转子系统瞬时撞击刚度的定量计算方法

通过对转子与定子碰撞过程的线性化处理，得到了转子系统瞬时碰撞刚度的定量计算公式。由该公式确定的碰撞刚度不但与转子和定子的杨氏模量有关，而么与转子的径向速度有关。因此该公式较准确地确定了转子系统的碰撞过程。本文通过实例对如何运用此公式确定转子系统的碰撞刚度进行了详细的论述。     

磁悬浮挠性转子系统模型复合辨识方法

针对磁悬浮挠性转子的纯有限元分析模型精度低的问题,提出一种磁悬浮挠性转子系统模型复合辨识方法。该方法首先采用有限元方法把磁悬浮挠性转子划分为多个Timoshenko梁单元,建立磁悬浮挠性转子系统模型,并对其挠性临界频率、阻尼、刚度和振型等关键参数进行分析,进而得到磁悬浮挠性转子的等效降阶数学模型;然后采用鲁棒自适应方法分析磁悬浮挠性转子系统的动态特性;最后,采用变LEVY方法从动态特性分析数据中对磁悬浮挠性转子进行系统辨识,校正有限元分析得到的降阶数学模型。实验结果表明,本方法可以得到磁悬浮挠性转子较为准确的系统模型。     

螺桨转子颤振涡动的一种算法

介绍螺桨转子系统颤振涡动的一种算法。本算法考察桨叶的振动变形，桨轴－支承系统的振动特性，以及螺转子的不平衡力。利用本算法对一模型螺桨转子和一实际螺桨转子进行了分析计算，对螺桨转子轴头动刚度、浆叶弹性变形、桨盘不平衡度等因素对螺桨转子系统颤振涡动的影响进行了分析，表明螺桨转子轴头动刚度下降时，螺浆发生颤振涡动的极限飞行速度下降。模型螺桨转子的计算结果与风洞试验结果相当吻合，证明本算法是正确的。     

转子系统非线性动力学DEM建模研究

将DEM方法引入转子系统非线性动力学的分析计算,对其建模过程和有关本构关系,作了比较详尽的介绍。该模型可用于碰摩、弯曲振动和扭转振动等转子系统的大部分动力学和运动学问题分析计算,不仅适用于单跨转子系统,也适用于多跨转子系统,尤其是在碰摩计算时,可考虑其摩擦特性随时间历程而变的特点,从而使分析计算更加接近实际情况。     

迷宫密封转子系统非线性动力稳定性的研究

研究迷宫密封对转子系统动力稳定性的影响，迷宫密封的气动力采用Muszynska非线性力模型，计算了单盘Jeffcott转子非线性动力学特性。对Jacobi矩阵的分析表明，在密封力的影响下，转子达到一定转速后开始失稳，发生Hopf分岔，进入周期涡动状态，涡动幅度随转速的提高而增大，提高到一定程度，密封和转子发生碰摩，采用Runge-Kutta法数值模拟了转子的轴心轨迹。最后分析了迷宫密封的物理和结构参数对系统运动特性的影响。     

准三维旋转流体模型及其在部分充液转子稳定性分析中的应用

提了了一种简单的无粘旋转流体准三维模型,并给出了旋转流体对转子作用力的详细表达式,然后用该模型分析了部分充液刚性悬臂转子系统的稳定性,并与实验结果进行了比较,两者在定性上符合较好,准三维无粘流体模型与其它的无粘膜型一样也仅能用来分析无外阻尼或外阻尼较小的部分充液转子系统的稳定性问题。     

Effects of a crack on the stability of a non-linear rotor system

The stability of a rotor system presenting a transverse breathing crack is studied by considering the effects of crack depth, crack location and the shaft's rotational speed. The harmonic balance method, in combination with a path-following continuation procedure, is used to calculate the periodic response of a non-linear model of a cracked rotor system. The stability of the rotor's periodic movements is studied in the frequency domain by introducing the effects of a perturbation on the periodic solution for the cracked rotor system.It is shown that the areas of instability increase considerably when the crack deepens, and that the crack's position and depth are the main factors affecting not only the non-linear behaviour of the rotor system but also the different zones of dynamic instability in the periodic solution for the cracked rotor. The effects of some other system parameters (including the disk position and the stiffness of the supports) on the dynamic stability of the non-linear periodic response of the cracked rotor system are also investigated.     

Nonlinear dynamics of a cracked rotor in a maneuvering aircraft

The nonlinear dynamics of a cracked rotor system in an aircraft maneuvering with constant velocity or acceleration was investigated, The influence of the aircraft climbing angle on the cracked rotor system response is of particular interest and the results show that the climbing angle can markedly affect the parameter range for bifurcation, for quasiperiodic response and for chaotic response as well as for system stability. Aircraft acceleration is also shown to significantly affect the nonlinear behavior of the cracked rotor system, illustrating the possibility for on-line rotor crack fault diagnosis.     

Dynamic stiffness characteristics of aero-engine elastic support structure and its effects on rotor systems: mechanism and numerical and experimental studies

The support structure of a rotor system is subject to vibration excitation,which results in the stiffness of the support structure varying with the excitation frequency(i.e., the dynamic stiffness). However, the dynamic stiffness and its effect mechanism have been rarely incorporated in open studies of the rotor system. Therefore, this study theoretically reveals the effect mechanism of dynamic stiffness on the rotor system. Then,the numerical study and experimental verification are conducted on...     

Experimental and numerical analysis of nonlinear dynamics of rotor–bearing–seal system

Nonlinear dynamics and stability of the rotor–bearing–seal system are investigated both theoretically and experimentally. An experimental rotor–bearing–seal device is designed and corresponding tests are carried out. The experimental rotor system is simplified as the Jeffcott rotor. The nonlinear oil–film forces are obtained under the short bearing theory and Muszynska nonlinear seal force model is used. Numerical method is utilized to solve the nonlinear governing equations. Bifurcation diagrams, waterfall plots, Poincaré maps, spectrum plots and rotor orbits are drawn to analyze various nonlinear phenomena and system unstable processes. Theoretical results from numerical analysis are in good agreement with results from experiments. Conclusions are drawn and prove that this study will contribute to the further understanding of nonlinear dynamics and stability of the rotor system with the fluid-induced forces from oil–film bearings and the seals.     

Subharmonic resonance of a symmetric ball bearing–rotor system

The performance of a ball bearing–rotor system is often limited by the occurrence of subharmonic resonance with considerable vibration and noise. In order to comprehend the inherent mechanism and the feature of the subharmonic resonance, a symmetrical rotor system supported by ball bearings is studied with numerical analysis and experiment in this paper. A 6DOF rotordynamic model which includes the non-linearity of ball bearings, Hertzian contact forces and bearing internal clearance, and the bending vibration of rotor is presented and an experimental rig is offered for the research of the subharmonic resonance of the ball bearing–rotor system. The dynamic response is investigated with the aid of orbit and amplitude spectrum, and the non-linear system stability is analyzed using the Floquet theory. All of the predicted results coincide well with the experimental data to validate the proposed model. Numerical and experimental results show that the resonance frequency is provoked when the speed is in the vicinity of twice synchroresonance frequency, while the rotor system loses stability through a period-doubling bifurcation and a period-2 motion i.e. subharmonic resonance occurs. It is found that the occurrence of subharmonic resonance is due to the together influence of the non-linear factors, Hertzian contact forces and internal clearance of ball bearings. The effect of unbalance load on subharmonic resonance of the rotor system is minor, which is different from that of the sliding bearing–rotor system. However, the moment of couple has an impact influence on the subharmonic resonances of the ball bearing–rotor system. The numerical and experimental results indicate that the subharmonic resonance caused by ball bearings is a noticeable issue in the optimum design and failure diagnosis of a high-speed rotary machinery.     

具有封严蓖齿转子系统的动力稳定性分析

封严蓖齿的气弹力对转子系统的稳定性起重要作用，本文建立了具有封严蓖齿的转子系统动力稳定性的分析方法，该方法利用传递矩阵法建立系统的主导方程，将封严蓖齿的气弹力以等效刚度及等效阻尼系数的方式引入转子系统的主导方程，用数值积分法解主导方程，求得系统的动力特性，根据扰动解判断系统的稳定性。本文所建立的分析软件，也可计算转子系统的不平衡响应、临界转速、突加不平衡响应等。文中对一模型转子进行了算例分析。     

转子系统随机支撑刚度参数的识别

基于Riccati摄动随机传递矩阵方法建立的转子系统特征值与随机参数变量间的函数关系,给出了转子系统随机参数的识别方法和详细步骤,可用于识别随机参数的均值和方差。以改装的Bently实验转子为研究对象,通过大量测试,识别出了转子系统的随机支撑刚度参数,建立了该转子系统的随机参数动力学模型。该模型可用于研究转子系统的随机参数动力学问题。     

异步进动转子与限位器碰摩试验

利用限位器来限制储能飞轮实验转子的大幅度低频异步进动,设计了转子与限位器碰摩试验装置,研究转子的碰摩振动。分析了转子内表面碰摩力对转子运动的影响。转子与内置式限位器发生稳定的局部碰摩时,转子低频进动幅值不再增加,转子自转速度保持不变。碰摩转子的强迫振动在时域及频域都表现出了复杂性,碰摩冲击作为宽频激励,能够激励出转子-支承系统的第二模态正向进动。     

应用谐波小波提取转子系统动力参数

临界转这是离心压缩机转子系统的主要动力参数之一,尤其高阶临界转速在试车中不易被识别。本文应用谐波小波对转子系统试车振动信号进行分析,对转子高阶临界转速进行了分辨识别,结果令人满意。     

Stability and bifurcation of unbalance rotor/labyrinth seal system

The influence of labyrinth seal on the stability of unbalanced rotor system was presented . Under the periodic excitation of rotor unbalance , the whirling vibration of rotor is synchronous if the rotation speed is below stability threshold, whereas the vibration becomes severe and asynchronous which is defined as unstable if the rotation speed exceeds threshold . The. Muszynska model of seal force and shooting method were used to investigate synchronous solution of the dynamic equation of rotor system. Then , based on Floquet theory the stability of synchronous solution and unstable dynamic characteristic of system were analyzed.     

涡轮泵转子-迷宫密封系统的非线性稳定性和分岔

研究迷宫密封对某一工程涡轮泵转子系统动力特性的影响,迷宫密封力采用Muszynska非线性力模型,应用有限元法建立转子系统的动力学方程,采取系统动力学方程中包含的高阶线性自由度和低阶的非线性自由度进行分块处理的方法,有效地缩短了求解时间。根据Floquet理论,判别系统的临界失稳转速,并由Floquet乘子来确定系统失稳后分岔方式。采用分块-Newmark法数值模拟了转子二涡轮盘的轴心轨迹。最后分析了涡轮泵转子二涡轮盘的质量偏心同相位和存在90度相位差时对转子系统运动特性的影响。     

转子系统振动变参控制中的瞬态响应

本文以可变参数的挤压油膜阻尼器作为控制元件，研究了转子在稳态转速及加速运动过程中进行变参控制时的瞬态响应问题。结果说明了对转子系统的振动进行分段变参控制，无论是在稳态还是在加速运动过程中，一般都可以取得满意的控制效果，不仅可以减小转子系统的振动，而且还可以使转子系统平稳地通过具有较大振动的共振区，但变参位置不应在多值转速区内。     

非线性转子的低频振动失稳机理分析

包括两部分内容：１）材料内阻作用下转子自激振动的局部分岔分析；２）考虑湍流因素的滑动轴承油膜力作用下转子轴承系统油膜失稳机理的全面分析。结果表明，非线性转子的自激振动表现出复杂的动力学现象，这些低频振动现象的揭示，为工程上转子故障的识别和预防提供了理论依据。     

Effects of axial preload of ball bearing on the nonlinear dynamic characteristics of a rotor-bearing system

This research studies the effects of axial preload on nonlinear dynamic characteristics of a flexible rotor supported by angular contact ball bearings. A dynamic model of ball bearings is improved for modeling a five-degree-of-freedom rotor bearing system. The predicted results are in good agreement with prior experimental data, thus validating the proposed model. With or without considering unbalanced forces, the Floquet theory is employed to investigate the bifurcation and stability of system periodic solution. With the aid of Poincarè maps and frequency response, the unstable motion of system is analyzed in detail. Results show that the effects of axial preload applied to ball bearings on system dynamic characteristics are significant. The unstable periodic solution of a balanced rotor bearing system can be avoided when the applied axial preload is sufficient. The bifurcation margins of an unbalanced rotor bearing system enhance markedly as the axial preload increases and relates to system resonance speed.