Flowmetering by a motion-induced magnetic field

Abstract

A two-dimensional model of an `induced-magnetic field' flowmeter is described. A thin capsule, containing field- and search-coil wires, is embedded in the fluid, the wires being arranged for zero signal on the search coil when there is no flow. The response of the meter depends on the magnetic Reynolds number (Re)M, which involves the electrical conductivity and velocity of the fluid, and on a parameter S, which is the ratio of characteristic length to skin depth. Analysis shows how the response varies with (Re)M and S. It is suggested that operation at very high and low values of (Re)M should be avoided, a suitable range being 1-4; optimum values for S are in the region of 2.