考虑性能退化的航空发动机故障诊断量化评估

Fault diagnosis during the entire life cycle of aero-engines has always been a hot research topic. In order to ensure the reliability of the aero-engine fault diagnosis algorithm under the condition of performance degradation，it is of great significance to quantitatively evaluate the fault diagnosability of aero-engines considering the performance degradation. Decouple the sliding window model of degraded areo-engine from two aspects：the measurability of the state quantity and the design of optimal state observer. The diagnosability is evaluated from two perspectives：detectability and isolability，then introducing Bhattacharyya distance as quantitative standard，and converting quantitative evaluation of fault diagnosability to calculation of multivariate distribution probability distance. Fault isolability is defined from the perspective of the fault space，the influence of the reference failure mode is stripped away，the isolability is transformed into the inherent attribute of the failure mode in the fault space，and the criterion for the detectability and isolability of aero-engine fault is provided. The simulation proves that the method proposed in this paper can perform diagnosability quantitative evaluation of the control system sensor，actuator failure and engine gas circuit component failure under the premise of aero-engine performance degradation.