摘要
基于Jeffcott转子模型,用6自由度方法研究考虑涡轮非线性流固耦合力的转子径向碰摩动力学特性。通过响应分叉图、波形图、频谱图、轨迹、Poincaré图以及频率瀑布图分析在涡轮非线性流固耦合力作用下转子径向碰摩的动力学表现。与不考虑涡轮非线性流固耦合力相比,转子的径向碰摩的稳定运动区大大减小,转子的碰摩转速门槛值也相应降低,并且碰摩一开始系统振动就出现比较复杂的运动形式;轴向振动的频谱中明显出现了密集的超谐波群,扭转振动的频谱中则明显出现了密集的亚谐波群,这种具有混沌特征的频率成分代表了系统在碰摩力和涡轮非线性流固耦合力作用下的主要运动形式:在整个转速范围内,横向振动几乎具有单一的同步频率成分,轴向振动则表现出非常丰富的超谐波频率成分,这些频率成分主要分布于三个随转速的增加分别向三个固定的频率逼近且幅值逐渐升高的密集超谐波频带,扭转振动则在1/2倍频附近表现出丰富的亚谐波频率成分,其幅值也随转速的增加而逐渐升高。上述结论对涡轮转子系统的动力学设计和故障诊断具有重要意义。
Based on a Jeffcott rotor model, dynamic characteristics of rotor＇s radial rub-impact with the consideration of turborotor＇s nonlinear fluid-structure interaction forces are studied in six degrees of freedom of the rotor. Dynamic behaviors of the system are analyzed with bifurcation diagrams, waveforms, frequency spectrums, orbits, Poincaré maps and waterfalls. It is concluded that the stable range of the system responses is largely reduced, the rotating speed threshold of rub-impacting is decreased, and the complicated motion patterns appear at the early stage of rub-impact, compared with the case without considering turborotor＇s nonlinear fluid-structure interaction forces; thick superharmonics and subharmonics emerge in the axial and torsional vibration spectrums respectively, and these components characterizing chaotic motion are the main motion patterns of the system; in the full range of rotating speed, lateral vibrations almost take on pure synchronous component, the axial vibration demonstrates rich superharmonics, which mainly scatter in three thick superharmonic bands that approach to three fixed frequencies with their amplitudes growing up as rotating speed increases, the torsional vibration displays rich subharmonics near 1/2 time frequency component, the amplitudes of which increase with rotating speed. These conclusions are of great significance to the rotordynamic design and fault diagnostics of turborotor systems.
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2008年第6期199-205,共7页
Journal of Mechanical Engineering
基金
国家杰出青年科学基金(50425516)
关键词
非线性流固耦合
转子动力学
动力学分析
径向碰摩
全自由度
涡轮
Nonlinear fluid-structure interaction Rotordynamics Dynamic analysis Radial rub-impact Full degrees of freedom Turborotor
