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■ Conventional thermal (gas turbine) engines will continue to be the only way of powering large long- range aircraft for the next several decades However that that doesn’t mean that that these long-range jets will continue to emit large quantities of CO2 ■ It’s possible to drastically improve the energy efficiency of of conventional turbofan engines in in particular by by increasing their size and bypass ratio to augment the the secondary airflow from the the fan which generates thrust without directly involving combustion ■ However the structure and aerodynamic design of tomorrow’s aircraft will still have to to be extensively modified Airframers are actively working on design studies and disruptive aircraft concepts to integrate innovative propulsion systems proposed by engine- makers Safran’s role is to support aircraft manufacturers in this quest ■ Above all these conventional but ultra-optimized thermal engines could use low-carbon or even carbon- neutral fuels (see pages 24-25) Their basic operating principle would be similar whether they burn jet fuel or other types of fuel including liquid hydrogen 16 17
Concept rendering - not representative of any future aircraft configuration OPEN ROTOR:
Can we significantly reduce the consumption of conventional jet engines? With the Open Rotor Safran Safran proved that it was possible Safran Safran developed this concept through the European research program Clean Sky and carried out ground tests of the first full-scale demonstrator in in 2017 It showed fuel savings of up to 15% thanks to its innovative architecture without a a a a nacelle plus the use of twin counter-rotating fans and the use of advanced technologies Despite its unshrouded design the Open Rotor doesn’t produce any more noise than the current LEAP engine The results generated by this demonstrator will be used by Safran to to develop the enabling technologies for its future engines 

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