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Liquid-metal flows induced by low-frequency alternating magnetic fields

Published online by Cambridge University Press:  26 April 2006

J. M. Galpin  and
Y. Fautrelle
J. M. Galpin
Affiliation:
INPG-MADYLAM, B.P. 95X, 38402 Saint Martin d'Hères Cedex, France Present address: IRSID, Station d'Essais, 57210 Maizières-les-Metz, France.
Y. Fautrelle
Affiliation:
INPG-MADYLAM, B.P. 95X, 38402 Saint Martin d'Hères Cedex, France
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Abstract

This paper describes an experimental study of the influence of a low-frequency alternating magnetic field on a liquid-metal pool with a free surface. A 200 mm cylinder containing mercury is located in a solenoidal coil supplied with a single phase a.c. current of frequency 2–20 Hz. It is shown that, in that frequency range, the motion may be split into two parts: (i) a bulk motion driven by the mean Lorentz forces; (ii) a surface wave motion driven by the alternating part of the Lorentz forces.

The turbulent bulk flow is quite similar to those observed in previous electromagnetic stirring experiments at higher frequency. The peculiar feature, observed here, is the rapid decay of the mean characteristic velocity. That phenomenon seems to be related to the presence of fluctuating velocities forced by the alternating electromagnetic force.

The alternating part of the Lorentz forces is globally responsible for a surface motion whose pattern and amplitude depend on the applied electric current I and its frequency f. The (I, f)-parameter space may be split into four regions corresponding to four regimes, namely (i) concentric harmonic standing waves driven by the Lorentz forces, (ii) harmonic azimuthal waves, (iii) strong-amplitude subharmonic azimuthal waves, (iv) chaotic free-surface motion. The wave motion becomes negligible when the frequency is greater than 10 Hz.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 239 , June 1992 , pp. 383 - 408
Copyright
© 1992 Cambridge University Press

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