Dynamic Characteristics Analysis of Flexible Rotor System With Pedestal Looseness

Abstract

Due to the limitation of assembly conditions and working load environment, the design of pedestal looseness is often used in the structural design of aeroengine multi support flexible rotor, which affects the vibration response and stability of the rotor system. In this paper, a dynamic model of a flexible rotor system with pedestal looseness is established for a practical aeroengine flexible rotor system. Next, a nonlinear modal analysis process for the multi degree of freedom nonlinear rotor system is proposed. Based on this, the nonlinear modal characteristics of the flexible rotor system with pedestal looseness are analyzed. An interval prediction method of modal damping interval for stability analysis of rotor system is presented, and the influence of key characteristic parameters on modal damping and vibration stability of rotor system is explored. Finally, the vibration characteristics of the rotor system are obtained by numerical integration method. The results show that the modal characteristics of the rotor vary with the amplitude of the rotor, and have the feature of interval distribution; vibration stability mainly depends on tangential friction and additional lateral constraint; when the amplitude of the rotor is large, the backward whirling motion may occur and the vibration may be unstable. This paper will provide a theoretical method for dynamic optimization of multi support flexible rotor system, which is helpful to ensure the reliability and safety design of aeroengine.