Thermodynamic characteristics of a turboprop engine with heat exchangers for unmanned aerial vehicles

UAVs are becoming of always greater importance, both in military and civil applications. One of the main reasons of their growth is the realization of very efficient and reliable guiding systems, that allow a thorough remote vehicle control. An important UAV aspect is the endurance capability. A flight length of 24 hours or more is often required for their missions. This makes the engine fuel consumption a fundamental aspect. For a power range comprised between 300 - 900 kW, the turboprop engine is commonly used. To reduce the engine fuel consumption, and consequently increase the UAV endurance characteristics, a turboprop with intercooling and regeneration has been studied. Regeneration is a techniques that allows to recover the exhaust gas heat at the power turbine outlet, to pre-heat air at the combustion chamber inlet. This allows to reduce the specific fuel consumption. The intercooled compression process allows to reduce the compressor absorbed power and consequently rise the output power. A thermodynamic numeric program that simulates the behavior of a turboprop with regeneration 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 offdesign analysis is then performed to evaluate the engine behavior when operating at different conditions respect to the design point. © 2013 by Roberto Andriani.