scholarly journals Study on the Vibration Mitigation Characteristic of Dual Clearance Squeeze Film Damper

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Zhaojun Feng ◽  
Guihuo Luo ◽  
Hai Yang ◽  
Wangqun Deng ◽  
Wei Chen ◽  
...  
Keyword(s):  
Excitation Frequency ◽  
Great Influence ◽  
Squeeze Film ◽  
Vibration Mitigation ◽  
Squeeze Film Damper ◽  
Response Characteristics ◽  
Pressure Loss Coefficient ◽  
Mass Eccentricity ◽  
Simulation And Experiment ◽  
Novel Model

In this paper, a novel model of dual clearance squeeze film damper (DCSFD) was constructed considering convection effect and the vibration mitigation characteristic of DCSFD was researched. The DCSFD film force linearity r FSFD was proposed. The response characteristics of rigid rotor containing DCSFD were studied based on the DCSFD model. A response experiment of the DCSFD was arranged, and the model was verified. A good consistence was achieved between the simulation and experiment. The experiment and simulation result manifests that the unbalance response of DCSFD was smaller than that of SFD at every excitation frequency. The DCSFD could inhibit the nonlinear vibration such as the bistability and bifurcation due to big mass eccentricity, and nonlinear film force for the DCSFD film force linearity was bigger than that for SFD. The thickness ratio of inner and outer film, pressure loss coefficient, and inner film thickness were the important parameters that have great influence on DCSFD vibration mitigation characteristic.

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.

Hermetically Sealed Squeeze Film Damper for Operation in Oil-Free Environments

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Bugra Ertas ◽  
Adolfo Delgado
Keyword(s):  
Excitation Frequency ◽  
Squeeze Film ◽  
Force Density ◽  
Viscous Damping ◽  
Squeeze Film Damper ◽  
Open Flow ◽  
Damping Coefficients ◽  
End Plate ◽  
Stiffness And Damping ◽  
Gas Bearing

The following work advances a new concept for a hermetically sealed squeeze film damper (HSFD), which does not require an open-flow lubrication system. The hermetically sealed concept utilizes a submersed plunger within a contained fluidic cavity filled with incompressible fluid and carefully controlled end plate clearances to generate high levels of viscous damping. Although the application space for a hermetic damper can be envisioned to be quite broad, the context here will target the use of this device as a rotordynamic bearing support damper in flexibly mounted gas bearing systems. The effort focused on identifying the stiffness and damping behavior of the damper while varying test parameters such as excitation frequency, vibration amplitude, and end plate clearance. To gain further insight to the damper behavior, key dynamic pressure measurements in the damper land were used for identifying the onset conditions for squeeze film cavitation. The HSFD performance is compared to existing gas bearing support dampers and a conventional open-flow squeeze film dampers (SFD) used in turbomachinery. The damper concept yields high viscous damping coefficients an order of magnitude larger than existing oil-free gas bearing supports dampers and shows comparable damping levels to current state of the art open-flow SFD. The force coefficients were shown to contribute frequency-dependent stiffness and damping coefficients while exhibiting amplitude independent behavior within operating regimes without cavitation. Finally, using experimentally based force density calculations, the data revealed threshold cavitation velocities, approximated for the three end seal clearance cases. To complement the experimental work, a Reynolds-based fluid flow model was developed and is compared to the HSFD damping and stiffness results.

scholarly journals Passive vibration reduction of a squeeze film damper for a rotor system with fit looseness between outer ring and housing

2020 ◽  
pp. 146134842096869
Author(s):  
Haifei Wang
Keyword(s):  
Nonlinear Vibration ◽  
Vibration Reduction ◽  
Research Work ◽  
Contact Problems ◽  
Rotor System ◽  
Outer Ring ◽  
Squeeze Film ◽  
Squeeze Film Damper ◽  
Response Characteristics ◽  
Vibration Responses

Clearances between bearing outer ring and sleeve can generally be maintained to provide a margin for the thermal expansion of the bearings. However, temperature variation, improper assembly and long-term vibration can enlarge the clearances and accelerate mechanical wear, leading to what is known as the fit looseness fault. Therefore, it is important to study a fit looseness fault model and investigate how to control the vibration coming from the fit looseness fault. In this paper, a Jeffcott rotor system with three disks was modeled as a single unit. A fit looseness model was applied in the whole rotor model to study the contact problems and response characteristics using a numerical integration method. Then, a squeeze film damper model was applied to assess the vibration reduction effects on the whole rotor system with the fit looseness fault. By comparing the results of the fit looseness fault without squeeze film damper and with squeeze film damper, it is found that the squeeze film damper can reduce nonlinear vibration responses effectively generated by the fit looseness fault for the nonlinear contact. This research work contributes to understanding the mechanism of fit looseness fault and controlling strong nonlinear vibration responses due to the fit clearances.

Hermetically Sealed Squeeze Film Damper for Operation in Oil-Free Environments

2018 ◽  
Author(s):  
Bugra Ertas ◽  
Adolfo Delgado
Keyword(s):  
Excitation Frequency ◽  
Squeeze Film ◽  
Force Density ◽  
Viscous Damping ◽  
Squeeze Film Damper ◽  
Open Flow ◽  
Damping Coefficients ◽  
End Plate ◽  
Stiffness And Damping ◽  
Gas Bearing

The following work advances a new concept for a hermetically sealed squeeze film damper (HSFD), which does not require an open-flow lubrication system. The hermetically sealed concept utilizes a submersed plunger within a contained fluidic cavity filled with incompressible fluid and carefully controlled end plate clearances to generate high levels of viscous damping. Although the application space for a hermetic damper can be envisioned to be quite broad, the context here will target the use of this device as a rotordynamic bearing support damper in flexibly mounted gas bearing systems. The effort focused on identifying the stiffness and damping behavior of the damper while varying test parameters such as excitation frequency, vibration amplitude, and end plate clearance. To gain further insight to the damper behavior, key dynamic pressure measurements in the damper land were used for identifying the onset conditions for squeeze film cavitation. The HSFD performance is compared to existing gas bearing support dampers and a conventional open-flow squeeze film dampers (SFD) used in turbomachinery. The damper concept yields high viscous damping coefficients an order of magnitude larger than existing oil-free gas bearing supports dampers and shows comparable damping levels to current state of the art open-flow SFD. The force coefficients were shown to contribute frequency dependent stiffness and damping coefficients while exhibiting amplitude independent behavior within operating regimes without cavitation. Finally, using experimentally based force density calculations the data revealed threshold cavitation velocities, approximated for the three end seal clearance cases. To complement the experimental work, a Reynolds based fluid flow model was developed and is compared to the HSFD damping and stiffness results.

Time Transient Analysis of Horizontal Rigid Rotor Supported With O-Ring Sealed Squeeze Film Damper

2013 ◽  
Author(s):  
Saeid Dousti ◽  
Timothy W. Dimond ◽  
Paul E. Allaire ◽  
Houston E. Wood
Keyword(s):  
Transient Analysis ◽  
Reynolds Equation ◽  
Equations Of Motion ◽  
Excitation Frequency ◽  
Numerical Data ◽  
Operating Conditions ◽  
Squeeze Film ◽  
Rigid Rotor ◽  
Squeeze Film Damper ◽  
Squeeze Film Dampers

This study addresses the nonlinear dynamic behavior of O-ring seals as the retaining spring in squeeze film dampers (SFDs). An analytical model is developed to predict the restoring and hysteresis forces of elastomer O-rings based on experimental and numerical data. This model takes into account the temperature softening and excitation frequency hardening effects in O-rings as well as the installation conditions in the form of radial and vertical preloads, σ and γ, respectively. Long bearing assumption is adopted for the solution of Reynolds equation. The equations of motion of horizontal unbalanced rigid rotor are derived, and a dimensional analysis is conducted on them. The numerical results substantiates the synchronizing effects of bearing parameter, B and vertical preload, γ, and the asynchronizing effects of O-ring parameter, O and radial preload, σ. It is shown that the variation of temperature and rotational speed as operating conditions influence the rotor response significantly.

Calibration of the Stiffness and Damping Characteristics of a Magnetorheological Fluid Long Squeeze Film Damper in Terms of Reynolds Number

2010 ◽  
Vol 224 (10) ◽  
pp. 2121-2128 ◽  
Author(s):  
H P Jagadish ◽  
L Ravikumar
Keyword(s):  
Magnetic Field ◽  
Reynolds Number ◽  
Excitation Frequency ◽  
Squeeze Film ◽  
Squeeze Film Damper ◽  
Damping Coefficients ◽  
Carrier Liquid ◽  
Damping Characteristics ◽  
Semi Solid ◽  
Stiffness And Damping

Magnetorheological (MR) fluids are suspensions of fine micron-sized magnetizable particles in a suitable carrier liquid. The rheological properties of the fluid can be controlled by application of a suitable magnetic field and can be used in a variety of applications where variable damping and stiffness characteristics are required, based on the requirements of the rotor dynamic system. In this work, the stiffness and damping characteristics of MR fluid long squeeze film damper operating at low eccentricity ratios are calibrated in terms of Reynolds number of the squeeze film for different clearance and L/D ratios. A theoretical constant magnetic field viscosity model is developed, based on the literature, and is subsequently used to evaluate the theoretical stiffness and damping coefficients, at a particular excitation frequency. The results indicate that the stiffness and damping coefficients decrease with increasing Reynolds number of the squeeze film and is found to be abysmally low, indicating that the flow has ceased and the film has solidified. This is in accordance with the literature that predicts the formation of chain-like semi-solid structures, restricting the flow, and consequently increasing the viscosity, under the influence of the magnetic field. This change in viscosity, in turn, influences the stiffness and damping coefficients and the Reynolds number of the squeeze film. The stiffness and damping coefficients are found to increase with decreasing clearance, increasing L/D ratio, and eccentricity ratio. The results of the investigation assist the designer in obtaining the stiffness and damping characteristics of the squeeze film damper based on the Reynolds number of the squeeze film. Conversely, the stiffness and damping characteristics of the squeeze film damper are calibrated in terms of the Reynolds number of the squeeze film for different damper configurations.

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.

Ball bearing turbocharger vibration management: application on high speed balancer

2020 ◽  
Vol 21 (6) ◽  
pp. 619
Author(s):  
Kostandin Gjika ◽  
Antoine Costeux ◽  
Gerry LaRue ◽  
John Wilson
Keyword(s):  
Dynamic Behavior ◽  
High Speed ◽  
Internal Combustion Engines ◽  
Ball Bearing ◽  
Squeeze Film ◽  
Design And Technology ◽  
Squeeze Film Damper ◽  
Damping Coefficients ◽  
Bearing Loads ◽  
Stiffness And Damping

Today's modern internal combustion engines are increasingly focused on downsizing, high fuel efficiency and low emissions, which requires appropriate design and technology of turbocharger bearing systems. Automotive turbochargers operate faster and with strong engine excitation; vibration management is becoming a challenge and manufacturers are increasingly focusing on the design of low vibration and high-performance balancing technology. This paper discusses the synchronous vibration management of the ball bearing cartridge turbocharger on high-speed balancer and it is a continuation of papers [1–3]. In a first step, the synchronous rotordynamics behavior is identified. A prediction code is developed to calculate the static and dynamic performance of “ball bearing cartridge-squeeze film damper”. The dynamic behavior of balls is modeled by a spring with stiffness calculated from Tedric Harris formulas and the damping is considered null. The squeeze film damper model is derived from the Osborne Reynolds equation for incompressible and synchronous fluid loading; the stiffness and damping coefficients are calculated assuming that the bearing is infinitely short, and the oil film pressure is modeled as a cavitated π film model. The stiffness and damping coefficients are integrated on a rotordynamics code and the bearing loads are calculated by converging with the bearing eccentricity ratio. In a second step, a finite element structural dynamics model is built for the system “turbocharger housing-high speed balancer fixture” and validated by experimental frequency response functions. In the last step, the rotating dynamic bearing loads on the squeeze film damper are coupled with transfer functions and the vibration on the housings is predicted. The vibration response under single and multi-plane unbalances correlates very well with test data from turbocharger unbalance masters. The prediction model allows a thorough understanding of ball bearing turbocharger vibration on a high speed balancer, thus optimizing the dynamic behavior of the “turbocharger-high speed balancer” structural system for better rotordynamics performance identification and selection of the appropriate balancing process at the development stage of the turbocharger.

scholarly journals Influence of Eccentricity and Angular Velocity on Force Effects on Rotor of Magnetorheological Damper

2018 ◽  
Vol 180 ◽  
pp. 02091
Author(s):  
Dominik Šedivý ◽  
Petr Ferfecki ◽  
Simona Fialová
Keyword(s):  
Magnetic Induction ◽  
Magnetorheological Damper ◽  
Squeeze Film ◽  
Fluid Viscosity ◽  
Squeeze Film Damper ◽  
Viscous Forces ◽  
Angular Velocities ◽  
Volume Method ◽  
Gap Width ◽  
Made In

This article presents the evaluation of force effects on squeeze film damper rotor. The rotor is placed eccentrically and its motion is translate-circular. The amplitude of rotor motion is smaller than its initial eccentricity. The force effects are calculated from pressure and viscous forces which were measured by using computational modeling. Damper was filled with magnetorheological fluid. Viscosity of this non-Newtonian fluid is given using Bingham rheology model. Yield stress is not constant and it is a function of magnetic induction which is described by many variables. The most important variables of magnetic induction are electric current and gap width between rotor and stator. The simulations were made in finite volume method based solver. The motion of the inner ring of squeeze film damper was carried out by dynamic mesh. Numerical solution was solved for five different initial eccentricities and angular velocities of rotor motion.

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