Numerical and experimental study of divergent magnetic fluid seals with stepped pole pieces

It is crucial that the pressure resistance of ordinary magnetic fluid seals is under small clearance conditions. Therefore, a new structure for magnetic fluid seals, i. e. a dispersion type with stepped pole pieces, is proposed in this paper to further improve the pressure resistance under such operating conditions. For the divergent magnetic fluid seal with stepped pole piece, the magnetic field distribution in the clearance can be calculated, as well as the theoretical pressure resistance of the new seal structure. In this paper, it is calculated the magnetic field distribution and theoretical pressure resistance utilizing the magnetic field finite element method based on the theory of divergent magnetic fluid seals, investigated the influence of the amount of injected magnetic fluid, the number of steps, the height of the steps and the sealing gap on the pressure resistance of the new sealing structure of stepped magnetic fluid seals, as well as compared and analyzed with that of ordinary magnetic fluid seals and normal magnetic fluid seals. The results show that the pressure resistance of the normal magnetic fluid seal is significantly worse than that suggested by the split magnetic fluid seal. The pressure resistance of the stepped magnetic fluid seal increases as the number of steps increases, while the pressure resistance of the proposed structure decreases and then increases as the height of the steps increases; and the pressure resistance of the proposed structure increases and then decreases as the radial clearance increases, while the pressure resistance of the proposed structure decreases as the axial clearance increases.