转子密封系统流体激振问题的流固耦合数值研究

NUMERICAL SIMULATION OF FLUID-INDUCED VIBRATION IN SEALS BY FLUID-STRUCTURE COUPLING METHOD

随着叶轮机械的工作转速越来越高,工程中发生了大量的密封流体激振问题。实验证明,高转速下的流体激振属于自激振动,但采用传统的刚度阻尼线形假设无法模拟出这一物理现象。本文发展了一种高精度的流固耦合计算方法,用这种算法成功地模拟出转子密封系统在高转速下的自激振动,且捕捉到频率锁定的现象,而且发现随着转速的提高,固有频率也增大。另外,本文还得到了压比、预旋度对密封转子自激振动的影响规律。

Fluid-induced vibration of seals happened more and more frequently with the increasing of turbomachinery's rotational speed. Experiments verified that the fluid induced vibration is a kind of self-induced vibration. However, this phenomenon can't be caught by the custom linear stiffness-damping method. A high accuracy fluid-structure coupling numerical method is developed in the paper. The seal's fluid-induced vibration is studied by the present method. The self-induced vibration of seals at high rotational speed is caught successfully from the simulation, as well as the 'lock-in' phenomenon of the frequency. The numerical results also show that the amplitude of the natural frequency will increase with the rotational speed. Moreover, the influence of the pressure ration and the pre-swirling on the fluid-induced vibration is also studied.