Abstract: According to the working principle and composition of aircraft engine, as well as the similar thermal equations of each module, equal flow between engine modules and rotor power balance, the relationship mathematical model of performance parameters between engine and components is established by applying small deviation theory.Through performance separation, the model only represents the change of module performance parameters when faults occur, without the change of performance parameters when each module is re-matched after faults. Finally,the variation of engine performance parameters is calculated by collecting the decay of module performance parameters in aero-engine finger print. The model effectiveness is verified by comparing with the changes of acquired engine performance parameters. The impact of engine module performance changes on the performance of whole engine is confirmed by the current model, providing theoretical reference for engine fault diagnoses and troubleshooting.

Key words: areo-engine, module performance, thermal process, small deviation theory, mathematical model