Magnetorheological seal: A review

Magnetorheological fluid (MRF) sealing technology has gained more and more attention in civil engineering, safety engineering, manufacturing, life science, aviation and so on, owing to its great pressure bearing capacity due to the viscous stress and controllable yield stress of MRF under external magnetic field. Even if overpressure occurs, magnetorheological seal (MRS) can restore the serviceability automatically with the help of magnetic field when pressure difference drops back. To have a deep understanding of magnetorheological sealing technique, the paper begins with an introduction of the basic features of MRF and relevant applications of MRS. Then several basic design issues of MRS structure are introduced. Furthermore, main factors influencing MRS performance are discussed on how to increase the pressure drop of MRS structure. In the end, modeling techniques of MRS structure are provided according to Bingham plastic model, Bi-viscous model, Herschel-Bulkley model and Herschel-Bulkley model with preyield viscosity, respectively, for calculating yield stress of MRF and pressure drop of MRS structure. Hopefully, this review can be regarded as a useful complement to other reviews on MRF technology and applications.