Affiliations: [a] School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044, China | [b] China University of Labor Relations, Beijing 100048, China | [c] State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
Correspondence:
[*]
Corresponding author: Decai Li, School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044, China. E-mail: dcli@bjtu.edu.cn.
Abstract: When applied in the field of sealing liquids, sealing performance of ferrofluids degrades due to the surface instability induced by direct contact and relative motion between ferrofluids and the sealed liquids. Consequently, it can not be widely applied. In order to improve the performance of ferrofluid seal for liquid medium, an improved ferrofluid seal adding gas isolation device was developed to prevent direct contact between ferrofluids and the sealed liquids. The critical pressure of the improved ferrofluid seal was derived theoretically. Magnetic field intensity in the seal gap and fluid dynamics of the sealed liquids and compressed gas were simulated. A special designed experiment platform was built on which the critical pressure and seal life of the original structure and improved structure were measured and compared. From the theory and experiment results, it can be seen that sealing performance has been significantly improved with the adoption of the improved ferrofluid seal and the sealing problem has been solved by converting sealing liquids to sealing gas. The results of this study give a guidance for solution of sealing liquids with ferrofluids.
Keywords: Ferrofluid seal, critical pressure, seal life, gas isolation
