高低压转子弹性支承振动应力信号的LMD切片谱分析与时频分布

LMD Slice Spectrum Analysis and Time Frequency Distribution of Vibration Stress Signal of High and Low Pressure Rotor Elastic Support

针对传统的频谱分析方法不能很好地辨识航空发动机转子振动特征频率的问题,采用局部均值分解(Local Mean Decompo⁃sition,LMD),结合切片谱的频谱分析方法,对航空发动机转子振动信号进行自适应模态分解与峰值频率辨识;对转子振动信号进行时频分析,得到其时频分布。将该方法应用于某航空发动机高、低压转子的弹性支承振动应力信号分析中。结果表明:相比于发动机振动正常状态,在发动机振动异常状态下,高、低压转子弹性支承振动应力信号的LMD切片谱中除了存在高、低压转子的基频和倍频成分,还存在高、低压转子间的调制频率,且在异常状态下F分量的时变特征更加明显。采用LMD切片谱分析方法获取了发动机振动正常状态和异常状态下的振动频谱特征和时频分布,可为航空发动机转子振动特征提取与状态判别提供参考。

In order to solve the problem that the traditional spectrum analysis method can not identify the characteristic frequency of aeroengine rotor vibration well,the frequency analysis method of local mean decomposition combined with slice spectrum is used to decom⁃pose the vibration signal of aeroengine rotor adaptively and identify the peak frequency.The time-frequency distribution of rotor vibration signal is obtained through time-frequency analysis.The method is applied to the analysis of vibration stress signal of elastic support of high and low pressure rotors of an aeroengine.Compared with the normal state of engine vibration,in the LMD slice spectrum of vibration stress signal of elastic support of high and low pressure rotors under abnormal state of engine vibration,in addition to the fundamental frequency and multiple frequency components of high and low pressure rotors,there are also modulation frequencies between high and low pressure rotors,and the time-varying characteristics of F components under abnormal state are more obvious.Therefore,the vibration spectrum characteristics and time-frequency distribution under normal and abnormal state of engine vibration are obtained by this method,which can provide certain reference for vibration feature extraction and state identification of aeroengine rotor.