Nonlinear vibrations of a dual-rotor-bearing-coupling misalignment system with blade-casing rubbing

Abstract In order to reveal the nonlinear vibration characteristics of an actual dual-rotor-aero-engine with blade-casing rubbing, a dual-rotor-bearing-coupling misalignment system with blade-casing rubbing are investigated based on numerical simulation and experimental measurement in this paper. A dual-rotor experimental rig is designed and manufactured, that is a simplified structure according a dual-rotor-aero-engine. The dynamic model of the dual- rotor-bearing system of the test rig is established based on the finite element method (FEM) taking into account the coupling misalignment, blade-casing rubbing and the nonlinearities of all of the supporting rolling element bearings. The component mode synthesis (CMS) method is applied to the model order reduction of the high-degrees of freedom (DOFs) dynamic model. The numerical and experimental nonlinear vibration responses of the dual-rotor system are compared with each other at different rotational speeds at different rotational speed ratios. The numerical results are in agreement with the experiment. These results reveal the nonlinear vibration characteristics of the dual-rotor-bearing-coupling misalignment system with local blade-casing rubbing fault.