非接触密封失稳振动分析与结构优化

为了提高非接触密封系统的密封稳定性，针对浮动环系统的振动特性，提出基于预应力模态分析和振动测试试验相融合的固有频率漂移优化设计方案.从气膜刚度方程与浮动环系统的振动方程出发，建立气膜刚度稳定性与浮动环系统振动的理论关系式.依据密封设计要求，建立浮动环系统模态分析模型；搭建浮动环系统的振动特性测试平台，多次测试多级离散化操作参数下浮动环系统的轴向振动加速度响应.试验数据显示，当转速为7 000 r/min时，加速度响应出现峰值，与浮动环系统预应力模态分析下的轴向共振模态频率具有较高的吻合度；基于分析及试验结果，对非接触密封浮动环系统提出提高弹簧刚度的优化方案，并进行验证.优化结果表明，浮动环系统的加速度响应峰值得以消除，避免了非接触密封失稳；相对于未优化前，加速度响应幅值有效降低了12%，密封性能更加稳定.
Abstract: A natural frequencies drift optimization method of the floating ring system based on the combination of pre-stressed mode analysis and vibration test was proposed in order to improve the stability of the non-contact seal. The relationship between the stability of film stiffness and the vibration of floating ring system was derived from the gas film stiffness equation and vibration equation of floating ring system. The mode analysis model of floating ring system was established and the vibration characteristic test platform of the floating ring system was constructed according to the existing designed conditions. The vibration responses and trend of floating ring system were obtained under multi-stage discretization operating parameters. A peak of the acceleration response occurred at 7 000 r/min, which accorded with the axial resonance mode frequency under the pre-stressed mode analysis of the floating ring system. The optimization method of improving the spring stiffness was proposed and verified based on the analysis and test results. The optimization results show that the peak of the acceleration response eliminated and the instability of non-contact seal was avoided. The acceleration amplitude effectively reduced by 12% and the sealing performed more stable.