscosity preservation, providing an accurate numerical framework and practical guidance for engineering high-flow, robust-throttling polymer injectors.
Qian et al. (Tue,) studied this question.