Research On Distribution And Detection Of Electromagnetic Flowmeter Magnetic Field

Thermal capacity includes flow, temperature, pressure and displacement. Among these, the flow measurement is so inextricably linked with people’s lives that the flow meter is widely used. And the electromagnetic flowmeters are welcomed, because of its fast measurement speed, high precision. However, in the researches of the electromagnetic flowmeter, the design of excitation system structure does not fully meet the distribution requirements of the weighting function, also, there are accuracy problems when using the dry calibration technique in the actual application.With the analysis of the problems, the key to solving these problems is to accurately and efficiently detect distribution information of electromagnetic flowmeter magnetic field. Therefore, the paper is around the distribution of the electromagnetic flow meter magnetic field and the detection technology to conduct researches and completed the following work.(1) Electromagnetic flowmeter theory and the key technologiesThrough researching on the basic working principle and mathematical model of electromagnetic flowmeter, analysis of different distribution of the weighting function between the long-barreled and short-tube flowmeter, and studying the effects on the distribution of the electromagnetic magnetic field, the paper lays a theoretical foundation for excitation system structure of the weight conversion magnetic field. Also, the structure of the electromagnetic flowmeter and the electromagnetic flow sensor are studied.(2) Detection technology on distribution of electromagnetic flowmeter magnetic fieldAccording to the characteristics of electromagnetic flow sensor structure and the magnetic field distribution, the paper designs a detection system on distribution of magnetic field. The main function of the detection system include:magnetic field intensity and the acquisition of corresponding point coordinates, data collection, processing, storage, and three-dimensional imaging. The structures of detection system is the joint work mode of the master and slave. And the slave include:gauss sensor and its drive circuit, High-precision signal amplification processing system, A/D conversion module, method of communication and the communication protocol between the master and slave, the human-machine interaction and so on. The master is programmed by the combination of Visual Basic and Matlab, and includes PC interface and the function module, data acquisition and control system, database storage, as well as three-dimensional imaging.(3) Exploration of the electromagnetic flowmeter excitation systemThrough researching on the current electromagnetic flowmeter excitation system, the paper finds that the practical application of the excitation system does not fully meet the distribution of the weighting function requirements. Therefore, the paper uses the self-designed distribution detection system of magnetic field to improve the existing short-rectangular, saddle-like excitation structure, and trys to figure out the excitation structure of the weight function distribution.