RESEARCH PAPERS: Gas Turbines: Structures and Dynamics

Experimentally Determined Rotor Power Losses in Homopolar and Heteropolar Magnetic Bearings

[+] Author and Article Information
M. E. F. Kasarda

Department of Mechanical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0238

P. E. Allaire, P. M. Norris, E. H. Maslen

Mechanical, Aerospace, and Nuclear Engineering Department, University of Virginia, Charlottesville, VA 22901

C. Mastrangelo

Department of Systems Engineering, University of Virginia, Charlottesville, VA 22901

J. Eng. Gas Turbines Power 121(4), 697-702 (Oct 01, 1999) (6 pages) doi:10.1115/1.2818529 History: Received March 16, 1998; Revised June 23, 1999; Online December 03, 2007


The identification of parameters that dictate the magnitude of rotor power losses in radial magnetic bearings is very important for many applications. Low loss performance of magnetic bearings in aerospace equipment such as jet engines and flywheel energy storage systems is especially critical. Two basic magnetic bearing designs are employed in industrial practice today: the homopolar design, where the flux paths are of a mixed radial/axial orientation, and the heteropolar design, where the flux paths are primarily radial in nature. The stator geometry and flux path of a specific bearing can have a significant effect on the rotor losses. This paper describes the detailed measurement of rotor losses for experimentally comparable homopolar and heteropolar designs. The two test bearing configurations are identical except for geometric features that determine the direction of the flux path. Both test bearing designs have the same air gap length, tip clearance ratio, surface area under the poles, and bias flux levels. An experimental test apparatus was used where run down tests were performed on a test rotor with both bearing designs to measure power losses. Numerous test runs where made for each bearing configuration by running multiple levels of flux density. The components of the overall measured power loss, due to hysteresis, eddy currents, and windage, were determined based on theoretical expressions for power loss. It was found that the homopolar bearing had significantly lower power losses than the heteropolar bearing.

Copyright © 1999 by The American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.





Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In