Failure of magnetic fluid seals operating in water: preliminary conclusions
The article analyses properties of magnetic fluid seals installed in rotary sealing nodes which operate in the utility water environment. Seals of this type have been examined as a possible solution to the problem with ship manoeuvring propulsion sealing. The present analysis bases on laboratory durability tests of magnetic fluid seals exposed to long-term utility water loads, at different water pressures and shaft revolutions. The basic seal durability criterion was the number of revolutions made by the sealing node shaft until the appearance of water tightness loss (leakage). It was found that the main factor leading to the wear of the seal is the relative speed of the magnetic fluid with respect to that of the utility water, and this process is heavily affected by the pressure acting on the seal. The reported test results are presented in the form of diagrams showing the seal durability (time until water tightness loss) as a function of rotational speed. The curves shown in the diagrams are regular, with two different rotational speed ranges: the high-speed range, when the tightness loss is relatively fast, and the low-speed range, with a clear tendency to prolong the seal lifetime. These diagrams were given the name of durability curves of the MF seal operating in water. The results of the performed tests suggest formal similarity between the experimental data distribution concerning tightness loss processes occurring in magnetic fluid seals operating in water environment and metal fatigue processes. The article proposes a preliminary simplified durability model to describe the examined phenomenon
- 1. Bielański J.: Description of the hydrodynamic pressure field function around the ship hull, Hydroacoustics, Vol.14, pp. 17-22, Gdynia 2011. 208
- 2. Ferrolabs, Inc. · Sterling, VA United States, http://www.ferrolabs.com/. 2010, company catalogue.
- 3. GASIAK, G., PAWLICZEK, R.: Fatigue strength of structural steel in non-symmetrical load conditions (in Polish). Zeszyty Naukowe Mechanika, Opole University of Technology, Vol. 74, pp., 25-41, Opole 2002.
- 4. Guo, C., Feng, S.: Sealing mechanism of magnetic fluids. Journal of Shanghai University (English Edition), 2006, 10(6), pp.522-525.
- 5. Liu, T., Cheng, Y., Yang, Z.: Design optimization of seal structure for sealing liquid by magnetic fluids. Journal of Magnetism and Magnetic Materials, Vol: 289, Complete, March 2005.
- 6. Matuszewski, L.: Procedure for determining durabil-ity and results of experimental tests of multi-tooth MF seals operating in water (in Polish). PB, Department of Machine Design and Technology, AGH, Cracow 2012. 211, Zeszyty Naukowe AGH
- 7. Matuszewski, L.: Final report on the research project R 00-O0017/3 entitled: Implementation prototype of elec-tric annular propulsion system equipped with magnetic bearings and sealed with magnetic fluids - structure and operating tests (in Polish).
- 8. Mitamura, Y., Arioka, S., Sakota, K., Azegami, M.: Appli-cation of a magnetic fluid sea l to rotar y blood pumps., J. Phys.: Condens. Matter 20 (2008) 204145 (5pp).
- 9. Odenbach, S: Mag netov iscous effects in mag net ic fluids, Berlin; Heidelberg; New York; Barcelona; Hong Kong; London; Milan; Paris; Tokyo: Springer, 2002, (Lecture notes in physics: N.s. M, Monographs; 71)
- 10. Odenbach, S. (Ed.): Colloidal Magnetic Fluids: Basics, Development and Application of Magnetic fluids, Lect. Notes Phys. 763 (Springer, Berlin Heidelberg 2009), DOI 10.1007/978-3-540-85387-9
- 11. Orlov, D.W., Mikhalev, Y.O., Myshkin, N.K., Podgorkov, W.W., Sizov, A.P.: Magnitnye żidkosti w mashinostroenii. Mashinostroenie, Moskva 1993.
- 12. P.P.H.U. “ENES” Pawel Zientek, Warszawa, www.mag-nesy.pl/, company catalogue.
- 13. Research project: Theoretical analysis, structure and experimental tests of seals with magnetic fluids used in sealing systems operating in water environment – in the aspect of operating condition limits; final report (in Polish), AGH, KKiEM, 2010.
- 14. Rosensweig, R.E.: Ferrohydrodynamics. Dover Publica-tions, Inc. Mineola, New York, 1997
- 15. SALWIŃSKI, J., HORAK, W., SZCZĘCH, M., KOWA-LIK, G.: Analysis of design issues concerning magnetic fluid seals working in reciprocating motion conditions (in Polish), XXVII Symposium on machinery design fundamentals: Zakopane 2007, 22-26 Sept.
- 16. Szydło, Z., Matuszewski, L.: Experimental research on effectiveness of the magnetic fluid seals for rotary shafts working in water. Polish Maritime Research, 2007, vol. 14, no. 4, pp. 53–58.
- 17. Szydło, Z., Matuszewski, L.: Ring thruster – a pre-liminary optimisation study of magnetic fluid seal and propeller. Polish Maritime Research, 2007, special issue S1,pp. 71–74.
- 18. Szydło, Z., Matuszewski, L.: The application of magnetic fluids in sealing nodes designed for operation in difficult conditions and in machines used in sea environment. Polish Maritime Research, 2008, vol. 15, no. 3, pp. 49–58.