Research on natural vibration responses based on asymmetrical dual-rotor model

The asymmetrical dual-rotor can represent special fault cases of an aero-engine, such as cracked rotors or lost blades, and to understand characteristics of natural vibrations of the system are very important on the design or maintenance stages of the aero-engine. The novel asymmetrical dualrotor model is put forward based on special fault cases of the aero-engine. In the coupled dynamics model, equations of motion and natural vibration are derived by using Lagrange's equation and the harmonic balance algorithm, systematically. Natural vibration frequencies are studied by using equations of natural vibrations of the model, and coupled natural vibration frequencies between rotors are investigated too. Response curves of coupled phenomena of the model are analyzed in detail. Due to effects of an asymmetry and coupling actions between rotors, complex natural vibration phenomena, such as three unstable regions and two super harmonic resonances on the low pressure (LP) rotor, are firstly investigated on the proposed novel dualrotor model. In addition, solutions of theoretical analyses are good consistent with results of numerical simulations, and results of experiments can further illustrate natural vibration characteristics of the dynamics model. Research results prove the correctness of the proposed coupled dynamics model.