考虑定子质量和碰摩面刚度的转子/定子系统碰摩响应的全局动力学特性研究

对考虑定子质量和碰撞面刚度的四自由度转子/定子模型的全局响应特性进行了研究。首先,通过解析方法确定了无碰摩响应的边界,然后,求解了同频全周碰摩解并进行了稳定性分析得到了同频全周碰摩响应的区域。在此基础上,利用非线性动力学分析的数值方法,确定了准周期局部碰摩与反向涡动失稳的边界,由此得出了参数平面内的不同碰摩响应的稳定区域图。进而研究了定子与转子质量比和碰撞面刚度对碰摩全局响应特性的影响,得到了不同碰摩响应共存及随系统参数变化的典型全局响应分岔图。     

非线性转子-机匣系统的分岔行为研究

建立了一类非线性转子-机匣系统的碰摩模型.应用数值分析的方法对其进行研究,得到了不同参数变化下系统响应随转速变化的分岔图,分析了系统参数变化对分岔过程的影响,并作出了在相应参数状态和特定转速下的Poincare截面图,揭示系统参数变化对非线性碰摩转子-机匣系统分岔特性的影响.     

系统参数对碰摩转子稳态响应的影响

本文基于线性碰摩力模型,分析了转定子存在偏心时柔性JEFFCOTT转子的碰摩响应。通过数值仿真,揭示了转子碰摩响应与系统参数之间的定性关系,指出较小的定子刚度、较大的系统阻尼有利于抑制转子的混沌振动。     

非线性碰摩力对碰摩转子分叉与混沌行为的影响

研究了具有非线性碰摩力的转子局部碰摩的分叉与混沌运动,利用计算机仿真对某发动机转子的碰摩故障进行了数值模拟,讨论了转子系统参数的变化对转子混池运动状态的影响,并与碰摩实验结果进行了比较,发现了具有非线性碰摩力的转子局部碰摩转子系统的各种多周期运动和混沌运动及其演变过程。     

基于Hertz接触理论的转子碰摩模型

对转子系统转、定子碰摩故障的过程进行了研究，建立了一个基于Hertz接触理论的转子非线性碰摩模型。通过对不同碰摩模型进行理论分析及数值仿真的对比研究表明：基于Hertz接触理论的非线性碰摩模型能更深刻地反映转、定子碰摩过程的本质特征，具有较好的实用价值。     

转子与定子碰摩的非线性动力学研究

转子与定子碰摩的动力学行为及其与系统参数关系对旋转机械设计和安全运行至关重要. 转子/定子碰摩系统是一类多参数控制的高维非光滑强非线性系统, 其动力学行为非常复杂. 本文主要从动力学与控制的角度对过去半个世纪有关转子与定子碰摩的研究成果进行归纳和总结, 其目的在于帮助读者尽可能全面系统地了解该问题的研究现状, 提炼尚待解决的问题, 以求推动转子与定子碰摩研究的进一步深入, 并为解决实际问题提供帮助. 本文将首先从碰摩局部模型和碰摩系统模型两个方面对已有的转子/定子碰摩系统的建模进行了简单的划分和归类. 其次, 以典型碰摩非线性响应为主线, 分别介绍了有关同频碰摩响应、谐波周期碰摩响应、准周期局部碰摩响应、干摩擦自激反向全周涡动响应、碰摩的全局响应行为以及碰摩响应的分岔与混沌方面的研究成果. 接下来讨论了在主被动抑制碰摩振动方面取得的结果. 最后, 给出结论并提出有待进一步研究的问题.     

一类非线性油膜轴承—转子系统的碰摩数值分析

本文结合非线性油膜力模型和碰摩速度跃迁公式,建立了描述非线性油膜轴承-转子系统碰摩的刚性约束非光滑模型。通过数值模拟,得到了该系统随转动角频率及油膜特性参数变化发生碰摩的分岔特性,并揭示出转子系统的碰摩与油膜振荡的1/2亚谐共振有密切关系。     

转子有碰摩和支承松动故障时的非线性特性研究

以具有支承松动的Jeffcott转子为研究对象，并考虑到转子系统转子和定子间的碰摩现象，分析了支承松动和碰摩对转子系统刚度的影响，建立了转子系统振动的微分方程，并用数值方法分析了其非线性动力学特性。数值分析表明，转子在碰摩和支承松动这两种非线性因素的作用下，表现出复杂的非线性行为。     

碰摩转子系统的非光滑分析

通过建立转子系统碰摩的Ｐｏｉｎｃａｒｅ映射,将对非光滑碰摩系统的研究转化为对Ｐｏｉｎｃａｒｅ映射的分析,文中主要对转子碰摩当中一类特殊的运动形式－单点碰摩下的擦边现象者了详细研究。从序列的极限理论出发分析了该映射的周期不动点的稳定性及其吸引域,得到了转子系统在接近擦边运动时解随系统参数变化的分岔情形。     

某电厂转子碰摩机理分析

我国某电厂的２００ＭＷ汽轮发电机组因严重碰摩而被迫停机。本言语建立了转子碰摩的力学模型，用数值分析的方法研究了产生碰摩机理，指出高倍频振动分量的出现是判断产生 摩的必要条件，可依之进行了转子碰摩预测和诊断。     

Determination of the global responses characteristics of a piecewise smooth dynamical system with contact

In this paper the global response characteristics of a piecewise smooth dynamical system with contact, which is specifically used to describe the rotor/stator rubbing systems, is studied analytically. A method to derive the global response characteristics of the model is proposed by studying each piece of the equations corresponding to different phases of the rotor motion, i.e., the phase without rubbing, the phase with rubbing and the phase of self-excited backward whirl. After solving the typical responses in each phase and deriving the corresponding existence boundaries in the parameter space, an overall picture of the global response characteristics of the model is obtained. As is shown, five types of the coexistences of the different rotor responses and deep insights into the interactive effect of parameters on the dynamic behavior of the model are gained.     

航空发动机整机耦合动力学模型及振动分析

面向航空发动机整机振动, 建立了航空发动机转子-滚动轴承-机匣耦合动力学模型. 该模型具有如下特点: (1)考虑转子、滚动轴承及机匣之间的耦合作用; (2)考虑了实际航空发动机的弹性支承及挤压油膜阻尼效应; (3)将转子考虑为等截面自由欧拉梁模型, 运用模态截断法进行分析; (4)考虑了滚动轴承间隙、非线性赫兹接触力以及变柔性VC(Varyingcompliance)振动; (5)考虑了转子与机匣之间的碰摩故障. 运用数值积分方法研究了航空发动机的整机振动规律, 包括: 滚动轴承VC振动分析、弹性支承刚度对耦合系统临界转速的影响、转轴模态截断阶数NM对系统响应的影响分析、挤压油膜阻尼器参数对系统响应的影响分析、突加不平衡的瞬态响应分析以及转静碰摩故障特性分析等.      

Improvement of rotor performance under rubbing conditions through active auxiliary bearings

This paper develops a new concept to enhance the adaptive capability of rotating machinery to the rubbing conditions through active auxiliary bearings. To demonstrate the feasibility of this idea, a model with a Jeffcott rotor and an active auxiliary bearing, which accounts for both the dynamics of the auxiliary bearing and the deformation on the contact surface, is investigated. The dynamics and the stability of the non-linear piecewise-smooth passive rotor/stator (auxiliary bearing) system are first studied. Then, two control approaches are proposed with the aim to reduce the rubbing severity during the rotor/stator rubbing. It is shown that by using an optimal controller, the harmful heavy rubbing between the rotor and the stator can be well stabilized to the mild light rub through the active auxiliary bearing, and the already established rotor-to-stator rubbing can even be released by using PD-controllers.     

Stability Analysis of Sliding Whirl in a Nonlinear Jeffcott Rotor with Cross-Coupling Stiffness Coefficients

An analytical study is carried out on the stability of the fullannular rub solutions of an externally excited, modified Jeffcott rotorwith a given rotor/stator clearance and cross-coupling influences. Theobtained analytical stability conditions provide an opportunity for abetter understanding of the dynamical phenomena of rotor/stator systemswith rubs, such as jump phenomena and the transition between periodicand quasi-periodic full rub responses as well as between the fullannular rubs and the partial rubs. A systematic study on the influenceof the system parameters on these phenomena is carried out. It is foundthat the simultaneous presence of the coefficient of friction and thecross-coupling stiffness coefficient with a proper value may benefit thedynamics of the rotor/stator system with rubs.     

一类分段光滑非线性平面运动系统响应特性研究

针对由一个线性子系统和一个非线性子系统构成的两自由度非自治分段光滑非线性平面运动系统的响应特性开展了研究. 该分段光滑非线性模型可用来确定对称转子/定子系统的主要碰摩响应, 且在反映非光滑系统典型特性上具有明显的特征:(1) 切换分界面是由两自由度坐标共同决定的一个幅值曲面;(2) 子系统周期解与分界面的擦碰, 不是发生在一个点上, 而是同时发生在解的所有点上;(3) 完整系统未发现由两子系统共同作用而产生的周期解. 因此, 对于该非光滑系统响应特性的研究, 很难直接利用目前有关非光滑系统平衡点和周期解分岔分析的方法. 为此, 尝试了根据子系统的响应特性, 划分出完整系统响应对分界面处切换的敏感区和非敏感区, 并针对非敏感区可由子系统解的特性求得完整系统的响应, 而针对敏感区通过子系统动力学特征的分析有助于解释完整系统响应的生成机制.     

Dynamic characteristics of a rub-impact rotor-bearing system for hydraulic generating set under unbalanced magnetic pull

Electromagnetic and mechanical forces are main reasons resulting in vibrations in hydraulic generating set. The non-symmetric air-gap between the rotor and stator creates an attraction force called unbalanced magnetic pull (UMP). The UMP can produce large oscillations which will be dangerous to the machines. In this paper, the nonlinear dynamic characteristics of a rotor-bearing system with rub-impact for hydraulic generating set under the UMP are studied. The rubbing model is established based on the classic impact theory. Through the numerical calculation, the excitation current, mass eccentricity, stiffness of shaft and radial stiffness of stator are used as control parameters to investigate their effect on the system, by means of bifurcation diagrams, Poincaré maps, trajectories and frequency spectrums. Various nonlinear phenomena including periodic, quasi-periodic and chaotic motions are observed. The results reveal that the UMP has significant influence in the response of the rotor system that the continuous increase in the excitation current induces the alternation of quasi-periodic and chaotic motions, the co-occurrence of oil whip and rub in a wide excitation range aggravates the vibration and leads to the instability of the system. In addition, the large eccentricity and radial stiffness of stator, as well as the small stiffness of shaft may lead to the occurrence of full annular rubbing while increasing the stiffness of the shaft can play an important role of suppressing the chaotic motion, reducing the vibration and improving stability of the system.     

Impact phenomena of rotor-casing dynamical systems

Rubbing and impacting between a rotor and adjacent motion-constraining structures is a serious malfunction in rotating machinery. A shaver rotor-casing system with clearance and mass imbalance is modelled with two second-order ordinary differential equations and inelastic impact conditions. The dynamics is investigated analytically, as well as by numerical simulation. A Lyapunov exponent technique is developed to characterize the topologically different behavior as the parameters are varied. The dry friction coefficient and the eccentricity of the rotor imbalance were chosen to be the two variable parameters, the effect of which on the system dynamics is illustrated through phase plots, bifurcation diagrams, as well as Poincaré maps. The results demonstrate the existence of both rubbing and impacting behavior. Depending on values of the parameters, rubbing motion in both the clockwise and counter-clockwise directions may occur. Within the impact regime, the impact behavior could be periodic, quasi-periodic or chaotic, as confirmed by the calculation of Lyapunov exponents.     

油膜支承转子系统动静件碰摩特征分析

以支承在油膜轴承上的Jeffcott转子为对象，分析了油膜力对碰摩转子动力学行为的影响。通过与刚支情形对比，发现油膜力是耦合作用于碰摩转子系统，有时能够抑制振动，有时却加剧振动。因此实际转子碰摩故障诊断过程中，必须在充分考虑支承情况的基础上建立合理的非线性动力学模型，才能为实际转子系统的碰摩故障分析提供必要的理论依据。