基于推力轴承作用的透平机械复杂转子耦合系统动力学行为研究

Thrust bearing is often used as the axial support of turbomachinery rotor system. It not only affects the axial displacement and vibration of the rotor, but also has a strong coupling effect on the rotor lateral vibration, like radial bearing. Therefore, it is necessary to study the dynamic behavior of the thrust bearing-rotor system comprehensively and systematically. In this application project, the theoretical model of fluid film thrust bearing for Thermo-Elasto-Hydro-Dynamic lubrication performance calculation is established, and the influence law of rotor axis misalignment on bearing performance of thrust bearing is sorted out. The dynamic behavior equation of thrust bearing-rotor coupling system with multi degrees of freedom is established, and the mechanism of coupling effect between thrust bearing and rotor bending on rotor vibration is analyzed. Based on the static and dynamic parameters identification of thrust bearing under axial loading, the sensitivity of axial and lateral vibration to the amplitude and frequency of axial excitation is proved. A self-healing criterion of axial displacement fault based on auxiliary control of magnetic thrust bearing is constructed, and the action mechanism of axial load offset by magnetic thrust bearing and fluid film thrust bearing is clarified. The purpose of this study is to reveal the strong coupling effect, vibration transmission characteristics and response mapping relationship between thrust bearing and rotor system, to improve the bearing reliability and rotor stability of turbomachinery complex coupling system under thrust bearing effect, and to provide theoretical basis for rotor dynamic design considering the influence of thrust bearing.

推力轴承常被用作透平机械转子系统的轴向支撑，其不仅影响转子轴位移及轴向振动，也同径向轴承一样，对转子弯曲振动产生强烈的耦合作用，因此非常有必要进行全面系统的推力轴承-转子系统动力学行为研究。本申请项目拟通过建立热弹流耦合动力润滑性能计算的滑动推力轴承理论模型，梳理转子轴线偏斜对推力轴承承载性能的影响规律；建立多自由度的推力轴承-转子耦合系统动力学行为方程，剖析推力轴承与转子弯曲的耦合作用对转子振动的影响机理；基于轴向载荷加载辨识推力轴承静动特性参数，探明轴向及横向振动对轴向激励幅值和频率的敏感性；构建基于电磁推力轴承辅助调控的轴位移故障自愈准则，澄清电磁推力轴承与滑动推力轴承共同抵消轴向载荷的作用机制。本研究旨在揭示推力轴承与转子系统之间的强耦合效应、振动传递特性及响应映射关系，提高推力轴承作用下透平机械复杂耦合系统的轴承可靠性及转子稳定性，为考虑推力轴承影响的转子动力学设计提供理论依据。

燃气轮机、汽轮机、离心压缩机、航空发动机等透平机械中具有止推作用的轴承，常被用作转子系统的轴向支承，在轴向载荷作用下其不仅影响转子轴位移及轴向振动，也对转子弯曲振动产生强烈的耦合作用，因此非常有必要进行全面系统地轴向载荷作用下转子-轴承耦合系统动力特性研究。本课题通过建立多自由度的转子-轴承耦合系统动力学行为方程，剖析轴向载荷作用下推力轴承与转子弯曲的耦合作用对转子振动的影响机理，旨在揭示轴向载荷作用下推力轴承与转子系统之间的强耦合效应、振动传递特性及响应映射关系，结合作用在推力轴承上的转子轴向力测试技术开发，提高透平机械复杂耦合系统的轴承可靠性及转子稳定性。.为了揭示推力轴承支承的转子系统复杂振动特性，具体开展的工作如下：.（1）建立了推力轴承“TEHD热-弹-流-动力润滑”性能和油膜动特性计算模型，在轴线偏斜状态下，最大油膜压力、温度和轴瓦温度升高，总的轴承主刚度增加，主阻尼降低，而角刚度减小，角阻尼增大。.（2）基于轴向载荷作用下的推力轴承的角刚度和角阻尼参数，建立了滑动推力轴承轴向支承的转子-轴承耦合系统有限元模型，在推力轴承作用时，转子应变能占比逐渐变小，推力轴承的应变能占比逐渐增大，说明轴向载荷作用下的推力轴承动力特性参数使转子的稳定性增加。.（3）开发了基于应变环仿真与标定的转子轴向力测试技术，设计了带多个轴向凸台周向交错均布的弹性环结构，确定了带温度补偿的四分之一桥II型应变片桥路布置方案。通过仿真与试验标定对比，应变环应变和轴向载荷之间表现出了较好的线性比例关系。试验标定与仿真计算的结果吻合较好。.总之，为保证透平机械的长寿命安全运行，本课题主要研究轴向载荷作用下的透平机械复杂转子-轴承耦合系统振动特性，澄清转子轴线偏斜对推力轴承承载性能的影响以及推力轴承对转子系统动力学行为的作用，为考虑轴向载荷作用下推力轴承影响的转子动力学设计提供理论依据。