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Actively controlled shaft seals for aerospace applicationsThis study experimentally investigates an actively controlled mechanical seal for aerospace applications. The seal of interest is a gas seal, which is considerably more compact than previous actively controlled mechanical seals that were developed for industrial use. In a mechanical seal, the radial convergence of the seal interface has a primary effect on the film thickness. Active control of the film thickness is established by controlling the radial convergence of the seal interface with piezoelectric actuator. An actively controlled mechanical seal was initially designed and evaluated using a mathematical model. Based on these results, a seal was fabricated and tested under laboratory conditions. The seal was tested with both helium and air, at rotational speeds up to 3770 rad/sec, and at sealed pressures as high as 1.48 x 10(exp 6) Pa. The seal was operated with both manual control and with a closed-loop control system that used either the leakage rate or face temperature as the feedback. The output of the controller was the voltage applied to the piezoelectric actuator. The seal operated successfully for both short term tests (less than one hour) and for longer term tests (four hours) with a closed-loop control system. The leakage rates were typically 5-15 slm (standard liters per minute), and the face temperatures were generally maintained below 100 C. When leakage rate was used as the feedback signal, the setpoint leakage rate was typically maintained within 1 slm. However, larger deviations occurred during sudden changes in sealed pressure. When face temperature was used as the feedback signal, the setpoint face temperature was generally maintained within 3 C, with larger deviations occurring when the sealed pressure changed suddenly.
Document ID
19950017798
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Salant, Richard F. (Georgia Inst. of Tech. Atlanta, GA, United States)
Date Acquired
September 6, 2013
Publication Date
December 31, 1994
Subject Category
Mechanical Engineering
Report/Patent Number
NAS 1.26:198035
NASA-CR-198035
Accession Number
95N24218
Funding Number(s)
CONTRACT_GRANT: NAG3-974
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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