转速比对双转子系统非线性动力学特性影响

Influence of Speed Ratio on Nonlinear Dynamic Characteristics for Dual Rotor System

以航空发动机双转子系统为研究对象,考虑挤压油膜阻尼器以及中介轴承的非线性力,通过有限元法和固定界面模态综合法建立了双转子系统的耦合动力学模型。利用仿真计算分析了转速比对转子系统非线性响应特性的影响。研究表明:响应中能观察到较明显的交叉激振现象;响应中除了内外转子的不平衡激励频率之外,还出现了两者的组合频率,但不同转速比情况下的组合频率不同;同向旋转情况下的临界转速均不小于反向旋转;转速比对转子系统的轴心轨迹和运动的周期性有较大影响。最后,通过试验验证了本文建模和仿真结果的正确性。

Nonlinear dynamic model of a coaxial rotor system is established by combining the finite element method and the fixed interface modal synthesis method with nonlinear forces of squeeze film damper and intermediate bearing considered.Nonlinear dynamic characteristics of the co-and counter-rotating coaxial rotor system with different rotational speed ratios are studied and compared in the work.Results show that the unbalance excitation frequencies are dominant in the responses of the rotor system.Due to coupling effect of the intermediate bearing,some combinations of the unbalance excitation frequencies are also observed in the spectrogram while the combinations are different for co-and counter-rotating cases.Also,it is found that the critical speeds of the co-rotating system are equal or slightly higher than those of the counter-rotating case.The orbit and periodicity of the rotor system can be quite different for different speed ratios.Finally,the nonlinear model is validated by comparing the simulation results with the experimental data.