多电极电磁血液流速仪建模与成像算法研究

发布时间：2018-08-17 18:43

【摘要】：流体流量是工业生产检测控制过程中最为常见的控制参数之一,随着技术手段和研究方法的不断发展,流量测量开拓了新的研究领域。本文将电磁流量计对流量的测量应用于血液流量的监测中,血液电磁流量计通过拾取非绝缘血管外壁上的感应电动势,实现对血液流速的测量。首先本文介绍了电磁流量计的相关理论,包括传统两电极电磁流量计和多电极电磁流量计。基于Sherliff权函数理论引出区域权函数的概念,并详细介绍了区域权函数的推导过程以及多电极电磁流量计的基本测量方程,区域权函数理论表明了测量截面处不同区域内的流动速度对不同电极对间的感应电动势的贡献,为权函数的数值求解提供了依据,同时多电极电磁流量计的理论也解决了传统两电极电磁流量计测量的局限。其次本文针对亥姆霍兹线圈和C型线圈在流动截面处激励的磁感应强度分布进行数值分析,提出了对励磁线圈的选择;采用有限元分析方法对多电极电磁血液流速仪模型在COMSOL Multiphysics中进行建模仿真,并求取区域权函数的数值;通过对速度分布重构的算法进行讨论,选取吉洪诺夫正则化法则;通过对模型在网格划分、求解器以及电极阵列三方面的对比讨论,选取对速度重构效果好的参数设置方式。再次本文针对血液流速的特点对测量截面处划分为几种不同的区域划分方式,通过COMSOL仿真以及速度重构对代替主动脉和和静脉的区域进行了速度重构,区域划分分别从8电极和16电极着手进行研究。最后本文还进行了励磁系统的设计,选取C型线圈。为减少漏磁,用0.3mm厚的硅钢片层压来代替铁芯,并计算出了气隙处的磁感应强度;针对实际实验室条件和周围环境的影响,对气隙处的磁感应强度的均匀范围进行了仿真分析,确定保持测量数据真实性和准确性的范围。
[Abstract]:Fluid flow is one of the most common control parameters in the process of industrial production detection and control. With the continuous development of technical means and research methods, flow measurement has opened up a new research field. In this paper, the measurement of flow rate by electromagnetic Flowmeter is applied to the monitoring of blood flow. The measurement of blood velocity is realized by picking up the inductive electromotive force on the external wall of non-insulated blood vessel. Firstly, this paper introduces the related theories of electromagnetic Flowmeter, including the traditional two-electrode electromagnetic Flowmeter and the multi-electrode electromagnetic Flowmeter. Based on the theory of Sherliff weight function, the concept of regional weight function is introduced, and the derivation process of regional weight function and the basic measurement equation of multi-electrode electromagnetic Flowmeter are introduced in detail. The theory of regional weight function shows the contribution of the flow velocity in different regions of the measurement section to the induction electromotive force between different electrode pairs, which provides the basis for the numerical solution of the weight function. At the same time, the theory of multi-electrode electromagnetic Flowmeter solves the limitation of traditional two-electrode electromagnetic Flowmeter. Secondly, the distribution of magnetic induction intensity excited by Helmholtz coil and C-type coil at the flow section is analyzed numerically, and the selection of excitation coil is put forward. The finite element analysis method is used to model and simulate the multi-electrode electromagnetic blood velocity meter model in COMSOL Multiphysics, and the value of region weight function is obtained, and the regularization rule of Tikhonov is selected by discussing the algorithm of velocity distribution reconstruction. By comparing and discussing three aspects of the model, such as mesh generation, solver and electrode array, a parameter setting method with good effect on velocity reconstruction is selected. Thirdly, according to the characteristics of blood flow velocity, the measurement section is divided into several different regions, and the region instead of aorta and vein is reconstructed by COMSOL simulation and velocity reconstruction. The regional division was studied from 8 electrodes and 16 electrodes respectively. Finally, the excitation system is designed and the C-type coil is selected. In order to reduce magnetic flux leakage, 0.3mm thick silicon steel lamination is used to replace iron core, and the magnetic induction intensity at air gap is calculated, and the uniform range of magnetic induction intensity in air gap is simulated according to the influence of actual laboratory conditions and surrounding environment. Determine the scope to maintain the authenticity and accuracy of measurement data.
【学位授予单位】：河北科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TH776

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