Use of a novel dual-sensor probe array and electrical resistance tomography for characterization of the mean and time-dependent properties of inclined, bubbly oil-in-water pipe flows

An array of dual-sensor conductance probes, which contains a number of dual-sensor probes
equispaced across the diameter of an 80 mm pipe, is introduced in this paper for characterizing
bubbly oil-in-water pipe flows inclined at angles from 15◦ to 60◦ to the vertical. Each
dual-sensor probe measures the local axial oil velocity and the local oil volume fraction at the
position of the probe. Choosing an averaging interval of 0.05 s, values of the local oil volume
fraction and the local oil velocity were measured simultaneously at the different probe
positions, enabling the time-dependent structure of the two-phase flow to be investigated.
After data processing, time-dependent variations of volume fraction along the pipe were found
which are consistent with the presence of intermittent Kelvin–Helmholtz wave structures in
the flow. A high-speed dual-plane ERT system was used to measure the axial propagation
speed of these Kelvin–Helmholtz waves, using cross correlation. This paper presents results
for the measured characteristics of inclined oil-in-water flows including (i) time-averaged and
time-dependent oil volume fraction and velocity distributions and (ii) the Kelvin–Helmholtz
wave properties including the wave speed, wave amplitude, wavelength and wave frequency.