Effect of a Circumferential Feeding Groove on the Dynamic Force Response of a Short Squeeze Film Damper

1994 ◽  
Vol 116 (2) ◽  
pp. 369-376 ◽  
Author(s):  
G. L. Arauz ◽  
L. San Andres
Keyword(s):  
Flow Model ◽  
Dynamic Pressure ◽  
Squeeze Film ◽  
Dynamic Force ◽  
Force Response ◽  
Squeeze Film Damper ◽  
Circumferential Groove ◽  
Damping Characteristics ◽  
Radial Forces ◽  
Lubricant Viscosity

The effect of a circumferential feeding groove on the dynamic force response of a short length, open end squeeze film damper is studied experimentally. Damper configurations with increasing groove depths and journal orbit radii were tested for several conditions of whirl frequency and lubricant viscosity. Significant levels of dynamic pressure were measured at the circumferential groove, and relatively large tangential (damping) forces are produced at the groove which contribute considerably to the damping characteristics of the SFD test articles. Radial forces of substantial magnitude are determined at the groove and at the thin film land where the squeeze film Reynolds number is typically less than 1. The circumferential groove is thought to induce an inertia like effect into the film land. The experimental results correlate well with the predictions from a groove volume-circumferential flow model developed.

Experimental Study on the Effect of a Circumferential Feeding Groove on the Dynamic Force Response of a Sealed Squeeze Film Damper

1996 ◽  
Vol 118 (4) ◽  
pp. 900-905 ◽  
Author(s):  
G. L. Arauz ◽  
Luis San Andres
Keyword(s):  
Piston Ring ◽  
Dynamic Pressure ◽  
Squeeze Film ◽  
Dynamic Force ◽  
Force Response ◽  
Flow Conditions ◽  
Squeeze Film Damper ◽  
Circumferential Groove ◽  
Damping Characteristics ◽  
Radial Forces

The influence of a circumferential feeding groove on the dynamic force response of a sealed squeeze film damper is determined experimentally. The damper is sealed by means of a serrated piston ring located at the discharge end of the damper. Damper configurations with two different groove depths and journal orbit radii were tested at increasing whirl frequencies. Large levels of dynamic pressure were measured at the circumferential groove, and relatively large tangential (damping) forces are produced at the groove which contribute considerably to the damping characteristics of the test damper. Radial forces were also determined at the feeding groove and at the film land for uncavitated flow conditions.

scholarly journals Dynamic Force Response of an Open Ended Squeeze Film Damper

1991 ◽  
Author(s):  
L. A. San Andres ◽  
G. Meng ◽  
S. Yoon
Keyword(s):  
Pressure Field ◽  
Tangential Force ◽  
Radial Force ◽  
Squeeze Film ◽  
Dynamic Force ◽  
Flow Conditions ◽  
Squeeze Film Damper ◽  
Inertial Flow ◽  
Experimental Pressure ◽  
Lubricant Viscosity

The effects of whirl frequency and lubricant viscosity on the experimental pressure field and film forces in an open ended squeeze film damper test rig are presented. The measurements refer to circular centered journal motion of amplitude equal to one half the damper clearance (ε=0.5). The whirl frequency varied between 16Hz to 85Hz, while the lubricant temperature increased from 25°C to 45°C. The damper operated with levels of external pressurization which supressed lubricant cavitation. The experimental results show conclusivey that the radial film force is purely an inertial effect, i.e. it depends solely on the fluid density and the second power of the whirl frequency. The tangential film force shows a variation which depends on the viscous and inertial flow conditions in the squeeze film region. Correlation of experimental forces with conventional SFD models shows the radial force to be π times larger than the theoretical prediction, while the tangential force correlates well for low whirl frequencies and large lubricant viscosities.

Dynamic Force Response of an Open-Ended Squeeze Film Damper

1993 ◽  
Vol 115 (2) ◽  
pp. 341-346 ◽  
Author(s):  
L. A. San Andres ◽  
G. Meng ◽  
S. Yoon
Keyword(s):  
Pressure Field ◽  
Tangential Force ◽  
Radial Force ◽  
Squeeze Film ◽  
Dynamic Force ◽  
Flow Conditions ◽  
Squeeze Film Damper ◽  
Inertial Flow ◽  
Experimental Pressure ◽  
Lubricant Viscosity

The effects of whirl frequency and lubricant viscosity on the experimental pressure field and film forces in an open-ended squeeze film damper test rig are presented. The measurements refer to circular centered journal motion of amplitude equal to one half the damper clearance (ε = 0.5). The whirl frequency varied between 16 Hz and 85 Hz, while the lubricant temperature increased from 25°C to 45°C. The damper operated with levels of external pressurization that supressed lubricant cavitation. The experimental results show conclusively that the radial film force is purely an inertial effect, i.e., it depends solely on the fluid density and the second power of the whirl frequency. The tangential film force shows a variation that depends on the viscous and inertial flow conditions in the squeeze film region. Correlation of experimental forces with conventional SFD models shows the radial force to be π times larger than the theoretical prediction, while the tangential force correlates well for low whirl frequencies and large lubricant viscosities.

On the Experimental Dynamic Force Performance of a Squeeze Film Damper Supplied Through a Check Valve and Sealed With O-Rings

2021 ◽  
Author(s):  
Luis San Andrés ◽  
Bryan Rodríguez
Keyword(s):  
Dynamic Pressure ◽  
Excitation Frequency ◽  
Check Valve ◽  
Forced Response ◽  
Single Frequency ◽  
Squeeze Film ◽  
Dynamic Force ◽  
Viscous Damping ◽  
Test Rig ◽  
Force Coefficients

Abstract In rotor-bearing systems, squeeze film dampers (SFDs) assist to reduce vibration amplitudes while traversing a critical speed and also offer a means to suppress rotor instabilities. Along with an elastic support element, SFDs are effective means to isolate a rotor from its casing. O-rings (ORs), piston rings (PRs) and side plates as end seals reduce leakage and air ingestion while amplifying the viscous damping in configurations with limited physical space. ORs also add a centering stiffness and damping to a SFD. The paper presents experiments to quantify the dynamic forced response of an O-rings sealed ends SFD (OR-SFD) lubricated with ISO VG2 oil supplied at a low pressure (0.7 bar(g)). The damper is 127 mm in diameter (D), short in axial length L = 0.2D, and the film clearance c = 0.279 mm. The lubricant flows into the film land through a mechanical check valve and exits through a single port. Upstream of the check valve, a large plenum filled with oil serves to attenuate dynamic pressure disturbances. Multiple sets of single-frequency dynamic loads, 10 Hz to 120 Hz, produce circular centered orbits with amplitudes r = 0.1c, 0.15c and 0.2c. The experimental results identify the test rig structure, ORs and SFD force coefficients; namely stiffness (K), mass (M) and viscous damping (C). The ORs coefficients are frequency independent and show a sizeable direct stiffness, KOR ∼ 50% of the test rig structure stiffness, along with a quadrature stiffness, K0∼0.26 KOR, demonstrative of material damping. The lubricated system damping coefficient equals CL = (CSFD + COR); the ORs contributing 10% to the total. The experimental SFD damping and inertia coefficients are large in physical magnitude; CSFD slightly grows with orbit size whereas MSFD is relatively constant. The added mass (MSFD) is approximately four-fold the bearing cartridge mass; hence, the test rig natural frequency drops by ∼50% once lubricated. A computational physics model predicts force coefficients that are just 10% lower than those estimated from experiments. The amplitude of measured dynamic pressures upstream of the plenum increases with excitation frequency. Unsuspectedly, during dynamic load operation, the check valve did allow for lubricant backflow into the plenum. Post-tests verification demonstrates that, under static pressure conditions, the check valve does work since it allows fluid flow in just one direction.

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.

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.

Experimental Measurement of the Dynamic Force Response of a Squeeze-Film Bearing Damper

1975 ◽  
Vol 97 (4) ◽  
pp. 1282-1290 ◽  
Author(s):  
John M. Vance ◽  
Alan J. Kirton
Keyword(s):  
Pressure Distribution ◽  
Taylor Vortex ◽  
Squeeze Film ◽  
Dynamic Force ◽  
Force Response ◽  
Cyclic Flow ◽  
Pressure Distributions ◽  
Taylor Vortex Flow ◽  
Force Components ◽  
Annular Clearance

An experimental study of the hydrodynamic force response of a squeeze-film bearing damper with end seals was carried out. Measurements of the pressure distribution about a journal constrained to move in a circular orbit were made for the journal orbit centered in the annular clearance and offset from the center of the annular clearance. The effects of cyclic flow in a radial inlet were studied for the case of the journal orbit centered in the annular clearance. For the off-center case the pressure distribution around the damper was measured for four different combinations of eccentricity, radial velocity, and angular velocity of the line of centers, chosen in such a way as to allow calculation of the four bearing coefficients defined by Tondl. The experimentally determined pressure distributions were numerically integrated to determine the force components of the squeeze film. The results are compared to the “long bearing” and the “short bearing” solutions of Reynolds’ equation. For the centered case, good agreement was found with the shape of the “long bearing” solution. Higher-than-predicted pressures and forces for light viscosity oil are explained by showing that this case is operating in the Taylor vortex flow regime. Similar calculations indicate that turbine dampers can also operate with vortex or turbulent flow.

On the Experimental Dynamic Force Performance of a Squeeze Film Damper Supplied Through a Check Valve and Sealed with O-Rings

2021 ◽  
Author(s):  
Luis San Andres ◽  
Bryan Rodríguez
Keyword(s):  
Dynamic Pressure ◽  
Effective Means ◽  
Check Valve ◽  
Physical Space ◽  
Forced Response ◽  
Squeeze Film ◽  
Dynamic Force ◽  
Viscous Damping ◽  
Frequency Independent ◽  
Support Element

Abstract In rotor-bearing systems, squeeze film dampers (SFDs) assist to reduce vibration amplitudes while traversing a critical speed and also offer a means to suppress rotor instabilities. Along with an elastic support element, SFDs are effective means to isolate a rotor from its casing. O-rings (ORs) reduce leakage and air ingestion while amplifying the viscous damping in configurations with limited physical space. ORs also add a centering stiffness and damping to a SFD. The paper presents experiments to quantify the dynamic forced response of an O-rings sealed ends SFD lubricated with ISO VG2 oil supplied at a low pressure. The lubricant flows into the film land through a mechanical check valve and exits through a single port. Upstream of the check valve, a large plenum filled with oil serves to attenuate dynamic pressure disturbances. The experimental results identify the test rig structure, ORs and SFD force coefficients; namely stiffness, mass and viscous damping. The ORs coefficients are frequency independent and show a sizeable direct stiffness along with a quadrature stiffness demonstrative of material damping. The experimental SFD damping and inertia coefficients are large in physical magnitude; CSFD slightly grows with orbit size whereas MSFD is relatively constant. The added mass (MSFD) is approximately four-fold the bearing cartridge mass. Unsuspectedly, during dynamic load operation, the check valve did allow for lubricant backflow into the plenum. Post-tests verification demonstrates that, under static pressure conditions, the check valve does work since it allows fluid flow in just one direction.

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