针对航空发动机叶片碰摩故障难以实现在线监测的问题,展开基于静电感应原理的碰摩故障监测新方法研究。分析了碰摩颗粒产生与荷电机理,以静电传感器理论和点电荷感应信号特征为依据,建立了周期碰摩静电感应理论模型。研究结果表明:周期碰摩在静电传感器上的输出是一系列以碰摩频率为间隔的随频率增大幅值迅速衰减的周期离散谱线。为了验证模型的正确性,利用自行研制的静电传感器,采用模拟碰摩的方式进行了两组实验。第1组实验结果表明传感器可以监测到模拟碰摩故障产生的带电颗粒,碰摩阶段的信号活动率水平明显增大,但事件率没有出现明显的变化;第2组实验在信号频域出现了非常明显的特征频率及其二倍频,且二倍幅值频随频率增大迅速衰减,证明了模型的有效性。
A new method for rub fault detection based on electrostatic technique is discussed for online monitoring of blade rub in aeroengine.The generation process and charging mechanism of blade rub debris are first analyzed,and then the electrostatic probe theory and characteristics of electrostatic induction of a point charge are presented.After that a periodical rub detection model is established.The model shows that a series of characteristic frequencies which decay greatly over frequency will appear in the sensor output signal when periodical rub occurs.Two simulated rub experiments are performed with an electrostatic sensor.The result of the first experiment shows that rub debris could be detected by the sensor,while the activity level(AL) significantly increases and the event rate(ER) does not change during the rub.The second experiment shows that the characteristic frequency and its double frequency in the signal and the amplitude decay greatly over frequency.Thus,the validity of the periodical rub detection model is proved.