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Turbomachine Sealing and Secondary FlowsToday's computational methods enable the determination of forces in complex systems, but without field validation data, or feedback, there is a high risk of failure when the design envelope is challenged. The data of Childs and Bently and field data reported in NASA Conference Proceedings serve as sources of design information for the development of these computational codes. Over time all turbomachines degrade and instabilities often develop, requiring responsible, accurate, turbomachine diagnostics with proper decisions to prevent failures. Tam et al. (numerical) and Bently and Muszynska (analytical) models corroborate and implicate that destabilizing factors are related through increases in the fluid-force average circumferential velocity. The stability threshold can be controlled by external swirl and swirl brakes and increases in radial fluid film stiffness (e.g., hydrostatic and ambient pressures) to enhance rotor stability. Also cited are drum rotor self-excited oscillations, where the classic fix is to add a split or severed damper ring or cylindrical damper drum, and the Benkert-Wachter work that engendered swirl brake concepts. For a smooth-operating, reliable, long-lived machine, designers must pay very close attention to sealing dynamics and diagnostic methods. Correcting the seals enabled the space shuttle main engine high-pressure fuel turbopump (SSME HPFTP) to operate successfully.
Document ID
Document Type
Technical Memorandum (TM)
Hendricks, R. C.
(NASA Glenn Research Center Cleveland, OH, United States)
Tam, L. T.
(Lockheed Martin Space Systems Co. Sunnyvale, CA, United States)
Muszynska, A.
(A. M. Consulting Minden, NV, United States)
Date Acquired
September 7, 2013
Publication Date
July 1, 2004
Subject Category
Aeronautics (General)
Report/Patent Number
Meeting Information
Second International Symposium on Stability Control of Rotating Machinery(Gdansk)
Distribution Limits
Work of the US Gov. Public Use Permitted.

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