A theoretical model of Lorentz force particle analyzer: a potential flow perspective

Abstract

A Lorentz force particle analyzer (LFPA) is a device for the contactless measurement of micron-sized particles in electrically conducting fluids. The LFPA is based on the measurement of either force or torque changes acting upon a magnetic-generating system when the particle passes near a magnetic field. In this paper, we first formulate the theory of the LFPA using a magnetic dipole with a magnetic field penetrating a particle-laden thin fluid flow layer. The disturbed electromagnetic quantities in the presence of a particle are analytically solved using an approach analogous to that for potential flow, providing a relationship between the measured physical quantities, i.e., force, torque and induced magnetic field, and the particle size. A detailed investigation of physical properties and operating parameters provides a rational framework for predicting the sensitivity of LFPAs in laboratory experiments and in industrial practice.