Effect of Rolling Bearing on Dynamic Characteristics of Seal-Rotor System

Abstract

For problem which the vibration of rolling bearing-rotor system in the aero-engine with sealing device, the dynamic model of sealing-rotor system supported by angular contact ball bearings was established based on the finite element theory, Muzynska seal force model and rolling bearing force model. Vibration response characteristics of the system were obtained by the method of Newmark-β numerical integration. The results show that the phenomenon of frequency locking occurs in the rotor system after airflow excitation, accompanied by the characteristics of combination frequencies; when the bearing clearance is larger, the unstable vibration caused by the larger bearing clearance can be restrained to some extent by the airflow excitation force at lower rotating speed. The chaotic characteristics of the bearing end are gradually strengthened by the influence of the airflow excitation. In the absence of airflow force, the amplitude of rotor is increased by enhancing the bearing clearance and contact angle, and the amplitude is reduced by raising balls number properly. In the presence of airflow force, the number of balls, bearing clearance and contact angle have a little effect on the amplitude due to the influence of airflow excitation. Therefore, the factors such as bearing skidding and axial load are considered, in order to reduce vibration, it is necessary to properly improve the processing accuracy of the rotating shaft in the bearing installation and select the bearing type with smaller contact angle. The results provide a theoretical basis for fault diagnosis with airflow excited vibration and rolling bearings selection of this kind of rotating machinery.