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 .
Experimental verification of the four-sensor probe model for flow diagnosis in air water flow in vertical pipe
Measuring the volumetric flow rate of each of the flowing components is required to be monitored in production logging applications. Hence it is necessary to measure the flow rates of gas, oil and water in vertical and inclined oil wells. An increasing level of interest has been shown by the researchers in developing system for the flow rate measurement in multiphase flows. This paper describes the experimental methodology using a miniature, local four-sensor probe for the measurement of dispersed flow parameters in bubbly two-phase flow for spherical bubbles. To establish interdependent among different parameters corresponding to dispersed flow, the available model has been used to experimentally obtain different parameters such as volume fraction, velocity and bubble shape of the dispersed phase in the bubbly air-water flow.
Inhibition of Mild Steel Corrosion Using L-tryptophan and Synergistic Surfactant Additives
The corrosion inhibition characteristics of nitrogen containing amino acid L-tryptophan on mild steel in 0.1 M HCl solution, in the temperature range of 30-50 o C, was studied by weight loss and potentiodynamic polarization measurements. L-tryptophan significantly reduces the corrosion rates of mild steel; the maximum inhibition efficiency being 83% at 50 o C in presence of inhibitor concentration of 500 ppm. The effect of the addition of very small concentrations of anionic surfactant, sodium dodecyl sulfate (SDS), and of cationic surfactant, cetyl trimethyl ammonium bromide (CTAB), on the corrosion inhibition behavior of L-tryptophan was also studied. The inhibition efficiency (IE) of L-tryptophan significantly improved in presence of both surfactants. The effect of SDS and CTAB on the corrosion inhibition behavior of L-tryptophan appears to be synergistic in nature, the values of synergism parameter being greater than unity. The adsorption of inhibitors on mild steel surface obeyed Langmuir’s adsorption isotherm. The calculated thermodynamic parameters for adsorption reveal a strong interaction between the inhibitors and the mild steel surface. The results obtained by electrochemical studies are consistent with the results of the weight loss measurements. L-tryptophan acts more anodic than cathodic inhibitor.