Dynamic analysis of a bevel gear system equipped with finite length squeeze film dampers for passive vibration control

2020 ◽  
Vol 147 ◽  
pp. 103779 ◽  
Author(s):  
Weitao Chen ◽  
Siyu Chen ◽  
Zehua Hu ◽  
Jinyuan Tang ◽  
Haonan Li
Keyword(s):  
Dynamic Analysis ◽  
Vibration Control ◽  
Finite Length ◽  
Bevel Gear ◽  
Gear System ◽  
Squeeze Film ◽  
Passive Vibration Control ◽  
Squeeze Film Dampers

scholarly journals Squeeze-Film Damper Technology: Part 1 — Prediction of Finite Length Damper Performance

1983 ◽  
Author(s):  
J. W. Lund ◽  
A. J. Smalley ◽  
J. A. Tecza ◽  
J. F. Walton
Keyword(s):  
Finite Length ◽  
Gas Turbines ◽  
Squeeze Film ◽  
Fluid Inertia ◽  
Inertia Effects ◽  
Strongly Coupled ◽  
Squeeze Film Damper ◽  
Rotor Systems ◽  
Squeeze Film Dampers ◽  
Calculation Results

Squeeze-film dampers are commonly used in gas turbine engines and have been applied successfully in a great many new designs, and also as retrofits to older engines. Of the mechanical components in gas turbines, squeeze-film dampers are the least understood. Their behavior is nonlinear and strongly coupled to the dynamics of the rotor systems on which they are installed. The design of these dampers is still largely empirical, although they have been the subject of a large number of past investigations. To describe recent analytical and experimental work in squeeze-film damper technology, two papers are planned. This abstract outlines the first paper, Part 1, which concerns itself with squeeze-film damper analysis. This paper will describe an analysis method and boundary conditions which have been developed recently for modelling dampers, and in particular, will cover the treatment of finite length, feed and drain holes and fluid inertia effects, the latter having been shown recently to be of great importance in predicting rotor system behavior. A computer program that solves the Reynolds equation for the above conditions will be described and sample calculation results presented.

A Theoretical Series Solution for the Dynamics of Finite-Length Bearings and Squeeze-Film Dampers

2003 ◽  
Author(s):  
Jose´ Antunes ◽  
Miguel Moreira ◽  
Philippe Piteau
Keyword(s):  
Fourier Series ◽  
Galerkin Method ◽  
Finite Length ◽  
Reynolds Equation ◽  
Double Fourier Series ◽  
Squeeze Film ◽  
Algebraic Equations ◽  
Squeeze Film Dampers ◽  
Galerkin Solution ◽  
The Galerkin Method

In this paper we develop a non-linear dynamical solution for finite length bearings and squeeze-film dampers based on a Spectral-Galerkin method. In this approach the gap-averaged pressure is approximated, in the lubrication Reynolds equation, by a truncated double Fourier series. The Galerkin method, applied over the residuals so obtained, generate a set of simultaneous algebraic equations for the time-dependent coefficients of the double Fourier series for the pressure. In order to assert the validity of our 2D–Spectral-Galerkin solution we present some preliminary comparative numerical simulations, which display satisfactory results up to eccentricities of about 0.9 of the reduced fluid gap H/R. The so-called long and short-bearing dynamical solutions of the Reynolds equation, reformulated in Cartesian coordinates, are also presented and compared with the corresponding classic solutions found on literature.

Vibration Control of a Rotor System Utilizing a Bearing Housing With Controllable Spring Nonlinearity

1994 ◽  
Author(s):  
Baojiang Liu ◽  
Litang Yan ◽  
Qihan Li ◽  
Zigen Zhu
Keyword(s):  
Vibration Control ◽  
Nonlinear Vibration ◽  
Dynamic Behaviour ◽  
Rotor System ◽  
Experimental Results ◽  
Squeeze Film ◽  
Solution Curve ◽  
Operating Process ◽  
Squeeze Film Dampers ◽  
Vibration Performance

On the basis of characteristics of vibration in the rotor system with spring nonlinearity, a new method for vibration control has been developed. In the method, the spring characteristics of a bearing housing are controlled to be of softening nonlinearity when the rotor supported on it is accelerated and to be of hardening one when it is decelerated. So vibratory amplitudes of the rotor system always vary along the smallest solution curve in the whole operating process. A model of vibration of the rotor system supported on the controllable hearing housing is derived. Its dynamic behaviour is predicted and verified by experiments. Both theoretical and experimental results show that not only vibratory amplitudes and transmitted forces are suppressed significantly but also nonlinear vibration performance of the rotor supported on squeeze film dampers, such as “lock up” at rotor pin-pin critical speeds and asynchronous vibration, can be avoided.

Effects of Fluid Inertia on Finite-Length Squeeze-Film Dampers

1987 ◽  
Vol 30 (3) ◽  
pp. 384-393 ◽  
Author(s):  
L. A. San Andres ◽  
J. M. Vance
Keyword(s):  
Finite Length ◽  
Squeeze Film ◽  
Fluid Inertia ◽  
Squeeze Film Dampers

On the Numerical Prediction of Finite Length Squeeze Film Dampers Performance With Free Air Entrainment

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Tilmer H. Méndez ◽  
Jorge E. Torres ◽  
Marco A. Ciaccia ◽  
Sergio E. Díaz
Keyword(s):  
Finite Length ◽  
Air Entrainment ◽  
Squeeze Flow ◽  
Squeeze Film ◽  
Air Entrapment ◽  
Film Rupture ◽  
Subsequent Formation ◽  
Squeeze Film Dampers ◽  
Entrained Air ◽  
San Andres

Squeeze film dampers (SFDs) are commonly used in turbomachinery to dampen shaft vibrations in rotor-bearing systems. The main factor deterring the success of analytical models for the prediction of SFD’s performance lies on the modeling of dynamic film rupture. Usually, the cavitation models developed for journal bearings are applied to SFDs. Yet, the characteristic motion of the SFD results in the entrapment of air into the oil film, producing a bubbly mixture that cannot be represented by these models. There is a need to identify and understand the parameters that affect air entrainment and subsequent formation of a bubbly air-oil mixture within the lubricant film. A previous model by and Diazand San Andrés (2001, “A Model for Squeeze Film Dampers Operating With Air Entrapment and Validation With Experiments,” ASME J. Tribol., 123, pp. 125–133) advanced estimation of the amount of film-entrapped air based on a nondimensional number that related both geometrical and operating parameters but limited to the short bearing approximation (i.e., neglecting circumferential flow). The present study extends their work to consider the effects of finite length-to-diameter ratios. This is achieved by means of a finite volume integration of the two-dimensional, Newtonian, compressible Reynolds equation combined with the effective mixture density and viscosity defined in the work of Diaz and San Andrés. A flow balance at the open end of the film is devised to estimate the amount of air entrapped within the film. The results show, in dimensionless plots, a map of the amount of entrained air as a function of the feed-squeeze flow number, defined by Diaz and San Andrés, and the length-to-diameter ratio of the damper. Entrained air is shown to decrease as the L/D ratio increases, going from the approximate solution of Diaz and San Andrés for infinitely short SFDs down to no air entrainment for an infinite length SFD. The results of this research are of immediate engineering applicability. Furthermore, they represent a firm step to advance the understanding of the effects of air entrapment on the performance of SFDs.

Chebyshev Polynomials Fits for Efficient Analysis of Finite Length Squeeze Film Damped Rotors

2002 ◽  
Vol 125 (1) ◽  
pp. 175-183 ◽  
Author(s):  
F. A. Rodrigues ◽  
F. Thouverez ◽  
C. Gibert ◽  
L. Jezequel
Keyword(s):  
Steady State ◽  
Finite Length ◽  
Pressure Field ◽  
Fluid Pressure ◽  
Harmonic Balance Method ◽  
Nonlinear Behavior ◽  
Squeeze Film ◽  
Approximate Methods ◽  
Squeeze Film Dampers ◽  
The Time Domain

The nonlinear behavior of the hydrodynamic forces generated by squeeze film dampers makes dynamical analyses of rotor-bearing systems incorporating such devices a complex and often long task. When steady-state orbits are to be sought, approximate methods (e.g., harmonic balance method, trigonometric collocation method) can be used in order to save computation cost. However, numerical integration in the time domain cannot be avoided if one wishes to calculate transient responses, or to carry out more meticulous analyses concerning the effects of the damper nonlinear nature on the motion of the system. For finite length squeeze film dampers, neither the short nor the long bearing approximations can be suitably applied, and the fluid pressure field has to be estimated numerically, thus rendering rotordynamics predictions even longer and, for engineering purposes computationally prohibitive. To surmount this problem, the present paper proposes a straightforward procedure to derive polynomial expressions for the squeeze film damper (SFD) forces, for given damper geometry and boundary conditions. This is achieved by applying Chebyshev orthogonal polynomial fits over force data generated by numerically solving the two-dimensional pressure field governing equation. For both transient and steady-state calculations, the use of the SFD forces polynomial expressions is seen to be very efficient and precise.

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.

Rotordynamic Performance of Finite Length Squeeze Film Dampers

2003 ◽  
Author(s):  
A. El-Shafei ◽  
A. S. El-Kabbany
Keyword(s):  
Finite Length ◽  
Reynolds Equation ◽  
Squeeze Film ◽  
Rigid Rotor ◽  
Damping Coefficients ◽  
At Resonance ◽  
R Ratio ◽  
Squeeze Film Dampers ◽  
Current Design ◽  
Analytical Formulae

A recently developed finite length model of squeeze film dampers is extended and used in predicting the behavior of a rigid rotor supported by squeeze film dampers (SFDs). The model is based on a perturbation solution of Reynolds’ equation. The finite length SFD damping coefficients are presented for various L/R ratios. The effect of damper finite length is studied. Simulations of the behavior of a rigid rotor with the finite length SFDs illustrate the response of the roto-rbearing system. The accuracy of the finite damper model is shown for cases comparable to short and long dampers models. The short damper and long damper models are generally accepted to be valid for L/D < 1/4, and for L/D > 4, respectively. The capability of the finite length damper model to capture the main essence of the L/R ratio on the rotor response at resonance is illustrated. Analytical formulae for damping estimates are provided for finite length dampers. It is shown that the finite length damper actually provides less damping than either the short or the long damper models, which means that current design practices actually overestimate the SFD damping capabilities.

Sign in / Sign up

Export Citation Format

Share Document