稳态热度场对转子系统临界转速的影响

汽轮机转子系统在频繁启停时，将产生较大的热应力和热变形，使转子系统的振动特性发生变化。采用有限单元法，利用热-结构-动力学耦合理论，对稳态温度场对某汽轮机转子系统的临界转速的影响进行了探讨。结果表明，随着转子系统轴向温差和径向温差的增大，热变形程度逐渐增大，系统振动的临界转速逐渐降低。稳态温度场对低阶临界转速的影响较大，而对于高阶临界转速的影响较小，特别对第一阶临界转速具有较大的影响，但对各阶临界转速的振型影响很小。在对转子系统的振动研究中，不应当忽略温度的影响。

Effect of Steady Thermal Field on Critical Speeds of a Rotor System

Based on finite element method ( FEM) , the effects of thermal field on critical speeds of certain steam turbine rotor system are studied using coupling theory of thermal-structure-dynamics. The results show that, with the increasing of axial and radial temperature difference, the thermal distortion of rotor increases and the critical speeds of rotor decreases. The thermal field has strong effect on lower order critical speeds, especially the first order critical speed, but has little effect on higher order critical speeds. On the other hand, the effect of thermal field on vibration modal shapes is very small. In practical vibration examination, the effect of temperature distribution on vibration of rotor system should not be ignored.