百万等级核电半速汽轮发电机组低压转子轴承支撑刚度的研究

建立了汽轮机低压转子落地式轴承座刚度分析有限元模型,采用三维有限元软件Ansys分析了使用弹簧基础的百万等级核电半速汽轮发电机组低压转子落地式轴承座的刚度,并在此基础上计算和分析了轴承座刚度在一定范围内变化时对大型汽轮机低压转子临界转速的影响．结果表明：利用汽轮机低压转子落地式轴承座刚度分析有限元模型计算得到的低压转子轴承座刚度与经验数值量级相同,但大小有一定差异．汽轮机低压转子临界转速对低于一定数值的落地式轴承座支撑刚度变化更敏感,因此在设计时应保证足够大的轴承座刚度．     

某中速双燃料机主轴承座强度校核

针对某新型中速双燃料机轴承座,为了评估设计的安全型,首先采用动力学软件进行载荷计算,确定出危险工况.然后采用有限元方法考察了主轴承座和主轴承盖的应力、疲劳以及主轴承盖和主轴承座的接触情况,保证了结构的可靠性,为轴承座的设计研发提供很好的参考.     

发动机主轴承座结构强度分析研究

建立了包括缸体、框架、轴瓦、曲轴及连接螺栓的发动机主轴承座网格模型,通过指定不同的接触区域、接触条件、载荷、约束边界条件及多点约束,分别建立了螺栓预紧、轴瓦过盈、曲轴动压力及热负荷四种工况主轴承座强度分析有限元模型。采用二阶修正单元并通过接触主从面上单元的对应性来保证计算精度和收敛性,采用小滑移接触算法计算出各工况下主轴承座的应力和变形情况,根据计算结果,对主轴承座的强度、变形、滑移表面的滑动以及轴瓦背面的压力分布进行了评价,对主轴承座结构提出了改进意见,改进方案满足结构设计要求。     

基于ANSYS Workbench的轴承座分析计算

轴承座是重要的轴承连接元件,利用ANSYS Workbench仿真平台,在设计基础上对轴承座结构进行有限元分析,验证模型结构设计的合理性及安全性.     

船舶Ⅴ型柴油机曲轴多体动力学分析

针对Ⅴ型柴油机曲轴系统,将有限元法和多体动力学法结合一起,进行虚拟仿真计算分析.首先通过三维软件和有限元软件建立曲轴、轴承座及活塞等多体动力学模型,模拟发动机实际工况,通过多体动力学仿真分析得出曲轴加速度、速度和位移等数据.通过计算得出,采用有限元和多体仿真结合的手段,能够有效模拟柴油机曲轴动力学特性.     

船舶V型柴油机曲轴多体动力学分析

针对V型柴油机曲轴系统,将有限元法和多体动力学法结合一起,进行虚拟仿真计算分析。首先通过三维软件和有限元软件建立曲轴、轴承座及活塞等多体动力学模型,模拟发动机实际工况,通过多体动力学仿真分析得出曲轴加速度、速度和位移等数据。通过计算得出,采用有限元和多体仿真结合的手段,能够有效模拟柴油机曲轴动力学特性。     

模态分析技术在轴承箱动力学特性改造中的应用

针对某汽轮发电机组在电厂现场运行中存在低压缸瓦振超标,带负荷过程中瓦振波动较大的现象,采用模态分析技术对轴承座进行动力学特性诊断分析和动力修改。试验获得了轴承座的动刚度、模态振型、频率。通过试验确认轴承座的固有频率在运行频率范围内避开率低,动刚度偏低是引起轴承瓦振偏大的主要原因。采用有限元数值模型,对轴承座进行了动力学修改,确定了轴承座结构改进的方案。最后通过轴承座动刚度试验,验证了改进方案的有效性。轴承座改造后机组实际运行中振动特性得到明显改善。     

大功率V型柴油机主轴承座结构强度模拟分析

建立了包括机体、主轴承座、曲轴、轴瓦及紧固螺栓的大功率V型柴油机主轴承座有限元分析模型,分别对螺栓预紧、轴瓦过盈、动压力三种工况下,主轴承座的应力和疲劳、轴瓦背压以及主轴承孔变形等情况进行分析。进一步的疲劳分析表明:设计方案中的主轴承座满足结构强度要求。     

一种低速机主轴承轴瓦安装挤压点数值计算方法

针对低速机新机型的研发,需要对主轴承的轴瓦进行挤压点安装实验,通过有限元数值计算方法,提取结果中主轴承盖与轴承座之间的接触开口与变化,然后通过数据处理得到挤压点对应的螺栓液压拉伸器泵紧压力,从而准确地计算得到主轴承轴瓦的安装挤压点,节省了实验成本,提高了研发效率。     

WP7柴油机曲轴系的多体动力学分析

采用AVL/EXCITE-PU与ABAQUS软件,基于曲轴系多体动力学,对WP7柴油机进行模拟仿真,计算主轴承座轴瓦的反力;同时根据扭转振动的计算结果与测试数据的比较,进行有限元模型的验证与标定,从而获得机体结构噪声的主要激励源数据;通过动力学仿真,得出选用合适、有效的减振器可以降低轴系的最大应力,从而提高疲劳安全系数的结论。     

Application of the ensemble empirical mode decomposition and Hilbert transform to pedestal looseness study of direct-drive wind turbine

The fault signal problems of wind turbine are non-linear and non-stationary, thus it is difficult to obtain the obvious fault features. In this study, a time-frequency method based on EEMD (ensemble empirical mode decomposition) and Hilbert transform is presented to investigate the bearing pedestal looseness fault of direct-drive wind turbine. The real vibration signals are analyzed using IMFs (intrinsic mode functions) extracted by ensemble empirical mode decomposition and Hilbert spectrum in the proposed method. The experimental results indicate that the proposed method is effective to extract the fault features of bearing pedestal looseness of wind turbine. And the results also demonstrate that fault features of front bearing pedestal looseness are different from rear bearing pedestal looseness with the same looseness gap. The fluctuation of rotational frequency increases with the occurrence of front bearing pedestal looseness fault, especially the half rotational frequency and high-frequency components, and the shaft orbit is complex. Besides, we found that when the rear bearing pedestal is loosen, the fluctuation of rotational frequency also increases, and the half rotational frequency component can be found. But for the high-frequency components, it is not obvious, and the shaft orbit is an approximate ellipse. Although the fault features of front and rear bearing pedestal looseness are obvious, the powers generated by wind turbine generator only change slightly.     

125MW汽轮机振动故障处理

通过对125MW汽轮发电机组振动的原因分析，查明了振动是由于动静碰摩、轴承座刚度及质量不平衡引起，采取有效措施取得良好的效果。     

某燃气轮机发电机组公共底座模态分析

建立了某燃气轮机发电机组公共底座精细模型,通过有限元计算,对模型进行了优化设计,通过对公共底座自由状态及实际安装状态下的振动模态分析,获得了各阶模态参数,进而验证了发电机组公共底座设计刚度及结构的合理性。     

联轴器不对中状态对船舶轴系动力学特性影响的试验

针对某船舶高速轴系不对中状态对轴系振动的影响,建立涡轮转子-传动轴-太阳轮转子试验模型,通过调整轴承支座的标高来模拟平行不对中和转角不对中量,进行多次升降速试验获得靠近轴承处的转子的振动位移。研究表明:不同的联轴器不对中状态对轴系的临界转速没有影响;在工作转速4 200 r/min时,不同联轴器对中状态下轴系各测点基频振动幅值变化很小,靠近套齿联轴器的太阳轮右侧轴承处转子2倍频振动明显大于左侧轴承处的振动;整体抬高太阳轮轴系标高对2倍频振动的影响较小;太阳轮左侧轴承支座标高降低时各轴承处2倍频振动幅值均有一定程度的增大;降低涡轮驱动端轴承支座的标高,轴系2倍频振动幅值整体增大;各对中状态下所有测点振动幅值的计算值与试验测量值的平均偏差小于20%,不同的对中状态对涡轮机转子的振动影响均小于对太阳轮转子的影响。     

大型汽轮机轴承支撑刚度研究

汽轮机组轴承支撑刚度对轴系临界转速有较大影响,长期以来一直依靠实测才能获得精确的轴承支撑刚度值。采用三维有限元非线性数值仿真技术对各典型汽轮机组的轴承支撑刚度进行分析和研究,探索出可行的轴承支撑刚度计算方法。并根据研究成果提出在汽轮机设计选型时须提前考虑轴承以及轴承支撑结构的特性,以保证汽轮机组轴系的安全稳定。此法避免了轴承支撑刚度现场实测所带来的费用、时间及与设计脱节的问题,为研发新型轴承提供了有力的技术支持,是轴承支撑刚度设计计算手段的提升。     

某型工业汽轮机轴承箱关键制造技术研究

文章在对某型工业汽轮机轴承箱结构进行分析的基础上,对轴承箱的工艺流程、制造难点等问题进行了深入探讨,并进一步对轴承箱中的关键加工环节的关键加工技术进行了分析研究,制定出了合理有效的加工制造策略,为工业汽轮机轴承箱的加工制造提供了系统全面的技术参考。     

An engineering condition indicator for condition monitoring of wind turbine bearings

Condition monitoring (CM) of wind turbine becomes significantly important part of wind farms in order to cut down operation and maintenance costs. The large amount of CM system vibration data collected from wind turbines are posing challenges to operators in signal processing. It is crucial to design sensitive and reliable condition indicator (CI) in wind turbine CM system. Bearing plays an important role in wind turbine because of its high impact on downtime and component replacement. CIs for wind turbine bearing monitoring are reviewed in the paper, and the advantages and disadvantages of these indicators are discussed in detail. A new engineering CI (ECI), which combined the energy and kurtosis representation of the vibration signal, is proposed to meet the requirement of easy applicability and early detection in wind turbine bearing monitoring. The quantitative threshold setting method of the ECI is provided for wind turbine CM practice. The bearing run‐to‐failure experiment data analysis demonstrates that ECI can evaluate the overall condition and is sensitive to incipient fault of bearing. The effectiveness in engineering of ECI is validated though a certain amount of real‐world wind turbine generator and gearbox bearing vibration data.     

国产300MW汽轮机4号轴承不稳定振动问题研究

在对国产300MW汽轮机低压转子与轴承系统的结构特点分析基础上,结合大量现场试验研究,分析了300MW汽轮机4号轴承不稳定振动的特点。主要从真空变化、轴封蒸汽参数变化以及负荷、轴承标高等的变化对4号轴承不稳定振动的影响加以分析,总结了引起4号轴承不稳定振动的原因,并提出了控制4号轴承不稳定振动的运行与维护措施。     

Fault diagnosis of low-speed rolling bearing based on weighted reconstruction of vibration envelopes

The main bearing supports the rotation of the main shaft of a wind turbine. It bears heavy dead weights as well as variable speed dynamic loading during operations; thus, it is a vulnerable part in a wind turbine drive train. Because of the low speed and time-varying operations of the main bearing, vibrations generated by bearing faults are often weak in response amplitudes, low in frequency range, and smeared in damage feature energy. As a result, the applicability of the conventional acceleration envelope analysis (AEA) technique, a traditionally effective technology for bearing fault diagnosis, is limited in such cases. In order to resolve this, a modified AEA method specially designed for bearings with low and variable speed operation is proposed in this paper. First, the structural response is decomposed by means of variational mode decomposition (VMD) for the low frequency components to form a series of band-limited intrinsic mode functions (BLIMFs). Next, weighting factors are determined for the BLIMFs by defined energy ratios. Finally, a new envelope is reconstructed by weighting the envelopes of each BLIMF for bearing fault diagnosis. The effectiveness and practicality of the proposed method for the diagnosis of main bearing faults in wind turbines is verified through the analysis of measured data from a wind turbine in the field. The proposed method provides an effective way for bearing fault diagnosis at low and variable rotational speeds.     

表面硬化滚道风电主轴轴承的疲劳寿命分析

建立一种针对表面硬化滚道三排圆柱滚子风电主轴轴承的疲劳寿命分析方法。首先,在卡迪尔坐标系中建立三排圆柱滚子风电主轴轴承的5自由度力学模型,分析计算在外部5个方向载荷联合作用下轴承的内部滚子载荷分布;然后,建立圆柱滚子与表面硬化滚道之间的弹塑性接触有限元模型,计算得到滚子接触载荷作用下滚道次表面的脉动应力分布;最后,根据Goodman方程将滚道脉动应力幅值转化为交变应力幅值,运用Basquin应力-寿命理论计算得到风电主轴轴承的疲劳寿命。结果表明,轴承的下风向外圈滚道承受来自风轮的推力载荷,其疲劳寿命最短;径向外圈滚道承受风轮的重力载荷,其疲劳寿命最长。轴承的疲劳寿命取决于下风向滚道。