Experimental study on the critical pressure of converging ferrofluid seal with alternating pole teeth

Abstract

For the improvement of pressure capability in ferrofluid seal with a small gap, a structure of converging ferrofluid seal (CFS) with alternating pole teeth is proposed in this study. Distribution of magnetic field in this structure is analyzed by using finite element method, and then theoretical values of withstanding gas pressure are calculated. The influence of ferrofluid volume, sizes of radial and axial sealing gap, numbers of radial and axial pole teeth on the critical pressure of CFS with alternating pole teeth is studied on the test bench. Then experimental results are compared and analyzed with the experimental pressure resistance of ordinary stepped ferrofluid seal. It is demonstrated that the calculated value of pressure resistance of the CFS with alternating pole teeth fits well with the experimental data. The volume of the injected ferrofluid can reach saturation. The sealing performance of CFS with alternating pole teeth is related not only to the clearance between pole teeth and stepped shaft, but also to the number of radial and axial pole teeth. The sealing performance of CFS with alternating pole teeth is better than that of ordinary stepped ferrofluid seal.