Conceptual Design of Operation Strategies for Hybrid Electric Aircraft

Abstract

Ambitious targets to reduce emissions caused by aviation in the light of an expected ongoing rise of the air transport demand in the future drive the research of propulsion systems with lower CO 2 emissions. Regional hybrid electric aircraft (HEA) powered by conventional gas turbines and battery powered electric motors are investigated to test hybrid propulsion operation strategies. Especially the role of the battery within environmentally friendly concepts with significantly reduced carbon footprint is analyzed. Thus, a new simulation approach for HEA is introduced. The main findings underline the importance of choosing the right power-to-energy-ratio of a battery according to the flight mission. The gravimetric energy and power density of the electric storages determine the technologically feasibility of hybrid concepts. Cost competitive HEA configurations are found, but do not promise the targeted CO 2 emission savings, when the well-to-wheel system is regarded with its actual costs. Sensitivity studies are used to determine external levers that favor the profitability of HEA.

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

“…The study performed by Sahoo et al [33], highlights the beneficial aspect of a core resizing scenario on the surge margin, relative to a baseline design, when hybridized for same level of power. 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.…”

“…The Ragone diagram, as an indicator shows the relation between the achievable SP/ power density for a given SE/energy density [226]. A more suitable metric, power-to-energy ratio (P/E-ratio), is proposed by the authors under reference [34], defined as the ratio of SP to SE. Another important metric, though majorly neglected in system studies, is the "C-rate".…”

Mass, primary energy, and cost: the impact of optimization objectives on the initial sizing of hybrid-electric general aviation aircraft

“…When estimating the operating costs, predominantly VDOC components need to be adjusted for hybrid-electric aircraft. The method is explained in detail in [18], where the authors modified the cost estimation approaches from [19] and [20]. Energy and battery costs represent additional components as part of VDOC, and the calculation of maintenance costs differs.…”

Russian Aircraft Industry Innovative Development Direction Choice (On Example of Mainline Aircraft)

“…В то же время проводятся исследования роли электроаккумуляторов в ЭГСУ и их влияние на экологичность самолетов, например, для сегмента региональных ВС. В работе [11] проводится оценка полных эксплуатационных расходов (ПЭР) ВС в зависимости от уровня гибридизации силовой установки. На данный момент найденные конфигурации гибридных электрических самолетов, являющиеся конкурентоспособными по прямым расходам, не соответствуют целевым показателям по снижению эмиссии, и наоборот.…”