Research On Fault Diagnosis Method Of Turbofan Engine Startup

Startup is the first stage of the turbofan engine working process. Safe and reliable startup ensuresthat the engine can smoothly enter the normal working condition. Therefore, it is of great practicalimportance to build the turbofan engine’s startup model and to study fault diagnosis techniche of thestartup process.The characteristics of turbofan engine startup process were studied and main factors thatinfluence the startup performance were analyzed. Without losing accuracy of convergence andincreasing the number of iterations, by using the method of obtaining the optimal residual of theinterative process, iterative algorithm for the present dynamic model has been improved to enhancesthe model calculation convergence. The characteristics of the rotary component of engine at lowspeeds were obtained by using the exponential extrapolation method and the component-level groundstartup model was built. The dynamic modeling method for air restart was studied on the basis of thecomponent-level ground startup model. The initial guess values selection problem of air restart atinitial point was avoided through the simulation of speed-down process after flameout. The dynamicsimulation of the whole process of the engine’s speed-down and air restart after flameout wasachieved. Simulations of startup on the ground and in the air show that the model has a fasterconvergence and good precision.The typical fault symptoms, characteristics and causes in startup process were analyzed, and theeffects of adjustable parameters on the engine’s performance were discussed. Simulation of typicalstartup failure was performed and the model of failures in engine’s startup process was built on thebasis of the component-level ground startup model to simulate typical startup failures. By means ofcomparing normal startup data with former data and considering experts’ experience, a practicalmethod to diagnose failures in unsuccessful startup was proposed, and the validity of diagnosisalgorithm has been verified according to the test data and data obtained from the engine model.