某航空发动机压气机叶-盘耦合振动分析

基于循环对称结构模态分析基本理论,建立并验证压气机叶-盘结构耦合振动特性分析方法和流程。在能够线性求解的前提下,考虑叶-盘间实际连接情况,不忽略叶片榫头与轮盘榫槽间应力状态对振动特性的影响。选取某民航发动机高压压气机第三级叶-盘结构为分析对象,提取结构特征参数,在ANSYS软件中建立起叶-盘结构的三维有限元模型,并进行耦合振动仿真分析。首先计算该叶-盘结构在不旋转工况下的频率和振型,然后计算其在常用转速工况下存在预应力时的频率和振型,分析得到离心载荷对频率和振型的影响规律。最后分析其行波振动特性,计算3节径1,3,5阶行波节径振动频率。考虑外缘叶片受到周期性气体力对叶-盘的激振影响,画出共振特性曲线,为后续结构分析和排故提供依据,同时也为压气机叶-盘结构的振动特性分析提供了便于工程应用的方法。

Coupled Vibration Analysis of Compressor Blade-disc Structure from an Aero Engine

Based on modal analysis theory of cyclic symmetric structure, the vibration characteristics analysis method of compressor blade-disc structure had been established and verified. Under the premise of linear solution, considering the actual connection between blade and disc, the influence of stress between blade root and disc groove on the vibration characteristics is not neglected in the method. A third stage blade-disc structure from a civil aero-engine high pressure compressor was selected as analysis object, after extracting the structural geometry parameters, a three-dimensional finite element model of blade-disk structure was established on ANSYS software platform, and the coupled vibration simulation analysis was carried out. First, the natural frequencies and mode shapes of blade-disc structure was calculated; and then, the frequencies and mode shapes of blade-disc structure under impact of pre-stress by rotating on common speeds was calculated; also the influence of centrifugal load on frequency and mode was analyzed. Finally, traveling-wave vibration characteristics of the blade-disc structure was analyzed, the traveling-wave frequencies of 1, 3, 5 order vibration from 3-nodal diameter mode was calculated. The excitation on blade-disc structure by periodic air force in duct was considered, and the Campbell curve was figured out. It provided a necessary numerical basis for subsequent structural analysis and vibration troubleshooting, and an easy method for engineering application of compressor blade-disc structure vibration characteristics analysis.