Study on Process Tomography through Electro-Magnetic Induction for Nonsteady Flow

非定常流电磁感应过程层析成像研究

基本信息

批准号：
14550426
负责人：
HONDA Satoshi
金额：
$ 1.86万
依托单位：
Keio University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

项目摘要

Electromagnetic flowmeters using Faraday's law have been one of the standard meters to measure liquid flowrate in industry. A conventional electromagnetic flowmeter has a uniform magnetic field and point electrodes in a circular pipe. Such a flowmeter has a flow signal which is proportional to the flowrate when the velocity profile in the liquid is axisymmetric. The ideal field which induces the flow signal proportional to the flowrate free from velocity profile does not exist. Conversely, it is possible to evaluate velocity profiles through the proper design of the magnetic field.In previous study 2-dimensional tomography system with eight magnetic poles and eight signal pickup electrodes was reported. It was reported that when the flow was conditioned to be fully developed and axially symmetric, the reconstruction of 2-dimensional velocity distribution could be achieved from induced signals. In this paper, the author proposes a new design of the 3-D field excitation with two sets of eight magnetic poles and of eight signal pickup electrodes. This research aims at the estimation of 3-dimensional velocity distribution in the pipe. For numerical simulation the laminar swirling flow was supposed. The axial component is the same as Poiseuille flow. The tangential velocity components represent a swirl. In order to reconstruct the tangential velocity, the constraints of non-slipness at the pipe wall, equation of continuity, and tangential velocity near the wall were effective. A new method for reguralization parameters is proposed. The proposed method applies to L-curved one. When there are two reguralization parameters, the parameter surface is described in 3-D space. The reguralization parameters were determined by the proposed method. It is concluded that the reconstruction of 3-D velocity distribution can be achieved from induced signals. Numerical simulation study showed the feasibility of the 3-D flow velocity tomography.

利用法拉第定律的电磁流量计已成为工业上测量液体流量的标准仪表之一。传统的电磁流量计具有均匀磁场和位于圆形管道中的点电极。当液体中的速度分布是轴对称时，这种流量计具有与流量成比例的流量信号。不存在不受速度分布影响而产生与流量成比例的流量信号的理想场。相反，可以通过正确的磁场设计来评估速度分布。在之前的研究中，报道了具有八个磁极和八个信号拾取电极的二维断层扫描系统。据报道，当流动被条件充分发展和轴对称时，可以从感应信号实现二维速度分布的重建。在本文中，作者提出了一种新的 3-D 场激励设计，具有两组 8 个磁极和 8 个信号拾取电极。本研究旨在估计管道中的三维速度分布。对于数值模拟，假设层流旋流。轴向分量与泊肃叶流相同。切向速度分量代表漩涡。为了重建切向速度，管壁处的防滑性、连续性方程和近壁切向速度的约束是有效的。提出了一种新的正则化参数方法。所提出的方法适用于L 形曲线。当有两个正则化参数时，参数表面在 3-D 空间中描述。正则化参数由所提出的方法确定。结论是可以通过感应信号来重建 3D 速度分布。数值模拟研究表明了3D流速层析成像的可行性。