A Comparative Study of Ferrofluid Seal and Magnetorheological Fluid Seal

Compared with a ferrofluid (FF) seal used as a sealing material, magnetorheological (MR) fluid has higher sealing pressure at the same condition. This is because MR fluid not only has magnetic property but also shows obviously elasto-plastic performance, which differs from FFs, under the magnetic field. On this basis, this paper analyzed, respectively, the static seal performance of MR fluids and FFs based on their magnetic properties through experimental and numerical studies. The results showed that an obvious pressure drop happened when the pressure is about 400 kPa in seal cavity for MR fluid seal, but the pressure was quickly down to around 390 kPa; nevertheless, the maximum pressure of the FF seal is 200 kPa, and the seal time with leak-free is about 2.5 min, and then the value quickly goes down to zero. The maximum pressure of every pole tooth of FF seal is about 11.11 kPa. The pressure of MR fluid seal is 21.67 kPa when there is a significant decrease during pressuring, and the maximum pressure of every pole tooth of MR fluid seal is 41.37 kPa. At last, the relationship of the sealing pressure of MR fluid seal with the time was derived.