Turbo-electric propulsion system of a high bypass-ratio turbofan engine for civil liner aircraft

In 2000s era, aircraft propulsion systems are achieving an outstanding level of e??fficiency. Design optimization further increases components’ performance, while lean combustion processes tend to reduce CO2 and NOx emissions. However, pollution reduction targets, especially those imposed for the next 30 years, are extremely strict and demanding, so much that conventional architectures, based on the thermodynamic Brayton cycle, can not fulfil them. Because of this main reason, alternative energies has to be taken into account, and precisely the electric one is going to be the leader. Coupling a gas-turbine engine within an electric propulsion system is one of the main challenges which aeronautical industries are facing to, but it is also one of the principal ways forward in order to meet emissions goals. This new configuration, which is actually a novelty, aimed at reducing fuel burn by feeding power to the low pressure spool through an external source, i.e. an electric motor powered by an energy storage system, like the one represented by batteries. In this way, the hybridization process takes place and the percentage of electrical power to the total required, the so called power split, is chosen as a design variable. If considering the propulsion system alone, the immediate consequence is a surprisingly reduction in fuel consumption, along with a possible weight saving coming from the fact that the low pressure turbine does not need all its stages anymore, and can be resized smaller. However, when the engine is integrated within the aircraft, something may change due to their mutual interaction; electrical components’ mass comes into play and this is one of the major parameters that is going to a??ffect the overall system. From these considerations, one can expect that there will be an optimum, i.e. a link between weight and electrical power added, that maximizes performance and minimizes emissions. Above this value, determined by actual state-of-the-art technology, trends flip backwards, and further increase the power-split setting do not brings additional benefits This last could be achieved if current limits will be pushed forward, so as to give rise to a striking revolutionary aircraft concept, the all-electric superconduction one. Superconducting technology, in a nutshell, is based on cryogenic working temperatures, in such a way to eliminate any possible losses coming from the resistance tide meets along its path. Thanks to this, electrical components’ power density drops up, and they could be shrank, solving a lot of problems and penalties related to their volume and weight. Aircraft’s hybridization process is actually the main road which will permit a huge reduction of fuel emissions and a subsequent effi??ciency increment. However, many challenges have to be coped in this process, precisely because it is something new, something involving interdisciplinarity among diff??erent engineering branches, some-thing never done before.