航空发动机整机有限元模型转子动力学分析

现代航空发动机在工作中不断变化的机械激振,气动激振频率越来越复杂,这使得对航空发动机振动分析必须考虑各结构间的动力影响.因此,利用能够考虑陀螺力矩影响,基于NASTRAN中实体单元编制的转子动力特性计算程序,对发动机整机进行了动力特性计算.首先对转子支承结构传递函数(动刚度)进行计算,并进一步研究其对转子动力特性的影响;分析比较基于不同单元模型计算时,盘轴耦合振动及盘轴连接处的角刚度对转子动力特性的影响,证明了基于实体单元的整机模型能够准确考虑各种振动模态.最后,在分析中发现了高阶转子弯曲振动模态与机匣振动耦合现象及其变化规律,在计算分析的基础上研究了在考虑机匣振动耦合时转子系统临界转速的确定方法.

Rotordynamic analysis of whole aero-engine models based on finite element method

In modern times,the mechanical and aero forced frequency on aero-engines become more and more intricate,so dynamical interaction of different structures should be taken into account in aero-engine vibration analysis.For above reasons,a rotordynamic analysis of a whole engine model based on three-dimensional solid element was performed using the program which could take gyroscopic moment into account on NASTRAN.An unbalance response calculation of the casing was performed to predict the transfer function(dynamic stiffness) at the bearing support,as well as their effects on rotordynamics.In the analysis of models based on different elements,the effect of corner stiffness between shafts and disks was compared,as well as the coupled vibration of disks and shafts,it is proved that various vibration modes could be accurately calculated using the whole engine model based on solid element.A phenomenon of the coupled rotor bending and casing vibration was captured,as well as the effect rule,it was showed the third rotor critical speed of the coupled rotor bending and casing vibration mode was a frequency range.The method to predict critical speeds and mode shapes of the rotor considering dynamic interaction between the rotor and casing was investigated.