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以某国产大型汽轮机组为例,利用传递矩阵法原理和相关的软件包,计算并分析了轴系的稳定性和不平衡响应,求出了系统的阻尼临界转速,并研究了轴承标高变化对负荷分配的影响以及扭振特性等,涉及汽轮机轴系动力特性的大多数领域。结果表明,分析方法完全满足工程精度要求,可以用于大型汽轮机组轴系的动力特性分析。 相似文献
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大型汽轮发电机组是一个多支撑结构,轴系中任一轴承标高的变化都将影响所有轴承的载荷分配,因此研究轴承栽荷灵敏度对机组稳定运行非常重要.利用传递矩阵法计算了某1 000 MW机组轴系扬度曲线及轴承载荷与灵敏度,对比分析了计算扬度曲线与实测曲线,两者在轴系中问吻合较好.两端差别较大.由计算扬度曲线与实测扬度曲线分别计算了轴系各轴承载荷分布情况,由计算扬度值得出的同根转子轴承载荷分配较为均匀.结合载荷对标高变化的灵敏度分析了该机组轴承栽荷对标高变化规律,端部轴承对裁荷的灵敏度较小,而中间部位较大.分析结果对该机组运行有指导意义. 相似文献
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基于汽轮发电机组轴系对中检测数据,应用传递矩阵方法建立了轴承载荷识别模型,首先由对中数据识别轴承标高,然后由轴承标高计算轴承载荷.以某350MW汽轮发电机组为例进行了计算,分析了张口和高低差对轴承载荷的影响以及3种不同对中状态下的载荷分配.结果表明:该方法可有效地由轴系中心检测数据识别轴承标高和轴承栽荷;理想对中状态下,各对轮处的张口和高低差为0;检修后低速盘车状态下,1号、2号轴承顶轴油压相近,2个轴承的载荷分配基本均匀;满负荷运转状态下,轴系振动稳定,消除了突发性不稳定振动现象. 相似文献
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综合考虑导轴承和推力轴承的支撑刚度对轴系的横—纵—扭耦合影响,应用Ansys Workbench软件建立了悬式三支点水轮发电机组轴系的三维有限元模型,采用Block Lanczos模态分析法分析了轴系的固有频率及其振型,借助Design Exploration优化设计模块计算了机组实际运行时轴系的预应力模态,获得了水流冲击和转速变化等因素对机组轴系固有频率值的影响规律。结果表明,机组在运行过程中转速变化对轴系的低阶横向振动频率影响较大,而对其扭转振动频率影响很小。 相似文献
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针对国产600MW汽轮发电机组运行中普遍存在的轴系异常振动问题,分析了振动现象、振动特征、振动机理及其原因,并对现场动平衡问题的处理方法进行了总结.结果表明:国产600MW高中压转子由于结构不对称存在较大的振型干扰,现场对转子进行动平衡时应考虑各阶振型的干扰系数,尤其是一阶配重对二阶振型的影响;部分机组低压转子轴承座振动超标的原因为采用坐缸式轴承座的支承刚度不足,现场可以通过精细动平衡来消除;发电机转子振动主要呈现三阶振型,现场校正三阶不平衡的方法就是在低-发对轮或发-励对轮上加重,且在动平衡分析时应注意区分振型畸变;集电小轴的振动受发-励对轮的安装工况影响较大,现场对其进行动平衡分析时应考虑发-励对轮下张口对加重响应的影响. 相似文献
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Investigation of high‐speed shaft bearing loads in wind turbine gearboxes through dynamometer testing 下载免费PDF全文
Many wind turbine gearboxes require repair or replacement well before reaching the end of their design life. The most common failure is bearing axial cracks, commonly called white etching cracks (WECs), which typically occur in the inner raceways of the high‐speed parallel‐stage rolling element bearings. Although the root causes of WECs are debated, one theory is that they are related to routine dynamic operating conditions and occasional transient events prevalent in wind turbines that can result in high bearing stress and sliding of the rolling elements. This paper examined wind turbine gearbox high‐speed shaft bearing loads and stresses through modeling and full‐scale dynamometer testing. Bearing outer race loads were directly measured and predicted using a variety of modeling tools in normal operations, misaligned conditions, and transient events particularly prone to bearing sliding. Test data and models of bearing loads were well correlated. Neither operational misalignment due to rotor moments nor static generator misalignment affected the bearing loads when compared with pure‐torque conditions. Thus, it is not likely that generator misalignment is a causal factor of WECs. In contrast, during transient events, the bearings experienced alternating periods of high stress, torque reversals, and loads under the minimum requisite at high rotating speeds while showing indications of sliding, all of which could be related to the formation of WECs. 相似文献
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Conventional Savonius rotors have high coefficient of static torque at certain rotor angles and a negative coefficient of static torque from 135° to 165° and from 315° to 345° in one cycle of 360°. In order to decrease this variation in static torque from 0° to 360°, a helical Savonius rotor with a twist of 90° is proposed. In this study, tests on helical Savonius rotors are conducted in an open jet wind tunnel. Coefficient of static torque, coefficient of torque and coefficient of power for each helical Savonius rotor are measured. The performance of helical rotor with shaft between the end plates and helical rotor without shaft between the end plates at different overlap ratios namely 0.0, 0.1 and 0.16 is compared. Helical Savonius rotor without shaft is also compared with the performance of the conventional Savonius rotor. The results indicate that all the helical Savonius rotors have positive coefficient of static torque at all the rotor angles. The helical rotors with shaft have lower coefficient of power than the helical rotors without shaft. Helical rotor without shaft at an overlap ratio of 0.0 and an aspect ratio of 0.88 is found to have almost the same coefficient of power when compared with the conventional Savonius rotor. Correlation for coefficient of torque and power is developed for helical Savonius rotor for a range of Reynolds numbers studied. 相似文献
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Shaft signals of electric rotating machines offer potentials for defect detection. The signals are affected by many factors. This study specifically focuses on how eccentricities affect shaft signals through theoretical predictions and tests conducted on windingless rotors. Windingless rotors imply currentless rotors. For symmetrical synchronous machines running at steady synchronous speeds, the induced rotor currents are zero, while harmonics are neglected. One advantage in experiments for this study is that air gaps can be shimmed accurately at standstill without end brackets; certain tests can be conducted at standstill without facing unmanageable locked-rotor currents for the test machines. Shaft signals decrease when the rotor of a machine closely situates at the center of stator bore. Shaft signals increase under greater eccentricities when stator and rotor axes are parallel. Tilted rotors reduce shaft signals. Even when there are no rotor windings, inherent positional characteristics exists. This characteristic produces cyclic shaft-signal components that are related to rotor revolutions 相似文献
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Improving the reliability of wind turbines (WT) is an essential component in the bid to minimize the cost of energy, especially for offshore wind because of the difficulties associated with access for maintenance. Numerous studies have shown that WT gearbox and generator failure rates are unacceptably high, particularly given the long downtime incurred per failure. There is evidence that bearing failures of the gearbox high‐speed stage (HSS) and generator account for a significant proportion of these failures. However, the root causes of these failure data are not known, and there is therefore a need for fundamental computational studies to support the valuable ‘top down’ reliability analyses. In this paper, a real (proprietary) 2 MW geared WT was modelled to compute the gearbox–generator misalignment and predict the impact of this misalignment upon the gearbox HSS and generator bearings. At rated torque, misalignment between the gearbox and generator of 8500 µm was seen. For the 2 MW WT analysed, the computational data show that the L10 fatigue lives of the gearbox HSS bearings were not significantly affected by this misalignment but that the L10 fatigue lives of the generator bearings, particularly the drive‐end bearing, could be significantly reduced. It is proposed to apply a nominal offset to the generator to reduce the misalignment under operation, thereby reducing the loading on the gearbox HSS and generator bearings. The value of performing integrated system analyses has been demonstrated, and a robust methodology has been outlined. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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利用焊接方法制造大型汽轮机转子已成为电力装备制造业的主要方向,通过测量焊接转子模拟件接头处的残余应力,对于转子设计、优化焊接与热处理工艺、评估服役状态都具有重要的参考意义。测试了25Cr2N i2MoV钢核电转子模拟件外圆、内圆、剖面处热处理前后的残余应力分布,发现转子深窄间隙接头处存在较为显著的轴向压应力,内、外圈在热处理前均有较大的切向拉应力;经过热处理,残余应力大大降低,且保持较好的应力状态。重复性测量的数据稳定性较好,反映出加工过程的高稳定性。 相似文献
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300MW合缸汽轮机组的高中压转子是国内目前运行汽轮机的较大转子之一,此类转子轴的直径大、跨距长,校直难度较大。本文论述了华北电科院使用可移动式直轴设备,采用目前较先进的松弛法直轴,在电厂厂房检修场地内成功地完成了某电厂6号机组高中压转子的直轴工作,为机组的抢修节约了时间,其经济效益和社会效益巨大。 相似文献