密封-转子系统气流激振问题数值仿真

对于密封中发生气流激振的故障诊断问题,基于有限元方法,应用Muzynska非线性密封力模型建立了密封-转子系统动力学模型,通过数值积分方法研究了升/降速过程的气流激振失稳规律和振动特性,并分析了在变速和稳速情况下偏心量的影响。结果表明:气流激振力会使系统固有频率升高,使发生共振时的振幅降低;发生气流激振会出现锁频现象并伴有组合频率特征;降速时由于气体的流动性强从而导致切向惯性力很弱,惯性效应不明显;当偏心量较小时频谱上只出现了锁频,随着偏心增大组合频率出现并不断丰富;稳速时气流激振频率随偏心的提高而增大,并出现了频率突变。 

Numerical simulation on seal-rotor system with airflow induced vibration

For the diagnosis of airflow induced vibration fault in the seal, the dynamic model of seal-rotor system was established based on finite element method and Muzynska seal fluid force model. The airflow induced vibration instability law and dynamic characteristics from run-up and run-down processes were studied by numerical simulation method. And the different eccentricities'' effects during the case of variable speed and steady speed were also analyzed. The result showed that natural frequency of rotor system was increased by the airflow excitation force, and the amplitude was reduced in resonance zone. The frequency locking phenomenon and combination frequency characteristics appeared by airflow vibration with the speed increase. The phenomenon of hysteresis under run-down conditions was not obvious because of the strong gas flow. Only frequency locking occurred when the eccentricity was small, the combined frequency was observed and enriched with eccentricity increase. The airflow vibration frequency was enhanced and changed suddenly by increasing eccentricity in the process of constant rotating speed.