Flight-Like Recuperator for Model 250 Engine

Recuperators are heat exchangers that can significantly improve the fuel efficiency of gas turbine (GT) engines. Recuperated gas turbines have the potential to enable large improvements in the capabilities of small Unmanned Aerial Vehicles (UAVs). Although these advantages have been recognized for some time, recuperated gas turbines have not been used in aircraft because conventional heat exchangers are not compact or durable enough. Previously we developed and demonstrated a recuperator for the Model 250 engine (Knaus 2020). This recuperator was developed for an engine test but was not intended to be used for flight. We successfully demonstrated good thermal performance and high durability, but the prior recuperator was too heavy and large for flight. In a subsequent program, we have developed a “flight-like” recuperator for the Model 250 engine. The flight-like recuperator was developed to fit within the spatial constraints of a helicopter and to minimize the installed mass of the recuperator. The flight-like recuperator is a microchannel heat exchanger that was developed using the same operating principle and fabrication methods as the previous core, however the plate design was changed significantly. The flight-like recuperator was tested on a Rolls Royce Model 250 C47/D engine. The recuperator significantly lowered specific fuel consumption (SFC) of the engine, consistent with modeling predictions, and survived 22 starts, 15 durability cycles, and 6 hours of run time. Installed mass and the SFC benefit are presented from the engine test.