Velocity and turbulence measurements of oil-water flow in horizontal and slightly inclined pipes using PIV

Abstract

Oil-water flows in horizontal and slightly inclined pipes are investigated using Particle Image Velocimetry (PIV). PIV offers a powerful non-invasive tool to study such flow fields. The experiments are conducted in a 15 m long, 56 mm diameter, inclinable steel pipe using Exxsol D60 oil (viscosity 1.64 mPa s, density 790 kg/m3) and water (viscosity 1.0 mPa s, density 996 kg/m3) as test fluids. The test pipe inclination is changed in the range from 5° upward to 5° downward. The experiments are performed at mixture velocity 0.25 m/s and inlet water volume fraction 0.25. The instantaneous local velocities are measured using PIV, and based on the instantaneous local velocities mean velocities and turbulence profiles (U-rms, V-rms and Reynolds stresses) are calculated. The time averaged cross sectional distributions of oil and water phases are measured with a traversable gamma densitometer. The flow regimes are determined based on visual observations. The measured flow regimes, water hold-up, slip ratio and velocity and turbulence profiles show a strong dependency with pipe inclination.