Iterative Determination of Squeeze Film Damper Eccentricity for Flexible Rotor Systems

1982 ◽  
Vol 104 (2) ◽  
pp. 334-338 ◽  
Author(s):  
L. M. Greenhill ◽  
H. D. Nelson
Keyword(s):  
System Analysis ◽  
Squeeze Film ◽  
Flexible Rotor ◽  
Rotor Systems ◽  
Root Finding ◽  
Unbalance Response ◽  
Rotor Bearing ◽  
Single Mass ◽  
Stiffness And Damping ◽  
Film Stiffness

A method is presented to determine the eccentricity of multiple squeeze film dampers used in multishaft rotor bearing unbalance response analyses. The procedure is iterative and is based upon the secant root finding algorithm. Unbalance response is calculated using the iteratively determined eccentricity in closed form expressions of squeeze film stiffness and damping coefficients, for either long or short bearing theory. Circular centered synchronous operation is assumed. The method is demonstrated by determining the response of a single mass centrally preloaded rotor, a multimass flexible rotor supported by two squeeze films, and a multishaft flexible rotor system employing three squeeze film supports. The results obtained in the flexible rotor analysis are compared to test data, with the correlation found to be good. Due to rapid convergence and multiple squeeze film capability, the procedure is particularly suited to large multishaft flexible rotor-bearing system analysis.

Design of a Squeeze-Film Damper for a Multi-Mass Flexible Rotor

1975 ◽  
Vol 97 (4) ◽  
pp. 1383-1389 ◽  
Author(s):  
Robert E. Cunningham ◽  
David P. Fleming ◽  
Edgar J. Gunter
Keyword(s):  
Computer Program ◽  
Critical Speed ◽  
Lubrication Theory ◽  
Squeeze Film ◽  
Flexible Rotor ◽  
Squeeze Film Damper ◽  
Flexible Support ◽  
Single Mass ◽  
Damper Design ◽  
Stiffness And Damping

A single mass flexible rotor analysis was used to optimize the stiffness and damping of a flexible support for a symmetric five-mass rotor. The flexible support attenuates the rotor motions and forces transmitted to the support bearings when the rotor operates through and above its first bending critical speed. An oil squeeze-film damper was designed based on short bearing lubrication theory. The damper design was verified by an unbalance response computer program. Rotor amplitudes were reduced by a factor of 16 and loads reduced by a factor of 36 compared with the same rotor on rigid bearing supports.

Updating Rotor-Bearing Finite Element Models

1997 ◽  
Author(s):  
Cristinel Mares ◽  
Cecilia Surace
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Parameters Estimation ◽  
Flexible Rotor ◽  
Estimation Errors ◽  
Rotor Bearing ◽  
Bearing Stiffness ◽  
Measured Frequency Response ◽  
Stiffness And Damping ◽  
The Finite Element Model

Abstract In this paper, the possibility of updating the finite element model of a rotor-bearing system by estimating the bearing stiffness and damping coefficients from a few measured Frequency Response Functions using a Genetic Algorithm is investigated. The issues of identifiability and parameters estimation errors, computational costs and algorithm tuning are addressed. A simulated example of a flexible rotor supported by orthotropic bearings is used for illustrating the method.

Squeeze Film Dampers: Amplitude Effects at Low Squeeze Numbers

1975 ◽  
Vol 97 (4) ◽  
pp. 1366-1370 ◽  
Author(s):  
Martin H. Sadd ◽  
A. Kent Stiffler
Keyword(s):  
Reynolds Equation ◽  
Dynamic Performance ◽  
Squeeze Film ◽  
Periodic Disturbance ◽  
Squeeze Film Dampers ◽  
Parallel Surfaces ◽  
Load Characteristics ◽  
Squeeze Number ◽  
Stiffness And Damping ◽  
Film Stiffness

Gaseous squeeze film dampers are analyzed to determine the effect of periodic disturbance amplitude on the dynamic performance. Both circular and rectangular parallel surfaces are investigated. A solution of the nonlinear Reynolds equation is obtained by expanding the pressure in powers of the squeeze number σ, retaining up to and including terms 0(σ2). The time dependent load characteristics are found. The effect of disturbance amplitude on the film stiffness and damping is given.

Theoretical and Experimental Studies on Squeeze Film Stabilizers for Flexible Rotor-Bearing Systems Using Newtonian and Viscoelastic Lubricants

1990 ◽  
Vol 112 (4) ◽  
pp. 473-482 ◽  
Author(s):  
B. Halder ◽  
A. Mukherjee ◽  
R. Karmakar
Keyword(s):  
High Speed ◽  
Experimental Studies ◽  
Squeeze Film ◽  
Experimental Investigations ◽  
Flexible Rotor ◽  
Stability Range ◽  
High Speeds ◽  
Flexible Rotors ◽  
Rotor Bearing

A combination of a squeeze film damper and a plane journal bearing is studied as a stabilizing scheme. The damper is made to play the role of a stabilizer to postpone the instability threshold speeds of flexible rotors. Both Newtonian and viscoelastic fluids are used in the rotor-bearing system. Dynamics of the system is theoretically analyzed using bond graphs. Analysis reveals that the use of a Newtonian fluid in the stabilizer largely improves the high speed stability range. However, viscoelastic stabilizing fluid has a detrimental effect on highly flexible rotors. Experimental investigations, conducted on a flexible rotor (natural frequency, 30 Hz), confirm the theoretical findings. In addition, experiments indicate that though the use of viscoelastic stabilizing fluids leads to instability in flexible rotors, the growth of large amplitude whirl is postponed to very high speeds.

Effect of Residual Shaft Bow on Unbalance Response and Balancing of a Single Mass Flexible Rotor—Part I: Unbalance Response

1976 ◽  
Vol 98 (2) ◽  
pp. 171-181 ◽  
Author(s):  
J. C. Nicholas ◽  
E. J. Gunter ◽  
P. E. Allaire
Keyword(s):  
Phase Angle ◽  
Response Speed ◽  
Rotor Speed ◽  
Flexible Rotor ◽  
Simple Method ◽  
Unbalance Response ◽  
Single Mass ◽  
Reverse Situation ◽  
Rigid Supports ◽  
Timing Mark

The effect of residual shaft bow on the unbalance response of a single mass rotor on rigid supports has been examined with a theoretical analysis. The analysis determined the amplitude, phase angle, and peak rotor response speed for various combinations of residual bow and unbalance. For most combinations the phase angle corresponding to the peak rotor response speed was significantly different from the 90 degrees observed in the conventional unbowed rotor. If the residual bow and unbalance were exactly out of phase, the rotor amplitude was zero for a rotor speed equal to the square root of the ratio of residual bow amplitude to unbalance eccentricity. The results of the study suggested a simple method for determining the relative amplitudes of residual bow and unbalance eccentricity based upon the motion of a timing mark on an oscilliscope screen. If the residual bow was less than the unbalance eccentricity, the timing mark moved first in the direction of rotor rotation as the speed is increased and then moved in the opposite direction at a speed less than the critical speed. In the reverse situation, the timing mark moved opposite to the direction of rotation as the speed is increased. At some speed above the critical, it reversed direction. Part II of this paper presents theoretical and experimental results for balancing of a single mass rotor with a residual bow.

Study of a Novel Squeeze Film Damper and Vibration Generator

1999 ◽  
Vol 122 (1) ◽  
pp. 211-218 ◽  
Author(s):  
C. V. Suciu ◽  
O. Bonneau ◽  
D. Brun-Picard ◽  
J. Fre^ne ◽  
M. D. Pascovici
Keyword(s):  
Reynolds Equation ◽  
Industrial Process ◽  
Vibration Damping ◽  
Squeeze Film ◽  
Squeeze Film Damper ◽  
Squeeze Film Effect ◽  
Stiffness And Damping ◽  
Film Stiffness ◽  
Wedge Effect ◽  
Theoretical Results

A novel squeeze film damper and vibration generator (SFD&VG) is proposed as an option in the vibration control field. The SFD&VG can be used as an active squeeze film damper (ASFD) or as a vibration generator (vibrator), for unidimensional vibration damping or generation. The SFD&VG concept is connected with current research to improve a common industrial process—drilling of deep holes. The SFD&VG is based on the variable area of the lubricant film, which allows the development of a variable force, and a change in fluid film stiffness and damping. The analysis is initiated for an elementary configuration of the SFD&VG—the infinite width Rayleigh step case—and then it is developed for an advanced elliptical SFD&VG. The Reynolds equation is solved for both pure squeeze film effect which provides vibration damping, and pure hydrodynamic wedge effect which provides vibration generation. The theoretical part is continued with the SFD&VG dynamic simulation. The SFD&VG experimental device and vibration measurements, performed for the two defined regimes, ASFD and vibration generator, are presented. Finally, the experimental and theoretical results are briefly compared. [S0742-4787(00)05201-2]

Gas Squeeze Film Stiffness and Damping Torques on a Circular Disk Oscillating About Its Diameter

1967 ◽  
Vol 89 (2) ◽  
pp. 219-221 ◽  
Author(s):  
J. S. Ausman
Keyword(s):  
Angular Velocity ◽  
Surface Area ◽  
Reynolds Equation ◽  
Circular Disk ◽  
Squeeze Film ◽  
Stiffness And Damping ◽  
Film Stiffness

A solution of Reynolds’ equation, linearized for small squeeze film motions, is presented which gives the pressure between two disks, one of which is oscillating about its diameter. Integration of the pressure over the surface area of the oscillating disk yields the squeeze film torque acting on it. The stiffness and damping components of this torque are those portions which oppose angular offset and angular velocity, respectively.

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