Flow Pattern Identification of Inclined Oil–Water Two-Phase Flow Using Generalized Magnitude and Sign Correlations

The oilwater two-phase flow in an inclined pipe exhibits fundamentally complicate behavior due to the effects of shear-induced turbulence and droplet-induced turbulence. As a result, internal waves with intermittent growth or attenuation are generated, and the resulting changes in flow pattern along the pipe diameter direction are difficult to accurately identify. We conducted oilwater two-phase flow experiment in an upward oil in water flow pipe (20 mm inner diameter and 3771 mm long) that was inclined at 45° to the vertical; then, the differential pressure sensors (DPSs), the eight mini-conductance probes signals, and the snapshots of the fluids taken by high-speed camera are collected in the test section of flow loop. We proposed an approach for analyzing the signals with generalized magnitude and sign correlations and extracting their scaling properties. We find that the scaling exponents from magnitude and sign series are sensitive to the flow pattern transition and can satisfactorily identify the four water-dominated, including dispersion of oil in water-countercurrent (D O/W CT), dispersion of oil in water-pseudo-slugs (D O/W PS), very fine dispersion of oil-in-water (VFD O/W), and dispersion of oil in water-cocurrent (D O/W CC). The study shows that the generalized magnitude and sign correlations can be a useful approach to analyze the nonlinear time series of complex multiphase flow systems.