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.

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.

scholarly journals An Investigation Into the Effect of Side-Plate Clearance in an Uncentralized Squeeze-Film Damper

1983 ◽  
Author(s):  
R. A. Cookson ◽  
L. J. Dainton
Keyword(s):  
Experimental Investigation ◽  
Rolling Contact ◽  
Squeeze Film ◽  
Radial Clearance ◽  
Flexible Rotor ◽  
Jump Phenomenon ◽  
Side Plate ◽  
Squeeze Film Damper ◽  
Squeeze Film Dampers ◽  
Experimental Rig

An experimental investigation has been carried out into the influence of side-plate flow restrictors on the performance of a squeeze-film damper bearing. The experimental rig used was a flexible rotor with a disc positioned mid-way between two squeeze-film damper bearings. One of the squeeze-film dampers was fitted with side-plates which could be adjusted and accurately located with respect to the squeeze-film damper journal. It has been found that the influence of the side-plate clearance on the ability of the squeeze-film damper to reduce the amplitude of the central disc can be considerable if the side-plate clearance is less than the radial clearance. As the side-plate clearance reduces towards zero, the effectiveness of the squeeze-film damper diminishes until the amplitudes obtained are the same as those measured when the rolling-contact bearing is rigidly supported. An interesting type of precessing elliptical orbit was discovered for conditions where the ‘jump’ phenomenon was operating.

An Investigation Into the Effect of Side-Plate Clearance in an Uncentralized Squeeze Film Damper

1983 ◽  
Vol 105 (4) ◽  
pp. 935-940
Author(s):  
R. A. Cookson ◽  
L. J. Dainton
Keyword(s):  
Rolling Contact ◽  
Squeeze Film ◽  
Radial Clearance ◽  
Flexible Rotor ◽  
Jump Phenomenon ◽  
Side Plate ◽  
Squeeze Film Damper ◽  
Central Disk ◽  
Squeeze Film Dampers ◽  
Experimental Rig

An experimental investigation has been carried out into the influence of side-plate flow restrictors on the performance of a squeeze film damper bearing. The experimental rig used was a flexible rotor with a disk positioned midway between two squeeze film damper bearings. One of the squeeze film dampers was fitted with side plates that could be adjusted and accurately located with respect to the squeeze film damper journal. It has been found that the influence of the side-plate clearance on the ability of the squeeze film damper to reduce the amplitude of the central disk can be considerable if the side-plate clearance is less than the radial clearance. As the side-plate clearance reduces towards zero, the effectiveness of the squeeze film damper diminishes until the amplitudes obtained are the same as those measured when the rolling-contact bearing is rigidly supported. An interesting type of precessing elliptical orbit was discovered for conditions where the “jump” phenomenon was operating.

scholarly journals A computational fluid dynamics investigation of the segmented integral squeeze film damper

2019 ◽  
Vol 254 ◽  
pp. 08005 ◽  
Author(s):  
Petr Ferfecki ◽  
Jaroslav Zapoměl ◽  
Marek Gebauer ◽  
Václav Polreich ◽  
Jiří Křenek
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Squeeze Film ◽  
Squeeze Film Damper ◽  
Ansys Cfx ◽  
Squeeze Film Dampers ◽  
Tilting Pad ◽  
Vibration Attenuation ◽  
Tilting Pad Journal Bearing

Rotor vibration attenuation is achieved with damping devices which work on different, often mutually coupled, physical principles. Squeeze film dampers are damping devices that have been widely used in rotordynamic applications. A new concept of a 5-segmented integral squeeze film damper, in which a flexure pivot tilting pad journal bearing is integrated, was investigated. The damper is studied for the eccentric position between the outer and inner ring of the squeeze film land. The ANSYS CFX software was used for solving the pressure and velocity distribution. The development of the complex three-dimensional computational fluid dynamics model of the squeeze film damper, learning more about the effect of the forces in the damper, and the knowledge about the behaviour of the flow are the principal contributions of this article.

Dynamic Analysis of a Coupled Dual-Rotor With Squeeze Film Damper Considering Sudden Unbalance

2021 ◽  
Author(s):  
Ying Cui ◽  
Yuxi Huang ◽  
Guogang Yang ◽  
Yongliang Wang ◽  
Han Zhang
Keyword(s):  
Steady State ◽  
Transient Response ◽  
Rotor System ◽  
Lubricating Oil ◽  
Squeeze Film ◽  
Radial Clearance ◽  
Oil Viscosity ◽  
Squeeze Film Damper ◽  
Damping Effect ◽  
Bistable State

Abstract A nonlinear multi-degree-of-freedom dynamic model of a coupled dual-rotor system with an intershaft bearing and uncentralized squeeze film damper is established by using finite element method. Based on the model, the critical speed characteristic diagram and vibration modes of the system were calculated. The steady-state unbalance response is obtained by using Newmark-β algorithm. The numerical results show the effect of SFD position in the dual-rotor system on response amplitude. It is found that with the decrease of radial clearance and the increase of length-diameter ratio and lubricating oil viscosity, the damping effect of SFD is enhanced and the bistable state phenomenon can be suppressed. The transient response of the system in case of sudden unbalance occurring at the fan was simulated by applying a step function. It is demonstrated that the SFD can effectively reduce the duration and maximum amplitude of the transient process, but at certain speeds, the SFD will increase the amplitude after the system returns to steady state, the damping effect on the transient response is also enhanced with the increase of length-diameter and the decrease of radial clearance, and with the increase of the sudden unbalance value, the response is more likely to stabilized at the high amplitude state of the bistable state.

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.

Dynamic Response of Squeeze Film Dampers Operating With Bubbly Mixtures

2002 ◽  
Author(s):  
Luis San Andre´s ◽  
Oscar C. De Santiago
Keyword(s):  
Load Transfer ◽  
Transfer Functions ◽  
Dynamic Performance ◽  
Air Entrainment ◽  
Squeeze Film ◽  
Radial Clearance ◽  
Performance Impact ◽  
Air Content ◽  
Squeeze Film Dampers ◽  
Oil Mixtures

Squeeze film dampers (SFDs) aid to attenuate vibrations in compressors and turbines while traversing critical speeds. In actual applications, gas ingestion from the environment may lead to the formation of a foamy lubricant that degrades the rotor/bearing system dynamic performance. Impact and imbalance response tests conducted on a rigid rotor supported on SFDs, and aimed to emulate the pervasive effect of air ingestion into the damper film lands, are reported. Two types of squeeze film damper support the test rotor, one is a conventional cylindrical design with a squirrel cage type elastic support, and the other is a compact four-pad damper with integral wire EDM elastic supports. Both dampers have identical diameter and radial clearance. Controlled (air in oil) mixtures ranging from pure oil to all air conditions are supplied to the SFDs, and measurements of the transient rotor response to calibrated impact loads are conducted. System damping coefficients, identified from acceleration/load transfer functions, decrease steadily as the air content in the mixture increases. However, measurements of the rotor synchronous imbalance response conducted with a lubricant bubbly mixture (50% air volume) show little difference with test results obtained with pure lubricant supplied to the dampers. The experimental results show that air entrainment is process and device dependent, and that small amounts of lubricant enable the effective action of SFDs when the rotor traverses a critical speed.

Application of computational fluid dynamics for thermohydrodynamic analysis of high-speed squeeze-film dampers

2019 ◽  
Vol 43 (3) ◽  
pp. 306-321 ◽  
Author(s):  
Maxime Perreault ◽  
Sina Hamzehlouia ◽  
Kamran Behdinan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Speed ◽  
Operating Conditions ◽  
Squeeze Film ◽  
Radial Clearance ◽  
Base Line ◽  
Squeeze Film Dampers ◽  
Shaft Deflection ◽  
Whirl Speed

In high-speed turbomachinery, the presence of rotor vibrations, which produce undesirable noise or shaft deflection and losses in performance, has brought up the need for the application of a proper mechanism to attenuate the vibration amplitudes. Squeeze-film dampers (SFDs) are a widely employed solution to the steady-state vibrations in high-speed turbomachinery. SFDs contain a thin film of lubricant that is susceptible to changes in temperature. For this reason, the analysis of thermohydrodynamic (THD) effects on the SFD damping properties is essential. This paper develops a computational fluid dynamics (CFD) model to analyze the THD effects in SFDs, and enabling the application of CFD analysis to be a base-line for validating the accuracy of analytical THD SFD models. Specifically, the CFD results are compared against numerical simulations at different operating conditions, including eccentricity ratios and journal whirl speeds. The comparisons demonstrate the effective application of CFD for THD analysis of SFDs. Additionally, the effect of the lubricant THDs on the viscosity, maximum and mass-averaged temperature, as well as heat generation rates inside the SFD lubricant are analyzed. The temperature of the lubricant is seen to rise with increasing whirl speed, eccentricity ratios, damper radial clearance, and shaft radii.

Application of CFD Analysis for Rotating Machinery: Part 1 — Hydrodynamic, Hydrostatic Bearings and Squeeze Film Damper

2003 ◽  
Author(s):  
Zenglin Guo ◽  
Toshio Hirano ◽  
R. Gordon Kirk
Keyword(s):  
Traditional Method ◽  
Reasonable Agreement ◽  
Pressure Field ◽  
Squeeze Film ◽  
Cfd Analysis ◽  
Complex Flow ◽  
Static And Dynamic Characteristics ◽  
Squeeze Film Damper ◽  
Squeeze Film Dampers ◽  
Machinery Part

The traditional method for bearing and damper analysis usually involves a development of rather complicated numerical calculation programs that may just focus on a simplified and specific physical model. The application of the general CFD codes may make this analysis available and effective where complex flow geometries are involved or when more detailed solutions are needed. In this study, CFX-TASCflow is employed to simulate various fixed geometry fluid-film bearing and damper designs. Some of the capabilities in CFX-TASCflow are applied to simulate the pressure field and calculate the static and dynamic characteristics of hydrodynamic, hydrostatic and hybrid bearings as well as squeeze film dampers. The comparison between the CFD analysis and current computer programs used in industry has been made. The results show reasonable agreement in general. Some of possible reasons for the differences are discussed. It leaves room for further investigation and improvement on the methods of computation.

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