Modeling Ferrofluid Flow in an Annular Gap Moving with Reciprocating Shaft

Y. He[1], R. Nilssen[1]
[1]Department of Electric Power Engineering, Norwegian University of Science and Technology, Trondheim, Norway

Ferrofluids have been successfully used in the seals for rotary shafts, but few studies focus on the reciprocating motion seals. Since the completely different operational regimes, previous experiences on the rotary motions could not be directly applied on the cases for reciprocating shafts. In this study, we present a simplified model to describe the process that a shaft linearly moving in a cylinder housing, which coated with a layer of ferrofluids. The results show that the external magnetic field increases the load capacity of ferrofluid seal when the frequency of shaft lower than a critical value. However, considerable inertia force due to high frequency reciprocating motion weakened the function of magnetic fore, and caused the loss of ferrofluids.