Sensitivity analysis for a 4-sensor probe used for bubble velocity vector measurement
In recent years, there has been an increase in the level of interest shown in making flow rate 
measurements in multiphase flow. This in part has been brought about by the metering requirements 
of the oil and natural gas industries. Measuring the volumetric flow rate of each of the flowing 
components is often required and this is particularly true in production logging applications, where it 
may be necessary to measure the flow rates of oil and water down hole in vertical and inclined oil 
wells. Within the University of Huddersfield [1], work has been undertaken on the study of vertical and 
inclined multiphase flow. Previous work was based on the use of local, dual-sensor conductance 
probes to obtain the local axial velocity and volume fraction of the bubbles in multiphase flows [1]. The 
purpose of this research presented in this paper is to investigate the sensitivity of 4-sensor-probes, 
used for bubble velocity vector measurement to dimensional measurement errors of the probe and to 
errors in measuring the time intervals between the surfaces of the bubble contacting the sensors in the 
probe. 
 
 
The probe was manufactured from 0.3mm diameter stainless steel acupuncture needles due to their 
high level of rigidity. The acupuncture needles were mounted inside a stainless steel tube with an 
outer diameter of 4mm [2]. A procedure was carried out whereby an error on a specific probe 
dimension was introduced (errors in the range of -10 % to +10% of the true value of the dimension 
were used). The error in the measured bubble velocity vector was then investigated. A similar 
procedure was used to investigate the effect of measurement errors in the probe ‘time intervals’δt11 , 
22 δt and 33 δt on the measured bubble velocity vector. NB:The bubble velocity vector is quantified in 
terms of a polar angle α an azimuthal angle β and a velocity magnitude v . 
Results demonstrate that it is crucial to measure probe dimensions precisely (within the range of ±1%) 
as small errors in the probe dimensions or measured time intervals can give rise to large errors in the 
values ofα , β and v .
Measurement of bubble velocity components in a swirling gas–liquid pipe flow using a local four-sensor conductance probe
This paper presents a novel technique for measuring the local axial, radial and azimuthal velocity components of the gas in bubbly gas–liquid flows using a local four-sensor conductance probe. A mathematical model is presented showing how the velocity vector of a gas bubble can be calculated from seven time intervals taken from the output signals from each of the four conductance sensors located within the probe. The paper goes on to describe the construction of a local four-sensor probe and the associated electronic measurement circuitry. Results are presented showing the distributions of the mean local axial, radial and azimuthal gas velocity components in vertical, bubbly gas–liquid flows, both with and without swirl. These results were obtained using the four-sensor probe in a vertical 80 mm diameter pipe into which a swirl generator could be installed. Additional results are presented showing the local gas volume fraction distribution, also obtained from the probe, in bubbly gas–liquid flows with and without swirl. It was found, as expected, that the presence of swirl caused a significant increase in the magnitude of the measured azimuthal velocity of the gas, particularly at the pipe walls. It was also found that, at a comparatively high water flow rate, the presence of swirl caused the gas bubbles to preferentially accumulate at the centre of the pipe.
A dual optical probe for volume fraction, drop velocity and drop size measurements in liquid-liquid two-phase flow
This paper describes the development and application of a dual optical probe for local volume fraction, drop velocity and drop size measurements in a kerosene-water liquid-liquid two-phase flow. A sampling tube procedure and interface tests were used to calibrate the leading optical sensor and both optical sensors for measurements of the local volume fraction and drop velocity as described in this paper. Measurements were carried out in a large-scale vertical two-phase facility mainly at the pipe centre-line to demonstrate the advantages of using optical fibres with normal cut ends in a kerosene-water two-phase flow. Finally the applicability of this probe for measurements in gas-liquid two-phase flows and gas-kerosene-water three-phase flows has also been demonstrated.