Design and numerical simulation of a Venturi-swirl coupled mixer for weighted drilling fluid

To address the need for the rapid preparation of weighted drilling fluids with different densities to ensure drilling safety during oil and gas exploitation, a novel weighting device coupling a Venturi tube with a swirl mixer equipped with static anti-agglomeration blades is developed. Computational fluid dynamics simulations are performed using the Mixture multiphase flow model, and the coefficient of variation and inlet-to-outlet pressure difference are employed as performance indicators to comparatively evaluate the effects of structural and operating parameters on mixing performance. The results indicate that a blade height of 25 mm, two blades, and a swirl mixer diameter of 400 mm constitute the recommended combination of structural parameters. Under this configuration, the COV at the outlet cross-section is 0.0059, while the inlet-to-outlet pressure difference is 0.2021 MPa. Compared with the original configuration, the COV decreases from 0.0160 to 0.0059. Within the investigated ranges of target drilling-fluid density and barite powder flow rate, the outlet COV of the recommended configuration remains approximately 0.006, indicating stable mixing uniformity over the specified operating range. These results provide a numerical basis for the structural optimization and subsequent prototype validation of the Venturi–swirl coupled mixer for weighted drilling fluids.