Novel Shield between Magnetic Fluid and Sealed Liquid: A Theoretical and Experimental Study

A novel type of shield, comprising the upper/lower cylindrical rings with identical height and outer diameter but with different inner diameters, was developed to improve the stability at the interface of magnetic fluid and sealed liquid medium.The influence of the ring height, shaft's rotating speed and sealing gap, on the complete sealing time was theoretically analyzed in Kelvin-Helmholtz instability theory and experimentally investigated with the lab-built test platform.The experimental results show that the new shield significantly increased the zero leakage sealing time.To be specific, under the optimized conditions, including a ring height of 10 mm, a sealing gap of 0.05 mm and a rotation speed of 2000 r/min, the magnetic fluid seal with the new shielding rings displayed zero leakage after continuous operation for 120 h.