Electromagnetic Flow-meter Structure Optimization Based On CFD Simulation

Flow measurement plays a very important role in many fields such as chemical industry,energy engineering,and urban water supply and drainage.Among different flow meters,electromagnetic flow-meters(EMF)are widely used due to their wide measuring range,fast response,and convenience for multiphase flow detection.Considering that the measurement signal of the electromagnetic flowmeter is closely related to the flow state of its internal fluid,this paper will focus on improving the internal flow distribution in the flow-meter of various electromagnetic flow-meter structures.Large eddy simulation(LES),as an advanced CFD method,was adopted to optimize the electromagnetic flow-meter,and the optimized structure was verified through experimental results.This paper analyzes the flow fields in the electromagnetic flow-meters with straight-circular lining and the octagonal lining,respectively.Due to the shape of the lining and the electrode,the velocity fluctuation near the circular lining electrode is stronger than that near the octagonal lining electrode.Octagonal lining,in combination with the flat top electrode,can effectively reduce the velocity fluctuation near the electrode,which can improve the measurement stability and accuracy of the electromagnetic flow-meter.To intensify the installation adaptability of the electromagnetic flow-meter when the practical arrangement space is limited,we propose a 90 ° bent type electromagnetic flow-meter with the plug-in electrode based on the straight-tube electromagnetic flow-meter.By comparing the velocity distribution near the flat-end electrode and the sharp-end electrode by simulation and comparing the electrical signals measured by the flat-end electrode and the sharp-end electrode by experiment,we can see that the measurement error of the sharp-end electrode is smaller than that of the flat-end electrode,and the measurement range is larger than that of the flat-end electrode,so the measurement performance of the sharp-end electrode is better.The velocity fluctuation between electrode wall and tube wall is highest,and therefore,the strong magnetic field should be avoided being stimulated here via the appropriate installation of the coils.Moreover,based on the original contraction section of the flow-meter,two new types of inlet contractive sections are proposed,which are a linear tapered section and a Vyshinsky curve tapered section.It is found that the Vyshinsky curve contraction section is more capable of stabilizing the internal flow field of the pipeline.