Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - CENTRELINE (ConcEpt validatioN sTudy foR fusElage wake-filLIng propulsioN intEgration)

Teaser

In order to reduce aviation’s environmental footprint and to enable aviation\'s sustainable growth in the long-term, the exploration of breakthrough technological advancements is crucial. Great potential for significant contributions to achieving these goal settings is...

Summary

In order to reduce aviation’s environmental footprint and to enable aviation\'s sustainable growth in the long-term, the exploration of breakthrough technological advancements is crucial. Great potential for significant contributions to achieving these goal settings is expected from novel propulsion systems and their more synergistic integration with the airframe. The CENTRELINE project aims to demonstrate the proof of concept for such a ground-breaking approach to synergistic propulsion-airframe integration, the so-called Propulsive Fuselage Concept (PFC). The PFC features a turbo-electrically driven propulsive device at the aft-fuselage that entrains and re-energises the fuselage boundary layer flow in order to directly compensate the viscous drag effects in the fuselage wake field.
The positive effect of “wake-filling” on propulsive power requirements has long been known from the field of marine propulsion. Ship propellers are typically located at the aft-body of the vessel and operated within the boundary layer flow close to the ship’s body surface. The physical principle utilised in this configuration is known as Boundary Layer Ingestion (BLI) or wake-filling propulsion integration. It is also applicable to airborne systems. For large commercial aircraft, the share of viscous and form drag typically ranges between 60–70% of the total drag in cruise. Approximately half of this share can be attributed to the fuselage body, making it the most interesting airframe component to be utilised for the purpose of wake-filling propulsion integration. With its single boundary layer ingesting propulsor the CENTRELINE PFC realises fuselage wake-filling in the most straightforward way while intrinsically offering the full fuselage wake-filling potential (360° installation).
Building upon the promising results of the preceding EU funded project DisPURSAL (GA no. 323013), CENTRELINE matures the PFC technology by building scaled-down models that will be tested in a wind tunnel. In parallel, the project\'s researchers perform high-fidelity numerical simulations for key aspects of the overall aircraft design, and, apply integrated design optimization techniques in order to maximise the benefits obtainable from fuselage wake-filling propulsion integration.
The specific high-level targets of the project include:
• 11% CO2 reduction against an advanced conventional reference aircraft equipped with aerodynamic, structural, power plant and systems technologies suitable for a potential Entry Into Service (EIS) year 2035, the “R2035”.
• 11% reduction of NOx emissions against the R2035.
• Technology Readiness Level (TRL) 3-4 for the Propulsive Fuselage Concept at the end of the project.

Work performed

The CENTRELINE project started by defining an advanced reference aircraft in conventional configuration for an EIS in 2035. In order to form a solid basis for a fair evaluation of the PFC technology, the “R2035” reference aircraft was derived from an existing aircraft representing year 2000 in-service technology, however, equipped with realistically advanced technologies for a potential aircraft product EIS in 2035. For both advanced aircraft, the R2035 and the PFC, a consistent set of top-level requirements was defined. Based on an analysis of air traffic demands and aircraft market development trends towards 2035, the medium-to-long range, wide-body aircraft segment was identified as the most impactful scenario for PFC technology introduction.
The project then proceeded with the down-selection of a most suitable PFC aircraft configuration from a pool of eligible configurational candidates. Based on parametric design space exploration and preliminary aircraft integrated sizing studies, an initial PFC target aircraft design was specified including key requirements for the design and performance of the major aircraft components and subsystems. An initial 2D aero-shaping for the PFC configuration was defined, and, design concepts for key structural components were developed. In parallel, a framework for the collaborative workflow in the project was deployed, together with an efficient data integration process for aircraft multi-disciplinary design and optimisation.
For the PFC experimental validation, the design specification of the modular wind tunnel model was completed. The wind tunnel model has been manufactured and is ready for testing. Initial wind tunnel testing of the unpowered PFC configuration was successfully performed. Two fan designs for rig testing were developed. The first one was optimised for undistorted inflow conditions, a second one was optimised for PFC-specific inflow distortion. The design of the employed BLI fan test rig was modified in order to accurately represent the CENTRELINE PFC application case.
The architecture of the PFC turbo-electric power train and its key properties such as power transmission type and system voltage levels have been defined. The initial design and performance of the main power plants have been established, a preliminary assessment of generator integration options within the PFC main power plants was performed, and, the preliminary design of turbo-electric power train components including electric machinery and associated cooling systems was performed.

Final results

Based on a strong partnership between industry, research and academia, CENTRELINE is set up to maximise the impact of the PFC technology on global emissions and climate, European leadership and the social acceptance of aviation. The project matures the concept of fuselage wake-filling propulsion integration for large commercial aircraft application from TRL 1-2 to TRL 3-4. In CENTRELINE, a thorough understanding of the aerodynamic effects of fuselage wake-filling propulsion integration is developed. Solutions for a synergistic aero-structural design integration of the BLI propulsor are elaborated, together with the layout and design of the fuselage fan turbo-electric drive train. The multi-disciplinary systems design solutions are consistently integrated and optimised at the aircraft level. The output of CENTRELINE is tailored for rapid further technology maturation to TRL 6 by 2030. With its 11% CO2 reduction target and application to the highly impactful medium-to-long range wide-body aircraft market segment, CENTRELINE technology has the potential for a significant decrease of aviation’s global emissions.
In CENTRELINE, several PhDs researchers are working on various topics of interest to the aircraft and propulsion system community. The publications produced through this research will be relevant to a large community of academic and industry researchers. The investments made in research and innovation in the CENTRELINE project and beyond will secure and generate highly skilled education and employment in industry as well as in academia.
In order to maximise the impact of work performed in CENTRELINE, its results are disseminated continuously through scientific publications, a high number of publically available project reports, as well as frequent news updates, and dedicated public workshops announced through the project website and social media channels.

Website & more info

More info: https://www.centreline.eu/.