Research On Online Health Diagnosis Technology For Turbofan Engines

Aero-engine health management technology can not only improve the security of engines, but also reduce maintenance cost, shorten maintenance cycle and increase engine efficiency. After several decades of development, aero-engine online health diagnosis technology which achieves real-time monitoring and fast fault locating has become an important tool of health management.The fault modes of turbofan engines are studied and the measurement parameters selection of fault diagnosis system is determined.Fault simulation is performed based on component-level model of a turbofan engine. Based on simulation results the similarity and linearity of fault modes are analyzed, which laid a foundation for gas-path fault diagnosis.Steady-state baseline modeling method for turbofan engines is studied. According to simulation data from engine component-level model in different flight states, the corrected parameter formulae are determined. The base values of baseline model are obtained by cubic fitting. The mothed of baseline correction is studied by taking the influence of on-and-off of the bleed vavle as an example. Finally steady-state baseline model is established. Gas-path diagnosis algorithms based on steady-state baseline model are designed, which include weighted least-squres method and primary factor model method. The modified weighted least-squres is proposed to improve the precision of the diagnosis. Digital simulation results show the effectiveness of the algorithms.According to the functional requirement of engine online diagnosis system, the overall scheme of online diagnosis system is proposed. And the system architecture is divided using structured design. Data preprocessing and validity checking algorithms are designed. The engine online health diagnosis simulation system is established.