The Dynamic Characteristic Analysis of Elastic Ring Squeeze Film Damper by Fluid-Structure Interaction Approach

2017 ◽  
Author(s):  
ZhenLin Wang ◽  
Ning Xu ◽  
XiangYu Yu ◽  
ZhanSheng Liu ◽  
GuangHui Zhang
Keyword(s):  
Film Thickness ◽  
Volume Fraction ◽  
Squeeze Film ◽  
Elastic Ring ◽  
Characteristic Analysis ◽  
Oil Film ◽  
Squeeze Film Damper ◽  
Highly Nonlinear ◽  
Aero Engines ◽  
Interaction Approach

SFD (short for squeeze film damper) is a kind of passive vibration isolator widely used in rotor supporting structures of aero-engines for stabilization and vibration control. However, the conventional SFDs are highly nonlinear in terms of damping coefficient, which lead to complex response such as bitable state. In this paper, numerical simulations are carried out to investigate a new kind of SFD, elastic ring squeeze film damper (ERSFD). The elastic ring is modeled by FEM and the film is analyzed by CFD, the orifices on the ring is also included. An FSI approach is introduced to account for the influence of elastic ring’s deformation on oil film thickness. The Zwart-Gerber-Belamri model is included to account for air ingestion and cavitation in the damper land. The characteristics such as pressure distribution, oil film force and the deformation of the ring are obtained and compared with the results without FSI to reveal the self-adaptive mechanism of film thickness. The force coefficients for ERSFD are derived and gained by the FFT method. The dynamic coefficients for ERSFD versus whirl frequency are obtained and compared with corresponding air volume fraction.

scholarly journals Study on Vibration and Bifurcation of an Aeroengine Rotor System with Elastic Ring Squeeze Film Damper

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Guoying Pang ◽  
Shuqian Cao ◽  
Yushu Chen ◽  
Huizheng Chen
Keyword(s):  
Structural Parameters ◽  
Elastohydrodynamic Lubrication ◽  
Rolling Bearing ◽  
Rotor System ◽  
Squeeze Film ◽  
Force Model ◽  
Elastic Ring ◽  
Elastic Supports ◽  
Oil Film ◽  
Squeeze Film Damper

To analyze the problem of vibration and bifurcation in the rotor system of the aeroengine with the elastic ring squeeze film damper (ERSFD) and elastic supports, the theoretical equation of the dynamic rotor system is developed in this paper, based on the rotor system, elastic ring squeeze film damper (ERSFD), and three elastic supports. The estimated analytical solution of the oil film force is solved using the short bearing approximation theory and the semi-oil film inference theory in the suspension and the inner and outer boss contact. Considering the oil film stiffness and damping of rolling bearings, the rolling bearing force model is established based on the elastohydrodynamic lubrication (EHL) theory. By the average method, the vibration and bifurcation modes are obtained concerning the bearing coefficient and parameters. The range optimization of parameters can be appropriately improved to enhance the dynamic characteristics of the device given different parameters of the hole of oil seepage, the stiffness, the position of elastic supports, and other structural parameters.

scholarly journals Effectiveness Testing of an Inverse Method for Balancing Nonlinear Rotordynamic Systems

2018 ◽  
Author(s):  
Sergio G. Torres Cedillo ◽  
Philip Bonello ◽  
Ghaith Ghanim Al-Ghazal ◽  
Jacinto Cortés Pérez ◽  
Alberto Reyes Solis
Keyword(s):  
Inverse Problem ◽  
Inverse Method ◽  
Linear Connection ◽  
The Other ◽  
Squeeze Film ◽  
Squeeze Film Damper ◽  
Operational Conditions ◽  
Non Invasive ◽  
Highly Nonlinear ◽  
Aero Engine

Modern aero-engine structures typically have at least two nested rotors mounted within a flexible casing via squeeze-film damper (SFD) bearings. The inaccessibility of the HP rotor under operational conditions motivates the use of a non-invasive inverse problem procedure for identifying the unbalance. Such an inverse problem requires prior knowledge of the structure and measurements of the vibrations at the casing. Recent work by the authors reported a non-invasive inverse method for the balancing of rotordynamic systems with nonlinear squeeze-film damper (SFD) bearings, which overcomes several limitations of earlier works. However, it was not applied to a common practical configuration wherein the HP rotor is mounted on the casing via just one weak linear connection (retainer spring), with the other connections being highly nonlinear SFDs. The analysis of the present paper considers such a system. It explores the influence of the condition number and how it is affected as the number of sensors and/or measurement speeds is increased. The results show that increasing the number of measurement speeds has a far more significant impact on the conditioning of the problem than increasing the number of sensors. The balancing effectiveness is reasonably good under practical noise level conditions, but significantly lower than obtained for the previously considered simpler configurations.

Development of an Efficient Oil Film Damper for Improving the Control of Rotor Vibration

1991 ◽  
Vol 113 (4) ◽  
pp. 557-562 ◽  
Author(s):  
Shiping Zhang ◽  
Litang Yan
Keyword(s):  
High Speed ◽  
Porous Metal ◽  
Porous Matrix ◽  
Squeeze Film ◽  
Oil Film ◽  
Squeeze Film Damper ◽  
Outer Race ◽  
Typical Experiment ◽  
Stiffness And Damping ◽  
Film Stiffness

An efficient oil film damper known as a porous squeeze film damper (PSFD) was developed for more effective and reliable vibration control of high-speed rotors based on the conventional squeeze film damper (SFD). The outer race of the PSFD is made of permeable sintered porous metal materials. The permeability allows some of the oil to permeate into and seep out of the porous matrix, with remarkable improvement of the squeeze film damping properties. The characteristics of PSFD oil film stiffness and damping coefficients and permeability, and also, the steady-state unbalance response of a simple rigid rotor and flexible Jeffcott’s rotor supported on PSFD and SFD are investigated. A typical experiment is presented. Investigations show that the nonlinear vibration characteristics of the unpressurized SFD system such as bistable jump phenomena and “lockup” at rotor pin-pin critical speeds could be avoided and virtually disappear under much greater unbalance levels with properly designed PSFD system. PSFD has the potential advantage of operating effectively under relatively large unbalance conditions.

In Situ Estimation of the Dynamic Characteristics of an Uncavitated Squeeze-Film Damper

1988 ◽  
Vol 110 (1) ◽  
pp. 162-166
Author(s):  
C. R. Burrows ◽  
M. N. Sahinkaya ◽  
N. C. Kucuk ◽  
M. L. Tong
Keyword(s):  
Frequency Domain ◽  
Dynamic Characteristics ◽  
Estimation Algorithm ◽  
Squeeze Film ◽  
Oil Film ◽  
Squeeze Film Damper ◽  
Damping Coefficients ◽  
Theoretical Predictions

A modified form of the author’s frequency-domain estimation algorithm has been applied to estimate the inertia and damping coefficients of an uncavitated squeeze-film bearing. These estimates are obtained in situ from measurements on a specially designed rig. The experiments provided further evidence that oil-film inertia coefficients may be significant and showed that theoretical predictions are inadequate.

An Appraisal of a Proposed Active Squeeze Film Damper

1991 ◽  
Vol 113 (4) ◽  
pp. 750-754 ◽  
Author(s):  
C. Mu ◽  
J. Darling ◽  
C. R. Burrows
Keyword(s):  
Theoretical Model ◽  
Vibration Control ◽  
Numerical Experiments ◽  
Squeeze Film ◽  
Radial Clearance ◽  
Flexible Rotor ◽  
Oil Film ◽  
Squeeze Film Damper

A theoretical model for an active squeeze film damper (SFD) is introduced. The design makes it possible to change the radial clearance and land length of the SFD by adjusting the position of the damper ring. Expressions for the oil film forces are obtained. The vibration control of a flexible rotor is taken as an example of the application of the new design. The possibility of controlling rotor vibrations is demonstrated by means of numerical experiments.

The Effect of Journal Misalignment on the Oil-Film Forces Generated in a Squeeze Film Damper

1983 ◽  
Vol 105 (3) ◽  
pp. 560-564 ◽  
Author(s):  
R. A. Cookson ◽  
X. H. Feng ◽  
S. S. Kossa
Keyword(s):  
Computational Procedure ◽  
Squeeze Film ◽  
Radial Clearance ◽  
Oil Film ◽  
Squeeze Film Damper ◽  
Squeeze Film Dampers ◽  
Unbalance Force ◽  
Orbit Size ◽  
Journal Misalignment ◽  
Typical Calculation

Squeeze film damper performance is usually assessed on the assumption that the axis of the journal is parallel to that of the bearing housing. For many practical cases, for example that of the overhung fan shaft in an aero gas turbine, these two elements are unlikely to be parallel, even when self-aligning bearings are used. In this theoretical study an attempt has been made to evaluate the effect of misalignment on the magnitude of the oil-film forces produced in a squeeze film damper bearing, and to this end a computational procedure has been established. From the results reported in this paper, it has been clearly shown that the effect of misalignment in a two-land, squeeze film damper can lead to a significant increase in the transmission of unbalance force through the oil film, As an example, data from a previously reported investigation into the performance of a simple two-bearing model with a single centrally supported disk have been used in a typical calculation. The results from this computation indicated that the oil-film forces generated, could have been several times greater than those calculated on the assumption that the journal and bearing housing were parallel. Unfortunately, there do not appear to be any clear guidelines to lay down to the designers of squeeze film dampers at this moment, in relation to journal misalignment. In general, the effect of misalignment is strongest when the ratio of land-length to radial clearance is greatest, when large unbalance is being accommodated, and when the orbit size is large. In our own analytical studies, the effect of misalignment is allowed for whenever the angle of misalignment is greater than 0.0005 radians.

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