Compressor exit temperature analysis, part III

摘要

The third in a series of investigations has been conducted on the impact of the aircraft mission in selecting an optimum engine cycle, with focus on compressor exit temperature. A strike fighter mission characterized as a "high-low-low-high" mission, in reference to its altitude segments, provided the mission constraints. The previous studies addressed Mach 3 interceptor and air superiority fighter missions. This study was repeated for a typical strike fighter mission because of the current interest in the Joint Advanced Strike Technology (JAST) Program. An augmented turbofan engine model incorporating state-of-the-art turbine engine technology was used to optimized overall compression system pressure ratio (and thus, compressor exit temperature), turbine rotor inlet temperature, and bypass ratio. Plots of uninstalled engine performance data showed that there was no clear optimum cycle, indicating the need for the application of mission constraints. Installed engine analysis and aircraft sizing were then performed under the mission constraints to determine the optimum cycle, with the figure of merit being takeoff gross weight. A simple cost comparison was then performed to illustrate engine/aircraft system acquisition cost benefits resulting from a higher performance, more costly engine that enables a lighter takeoff gross weight aircraft.