An investigation into the non-linear dynamics of an unbalanced flexible rotor running in an unsupported squeeze-film damper bearing

2003 ◽  
Vol 217 (8) ◽  
pp. 955-971 ◽  
Author(s):  
P Bonello ◽  
M J Brennan ◽  
R Holmes
Keyword(s):  
Harmonic Balance Method ◽  
Housing System ◽  
Squeeze Film ◽  
Flexible Rotor ◽  
Linear Dynamics ◽  
Squeeze Film Damper ◽  
Analytical Technique ◽  
Synchronous Motion ◽  
Non Linear ◽  
The Stability

The non-linear dynamics of a multimodal flexible rotor running in an unsupported squeeze-film damper (SFD) bearing are investigated analytically and experimentally. The main aim is to assess the ability to predict and explain the non-linear performance using an integrated analytical technique and a standard model for the SFD. A fast harmonic balance method that uses receptance functions is used to determine periodic solutions. A modal-based approach is used for the analysis of the stability and bifurcation of these solutions, as well as the analysis of aperiodic motion. Non-synchronous motion with combination frequencies and subharmonic motions are correctly predicted. It is also shown that such an SFD introduces subcritical superharmonic resonance when it is apparently inactive. It is concluded that, despite the economy in design, the benefits of using an unsupported SFD in a flexible rotor-rigid bearing housing system are dubious.

A theoretical and experimental investigation into the vibration response of a flexible rotor and squeeze-film damper assembly

2001 ◽  
Vol 215 (10) ◽  
pp. 1251-1269 ◽  
Author(s):  
C-C Siew ◽  
M Hill ◽  
R Holmes ◽  
M Brennan
Keyword(s):  
Harmonic Balance ◽  
Three Dimensional ◽  
Harmonic Balance Method ◽  
Vibration Response ◽  
Mode Shapes ◽  
Squeeze Film ◽  
Flexible Rotor ◽  
Linear Vibration ◽  
Squeeze Film Damper ◽  
Good Agreement

This paper presents two efficient methods to calculate the unbalance vibration response of a flexible rotor provided with a squeeze-film damper (SFD) with retainer springs. Both methods are iterative and combine the harmonic balance and receptance approaches. The first method, called the modified iteration method (MIM), is suitable for predicting the three-dimensional mode shapes of a concentric SFD-rotor system. The second method, called the modified harmonic balance method (MHBM), is developed to calculate the non-linear vibration response of a flexible shaft provided with either a concentric or eccentric SFD. The system is also investigated experimentally under different conditions. The predictions computed by these methods are compared with experimental measurements and reasonably good agreement is obtained.

Forced Response of a Flexible Rotor With Squeeze Film Damper Under Parametric Change

2013 ◽  
Author(s):  
Feng He ◽  
Paul E. Allaire ◽  
Saeid Dousti ◽  
Alexandrina Untaroiu
Keyword(s):  
Harmonic Balance Method ◽  
Forced Response ◽  
Squeeze Film ◽  
Flexible Rotor ◽  
Fluid Inertia ◽  
Inertia Effects ◽  
Squeeze Film Damper ◽  
Vibrational Response ◽  
Parametric Change ◽  
Gyroscopic Effects

Squeeze film dampers play an important role in the dynamics of modern turbomachinery by improving vibrational response and stability. The present paper develops an effective tool for evaluating the forced response of these systems under parametric changes. A flexible rotor with multiple masses supported on a squeeze film damper at one end is investigated. The forced response of this asymmetrically supported system is obtained using the harmonic balance method with a predictor-corrector procedure. This response is examined with various parameters including unbalance forces with and without fluid inertia effects, unidirectional loads, stiffness of centering spring of the damper and the gyroscopic effects of the disks. The developed tool predicts the nonlinear jump phenomenon of the damper with large unbalance forces, indicates the present of multiple harmonics within the response with high damper eccentricity and shows the insensitivity of the damper to surrounding gyroscopic variation.

A Study of the Influence of Static Eccentricity and Unbalance on Cavitation Effects in a Squeeze Film Damped Flexible Rotor

2002 ◽  
Author(s):  
Philip Bonello ◽  
Michael J. Brennan ◽  
Roy Holmes
Keyword(s):  
Dynamic Systems ◽  
Harmonic Balance ◽  
Harmonic Balance Method ◽  
Squeeze Film ◽  
Flexible Rotor ◽  
Test Rig ◽  
Squeeze Film Damper ◽  
Static Eccentricity ◽  
Rotor Dynamic ◽  
Rigid Rotors

The study of eccentric squeeze film damped rotor dynamic systems has largely concentrated on rigid rotors. In this paper, a newly developed receptance harmonic balance method is used to efficiently analyze a squeeze film damped flexible rotor test rig. The aim of the study is to investigate the influence of damper static eccentricity and unbalance level on cavitation and its resulting effect on the vibration level. By comparing predictions for the rotor vibration levels obtained respectively with, and without, lower pressure limits for the eccentric squeeze film damper model, it is demonstrated that cavitation is promoted by increasing static eccentricity and/or unbalance level. This, in turn, is found to have a profound effect on the predictions for the critical vibration levels, which such dampers are designed to attenuate. The reported findings are backed by experimental evidence from the test rig.

A Study of the Nonlinear Interaction Between an Eccentric Squeeze Film Damper and an Unbalanced Flexible Rotor

2004 ◽  
Vol 126 (4) ◽  
pp. 855-866 ◽  
Author(s):  
Philip Bonello ◽  
Michael J. Brennan ◽  
Roy Holmes
Keyword(s):  
Periodic Solutions ◽  
Nonlinear Interaction ◽  
Harmonic Balance ◽  
Linear Part ◽  
Harmonic Balance Method ◽  
Squeeze Film ◽  
Flexible Rotor ◽  
Test Rig ◽  
Squeeze Film Damper ◽  
Static Eccentricity

In this paper, the nonlinear interaction between an eccentric squeeze film damper and an unbalanced flexible rotor is investigated, paying particular attention to the effect of cavitation in the damper. A harmonic balance method that uses the receptance functions of the rotating linear part of the system to determine periodic solutions to the nonlinear problem is used to predict vibration levels in a test rig. By comparing predictions obtained respectively with, and without, lower pressure limits for the squeeze film damper model, it is concluded that cavitation is promoted by increasing static eccentricity and/or unbalance level. This, in turn, is found to have a profound effect on the predictions for the critical vibration levels, which such dampers are designed to attenuate. Experimental results are presented to support the findings.

Stability and Bifurcation of a Rotor-Fluid Film Bearing System With Squeeze Film Damper

1998 ◽  
Vol 120 (4) ◽  
pp. 1003-1006 ◽  
Author(s):  
Jiazhong Zhang ◽  
Qingyu Xu ◽  
Tiesheng Zheng
Keyword(s):  
Bifurcation Theory ◽  
Shooting Method ◽  
Period Doubling ◽  
Squeeze Film ◽  
Flexible Rotor ◽  
Squeeze Film Damper ◽  
Dynamical Behaviors ◽  
Unbalanced Rotor ◽  
The Stability ◽  
Bearing System

The dynamical behaviors of a flexible rotor supported by two plain cylindrical bearings surrounded by squeeze film damper are investigated. In this study, the Hopf bifurcation theory is used to investigate the stability of the equilibrium position of the system, then the unbalanced rotor response is determined by the shooting method and the stability of these solution is examined using the Floquet transition matrix method. It is shown that the quasi-periodic motion and period-doubling motion may be excited by the rotor unbalance.

The Vibration Isolating Properties of Uncentralized Squeeze-Film Damper Bearings Supporting a Flexible Rotor

1981 ◽  
Vol 103 (4) ◽  
pp. 781-787 ◽  
Author(s):  
R. A. Cookson ◽  
S. S. Kossa
Keyword(s):  
Analytical Approach ◽  
Effective Means ◽  
Squeeze Film ◽  
Dimensional System ◽  
Flexible Rotor ◽  
Response Curves ◽  
Squeeze Film Damper ◽  
Analytical Technique ◽  
System Parameters ◽  
Bearing System

The ability of an uncentralized squeeze-film damper bearing to inhibit the effects of vibration in a flexible rotor-bearing system, has been assessed in terms of non-dimensional system parameters. This analytical approach has shown that a correctly designed squeeze-film damper bearing is a very effective means of reducing both the amplitude of motion of the rotor and the force transmitted to the bearing support structure. However, the analysis has also indicated that a poorly designed squeeze-film damper bearing can produce amplitudes and forces greater than those which would arise if the bearing support remained rigid. An experimental programme has supported the validity of the above analytical technique by showing that the measured motion orbits of the journal and disk centers as the rotor passes through the critical speed, are very similar to those predicted theoretically. Also, the response curves for specific groups of system parameters show very similar trends in practice, to those which result from the analytical approach. Some indication of the ability of a squeeze-film damper bearing to reduce the effect of much greater unbalance than normal is also reported.

Stability and Bifurcation of Unbalanced Response of a Squeeze Film Damped Flexible Rotor

1994 ◽  
Vol 116 (2) ◽  
pp. 361-368 ◽  
Author(s):  
J. Y. Zhao ◽  
I. W. Linnett ◽  
L. J. McLean
Keyword(s):  
Power Spectra ◽  
Squeeze Film ◽  
Integration Scheme ◽  
Flexible Rotor ◽  
Jump Phenomenon ◽  
Stability And Bifurcation ◽  
Trigonometric Collocation ◽  
Numerical Integration Scheme ◽  
The Stability ◽  
Nonsynchronous Vibrations

The stability and bifurcation of the unbalance response of a squeeze film damper-mounted flexible rotor are investigated based on the assumption of an incompressible lubricant together with the short bearing approximation and the “π” film cavitation model. The unbalanced rotor response is determined by the trigonometric collocation method and the stability of these solutions is then investigated using the Floquet transition matrix method. Numerical examples are given for both concentric and eccentric damper operations. Jump phenomenon, subharmonic, and quasi-periodic vibrations are predicted for a range of bearing and unbalance parameters. The predicted jump phenomenon, subharmonic and quasi-periodic vibrations are further examined by using a numerical integration scheme to predict damper trajectories, calculate Poincare´ maps and power spectra. It is concluded that the introduction of unpressurized squeeze film dampers may promote undesirable nonsynchronous vibrations.

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