An analytical model for open-ended squeeze film damper with a circumferential central groove

2021 ◽  
pp. 135065012098765
Author(s):  
Tieshu Fan ◽  
Kamran Behdinan
Keyword(s):  
Cross Section ◽  
Separation Of Variables ◽  
Reaction Force ◽  
Squeeze Film ◽  
Test Rig ◽  
Damping Force ◽  
Squeeze Film Damper ◽  
Flow Equations ◽  
Pressure Region ◽  
Simulation And Experiment

In this paper, the effect of a circumferential central groove on an open-ended squeeze film damper is analytically investigated. Flow equations in both the central groove and film land are solved by applying the technique of separation of variables. Model validation is presented by a rotor-squeeze film damper test rig using a recorded squeeze film damper film pressure, where a significant improvement from a classical squeeze film damper model is shown. It is found that the central groove has a high and stable pressure region while neglecting the groove effect that would over-estimate the damping force. Both simulation and experiment show that the increase of supply flow escalates the damper pressure and it could possibly avoid the film cavitation, thus raising the squeeze film damper reaction force. In addition, the effects of different groove cross-section shapes including rectangle, square, semi-circle, and semi-ellipse are evaluated. Model sensitivity shows that the size of the central groove has more impact on the damper performance than the shape of the groove.

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.

Validation of a squeeze-film-damper test rig by using multibody cosimulation

2014 ◽  
Vol 34 (3) ◽  
pp. 243-257 ◽  
Author(s):  
Steffen Jäger ◽  
Sabrina Vogel
Keyword(s):  
Squeeze Film ◽  
Test Rig ◽  
Squeeze Film Damper

Forced Response of a Squeeze Film Damper and Identification of Force Coefficients From Large Orbital Motions

2004 ◽  
Vol 126 (2) ◽  
pp. 292-300 ◽  
Author(s):  
Luis San Andre´s ◽  
Oscar De Santiago
Keyword(s):  
Excitation Frequency ◽  
Air Entrainment ◽  
Forced Response ◽  
Effective Length ◽  
Single Frequency ◽  
Squeeze Film ◽  
Inertia Force ◽  
Damping Force ◽  
Squeeze Film Damper ◽  
Force Coefficients

Experimentally derived damping and inertia force coefficients from a test squeeze film damper for various dynamic load conditions are reported. Shakers exert single frequency loads and induce circular and elliptical orbits of increasing amplitudes. Measurements of the applied loads, bearing displacements and accelerations permit the identification of force coefficients for operation at three whirl frequencies (40, 50, and 60 Hz) and increasing lubricant temperatures. Measurements of film pressures reveal an early onset of air ingestion. Identified damping force coefficients agree well with predictions based on the short length bearing model only if an effective damper length is used. A published two-phase flow model for air entrainment allows the prediction of the effective damper length, and which ranges from 82% to 78% of the damper physical length as the whirl excitation frequency increases. Justifications for the effective length or reduced (flow) viscosity follow from the small through flow rate, not large enough to offset the dynamic volume changes. The measurements and analysis thus show the pervasiveness of air entrainment, whose effect increases with the amplitude and frequency of the dynamic journal motions. Identified inertia coefficients are approximately twice as large as those derived from classical theory.

Squeeze Film Damper With a Mechanical End Seal: Experimental Force Coefficients Derived From Circular Centered Orbits

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Luis San Andrés ◽  
Adolfo Delgado
Keyword(s):  
Dry Friction ◽  
Dynamic Pressure ◽  
Test System ◽  
Single Frequency ◽  
Squeeze Film ◽  
Mechanical Seal ◽  
Damping Force ◽  
Squeeze Film Damper ◽  
Force Coefficients ◽  
Aircraft Application

The paper presents parameter identification measurements conducted on a squeeze film damper (SFD) featuring a nonrotating mechanical seal that effectively eliminates lubricant side leakage. The SFD-seal arrangement generates dissipative forces due to viscous and dry-friction effects from the lubricant film and surfaces in contact, respectively. The test damper reproduces an aircraft application that must contain the lubricant for extended periods of time. The test damper journal is 2.54cm in length and 12.7cm in diameter, with a nominal clearance of 0.127mm. The damper feed end opens to a plenum filled with lubricant, and at its discharge grooved section, four orifice ports evacuate the lubricant. In earlier publications, single frequency force excitation tests were conducted, without and with lubricant in the squeeze film land, to determine the seal dry-friction force and viscous damping force coefficients. Presently, further measurements are conducted to identify the test system and SFD force coefficients using two sets of flow restrictor orifice sizes (2.8mm and 1.1mm in diameter). The flow restrictors regulate the discharge flow area and thus control the oil flow through the squeeze film. The experiments also include measurements of dynamic pressures at the squeeze film land and at the discharge groove. The magnitude of dynamic pressure in the squeeze film land is nearly identical for both sets of flow restrictors, and for small orbit radii, dynamic pressures in the discharge groove have peak values similar to those in the squeeze film land. The identified parameters include the test system damping and the individual contributions from the squeeze film, dry friction in the mechanical seal and structure remnant damping. The identified system damping coefficients are frequency and motion amplitude dependent due to the dry-friction interaction at the mechanical seal interface. Squeeze film force coefficients, damping and added mass, are in agreement with simple predictive formulas for an uncavitated lubricant condition and are similar for both flow restrictor sizes. The SFD-mechanical seal arrangement effectively prevents air ingestion and entrapment and generates predicable force coefficients for the range of frequencies tested.

Experimental Investigation of Squeeze Film Damper Characteristics at High Speed Rotor Configurations

2014 ◽  
Author(s):  
Jayaraman Kandasamy ◽  
B. L. Jaiswal ◽  
P. Sarasu ◽  
S. Sivaperumal ◽  
Dilli Babu ◽  
...  
Keyword(s):  
High Speed ◽  
High Performance ◽  
Critical Speed ◽  
Advanced Materials ◽  
Squeeze Film ◽  
Test Rig ◽  
Variable Frequency Drive ◽  
Squeeze Film Damper ◽  
Essential Components ◽  
Turbo Machinery

High performance turbo machinery demands high shaft speeds, increased rotor flexibility, tighter clearances in flow passages, advanced materials, and increased tolerance to imbalances. Operation at high speeds induces severe dynamic loading with large amplitude journal motions at the bearing supports. Squeeze film dampers are essential components of high-speed turbo machinery since they offer the unique advantages of dissipation of vibration energy and isolation of structural components, as well as the capability to improve the dynamic stability characteristics of inherently unstable rotor-bearing systems. A bearing test rig is developed using 350 KW motor with variable frequency drive and has the potential of maximum operating speed up to 20,000 rpm. A squeeze film damper is used between the bearings and housing to reduce the unbalance forces transmitted to the pedestal by introducing an additional damping and thereby reduces the amplitude of vibration to acceptable level. The test rig instrumentation is capable of detecting bearing critical speed of the test rotor, and has been used for parametric studies and to monitor the temperature profile, vibration levels and pressure distribution of SFD oil film. The first critical speed of the test rotor is measured. The vibration level of the rotor system is increased with the rise of axial load together with speed. It is estimated that under all the conditions presence of oil in SFD zone reduces the vibration levels.

Identification of Force Coefficients in a Squeeze Film Damper With a Mechanical End Seal: Centered Circular Orbit Tests

2007 ◽  
Author(s):  
Luis San Andre´s ◽  
Adolfo Delgado
Keyword(s):  
Dry Friction ◽  
Dynamic Pressure ◽  
Test System ◽  
Single Frequency ◽  
Squeeze Film ◽  
Mechanical Seal ◽  
Damping Force ◽  
Squeeze Film Damper ◽  
Force Coefficients ◽  
Aircraft Application

The paper presents parameter identification measurements conducted on a squeeze film damper (SFD) featuring a non-rotating mechanical seal that effectively eliminates lubricant side leakage. The SFD-seal arrangement generates dissipative forces due to viscous and dry-friction effects from the lubricant film and surfaces in contact, respectively. The test damper reproduces an aircraft application that must contain the lubricant for extended periods of time. The test damper journal is 2.54 cm in length and 12.7 cm in diameter, with a nominal clearance of 0.127 mm. The damper feed end opens to a plenum filled with lubricant, and at its discharge grooved section, four orifice ports evacuate the lubricant. In prior publications (ASME Paper GT2006-90782, IJTC2006-12041), single frequency force excitation tests were conducted, without and with lubricant in the squeeze film land, to determine the seal dry-friction force and viscous damping force coefficients. Presently, further measurements are conducted to identify the test system and SFD force coefficients using two sets of flow restrictor orifice sizes (2.8 mm and 1.1 mm in diameter). The flow restrictors regulate the discharge flow area, and thus control the oil flow through the squeeze film. The experiments also include measurements of dynamic pressures at the squeeze film land and at the discharge groove. The magnitude of dynamic pressure in the squeeze film land is nearly identical for both sets of flow restrictors, and for small orbit radii, dynamic pressures in the discharge groove have peak values similar to those in the squeeze film land. The identified parameters include the test system damping and the individual contributions from the squeeze film, dry friction in the mechanical seal and structure remnant damping. The identified system damping coefficients are frequency and motion amplitude dependent due to the dry friction interaction at the mechanical seal interface. Squeeze film force coefficients, damping and added mass, are in agreement with simple predictive formulas for an uncavitated lubricant condition and are similar for both flow restrictor sizes. The SFD-mechanical seal arrangement effectively prevents air ingestion and entrapment and generates predicable force coefficients for the range of frequencies tested.

A System to Measure the Response of a High-Speed Rotor to a Sudden Imbalance

1981 ◽  
Author(s):  
R. J. Trippett
Keyword(s):  
High Speed ◽  
Dynamic Test ◽  
Data Acquisition System ◽  
Squeeze Film ◽  
Sudden Increase ◽  
Test Rig ◽  
Dynamic Data ◽  
Squeeze Film Damper ◽  
Rotor Dynamic ◽  
Dynamic Data Acquisition

A unique rotor dynamic data acquisition system is described to control the gathering and display of rotor displacement data measured at rotor speeds up to 70 000 r/min. The first published results measured with this system are demonstrated with plots of measured transient shaft motion after a sudden increase in shaft imbalance at speeds up to 44 500 r/min. The displacements of the rotor in the forms of Lissajous plots with and without a squeeze film damper are presented at four axial shaft locations below and above the shafts critical speeds. The blade-loss, dynamic test rig is also described.

Experimental Investigation on the Dynamic Pressure and Force Response of a Partially Sealed Squeeze Film Damper

1991 ◽  
Author(s):  
G. Meng ◽  
L. A. San Andres ◽  
J. M. Vance
Keyword(s):  
Rotational Speed ◽  
Dynamic Pressure ◽  
Tangential Force ◽  
Radial Force ◽  
Squeeze Film ◽  
Damping Force ◽  
Film Pressure ◽  
Squeeze Film Damper ◽  
Fluid Forces ◽  
Supply Pressure

Abstract The influence of rotational speed, oil temperature and supply pressure on the squeeze film pressure and fluid forces is investigated experimentally for a partially sealed squeeze film damper (SFD) test rig executing circular centered orbits. Experimental Tesults show that the sealed damper produces higher damping forces than an open end SFD, though it is more prone to produce oil cavitation. As a result, the peak-to-peak pressures and the tangential force (damping force) decrease with increasing rotational speed; while, the radial force (stiffhening force) becomes negative due to the large extent of the cavitation zone. The tangential force decreases and the radial force increases with increasing lubricant temperature. The squeeze film pressure and film force increase as the supply pressure rises. The film cavitation onset is determined by the level of supply pressure and rotational speed.

Experimental research on suppressing unbalanced vibration of rotor by integral squeeze film damper

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Wei Yan ◽  
Lidong He ◽  
Zhe Deng ◽  
Xingyun Jia
Keyword(s):  
Rotational Speed ◽  
Critical Speed ◽  
Structural Characteristics ◽  
Experimental Studies ◽  
Rotor System ◽  
Squeeze Film ◽  
Rigid Rotor ◽  
Flexible Rotor ◽  
Test Rig ◽  
Squeeze Film Damper

Abstract As a novel structural damper, the unique structural characteristics of the integral squeeze film damper (ISFD) solve the nonlinear problem of the traditional squeeze film damper (SFD), and it has good linear damping characteristics. In this research, the experimental studies of ISFD vibration reduction performance are carried out for various working conditions of unbalanced rotors. Two ball bearing-rotor system test rigs are built based on ISFD: a rigid rotor test rig and a flexible rotor test rig. When the rotational speed of rigid rotor is 1500 rpm, ISFD can reduce the amplitude of the rotor by 41.79%. Under different unbalance conditions, ISFD can effectively improve the different degrees of unbalanced faults in the rotor system, reduce the amplitude by 43.21%, and reduce the sensitivity of the rotor to unbalance. Under different rotational speed conditions, ISFD can effectively suppress the unbalanced vibration of rigid rotor, and the amplitude can be reduced by 53.51%. In the experiment of the unbalanced response of the flexible rotor, it is found that ISFD can improve the damping of the rotor system, effectively suppress the resonance of the rotor at the critical speed, and the amplitude at the first-order critical speed can be reduced by 31.72%.

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.

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