Large probe arrays for measuring mean and time dependent local oil volume fraction and local oil velocity component distributions in inclined oil-in-water flows

Abstract

Arrays of dual-sensor and four-sensor needle conductance probes have been used to measure the mean and time dependent local properties of upward inclined, bubbly oil-in-water flows (also known as dispersed oil-in-water flows) in a 153mm diameter pipe. The flow properties that were measured were (i) the local in-situ oil volume fraction α ; (ii) the local oil velocity o u in the axial direction of the pipe (the Z direction); and (iii) the local oil velocity Y u in the direction from the lower side of the inclined pipe to its upper side (the Y direction). Oil velocities in the X direction (orthogonal to the Y and Z directions) were found to be negligible. For all of the flow conditions investigated it was found that the mean value of α varied from a maximum value at the upper side of the inclined pipe to a minimum value at the lower side, and that the rate of decrease of this mean value of α with distance in the Y − direction became greater as the pipe inclination angle θ from the vertical was increased. It was also found that the mean value of o u was greatest at the upper side of the inclined pipe and decreased towards the lower side of the inclined pipe, the rate of decrease with distance in the Y − direction again becoming greater as θ was increased. it was found that the standard deviation in the cross-pipe oil velocity component Y u was approximately equal to the standard deviation in the axial velocity component o u . These large temporal variations in the local flow properties have been attributed to the presence of large scale Kelvin-Helmholtz waves which intermittently appear in the flow. It is believed that the techniques outlined in this paper for measuring the standard deviation of local flow properties as a function of the sampling period T will be of considerable value in validating mathematical models of time dependent oilwater flows. It should be noted that the principal focus of this paper is on the measurement techniques that were used and the methods of data analysis rather than the presentation of exhaustive experimental results at numerous different flow conditions.

Oil droplet sizing and velocity determination using a fiber-optic reflectometer

“…Compared to the literature on air bubble sizing and velocity determination using conductivity or optical-fiber probes, the number of studies on oil droplet sizing and velocity determination in oil-water mixture flows is relatively limited. Among some valuable works [30][31][32][33] employed dual conductivity probes to measure the velocity, volumetric fraction, and size distribution of oil droplets. Using a single cleaved optical-fiber probe [34], first demonstrated the possibility of measuring oil-phase residence time in a vertical kerosene-water mixture flow.…”

Imaging water velocity and volume fraction distributions in water continuous multiphase flows using inductive flow tomography and electrical resistance tomography

“…For RT#2, however, which assumes that the zero'th order velocity component can be replaced by an axisymmetric distribution of the form given in equation ( 9), the maximum water velocity occurs at some distance below the upper side of the inclined pipe, but above the mid-point of the flow cross section (figures 11(b)-14(b)). One of the authors of the current paper has made a number of exper imental studies of the velocity distributions of the dispersed phases (oil & gas) in upward inclined, water continuous multiphase flows [18][19][20] and has shown that the axial velocity of the dispersed phase is always a maximum at the uppermost side of the inclined pipe. It seems unlikely that this form of velocity distribution should not also apply to the continuous water phase-and hence, for inclined multiphase flows, the water velocity profiles reconstructed using RT#1 are perhaps more representative of the true water velocity profiles than those reconstructed using RT#2.…”

Time Irreversibility from Time Series for Analyzing Oil-in-Water Flow Transition

“…In addition, more advanced experimental methods are adopted to explore the oil bubble characteristics. The methods such as miniprobe detection [8], high speed photography [9], microwave measurement [10], process tomography [11], and PIV technology [12] have been applied to study the characteristics of oil-in-water two-phase flow.…”