A Feasibility Study of Life-Extending Controls for Aircraft Turbine Engines Using a Generic Air Force Model

Abstract

Turbine engine controllers are typically designed and operated to meet required or desired performance criterion within stability margins, while maximizing fuel efficiency. The U.S. Air Force turbine engine research program is seeking to incorporate sustainable cost reduction into this approach, by considering a life-cycle design objective if the life of the engine is considered as an objective during the design of the engine controller. Specifically during aircraft takeoff, the turbine engines are subject to high temperature variations that aggravate the stress of the material used in their construction and thus a negative effect in their life spans. Therefore, the control strategy needs to be re-evaluated to include operating cost, and extending the life of the engine is one way to reduce that. Life-Extending Control (LEC) is an area that deals with control action, engine component life usage, and designing an intelligent control algorithm embedded in the FADEC. This paper evaluates the LEC, based on critical components research, to demonstrate how an intelligent engine control algorithm can drastically reduce the engine life usage, with minimum sacrifice in performance. Finally, a generic turbine engine is extensively simulated using a sophisticated non-linear model of the turbine engine. The paper concludes that LEC is worth consideration and further research should include development of the damage models for turbine engines, and experimental research that could correlate the damage models to actual damage for turbine engines. This could lead to implementation of online damage models in real-time that will allow for more robust damage prevention.