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.