نوع مقاله : پژوهشی اصیل
موضوعات
عنوان مقاله English
نویسندگان English
Transporting heavy crude oil through pipelines is a major challenge due to its high viscosity and the resulting significant pressure drop. Core-annular flow, in which a thin water layer separates the crude oil from the inner pipe wall, has been recognized as an effective method for reducing pressure loss. This study numerically investigates the effect of pipe inclination on the flow pattern of annular two-phase flow of water and non-Newtonian crude oil. The computational domain includes a pipe with an inner diameter of 40 mm and a length of 1.5 meters, where two phases are analyzed for inclination angles ranging from +90° (upward) to −90° (downward). Computational Fluid Dynamics (CFD) simulations were performed using ANSYS Fluent, and the Volume of Fluid (VOF) model was employed to capture the oil–water interface. The results indicate that core-annular flow can reduce the pressure drop by up to 85.5% compared to single-phase oil flow. As the pipe approaches a vertical orientation, the flow pattern transitions from semi-annular to fully annular and symmetric, which significantly reduces the likelihood of crude oil deposition on the pipe wall. In upward flow, increasing the inclination angle reduces the frictional pressure drop while increasing the gravitational component. Beyond 75°, the reduction in frictional component outweighs the gravitational increase, and the combined pressure drop is reduced from 1245 Pa at 75° to 1201 Pa at 90°. In downward flow, increasing inclination leads to higher frictional losses and lower gravitational contribution. For validation, the numerical results were compared with experimental data, and a maximum error of 7% was obtained
کلیدواژهها English
