DESIGN APPROACH FOR HYBRID ELECTRIC PROPULSION CONCEPTS OF MID-RANGE AIRCRAFT INCLUDING SUSTAINABLE AVIATION FUELS

The aviation industry is facing an urgent need to address the environmental impact of air traffic. This isunderlined by the Flightpath 2050 agenda of policymakers and the aerospace industry, which has the ambitiousgoals of reducing CO2 emissions by 75 %, NOx emissions by 90 %, and noise emissions by 65 % until 2050compared to typical capabilities of new aircraft in 2000. Various technologies are promising solutions to tacklethese goals; for example, efficient propulsion concepts, such as Distributed Hybrid Electric Propulsion (DHEP),allow the reduction or even elimination of pollutant emissions through full-electrical operation at ground levels (<900 m). Another promising option is the use of Sustainable Aviation Fuel (SAF) to reduce chemical emissionsdirectly at the source. This study takes up the potential of DHEP and SAF operation, introducing a designapproach for hybrid electric powertrains of mid-range aircraft based on the 0D in-house tool ASTOR for thethermodynamic cycle performance calculation of gas turbines. It has been adapted for on-design calculationsand extended by a combustion chamber model to enable the determination of combustion emissions of SAFs.Two approaches, 0D-chemical equilibrium (CE) and 0D-chemical reaction network (CRN), were employed tomodel the emissions of the combustion process and integrated into the hybrid electric powertrain model usinglookup tables. The hybrid electric powertrain model represents a propeller-based DHEP architecture, the gasturbine consisting of a compressor and turbine, as well as the combustion chamber. Appropriate boundaryconditions are applied to investigate different propeller-based DHEP concepts. Subsequently, a Design ofExperiments-based (DoE) design process is conducted for the SAF powered gas turbine of the hybrid electricpowertrain for take-off conidtions providing insights into power-specific fuel consumption (PSFC) and chemicalemissions, offering a database enabling new assessments of air pollution at ground level and a pollution drivendesign selection.