含端面封严的转子动力学建模及振动特性分析

Dynamic Modeling and Vibration Characteristics Analysis of Rotor with End Face Seal

关键词:  航空发动机  石墨端面封严  偏置盘转子  非线性激励  振动响应  稳定性

Key words:  Aero-engine  End face sealing of graphite  Offset disc rotor  Nonlinear excitation  Vibration response  Stability

摘要:

石墨端面封严是航空发动机中广泛采用的一种接触式封严结构，其在工作时由于转子摆动将不可避免地对转子产生非线性激励载荷。为揭示此种端面接触式封严对转子的动力学影响，以偏置盘转子-封严系统为对象，考虑转子摆动的影响推导了端面封严的非线性激励载荷，建立了含端面封严的偏置盘转子系统的非线性动力学方程，结合数值分析详细研究了端面封严诱发的转子非线性动力学响应及稳定性特征。结果表明，端面封严载荷对转子系统始终做正功，当系统阻尼不足以耗散封严载荷输入的振动能量时，转子振幅将逐渐发散并表现出失稳特征，此时转子频域响应由转子模态成分主导。通过对关键参数影响分析，发现减小封严结构接触半径、摩擦系数、轴向刚度或提高系统阻尼有利于提升转子稳定性。

Abstract:

End face seal of graphite is a kind of contact seal structure widely used in aero-engines， and it will inevitably produce nonlinear excitation load on the rotor due to the rotor swing at work. In order to reveal the influence of such end-face contact seal on rotor dynamics， this paper takes the offset disc rotor-sealing system as the object， deduces the nonlinear excitation load of end-face seal considering the influence of rotor swing， establishes the nonlinear dynamic equation of the offset disc rotor system with end-face seal， and studies in detail the nonlinear dynamic response and stability characteristics of the rotor induced by end-face seal combined with numerical analysis. The results show that the end face seal load always makes a positive work on the rotor system. When the system damping is insufficient to dissipate the vibration energy input by the seal load， the rotor amplitude will gradually diverge and show instability characteristics. At this time， the rotor frequency domain response is dominated by the rotor modal components. By analyzing the influence of key parameters， it is found that reducing the contact radius of sealing structure， friction coefficient， axial stiffness or improving system damping is beneficial to improving rotor stability.