Investigation on the effect of polymer in vertical oil-water two-phase flow using nonlinear analysis

This paper is devoted to investigating the effect of polymer on vertical oil-water two-phase flow using nonlinear analysis. For the comparison of flow characteristics in oil-water flows with different polymer dosages, an experiment in a vertical upward pipe with 20 mm inner diameter (ID) is conducted to obtain fluctuating signals of dispersed oil-in-water slug flow (D OS/W), dispersed oil-in-water flow (D O/W) and very fine dispersed oil-in-water flow (VFD O/W) using vertical multi-electrode conductance array sensor (VMEA). With the aid of recurrence plot, the effect of polymer on flow structure variation is qualitatively characterized. Then, recurrence quantification analysis and multi-scale weight complexity entropy causality plane (MS-WCECP) are respectively utilized to uncover the determinism and instability of the complex oil-water system with polymer addition. The results indicate that the recurrence plot can be effectively used to identify flow pattern and reveal the differences of flow structures in oil-water flows with and without polymer. The multi-scale weight complexity entropy causality plane can satisfactorily reflect the instability of polymer-added oil-water two-phase flow.