Theoretical and Experimental Study on the Performance of Hermetic Diaphragm Squeeze Film Dampers for Gas-Lubricated Bearings

Low damping characteristics have always been a key sticking points in the development of gas bearings.The application of squeeze film dampers can significantly improve the damping performance of gas lubricated bearings.This paper proposed a novel hermetic diaphragm squeeze film damper(HDSFD)for oil-free turbomachinery supported by gas lubricated bearings.Several types of HDSFDs with symmetrical structure were proposed for good damping performance.By considering the compressibility of the damper fluid,based on hydraulic fluid mechanics theory,a dynamic model of HDSFDs under medium is proposed,which successfully reflects the frequency dependence of force coefficients.Based on the dynamic model,the effects of damper fluid viscosity,bulk modulus of damper fluid,thickness of damper fluid film and plunger thickness on the dynamic stiffness and damping of HDSFDs were analyzed.An experimental test rig was assembled and series of experimental studies on HDSFDs were conducted.The damper fluid transverse flow is added to the existing HDSFD concept,which aims to make the dynamic force coefficients independent of frequency.Although the force coefficient is still frequency dependent,the damping coefficient at high frequency excitation with damper fluid supply twice as that without damper fluid supply.The results serve as a benchmark for the calibration of analytical tools under development.

Research on a Rigid Rotor-Sliding Bearing System with a Squeeze Film Damper

In this paper, a dynamic model on a rigid rotor sliding bearing system with a SFD is established. The stability and bifurcation behaviors of the system are studied. On the basis of the differential equations of fluid momentum and mass continuity, the distribution pressure function is derived by taking oil film inertia force into consideration. Damping force, clearance excitation force, interference force of different frequencies and static load are also considered in the model. Finally, the governing equations of the stability and bifurcation behaviors of the system are solved by Floquet theory. Simulation of dynamic model shows that the rigid rotor sliding bearing system can maintain stability and exhibit a Hopf bifurcation phenomenon in a certain range.

Experimental Studies on Support Systems of High Speed Motors With Flexible Squirrel-cage Support and Squeeze Film Dampers

以100kW级工作转速为45000r／min的高速永磁同步电机为实验样机，对采用鼠笼式弹性支撑和挤油膜阻尼器的滚动轴承支撑系统进行研究。分析了弹性支撑和挤压油膜阻尼器的刚度和阻尼特性，在此基础上分别计算出刚性支撑和弹性阻尼支撑时轴承一转子系统的临界转速和瞬态动力特性。最后在样机上进行对比实验，并对电机机壳振动加速度和弹性支撑笼条微应变信号进行分析。结果表明，弹性阻尼支撑可以使转子以较低的转速通过其刚体模态，同时对转子的振动起到良好的抑制作用。实验样机稳定运行在设计工作转速，其分析和实验结果为高速电机轴系设计和动力学分析提供了参考。

STATIONARY DYNAMIC CHARACTERISTICS ANALYSIS OF NEW SQUEEZED FILM DAMPER

Recur to multi-hole and better elastic characteristics of metal rubber （MR）, a new squeezed film damper with MR （SFD/MR） throttle ring installed on the end of MR and MR damping ring installed on the radial direction of MR is implemented. Based on the D＇alembert principle, a locomotion equation and the mathematical model of stationary response of SFD/MR system is put forward. It proves that the SFD/MR has better ability to resist unbalance loads than the traditional SFD after the stationary dynamic characteristics of the traditional SFD and the new SFD/MR are researched.

Experimental study on vibration suppression in a rotor system under base excitation using an integral squeeze film damper

Base excitation is one of common excitations in rotor system.In order to study the dynamic characteristics of rotor systems under base excitation and the effect of integral squeeze film dampers(ISFDs)on their dynamic characteristics,a single-disk rotor test rig,where mass imbalance and base excitation could be applied,is developed.Experimental research on the rotor system response under sinusoidal base excitation conditions with different frequencies and excitation forces is performed and the effect of ISFD on the dynamic characteristics of the rotor is investigated.The experimental results demonstrate that when the sinusoidal base excitation frequency approaches the first critical speed of the rotor system or the natural frequency of the rotor system base,strong vibration occurs in the rotor,indicating that the base excitation of the two frequencies has a greater impact on rotor system response.In addition,with the increase of the base excitation force,the vibration of the rotor will be increased.ISFDs can significantly inhibit the vibration due to unbalanced forces and sinusoidal base excitation in rotor systems.To a certain extent,ISFDs can improve the effect of sinusoidal base excitation with most frequencies on rotor system response,and they have a good vibration reduction effect for sinusoidal base excitation with different excitation forces.

非稳态工况下外圈带有ERSFD的圆柱滚子轴承保持架动态特性

为降低航空发动机主轴传动系统的振动,通常将弹性环、挤压油膜阻尼器与圆柱滚子轴承联合使用。基于滚动轴承动力学理论和流体力学控制方程,建立了外圈带有弹性环式挤压油膜阻尼器(ERSFD)的圆柱滚子轴承动力学分析模型,采用GSTIFF预估-校正变步长积分法对动力学微分方程组进行求解,分析转速、冲击载荷以及弹性环结构参数(凸台宽度、凸台数量)对外圈带有ERSFD的圆柱滚子轴承保持架动态特性的影响,结果表明:外圈带有ERSFD的圆柱滚子轴承保持架稳定性高于普通圆柱滚子轴承;转速和冲击载荷对保持架动态特性影响较大,保持架打滑率随着转速的增大而增大,随着轴承所受冲击载荷的增大而减小;过大或过小的弹性环凸台数量与宽度都不利于圆柱滚子轴承保持架的稳定性,需要选择合适的凸台数量和宽度。

Numerical investigation on damping coefficient of the integral squeeze film damper

The elimination of rotor vibration is usually achieved by applying additional damping to the system.Squeeze film dampers are widely used in various aerospace and turbine equipments.The research is carried out on flow characteristics in the integral squeeze film dampers(ISFDs).The dynamic response to the operation condition is investigated through the computational fluid dynamics(CFD) model of ISFD.Due to the large pressure loss at the oil inlet,the oil film force only changes slightly with the increase of oil supply pressure,and the damping increases slightly.The vibration amplitude only affects the film force,but has no effect on the damping.The oil film force and damping show an upward tendency with the decrease of thickness of the end seal clearance.

Experimental study of suppressing the unbalanced response vibration of rotor system with a G-type integral squeeze film damper

Conventional squeeze film dampers have numerous challenges including lock up,bistable response and incoordinate precession.In order to resolve these nonlinear problems,a novel G-type integral squeeze film damper(GISFD)is proposed in this research.The experimental test rig is provided to investigate the rotor system with an unbalanced single disk.Numerical simulation results show that the structural design of GISFD is reasonable,which can ensure its safe and stable operation.The influence of different support stiffnesses on the first-order speed of the rotor system is analyzed.Experimental results show that GISFD can effectively suppress the unbalanced response vibration of the rotor.In a certain range,it is found that the suppression effect of GISFD increases with the increase in the kinematic viscosity of the damping fluid.When the silicone oil with kinematic viscosity coefficients v=30.0 cm^(2)/s is employed,the vibration reduction of GISFD is approximately 71.51%.Furthermore,the experimental results show that with the increase of the unbalance,there is a linear relationship between the unbalance and the corresponding amplitude of the unbalanced response.It is concluded that GISFD has excellent linear damping characteristics and reduces the sensitivity of the rotor system to the unbalanced mass.

Effect of integral squeeze film damper on vibration and noise of spur gear with center-distance error

When the actual installation center distance between a pair of spur gears is greater than the theoretical center distance,backlash increases,leading to increased vibration and noise.The structural parameters of an integral squeeze film damper(ISFD)were designed with the stiffness of rigid support as reference to investigate the effect of an ISFD on the dynamic characteristics of a spur gear transmission system with center-distance installation error.A spur gear test bench with center distance-error was built to investigate the vibration and noise reduction characteristics of ISFD.The experimental results indicate that,compared with a rigid support,the ISFD can reduce vibration by approximately 40%and noise by approximately 5 d B.ISFD can effectively absorb the impact energy caused by an increase of in backlash,which is conducive to the stable operation of the spur gear transmission system.

Optimization of a Flexible Rotor-Sliding Bearing System With a Squeeze Film Damper

A dynamic model of a flexible rotor-sliding bearing system ( FRSBS ) with asqueeze film damper ( SFD) is established. Considered in the model are oil film inertia force,damping farce, clearance excitation force, interference force of different frequencies and staticload, as opposed to previous research. On the basis of this model, the optimal design of the systemis deeply studied. Simulation shows that the system optimization design can effectively improve thesystem stability.

Chaotic Response of Cracked Rotor Supported on Squeeze Film Damper and the Routes to Chaos

In this paper, the chaotic response of a rotor system with crack supported on the squeeze film damper (SFD) is studied. Baesd on the short bearing approximation and π film assumption, the film force is expressed as a function of speed and displacement of the bearing in the X and Y directions. The result shows that the film force can suppress the non synchronous response effectively if an SFD is designed well. The increase of the bearing parameter can suppress chaos. When the bearing parameter is s...

A VARIABLE PARAMETER SQUEEZE OIL FILM DAMPER

The effectiveness of variable parameter squeeze oil film damper (VPSFD) in the steady and transient unbalance response control of flexible rotors is examined.First, a preliminary property design of VPSFD is presented on the improved finite length bearing theory.VPSFD is different from the conventional squeeze film damper, and is designed to possess continuous changeable oil film clearance and land length. These parameters can be exactly adjusted on a computer by sending commends to a special control device. Then, a simple rotor system with VPSFD is investigated. The experimental results show that VPSFD can attenuate the rotor system resonance peak due to unbalance.

Occurrence of bistable state in squeeze film damper rotor system

Presents the study on the law governing the occurrence of bistable state in the squeeze film damper supported rigid rotor system by theoretical calculations,the way q calculating the bistable state characteristics, the analysis of bistable state characteristics using bearing parameter B and mass eccentricity U as basic parameters, and the ranges of B and U values established, and concludes that the occurrence of bistable state can be avoided provided design parameters are properly selected so that the B and U values are not in the ranges established. This makes it convenient to optimize the squeeze film damper design parameters.

The Effect of Elastic Deformation in a New Style Elastic Squeeze Oil Film Damper on Its Vibration Absorption Characteristics

Squeeze oil film damper are widely used in small high-speed aeroengine.But they are all made of high-hardness alloy steel. In order to improve their vibration absorption performance a new style of soft metal plated damper has been studied. A coat of soft metal is plated on inner surface of the oil film ring, the surface will be deformed to some extent under the effect of oil film pressure. The characteristics of such dampers are calculated and analysed. Result shows that, compared with common damper, the new style damper can change oil film pressure distribution, enhance oil film damping, decrease stiffness, and reduce the force transfered to casing.

Experimental study on integral axial squeeze film damper to suppress longitudinal vibration of propulsion shafting

This paper aims at investigating the effectiveness of squeeze oil film in suppressing the longitudinal vibration of propulsion shaft systems through a novel integral axial squeeze film damper(IASFD).After designing the IASFD,a propulsion shafting test rig for the longitudinal vibration control is built.Longitudinal vibration control experiments of the propulsion shafting are carried out under different magnitude and frequency of the excitation force.The results show that both IASFD elastic support and IASFD elastic damping support have excellent vibration attenuation characteristics,and can effectively suppress the longitudinal vibration of the shaft system in a wide frequency range.However,IASFD elastic damping support has a more significant vibration reduction effect than the other supports,and increasing the damping of the system has obvious effect on reducing the shafting vibration.For an excitation force of 45 N,the maximum reduction of the vibration amplitude is 89.16%.Also,the vibration generated by the resonance phenomenon is also significantly reduced.

SOLUTION FOR PRESSURE DISTRIBUTION IN SQUEEZE FILM DAMPER WITH ELECTROHYDRAULIC ACTIVE CONTROL

Aiming at the problems existed in the squeeze film damper of the rotating machinery utilizing traditional passive dynamic pressure film bearing, a project of dynamic pressure and static pressure hybrid oil film bearing with piezoelectric crystal electrohydraulic active control supply orifice hole is proposed. For this kind of hybrid film bearing, the π film assumption can not hold true. In order to solve the pressure distribution, a new kind of solving method is proposed.

基于ISFD的滑动轴承转子系统不平衡振动抑制研究

由于高转速和大功率的需要,现有很多转子设备往往是基于滑动轴承设计的,因而由不平衡故障引起的振动成为影响这些设备安全运行的关键因素。为了探究整体式挤压油膜阻尼器(ISFD)对滑动轴承转子系统因不平衡故障产生振动的抑制效果,对安装有ISFD阻尼支承后的转子系统的不平衡振动响应进行了研究。首先,以实验室现有的转子试验台为基础,设计了安装有滑动轴承的ISFD阻尼支承结构,对ISFD的减振机理进行了介绍;然后,运用有限元方法,研究了ISFD弹性体的径向刚度特性;最后,搭建了单跨对称转子试验台,采用试验的方式,研究了该ISFD阻尼支承结构对转子不平衡振动的抑制效果。研究结果表明:在较宽的载荷范围内,ISFD弹性体的位移值与静载荷呈线性关系,具有优良的线性刚度特性;ISFD具有优良的阻尼特性,可以较好地抑制不同转速工况下滑动轴承转子系统的不平衡振动,在1 800 r/min的工况下,转子在x和y方向的振动降幅分别为38.4%和49.4%;ISFD阻尼支承可以有效抑制滑动轴承转子系统不平衡故障导致的工频振动,在1 600 r/min的工况下,转子在x和y方向的工频振动降幅分别为19.5%和29.4%,其减振效果良好。该研究成果可以为ISFD在滑动轴承转子系统中的实际工程应用提供借鉴,具有良好的应用前景。

基于GISFD的斜齿轮轴系减振实验研究

齿轮是机械传动装置中的重要元件,但是,齿轮传动产生的振动和噪声会危害到传动设备的正常运行,严重时甚至会造成设备损坏。为了减小和隔离斜齿轮轴系的振动,提出了一种结构新颖的G型整体式挤压油膜阻尼器(G-type Integral Squeeze Film Damper,GISFD),探究了GISFD对斜齿轮的振动特性影响。搭建基于GISFD的一级斜齿轮试验台,开展了GISFD对斜齿轮轴系的减振实验。此外,还进行了GISFD对齿面磨损斜齿轮的振动抑制实验。结果表明,GISFD对不同转速下斜齿轮轴系有较好的减振效果,在1200 r/min时,GISFD对斜齿轮主从动轴的振动降幅最高可以达到59.61%;同时,GISFD可以抑制斜齿轮啮合频率及其2倍频处的振动,振动降幅最高可以达到85.71%;GISFD对磨损斜齿轮也有较好的振动抑制效果,主动轴水平方向振动降幅在1200 r/min时可以达到83.99%。

高速柔性转子-非定心SFD系统响应特征分析与试验验证

航空发动机转子系统通常在支承处设置挤压油膜阻尼器(squeeze film damper,SFD)来实现系统减振设计,与定心SFD相比,非定心SFD结构简单紧凑,减振效果良好,但是具有更强的非线性特征,动力特性更为复杂。以某航空发动机动力涡轮转子为研究对象,建立了多支点高速柔性转子-非定心SFD系统非线性动力学模型,考虑了非定心SFD静偏心的影响,采用数值方法求解转子系统响应,结合系统不平衡响应特征、分岔图、庞家莱截面、频谱等,开展了系统非线性动力学特性研究,并通过了转子试验验证。研究结果表明,非定心SFD油膜间隙较大时,转子系统存在较强的非线性运动,频率成分丰富,减小油膜间隙能够使系统在跨临界后为单周期运动,降低系统的非线性不平衡响应;但过小的油膜间隙将导致转子系统峰值响应和对应的转速显著增大,转子可工作转速范围变小,合理的油膜间隙可以兼顾非线性振动响应和峰值转速较小,实现转子系统在大转速范围内长时间运行。

SFD作用下故障转子系统动力学特性及混沌控制

考虑挤压油膜阻尼器(squeeze film damper,简称SFD)作用,研究碰摩故障及不对中-碰摩耦合故障下系统动力学特性及SFD对系统混沌运动控制。基于Lagrange方程,建立不对中-碰摩耦合故障下SFD-转子-滚动轴承系统动力学模型,采用龙格库塔法对模型求解,并利用分岔图、Poincaré图、频谱图等进行对比分析。研究结果表明:合理油膜间隙下的SFD能有效抑制系统非协调响应以及振动幅值,使故障转子系统的混沌运动控制在稳定周期轨道上;过小的油膜间隙会形成很强的非线性油膜支反力,产生非协调频率成分,使稳定周期系统重返混沌状态;随着油膜间隙减小,SFD对不对中故障产生的典型2 X,3 X,4 X和5 X频幅值具有不同影响,其中2 X频幅值变化明显,3 X和4 X频幅值变化微弱,5 X频幅值基本不变。