Adaption of a Turbofan Engine for High Power Offtakes for a Turbo-electric Propulsive Fuselage Concept

Paper in proceeding, 2019

To lower the fuel consumption and its associated emissions, several new aircraft concepts are being investigated. One such concept is the turbo-electric propulsive fuselage concept (PFC) that is being studied in the EU Horizon 2020 project CENTRELINE for a 2035 entry into service (EIS). The PFC makes use of a rear-mounted electric fuselage fan to ingest part of the fuselage boundary layer. The fuselage fan is powered by power offtakes from two under-wing podded geared turbofans. In this paper, a design of the under-wing main power plants is presented and compared to an engine for a conventional reference aircraft with the same EIS year. A free power turbine (PT) stage for the large power offtake required is added aft of the low pressure turbine (LPT). The PT is connected to an electric generator on the same shaft that is integrated in the PT hub. The addition of the PT allows for mechanically decoupling the electric machinery from the LP spool, which is considered beneficial for the electric machinery operation. It also allows for a removal of one LPT stage compared to the reference engine. The power plants for the PFC show a reduction of fan diameter by 11%, as well as a reduction in engine weight of 13% excluding the electric machinery weight.