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 vectors in bubbly air water multiphase flow
Measurement of the volumetric flow rate of each of the flowing components in multiphase flow is often required and this is particularly true in Production Logging applications. Thus, an increasing level of interest has been shown in making flow rate measurements in multiphase flow. A new generation of tomographic instrument, which enables measurement of the instantaneous local velocity vector and the instantaneous local volume fraction of the dispersed phase, is now being introduced. However validation and calibration of such instruments is necessary. 
 
 
This thesis describes the development of a miniaturised local four-sensor conductivity 
probe capable of acquiring measurements of the local velocity vector, gas volume fraction and the local axial gas velocity in the bubbly gas-liquid flows. Experimental techniques in which the probe was used to obtain the local gas velocity vector and the local gas volume fraction in a bubbly gas-liquid flow are also described. 
 
 
High speed cameras are introduced for the measurement of the reference velocity of the bubbles. The camera images are also used to plot the trajectory of any bubble that hits all four-sensor of the probe. 
 
 
Extensive experimental results showing the distribution of the local gas volume fraction and the local axial, azimuthal and the radial bubble velocity components in vertical and swirling gas-liquid flows are presented.
Joint strength of aluminum ultrasonic soldered under liquidus temperature of Sn–Zn hypereutectic solder
Abstract In order to obtain high-strength aluminum joints, ultrasonic soldering of 1070 aluminum was conducted under liquidus temperature of Sn–Zn hypereutectic solder. A device for ultrasonic soldering was assembled, which propagated ultrasonic vibrations in a direction perpendicular to joining surfaces. This device joined 1070-Al using quasi-melting Sn–Zn hypereutectic solder without using any artificial spacers. The strength of the solder joints was evaluated by tensile tests. The optimum joining conditions were determined, and the effects of solder compositions and soldering temperature on the joint strength and the solder layer thickness were examined. In this ultrasonic soldering process, the highest tensile strength was obtained for the solder joints fabricated at 220 °C for the Sn–23Zn and Sn–40Zn solder compositions. The joint strength was equivalent to that of 1070-Al heat treated at 220 °C. The sound joints were obtained at 300 °C using Sn–82Zn solder, the liquid phase volume fraction of which was theoretically only 0.24. The present work also revealed that the thickness of retained solder layer in the joint after ultrasonic soldering could be estimated. Accordingly, ultrasonic soldering under the liquidus temperature of Sn–Zn hypereutectic solder could be a spacer-free soldering method to obtain high-strength aluminum joints.