Browsing by Author "Sanderson, M. L."
Now showing 1 - 19 of 19
Results Per Page
Sort Options
Item Open Access The applications of ultrasonic imaging and signal processing in two-phase flow measurement(Cranfield University, 1996-08) Chen, Z.; Sanderson, M. L.The applications of ultrasonic imaging and signal processing in two-phase flow measurement have been investigated in this thesis. The scattering by single and many scatterers was studied experimentally and numerically. The statistical properties of the scattered waves from many scatterers were examined and the corresponding results are presented. Ultrasonic transmission/reflection mode tomography was introduced. The theories of reflection mode computerised tomography were developed, by which reflectivity functions and scattering amplitude functions can be reconstructed. Image restoration and interpretation methods are presented. Computer simulation of ultrasonic measurements were carried out. A ultrasonic tomographic imaging system was developed, in which fan-shaped sound beam insonification was employed. Static physical models were used to simulate two-phase flows. In order to speed up the data acquisition of a tomographic imaging system, the single receiver mode and multiple receiver mode data acquisition arrangements were studied by experiments. Experiments on imaging small and large objects were carried out. Several signal and image processing methods were examined. A modified histogram equalisation algorithm was developed for processing the resultant ultrasonic images. The experiment results show that the proposed image reconstruction methods are satisfactory. Possible future developments are proposed.Item Open Access Blending of viscous Newtonian and pseudo-plastic fluids(Cranfield University, 1992-04) Grenville, R. K.; Sanderson, M. L.Blend times and power consumption have been measured for Newtonian and pseudo- plastic fluids in agitated, baffled vessels with diameters of 0.30,0.61 and 1.83 m. The viscosities of the fluids were selected to give a range of Reynolds numbers between 200 and 105. Four impellers were tested with diameters between T/3 and T/2 positioned at T/3 clearance above the lowest point of the vessel base. The impellers were typical of those found in the chemical industry.Item Open Access The Development and Modelling of a Novel Clamp-on Ultrasonic-Thermal and Ultrasonic Multiple Reflection Flowmeter for Liquid Applications.(Cranfield University, 1994-02) Law, Masa; Sanderson, M. L.; Guilbert, A. R.; Ward, G.The development of a novel combined "ultrasonic/thermal" with "ultrasonic multiple reflections" clamp-on meter for measuring a wide flowrate range of clean liquids in small diameter pipes is presented. Current existing flowmeters based on ultrasound cannot measure very low flowrates for single phase liquids. The ultrasonic/thermal technique can measure single phase flows in the range 0 to 0.6 m s' in pipes with diameters as small as 15 mm. It can also detect and measure reverse flows. The minimum flowrate for the ultrasonic multiple reflection technique is about 0.55 m s', and theoretically, the measurement accuracy increases with increased flow velocity. The ultrasonic/thermal technique is based on a heating element and transducer pair(s) which can be clamped to the outside of a pipe. With the heaters switched on, the changes in the temperature of the pipe and the liquid inside it result in changes in transit time. The flowrate can be therefore estimated by either the transit time difference across the pipe at the two symmetric locations with respect to the heater centre, or at one location with a heater off/on comparison. The latter approach was felt to be the promising for low flowrate measurements and therefore selected for the numerical and the experimental investigations. The multiple reflection technique was developed based on the conventional transit time flowmeter. This technique extended the measuring range of the flowmeter and provided cross calibration for the ultrasonic/thermal technique. A computer model was developed for the ultrasonic multiple reflection technique. However, there was insufficient experimental data to confirm the computer prediction. Results from computational fluid dynamics (CFD) analysis of the meter are presented. For vertical pipes an axisymmetric model was used, but the presence of buoyancy forces required the use of a 3-D model for horizontal pipes. Temperature and velocity distributions and ultrasonic transit times have been computed and are presented. In order to overcome the problem of mode conversion and refraction at the pipe wall/transducer mounting interface, novel transducers and mounting blocks are presented. A prototype heater and ultrasonic transducer system together with electronics for signal generation and transit time measurement have been designed and constructed. A hydraulic system has also been designed and constructed for testing the developed clamp-on flowmeter. Experimental results from this apparatus are presented and compared with the CFD predictions, and a technique for compensating for variations in inlet temperature is described. The full scale difference between the computed values and experimental results of the meter for low flowrate measurement was about 3.5%.Item Open Access Development of baseline stability in an electromagnetic flowmeter for dielectric liquids(Cranfield University, 1998-10) Durcan, L. P.; Hemp, J.; Sanderson, M. L.This thesis is concerned with the development of a prototype electromagnetic flowmeter for dielectric liquids. A initial prototype flowmeter is tested in laboratory conditions with a liquid of low conductivity, the conclusion of these initial tests being that the stability of the flowmeter is below that required for its design applications. This lack of stability is a problem reported on several occasions in similar projects involving electromagnetic flowmeters for dielectric liquids. Therefore the main body of the work is spent investigating the causes of instability and trying to redress the necessary problems in order that a viable working prototype is developed. Problems of thermal instability, electrostatic and electromagnetic shielding are addressed along with the causes and effects of all the major noise and unwanted signals experienced in such a system. A new prototype is developed incorporating stability driven improvements. This new design is rigorously tested and assessed. The stability of the meter is considered with respect to its flow related output. Several parameters of operational stability are given in the examples considered. A final assessment is then made of the flowmeters baseline performance and a account of any remaining instability is given with respect to the issue developed throughout the thesis. The conclusions indicate that the electromagnetic flowmeter for dielectric fluids does produce a linear output based on Faraday's law of induction. They also indicate that the instability experienced previously can be broken into its constituent parts and each contributor accounted for and reduced, working towards the ideal totally stable flowmeter.Item Open Access Electromagnetic flowmeter for dielectric liquids.(Cranfield University, 1995-07) Amare, T.; Sanderson, M. L.; Hemp, J.Experimental investigation and theoretical analysis of an electromagnetic flowmeter designed for use with dielectric liquids has been carried out. An extensive survey of the industrial users of flowmeters has been made, involving the participation of over 47 companies, which provides information about the current industrial use, attitudes and attributes of electromagnetic and other types of flowmeters. The design of the flowmeter is mainly concerned with overcoming the charge noise that is associated with the flow of dielectric liquids so as to effectively detect the weak flow signal. It is shown that the working of the flowmeter depends heavily on the design of the eddy current free electrostatic shield. The result of the mathematical analysis of the design is a simplified formula for predicting the sensitivity of the meter. It is adjusted to take account of such factors as end-effects and electrical properties of the flow conduit of the meter. Experimental results show that not only an induction flowmeter based on Faraday's principle is possible but also the measured values of the flow signal closely matches those obtained from the formula. It is suggested that the formula can be generalised to include moderately conducting liquids which is supported by results achieved from experiments on water. Finally, recommendations for future work are put forward for further improvement of the design.Item Open Access Electromagnetic flowmeters in multiphase flows(Cranfield University, 1993-09) Krafft, Rainer; Sanderson, M. L.; Hemp, J.The response of an Electromagnetic Flowmeter to a secondary, nonconducting phase in a continuous conducting phase is investigated. Experiments are carried out on a commercial 2" Foxboro flowmeter with sinusoidal mains field excitation and point electrodes. The main aspects which are looked for are the change in flow signal and transformer signal. A mathematical model is developed to simulate the effect of the nonconducting phase in. the form of single spherical particles. The model also allows one to alter the electrode geometry. A second flowmeter is designed to incorporate an improved electrode and coil geometry as well as a newly designed signal processing unit. In a series of experiments, the predictions of the theoretical model have been mostly verified.Item Open Access Electromagnetic measurement of bubble velocity in two-phase dielectric fluid flow(Cranfield University, 1997-10) Donhauser, Norbert; Sanderson, M. L.This thesis deals with the theoretical and experimental investigation of two-phase flow for a dielectric liquid electromagneticf lowmeter. So far only limited investigationsi nto the possibleu se of electromagneticf lowmeters for multiphasef low measuremenht ave been made. These have been restricted to electromagnetic flowmeters designed for conducting water based (electrolytic) fluids. The possibility of designing electromagnetic flowmeters for use with insulating (dielectric) fluids such as oil and petrol has been existed for some years. However the measuremenot f two-phase flow of insulating fluids using electromagnetic flowmeters and the application of this knowledge to the measurement of the separate phases has not yet been a subject for research. An analytical model is developed which evaluates a transformer signal that is produced on the electrodes when a bubble unbalances eddy currents while it passes through the meter. The shape and magnitude of this signal for various positions in the pipe cross-section is investigated. The behaviour of this transformer signal for various electrode shapes is studied as well and it is found that when using large area electrodes the position of the amplitude along the pipe axis remains almost constant. For measuring the speed of bubbles passing through the meter a frequency analysis is carried out and shows that the peak frequency of the signal is proportional to the velocity of the bubbles. A flowmeter is built to carry out experimental work. The first sets of experiments are carried out with plastic beads fixed on a thin string which is attached around two wheels. The speed of the beads is adjusted by an electromotor which powered one wheel. In a second experimental design gas bubbles are injected in a vertical pipe which is filled with dielectric oil. Both types of experiments exhibit the behaviour predicted in theoretical analysis.Item Open Access Fluid flow and heat transfer around mechanical seals(1990-09) Barnes, N. D.; Sanderson, M. L.Mechanical seals are used extensively on rotary applications where the sealed fluid is under pressure. They may rightly be considered to be generally reliable and trouble free, many giving lives of over 3 years. However, a significant number, particularly on arduous and often critical duties, exhibit apparently random mid-life failure characteristics which cannot be easily explained. Of these "random" failures, the largest proportion appear to be attributable to overheating due to loss of the vital interface fluid film. The mechanism of interface film loss depends on a large number of interrelated variables and a substantial amount of work has been carried out over many years to attempt to alleviate the problem. Little work however has been reported on the nature of the fluid flow around the seal; this is determined by seal chamber geometry and affects the removal of potentially deleterious heat, vapour or gases, and solids. At present, many seals are required to run in "stuffing boxes" - cavities designed for soft packing rather than mechanical seals. The aim of this project has been to study the flow behaviour in these stuffing boxes and a number of novel chamber designs. The techniques involved using transparent housings and direct measurements of convective heat transfer coefficients. Significant improvements over existing designs were achieved using a housing flared at 45° away from the seal and this design forms the basis of recommendations for improved seal systems. This design was tested under simulated field conditions described in a Design Study and Case Study and found to be successful. The recommendations are backed up by a mathematical model of turbulence viscosity which seeks to explain some of the complex structured flows observed. A corollary to the thesis explains how the results of this work will form a major input to improved international standards.Item Open Access Fluid flow and heat transfer around mechanical seals.(1990) Barnes, N. D.; Sanderson, M. L.Mechanical seals are used extensively on rotary applications where the sealed fluid is under pressure. They may rightly be considered to be generally reliable and trouble free, many giving lives of over 3 years. However, a significant number, particularly on arduous and often critical duties, exhibit apparently random mid-life failure characteristics which cannot be easily explained. Of these "random" failures, the largest proportion appear to be attributable to overheating due to loss of the vital interface fluid film. The mechanism of interface film loss depends on a large number of interrelated variables and a substantial amount of work has been carried out over many years to attempt to alleviate the problem. Little work however has been reported on the nature of the fluid flow around the seal; this is determined by seal chamber geometry and affects the removal of potentially deleterious heat, vapour or gases, and solids. At present, many seals are required to run in "stuffing boxes" - cavities designed for soft packing rather than mechanical seals. The aim of this project has been to study the flow behaviour in these stuffing boxes and a number of novel chamber designs. The techniques involved using transparent housings and direct measurements of convective heat transfer coefficients. Significant improvements over existing designs were achieved using a housing flared at 45° away from the seal and this design forms the basis of recommendations for improved seal systems. This design was tested under simulated field conditions described in a Design Study and Case Study and found to be successful. The recommendations are backed up by a mathematical model of turbulence viscosity which seeks to explain some of the complex structured flows observed. A corollary to the thesis explains how the results of this work will form a major input to improved international standards.Item Open Access Gas liquid mixing in tall vessels fitted with multiple impellers(1992-10) Whitton, M. J.; Sanderson, M. L.The dispersion of air into water was studied in a tall agitated vessel (ungassed liquid depth = 2.4 x vessel diameter) fitted with four different triple impeller combinations: 1. Three identical Rushton turbines 2. One Rushton turbine + 2 pitched blade turbines (both pumping down) 3. One Rushton turbine + 2 pitched blade turbines (both pumping up) 4. One Rushton turbine + 2 LE20 impellers (both pumping down) Two vessel scales, of identical geometry, were studied: 1. 0.61 m diameter, 0.420 m3 liquid volume 2. 0.95 m diameter, 1.570 m3 liquid volume. For a range of impeller speeds and gas flow rates, measurements were made of the power draw for each impeller, gas holdup, liquid mixing rates and mass transfer rates. The impeller combinations were compared on the basis of these parameters. The performance of the individual impellers in each combination were also compared with single impellers mounted in standard geometry vessels. ; In terms of power draw and gas holdup many of the trends observed in standard geometry vessels can be directly applied to tall vessel, multiple impeller geometries. A method of estimating the gassed power draw of multiple Rushton turbines is presented. All impeller combinations studied, produced compartmentalised flow patterns. Aeration was found to have a significant effect on liquid mixing rates, and the magnitude of this effect was a function of the impeller combination used. Liquid mixing with multiple impellers was found to be very complex and geometry specific. Simple staged models, used previously in the literature, were found not to apply to the impeller combinations tested in this thesis. An economic comparison is presented, of the options available for improving mass transfer rates in an existing reactor. For the range of conditions considered, increasing the back pressure in the vessel was generally found to be a cheaper option than increasing the power input from the impellers, increasing the gas flow rate, or enriching the inlet gas.Item Open Access Gas-liquid dispersion in stirred tanks: scale-up and agitator comparison(1987-08) Muskett, M. J.; Sanderson, M. L.This thesis is a description of an experimental study of gas-liquid dispersion in mechanically agitated vessels. The objectives of the project were to investigate scale-up and to compare different agitator types. Three vessels up to 2.67m in diameter were available for test work. The work consisted largely of the measurement of the following parameters : (i) Impeller power demand under gassed and ungassed conditions. (ii) Overall gas hold-up. (iii) Mass transfer coefficient using a dynamic response technique. (iv) Flooding point, especially for Rushton turbine impellers. The influence of scale effects on mass transfer has been discussed in some detail from a theoretical standpoint, especially the influence of liquid depth on the concentration driving force available for mass transfer. The use of specific power input and superficial gas velocity was adequate to correlate both hold-up and mass transfer coefficient, but some second order scale effects appeared to be present which made the correlations in each vessel statistically significantly different from each other. The Rushton turbine showed little difference in dispersion efficiency from the concave turbine. Differences were, however, discovered between pitched blade turbines and Rushton turbines, especially when the pitched blade turbine was pumping upwards. The economics of mixer design has also been considered, and the potential economic value of academic research into energy efficiency has been clearly demonstrated.Item Open Access The improvement of meter performance of EM sensing flowmeters using software modelling(Cranfield University, 2008-10) Lim, Sungtaek; Sanderson, M. L.This thesis is focused on the improvement of the meter performance and power consumption of non-mechanical flowmeters such as the conventional electromagnetic flowmeter and the fluidic oscillator. Each flowmeter is studied using Finite Element Modelling for the magnetic field, the virtual current and the fluid dynamics in order to simulate flow signal. The meter design of the conventional electromagnetic flowmeter is modified to provide a better signal level by optimising the geometry of the flow channel and the magnetic field. The signal level increase can be used to reduce power consumption. This improvement provides a 1.96 times greater signal or 51% less power consumption for the conventional electromagnetic flowmeter. An alternative coil-less electromagnetic flowmeter is proposed to reduce the energy consumption. A laminated magnetostrictive material/PZT piezoelectric material is used to control the magnetic field from a permanent magnet. Modelling is carried out to optimise the meter and the magnetic field control device. The device can provide a further reduction of 54.7% of energy usage over the improved conventional electromagnetic flowmeter. The modelling of the fluidic oscillator is undertaken not only with the fluidic dynamics but also the flow signal by using the electromagnetic sensing technique. Using these approaches, recommendations for a better signal level are proposed.Item Open Access Mixing and chemical reaction in tubular reactors and stirred tanks(Cranfield University, 1992-11) Hannon, J.; Sanderson, M. L.Fluid flow patterns and turbulence levels are instrumental in determining chemical reactor performance. Parameters such as stirrer type and size, fluid physical properties, chemical species concentrations and flow rates can strongly influence the safety, efficiency and reliability of reactors, with consequent cost implications. In this project, Computational Fluid Dynamics has been used to obtain insight into the characteristics of tubular and stirred tank chemical reactors. Attention is focused on single phase liquid isothermal turbulent flows. Turbulence theory is used to select and develop appropriate physical models for both fluid flow and chemical reaction rates. Many previously used models are shown to be of limited validity. Results of simulations are compared with experimental measurements of the flow field and progress of both simple and complex chemical reactions. Comparisons are generally favourable. Limitations of the present approach are highlighted and future refinements and extensions suggested.Item Open Access Modelling of piezoelectric ultrasonic transducers with application to high speed gas flow measurement(Cranfield University, 1991-07) Guilbert, A. R.; Sanderson, M. L.The design and testing of an ultrasonic time of ight Mach number probe for use in the bypass duct of an aircraft gas turbine is presented. Analysis of the time and frequency domain behaviour of the type of thickness mode transducers selected for use in the probe, and the effects of beam profile and attenuation on the transmitted ultrasonic wave in a owing medium are also covered and extended. The results of this analysis are implemented in a computer model which is used to aid in the design of various parts of the probe. Experimental assessment of the transducers designed for the probe is presented together with the results of tests on the performance of the selected probe configuration. A digital signal processing system to control the probe and compensate for the poor signal to noise ratio of the received signal is developed together with analogue circuitry to interface this system to the transducers. A novel method of compensating for the beam sweep encountered at the Mach numbers to b measured using 'ski-ramps' is then developed and implemented. Results from the final configuration including the ski-ramps is then presented.Item Open Access Multiphase flow measurement in the slug regime using ultrasonic measurement techniques and slug closure model(Cranfield University, 2006-06) Al-Lababidi, Salem; Sanderson, M. L.Multiphase flow in the oil and gas industry covers a wide range of flows. Thus, over the last decade, the investigation, development and use of multiphase flow metering system have been a major focus for the industry worldwide. However, these meters do not perform well in slug flow conditions. The present work involves experimental investigations of multiphase flow measurement under slug flow conditions. A two-phase gas/liquid facility was designed and constructed at Cranfield University. It consisted of a 0.05 m diameter 25 m long horizontal pipeline with the necessary instrumentation. An ultrasonic multiphase metering concept has been proposed and investigated. The concept was based on the combination of non-invasive and non-intrusive ultrasonic sensors and a slug closure model. The slug closure model was based on the "slug unit" model to infer the gas and liquid phase volumetric flowrates. The slug characteristics obtained by non-invasive and non-intrusive ultrasonic techniques were inputs to slug closure model which calculates the factors KI (Liquid), K2 (Liquid), K3 (Gas) and K4 (Gas). These factors are function of the slip ratio in the slug body, flow profile (CO), drift velocity (Vd), liquid holdup and gas void fraction in slug body, slug length, film length, and the total length of the slug unit. Based on ultrasonic sensor measurements, the slug translational velocity was estimated and the slug closure model then calculates the gas and liquid phase volumetric flowrates. Air water slug flow data were gathered and processed for a range of superficial velocities VSL=0.3 to 1.03 ms'1 and VsG=0.6 to 3.01 ms'1. The overall goal of a 5% relative error metering for both phases was not achieved for the conditions tested. The liquid phase percentage errors were from -63.6% to 45.4% while the gas phase percentage errors were from 42% to -14.6%. Key words: slug flow, slug characteristics, slug closure model, non-invasive ultrasonic, non-intrusive ultrasonic, clamp-on transit time ultrasonic flowmeter.Item Open Access Perfomance enhancement of a fluidic oscillator(Cranfield University, 1996-01) Furmidge, Neil; Sanderson, M. L.The operational performance criteria of fluidic oscillators are described in relation to the requirements of a domestic water meter. The problems associated with developing a novel water meter using fluidic oscillatory technology are discussed and the performance enhancements required to develop a fluidic oscillator capable of meeting the BS5728 (1979) domestic water meter specifications are presented. A sensingc onfigurationi s describedw hich providesa dequates ensitivityo ver the range required for a water meter with a nominal flowrate of one cubic meter per hour. The nozzled imensionsa re investigatedto reducet he pressured rop acrosst he fluidic water meter whilst still maintainingt he requiredt urndown rangea nd adequates ensitivity at low flowrates. The development of a novel fluidic oscillator flow conditioning device is described which radically improves the linearity of the fluidic oscillator and helps to reduce susceptibilityt o upstreamd isturbancesT. he device allows debris to passt hrough the meter without causing blockage and has an acceptable low pressure drop. Modificationst o the fluidic oscillatort ransducegr eometrya rei nvestigatedw hich reduce the minimum point of oscillation, thus increasing the turndown range of the water meter. Also geometry modifications are developed which improve the strength of the jet oscillation at low flowratesa nd therebys ignificantly increaseth e strengtho f signal. The effects of geometry modification on meter linearity and meterfactor response are investigated and a transducer design with enhanced range performance and improved linearity is described. Transducer designs are presented which are capable of meeting the BS5728 (1979) specification for both Class C and Class D QNLO domestic water meters.Item Open Access Theoretical and computation modelling of polymer seal life(Cranfield University, 1993) Ho, Tsz Hang Emily Ting; Hemp, J.; Mapes, J.; Nau, Bernard; Sanderson, M. L.Elastomer seals are widely used in the petroleum industry. Seal failure can be very expensive, due to losses in production and high maintenance costs. Another aspect of this problem is the difficulty in predicting the working life, of a specific elastomeric seal in a specific application, at the design stage. The objective of the present work is to develop the theoretical and computational seal life model to assist reliable prediction of seal life. Seal life computer software has been developed to model fluid ingress into elastomeric seals and the resulting long term material property changes caused by volume swell and chemical reaction between elastomer and ingressed fluid. The approach used is to model diffusion using a finite element method. This permits application to a wide range of seal geometries. The mathematical model of diffusion is coupled with chemical reaction equations of second order to model chemical ageing processes in the seal. To model the effects of swell, volume of absorbed fluid is coupled with Young's modulus. Physical, as opposed to chemical, stress relaxation is not incorporated since the short time scale of this enable direct measurements to be made. The software has been tested against experimental data for a number of elastomer / operating condition combinations. Satisfactory agreement is obtained for ethylene propylene diene (EPDM) and nitrile rubber aged in air or high pressure water; nitrile and hydrogenated nitrile rubber (HNBR) aged in high temperature, high pressure hydrocarbon liquid. The software has also been found useful for calculating required soak time in planning rig tests for the study of explosive decompression caused by absorbed gas in elastomers. Pending further development of the software, long term prediction of retained sealing force of O-rings in high temperature, high pressure water is calculated from compression set by a semi-empirical approach. Results are compared with experimental data.Item Open Access Two-phase slug flow measurement using ultra-sonic techniques in combination with T-Y junctions(Cranfield University, 2010) Khalifa, K. M.; Sanderson, M. L.The accurate measurement of multiphase flows of oil/water/gas is a critical element of oil exploration and production. Thus, over the last three decades; the development and deployment of in-line multiphase flow metering systems has been a major focus worldwide. Accurate measurement of multiphase flow in the oil and gas industry is difficult because there is a wide range of flow regimes and multiphase meters do not generally perform well under the intermittent slug flow conditions which commonly occur in oil production. This thesis investigates the use of Doppler and cross-correlation ultrasonic measurements made in different high gas void fraction flow, partially separated liquid and gas flows, and homogeneous flow and raw slug flow, to assess the accuracy of measurement in these regimes. This approach has been tested on water/air flows in a 50mm diameter pipe facility. The system employs a partial gas/liquid separation and homogenisation using a T-Y junction configuration. A combination of ultrasonic measurement techniques was used to measure flow velocities and conductivity rings to measure the gas fraction. In the partially separated regime, ultrasonic cross-correlation and conductivity rings are used to measure the liquid flow-rate. In the homogeneous flow, a clamp-on ultrasonic Doppler meter is used to measure the homogeneous velocity and combined with conductivity ring measurements to provide measurement of the liquid and gas flow-rates. The slug flow regime measurements employ the raw Doppler shift data from the ultrasonic Doppler flowmeter, together with the slug flow closure equation and combined with gas fraction obtained by conductivity rings, to determine the liquid and gas flow-rates. Measurements were made with liquid velocities from 1.0m/s to 2.0m/s with gas void fractions up to 60%. Using these techniques the accuracies of the liquid flow-rate measurement in the partially separated, homogeneous and slug regimes were 10%, 10% and 15% respectively. The accuracy of the gas flow-rate in both the homogeneous and raw slug regimes was 10%. The method offers the possibility of further improvement in the accuracy by combining measurement from different regimes.Item Open Access Wet gas flow metering with pattern recognition techniques(2004-04) Jama, Ali Ahmed; Sanderson, M. L.The development of many gas condensate fields and the increasing number of marginal fields whose economics do not support conventional bulky separation and processing facilities means that new wet gas flow metering techniques are becoming of greater importance to the oil and gas industry worldwide. For the purpose of this research wet gas flow is defined as multiphase flow (gas-liquid) having in-situ gas volume fraction greater than 95 % at the point of measurement. This research presents a novel wet gas measurement technique involving the use of a standard Venturi meter together with advanced pattern (PR) recognition methods for the detection of liquid presence in wet gas flow conditions and the simultaneous measurement of gas and liquid flow rates without the need for preconditioning of the flow or prior knowledge of either phase. The technique involves four major steps: 1) collection of experimental data spanning the range of flow regimes likely to be encountered in wet gas flow conditions; 2) extraction of flow dependent variables from the Venturi pressure sensors in the form of features; 3) development of PR model for mapping between input features and corresponding gas and liquid flow rates; 4) generalisation test to new and previously unseen flow conditions to determine the accuracy of the Venturi-PR methods developed in this research work. Data was sampled at 50 Hz using two axial differential pressure sensors and one singleend absolute pressure sensor on a 2-inch horizontally mounted Venturi meter using airwater at normally atmospheric conditions. Extensive features were extracted from the time and frequency domains of the raw data and evaluated for their discriminatory ability between different flow conditions. A Bayesian multi layer perceptron (MLP) neural network was used to construct a non-linear mapping between the different feature vectors and the corresponding gas and liquid flow rates using a correctly labelled training data. When the generalisation performance of different measurement scenarios developed was tested, the cross-sensor data fusion of the amplitude features achieved 100 % of the test data to within ± 5 % error across the whole flow domain of interest. The Venturi-PR results also performed significantly better than published wet gas differential pressure flow correlations over the flow domain of interest.