Development And Optimization Of The Magnetic Field Of Electromagnetic Flowmeter

Fluid flowrate is one of the most important measurement parameter in Control Procedure of industrial and agricultural production; therefore, there is a wide range as for bulk meter of flowrate measurement. Take such advantages of simple structure, unimpeded flow of parts, linear measuring principle, high accuracy, wide measuring range, the electromagnetic flowmeter is much more particular favorite for its measurements only relates to the fluid volume other than the fluid density, viscosity, pressure, weight and other parameters. Therefore, as one of tools for measuring the flowrate, the electromagnetic flowmeter is being used more and more.At present, we are far behind the developed country in R & D field of electromagnetic flowmeter. The core technology of electromagnetic flowmeters is almost imported. This dissertation is committed to the development of proprietary products of electromagnetic flowmeter by deep researching on those kinds of products. The main contents are as below:Firstly, the research background and significance of this dissertation is introduced. Based on series of advantages of electromagnetic flowmeter, it conducts the plan for using it in liquid measurement, and illustrates the history, the research development and the future of electromagnetic flowmeter.Secondly, by introduction to measurement principle and detailed analysis to comparison with Maxwell's equations, it lists the fundamental differential equation of electromagnetic flowmeter measurement. In process of solving the equation, weight function is discussed in details. Further, by way of software MATLAB tool, the graphical weight function is illustrated. Moreover, it followed by the discussion of velocity distribution, flowrate, edge effect of the magnetic field those effects of electromagnetic flowmeter.Additionally, it introduces the major components of electromagnetic flowmeter sensor, and explains the measuring tube, linings, electrodes, flanges, excitation system and other major components in details. Besides, according to the actual situation encountered in the experiments, it describes the appropriate materials, structure, assembly methods, manner and frequency of excitation during the process. Meanwhile, in order to reduce the influence of magnetic field to the signal, the measurements for alignment method and ground connection of the signal lead-out etc. are also provided.Finally, to avoiding the impact of velocity distribution to electromagnetic flowmeter, the concept of non-uniform magnetic field of electromagnetic flowmeter is applied. In such condition, the measurement relates to flow rate only, other than the velocity distribution. To obtain such a status, the ideal magnetic field distribution is needed. On basis of Maxwell's equations, the ideal size of coil excitation can be sloved. Under this condition, considering the process of winding the coil, measuring tube thickness and other practical factors, the rectangular and saddle-shaped coil can be obtained. By use of software ANSYS to imitate the two coil magnetic field and comparison.