船用汽轮机转子盘轴耦合振动特性研究

基于小长径比建模理论,建立了盘轴耦合转子的有限元模型,并对采用工程实际的斜切方式和轮盘单元等不同建模方法下船用汽轮机转子的振动特性进行了分析,给出了较为系统的、适用于小长径比、短粗转子等结构的建模方法对转子系统振动特性的影响规律。不同的建模方法会对转子盘轴耦合振动特性计算结果有显著影响。轮盘单元会使得转子轴承系统出现附加的振型,表现为轮盘与转轴的耦合模态振型,轮盘单元建模的计算方法能准确描述盘轴耦合转子的振动特性。研究结果表明,对于厚度较大的轮盘,轮盘对转子耦合振动的影响较小,工程常用的斜切建模会引入附加刚度,引起较大求解误差,且这种误差随着轮盘厚度的减小而逐渐降低。

Study on Vibration Characteristics of Marine Steam Turbine Rotor Shaft Coupling With Disk

Base on small aspect ratio modeling theory, the finite element of rotor shaft coupling with disk was established, and the vibration characteristics of marine steam turbine rotor were analyzed with different modeling methods such as oblique cutting way and disk unit. Then, the significant influences of different modeling methods on the vibration characteristics of the rotor system were studied. The additional modes of rotor bearing system generated by disk unit represented as coupling vibration mode between disk and rotor shaft. The calculation method based on disk-unit model accurately described the vibration characteristics of the rotor shaft coupling with disk. For thicker disk, the disk had less effect on the rotor coupling vibration. The oblique cutting model commonly used in engineering generated additional stiffness and caused larger error in the solving process. This kind of error gradually reduced with the decreasing of the disk thickness.