Low-Fuel Consumption Gas Turbine Engines for Extended-Range UAVs

In the last years the interest in Unmanned Air Vehicle systems has greatly raised, thanks to their extended operation capabilities. Among the reasons of this growing interest there is the development of very efficient and reliable guiding systems, that allow a thorough remote vehicle control. The endurance capability is certainly one of the most important UAV characteristics, because some missions are supposed to last even more than one day. For this reason, the engine fuel consumption becomes a fundamental aspect. The turboprop engine is commonly used in this kind of missions, with powers in the range between 300-900 kW. To extend the flight range and the endurance characteristics, it is important to have low-fuel consumption propulsion systems. At this purpose, a turboprop engine with intercooling and regeneration has been studied. A thermodynamic numeric program that simulates the behavior of a turboprop with regeneration and intercooling at different engine and operating conditions has been developed. The program allows to compute the thermodynamic working cycle and hence the main engine performances, as specific power, thermal efficiency and specific fuel consumption. An off-design analysis is performed to evaluate the engine behavior when operating at different conditions respect to the design point. An example case, showing the saved fuel for a particular mission profile, is then reported.