基于复数相移陷波的磁悬浮转子系统自平衡控制

为抑制磁悬浮转子系统的不平衡振动力,提出了一种基于复数相移陷波器和前馈控制的自平衡控制算法。介绍了磁悬浮转子系统的结构和工作原理,给出了含转子不平衡的磁悬浮转子系统动力学模型,分析了不平衡振动力的电气特性。推导了不平衡振动力的抑制条件,指出功率放大器引起的幅值和相位误差是影响不平衡振动抑制效果的主要因素。将磁悬浮转子两自由度平动方程转换为单自由度复数方程,设计了复数相移陷波器,建立数学方程并讨论了中心频率的幅值和相位特性。最后以磁悬浮控制力矩陀螺为测试平台,对提出的控制算法进行了实验验证。结果表明:采用该算法后不平衡振动力减小了94.1%,验证了该算法的有效性。此外本算法还具有动态过程平滑、计算量少等优点。     

组合转子疲劳-蠕变联合损伤机理研究

以某重型燃气轮机组合转子为研究对象,建立了组合转子整体损伤模型;将纯疲劳和纯蠕变的损伤研究作为基础,根据损伤力学累积模型将联合作用下的损伤变量表示为两种损伤的非线性叠加,揭示了疲劳-蠕变联合作用下组合转子的损伤机理;对疲劳-蠕变联合条件下组合转子的损伤规律进行了实验验证。结果表明,建立的整体损伤模型是正确的、有效的,可为部件损伤预测组合转子的整体损伤提供参考。     

基于DSP和LabVIEW的电动机转子断条故障诊断

为了实现对鼠笼式异步电动机转子断条故障的实时诊断,设计了一套以TMS320F2812和LabVIEW为核心的转子断条故障诊断装置。该装置以TMS320F2812为主控芯片,实现对异步电动机定子侧电流信号的采集,通过DSP的串口模块将采集到的信号传送到由LabVIEW构建的上位机信号处理平台。针对定子侧电流信号中工频分量对断条故障特征分量的干扰较大,严重地影响断条分量的识别,LabVIEW处理平台采用自适应陷波器算法对工频信号进行陷波处理,在FFT频谱上实现对断条故障特征分量的识别。实验证明,该装置能够实现对断条故障进行实时监测,并能够在FFT频谱上对断条故障特征分量进行识别。     

发电机转子电弧放电损伤检验及过热组织研究

某电厂发电机组发生电网反送电事故后,转子本体与转子表面接触的各部件间因产生电弧放电现象,造成转子本体损伤。为对受损转子进行可用性评价,需对事故转子的损伤情况进行准确分析。本文对为正确分析转子受损情况而需进行的无损检验内容以及电孤放电造成的转子本体过热组织的特性和范围进行了研究,并对相关检验结果进行了分析。结果表明,转子本体损伤部位经处理后无宏观和微观裂纹,转子本体过热组织为针状马氏体,最大深度为2．8mm。     

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.     

Accumulated damage process of thermal sprayed coating under rolling contact by acoustic emission technique

The accumulated damage process of rolling contact fatigue (RCF) of plasma-sprayed coatings was investigated. The influences of surface roughness, loading condition, and stress cycle frequency on the accumulated damage status of the coatings were discussed. A ball-ondisc machine was employed to conduct RCF experiments. Acoustic emission (AE) technique was introduced to monitor the RCF process of the coatings. AE signal characteristics were investigated to reveal the accumulated damage process. Result showed that the polished coating would resist the asperity contact and remit accumulated damage. The RCF lifetime would then extend. Heavy load would aggravate the accumulated damage status and induce surface fracture. Wear became the main failure mode that reduced the RCF lifetime. Frequent stress cycle would aggravate the accumulated damage status and induce interface fracture. Fatigue then became the main failure mode that also reduced the RCF lifetime.     

含转子不平衡的磁轴承建模与同频电流抑制

为实现含转子不平衡的磁轴承系统动力学建模与同频电流抑制,分析了同频电流、力和力矩的产生机理,即转子不平衡（含静不平衡和动不平衡）经控制器、功放系统、感应电动势在磁轴承线圈中引起同频电流,进而与电流刚度和位移刚度相互作用产生力和力矩,完成了径向4自由度全主动磁轴承系统的建模。对该模型进行了数学求解和验证,提出了一种基于相移通用陷波反馈控制的同频电流抑制方法,可有效抑制控制器、功放系统和感应电动势产生的同频电流。仿真和实验验证了该方法的有效性,与传统的控制器串联陷波器方法相比,基于相移通用陷波反馈控制的同频电流抑制方法还可减少感应电动势引起的同频电流,同频电流进一步衰减了8.8dB。     

高速喷漆涡轮转子轴疲劳寿命分析

通过对高速喷漆涡轮转子轴质量等效,将涡轮系统复杂振动转化为简单的单自由度振动问题。在此基础上,论述了等幅应力下有限疲劳寿命分析方法,推算出高速喷漆涡轮转子轴有限疲劳寿命,分析了该转子轴直径、悬臂长、振动幅值及偏心距对疲劳寿命的影响规律。为转子轴的维修和制造奠定基础。     

含离散源损伤Z向增强复合材料加筋板压缩特性研究

以含穿透中央筋条的切口模拟离散源损伤,对无增强、Z-pin增强、改进锁式缝合增强、Tufting缝合增强复合材料加筋板进行轴向压缩试验,研究含离散源损伤Z向增强加筋板的损伤扩展模式与破坏特征。结果表明,壁板和筋条间的Z向增强有效控制了壁板与筋条的脱粘,提高了加筋板的屈曲载荷。切口前端的分层只引起局部的屈曲,沿切口方向未切断筋条的断裂和壁板边缘的突然压溃导致加筋板的最终破坏。三维有限元渐进损伤分析结果显示,选用Hashin判据作为失效判据,可以很好地模拟含离散源损伤复合材料加筋板的轴向压缩渐进损伤过程。采用线约束模拟壁板与筋条翼缘之间的Z向增强是合理的,线约束的引入在损伤扩展至筋条下方壁板区域后有效控制了损伤的扩展。     

基于双频Bode图的磁悬浮控制力矩陀螺转子弹性自激振动抑制用陷波器设计

由于强陀螺效应和控制系统的高频滞后,磁悬浮控制力矩陀螺转子存在高频弹性自激振动,需要采用陷波器（Notch Filter－NF）进行相位校正和抑制,但是目前仍然缺乏有效的NF参数设计方法。本文提出一种基于双频Bode图的NF参数设计方法,采用双频Bode图分析转子弹性模态稳定性,得出不同转子转速下对NF相位校正角的要求,然后在保证转子章动稳定性的前提下优化设计NF参数。采用该方法设计的NF有效抑制了转子的弹性自激振动,使所研制的磁悬浮控制力矩陀螺稳定升速到20000r/min,验证了该方法的实用性和有效性。     

多轴变幅载荷下基于载荷支配模式的缺口件疲劳寿命预测方法

提出一种多轴变幅载荷下基于载荷支配模式的缺口件疲劳寿命预测方法。首先,通过循环计数方法确定多轴变幅载荷历程的计数循环(反复);其次,通过材料的循环应力应变关系和Neuber法推导出虚拟等效应变与真实等效应力之间的关系,并且分别将拉伸型和剪切型Shang-Wang多轴疲劳损伤参数替换虚拟等效应变幅来求解临界面上的真实等效应力幅;然后,通过真实等效应力幅和Neuber法则计算临界面上真实的拉压和剪切等效应变幅,并运用Manson-Coffin方程分别计算缺口部件的拉压和剪切疲劳寿命;最后,选择拉压和剪切疲劳损伤值中的较大值作为每个计数反复的疲劳损伤,并采用Miner法则进行疲劳损伤累积。缺口件多轴疲劳试验结果表明,采用基于载荷支配模式的缺口件疲劳寿命预测方法具有较高的预测准确度。     

材料重复冲击损伤模型与数值计算方法研究

基于连续介质损伤力学,将有效应力概念和应变等效假设应用于Johnson-Cook本构模型中,建立了重复冲击载荷作用下材料力学性能退化的损伤模型,以及考虑材料性能退化对冲击应力应变响应影响的数值计算方法。首先,推导了基于损伤耦合J-C本构模型的应力应变数值计算关系式,并在ABAQUS中进行二次开发,采用两种方法实现了考虑损伤影响的应力应变数值计算。进一步,建立了试件在重复冲击下损伤累积的计算方法,并采用所建方法对含缺口三点弯试件的重复冲击损伤进行了数值计算,研究了缺口根部应力应变及损伤度,并对试件整体损伤规律进行了分析。进一步开展了缺口三点弯试件的重复冲击试验,通过计算结果与试验结果的对比验证了建立的数值计算方法的可行性和适用性。与无损伤耦合模型计算结果相比,损伤耦合模型更能合理反映出缺口根部材料的力学性能退化过程以及损伤累积与冲击响应之间的相互影响。     

深沟球轴承装球口结构与工艺改进

在加工带装球口的单列深沟球轴承时,装球口的加工工艺为热处理前铣削加工,热处理后磨削加工。由于没有专用的磨削机床,无法进行自动磨削,操作者只能手持套圈在砂轮上进行磨削,使装球口锁量尺寸精度无法保证,散差较大,而且劳动强度大,安全性低。通过对加工工艺进行改进,解决了存在的问题;同时,改变了装球口角度,减少了钢球的挤压损伤,提高了轴承质量。     

轴承-转子系统自激振动及迟滞、跳跃现象

采用长轴承解析模型研究滑动轴承支承的平衡单盘柔性转子-轴承系统的自激振动，把结合打靶法的延续算法应用于柔性平衡转子-轴承系统Hopf分叉后周期解的追踪和求解上，基于Floquet理论对极限环的稳定性加以分析，研究了不同系统参数下产生极限环的Hopf分叉的不同过程及特性，分别对超临界及亚临界Hopf分叉进行了描述和分析，结果表明亚临界Hopf分叉会引起突跳、迟滞现象，并可引发转子系统难以预测的振动故障，在设计中应避免这种参数条件。     

主被动磁悬浮转子的不平衡振动自适应控制

针对主被动磁悬浮控制力矩陀螺转子高速旋转时产生的不平衡振动,提出了基于滑模观测器和陷波器的主被动磁悬浮转子不平衡振动自适应控制方法。该方法采用滑模观测器使同频振动的控制不受磁轴承的刚度参数摄动和磁力耦合的影响,将滑模观测器与陷波器结合,无需区分电流刚度力和位移刚度力,无需设计算法补偿功率放大器的影响,可自适应消除不平衡振动。对该方法进行了仿真和实验验证。仿真结果显示该方法可使同频轴承力大幅减小;实验结果显示,虽然主被动磁悬浮转子的被动轴承不可控,同频振动仍由0.053g减小为0.012g,减小了77%。得到的结果表明,该方法不仅适用于主被动磁悬浮转子,也适用于全主动磁悬浮转子。     

基于有限元的呼吸裂纹转子动力学特性

采用有限单元法建立了含裂纹Jeffcott转子的有限元模型,利用应变能释放率方法得到了裂纹单元的刚度矩阵,采用应力强度因子为零法模拟了裂纹的呼吸效应.计算分析了在一个稳态旋转周期内裂纹开闭的规律,以及直斜裂纹转子振动响应的特点.计算结果表明,斜裂纹开始张开以及闭合的时间迟后于直裂纹,斜裂纹处于全闭与全开状态所经历的时间比直裂纹长.直斜裂纹转轴的1X和2X倍频响应随着裂纹深度的增加而增加,但3X倍频分量变化不大.     

大型发电机转子开裂原因初步分析

从转子的原材料和热处理工艺方面分析了大型发电机转子在运行中开裂的原因.结果表明:由于转子的热处理工艺不合理导致转子材料脆性和缺口敏感性较大,在应力集中时,发生了开裂事故.     

Limit cycle of the self-excited oscillations of the rotor blades of a centrifugal compressor

The limit cycle of the self-excited oscillations of the rotor blades of a centrifugal compressor caused by pure bending flutter is studied with the help of experimental tensiometric data. This makes it possible to determine the nonlinear terms that elaborate the linear concentrated model used to describe the pure bending flutter of rotor blades.     

基于磨料水射流的螺杆转子加工新方法研究

螺杆转子传统加工过程中存在刀具磨损和过高切削热量等难题。为此,将具有无刀具磨损、切削热量低、绿色环保特点的磨料水射流加工方法引入螺杆转子加工研究之中,提出了磨料水射流多轴联动加工螺杆转子的新方法,以提高转子加工精度和效率。采用任意拉格朗日与欧拉方法构建了转子加工模拟模型,将模拟分析结果与实验数据进行比较,验证了模拟模型的正确性。最后,通过磨料对水射流多轴联动加工模拟结果的分析,证明了螺杆转子加工新方法的合理性。     

Effect of cooling flow on thermal performance of a gas foil bearing floating on a hot rotor

This paper presents the measurements of the thermal behavior of a gas foil bearing (GFB) floating on a hot rotor in a tangential air injection cooling scheme. The cooling air was tangentially injected against rotor spinning into the inlet mixing zone of the test GFB. The hollow rotor was heated by a cartridge heater. The GFB temperatures were measured at intervals of 30 deg along the circumference of the axial center except for at 45 deg, where the cooling flow is injected. The rotor temperatures were measured near the GFB side ends using an infrared thermometer, which was calibrated with a thermocouple. Load cells measure the static load and bearing torque. The baseline rotor temperature was measured without GFB over the axial length at rotor speeds up to 15 krpm and for increasing heater temperatures up to 400 °C. The results showed relatively uniform rotor temperatures at the test journal GFB section, and severe heat convections on the rotor surfaces. The GFB and rotor temperatures were measured under a static load of 80 N for increasing heater temperatures of 100 °C, 200 °C, 300 °C and 400 °C and with increasing cooling flow rates of 100 liter/min, 150 liter/min, and 200 liter/min. The circumferential GFB temperatures showed the maximum temperatures at the loaded zone and the minimum temperatures in the unloaded zone. The increasing cooling flow effectively reduced both the rotor and GFB temperatures, showing a dramatic decrease with the smallest amount of cooling flow. GFB friction torque was measured for two test cases for the static load of 80 N at a rotor speed of 10 krpm: 1) A lift-off and touch-down operating cycle for increasing heater temperatures without the cooling flow, and 2) a continuous operation for the heater temperature of 400 °C with increasing cooling flows. In test case 1, the GFB friction torque decreased for higher heater temperatures due to a larger thermal expansion of the bearing housing than the rotor’s. In test case 2, the GFB friction torque decreased with increasing cooling flows due to strong cooling effects on the rotor temperature. The results imply that the tangential air injection increased the GFB clearance by directly cooling the rotor and effectively alleviating the rotor expansion; hence, the scheme is capable of an effective cooling for high temperature GFB applications, such as micro gas turbines.