Effect of shaft speed on performance of magnetic fluid seal with gas isolation for sealing water

When applied to seal liquid, magnetic fluid seal was prone to failure with the increase of shaft speed because of instability at the interface of these two fluids caused by shaft rotation. In order to avoid this problem, a new type of magnetic fluid seal was proposed, in which the magnetic fluid was separated from the sealed liquid by gas. The sealing principle of the structure was studied. Gas-liquid two-phase flow in the structure was simulated by computational fluid dynamics. A test rig of magnetic fluid seal with gas isolation was set up. Experiments of pressure resistance and seal durability of the original structure and structure with gas isolation for sealing water were carried out on the test bench. The results of theoretical analysis, CFD and experiments indicated that: there was no obvious relationship between shaft speed and performance of magnetic fluid seal when gas isolation was added for sealing water. Its pressure resistance was almost the same as that of the structure sealing gas. Its seal durability was significantly longer.