稳态温度场对转子系统振动特性的影响

热弯曲是工程实际中常见的转子故障.采用有限元法,利用热-结构-动力学耦合理论,探讨了稳态温度场对某汽轮机转子系统的振动特性的影响.对比研究了不平衡响应、热弯曲响应以及不平衡和热弯曲耦合响应,讨论了稳态温度场、转子系统的工作转速等因素对转子-轴承系统热振动特性的影响,找出了影响其热振动特性的敏感参数.结果表明,由于热弯曲的产生,转子系统的刚度重新分布,导致了其热振动的一阶临界转速显著降低,同时改变了振动的平衡位置,使转子系统围绕新的平衡位置做周期性运动.计算结果为转子-轴承系统的设计和热弯曲故障诊断提供了理论依据.

Effects of Steady Temperature Field on Vibrational Characteristics of a Rotor System

Thermal buckling is a common fault found in rotor system.The effect of steady temperature field on the vibrational characteristics of rotor system of a certain turbine unit was studied by means of FEM and the coupling theory of thermal-structure dynamics.Comparing the unbalance response,thermal buckling response and the response coupling both together,the effects of steady temperature field,operational rotational speed on thermal vibration characteristics were discussed in detail with the sensitive parameters affecting thermal vibration found out.The results showed that the stiffness matrix of the rotor system is redistributed because of thermal buckling,thus resulting in the significant decrease in the first critical speed of the rotor system due to the thermal vibration.At the same time,the thermal buckling changes the balance position and causes the rotor system to vibrate periodically around a new balance position.The calculated results offer a theoretical foundation on which the design and fault diagnosis of rotor-bearing system are both available to avoid great thermal vibration.