转子-密封系统中气流激振力的非线性动力学特性分析

在高参数汽轮机组和航空发动机等旋转机械中，转子-密封中的气流激振力对转子非线性动力学特性的影响不容忽视．本研究中建立了转子-密封系统三维流场模型，应用计算流体动力学（CFD）软件对可压缩气流流场进行模拟计算，获得了密封流场特性．由流场计算结果进一步获得了Muszynska气流激振力模型中的相关经验系数，使得此模型更加适用于气流激振力的计算．在对转子一密封系统进行非线性动力学分析过程中应用幂级数展开形式建立了系统幂级数模型．利用平均法得到气流激振力的1：2亚谐共振分岔方程，进一步应用奇异性理论和Hopf分岔理论研究了系统1：2亚谐共振的转迁集和系统超临界Hopf分岔与亚临界Hopf分岔的存在条件．通过参数控制方法抑制了转子-密封系统出现亚临界分岔的出现，使得系统稳定性提高．本文的分析结果对工程设计和操作具有一定的指导作用和意义．

Nonlinear dynamic characteristics analysis of the gas exciting force in the rotor-seal system

The flow field of 3-D rotor-seal system was developed, and the characteristics of compressible gas flied for the system were researched by Computational Fluid Dynamics (CFD) technology. The empirical parameters and experimental parameters of the Muszynska gas exciting force model were further identified by the computational results, which made it more suitable for the rotor-seal system. The nonlinear dynamic analysis of the rotor-seal system applied the power series model of the rotor-seal system obtained by power series expansion. The multiple scale method was used to obtain the bifurcation equations of the rotor-seal system in the 1:2 subharmonic resonance case. Based on the singularity theory and Hopf theory, the 1:2 subharmonic resonance transition sets and the existing condition of the supercritical Hopf bifurcation and subcritical Hopf bifurcation were obtained. The subcritical Hopf bifurcation of the rotor-seal system was inhibited by parameter control to improve the system stability.