具有初始弯曲的1000MW汽轮机低压转子的振动特征分析

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振动与冲击 ›› 2014, Vol. 33 ›› Issue (17) : 150-153.

论文

具有初始弯曲的1000MW汽轮机低压转子的振动特征分析

吴文青，谢诞梅，杨毅，胡鹏飞

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ANALYSIS OF VIBRATION BEHAVIOR FOR THE BENT ROTOR OF A 1000MW TURBINE

Van Thanh Ngo，Danmei Xie，Yi Yang, Pengfei Hu

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摘要

近年来，1000MW超超临界汽轮发电机组在中国得到快速发展。然而，运行经验显示，1000MW超超临界汽轮发电机组普遍存在振动偏大的现象，尤其低压转子两端的振动比较突出。转子振动的原因有很多，质量不平衡和轴系弯曲均会随着转子的每一次旋转周期性地给予转子一个固定的激振力。本文以某1000MW超超临界汽轮机的低压#2转子为例，利用有限元的方法研究其弯曲振动特性，并对质量不平衡和弯轴故障引起的振动特征进行了对比分析。计算结果显示，转子在定速下旋转会出现因质量不平衡或弯曲而产生的涡动，当转子支撑在各向同性轴承上时，无论是激振力是正向或反向涡动，所引起的振动响应均为正进动；而当转子支撑在各向异性轴承上时，无论是激振力是正向或反向涡动，所引起的振动响应均将是为反进动。当交叉刚度呈异向（一个为正，一个为负）时，无论是否存在阻尼，转子将出现不稳定。

Abstract

Recently，large capacity steam turbines have come into wider use and have been designed to perform at even higher performance specifications. As we all know, it’s hard to maintain the concentricity of rotor-bearing system during operating, especially for multi-rotors within specified levels of vibration. Rotor vibration could be caused by many reasons. Mass unbalance and bent shaft are amongst the most frequently occurring of these reasons. Mass unbalance and bent shafts both give force excitation at a frequency corresponding to once per revolution. Taking a LP B rotor of a 1000MW USC steam turbine as an example, this paper studies the lateral vibration of the LP B rotor based on finite element. Responses of mass unbalance and bent shaft are analyzed and compared. Calculation results show that, if the rotor is spinning at a constant speed, then it exhibits whirl and it is impossible to deduce whether that whirl is caused by an out-of-balance or a bent. The response of the rotor supported by isotropic bearings, only forward whirl is excited whereas both forward and backward whirl are excited when rotor supported by anisotropic bearings. In case cross coupling stiffness, one cross- coupling term is positive and the other is negative, can make rotor unstable despite the presence of damping.

导出引用

吴文青;谢诞梅;杨毅;胡鹏飞. 具有初始弯曲的1000MW汽轮机低压转子的振动特征分析[J]. 振动与冲击, 2014, 33(17): 150-153

Van Thanh Ngo;Danmei Xie;Yi Yang;Pengfei Hu. ANALYSIS OF VIBRATION BEHAVIOR FOR THE BENT ROTOR OF A 1000MW TURBINE [J]. Journal of Vibration and Shock, 2014, 33(17): 150-153