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| Effect of rod relaxation upon performance degradation of combined rotor for gas turbine |
| SU Yong-lei1,2，WANG Ai-lun1,2，LI Xue-peng2，GAO Si-xiao2， ZHANG Ying-ying2 |
1. State Key Laboratory of High Performance and Complex Manufacturing， Central South University， Changsha 410083， China;
2. College of Mechanical and Electrical Engineering， Central South University， Changsha 410083， China |
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Abstract Combined rotor is the vital part of a gas turbine. It is important to reveal the performance degradation mechanism and assess the performance degradation characteristics of the combined rotor for making maintenance during operation. To reveal the performance degradation mechanism caused by structure degradation, the change rule of pretension force under time-history was obtained with consideration of the rod stress relaxation at high temperature. By defining the degradation degree of combined rotor with the pretension force of rod, degradation level of combined rotor system was evaluated. After calculating the contact stiffness of adjacent disks interface and analyzing the dynamic characteristics of combined rotor considering contact interface, the effect of different degradation level on dynamic characteristics of combined rotor was obtained. The result showed tht temperature was a sensitive parameter for combined rotor degradation, the drift of combined rotor natural frequency was caused by the relaxation of rod, and the relative reduction of the first three order natural frequency for combined rotor differed quite small, which had a linear relationship with degradation degree to some extent．
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Published: 28 June 2014
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拉杆松弛对燃气轮机组合转子性能退化的影响
组合转子作为燃气轮机的核心部件，其性能退化将对整个燃气轮机的性能产生重大影响，揭示组合转子性能退化机理并进行退化特征分析对燃气轮机的可靠运行具有重要意义．为揭示组合转子结构损伤导致的性能退化机理，考虑拉杆螺栓在高温下的应力松弛，得到基于时间历程的拉杆预紧力变化规律；通过拉杆预紧力定义组合转子退化量指标，评估组合转子的退化程度；计算轮盘界面接触刚度，进行考虑接触界面的组合转子动力学分析，进而得到燃气轮机组合转子不同退化量下的动力学特征．结果表明：温度是影响组合转子性能退化的敏感参数；拉杆松弛导致组合转子固有频率漂移，组合转子前3阶固有频率的降低率相差很小，并在一定范围内与退化量呈线性关系．
关键词：
拉杆松弛,
组合转子,
退化量,
接触刚度,
固有频率
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