Powerplant Pre-Design Studies for a Turboelectric Propulsive Fuselage
The conceptual design of the turboelectric drive train for a Propulsive Fuselage Concept is one of the research areas investigated as part of the European Union-funded research project CENTRELINE. In this context, pre-design studies of major systems were conducted at Bauhaus Luftfahrt. The power transmission concept is characterised by wing-installed geared turbofan (GTF) engines specifically designed to allow for power off-takes required for the operation of the fuselage-installed electric propulsor. These power extractions are significantly greater than the amount typical for aircraft subsystems and may have a strong impact on the power balance of the engine spools. The powerplant off-design study presented in the upper figure on the right page shows the implications of varying operational power extraction levels for a design off-take representing 15 % of the low-pressure turbine power output. For comparison, the part power characteristic of a conventional GTF is shown as well. As can be seen, the extraction variability during off-design operation is constrained by several operating limits of the associated turbo components.
Important results on the design and operating characteristics of the fuselage-installed propulsor can be derived from the figure below. It has been established that freestream total pressure recovery ratio (p2/p0) – a parameter that is typically impaired in case of propulsors working in the boundary layer – has a significant impact on the performance characteristics. Beside the implications of design fan pressure ratio variations, the second figure shows the pronounced effect of p2/p0 on fan diameter and required shaft power at take-off conditions.
This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 723242.
- Investigation of significant power off-takes: The graphic indicates the impact of operational variations in relative off-take from the low-pressure spool on TSFC. Feasible power off-takes are constrained by operating limits of associated turbo components.
- Sizing study of the fuselage fan propulsion system: Impact of the boundary layer-impaired intake total pressure recovery ratio and the design fan pressure ratio on dimension and take-off performance of the fuselage fan propulsion system