A numerical approach to the determination of electromagnetic flow meter weight functions

Abstract

A new finite element procedure for the solution of the electromagnetic flow meter weight function is presented. The weight function represents the relative contribution of the fluid velocity at a particular spatial location in the flow cross section to the output signal from the flow meter. The solution of the weight function is important for inferring the velocity profile from measured potential differences within the electromagnetic flow meter. First, a numerical simulation model was constructed with COMSOL Mutiphysics [1]. Next, a study was undertaken to compare the numerical simulation model with Shercliff's [2] analytical solution for the weight function. The finite element methodology was found to be correct for solving the weight function. Based on this result, the numerical simulation model was used to compute the weight function for two flow meter geometries. For both cases the electrodes were located on the internal circumference of the flow pipe and the line joining the electrodes was normal to the imposed magnetic field. In the first case the separation of the electrodes was equal to one pipe diameter but in the second case the electrode separation was less than one pipe diameter. The methodology presented in this paper represents the first stage in the development of an image reconstruction technique which could be used to obtain the liquid velocity profile from boundary voltage measurements obtained in flows with highly skewed velocity distributions.

Measurement and control systems for an imaging electromagnetic flow metre

“…The good agreement between the two techniques indicates the veracity of the numerical method used in this paper for determining ij w . This agreement has also previously been reported in [14]. and so, when calculating 44 w , very small regions in the immediate vicinity of these two coordinates must be excluded from the calculation).…”

Electromagnetic Flow Detection Technology Based on Correlation Theory

“…J.Z.Wang et al proposed a new finite element method to solve the weight function of electromagnetic flowmeter. It can reduce the influence of magnetic field interference when the fluid contains a certain proportion of solid particles [17].…”

The Influence of Admixtures to the Signal of an Electromagnetic Flow Meter

“…Bevir [2], which allows for accurate estimation of the influence of every flow point over the measurement signal. The ability of assessing the sensitivity to velocity distribution [3], the influence of channel electrical properties on calibration [4,5], including the case when closed pipe is not completely filled [6], and setting of weighting functions has been simplified [7]. The concept of virtual current is also widely used for measuring multiphase flow with EMFM [8].…”