Aircraft Engine Technology Review - The Pathways for an Efficient, Cleaner and Quieter Aviation Industry 2019-36-0175

The aviation industry has been submitted to a set of environmental and commercial drivers that have led it to pursue engine technologies focused on the efficiency improvement, greenhouse (CO₂) and pollutant (NO_x and PM) emissions reductions, as well as noise abatement.The effort to comply with the ambitious long term environmental and efficiency targets set by the regulatory authorities has driven the aeronautic industry in a technological research effort. In the medium term, the aviation industry's strategy for commercial aviation is to focus on the advanced, but rather conventional propulsion systems (mainly turbofan engines). In this scenario, technological efforts have focused basically on enhancing thermal efficiency, through advanced core engines, as well as improving propulsive efficiency, through the use of low pressure systems (basically reduced pressure ratio and increased engine bypass ratio). To reach these objectives, a set of technological platforms has been proposed, with some already on an operational/commercial level, while others still in a prototype category. In this context, engine manufacturers have given a special focus on some technological approaches, like Ultra High Bypass Ratio (UHBPR) Geared Turbofans (GTF), Three Spool Turbofan (3STF), Counter-Rotating Open Rotor (CROR), Intercooled Turbofan (ITF) and Bleedless Engine (BE). This work is supposed to present, into a review format, an overview of the aforementioned technology platforms, demonstrating their potential to meet the efficiency and environmental requirements, their maturity level, as well as report any cases of operational experience available in the technical literature.