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

• Use of large arrays of dual-sensor and four-sensor probes.
• Measurement of local velocity components in inclined oil-in-water flows.
• Measurements enable visualisation of Kelvin–Helmholtz wave structures.
• Standard deviations of flow components measured using different sampling periods.

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 153 mm diameter pipe. The flow properties that were measured were (i) the local in-situ oil volume fraction αα; (ii) the local oil velocity uouo in the axial direction of the pipe (the ZZ direction); and (iii) the local oil velocity uYuY in the direction from the lower side of the inclined pipe to its upper side (the YY direction). Oil velocities in the XX direction (orthogonal to the YY and ZZ directions) were found to be negligible. For all of the flow conditions investigated it was found that the mean value of αα 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 αα with distance in the −Y−Y direction became greater as the pipe inclination angle θθ from the vertical was increased. It was also found that the mean value of uouo 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−Y direction again becoming greater as θθ was increased. For θ=o45θ=45o, a water volumetric flow rate Qw=16.38m3h−1, an oil volumetric flow rate Qo=6.0m3h−1 and using a sampling period T=0.05s over a total time interval of 60s, it was found that at the upper side of the inclined pipe the standard deviation in uouo was 31.6% of the mean value of uouo. Furthermore for T=0.05s, θ=o30θ=30o, Qw=16.38m3h−1 and Qo=6.0m3h−1 it was found that the standard deviation in the cross-pipe oil velocity component uYuY was approximately equal to the standard deviation in the axial velocity component uouo. 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 TT will be of considerable value in validating mathematical models of time dependent oil–water 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.