Experimental Analysis of Flow Characteristics and Annular Flow Boundaries of the Highly Viscous Oil/Water Lubricated Flow

Theoretical research on the characteristics of two-phase flow in horizontal pipelines is very important in the petroleum industry because a large amount of pumping power can be derived from the water-lubricated transportation of heavy or extraheavy crude oil. Experimental research of oil/water two-phase flow with water as the continuous phase in horizontal pipelines is carried out using tap water and two mineral oils with viscosity of approximately 0.743, 412, and 686 mPa.s, respectively. Two oil/water mixing devices of a water-ring generator and T-shaped three-way pipe arc adopted to compare the effect of oil/water annular flow. Pressure drop parameters, apparent viscosity, clear pictures, flow pattern maps, and resistance characteristics of oil/water two-phase flow are displayed in this article, together with comprehensive comments. Moreover, obtained results are compared with theoretical findings, experimental results, and empirical laws of different scholars in the literature. According to the ratio of fluid kinetic energy (inertial force) to potential energy (buoyancy), Froude number (Fr) is introduced to reach the state of hydrodynamic lift balance. Based only on experimental observations of the position of the layered/annular transition, a novel criterion is proposed to determine the regions with suitable operating conditions for application.