不平衡量对转子碰摩振动的影响

建立了与限位器碰摩的转子动力学方程 ,用数值积分方法得到了碰摩非线性动力响应。分析中考虑了陀螺效应 ,采用分段线弹性和库仑摩擦模型描述碰摩力。研究双频进动、局部碰摩、拟整圈碰摩和整圈碰摩的振动特征。讨论了不平衡量和激振力幅度变化对碰摩振动形式和特征的影响 ,并给出碰摩振动试验结果 ,以验证数值分析结论。     

转子与限位器碰摩接触时间的测量与分析

作为被动式转子振动控制元件的限位器在限制转子大幅度低频进动和过临界大不平衡响应中有良好的表现 ,为研究限位器设计和转子与其碰摩的动力行为 ,设计了转子与限位器碰摩试验台 ,进行激振碰摩实验 ,利用电容式接触传感器测量出激振碰摩过程中转子与限位器接触频度和时间 ,引入摩擦度描述碰摩的程度和频度 ,分析碰摩接触时间的统计分布特点 ,讨论了碰摩失稳运动的摩擦度特征及其影响因素。     

Self-excited vibrations of a rigid rotor rubbing with the motion-limiting stop

The solutions of the motion governing equations of the rotor-bearing-stop system are analyzed to acquire the behavior of the self-excited vibration. The numerical iteration method is put forward to obtain the periodic solution implying that the rotor whirls forward in the perfect annular orbit and keeps full rubbing with the stop.The dynamics parameters such as the stop-to-bearing stiffness ratio, the friction factor and the damping coefficient determine whether the periodic solution exists. They also affect amplitude and frequency of the periodic solution. The numerical stability analysis on the periodic solution concludes that the periodic solution behaves in an unstable motion state which will develop into the forward dry whip through full rubbing or converge to the decaying natural whirl without rubbing. The evolvement of the unstable full rubbing rests on the initial vibration energy of the rotor. The analysis on existence and stability of periodic solution may explain the observations of initiation of full rubbing observed in experiments.Suggestion on selecting dynamic parameters of the rotor-bearing-stop system is presented in order to avoid the full rubbing which has great or catastrophic harm to the rotating machinery.     

转子与限位器碰摩试验中的能量耗散

限位器或限制器是一种简单的被动式转子振动控制元件 ,它在限制转子大幅度低频进动和过临界大不平衡响应中有良好的表现。为了研究限位器的设计方法 ,考察转子与其碰摩的动力行为 ,设计了转子与限位器碰摩试验台 ,进行了激振碰摩实验 ,分析了激振碰摩过程中外力的功与转子涡动能量的关系 ,提出碰摩过程中耗散能的测试计算方法     

双转子-支承-机匣耦合系统碰摩振动响应分析及试验验证

以某型航空发动机双转子试验器为研究对象,采用Newmark-β数值积分方法求解系统的动力学响应,在考虑高低压转子中介轴承的耦合和机匣的弹性变形及其运动的基础上,建立了碰摩故障双转子-支承-机匣耦合系统动力学模型,理论分析了转速、转子偏心量和碰摩刚度对转子系统动力学特性的影响并进行了相关试验。研究结果表明：发生碰摩故障时,转子和机匣测点频谱分析图中会出现转子的倍频和组合频率,可将其作为判断系统发生局部碰摩的特征信号;随着转子偏心量和碰摩刚度的增大,碰摩幅值响应愈加明显,碰摩程度亦愈加严重;机匣测点振动量值存在衰减,后续理论建模过程中应考虑传递过程的衰减。本研究结论可为碰摩故障机理的探究和碰摩故障的诊断提供参考。     

叶尖碰摩诱发的转子系统振动响应数值分析与试验研究

针对透平机械中叶尖碰摩诱发的转子系统振动问题,基于转子-叶片-定子耦合系统模型,通过对叶尖碰摩过程的数学表征,采用谐波平衡法和Newmark-β法,分别对转定子的稳态响应和瞬态响应进行数值计算,并分析了不同参数对系统振动响应的影响。通过分析发现,叶尖碰摩下的转定子稳态响应会呈现出“硬式”非线性特征;偏移量增加会导致峰值偏移提前,非线性特征更明显;接触刚度增加使得系统的振动加剧,并且离散性增加;叶片数增加后,“削峰”现象更加明显。由于定子的约束,系统的瞬态响应峰值明显被限制了,同时,在过临界转速后,系统会出现一个不稳定运动,使得系统振动出现瞬时增加。除了仿真分析,还基于转子-叶片碰摩试验台,对叶尖单侧碰摩下的转子和定子振动位移进行了测试。从测试结果可知,转轴的振动响应也会体现叶片的振动特征,而从定子的振动响应中可以看出由于转子涡动导致的频率调制现象。     

On the contact of partial rotor rub with experimental observations

Partial rotor rub occurs when an obstacle on the stator of a rotating machinery disturbs the free whirling motion of the rotor, which is more common than full annular rub among the cases of rubbing in rotating machinery. The intermittent contacts and friction during partial rotor rub makes the phenomenon complex. The several nonlinear phenomena of superharmonics, subharmonics, and jump phenomenon are demonstrated for the partial rub using an experimental apparatus in this study. The orbit patterns are also measured experimentally. In order to explain the phenomena of partial rotor rub, the analytical model for the contact between the rotor and stator should be chosen carefully. In this respect, a piecewise-linear model and a rebound model using the coefficient of restitution are investigated on the basis of the experimental observations. Also, Numerical simulations for the two models of contact are done for the various system parameters of clearance, contact stiffness, and friction coefficient. The results show that the piecewise-linear model for partial rotor rub is more plausible to explain the experimental observations.     

转子系统碰摩故障的实验研究

建立了单盘碰摩转子系统的实验台,并且设计了一种可以模拟单点碰摩和局部碰摩的转子机构。在保证转速不变的情况下,观察碰摩转子在不同条件下的振动情况,利用波形图、频谱图、轴心轨迹图等具体分析了系统在碰摩发生前后的非线性响应和混沌特性,实验结果表明转子系统发生碰摩时,系统会激发出高倍频和分数倍频,严重碰摩时还会出现混沌现象。     

转子-滑动轴承系统不对中-碰摩耦合故障分析

针对滑动轴承支撑下的转子系统发生不对中故障进而引起不对中-碰摩耦合故障的诊断问题,基于非线性有限元法,应用短轴承油膜力、等效不对中力矩及Hertz接触理论建立双盘不对中-碰摩耦合故障转子系统动力学模型,并通过增广的拉格朗日方法来处理接触约束条件,以保证转盘和机匣相互接触时满足边界渗透深度在规定的容差范围内。同时,结合试验研究分析了在不同转速条件时,滑动轴承支撑下的耦合故障转子系统的相关动力学特性。研究表明碰摩故障在耦合故障中处于主导地位,不对中故障主要会激发高倍频谱处于从属地位;并且随着转速的提高,系统频率成分以高倍频为主,逐步由拟周期运动进入混沌运动状态,同时由于不对中力矩与碰摩力的作用,油膜失稳现象局部被抑制,一、二阶油膜振荡现象均滞后显现。研究结果可为滑动轴承支撑下耦合故障转子系统故障诊断提供依据。     

激励幅值慢变转子系统的动力学研究

建立了激励幅值慢变转子系统的动力学模型,利用渐近法对其动力学行为进行解析研究,得到了用显式形式表示的近似解析解,给出了系统响应的时域波形图和轴心轨迹图,分析了激励频率和系统阻尼对最大轴心位移的影响。结果表明:激励幅值慢变转子系统的振幅会产生相应的慢变波动,此类转子系统为多周期运动,周期数取决于激励频率和幅值慢变系数组合关系,且振动周期具有参数慢变敏感性等。     

基于实测冲击响应的转子碰摩力方向识别方法

提出了基于实测冲击响应的转子碰摩故障诊断特征提取方法.实验表明,该方法能够克服已有方法的缺点,可以准确提取信号中的冲击响应成分,且易于实际应用.在此基础上,提出了确定转子碰摩方向即静子碰摩位置的方法,该方法将转子轴心轨迹中的冲击响应成分投影到各初始相位不同的旋转坐标系中,进而以初始相位为参数,以投影能量最大化为目标进行寻优,从而确定碰摩力方向.并通过实验验证了方法的可行性.     

Coupled bending and torsional vibration of a rotor system with nonlinear friction

Unacceptable vibrations induced by the nonlinear friction in a rotor system seriously affect the health and reliability of the rotating machinery. To find out the basic excitation mechanism and characteristics of the vibrations, a coupled bending and torsional nonlinear dynamic model of rotor system with nonlinear friction is presented. The dynamic friction characteristic is described with a Stribeck curve, which generates nonlinear friction related to relative velocity. The motion equations of unbalance rotor system are established by the Lagrangian approach. Through numerical calculation, the coupled vibration characteristics of a rotor system under nonlinear friction are well investigated. The influence of main system parameters on the behaviors of the system is discussed. The bifurcation diagrams, waterfall plots, the times series, orbit trails, phase plane portraits and Poincaré maps are obtained to analyze dynamic characteristics of the rotor system and the results reveal multiform complex nonlinear dynamic responses of rotor system under rubbing. These analysis results of the present paper can effectively provide a theoretical reference for structural design of rotor systems and be used to diagnose selfexcited vibration faults in this kind of rotor systems. The present research could contribute to further understanding on the self-excited vibration and the bending and torsional coupling vibration of the rotor systems with Stribeck friction model.     

Frequency domain analysis of fluid–structure interaction in liquid-filled pipe systems by transfer matrix method

This paper is concerned with the vibration analysis of a liquid-filled pipe system, which extends the frequency domain analysis of the fluid–structure interaction from single pipe to a pipe system with multi-pipe sections using transfer matrix method. Taking into account all the three major coupling mechanisms, namely the friction coupling, Poisson coupling and junction coupling, the proposed method can be used to analyze the free vibration and the forced vibration of a pipe system with multi-pipe sections subjected to various kinds of external excitations. The transform matrix, impedance matrix and frequency equation in frequency domain are also presented and discussed. Numerical examples are presented to illustrate the application of the proposed method, which shows how the natural frequencies and mode shapes change with the radius and materials of the pipe system.     

非稳态油膜力的转子-定子-轴承系统碰摩故障研究

利用拉格朗日（Lagrange）方程建立了非稳态油膜力的转子-定子-轴承系统碰摩故障的力学模型,应用数值分析对其进行研究,得出转子系统在激励频率作为唯一控制参数时系统的轴心轨迹图和分岔图;对该系统响应的非线性行为和故障机理进行分析,从而为该类转子系统故障诊断和系统的安全运行提供理论依据.研究结果表明,当激励频率作为唯一控制参数时,系统存在周期运动、拟周期运动和混沌运动等丰富的非线性现象.     

双盘悬臂转子—轴承—机匣耦合系统碰摩故障分析

针对航空发动机转子系统的质量主要集中于压气机及涡轮部分的工程实际,将航空发动机转子系统简化为双盘悬臂连续体转子系统。建立含碰摩故障的双盘悬臂连续体转子—轴承—机匣耦合动力学模型,导出双盘悬臂连续体转子的四阶偏微分运动方程。运用变步长四阶龙格库塔法模拟系统的碰摩故障响应,分析转速与偏心量对系统碰摩故障响应的影响,发现该模型在发生碰摩故障时的一些非线性动力特性,为解决工程实际问题提供一定的理论依据。通过所建模型与单盘转子模型振动特性的比较,验证建立模型的必要性与工程意义。     

松动-碰摩发展过程中的非线性慢变问题

利用非线性动力学及转子动力学,建立了一个松动发展的模型,对松动发展的不同阶段进行振动试验,找出了转子系统发生支承松动和碰摩的特点和规律。     

Vibration analysis of a cracked rotor using Hilbert–Huang transform

In this paper, the startup transient response of a rotor with a propagating transverse crack is investigated using Hilbert–Huang Transform (HHT)—a relative novel time-frequency analysis method. The rotor with a growth crack is modeled by finite element method (FEM) and Dimarogonas’ method. The influence of crack propagating ratio (CGR) on instantaneous response of the rotor as it passes through the critical speed and sub-harmonic resonances is analyzed. The 1X (one times rotating frequency), 2X (two times rotating frequency) and 3X (three times rotating frequency) vibration components are studied when they appear, reach its peak and decay during startup process. Some conclusions are achieved which may be useful to detect transverse crack on the shaft. It demonstrates that the HHT is an effective tool for the analysis of non-linear, unsteady transient vibration response.     

基于谐波分量的转子系统碰摩故障定量诊断方法

提出一种利用碰摩转子系统响应中的高次谐波分量进行碰摩位置和碰摩力定量诊断的新方法。基于谐波平衡理论分析碰摩故障转子系统的动力学特性,证明了碰摩故障转子系统中任意两节点之间高次谐波分量之比等于无故障转子系统频率响应矩阵的相关元素之比。根据此关系,提出转子系统碰摩故障模型诊断方法和步骤:利用正常转子系统与故障转子系统响应的任意一阶谐波分量之差,结合转子系统的动力学模型,就可以诊断出碰摩的位置;进而可以根据故障转子系统响应的各次谐波分量还原出碰摩力分量。为验证该方法的有效性,对一转子系统进行偏碰和整周碰摩时的数值仿真,并分析支撑刚度及噪声对诊断方法的影响;又在模型转子试验台上进行了试验。该方法仅利用一个转速下两个节点的振动响应即可实现碰摩故障的在线定量诊断,因此便于在实际旋转机械上实行。     

质量慢变转子系统的碰摩故障小波分析

针对实际生产中某些转子系统工作时质量不断变化这一现象，建立了碰摩故障质量慢变转子系统模型。对局部碰摩的情况进行了理论分析和试验研究。利用小波时频等高图来诊断质量慢变转子系统碰摩故障，取得了比较好的效果。研究发现：无论是无故障转子系统还是碰摩故障转子系统，随着慢变质量的波动，系统响应的一倍频会产生波动，质量增大会引起响应的一倍频降低，质量减小会引起响应的一倍频升高。     

汽轮发电机组碰磨故障的典型特征研究

从定性和定量两个方面对汽轮发电机组动静碰磨故障的典型特征进行了分析和研究。在诊断汽轮发电机组动静碰磨故障时,就提取如下几类故障特征：信号频谱类特征、信号的时域波形特征、轴心运动轨迹特征、振动的时变特征、振运信号的奇异特征。本文在理论和试验研究的基础上,给出了动静碰磨故障的典型特征集合。