Adaptive Life Extending Control of Aircraft Engine

Abstract

Current Life Extending Control (LEC) aims to extend engine life with minimum sacrifice in performance. However, it does not take the engine-performance degradation into account. When engine-performance degrades, its acceleration performance reduces. Keeping on using the current LEC designed for no-degradation engine may extend the engine life with substantial sacrifice in performance, and then make the engine not meet the normal needs when the engine degrades. In order to solve the problem, this paper analyzes the effect of current LEC on the engine acceleration and the life of selected engine component firstly. On this basis, the adaptive life extending control of aircraft engine is proposed. It could adjust the LEC law according to the engine-performance degradation. Moreover, the adaptive LEC system structure is built, which could evaluate engine-performance degradation in real time and provide proper LEC law for various engine-performance degradations through interpolation. The simulation results show that adaptive life extending control system could choose appropriate LEC limit line according to current engine-performance status, which could extend component life and maintain the engine acceleration performance in the whole life. Nomenclature N l =Fan speed N l Design ， =Fan speed at design point 41,max T =Highest temperature of turbine inlet max T  =Maximum temperature difference before and after the high-pressure turbine vane   t =Total strain ' N f =Thermo-Mechanical Fatigue (TMF) life of the high-pressure turbine vane T stable =Settling time of low-pressure rotor T rise =Rise time of low-pressure rotor I. Instructionn recent years, with the upgrading of aircraft engine electronic controller, intelligent control was incorporated into the study of aircraft engine control systems, where life extending control was one of them [1,2] . Lorenzo et al. first introduced LEC in the early 1990s [3][4][5] , which was applied to the Space Shuttle Main Engine (SSME).Guo Ten-huei elaborated several common LEC methods of the aircraft engine, and described the basic structure and key technologies of LEC [6,7] . Then NASA Glenn Research Center used the Thermo-Mechanical Fatigue (TMF) of a critical component to demonstrate how a LEC can drastically reduce the engine life usage with minimum sacrifice in performance. Simulation results showed that LEC could ensure that the engine basic I Downloaded by KUNGLIGA TEKNISKA HOGSKOLEN KTH on August 11, 2015 | http://arc.aiaa.org |