涡轴发动机尾气静电监测信号影响因素分析

 针对某型航空涡轴发动机试车台实验所获得的尾气静电监测信号,结合发动机台架试车状态和性能数据,分别在两个时间尺度上展开分析研究。研究发现发动机的工作状态和健康状态均对尾气静电信号产生重要影响。在小时间尺度上的分析发现,无故障情况下影响尾气静电信号变化的主要因素为燃油供给量,尾气静电信号能量随燃油供给量的增加近似按指数规律上升;而在大时间尺度上的分析发现,在一定的燃油供给和恒定的自由涡轮转速条件下,尾气静电信号能量随着发动机性能的缓慢衰退而逐渐上升。实测尾气静电信号所反映的趋势与初步的理论分析结果相一致,为建立涡轴发动机尾气静电信号的健康"基线",进而用于气路状态监测及故障识别提供了初步的依据。研究还发现,静电监测技术不仅能够为突发性故障提供预警信息,而且能够反映发动机整机性能衰退,进一步拓展了静电传感器的监测能力及其在航空发动机健康管理中的应用。

Analysis of Factors Influencing the Exhaust Gas Electrostatic Monitoring Signals of a Turbo-shaft Engine

Based on the exhaust gas electrostatic monitoring signals of a turbo-shaft engine,an analytical study is carried out in combination with other engine operating parameters on two time scales.The results presented in this study show that both the engine operating condition and health status have a significant effect on the monitored exhaust gas electrostatic signal.On the small time scale,for an engine without fault the major factor that may cause change in the electrostatic signal is fuel delivery,and the energy of the signal will increase almost exponentially with more fuel feed.On the large time scale,given a constant fuel delivery and power shaft speed,the energy of the exhaust gas electrostatic signal will increase as the engine deteriorates gradually.The trend extracted from the monitored signal is in agreement with the theoretical analysis,which may serve as an initial basis for the establishment of a base line in the electrostatic signal,and in turn facilitate further application,such as to gas path component condition monitoring and fault identification.The research also demonstrates that the electrostatic monitoring technique can not only provide a precursor for the impending fault,but also track the gradual performance degradation for a turbo-shaft engine,and this may mean an extension of the capacity and application of the electrostatic monitoring sensor in engine health management.