The Performance of a Sealed Squeeze-Film Bearing in a Flexible Support Structure

1985 ◽  
Vol 199 (1) ◽  
pp. 1-9 ◽  
Author(s):  
R Holmes ◽  
M Dogan
Keyword(s):  
Experimental Results ◽  
Squeeze Film ◽  
Support Structure ◽  
Outlet Pressure ◽  
Flexible Support ◽  
Leakage Factor ◽  
Aero Engine

In this paper attention is given to empirically modelling the hydrodynamics of a tightly sealed squeeze-film bearing in a flexible support structure simulating an aero-engine assembly, with a view to assessing its damping performance. It is found that predictable experimental results are obtained by employing an end-leakage factor which relates the outlet pressure around the bearing circumference to the corresponding ‘long-bearing’ pressure. The present work complements that covered in an earlier paper (1), which was concerned with the performance of an open-ended or weakly sealed squeeze-film bearing in a similar support structure.

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.

scholarly journals The Damping Capacity of a Sealed Squeeze Film Bearing

1985 ◽  
Vol 107 (3) ◽  
pp. 411-418 ◽  
Author(s):  
M. M. Dede ◽  
M. Dogan ◽  
R. Holmes
Keyword(s):  
Theoretical Model ◽  
Gas Turbine ◽  
Squeeze Film ◽  
Damping Capacity ◽  
Test Rig ◽  
Squeeze Film Damper ◽  
Aero Engine

The purpose of this paper is to establish a theoretical model to represent a sealed squeeze-film damper bearing and to assess it against results from a test rig, simulating the essential features of a medium-sized gas turbine aero engine.

Development of Compact Damper Bearing

2005 ◽  
Author(s):  
Hiroshi Kanki ◽  
Yosichika Sato ◽  
Takayuki Ueshima
Keyword(s):  
Rotating Machinery ◽  
Rolling Element Bearing ◽  
Squeeze Film ◽  
Test Results ◽  
Thin Ring ◽  
Compact Size ◽  
Standard Design ◽  
Rolling Element ◽  
Aero Engine ◽  
Element Bearing

The squeeze film damper bearings have been successfully applied for important rotating machinery such as aero engine, high pressure centrifugal compressors[1] and steam turbine[2]. This paper proposes the expansion of application of the damper bearing for small and medium sized rotating machinery. The new damper has a compact size that enable standard design combined with rolling element bearing. A new design of the damper is presented. The new design consists of thin ring and special patterned wire cut grooves. The design analysis and experimental study are presented. The dynamic tests were carried out for this model damper, one is no side seal and the other is with side seals in both ends. Test results showed the sufficient damping effect for actual applications.

Experimental Verification of Rarefied Gas Squeezed-Film Damping Models Used in MEMS

2006 ◽  
Author(s):  
Lukas Mol ◽  
Luis A. Rocha ◽  
Edmond Cretu ◽  
Reinoud F. Wolffenbuttel
Keyword(s):  
Experimental Verification ◽  
Parallel Plate ◽  
Rarefied Gas ◽  
Experimental Results ◽  
Squeeze Film ◽  
Border Effects ◽  
Knudsen Numbers ◽  
Electrostatic Mems ◽  
Simulation Errors

Existing compact parallel-plate squeeze-film models including rarefaction and border effects are verified using the experimental results of a new electrostatic MEMS actuation technique that enables full gap positioning. Measurements at high Knudsen numbers ranging from 0.03 to 0.18 are performed and results compared to the models. The simulation errors are confirmed to be lower than 20%. The experiments also indicate that both gas rarefaction and border effects have to be included in any model.

Flexible support structure design of lightweight thin reflector

2017 ◽  
Vol 38 (5) ◽  
pp. 618-622
Author(s):  
Yang Jianli ◽  
Qi Yuan ◽  
Yang Xiaoqiang ◽  
Zhu Lei ◽  
Teng Guoqi ◽  
...  
Keyword(s):  
Structure Design ◽  
Support Structure ◽  
Flexible Support

Eccentric Operation and Blade-Loss Simulation of a Rigid Rotor Supported by an Improved Squeeze Film Damper

1995 ◽  
Vol 117 (3) ◽  
pp. 490-497 ◽  
Author(s):  
J. Y. Zhao ◽  
E. J. Hahn
Keyword(s):  
Outer Ring ◽  
Squeeze Film ◽  
Rigid Rotor ◽  
Cavitation Model ◽  
Squeeze Film Damper ◽  
Constant Stiffness ◽  
Flexible Support ◽  
Squeeze Film Dampers ◽  
Stiffness And Damping ◽  
Blade Loss

This paper outlines an improved squeeze film damper which reduces significantly the dependence of the stiffness of conventional squeeze film dampers on the vibration amplitudes. This improved damper consists of a conventional squeeze film damper with a flexibility supported outer ring. This secondary flexible support is considered to be massless, and to have a constant stiffness and damping. Assuming the short bearing approximation and the ‘π’ film cavitation model, the performances of this damper in preventing bistable operation and sub-synchronous and nonsynchronous motions are theoretically demonstrated for a rigid rotor supported on a squeeze film damper. Blade-loss simulations are carried out numerically.

Design and analysis of micro stress flexible support structure of reflector in all day star tracker

2017 ◽  
Author(s):  
Yang Liu ◽  
Su Chen ◽  
Lingguang Wang ◽  
Bo Geng ◽  
Hu Wang ◽  
...  
Keyword(s):  
Star Tracker ◽  
Support Structure ◽  
Flexible Support

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.

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