Dynamic model and theoretical investigation for the fan-blade out event in the flexible rotor system of aero-engine

The fan-blade out (FBO) from a turbofan rotor is a real possibility during the complex operation cycling of an aero-engine. This paper aims to understand the dynamic behavior of the aero-engine rotor system with the FBO event by theoretical approaches and numerical simulations. The physical process of the FBO and its effects on the rotor system are analyzed first, from which the main mechanical characteristics on different time scales are acquired. Then a timeliness dynamical model considering the whole process of FBO event is put forward based on the structural and mechanical characteristics of rotor. Moreover, some simulations for the flexible rotor in aero-engine with FBO are carried out and vibration characteristics are achieved. The dynamic response of FBO rotor is driven by a combination of typical mechanical processes. The results reveal that the sudden unbalance will increase the transient response and excite modal vibration of the rotor system. The asymmetry of inertia and the deceleration will introduce the parametric excitations into the rotor system. The blade-casing rubbing can increase the resonance speed of the rotor and cause the abundant frequency components, while the vibration amplitude and reaction force of the transient response are decreased. For the practical rotor system in aero-engine, this research can provide some theoretical guidance for the safety design.