径向游隙对向心轴承性能的影响

1 引言滚动轴承的径向游隙对其运转性能及所在轴系的动态特性有重要的影响。径向游隙的大小直接影响球轴承的接触角和轴承内部的负荷分布,从而影响到轴承的支承刚度、轴系的振动特性、轴系上外载荷在各个轴承上的分配和轴承的疲劳寿命。本文是在对某航空发动机高速滚动轴承的拟静力学研究及其轴系振动分析中支承刚度研究的基础上,进一步研究径向游隙对滚动轴承性能的影响规律,以便于设计者在实际工作中能够找出适合轴承工况的最佳游隙,并且予以调整与控制。     

轴系轴承负荷的测量分析与调整

轴系合理校中是将轴系作为弹性连续梁进行计算分析各支承受力情况,并用调整支承位置的方法使支承力合理化.该种分析方法应用于轴系设计,从而更新了轴系设计概念和方法,使轴系运行状况大为改善.目前各船级社基本上都要求查看轴系校中轴承负荷.通过对近海多用途供应船轴系轴承负荷测量、调整进行描述和分析,以供相关专业人员借鉴与参考.     

低压轴承标高变化对600MW空冷机组轴系动特性影响研究

根据轴承负荷敏感性分析结果,研究600MW空冷机组敏感轴承对其它落地轴承及整个轴系的影响。考虑低压缸双排汽的特点,分析了3#、4#轴承在不同标高变化状态下的各轴承负荷的变化情况,研究了轴系临界转速的变化规律。结合空冷机组排汽参数的频繁变化,分析了轴颈不平衡响应特性。进而根据轴系振动特征,通过对数衰减率研究机组的稳定性问题。     

计入推力的轴系合理校中的轴承负荷比优化及轴线设计

目前没有计入推力的影响或者计入推力时推进轴系的轴承负荷法校中的计算方法没有实现艉管前后轴承的负荷比在1/2~1/3的范围内,为此提出了计入推力和不计推力的弯矩时满足艉管前后轴承的负荷比最佳的轴系合理校中设计方法。对旋转时的轴线进行优化设计,并对一个简化轴系模型进行校中计算。计算结果显示:没有考虑推力影响时艉管前后轴承的负荷比小于1/3,计入50%额定推力时,推力减轻了艉管后轴承的载荷压力,艉管前后轴承的负荷比在1/2~1/3的范围内,且全轴系的轴线是曲线,后轴承对设计基准直线轴线的偏离量较大。     

船舶推进轴系的安装校中

轴系校中质量的好坏会直接影响传动系统工况及各轴承负荷分布情况,因此良好的轴系校中对保障船舶安全运行具有重要意义。主要介绍了船舶推进轴系的主要组件及轴系安装校中,分别讲述了轴系按直线校中的轴系按轴承允许负荷校中和轴系按轴承合理负荷校中。     

基于球轴承动刚度的轴系动态特性分析与优化

轴系动态特性受轴承刚度影响,而轴承刚度随轴系转速呈强非线性。因而研究轴系动态特性首先需要确定轴承刚度。首先使用球轴承受力分析的拟静力学模型,计算球轴承不同转速下的刚度,计算轴承刚度时,考虑了轴承内圈由于离心惯性力造成的变形的影响,使刚度计算值精确化;进而使用梁单元对轴系进行离散建立轴系的有限元模型,并求解了轴系的临界转速;并以临界转速为优化目标、对轴承跨距及轴内径进行了优化,提升了轴系的动态性能。文中研究内容以Matlab为基础进行编程实现。     

基于有限元法轴段偏中时轴系校中状态的研究

依据船舶轴系直线校中原理,介绍了ANSYS环境中轴系校中建模的方法和参数的设置,并在ANSYS环境中建立了轴系校中计算的有限元模型.简述了轴系直线校中法,详细说明了轴段偏中时轴系校中的状态,得出了轴段校中时轴承负荷、轴系挠度、轴系转角、轴系剪力等参数,并与轴系偏中时轴承负荷、轴系挠度、轴系转角、轴系剪力等参数做比较,得到了轴系校中参数变化规律,同时计算得出了轴段偏中产生的附加负荷对轴系校中的影响,为船舶轴系校中设计及检修提供了依据.     

船舶轴系校中方法及影响因素分析

从按直线性校中原理校中、按轴系上允许负荷用测力计校中、按轴承上合理负荷校中几方面介绍了船舶轴系校中的方法,并分析了影响轴系校中质量的诸因素。     

大型汽轮发电机组轴系稳定性研究

本文建立了大型汽轮发电机组轴系稳定性的基本方程,轴承类型可以全部是固定瓦或可倾瓦轴承,也可以是固定瓦和可倾瓦轴承的组合。对某国产300W汽轮发电机组的稳定性进行了数值计算,提出了轴系集中质量合理划分的原则。用本文提出的方法和J. W. Lund法研究了一台以可倾瓦轴承为支承的离心压缩机组的稳定性,结果表明后者与实际情况相差较大。     

由轴颈扬度计算汽轮发电机组轴承载荷分布方法

在传递矩阵基础上,提出一种由轴颈扬度分布递推计算汽轮发电机组轴系各轴承载荷分配方法。在轴承处将轴拆分为若干段,任意一个轴段内两端轴颈扬度差值取决于轴段内弯矩、剪力、轴段参数和轴承载荷。第1个轴承左端截面弯矩和剪力可以由力和力矩平衡方程直接求出。由该值和前2个轴承轴颈扬度值可以求出第1个轴承载荷,进而求出第2个轴承左端截面弯矩和剪力。将该方法递推应用到其后更多轴段,即可逐步求出各轴承载荷。在转子试验台上就轴系两种对中状况下的轴承载荷分配进行测试,并与顶举法测试结果进行比较,验证本方法的可行性。将该方法应用于某台大型汽轮发电机组轴承载荷分布识别。该方法是一种整体识别法,可以应用于联轴器螺栓不解体情况下轴系对中状况分析。     

The rotordynamic analysis of the vibration considering the hydro-electric force supported by rolling elements in 500 kW Francis turbine

A Francis turbine which is one of the reaction water turbine types is mainly used in the multipurpose dam. The purpose of this research is to explain the vibration characteristics due to the various causes generated in Francis-turbines generator system. The hydrodynamic force was determined to use the fluid dynamics analysis considering the exciting force that is transmitted to the shaft from the runner part. Besides, in the generator parts electromagnetic forces can have a severe influence on the rotor dynamics in some situations. Because, the hydro turbine-generator system supported by various types of bearing, mechanical vibration analysis is also necessary. Based on a real small-scale Francis-turbine generators parameter, several analysis were performed the stability at the operating speed of the rotor such as natural frequency analysis and forced response analysis. Through this analysis, aside from the mechanical factor, electromagnetic and hydrodynamic factors have also been found to affect vibration.     

Nonlinear Dynamic Characteristic Analysis of the Shaft System in Water Turbine Generator Set

A 3D finite element vibration model of water turbine generator set is constructed considering the coupling with hydropower house foundation. The method of determining guide bearing dynamic characteristic coefficients according to the swing of the shaft is proposed, which can be used for studying the self-vibration characteristic and stability of the water turbine generator set. The method fully considers the complex supporting boundary and loading conditions; especially the nonlinear variation of guide bearing dynamic characteristic coefficients and the coupling effect of the whole power-house foundation. The swing and critical rotating speed of an actual generator set shaft system are calculated. The simulated results of the generator set indicate that the coupling vibration model and calculation method presented in this paper are suitable for stability analysis of the water turbine generator set.     

风电偏航轴承轮齿的力学性能研究

风电偏航轴承作为风力发电机组连接塔筒和机舱关键部件,在实际运行中多采用四个小齿轮驱动。研究了偏航轴承轮齿在运行中的力学性能,以外齿式偏航轴承为例,考虑了轴承受均载与非均载的情况,利用有限元分析软件ABAQUS分别进行了模拟,比较了各种情况下偏航轴承轮齿的受力结果,得出结论为轮齿最大弯曲应力发生在主动小齿轮的齿根处,在非均载状态下偏航轴承轮齿最大齿根弯曲应力和齿面接触应力要比均载情况下大30%左右,并且提出了非均载系数,为设计校核偏航轴承提供了参考。     

发电机转子负序涡流场分析与计算

汽轮发电机的不平衡负载将使转子感应出两倍工频(100 Hz)的涡流,引起转子铁芯及其阻尼电路的发热,从而限制了发电机的负序能力。利用复数表面阻抗的概念给出了转子负序涡流场的分析方法。在此基础上,以转子极面加阻尼系统的300 MW汽轮发电机为例,计算了发电机稳态负序运行时转子上的涡流分布和损耗分布。根据计算结果,讨论了转子极面加阻尼系统对提高发电机负序能力所起的作用。     

Evaluation of impact dynamics and contact forces in a hydropower rotor due to variations in damping and lateral fluid forces

Damages due to contact between the runner and the discharge ring have been observed in several hydroelectric power units. The damage can cause high repair costs of the runner and the discharge ring as well as considerable production losses.In this paper a rotor model of a 45 MW hydropower unit is used for the analysis of the rotor dynamical phenomena occurring due to contact between the runner and the discharge ring for different grades of lateral force on the turbine and bearing damping. The rotor model consists of a generator rotor and a turbine, which is connected to an elastic shaft supported by three isotropic bearings. The discrete representation of rotor model consists of 32 degrees of freedom; to increase the speed of the analysis, the size of the model was reduced with the IRS method to a system with 8 degrees of freedom.Results are presented in bifurcation diagrams, maximum contact force, Poincaré map and phase portrait. Simulations indicate that the contact forces between the turbine and the discharge ring are large, with considerable risks for serious damage as a consequence. The analysis shows that the risk for contact and damage are large for relatively small lateral turbine loads when the gap between the turbine and the discharge ring is small and the contact stiffness is high.     

A novel nonlinear model of rotor/bearing/seal system and numerical analysis

A novel nonlinear model of rotor/bearing/seal system based on the Hamilton principle is proposed for steam turbine systems in power plants. The Musznyska model and unsteady bearing oil-film force model were applied to describe the nonlinear steam excitation force and oil-film force. The Runge-Kutta method was used to solve the motion equation of the rotor/seal/bearing system. The dynamic characteristics of the rotor/bearing/seal system were analyzed with bifurcation diagrams, time-history diagrams, trajectory diagrams, Poincare maps and frequency spectrums. The numerical analysis indicates that the seal force and the oil-film force influence the nonlinear dynamic characteristics of the rotor system. With the increase of rotation speed, the rotor system exhibits rich forms of periodic, double-periodic, multi-periodic, quasi-periodic and chaotic motion. The combined impact of steam excitation force and bearing oil-film force may cause a severe vibration which seriously affects the safety and stability of the rotor. The presented model provides a theoretic foundation for further research on the ultra-supercritical steam turbines.     

随机风速下风力发电机组载荷传递特性研究

选取指数律函数描述平均风速,运用基于自回归模型的线性滤波法建立的风速模型模拟自然界随机风速。根据动量矩定理和简单的弹簧-质量-阻尼模型建立风力发电机组传动系统刚性传动模型及柔性传动模型来描述系统动态特性。以5MW变速变桨距风力发电机组参数为依据,计算随机风速下两种不同传动模型对风轮叶片以及发电机转子的动态响应的影响,并对结果进行对比分析。基于柔性传动模型,研究不同主轴刚度对传动系统动态响应的影响,得出最佳主轴刚度,并利用雨流计数法描述不同主轴刚度下风力发电机组传动系统的动态响应。研究结果可为风力发电机组传动系统动态特性的研究提供载荷数据。     

大型汽轮发电机组轴承负荷在线监测方法研究

提出大型汽轮发电机组轴承负荷在线监测的意义；对比分析目前大型汽轮发电机组轴承负荷的各种测试方法；指出现11轴承支承力法，即通过安装在轴承与轴承座间的测力传感器直接测量轴承负荷的方法，是对大型汽轮发电机组轴承负荷在线监测的一种较好方法；并提出测轴承支承力法的关键技术，即机组轴承负荷传感器的结构适应性、功能适应性、长期稳定性和可靠性要求；研究测轴承支承力法对大型汽轮发电机组轴承负荷在线监测的可行性。研究结果表明，测轴承支承办法是必要和可行的。     

Load and dynamic characteristic analysis of wind turbine flexible blades

Aiming at the Megawatt (MW) scale wind turbine, a dynamic analysis and simulation method is presented to research blade loads and dynamic characteristics. To consider blade flexible deformation, the whole blade was divided into a number of units. Each unit was treated as a rigid body, the flexible connection between two adjacent units is considered. A nacelle coordinate system, a rotating shaft coordinate system, and a blade coordinate system were employed to describe the wind turbine blade. In those coordinate systems, blade inertial load calculation model, centrifugal force load calculation model and gravity load calculation model are established. Combining load model with the whole model of wind turbines, the real-time dynamic simulation model of blade loads was established in Simulink circumstance and a numerical simulation was performed. Based on the simulation analysis, some research results were obtained. When the large instantaneous fluctuation of electromagnetic torque of generator happens, rotor speed does not appear to have large fluctuation due to the inertia of the wind rotor, but the blade vibration speed changes obviously. Gravity has a periodic variation in the process of blade rotation and has a large influence on the edgewise moment. The research results provide a helpful reference for the structure design, operation, and control of wind turbines.