Numerical calibration of a multicomponent local Lorentz force flowmeter

D. Hernández¹ - T. Boeck¹ - C. Karcher¹ - T. Wondrak²

¹ Institute for Thermodynamics and Fluid Mechanics, Technische Universität Ilmenau, 98684 Ilmenau, Germany
² Institute for Fluid Dynamics, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany

Abstract
Local Lorentz force velocimetry is a local velocity measurement technique for liquid metals. Due to the interaction between an electrically conducting liquid and an applied magnetic field, eddy currents and flow-braking Lorentz forces are induced in the fluid. Due to Newton's third law, a force of the same magnitude acts on the source of the applied magnetic field, which is a permanent magnet in our case. The magnet is attached to a gauge that has been especially developed to record all three force and three torque components acting on the magnet. This new-generation local Lorentz force flowmeter (L2F2) has already been tested in a test stand for continuous casting with a 15 mm cubic magnet providing an insight into the three-dimensional velocity distribution of the model melt GaInSn near the wide face of the mold. For better understanding of these results, especially regarding torque sensing, we propose dry experiments which consist in replacing a flowing liquid by a moving solid. Here, as the velocity field is fixed and steady, we are able to decrease considerably the variability and the noise of the measurements providing an accurate calibration of the system. In this paper, we present a numerical study of this dry calibration using a rotating disk made of aluminum and two different magnet systems that can be shifted along the rotation axis as well as in the radial direction. Tables 1, Figs 7, Refs 7.