Cycle Selection and Sizing of a Single-Aisle Transport with the Electrically Variable Engine(TM) (EVE) for Fleet Level Fuel Optimization

A Review of Concepts, Benefits, and Challenges for Future Electrical Propulsion-Based Aircraft

“…Furthermore, this concept benefits from requiring a reduced size conventional engine to meet operational requirement under one engine inoperative (OEI) condition [34]. Due to the simplicity of parallel hybrid electric configuration, the concept has been widely explored by multiple bodies in different projects: SUGAR Volt, United Technology Research Centre (UTRC)-Geared Turbofan design [31,35,36], Rolls-Royce North America (RRNA)-Electrically Variable Engine (EVE) [37][38][39], Bauhaus Luftfahrt (BHL) conceptualized designs [40], TRADE [41], etc. Such configurations inherently deprive the aero-propulsive synergistic benefits, if propulsors are not strategically placed close to the wing body surface of the aircraft.…”

“…Many of the electric aircraft designs were conceptualized utilizing the benefits of BLI, under a highly or moderately DEP environment. NASA N+3 generation aircraft, N3-X design utilizes the thick boundary layer atop the planform to ingest to the electrically powered ducted fans embedded in a BWB airframe [39]. Such arrangement gives the opportunity for partial compensation of the wake created by the vehicle and thus, reduces the thrust requirement [23].…”

“…The engine is designed to meet the full thrust requirement, however, utilizes battery power to reduce fuel burn and overall emissions. In an optimized scenario, the design gives opportunity for 24% fuel and 7% energy savings over a 900 nm mission range [37,39]. UTRC conceptualized parallel hybrid electric design was built on the underlying concept of boosting the gas turbine operation with battery power during take-off and landing mission segments.…”

“…A comprehensive understanding of the trends and impact on the propulsion system size and performance is needed to determine when to supplement with battery energy and how big the battery size should be [90]. This is considered as an optimization problem and covered in a few studies [38,39,89]. From the performance perspective, utilization of a battery in a stepped profile have less impact on the battery life than using it for ramping power during the take-off and climb, especially if the high current is drawn in a low state-of-charge [91].…”

NASA’s Magnetic Gearing Research for Electrified Aircraft Propulsion

“…System-level studies have been performed on a number of vehicle concepts that use EAP. These studies have shown the feasibility of achieving system-level benefits to energy consumption, fuel burn, and/or emissions [3][4][5][6][7][8][9].…”