Continuous phase velocity profile measurement in multiphase flow using a non-invasive multi-electrode electromagnetic flow meter

Abstract

This paper describes a novel design of electromagnetic flow meter for velocity profile measurement in multiphase flows with non-uniform axial velocity profiles. A Helmholtz coil is used to produce a uniform magnetic field orthogonal to both the flow direction and the plane of an electrode array embedded on the internal surface of a non-conducting pipe wall. Induced voltages acquired from the electrode array are related to the flow velocity distribution via variables known as 'weight values' which are calculated using COMSOL Multiphysics software. Matrix inversion is used to calculate the velocity distribution in the flow cross section from the induced voltages measured at the electrode array. The flow pipe crosssection is divided into a number of pixels and the mean flow velocity of the continuous phase in each of the pixels is calculated from the measured induced voltages. Experimental results are presented for the reconstructed velocity profile of the continuous water phase in an inclined solids-in-water multiphase flow for which the axial water velocity distribution is highly non-uniform. The results presented in this paper are most relevant to flows in which variations in the axial flow velocity occur principally in a single direction.