浮环密封运动机理及对轴系稳定性的影响

Floating ring seals movement mechanism and its influence on stability of a rotor system

浮环密封是引起轴系失稳的重要因素之一。建立浮环密封和转子瞬时运动关系,考虑温度影响,基于有限单元法求解瞬态流体动压力。利用摄动法求解锁死条件下浮环密封动力学系数,并与试验对比。结合非线性摩擦力和数值计算特点,提出浮环锁死动力学条件。建立浮环和转子耦合动力学模型,考虑瞬态流体动压力和摩擦力,研究浮环运动机理及相关因素。结果表明在小偏心率条件下,浮环负交叉刚度远大于主刚度;摩擦力越小、转速越高,锁死位置偏心率越小;锁死位置偏心较小时,浮环密封易引发轴系半频失稳现象,与工程实际相符合。

Floating ring seals are one of important factors causing rotors to be unstable.Here,the relation between floating ring seals and rotor transient motion was established.The transient hydrodynamic pressure was solved with FEM considering thermal effect.The floating ring seals＇dynamic coefficients were solved with the perturbation method when the seals were locked,and they were compared with test results.Based on characteristics of nonlinear friction and numerical calculation,dynamic conditions for the locked-seals were proposed.Floating ring seals and rotors＇coupled transient dynamic models were established considering transient hydrodynamic pressure and friction to study the movement mechanism of seals and the corresponding factors.The results showed that under conditions of small eccentricity,the negative cross stiffness is much larger than the main stiffness;the smaller the friction,the higher the rotor speed and the smaller the eccentricity of the locked position;floating ring seals locked with a smaller eccentricity can cause oil-whip unstable phenomena in accordance with engineering experience.