The Modeling And Imaging Algorithm Research Of A Multi-electrode Electromagnetic Blood Flowmeter

The fluid flow is one of the most common control parameters in the process of industrial control testing, with the development of technology and research methods, the flow measurement opens up a new research field. In this paper, the electromagnetic flowmeter for flow measurement was applied to monitoring of blood flow, by deriving the induction enectromotive force of the insulation of the outside walls of blood vessels; the electromagnetic blood flowmeter can measure the blood flow velocity.Firstly, this paper introduces the relevant theories of electromagnetic flowmeter,including the traditional two electrodes electromagnetic flowmeter and multi-electrode electromagnetic flowmeter. Based on Sherliff weight function, the concept of regional weight function is introduced and the derivation process of the regional weight function is introduced in detail as well as the multi-electrode electromagnetic flowmeter measurement equation. The regional weight function theory suggests that the flow velocity of measurement section in different area contribution to the induction electromotive force between different electrodes, at the same time, the theory of multi-electrode electromagnetic flowmeter solves the limitations of traditional two electrodes to the electromagnetic flowmeter measurement.Secondly, estensive investigation in simulation of magnetic flux density distribution in the flow cross-section is presented between Helmholtz coil and C-type coil which are proposed for the selection of the excitation coil. The multi-electrode electromagnetic blood flowmwter is modeled in COMSOL Multiphysics simulation software which based on finite element analysis method; the regional weight function is calculated. The reconstruction algorithms for reconstructing the velocity distribution are discussed, and finally the Tikhonov regularization principle is chosen. From three aspects of the model are discussed: grid, solver and electrode array.Thirdly, according to the characteristics of the blood flow velocity, the measuring section is divided into several different ways.The areas that instead of the vein and aorta,reconstruct the speed by COMSOL simulation and reconstruction algorithms.The regional partition are studied from 8 electrodes and 16 electrodes respectively.Lastly, this paper also designs the excitation system and choses the C-type coil as the excitation coil. In order to reduce the leakage, chosing a 0.3mm thick silcon steel lamination is selected instesd of ircon core, and the air gap magnetic induction intensity iscalculated. In view of the actual laboratory conditions and the surrounding environment,uniform scope of magnetic induction intensity of the air gap has carried on the simulation analysis so as to keep the measurement datas authenticity and accuracy.