Advanced Fighter Aircraft Sub-Systems Optimal Synthesis/Design and Operation: Airframe Integration Using a Thermoeconomic Approach

Abstract

A decomposition methodology based on the concept of “thermoeconomic isolation” and applied to the synthesis/design and operational optimization of an advanced tactical fighter aircraft is presented in this paper. Conceptual, time, and physical decomposition are used. The physical decomposition strategy employed, called Iterative Local-Global Optimization (ILGO), was developed by Munoz and von Spakovsky and has been applied to a number of complex stationary and transportation applications. This decomposition strategy is the first to successfully closely approach the theoretical condition of “thermoeconomic isolation” when applied to highly complex, highly dynamic, non-linear systems. The total system is decomposed into eight sub-systems, five of which have degrees of freedom (a total of 493). These five are the airframe sub-system (AFS), the propulsion sub-system (PS), the environmental control sub-system (ECS), the fuel loop subsystem (FLS), and the vapor compression and PAO loops subsystem (VC/PAOS). The three without degrees of freedom are the equipment group (EGS), the permanent payload (PPS) and the expendable payload (EPS). For the ones with degrees of freedom, detailed aerodynamic, geometric, thermodynamic, and physical models at both design and off-design were formulated and implemented. The highly complex problem of integrating the synthesis/design of the airframe sub-system with the PS and the thermal driven sub-systems (ECS, FLS, and VC/PAOS) is solved using the novel decomposition approach mentioned above. The most promising set of aircraft sub-system configurations based on both aerodynamic performance and energy integration analysis are evaluated for all mission stages including the transients segments. The optimal configuration (synthesis) and geometry (design) of the airframe sub-system is determined simultaneously with that for the total aircraft system, i.e. with that for all of the other sub-systems. Results for this system and its sub-systems are presented below.