This paper summarizes the development of hybrid squeeze film dampers (HSFDs) for active control of rotor vibrations. Previously, it was shown both theoretically and experimentally that HSFDs can be used for controlling rotor vibrations (El-Shafei, 1993). This is done by controlling the flow in a squeeze film damper through movable end seals, thus achieving the ability to change the damper from a short damper to a long damper and vice versa. However, the control of the HSFD was manual. In this paper, an automatically controlled circuit is developed for the HSFD, incorporating a pressure control servovalve for controlling the pressure in the sealing chambers. A complete mathematical model of this open-loop system is developed and is implemented on a digital computer. The transient behavior of the system, including the sealing ring dynamics, illustrates that the open-loop system exhibits well-behaved, stable, and fast response. In addition it is shown that the HSFD can achieve any amount of damping between the short and long damper modes through the accurate positioning of the sealing rings. The simulation results illustrate that the automatically controlled HSFD can be a very useful device for the active control of rotors. A closed-loop control strategy with feedback on rotor speed is also investigated both from the points of view of steady state and transient behaviors. It is shown that this closed-loop strategy results in a much improved behavior of the rotor system.

Issue Section:
Gas Turbines: Structures and Dynamics
Topics:
Bearings, Control modeling, Rotors, Dampers, Sealing (Process), Open loop systems, Rotor vibration, Transients (Dynamics), Circuits, Computers, Damping, Dynamics (Mechanics), Feedback, Flow (Dynamics), Pressure, Pressure control, Simulation results, Steady state
1.
Adams, M. L., and Zahloul, H., 1987, “Attenuation of Rotor Vibration Using Controlled-Pressure Hydrostatic Squeeze-Film Dampers,” presented at the Eleventh Biennial ASME Vibrations Conference, Boston, MA, Sept.
2.
Akin, J. T., 1990, Pratt & Whitney, private communication.
3.
Bradfield, C. D., Roberts, J. B., and Karunendiran, S., 1989, “A Programmable Electromagnetic Bearing for Vibration Control of a Flexible Shaft,” in: Rotating Machinery Dynamics, T. S. Sankar et. al., eds., ASME DE-Vol. 18–1, pp. 335–343.
4.
Burrows, C. R., Sahinkaya, M. N., and Turkay, O. S., 1983, “An Adaptive Squeeze-Film Bearing,” ASME Paper No. 83-Lub-23.
5.
El-Shafei
A.
,
1990
, “
Unbalance Response of a Jeffcott Rotor Incorporating Short Squeeze Film Dampers
,”
ASME JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER
, Vol.
112
, pp.
445
–
453
.
6.
El-Shafei
A.
,
1991
a, “
Unbalance Response of a Jeffcott Rotor Incorporating Long Squeeze Film Dampers
,”
ASME Journal of Vibration and Acoustics
, Vol.
113
, pp.
85
–
94
.
7.
El-Shafei, A., 1991b, “Hybrid Squeeze Film Damper for Active Control of Rotors,” U.S. Patent number 5,058,452, Oct.
8.
El-Shafei, A., and Crandall, S. H., 1991, “Fluid Inertia Forces in Squeeze Film Dampers,” Rotating Machinery and Vehicle Dynamics, T. C. Huang et al., eds., ASME DE-Vol. 35, pp. 219–228.
9.
El-Shafei
A.
,
1993
, “
Experimental and Analytical Investigation of Hybrid Squeeze Film Dampers
,”
ASME JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER
, Vol.
115
, pp.
353
–
359
.
10.
El-Shafei, A., El-Hakim, M., and Hathout, J. P., 1993, “Control of Rotor Vibrations Using Hybrid Squeeze Film Dampers,” Report MDP-EOARD-1/93, Cairo University, Egypt.
11.
El-Shafei
A.
, and
Eranki
R. V.
,
1994
, “
Dynamic Analysis of Squeeze Film Damper Supported Rotors Using Equivalent Linearization
,”
ASME JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER
, Vol.
116
, pp.
682
–
691
.
12.
Gunter
E. J.
,
Barrett
L. E.
, and
Allaire
P. E.
,
1977
, “
Design of Nonlinear Squeeze Film Dampers for Aircraft Engines
,”
ASME Journal of Lubrication Technology
, Vol.
99
, pp.
57
–
64
.
13.
Holmes, R., and Dogan, M., 1985, “The Performance of a Sealed Squeeze-Film Bearing in a Flexible Support Structure,” Proc. IMechE, Vol. 199, No. C1.
14.
Mu
C.
,
Darling
J.
, and
Burrows
C. R.
,
1991
, “
An Appraisal of a Proposed Active Squeeze Film Damper
,”
ASME Journal of Tribology
, Vol.
113
, pp.
750
–
754
.
15.
Nonami, K., DiRusso, E., and Fleming, D. P., 1989, “Active Vibration Control for Flexible Rotor by Optimal Direct-Output Feedback Control,” in:Rotating Machinery Dynamics, T. S. Sankar et al., eds., ASME DE-Vol. 18–1, pp. 327–334.
16.
Palazzolo, A. B., Lin, R. R., Kascak, A. F., Montague, J., and Alexander, R. M., 1989, “Test and Theory for Piezoelectric Actuator—Active Vibration Control of Rotating Machinery,” in: Rotating Machinery Dynamics, T. S. Sankar et al., eds., ASME DE-Vol. 18–1, pp. 367–374.
17.
Schweitzer, G., and Ulbrich, H., 1980, “Magnetic Bearings—A Novel Type of Suspension,” Proceedings of the Second International Conference on Vibrations in Rotating Machinery, I. Mech. E., pp. 151–156.
18.
SIMNON, 1990, User’s Guide for MS-DOS Computers, Version 3.0, SSPA systems.
19.
Thayer, W. J., 1965, “Transfer Functions for Moog Servovalves,” Moog Technical Bulletin 103.
20.
Trumpler, P. R., 1966, Design of Film Bearings, MacMillan, New York.
21.
White, D. C., 1972, “The Dynamics of a Rigid Rotor Supported on Squeeze Film Bearings,” Conference on Vibrations in Rotating Machinery, Proc. IMechE, pp. 213–229.
This content is only available via PDF.
Copyright © 1995
 by The American Society of Mechanical Engineers
You do not currently have access to this content.