Dynamic characteristic analysis of rotor-blade-casing system with rub-impact fault

Taking a rotor-blade-casing coupling system as the research object, finite element model of the rotor-blade-casing coupling system was established by ANSYS software, and then the validity of the model was verified by the natural frequencies obtained from experimental measurement. A point-point contact element was used to simulate the fixed-position rubbing fault between the blade and the casing, and further the validity and feasibility of the method adopted were also verified by the testing response data. Finally, the influences of different penetrations at a certain rotate speed, the constant penetration at different rotate speeds and the constant clearance at different rotate speeds on system vibration responses were analyzed. The results show that rubbing on the tip of blade mainly excites high multiple frequency components, and the amplitude of the multiple frequencies near the pitching rigid model increases. Under the constant penetration at different rotating speeds, the frequency components of the system is reduced at high speed rubbing conditions, and the normal rubbing force also changes with the increase of rotating speed. Under the constant clearance at different rotating speeds, the amplitudes of some multiple-frequency components are greater than those of rotating frequency when the rubbing appears at high speed, and repeatedly collision rebound can be observed during continuous rubbing.