Periodic Reporting for period 2 - CENTRELINE (ConcEpt validatioN sTudy foR fusElage wake-filLIng propulsioN intEgration)
Periodo di rendicontazione: 2018-12-01 al 2020-11-30
Novel propulsion technology and propulsion-airframe integration play a key role in enabling aviation's long-term sustainability. Strong improvements of vehicular propulsive efficiency may be achieved by fuselage wake-filling propulsion integration, i.e. the ingestion and re-energisation of the fuselage boundary layer by the propulsion system. 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 also applicable to airborne propulsion. The CENTRELINE project aimed at maximising these benefits under realistic systems design and operating conditions. The project was dedicated to demonstrating the proof of concept and initial experimental validation for the most straight-forward approach to fuselage wake-filling, the so-called Propulsive Fuselage Concept (PFC). The CENTRELINE PFC aircraft features a single, turbo-electrically powered fan encircling the very aft-section of the fuselage for full annular (360°) Boundary Layer Ingestion (BLI). The specific high-level targets of the project included the maturation of the PFC technology to Technology Readiness Level (TRL) 3-4 at the end of the project, which has been achieved. Together with this key technology development objective, ambitious performance targets of 11% CO2 and NOx emission reductions were defined relative to an advanced conventional reference aircraft equipped with technologies suitable for a potential entry-into-service year 2035. Based on the fully integrated multi-disciplinary aircraft design, the CO2 reduction of the turbo-electric PFC aircraft results in 4.7%. The PFC NOx emissions during ICAO Landing and Take-off (LTO) cycle are reduced by 1.8% and cruise NOx is 20% lower than for the R2035.
Pursuing the conceptual proof, all main challenges associated with fuselage wake-filling propulsion integration in a turbo-electric PFC aircraft were tackled. A thorough understanding of the aerodynamic effects of 360° fuselage BLI was developed through extensive aero-numerical simulations and experimental testing in a laboratory environment. Optimised aerodynamic predesigns were produced for the BLI fuselage fan and the aft-fuselage section. Conceptual solutions for the aero-structural integration of the BLI propulsive device and the turbo-electric powertrain were elaborated. The developed design solutions have been either analytically or experimentally verified to demonstrate TRL 3 for the PFC technology. The CENTRELINE aircraft configuration was studied in low-speed wind tunnel experiments at relevant flow incidence angles. The 3D numerically designed fuselage fan was tested on a low-speed rig at relevant operating conditions. The scale-model experimental results were extrapolated to full speed and scaled based on extensive CFD numerical analyses. As such, initial steps towards experimental validation in a laboratory environment (TRL 4) have been taken. All detailed design and analysis results were incorporated in a multi-disciplinary PFC aircraft design optimisation. A roadmap for the future development of the PFC aircraft technology towards TRL 6 by 2030 has been devised in order to support a potential service entry of the PFC aircraft in 2035.
The PFC technology was rigorously benchmarked against a similarly advanced but conventional aircraft, the R2035. The PFC benchmarking covered aircraft-integrated performance and Cash Operating Cost (COC) assessments, as well as an evaluation against the environmental targets set by the ACARE Strategic Research and Innovation Agenda (SRIA) for the year 2035. Both aircraft, the PFC and the R2035 were pre-designed and sized to a realistic set of Top-Level Aircraft Requirements (TLARs) in accordance with common industrial practices in aircraft family design. The set of TLARs based on a future market analysis that showed a mid-to-long range air transport task featuring 340 passengers and 6500nmi design range to be the most impactful scenario.
The CO2 and NOx emissions of the turbo-electric PFC configuration were assessed based on an optimised 2D PFC aero-shaping, assuming Lean Direct Injection combustion technology for the year 2035 engines. Based on a fully integrated multi-disciplinary aircraft design and performance synthesis, the CO2 reduction of the turbo-electric PFC was determined to be -4.7% against the R2035 or -36% relative to the year 2000 SRIA baseline. The PFC NOx emissions during ICAO LTO cycle were assessed to be -1.8% versus the R2035. Cruise NOx emissions of the PFC aircraft were -20% relative to the R2035 and -64% when compared to year 2000. The equivalent perceived noise levels of the PFC aircraft according to ICAO certification were found to be similar to the R2035, meaning a cumulative noise reduction of 12EPNdB relative to a year 2000 aircraft. The design mission COC for the PFC aircraft was assessed to be lower than for the R2035 as soon as the fuel price increases beyond US$ 1.5 per gallon, even if fuel taxation or carbon pricing and offsetting cost for the year 2035 are neglected.
CENTRELINE partners disseminated results in 7 journals and participated at 9 conferences. A Policy Maker Workshop was organized (Brussels, 2019) and dedicated CENTRELINE sessions have been held at ISABE and EASN conferences (2019). At the EC Aerodays (Bucharest, 2019) the wind tunnel model and a section of the fuselage fan blading were displayed. An animation video and a mock-up, featuring the PFC technology, have been produced.
The PFC technology was rigorously benchmarked against a similarly advanced but conventional aircraft, the R2035. The PFC benchmarking covered aircraft-integrated performance and Cash Operating Cost (COC) assessments, as well as an evaluation against the environmental targets set by the ACARE Strategic Research and Innovation Agenda (SRIA) for the year 2035. Both aircraft, the PFC and the R2035 were pre-designed and sized to a realistic set of Top-Level Aircraft Requirements (TLARs) in accordance with common industrial practices in aircraft family design. The set of TLARs based on a future market analysis that showed a mid-to-long range air transport task featuring 340 passengers and 6500nmi design range to be the most impactful scenario.
The CO2 and NOx emissions of the turbo-electric PFC configuration were assessed based on an optimised 2D PFC aero-shaping, assuming Lean Direct Injection combustion technology for the year 2035 engines. Based on a fully integrated multi-disciplinary aircraft design and performance synthesis, the CO2 reduction of the turbo-electric PFC was determined to be -4.7% against the R2035 or -36% relative to the year 2000 SRIA baseline. The PFC NOx emissions during ICAO LTO cycle were assessed to be -1.8% versus the R2035. Cruise NOx emissions of the PFC aircraft were -20% relative to the R2035 and -64% when compared to year 2000. The equivalent perceived noise levels of the PFC aircraft according to ICAO certification were found to be similar to the R2035, meaning a cumulative noise reduction of 12EPNdB relative to a year 2000 aircraft. The design mission COC for the PFC aircraft was assessed to be lower than for the R2035 as soon as the fuel price increases beyond US$ 1.5 per gallon, even if fuel taxation or carbon pricing and offsetting cost for the year 2035 are neglected.
CENTRELINE partners disseminated results in 7 journals and participated at 9 conferences. A Policy Maker Workshop was organized (Brussels, 2019) and dedicated CENTRELINE sessions have been held at ISABE and EASN conferences (2019). At the EC Aerodays (Bucharest, 2019) the wind tunnel model and a section of the fuselage fan blading were displayed. An animation video and a mock-up, featuring the PFC technology, have been produced.
CENTRELINE fully reached its technology maturation goals and has thereby pushed the state of the art for PFC aircraft to TRL 3-4. In order to efficiently facilitate follow-on research and innovation actions, CENTRELINE has devised a clear roadmap for the PFC technology towards target TRL 6 in 2030.
The CENTRELINE technology concept features a particularly high innovation potential when compared to other disruptive aircraft configurations, as its environmental benefits are directly linked to the classic tube-and-wing arrangement. The baseline PFC arrangement features a high degree of synergistic compatibility with other highly advanced technologies, especially revolutionary core engines, high-temperature superconduction, ultra-efficient wing technologies or hydrogen fuel technology. As such, CENTRELINE has successfully made its contribution to achieving the FlightPath2050 emission goals.
CENTRELINE has formed a strong team of leading research and industrial stakeholders supporting Europe’s leading position in aviation. Several PhDs researchers have been working on topics of high interest to the aeronautical 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 were disseminated intensively through scientific publications, a high number of publicly available project reports, as well as frequent news updates, and dedicated public workshops announced through the project website and social media channels.
The CENTRELINE technology concept features a particularly high innovation potential when compared to other disruptive aircraft configurations, as its environmental benefits are directly linked to the classic tube-and-wing arrangement. The baseline PFC arrangement features a high degree of synergistic compatibility with other highly advanced technologies, especially revolutionary core engines, high-temperature superconduction, ultra-efficient wing technologies or hydrogen fuel technology. As such, CENTRELINE has successfully made its contribution to achieving the FlightPath2050 emission goals.
CENTRELINE has formed a strong team of leading research and industrial stakeholders supporting Europe’s leading position in aviation. Several PhDs researchers have been working on topics of high interest to the aeronautical 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 were disseminated intensively through scientific publications, a high number of publicly available project reports, as well as frequent news updates, and dedicated public workshops announced through the project website and social media channels.