【作者】 范雷雷；

【导师】 杨建刚；

【作者基本信息】 东南大学 ， 动力机械及工程， 2005， 硕士

【摘要】 振动是影响汽轮发电机组安全稳定运行的关键因素之一。不平衡是最常见的振动故障,约占故障总量的80%以上。如何减少开机次数,提高动平衡效率一直是人们研究热点。由于不平衡故障的高发性及复杂性,转子系统不平衡响应特性也是目前转子动力学领域广泛研究的课题之一。本文针对存在质量偏心的Jeffcott转子,分析了不平衡引起振动的机理。并介绍了轴系和支撑系统的模化方法,运用Riccati传递矩阵法建立计算模型,求解不平衡响应。在Riccati传递矩阵法建立的计算模型基础上,本文用Matlab编制了计算不平衡响应的程序,利用开发的程序,我们对200MW汽轮发电机组的高压转子不平衡响应特性进行了计算分析,得出了一些有益的结论。　　我们针对在现场动平衡工作中发现的几起异常现象,建立了转子模型,对异常现象进行了计算分析。分析结果表明:转子两端支撑刚度不对称引起了这些异常现象。在支撑刚度不对称情况下,在转子上加对称不平衡量,不仅激发一阶分量,同时还激发出明显的二阶分量,同样,加反对称不平衡量,不仅激发二阶分量,同时还激发出明显的一阶分量,转子不平衡响应发生了变化。这一结论对动平衡工作中现场确定加重方式、判断不平衡位置、选择加重面,具有非常重要的工程应用价值。在动平衡工作中我们发现,在大多数情况下,根据垂直振动信号和水平振动信号找出的振动高点位置不同,有时甚至相差很大,而相位是动平衡工作中寻找振动高点的主要依据,这给准确寻找振动高点,提高动平衡效率带来很大的困难。我们对这现象进行了理论分析和计算,认为轴承垂直和水平方向动力特性差异是造成这种现象的主要原因。最后通过试验对转子系统不平衡响应特性进行分析研究。更多还原

【Abstract】 Unbalance is one of the main causes of vibration in turbo-generator unit that may lead to catastrophe failture during operation. It is hot point that enhancing balance efficiency. Because of the frequency complexity of unbalance , the unbalance response characteristics of rotor system is one of the widely researched discussions in the nearly years.Based on the former researches, the Jeffcott rotor system with mass eccentricity is analyzed in this paper. The modeling method of rotor system and bearings are presented, and the unbalance response is resolved by Riccati transfer matrix method. Based on the calculation model set up by Riccati transfer matrix, a kind of program on how to calculate unbalance response is carried out. Useing this kind of program, we make calculation analysis to the unbalance response of high pressure rotor of 200MW turbine-generator, some useful conclusions have been made also.Two examples are presented as examples to introduce the abnormal vibration during balance work. Reasons are analyzed in detail. We conclude that unsymmetric support dynamics is the main reason for this phenomenon. Both the 1st and 2nd vibration mode can be excited simultaneously by symmetric or anti symmetric unbalance distribution. Unbalance response characteristics changes a lot compared with the symmetric support condition. This conclusion is important for rotor balance in the field.Vibration phase is the important parameter to be considered during rotor balance, especially for rotor high-point decision. Due to that in most cases, the phase difference between the vertical phase and the horizontal vibration phase isn’t always 90°, the high-points decided by vibration signals in two direction are usually different. In this paper, a mathematical model and a test rig were set up to research the phase change rule during run up process. We found that unsymmetrical dynamics of bearing in the two directions is the main reason for the phenomenon. We also found that when rotor runs up through the critical speed, not only it’s phase but also the phase difference change acutely.Lastly the unbalance response characteristics are studied with a test rig.更多还原