NDLI: Damping and Inertia Coefficients for Two Open Ends Squeeze Film Dampers With a Central Groove: Measurements and Predictions

Content Provider	The American Society of Mechanical Engineers (ASME) Digital Collection
Author	Andrés, Luis San
Copyright Year	2012
Abstract	Aircraft engine rotors are particularly sensitive to rotor imbalance and sudden maneuver loads since they are always supported on rolling element bearings with little damping. Most engines incorporate Squeeze Film Dampers (SFDs) as means to dissipate mechanical energy from rotor vibrations and to ensure system stability. The paper quantifies experimentally the forced performance of a SFD comprising two parallel film lands separated by a deep central groove. Tests are conducted on two open ends SFDs, both with diameter D = 127 mm and nominal radial clearance c = 0.127 mm. One damper has film lands with length L = 12.7 mm (short length), while the other has 25.4 mm land lengths. The central groove has width L and depth 3/4 L. A light viscosity lubricant flows into the central groove via three orifices, 120° apart, and then through the film lands to finally exit to ambient. In operation, a static loader pulls the bearing to various eccentric positions and electromagnetic shakers excite the test system with periodic loads to generate whirl orbits of specific amplitudes. A frequency domain method identifies the SFD damping and inertia force coefficients. The long damper generates six times more damping and ∼three times more added mass than the short length damper. The damping coefficients are sensitive to the static eccentricity (up to ∼0.5c) while showing lesser dependency on the amplitude of whirl motion (up to 0.2c). On the other hand, inertia coefficients increase mildly with static eccentricity and decrease as the amplitude of whirl motion increases. Cross-coupled force coefficients are insignificant for all imposed operating conditions on either damper. Large dynamic pressures recorded in the central groove demonstrate the groove does not isolate the adjacent squeeze film lands but contributes to the amplification of the film lands’ reaction forces. Predictions from a novel SFD model that includes flow interactions in the central groove and feed orifices agree well with the test force coefficients for both dampers. The test data and predictions advance current knowledge and demonstrate SFD forced performance is tied to the lubricant feed arrangement.
Sponsorship	International Gas Turbine Institute
Starting Page	769
Ending Page	778
Page Count	10
File Format	PDF
ISBN	9780791844731
DOI	10.1115/GT2012-68212
Volume Number	Volume 7: Structures and Dynamics, Parts A and B
Conference Proceedings	ASME Turbo Expo 2012: Turbine Technical Conference and Exposition
Language	English
Publisher Date	2012-06-11
Publisher Place	Copenhagen, Denmark
Access Restriction	Subscribed
Subject Keyword	Damping Viscosity Whirls Inertia (mechanics) Stability Dampers Lubricants Bearings Rotors Clearances (engineering) Aircraft engines Flow (dynamics) Stress Engines Rotor vibration Orifices Rolling bearings
Content Type	Text
Resource Type	Article

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