In combination with the problems of rotor cavity filled with oil vibration encountered in the test of aero engine rotor in the project

the research was carried out from the theory of vibration

dynamic characteristics and vibration signal analysis

and the failure mechanism of rotor disk cavity filled with oil was analyzed. The characteristics and regularity of instability vibration were acquired

the process and criteria for disc cavity fluid accumulation fault identification as well as its vibration monitoring guidance were established. The result showed that the subharmonic vibration was produced when the rotor speed was above the critical speed of the rotor if the rotor cavity was filled with oil

which caused the self-excited vibration of the rotor; and the frequency of the self-excited vibration was close to the first order critical speed of the rotor; and the rotor frequency vibration was still dominant when the rotor speed was below the critical speed

and the oil deposit could cause the increasing peak value of the over critical speed; the above-mentioned fault identification process and criteria were applied to an rotor of an engine to accurately identify the characteristics of rotor cavity filled with oil. Oil was found in the fan's secondary disk cavity when the rotor was dismantled. After cleaning up the oil

the abnormal vibration disappeared

which verified the correctness of the conclusions.