Daniel Henric Rosell, Fluid Dynamics

The requirements of military aircraft are becoming increasingly complex. In addition to traditional requirements such as high maneuverability and high supersonic speed capabilities, there is now a demand for large amounts of power extraction from different aircraft systems. Such systems produce excessive heat that must be dissipated. To meet all these needs, the aircraft engine will play a crucial role. This work has demonstrated how large power off-takes affect not only the engine but also the aircraft in different maneuvers of a typical fighter aircraft mission. Extracting large amounts of power from the engine limits the aircraft performance in challenging maneuvers and increases engine fuel consumption in different parts of the mission. In some parts of the flight envelope, the ability to extract large amounts of power can be significantly limited to ensure safe operation of the engine.

Variable cycle engines might offer improved operability, improved engine performance, and solutions to the thermal management problem. Alongside the conventional turbofan engine, a variable cycle concept was studied, in which an additional outer bypass stream was introduced. This bypass stream is maintained by a single-stage fan on blade, FLADE. The advantages of this concept, compared to more advanced architectures, are reduced complexity and weight. The analysis indicates that the concept has the potential to improve the subsonic cruise range and the loiter endurance of a fighter aircraft. Potential improvements and limitations have been evaluated for different throttle settings across the flight envelope of the aircraft.