某型航空发动机中介主轴承早期微弱故障诊断研究

Research on the Early Weak Fault Diagnosis of Aero-engine Intershaft Bearing

针对基于机匣采集的振动信号难以有效提取出航空发动机中介主轴承早期微弱故障特征的问题,提出了基于巴特沃斯低通滤波器降噪和Hilbert包络解调的中介主轴承早期微弱故障诊断方法。该方法依托带涡轮支承和外机匣的新型航空发动机中介主轴承试验器,首先,开展某型发动机巡航状态下健康中介主轴承试验,获取基准振动频谱特征;然后,进行外圈剥落预置故障的轴承试验,对采集的振动信号通过低通滤波降噪并进行Hilbert包络分析解调出低频故障信号;最后,对比分析健康主轴承试验与轴承故障试验的时域波形、频谱和包络谱。结果表明,包络谱中转差信号与呈现“山”型边带特征,可用于诊断该型航空发动机中介主轴承外圈的早期剥落故障。

A new analysis method combined with least mean square(LMS)algorithm and Hilbert envelope demodulation was proposed to solve the problem of being difficult to extract the weak fault characteristics of aero engineer intershaft bearing,which is based on casing signal.Firstly,the impulse experiment was performed by the healthy intermediate bearing,the vibration signals of the outer casing was acquired and analyzed.Secondly,the experiment of the rolling bearing with the outer races failure was performed,the fault signal was extracted by low pass filtering and Hilbert envelope demodulation.Finally,frequency spectrum and envelope spectrum of the vibration signal by the failure rolling bearing were compared in detail with those of the vibration signals by the healthy intermediate bearing.The results demonstrated that the characteristics of the slip frequency combined with the convex shape side band feature could be used to diagnose the early spalling fault of the main bearing outer ring.