Mechanical Properties of a Ferrofluid Seal: Three-Dimensional Analytical Study based on the Coulombian Model

Romain Ravaud (1) , Guy Lemarquand (1)

1 LAUM - Laboratoire d'Acoustique de l'Université du Mans

This paper presents a general method for studying the mechanical properties of a ferrofluid seal by using a three-dimensional analytical approach based on the coulombian model of a magnet. The fundamental Maxwell's equations lead us to define the concept of magnetic energy of the ferrofluid seal by using only the three-dimensional equations of the magnetic field created by ring permanent magnets radially magnetized. Our study corresponds to the specific case when the ferrofluid is submitted to a very high magnetic field. Under these conditions, the mechanical properties of the ferrofluid depend only on the magnetic field created by the permanent magnets. Throughout this paper, the remanence polarization J of the magnets used is higher than 1T. The magnetic field we use in order to align the magnetic particles is very intense, greater than $400$~kAm$^{-1}$. Consequently, the magnetic particles are assumed to be saturated and the magnetic field they create can be omitted.

Mots clés: ferrofluid seal; ironless loudspeaker; anaytical calculation; magnetic energy; three-dimensional

Domaines: Acoustique [physics.class-ph]; Acoustique [physics.class-ph]; Electromagnétisme

Romain Ravaud, Guy Lemarquand. Mechanical Properties of a Ferrofluid Seal: Three-Dimensional Analytical Study based on the Coulombian Model. Progress In Electromagnetics Research B, 2009, 13, pp.385-407. ⟨10.2528/PIERB09020601⟩. ⟨hal-00368285⟩