Investigation of oil-water flow in horizontal pipes using simultaneous two-line planar laser-induced fluorescence and particle velocimetry

Abstract

The flow of oil and water in pipes represents a challenging configuration in multiphase flows due to complex hydrodynamics which are still not fully understood. This can be observed in the large number of flow regimes encountered, which extend from smooth stratified flows to complex dispersions such as droplets of oil-in-water and water-in-oil. These flow configurations are the result of the inherent properties of the liquid phases, e.g., their densities and viscosities, interfacial tension and contact angle, as well as of flow conditions and related phenomena, such as turbulence, which have a direct effect on the interface instabilities giving rise to flow regime transitions. In this paper, experimental data are reported that were acquired at low water cuts and low mixture velocities using an aliphatic oil (Exxsol D140) and water as the test fluids in an 8.5 m long and 32 mm internal diameter horizontal pipe. A copper-vapour laser, emitting two narrow-band laser beams, and two high-speed cameras were used to obtain quantitative simultaneous information of the flow (specifically, spatiotemporally resolved fluid-phase and velocity information in both phases) based on simultaneous two-line Planar Laser-Induced Fluorescence (PLIF) and Particle Image and Tracking Velocimetry (PIV/PTV). To the best knowledge of the authors this is the first such instance of the application of this combined technique to these flows. It is found that the rms of the fluctuating velocity show peaks in high shear regions, i.e. at the pipe wall and interface.