Computation of electromagnetic flowmeter characteristics from magnetic field data

Abstract

A description is given of a method which may be used to predict the performance of a flowmeter subject to certain constraints. The flow channel is an insulating cylinder of circular cross-section, the contact electrodes are assumed to be mathematical points and the flow is restricted to the rectilinear axisymmetric case. The analysis includes the effect of a concentric annular stationary medium surrounding the liquid, but of different conductivity. The magnetic field may have any form, and this is found experimentally by measuring its normal component at a number of points on the cylindrical surface bounding the flow channel. The mathematical basis of the method is given, together with an outline of the computation and a description of the apparatus used to measure the magnetic field. The method can be used both as a means of 'dry calibrating' a given flowmeter and as an aid to flowmeter design.