Studies Of Velocity Profile In Single Pahse And Multiphase Flows By Using Multielectrode Imaging Electromagnetic Flow Meter

The main objective of the research described in this thesis is to develop a novelnon-intrusive flow m easurement instrument for measuring liquid flow rate in highlydeviated velocity profile in single phase and particularly in m ultiphase flow. Themultiphase flow phenomena are com monly encountered in industries such as petrol,power, chemical, metallurgy and m edical. It is of great significance to research onaccurate detection of parameters in highly deviated velocity profile.This thes is describ es a Multiele ctrode Im aging Electromagnetic Flow Meter(MIEF) which is based on a novel area weight value theory. The MIEF is capable ofprofiling local axial water velo city profile in highly non-un iform flow distribution inwater flow and solids-water flows. In multiphase flows, it is essential to measure thevolumetric flow rate of specific phase whic h is revealed by integrating the product oflocal pha se velocity a nd the loca l phase volum e f raction in the f low transver secross-section.Extensive investigation in simulation of magnetic flux density distribution in theflow cross-section is presented which allo ws the Helm holtz coil geo metry to beoptimised. The MIEF is modelled in COMSOL multiphysics simulation software. Thenovel area weight value theory is implem ented in the sim ulation and verified by thereconstructed velocity results both in num erical and experim ental. The ef fect of thevelocity profiles on the elec trical potential distributions under uniform magnetic fluxdensity distribution in the flow cross-sectio n is p resented. The reconstructionalgorithms for re constructing the local axial velocity from the m easured electricalpotential differences via the novel area wei ght value theory are presented. The VM1microcontroller is introduced into the on-line measurement system as a processing andcontrolling core.The MIEF system is u sed extensively to inv estigate hig hly deviate d veloc ityprofile in single phase flows and vertical and in clined solids-water two phase flows,the experimental results are validated with conventional Pitot sta tic tube system insingle phase flows and six-electrode local probe in solids-liquid flows. The outcomesof the MIEF system show very prom ising future for the flowm eter technology inmultiphase flow measurements.