发动机非线性转子裂纹检测与延缓扩展的研究

Research of Crack Detection and Delay Crack Propagation on Engine's Nonlinear Rotor

发动机非线性转子裂纹的存在及扩展易引起重大安全事故,因此通过分析转子的振动信号检测裂纹是否存在和当裂纹存在的情况下如何延缓裂纹扩展显得尤为重要。非定常状态下裂纹转子的振动信号显现出非周期、非线性,并且裂纹故障特征易被其它过渡信号掩埋,检测的难点是如何从上述信号中提取故障特征,采用希尔伯特黄(HHT)边际谱方法可提取出裂纹故障特征。另外针对裂纹扩展问题,提出了一种新的可描述转子任意旋转位置时裂纹开闭程度模型,对不同转子参数所引起裂纹开闭程度的变化,提出了延缓裂纹扩展的策略。仿真结果表明,HHT边际谱可实现对4%程度转子裂纹的早期检测,并且提出的延缓裂纹扩展方法可有效的延缓转子裂纹扩展。

The existence and propagation of a crack on an engine＇s nonlinear rotor can cause serious accident easily, so it is quite important to detect rotor crack through analyzing rotor vibration signals and delay crack propagation when a crack exists. Cracked rotor＇s vibration signal is non - periodic and nonlinear under transient response, the crack fault characteristics can be easily buried with other transient signals, the difficuhy of detection is how to extract fault characteristics from signals. This paper proposes a HHT marginal spectrum method to realize the detection of crack fault characteristics. In addition, a novel model is proposed to describe the opening and closure of rotor at any rotating positions refer to the propagation of the crack and tactics of delaying crack propagation based on the effect on the opening and closure of the crack caused by the change of different rotor parameters. The simulation results show that the HHT marginal spectrum can realize the early detection of about four percentage depth of a crack, and the methods of delaying crack propagation can delay crack propagation effectively.