Theoretical And Experimental Research Of Magnetic Fluid Seal With Large Gap And Stepped Rotary Shaft

:To improve the pressure capability of magnetic fluid seal with large gap, a novel stepped magnetic fluid sealing structure was proposed. The pressure mechanisms of the diverging and converging stepped magnetic fluid seal were investigated by the experimental and numerical methods. The theoretical pressure capabilities of the diverging and converging stepped magnetic fluid seal derivation were derived on the basis of their pressure mechanisms.The stepped magnetic fluid sealing structure was designed and optimized using the equivalent magnetic circuit method and the magnetic field finite element method.The leak location and magnetic field distribution of the stepped magnetic fluid seal were studied by the magnetic field finite element method. The theoretical pressure capabilities of the diverging and converging stepped magnetic fluid seals were obtained under the different radial and axial sealing gap.Effects of radial sealing gap height, axial sealing gap width, speed, magnetic fluid type and volume on the pressure capabilities of the diverging and converging stepped magnetic fluid seals were studied experimentally. The experimental and theoretical values of the diverging and converging stepped magnetic fluid seals were compared and analyzed. The results indicate that the theoretical results agreed well with the experimental results. The pressure capabilities of diverging and converging stepped magnetic fluid seals increase with the increase of the magnetization of the magnetic fluid, increase with the increase of the magnetic fluid volume and become stable, remain constant with the increase of the rotational speed.The pressure capabilities of non stepped magnetic fluid seal were studied experimentally, compared and analyzed with the experimental results of the stepped magnetic fluid seal. The results show that when the axial sealing gap width is small, the pressure capabilities of the stepped magnetic fluid seals are significantly larger than that of the non stepped magnetic fluid seals. However, when the axial sealing gap width is larger, the pressure capability advantages of the stepped magnetic fluid seals are relatively smaller than that of the non stepped magnetic fluid seals.