某双转子发动机冲击振动的分频小波提取与故障分析

采用小波-时频方法对某双转子发动机地面实测数据进行了分析,得到了试车过程中系统在不同工作状态下振动的时频特征。在振动能量的时频分布图中,不同的频率区间内含有不同的冲击成份;在此基础上对信号在不同的频带进行谐波小波包分解,分解信号能量主要集中在某一个频带范围内,进一步分析可以确定系统滚动轴承失效模式。 

Wavelet Extraction of Impact Vibration Frequency Component and Fault Analysis for a Twine Spool Aero-Engine

Noise and weak symptom give rise difficulties to aero-engine vibration monitoring and faults diagnosis.The conventional methods in time or spectrum domain are not so effective for it is hard to detect some kinds of fault symptoms.After measuring the data in an aero-engine on the ground,its time-frequency characteristics under different working conditions were analyzed.First,the signals were analyzed using Morlet wavelet and then the frequency component could be extracted from their time-frequency plane.Some impact components were obvious in the time frequency plane which indicated that some faults might occur in the rotor system.They were located in the band of bearing characteristic frequencies.Second,the signal was decomposed using harmonic wavelet whose resolving capability is high in both time and frequency domain in the bearing characteristic frequencies.Then the components of different frequencies were obtained by harmonic wavelet.Energy of the signal was concentrated in some frequency band.From these results of the harmonic wavelet analysis in the bearing characteristic frequencies,the kind of fault can be determined easily.