Study of gas path analysis method for aero-engine based on functions of health parameters

A method for diagnosing the degradation of jet engines is presented. Aiming at the actual working condition of the engine, the assumption of functions of health parameters and the Multiple Operating Points Analysis based on Functions of health parameters (F-MOPA) is proposed for the first time in this paper. The assumption of functions of health parameters replaces the traditional method's assumption that the health parameters remain unchanged. In this new method, a mapping relationship is established between the health parameters and the engine’s working condition, which is more in line with the actual situation. The paper proposes the use of Taylor polynomials to approximate this unknown mapping relationship to capture the nonlinear information of the engine. The paper also investigates the effects of redundant measurement parameters, operating point intervals, and the number of operating points on the estimation of health parameters. The validation results show that F-MOPA meets the convergence accuracy when the Taylor polynomial is expanded to the second order. Increasing the number of sensors and operating points can improve the parameter estimation results and reduce the effect of the operating point interval on the calculation results. The F-MOPA method is more applicable as it converges better in smaller operating point intervals. Meanwhile, the F-MOPA method has an acceptable convergence of the algorithm.