Effect of Fluid Inertia on Squeeze-Film Damper Forces for Small-Amplitude Circular-Centered Motions

1987 ◽  
Vol 30 (1) ◽  
pp. 63-68 ◽  
Author(s):  
Luis A. San Andres ◽  
John M. Vance
Keyword(s):  
Small Amplitude ◽  
Squeeze Film ◽  
Fluid Inertia ◽  
Squeeze Film Damper

Squeeze Film Damper Suppression of Thermal Bow: Morton Effect Instability

2020 ◽  
Author(s):  
Dongil Shin ◽  
Alan B. Palazzolo ◽  
Xiaomeng Tong
Keyword(s):  
Squeeze Film ◽  
Viscous Heating ◽  
Fluid Inertia ◽  
Euler Beam ◽  
Nonlinear Simulation ◽  
Squeeze Film Damper ◽  
Morton Effect ◽  
Tilting Pad ◽  
Tilting Pad Journal Bearing ◽  
Rotor Model

Abstract The Morton Effect (ME) is a synchronous vibration problem in turbomachinery caused by the non-uniform viscous heating around the journal circumference, and its resultant thermal bow and ensuing synchronous vibration. This paper treats the unconventional application of the SFD for the mitigation of ME-induced vibration. Installing a properly designed squeeze film damper (SFD) may change the rotor’s critical speed location, damping and deflection shape, and thereby suppress the vibration caused by the ME. The effectiveness of the SFD on suppressing the ME is tested via linear and nonlinear simulation studies employing a 3D thermo-hydrodynamic (THD) tilting pad journal bearing, and a flexible, Euler beam rotor model. The example rotor model is for a compressor that experimentally exhibited an unacceptable vibration level along with significant journal differential heating near 8,000 rpm. The SFD model includes fluid inertia and is installed on the non-drive end bearing location where the asymmetric viscous heating of the journal is highest. The influence of SFD cage stiffness is evaluated.

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.

Study of Static Fluid Forces in a Squeeze Film Damper with a Circumferential Groove

1995 ◽  
Vol 209 (4) ◽  
pp. 263-274
Author(s):  
J X Zhang
Keyword(s):  
Fluid Pressure ◽  
Squeeze Film ◽  
Fluid Inertia ◽  
Traditional Use ◽  
Fluid Force ◽  
Squeeze Film Damper ◽  
Fluid Forces ◽  
Supply Pressure ◽  
Static Fluid ◽  
Approximate Expressions

Approximate expressions are obtained for static fluid pressure and force for a centrally grooved squeeze film damper (SFD) resting at an equilibrium position without vibration. The analysis shows that, to some extent, grooved SFDs may share some characteristics with hydrostatic bearings, due to the existence of the lubricant supply pressure. Thus static fluid force and hence oil stiffness may exist in SFDs, in addition to the conventional inertial and damping coefficients for SFDs. This paper is solely focused on the static fluid forces and oil stiffness generated in an SFD with a finite length groove. Flow continuity is used at the centre of the groove, which takes into account the effects of the inlet oil flowrate and oil supply pressure. This use of flow continuity differs substantially from the traditional use of constant pressure in the central groove, and it provides better results. At the interface between the groove and the thin film land, a step bearing model with ignored fluid inertia is employed. It is verified by both the theory and previous experiments that the static fluid force and stiffness are linearly proportional to both the lubricant supply pressure and the eccentricity ratio of the SFD journal.

Squeeze Film Damper Suppression of Thermal Bow-Morton Effect Instability

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Dongil Shin ◽  
Alan B. Palazzolo ◽  
Xiaomeng Tong
Keyword(s):  
Three Dimensional ◽  
Squeeze Film ◽  
Viscous Heating ◽  
Fluid Inertia ◽  
Euler Beam ◽  
Nonlinear Simulation ◽  
Squeeze Film Damper ◽  
Morton Effect ◽  
Tilting Pad Journal Bearing ◽  
Rotor Model

Abstract The Morton effect (ME) is a synchronous vibration problem in turbomachinery caused by the nonuniform viscous heating around the journal circumference, and its resultant thermal bow (TB) and ensuing synchronous vibration. This paper treats the unconventional application of the SFD for the mitigation of ME-induced vibration. Installing a properly designed squeeze film damper (SFD) may change the rotor's critical speed location, damping, and deflection shape, and thereby suppress the vibration caused by the ME. The effectiveness of the SFD on suppressing the ME is tested via linear and nonlinear simulation studies employing a three-dimensional (3D) thermohydrodynamic (THD) tilting pad journal bearing (TJPB), and a flexible, Euler beam rotor model. The example rotor model is for a compressor that experimentally exhibited an unacceptable vibration level along with significant journal differential heating near 8000 rpm. The SFD model includes fluid inertia and is installed on the nondrive end bearing location where the asymmetric viscous heating of the journal is highest. The influence of SFD cage stiffness is evaluated.

scholarly journals Squeeze Film Dampers Executing Small Amplitude Circular-Centered Orbits in High-Speed Turbomachinery

2016 ◽  
Vol 2016 ◽  
pp. 1-16 ◽  
Author(s):  
Sina Hamzehlouia ◽  
Kamran Behdinan
Keyword(s):  
Pressure Distribution ◽  
Small Amplitude ◽  
High Speed ◽  
Fluid Film ◽  
Distribution Model ◽  
Squeeze Film ◽  
Fluid Inertia ◽  
Inertia Effects ◽  
Squeeze Film Dampers ◽  
Reaction Forces

This work represents a pressure distribution model for finite length squeeze film dampers (SFDs) executing small amplitude circular-centered orbits (CCOs) with application in high-speed turbomachinery design. The proposed pressure distribution model only accounts for unsteady (temporal) inertia terms, since based on order of magnitude analysis, for small amplitude motions of the journal center, the effect of convective inertia is negligible relative to unsteady (temporal) inertia. In this work, the continuity equation and the momentum transport equations for incompressible lubricants are reduced by assuming that the shapes of the fluid velocity profiles are not strongly influenced by the inertia forces, obtaining an extended form of Reynolds equation for the hydrodynamic pressure distribution that accounts for fluid inertia effects. Furthermore, a numerical procedure is represented to discretize the model equations by applying finite difference approximation (FDA) and to numerically determine the pressure distribution and fluid film reaction forces in SFDs with significant accuracy. Finally, the proposed model is incorporated into a simulation model and the results are compared against existing SFD models. Based on the simulation results, the pressure distribution and fluid film reaction forces are significantly influenced by fluid inertia effects even at small and moderate Reynolds numbers.

Effect of Fluid Inertia on the Performance of Squeeze Film Damper Supported Rotors

1988 ◽  
Vol 110 (1) ◽  
pp. 51-57 ◽  
Author(s):  
L. A. San Andres ◽  
J. M. Vance
Keyword(s):  
Aircraft Engine ◽  
Reynolds Numbers ◽  
Squeeze Film ◽  
Fluid Inertia ◽  
Response Curves ◽  
Squeeze Film Damper ◽  
Steady State Operation ◽  
Transmitted Force ◽  
Jump Phenomena ◽  
Single Mass

The effect of fluid inertia on the synchronous steady-state operation of a centrally preloaded single mass flexible rotor supported in squeeze film bearing dampers is examined theoretically. For a model representative of some aircraft engine applications, frequency response curves are presented exhibiting the effect of fluid inertia on rotor excursion amplitudes and imbalance transmissibilities for both pressurized and unpressurized short open-ended squeeze film damper supports. It is shown that a significant reduction in amplitude response and transmitted force is possible for dampers operating at moderately large squeeze film Reynolds numbers. Furthermore, for unpressurized dampers the possibilities of bistable operation and jump phenomena are shown to be reduced and virtually disappear at sufficiently large operating Reynolds numbers.

Application of the k-ε Turbulence Model to the Squeeze Film Damper

1987 ◽  
Vol 109 (1) ◽  
pp. 164-168 ◽  
Author(s):  
Chiao-Ping Ku ◽  
John A. Tichy
Keyword(s):  
High Speed ◽  
Transport Model ◽  
Tangential Force ◽  
Fluid Pressure ◽  
Radial Force ◽  
Squeeze Film ◽  
Fluid Inertia ◽  
Damping Force ◽  
Mean Velocity ◽  
Squeeze Film Damper

The one-dimensional squeeze film damper is modeled for high speed flow by using the two-equation (k-ε) turbulent transport model. The assumption is made that the fluid flow at each local region of the squeeze film damper has similar behavior to inertialess flow in a channel at comparable Reynolds number. Using the k-ε model, the inertialess channel flow case is solved. Based on this result, correlations are obtained for the mean velocity, inertia and viscous terms of the integrated momentum equation for the squeeze film damper. It is found that turbulence increases the magnitude of the fluid pressure and the tangential force, while fluid inertia causes a shift on the pressure creating a significant radial force. In applications, turbulence may be a beneficial effect, increasing the principal damping force; while inertia may be detrimental increasing the cross-coupling forces.

Bifurcation analysis of rotor–squeeze film damper system with fluid inertia

2014 ◽  
Vol 81 ◽  
pp. 129-139 ◽  
Author(s):  
Huizheng Chen ◽  
Yushu Chen ◽  
Lei Hou ◽  
Zhonggang Li
Keyword(s):  
Bifurcation Analysis ◽  
Squeeze Film ◽  
Fluid Inertia ◽  
Squeeze Film Damper

Analysis of Short Squeeze Film Dampers With a Central Groove

1992 ◽  
Vol 114 (4) ◽  
pp. 659-664 ◽  
Author(s):  
Luis A. San Andres
Keyword(s):  
Squeeze Film ◽  
Inertia Force ◽  
Dynamic Force ◽  
Fluid Inertia ◽  
Dynamic Flow ◽  
Low Frequencies ◽  
Squeeze Film Damper ◽  
Force Coefficients ◽  
Squeeze Film Dampers ◽  
Combined Action

A novel analysis for the dynamic force response of a squeeze film damper with a central feeding groove considers the dynamic flow interaction between the squeeze film lands and the feeding groove. For small amplitude centered motions and based on the short bearing model, corrected values for the damping and inertia force coefficients are determined. Correlations with existing experimental evidence is excellent. Analytical results show that the grooved-damper behaves at low frequencies as a single land damper. Dynamic force coefficients are determined to be frequency dependent. Analytical predictions show that the combined action of fluid inertia and groove volume—liquid compressibility affects the force coefficients for dynamic excitation at large frequencies.

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