中文摘要：

针对电磁轴承支承的高速透平膨胀机转子系统,利用ANSYS软件建立详细的三维实体模型,并采用适当方法生成合理的有限元模型,对电磁轴承在转子系统中的模拟和作用进行探索。使用一组实测的控制器参数,结合电磁轴承系统的实际结构和刚度阻尼的计算方法,计算电磁轴承的刚度阻尼系数。并以此为输入参数,经ANSYS模态分析得到该转子系统的前8阶临界转速和模态振型。其中前6阶临界转速远低于系统工作转速,对应为系统的扭转、轴向平动或刚体摆动振动模态;后2阶临界转速接近系统工作转速,对应一阶弯曲振动模态。计算结果表明,系统在现有结构及参数条件下不能按预定的工作转速稳定运转,需要改进设计。由计算结果分析知道,轴向电磁轴承对转子系统动力特性有一定影响,某些情况下不能忽视。理论计算结果与试验情况基本吻合,可为该转子系统设计提供理论依据。此研究思路与方法可作为同类系统动力特性研究的一种参考。

英文摘要：

The three-dimensional solid model of a turbo expander rotor system,supported by active magnetic bearing （AMB）,is established by using ANSYS software.And the correct finite element model built with some appropriate methods is used for modal analysis.The modeling method of the AMB and their effect on the rotor system are explored.A set of measured controller parameters combined with the calculation method for the actual structure and stiffness-damping of the AMB are used to calculate the stiffness and damping coefficients of the AMB.By using these as input parameters,the first eight critical speeds and mode shapes of the rotor system are obtained through ANSYS modal analysis.Each of the first six critical speeds is far lower than the operating speed of the system,corresponding to the vibration modes of torsion,axial translation and rigid swing respectively.The other two critical speeds are close to the operating speed of the system,corresponding to the 1st bending vibration.The calculation results show that the rotor cannot run stably at the scheduled operating speed under the existing structure and parameter conditions,and the design needs improving.It is known from the analysis of the calculation result that the axial active magnetic bearing has certain effect on the dynamic characteristics of the rotor and it should not be ignored in some cases.The theoretical calculation results are basically in accordance with the experimental results.This research provides a theoretical basis for the rotor system design.The ideas and methods can be used as a reference for the study of dynamic characteristics of similar systems.