Investigation on nonlinear lateral-torsional coupled vibration of a rotor system with substantial unbalance

作     者：Jie HONG Pingchao YU Yanhong MA Dayi ZHANG Jie HONG;Pingchao YU;Yanhong MA;Dayi ZHANG

作者机构：School of Energy and Power EngineeringBeihang UniversityBeijing 100083China Collaborative Innovation Center of Advanced Aero-EngineBeihang UniversityBeijing 100083China Beijing Key Laboratory of Aero-Engine Structure and StrengthBeijing 100083China 

出 版 物：《Chinese Journal of Aeronautics》 (中国航空学报（英文版）)

年 卷 期：2020年第33卷第6期

页      面：1642-1660页

核心收录：

学科分类：08[工学] 082502[工学-航空宇航推进理论与工程] 0802[工学-机械工程] 0825[工学-航空宇航科学与技术] 0801[工学-力学（可授工学、理学学位）] 

基　　金：the support from the National Natural Science Foundation of China(Nos.11772022,51575022 and 51475021) the support by the Academic Excellence Foundation of BUAA for Ph.D.Students。 

主　　题：Instability Lateral-torsional coupled vibration Lock-in phenomenon Modes Unbalanced rotor 

摘      要：Substantial unbalance may be caused by fan blade off during the operation period of gas turbine engines,and related dynamic problems are very critical to the safety design of rotor system in aero-engine.This article aims to understand lateral-torsional coupled vibration of the rotor system with substantial unbalance.The governing equation of a modified unbalanced rotor system is established based on Lagrangian approach.Then,a mathematical analytical method is proposed in which a linear approximation is derived and the Floquet theory and Hill’s method are incorporated,from which the modal characteristics of the unbalanced rotor are obtained.The modal characteristics of the unbalanced rotor system are revealed comprehensively for the first time.Furthermore,the relation between the modes and responses of the unbalanced rotor is discussed in detail.The results show that the lateral vibration and torsional vibration of the unbalanced rotor are coupled through the inertial terms in the governing equations.Due to the coupling,veering and lock-in phenomena occur between the frequencies of the forward whirl mode and the torsional mode.Furthermore,lock-in can lead to a kind of principal instability.With regard to the response of the unbalanced rotor,both natural vibration components and enforced vibration components appear in the lateral response,while only natural vibration components appear during torsional vibration.Moreover,natural vibration components play a crucial role in the response within the principal instability region and cause divergence of the vibration amplitudes in the lateral and torsional directions.