0
TECHNICAL PAPERS

Identification of Force Coefficients in a Squeeze Film Damper With a Mechanical End Seal—Centered Circular Orbit Tests

[+] Author and Article Information
Luis San Andrés

Mechanical Engineering Department, Texas A&M University, College Station, TX 77843lsanandres@mengr.tamu.edu

Adolfo Delgado

Mechanical Engineering Department, Texas A&M University, College Station, TX 77843adelgam@tamu.edu

This deficiency does not just occur in SFDs but also in liquid annular seals and hydrostatic bearings as the extensive literature attests.

Loads of lower magnitude could not induce motion in the test system. At times for the lowest load, stick–slip occurred over certain frequency ranges; see Ref. 19 for details.

While the test system was operated in a linear regime, a single frequency motion response ensued for sufficiently large excitation loads that forced the bearing to move well beyond a stick–slip regime in the mechanical seal.

The two procedures, namely conservation of momentum and energy dissipated=external work, render exactly the same damping coefficients.

J. Tribol 129(3), 660-668 (Feb 08, 2007) (9 pages) doi:10.1115/1.2736708 History: Received March 07, 2006; Revised February 08, 2007

The damping capability of squeeze film dampers (SFDs) relies on adequate end sealing to prevent air ingestion and entrapment. The paper presents the parameter identification procedure and force coefficients of a test SFD featuring a mechanical seal that effectively eliminates lubricant side leakage. The test damper reproduces an aircraft application intended to contain the lubricant in the film lands for extended periods of time. The test damper journal is 2.54cm in length and 12.7cm in diameter, with a nominal clearance of 0.127mm. The SFD feed end is flooded with oil, while the discharge end contains a recirculation groove and four orifice ports. In a companion paper (San Andrés and Delgado, 2006, ASME J. Eng. Gas Turbines Power, 119, to be published) single frequency–unidirectional load excitation tests were conducted, without and with lubricant in the squeeze film lands, to determine the seal dry-friction force and viscous damping force coefficients. Presently, tests with single frequency excitation loads rendering circular centered orbits excitations are conducted to identify the SFD force coefficients. The identified parameters include the overall system damping and the individual contributions from the squeeze film, dry friction and structural damping. The identified system damping coefficients are frequency and motion amplitude dependent due to the dry friction interaction at the mechanical seal interface. Identified squeeze film force coefficients, damping, and added mass, are in good agreement with predictions based on the full film, short length damper model.

FIGURES IN THIS ARTICLE
<>
Copyright © 2007 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Assembly cut view of SFD with mechanical seal

Grahic Jump Location
Figure 2

Test rig for dynamic force measurements and flow visualization in a sealed end SFD

Grahic Jump Location
Figure 3

Work exerted by input force (=dissipated energy) estimated from combined damping model (dry SFD, end seal in place)

Grahic Jump Location
Figure 4

Experimental equivalent viscous damping (dry friction+residual) versus excitation frequency (circular centered orbits-dry SFD, end seal in place)

Grahic Jump Location
Figure 5

Dynamic excitation load orbits for four amplitude force levels (20Hz, lubricated SFD)

Grahic Jump Location
Figure 6

Recorded circular orbits for four load amplitude levels and clearance circle (20Hz, lubricated SFD)

Grahic Jump Location
Figure 7

Real part of dynamic stiffness obtained from periodic load tests and model predictions (amplitude of motion: 50μm, Ks=823kN∕m, MD=19.2kg, circular centered orbits, lubricated SFD)

Grahic Jump Location
Figure 8

Identified system direct damping coefficient (CD) versus excitation frequency for increasing orbit radii (circular centered orbits, lubricated SFD)

Grahic Jump Location
Figure 9

Squeeze film damping coefficient (Cxx=Cyy) versus excitation frequency for increasing orbit radii (circular centered orbits, lubricated SFD)

Grahic Jump Location
Figure 10

Identified system damping coefficient (CD) versus orbit radius for increasing frequencies (excitation frequency: 20–60Hz (10Hz increments) circular centered orbits, lubricated SFD)

Grahic Jump Location
Figure 11

Squeeze film damping coefficient (Cxx=Cyy) versus orbit radius (excitation frequency: 20Hz and 60Hz, circular centered orbits, lubricated SFD)

Tables

Errata

Discussions

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