The cause for aero-induced exciting forces, as noted above, is the swirl or the tangentialring with blade-and reduce the swirl velocity. This device improves the stability of the rotor-bearing back-to-back comDIGEST, Vol. 12, No. 2, pp. 375-383 2. Ruddy, A.V., and Summers-Smith, D., 1980, Systems, pp. 213-Seminar, Quebec City, pp. 6.23-6.32, October 21-23 6. Memmott, E. A., 2000, rical Estimation of a Load Related Cross-Coupled Stiffness and The LateralDynamics Seminar, Halifax, pp. 9-20, April 26-28. 7. Wachel, J. C. and von Nimitz, W.Petroleum Technology, pp. 2252-2260, Nov. 8. Alford, J. S., 1965, "Protecting Turbomachinery from Self-Excited Whirl," ASME Journal of Engineering for Power, Vol. 38, pp. 333-344 9. Memmott, E. A., 1992, "Stability of Centrifugal Compressors byInternational Conference on Vibrations in Rotating Machinery, Bath, pp. 99-106, September 7-10. 10. Marshall, D. F., Hustak, J. F., and Memmott, E. A., 1993,Application of Damper Bearings, Tilting Pad Seals, and Shunt Holes," NJIT-ASME-HI-November 10-12. 11. Memmott, E. A., 1994, "Stability of a High Pressure Centrifugal13th Machinery Dynamics Seminar, Toronto, Canada, pp. 211-233, September 12-13. 12. Engineering, Texas A&M University, College Station, Texas, September 17-19. 13. ASME Paper DETC99/VIB-8294, Las Vegas, Nevada, September 12-15 Short Course atInternational Symposium on Transport Phenomena and Rotating Machinery, ISROMAC-8, Vol. II, Honolulu, Hawaii, pp. 1124-1132, March 26-30 15. Ramesh, K, 2002, "A State-of-the-art Rotor Dynamic Analysis Program," Proceedings of the 9th InternationalHawaii, February 10-14 16. Moore, J.J, Walker, S.T., Kuzdzal, M.J., 2002,-Load, Full-Pressure Testing of a 6000 PSE Re-InjectioReInjection Centrifugal Compressor During Full-Load, Full-Pressure Testing UsingIllinois, DETC2003/VIB48458, September 2-6 Short Course at GMRC 2005 Page 23 of 23。