Squeeze Film Damper Research Articles

The Impact of Squeeze Film Damper and Support Nonlinear Forces on the Dynamic Response of High-Speed Flexible Rotors

To investigate the nonlinear dynamic response of rotor systems, a finite element model of the squeeze film damper-rotor system was established. With the Euler–Bernoulli beam rotor model, the nonlinear oil film forces of the squeeze film damper (SFD) and the nonlinear restoring forces of the supports are applied as external loads to the support nodes using the finite element method. The Newmark Beta method was used to solve it, and the nonlinear dynamic response of the rotor was analyzed using frequency–response curves, time-domain response diagrams, and shaft centerline trajectory diagrams. The effects of different oil film gaps and support restoring force coefficients on the rotor response were examined. The results show that the coupling effect of the two nonlinear forces is the superposition of their individual effects; the two nonlinear forces have a significant impact on the rotor response amplitude, and appropriate parameter selection and installation positions can reduce the amplitude by 19%; and finally, among the two nonlinear forces, the SFD nonlinear oil film force mainly affects the amplitude, while the support nonlinear restoring force affects both the amplitude and frequency.

Co-Axial Rotor Aero-Engine System: A Hybrid Modelling and Dynamic in Situ Residual Balancing between High and Small Frequencies along Simulated Trial Unbalances with Active Magnetic Bearing Integration

Abstract Imbalance is a synchronous vibration and is observed at the 1x (synchronous vibration). In this study, the dynamic in-field balancing of the co-axial rotor aero-engine system, that is, the estimation of the residual imbalance, is considered with the active magnetic bearing (AMB) integration. AMB devices are built with a feedback control algorithm with a PID control. The improved influence coefficient method (IICM) is used to identify imbalance forces in low and high-pressure rotors simultaneously through simulated trial unbalance from AMB magnetic excitation. To estimate the imbalances using IICM, the system's vibratory responses in the limited regions and the simulated trial unbalances' phase and magnitudes are only needed. The coaxial-rotor system's differential equation and dynamic model are established with a squeeze-film damper (SFD) at a low-pressure rotor using force coefficients in linear form. A flexible roller bearing, including an inter-shaft flexible bearing (IFB), supports the high-pressure rotor at both ends accordingly. For a mathematical model, the displacement response from a co-axial rotor aero-engine with discrete unbalances for multi-disk and multi-plane configurations is established to illustrate the proposed technique by a FEM. To validate the proposed technique, a specific percentage from measurement noises is considered while estimating the residual imbalances. It is found that the co-axial rotor system can smoothly cross its critical speed with minimal vibrational response upon balancing.

Dynamic Characteristics and Periodic Stability Analysis of Rotor System with Squeeze Film Damper Under Base Motions

Inertial loads induced by base motion excitation introduce significant complexities in equilibrium point determination and linearization of systems incorporating squeeze film dampers (SFDs). The coupled effects of base motion excitation and SFD characteristics on periodic stability have received limited attention in previous investigations. This study investigates the dynamic characteristics and periodic stability of a rotor system with SFD subjected to base motion excitation. A finite element model of the rotor-SFD-support system under non-inertial motion is established. The periodic responses are solved using the harmonic balance method with alternating frequency/time technique (HB-AFT) and the arc-length continuation algorithm incorporating the predictor–corrector method, while system stability is analyzed using Floquet theory and the Newmark method. A systematic parametric study is conducted to investigate the effects of base motion parameters, mass unbalance, and SFD parameters on the system’s periodic response. Results demonstrate that base pitching motion enhances system stability, suppresses bistable responses and jump phenomena, and reduces unstable vibration regions. However, under specific parameter combinations, pitching motion can trigger secondary Hopf bifurcations, leading to quasi-periodic and chaotic motions, among other complex nonlinear behaviors. This research provides theoretical foundations for stability-oriented design optimization of rotor systems with SFDs under base motion excitation.

Research on vibration damping of integral squeeze film damper based on fan rotor tester of turbofan

Research on vibration damping of integral squeeze film damper based on fan rotor tester of turbofan

Effect of Piston Ring Grooves on the Radial and Tangential Forces of a Squeeze Film Damper

Abstract Squeeze film dampers (SFDs) are components of rotating machinery used to reduce vibration amplitudes and improve the rotor dynamic stability. Piston rings (PRs) are often employed as end seals for SFDs. They enhance the damping forces while remaining limited to a small axial length. Piston rings are installed in grooves whose dimensions (width and depth) are generally one order of magnitude larger than the radial clearance of the SFD. The radial and axial clearances after the PR are mounted may impact the forces generated by the SFD to the point that they have to be considered as design parameters. Computational fluid dynamics (CFD) and bulk flow (BF) approaches were used to determine the impact of the axial and radial clearances introduced by the presence of the PRs. CFD is an accurate, direct approach to the problem but it requires intensive computational resources. Therefore, BF-based methods are considered as an appropriate option for a wide range of SFD operating conditions. The BF approach developed previously is now extended to include the PR clearances. The results are validated using CFD simulations for a simplified SFD geometry. This comparison underlines the strengths and limits of the BF approach. The impact of the PR clearances on the radial and tangential forces is then evaluated on a realistic SFD by using the BF model. A parametric study is conducted to explore the impact of varying the axial and radial PR clearances. Overall, a procedure for correctly considering PR clearances in a BF framework is proposed and validated, while complementary elements for understanding the role of PR clearances are described.

Dynamic Response of A Pivot-Mounted Squeeze Film Damper: Measurements and Predictions

Abstract Squeeze film dampers (SFDs) are widely used to reduce vibration levels in rotating equipment. These devices are installed in series with bearings and are subjected to precessional motions with the inner and outer damper surfaces remaining parallel. Alternatively, this paper evaluates the dynamic performance of a damper describing angular motions. This paper includes the design and development of a test rig, and the experimental dynamic response of the pivot-mounted journal benchmarked with a predictive finite element code. The experimental setup uses a housing with two different radial clearances$3 mils (76.2 µm) for the lower land and 12 mils (304.8 µm) for the upper land$which is open to atmosphere. This work also includes developing a pivot-mounted SFD computer code, capable of predicting the dynamic performance of unpressurized 2p and segmented dampers. The numerical tool can predict the dynamic performance of a damper that has multiple land diameters with different clearances. The experimental results identify stiffness, damping, and added mass for both the SFD and its structure, showing a close correlation with the numerical calculations using three different fluid viscosities.

Inner race dynamics of a high-speed ball bearing with elastic ring squeeze film damper

Abstract This paper aims at the inner race dynamics of a high-speed ball bearing incorporated with Elastic Ring Squeeze Film Damper (ERSFD). Dynamic model of the inner race with three degrees of freedom (DOFs) is established in an ERSFD integrated ball bearing. Ball contact force and operating contact angle are characterized through an improved quasi-static model where the geometric relationship between the bearing displacement and elastic deformation is developed by considering the outer race movement. Numerical simulations were performed for bearings with or without ERSFD. The model was validated using Campbell diagram, measured displacement response and center trajectory of the inner race at different rotor speeds. The results show that the ERSFD provides adequate stable traction on the ball and limits excessive increase in the inner race contact angle. Such load-carrying condition benefits for decrease in ball orbital revolution skid at high rotor speeds. The ERSFD helps rotor unbalance force dominate bearing motion, leading to a stable periodic motion for the inner race at high rotor speeds. For ball bearings without ERSFD inner race possess stable motion at low and moderate rotor speeds, but is more prone to instability at high rotor speeds.

Identification of the rotor dynamic coefficient of a squeeze film damper with dilatant fluid

Dilatant fluids exhibit a sudden increase in viscosity when the shear rate increases. This characteristic can be used in the design of bearings that can suppress vibrations in the event of a sudden increase in shear rate, such as in rotating machinery. The bearings for rotating machines are designed based on a model that uses dynamic coefficients of the rotor. Therefore, in this study, the bearing coefficients of a squeeze film damper (SFD) using a dilatant fluid were experimentally determined. These characteristics were compared with those of a typical SFD using oil.

Measurement of Steam-Generator-Tube Vibration Damping Caused by Anti-Vibration-Bar Supports

Abstract In 2013, Atomic Energy of Canada Limited (now Canadian Nuclear Laboratories) experimentally measured the damping of a straight tube with a variety of tube supports to examine low-frequency damping. These tests were motivated by the discovery of severe tube damage caused by in-plane fluidelastic instability (FEI) in the U-bend regions of new replacement recirculating steam generators (SG). The measurements were intended to assess the applicability of existing design guidelines for estimating the support-related damping of a tube. In the tests, the damping ratios of a single steam generator tube were measured using both log-decrement and power-based methods. Noncontacting excitation and position-sensing techniques were employed to improve accuracy. Initial baseline tests explored configurations with no support and drilled-hole supports of different hole sizes, and these results were compared with previously published work. Subsequent tests were performed to measure damping of tube vibration parallel to flat-bar supports. Most of the tests were performed with the tube fully submerged in still water. The tests examined the effects of fluid (water or air), natural frequency, gap width, preload, and vibration normal to the bars. This paper describes the test apparatus, methods, and analysis techniques. A summary of the results is presented. The initial baseline results showed that the damping ratios measured without any supports and with a drilled-hole support were consistent with previously published data. However, the subsequent measurements showed that, contrary to a published design guideline, the anti-vibration bars resulted in no significant additional viscous or squeeze-film damping when the vibration was parallel to the bars. On the other hand, the results did show that anti-vibration bars could introduce significant in-plane Coulomb-type damping if there was sufficient tube-to-support preload or impacting.

Dynamic modeling and response analysis of misaligned rotor system with squeeze film dampers under maneuver loads

Dynamic modeling and response analysis of misaligned rotor system with squeeze film dampers under maneuver loads

Bifurcation and dynamics of periodic solutions of MEMS model with squeeze film damping

Bifurcation and dynamics of periodic solutions of MEMS model with squeeze film damping

Analytical model of curvic coupling and application in nonlinear vibration analysis of a squeeze film damper - rolling bearing - rotor system

Analytical model of curvic coupling and application in nonlinear vibration analysis of a squeeze film damper - rolling bearing - rotor system

Monolithic finite element modeling of compressible fluid‐structure‐electrostatics interactions in MEMS devices

AbstractThis work presents a monolithic finite element strategy for the accurate solution of strongly‐coupled fluid‐structure‐electrostatics interaction problems involving a compressible fluid. The complete set of equations for a compressible fluid is employed within the framework of the arbitrary Lagrangian–Eulerian (ALE) fluid formulation on the reference configuration. The proposed numerical approach incorporates geometric nonlinearities of both the structural and fluid domains, and can thus be used for investigating dynamic pull‐in phenomena and squeeze film damping in high aspect‐ratio micro‐electro‐mechanical systems (MEMS) structures immersed in a compressible fluid. Through various illustrative examples, we demonstrate the significant influence of fluid compressibility on the dynamics of MEMS devices subjected to constrained geometry and/or high‐frequency electrostatic actuation. Moreover, we compare the proposed formulation with the nonlinear compressible Reynolds equation and highlight that, particularly at low pressures and high fluid viscosity, the Reynolds equation fails to provide a reliable approximation to the complete set of equations utilized in our proposed formulation.

Experimental Study on Vibration and Noise Reduction of Gear Transmission System Based on ISFD

Gear transmission systems are widely used in ship propulsion systems, but, during operations, they produce serious vibration and noise problems, reducing the fatigue life of gears and affecting the performance of ships and the comfort of operators. Taking into account the complex frequencies and vibration components of gear transmission systems, this study conducted wide-band vibration suppression and noise reduction research on a gear transmission system using an integral squeeze film damper (ISFD), providing a novel approach for reducing vibration and noise in gear transmission systems. By conducting a simulation analysis and numerical calculations, the ISFD was analyzed via a static analysis and a dynamic analysis. We developed an experimental platform for reducing vibration and noise in gear transmission systems using sliding bearings, and the experiments were conducted under different speed and load conditions to study the vibration suppression and noise reduction of gears based on the ISFD. The experimental results show that the ISFD has good vibration suppression capabilities for gears at different speeds, with a horizontal vibration reduction of 75.44% and a vertical vibration reduction of 68.48% at 2400 r/min. The ISFD has wide-band vibration suppression capabilities, especially for mesh frequency and twice-mesh frequency, with a vibration reduction of 86.96% or more. Moreover, the ISFD has good vibration suppression capabilities for gears at different load torques, with a reduction of more than 35% in all directions. In addition, the ISFD also has noise reduction capabilities, reducing the gears’ noise by 1.92 dB at different speeds.

Influence of Squeeze Film Damper on the Rub-Impact Response of a Dual-Rotor Model

Influence of Squeeze Film Damper on the Rub-Impact Response of a Dual-Rotor Model

Tilt effect on squeeze-film damping in electrostatic micro-actuators

Tilt effect on squeeze-film damping in electrostatic micro-actuators

Exploiting Nonlinearities of Electrostatic MEMS Resonators for Tunable Low Pressure Sensing

In this paper, we demonstrate the potential functionalization of inherent nonlinearities associated with electrostatic MEMS resonators for low air pressure applications, with operating ranges as low as 0.65-295 mbar. The proposed pressure sensor is made of a polysilicon microplate subject to electrostatic actuation via an underneath electrode and attached to two cantilever microbeams. The pressure sensing mechanism relies on the motion-induced current method, a transduction mechanism that converts the dynamic alteration of the microplate due to pressure variations into an electrical signal detected via a lock-in amplifier. The experimental study showed evidence of the possible tunability of the pressure sensor via the deployment of different detection mechanisms to achieve superior performance in terms of sensitivity and low pressure operating range. These mechanisms rely on nonlinear dynamic features that result from the strong coupling between the microplate and the surrounding fluid along with the electrostatic actuation. These include dynamic pull-in instability, bifurcation and softening behavior associated with the elastic effect of the squeeze-film damping. The experimental results revealed that tracking the bifurcation frequency allows for the detection of low pressure levels, in the range of a few millibars. This capability is not provided by the resonance frequency shift method, which, while offering higher sensitivity, does not achieve the same low-pressure detection.

A MEMS resonant vacuum gauge for high vacuum measurement

A MEMS resonant vacuum gauge for high vacuum measurement

Vibration stability and bifurcation analysis of two-stage spur gear systems supported by squeeze film dampers

Vibration stability and bifurcation analysis of two-stage spur gear systems supported by squeeze film dampers

Simulation Analysis of Non-concentric Squeeze Film Damper

Squeeze film dampers are components that provide additional damping for rotating motors. In general, in order to achieve the best results of the squeeze film damper, it is necessary to appropriately increase the damping value, reduce the stiffness and set a reasonable eccentricity. In the process of designing the squeeze film damper, we can apply the rotor dynamics module of COMSOL software to model and simulate it, so as to achieve better simulation results and lay a foundation for the subsequent development and design of the product. In COMSOL software, in order to simplify the modeling of rotor components, we usually model squeeze film dampers based on the damping coefficient. The model calculates the damping coefficient for a short squeeze film damper and compares the results with the analytically calculated values. In addition, the damping coefficient depends on the position of the journal in the damper, i.e., the magnitude of the eccentricity. In this paper, by analyzing the dimensionless damping coefficient, bearing stiffness, journal displacement, and fluid load at different eccentricity, and plotting the fluid pressure distribution and the average oil film flow rate of the squeeze film damper, we can find the most suitable range of eccentricity and the damage-prone part of the damper, which can provide an important reference for the actual design of the squeeze film damper.