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 Reference Bubble Velocity Vector for a Local 4 Sensor Probe Using Orthogonal High Speed Cameras
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, 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. The purpose of this research presented in this paper is to investigate the accuracy with which a 4-sensor probe can measure bubble velocity vectors using two orthogonal high speed cameras. 
 
 
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. A procedure was carried out whereby where all the readings are taken simultaneously from both the cameras and 4-sensor probe. The camera and DAQ setting are made such they were controlled by an external trigger signal that is achieved thought the same circuit that is been used for the probe signal. The velocity vector of the top plane, centre of gravity (COG) and bottom plane of the bubbles were measured using the high speed cameras and compared with the bubble velocity vector obtained from the probe signal. In this paper bubble velocity vector is quantified in term of a polar angle α an azimuthal angle β and a velocity magnitude.
Determination of Optimal Ball-Burnishing Parameters for Plastic Injection Moulding Steel
The objective of this study is to determine the optimal plane ball-burnishing parameters for plastic injection moulding steel PDS5 on a machining centre by utilising the Taguchi’s orthogonal array method. The design and manufacture of a burnishing tool are described. Four burnishing parameters, namely the ball material, burnishing speed, burnishing force and feed, were selected as the experimental factors in Taguchi’s design of experiments to determine the optimal burnishing parameters which have the dominant influence on surface roughness. The optimal burnishing parameters were found after carrying out the experiments specified by Taguchi’s L18 orthogonal table, by the analysis of variation, and by a full factorial experiment. The optimal plane burnishing parameters for the plastic injection moulding steel PDS5 were a combination of a tungsten carbide ball, a burnishing speed of 200 mm/min, a burnishing force of 300 N and a feed of 40 μm. The surface roughness Ra of the specimen can be improved from about 1 μm to 0.07 μm by using the optimal burnishing parameters for plane burnishing.