Research on inlet precooling for mini-turbojet engines

High speed and high altitude UAV and Mini-UAV flight requires certain qualities from the installed engine(s). The use of turbojets for this purpose is justified, though, the engines can show for some maneuvers a lack of performance, which might be countered with inlet precooling. This paper describes the research done at the RMA on inlet precooling. Mainly the influence of precooling on the thrust and the TSFC of the SR-30 mini turbojet is covered. Here, the precooling is obtained actively, through injection of liquid nitrogen in the engine inlet, and passively, via a helicoidal heat exchanger. Theory and experiments are compared and the influence of icing on the performance of the engine is discussed. This study can also be of some interest for propulsion concepts using inlet mass injection like the MIPCC for the RASCAL concept or for UCAV propulsion.