Dynamic modelling and stability analysis of aero-engine rotor system considering aerodynamics

Abstract

Bolting joint is widely used in aero-engine, but the existing analysis theory of bolting joint interface strength connection completely ignores the aerodynamic load borne by blade and support disks. Therefore, in view of the aero-engine rotor system, we establish a bolt-flange connection blade-disk-drum joint model. Based on the l-stubs strength theory, considering three failure modes of bolt-flange interface stiffness, we study the connection strength of the disk-drum structure under aerodynamic force and bolt preload, and analyse the steady-state response of the rotor system under different connection states. The results show that the aerodynamic load will produce three kinds of yield phenomena on the rotor interface, and reduce the critical speed of the rotor system. Due to the stiffness loss of the connection interface, the critical speed of the rotor decreases and a subcritical resonance phenomenon occurs after the second critical speed. At the same time, the increase of interface contact damping results in the failure of vibration energy transfer between disk and drum, which makes the drum more susceptible to external excitation. By balancing bolt preload and interface friction coefficient, the influence of aerodynamic load on interface contact characteristics can be reduced, and the working efficiency of rotor system can be improved.