To improve the pressure capacity of the magnetic fluid seal with a large sealing gap, a new type of stepped magnetic fluid seals was firstly proposed based on magnetic fluid seal with multiple magnetic sources or stepped labyrinth seals. A universal magnetic fluid seal with two permanent magnets and a diverging stepped magnetic fluid seal have been investigated by experimental methods. The experimental results of the both sealing structures have been compared and analyzed. The results indicate that the diverging stepped magnetic fluid seal shows good performance compared to the universal magnetic fluid seal without stepping structure and it is an effective method to improve magnetic fluid sealing capacity with a large gap.
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