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Introduction to the measurement principle of electromagnetic flowmeter

The electromagnetic flowmeter is a meter that measures the volume flow of a conductive liquid according to the working principle of Faraday's electromagnetic induction law. Macroscopically, the conductive liquid is regarded as a conductor, and the flow of the fluid is regarded as a conductor for cutting magnetic field lines. In fact, the measurement of the flow rate of a conductive liquid by electromagnetic induction is much more complicated than the movement of a solid conductor in a magnetic field. As the particle of space, the vector field of magnetic induction is in a limited uniform range, and the flow of conductive liquid can only be the movement of particles in a continuous medium. The velocity of the contiguous medium in the flow channel is also a vector form, and the velocity distribution within the pipe is a complex problem. These complex problems can only be answered with certain preconditions. Therefore, using only the principle of the law of electromagnetic induction, the interpretation of the essence of the electromagnetic flowmeter cannot be truly satisfactory. Therefore, the scholars behind Faraday attribute the theory of electromagnetic flowmeter to the discipline of magnetohydrodynamics. It is the product of a combination of fluid mechanics and electromagnetics. In practical industrial applications, electromagnetic flowmeters are often used to measure electrolyte fluids. At low operating magnetic field frequencies, metal measuring electrodes are inevitably producing polarization voltages, and arms such as slurry measurement have a low-conductivity measurement of low-conductivity measurement. Therefore, it is also necessary to relate to the theory of electrochemistry and the like. Discussing the basic theory of electromagnetic flowmeters is often inseparable from many formulas and citations of electromagnetics and fluid mechanics. These contents are quite boring and are not needed for many practical applications. In order to facilitate the reader to understand the working principle of the electric flowmeter, we just clarify some of its main theoretical problems, explain their physical meaning, and try to avoid the complicated formula derivation and argumentation. However, if deep people understand and deeply understand the electromagnetic flowmeter, it is necessary to learn and study its theory to take the opportunity to publish this book. We will give a speech by Mr. Wang Xi in a very small scope in 1975. Theory of a power flowmeter"

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