Gas turbine aircraft engine manufacturers push for simple squeeze film damper (SFD) designs, short in length, yet able to provide enough damping to ameliorate rotor vibrations. SFDs employ orifices to feed lubricant directly into the film land or into a deep groove. The holes, acting as pressure sources (or sinks), both disrupt the film land continuity and reduce the generation of squeeze film dynamic pressure. Overly simple predictive formulations disregard the feedholes and deliver damping (C) and inertia (M) force coefficients not in agreement with experimental findings. Presently, to bridge the gap between simple theory and practice, the paper presents measurements of the dynamic forced response of an idealized SFD that disposes of the feedholes altogether. The short-length SFD, whose diameter D = 127 mm, has one end submerged (flooded) within a lubricant bath and the other end exposed to ambient. ISO VG 2 lubricant flows by gravity through the film land of length L = 25.4 mm and clearance c = 0.122 mm. From dynamic load tests over excitation frequency range 10–250 Hz, experimental damping coefficients (CXX, CYY) from the flooded damper agree well with predictions from the classical open ends model with a full film for small amplitude whirl motions (r/c ≪ 1), centered and off-centered. Air ingestion inevitably occurs for large amplitude motions (r/c > 0.4), thus exacerbating the difference between predictions and tests results. For reference, identical tests were conducted with a practical SFD supplied with lubricant (Pin = 0.4 bar) via three orifice feedholes, 120 deg apart at the film land midplane. A comparison of test results shows as expected that, for small amplitude (r/c ∼ 0.05) orbits, the flooded damper generates on average 30% more damping than the practical configuration as the latter's feedholes distort the generation of pressure. For large amplitude motions (r/c > 0.4), however, the flooded damper provides slightly lesser damping and inertia coefficients than the SFD with feedholes whose pressurized lubricant delivery alleviates air ingestion in the film land. The often invoked open ends SFD classical model is not accurate for the practical engineered design of an apparently simple mechanical element.

References

References
1.
San Andrés
,
L.
,
2012
, “
Modern Lubrication Theory, Squeeze Film Damper: Operation, Models and Technical Issues, Notes 13
,”
Texas A&M University Digital Libraries
, College Station, TX.http://rotorlab.tamu.edu/me626/Notes_pdf/Notes13%20Squeeze%20Film%20Dampers.pdf
2.
Vance
,
J. M.
,
1988
,
Rotordynamics of Turbomachinery
,
Wiley
,
Hoboken, NJ
, Chap. 6.
3.
Harnoy
,
A.
,
2002
,
Bearing Design in Machinery: Engineering Tribology and Lubrication
,
CRC Press
,
Boca Raton, FL
, Chap. 18.
4.
Zeidan
,
F.
,
San Andrés
,
L.
, and
Vance
,
J.
,
1996
, “
Design and Application of Squeeze Film Dampers in Rotating Machinery
,”
25th Turbomachinery Symposium
, Houston, TX, Sept. 16–19, pp.
169
188
.http://turbolab.tamu.edu/proc/turboproc/T25/T25169-188.pdf
5.
San Andrés
,
L.
, and
Jeung
,
S.-H.
,
2015
, “
Experimental Performance of an Open Ends, Centrally Grooved, Squeeze Film Damper Operating With Large Amplitude Orbital Motions
,”
ASME J. Eng. Gas Turbines Power
,
137
(
3
), p.
032508
.
6.
Jeung
,
S.-H.
,
San Andrés
,
L.
, and
Bradley
,
G.
,
2015
, “
Forced Coefficients for a Short Length, Open-Ends Squeeze Film Damper With End Grooves: Experiments and Predictions
,”
ASME J. Eng. Gas Turbines Power
,
138
(
2
), p.
022501
.
7.
San Andrés
,
L.
, and
Jeung
,
S.-H.
,
2016
, “
Orbit-Model Force Coefficients for Fluid Film Bearings: A Step Beyond Linearization
,”
ASME J. Eng. Gas Turbines Power
,
138
(
2
), p.
022502
.
8.
San Andrés
,
L.
,
Jeung
,
S.-H.
,
Den
,
S.
, and
Savela
,
G.
,
2016
, “
Squeeze Film Damper: An Experimental Appraisal of Their Dynamic Performance
,”
Asia Turbomachinery and Pump Symposium
(
ATPS
), Singapore, Feb. 22–26, pp. 1–23.http://rotorlab.tamu.edu/tribgroup/2016%20TRC%20San%20Andres/2016%20ATPS%20SFD%20paper.pdf
9.
Den
,
S.
,
2015
, “
Analysis of Force Coefficients and Dynamic Pressures for Short-Length (L/D = 0.2) Open-Ends Squeeze Film Dampers
,” M.S. thesis, Texas A&M University, College Station, TX.
10.
San Andrés
,
L.
,
2012
, “
Modern Lubrication Theory, Liquid Cavitation in Fluid Film Bearings, Notes 6
,”
Texas A&M University Digital Libraries
, College Station, TX.http://rotorlab.tamu.edu/me626/Notes_pdf/Notes06%20Liquid%20cavitation%20model.pdf
11.
Diaz
,
S.
, and
San Andrés
,
L.
,
2001
, “
A Model for Squeeze Film Dampers Operating With Air Entrainment and Validation With Experiments
,”
ASME J. Tribol.
,
123
(
1
), pp.
125
133
.
12.
Diaz
,
S.
, and
San Andrés
,
L.
,
2001
, “
Air Entrainment Versus Lubricant Vaporization in Squeeze Film Dampers: An Experimental Assessment of Their Fundamental Differences
,”
ASME J. Eng. Gas Turbines Power
,
123
(
4
), pp.
871
877
.
13.
Gehannin
,
J.
,
Arghir
,
M.
, and
Bonneau
,
O.
,
2015
, “
A Volume of Fluid Method for Air Ingestion in Squeeze Film Dampers
,”
Tribol. Trans.
,
59
(
2
), pp.
208
218
.
14.
Adiletta
,
G.
, and
Della Pietra
,
L.
,
2006
, “
Experimental Study of a Squeeze Film Damper With Eccentric Circular Orbits
,”
ASME J. Tribol.
,
128
(
2
), pp.
365
377
.
15.
Pan
,
C. H. T.
, and
Tonessen
,
J.
,
1978
, “
Eccentric Operation of Squeeze-Film Damper
,”
J. Lubr. Technol.
,
100
(
3
), pp.
369
377
.
16.
Fritzen
,
C. P.
,
1986
, “
Identification of Mass, Damping, and Stiffness Matrices of Mechanical System
,”
J. Vib., Acoust., Stress, and Reliab.
,
108
(
1
), pp.
9
16
.
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