Design Procedure for Evaluating Stability of Turbomachinery Supported on Squeeze Film Dampers

1995 ◽  
Vol 117 (4) ◽  
pp. 742-744 ◽  
Author(s):  
K. Ramesh ◽  
R. G. Kirk
Keyword(s):  
Design Procedure ◽  
Squeeze Film ◽  
Squeeze Film Dampers

Transformer Eddy Current Dampers for the Vibration Control

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Andrea Tonoli ◽  
Nicola Amati ◽  
Mario Silvagni
Keyword(s):  
Vibration Control ◽  
Eddy Current ◽  
Magnetic Circuit ◽  
Design Procedure ◽  
Squeeze Film ◽  
Lateral Vibration ◽  
Geometrical Characteristics ◽  
Squeeze Film Dampers ◽  
Lorentz Forces ◽  
Moving Conductor

Eddy current dampers are promising for the passive and semiactive vibration control of mechanical structures. Among them, the “motional” types are based on Lorentz forces between a moving conductor and a stationary magnetic field. On the contrary, “transformer” ones exploit electromagnetic forces varying the reluctance of the magnetic circuit due to the motion of a part of the damper. Considering the simplicity of the layout, transformer configurations seem to be very promising as alternative to traditional rubber or squeeze film dampers to control the lateral vibration of rotating machines. The aim of the present paper is to investigate the dynamic behavior of transformer eddy current dampers integrated in a mechanical structure. The electromechanical system is modeled using the Lagrange approach in terms of the magnetic flux linkages in the electromagnets. The mathematical models have been experimentally validated using two test benches with different layouts and geometrical characteristics of the magnetic circuit. The modeling approach allows to propose a design procedure of this type of damper.

The Optimal Design of Squeeze Film Dampers for Flexible Rotor Systems

1988 ◽  
Vol 110 (2) ◽  
pp. 166-174 ◽  
Author(s):  
W. J. Chen ◽  
M. Rajan ◽  
S. D. Rajan ◽  
H. D. Nelson
Keyword(s):  
Design Procedure ◽  
Optimization Techniques ◽  
Squeeze Film ◽  
Design Parameters ◽  
Element Formulation ◽  
Rotor Systems ◽  
Transmitted Force ◽  
Squeeze Film Dampers ◽  
Speed Range ◽  
Damper Design

Optimization techniques are employed to design squeeze film dampers for minimum transmitted load to the bearing and foundation in the operational speed range. The rotor systems are modeled by finite element formulation. The maximum transmitted load in the operational speed range is the objective function that is minimized using mathematical nonlinear programming (NLP) techniques. The damper design parameters are the radius, length, and radial clearance. Stability of the equilibrium solutions are investigated in the design procedure. Design derivatives have been determined in closed form expressions without resolution of the inherently nonlinear problem. A parametric study of the transmitted force is carried out to show the influence of damper parameters on the response and to demonstrate the merits of applying optimization techniques in damper design. Two numerical examples are presented that illustrate the effectiveness of optimizing squeeze film damper designs for reducing transmitted load.

Transformer Eddy Current Dampers for the Vibration Control of Rotating Machines

2006 ◽  
Author(s):  
Nicola Amati ◽  
Stefano Carabelli ◽  
Pietro Macchi ◽  
Mario Silvani ◽  
Andrea Tonoli
Keyword(s):  
Vibration Control ◽  
Eddy Current ◽  
Magnetic Circuit ◽  
Active Vibration Control ◽  
Design Procedure ◽  
Squeeze Film ◽  
Rotating Machines ◽  
Squeeze Film Dampers ◽  
Active Vibration ◽  
Moving Conductor

Eddy current dampers are promising devices for the passive and semi-active vibration control of mechanical structures. Among them “motional” eddy current dampers are based on the Lorentz forces between a moving conductor and a stationary magnetic field. “Transformer” eddy current dampers are based on the forces that develop in a voltage driven electromagnet when part of the magnetic circuit is movable. Considering the simplicity of the layout, transformer configurations seem to be very promising as alternative to traditional rubber or squeeze film dampers to control the lateral vibration of rotating machines. The aim of the present paper is to investigate the dynamic behavior of “transformer” eddy current dampers integrated in a mechanical structure. To this end the bond graph formalism is adopted with the aim of evidencing the causality effects between the mechanical and electromagnetic parts. The modeling approach allows to propose a design procedure of the damper. The mathematical models have been validated experimentally using two test benches with different layouts and geometrical characteristics of the magnetic circuit.

Nonlinear Analysis of Rotor-Bearing Systems Using Component Mode Synthesis

1983 ◽  
Vol 105 (3) ◽  
pp. 606-614 ◽  
Author(s):  
H. D. Nelson ◽  
W. L. Meacham ◽  
D. P. Fleming ◽  
A. F. Kascak
Keyword(s):  
Forced Response ◽  
Component Mode Synthesis ◽  
Squeeze Film ◽  
System Response ◽  
Reduced Order ◽  
Squeeze Film Dampers ◽  
Rotor Bearing ◽  
System Equations ◽  
Transient System ◽  
Blade Loss

The method of component mode synthesis is developed to determine the forced response of nonlinear, multishaft, rotor-bearing systems. The formulation allows for simulation of system response due to blade loss, distributed unbalance, base shock, maneuver loads, and specified fixed frame forces. The motion of each rotating component of the system is described by superposing constraint modes associated with boundary coordinates and constrained precessional modes associated with internal coordinates. The precessional modes are truncated for each component and the reduced component equations are assembled with the nonlinear supports and interconnections to form a set of nonlinear system equations of reduced order. These equations are then numerically integrated to obtain the system response. A computer program, which is presently restricted to single shaft systems has been written and results are presented for transient system response associated with blade loss dynamics, with squeeze film dampers, and with interference rubs.

Influence of different flow regimes on the performance characteristics of a four-pad hydrostatic squeeze film damper loaded between pads

2019 ◽  
Vol 71 (3) ◽  
pp. 440-446
Author(s):  
Amina Nemchi ◽  
Ahmed Bouzidane ◽  
Aboubakeur Benariba ◽  
Hicham Aboshighiba
Keyword(s):  
Turbulent Flow ◽  
Load Capacity ◽  
Flow Regimes ◽  
Performance Characteristics ◽  
Squeeze Film ◽  
Eccentricity Ratio ◽  
Flow Conditions ◽  
Content Type ◽  
Turbulent Flow Regime ◽  
Squeeze Film Dampers

Purpose The purpose of this paper is to study the influence of different flow regimes on the dynamic characteristics of four-pad hydrostatic squeeze film dampers (SFDs) loaded between pads. Design/methodology/approach A numerical model based on Constantinescu’s turbulent lubrication theory using the finite difference method has been developed and presented to study the effect of eccentricity ratio on the performance characteristics of four-pad hydrostatic SFDs under different flow regimes. Findings It was found that the influence of turbulent flow on the dimensionless damping of four-pad hydrostatic SFDs appears to be essentially controlled by the eccentricity ratio. It was also found that the laminar flow presents higher values of load capacity compared to bearings operating under turbulent flow conditions. Originality/value In fact, the results obtained show that the journal bearing performances are significantly influenced by the turbulent flow regime. The study is expected to be useful to bearing designers.

Experimental Evaluation of a Metal Mesh Bearing Damper

2000 ◽  
Vol 122 (2) ◽  
pp. 326-329 ◽  
Author(s):  
Mark Zarzour ◽  
John Vance
Keyword(s):  
Elevated Temperatures ◽  
Test Facility ◽  
Squeeze Film ◽  
Gas Generator ◽  
Metal Mesh ◽  
Previous Investigator ◽  
Spreadsheet Program ◽  
Squirrel Cage ◽  
Power Turbine ◽  
Squeeze Film Dampers

Metal mesh is a commercially available material used in many applications including seals, heat shields, filters, gaskets, aircraft engine mounts, and vibration absorbers. This material has been tested by the authors as a bearing damper in a rotordynamic test rig. The test facility was originally used to support the design of a turboprop engine, developing squirrel cages and squeeze film dampers for both the gas generator and power turbine rotors. To design the metal mesh damper, static stiffness and dynamic rap test measurements were first made on metal mesh samples in a specially designed nonrotating test fixture. These property tests were performed on samples of various densities and press fits. One sample was also tested in an Instron machine as an ancillary and redundant way to determine the stiffness. Using the stiffness test results and equations derived by a previous investigator, a spreadsheet program was written and used to size metal mesh donuts that have the radial stiffness value required to replace the squirrel cage in the power turbine. The squirrel cage and squeeze film bearing damper developed for the power turbine rotor was then replaced by a metal mesh donut sized by the computer code. Coast down tests were conducted through the first critical speed of the power turbine. The results of the metal mesh tests are compared with those obtained from previous testing with the squeeze film damper and show that the metal mesh damper has the same damping as the squeeze film at room temperature but does not lose its damping at elevated temperatures up to 103°C. Experiments were run under several different conditions, including balanced rotor, unbalanced rotor, heated metal mesh, and wet (with oil) metal mesh. The creep, or sag, of the metal mesh supporting the rotor weight was also measured over a period of several weeks and found to be very small. Based on these tests, metal mesh dampers appear to be a viable and attractive substitute for squeeze film dampers in gas turbine engines. The advantages shown by these tests include less variation of damping with temperature, ability to handle large rotor unbalance, and the ability (if required) to operate effectively in an oil free environment. Additional testing is required to determine the endurance properties, the effect of high impact or maneuver loads, and the ability to sustain blade loss loads (which squeeze films cannot handle). [S0742-4795(00)01002-4]

scholarly journals Dynamic Behavior of Geared Rotors

1997 ◽  
Author(s):  
T. N. Shiau ◽  
J. S. Rao ◽  
J. R. Chang ◽  
Siu-Tong Choi
Keyword(s):  
Dynamic Behavior ◽  
Chaotic Behavior ◽  
Squeeze Film ◽  
Rotor Systems ◽  
Lateral Vibrations ◽  
Squeeze Film Dampers ◽  
Torsional Excitation ◽  
Route To Chaos

This paper is concerned with the dynamic behavior of geared rotor systems supported by squeeze film dampers, wherein coupled bending torsion vibrations occur. Considering the imbalance forces and gravity, it is shown that geared rotors exhibit chaotic behavior due to non linearity of damper forces. The route to chaos in such systems is established. In geared rotor systems, it is shown that torsional excitation can induce lateral vibrations. It is shown that squeeze film dampers can suppress large amplitudes of whirl arising out of torsional excitation.

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