The overall objective of WP1 is to quantify the block and life-cycle environmental and cost benefits of the ENABLEH2 technologies relative to best-case scenario projections for reference aircraft utilizing Jet A-1, drop-in biofuels and LNG. This will be done for a number of suitably projected fuel-price and emission-taxation scenarios. More specifically the objectives of WP1 are:
- Define Concept of operations (CONOPS) based Quality Function Deployment (QFD), to down-select: – one LH2 Tube and Wing (T&W) aircraft with or without synergistic, aero-propulsive solutions, e.g. turboelectric distributed propulsion (TeDP) and/or boundary layer ingestion (BLI) devices, for short to medium range missions; and, – an LH2 Blended Wing Body (BWB) aircraft, with or without synergistic tightly-coupled aero-propulsive solutions, for long range missions.
- To provide block CO2, NOX and operating cost projections based upon ‘best-case scenarios’ for Y2050 Jet A-1, drop-in biofuels and LNG technologies, thus serving as the benchmarking datum.
- To deliver aircraft and propulsion system models (at TRL 2) of the down-selected LH2 T&W and BWB configurations.
- Technology evaluation studies to assess: – trade-offs between block fuel-burn/energy efficiency, contrails, NOX emissions and cash/direct operating costs based upon a number of defined fuel prices and emission taxation/fees scenarios; – life cycle ‘well-to-wake’ CO2 and costs based upon fuel price and emission taxation/fees scenarios and for a number of LH2 production routes.
- To adapt technology upgrades/information from other WPs into aircraft-engine integrated performance simulation models to ascertain mission level effects. This will include tech-sims/correlations for Heat Exchanger integration in the hydrogen fuel system of the aircraft (from WP2), NOx correlations for hydrogen micromix combustion (from WP3) and aircraft and system level and safety related assumptions (from WP4)
Progress and significant results
The activities in the WP began with establishing a process to undertake the down selection of the integrated aircraft- propulsion concepts. Modelling tools have been adapted and suitable models developed for the Year 2050 reference aircraft utilizing various fuels (Jet A-1, drop-in biofuel and LNG) with the end aim of quantifying the block and life-cycle environmental and cost benefits of utilizing ENABLEH2 technologies. Currently LH2 aircraft are being modelled.
Within the activities of Task 1.1 (Qualitative technology down-selection), aircraft baseline concepts have been analyzed in a two-phase down selection process. As part of phase 1 of this activity, 31 potential airframe architectures and 21 propulsion-system arrangements were considered. The second phase made the final down-selections from a short-list of nine integrated design concepts, five for the short-to-medium range (SMR) and four the long range (LR). These concepts were ranked according to 34 criteria, commonly agreed between the involved beneficiaries, relating to operating cost, revenue, noise and safety.
Eventually, established through the down-selection process, a mid-wing aircraft with fuel storage in the wing root (the Cobalt Blue concept) was selected for the SMR missions while for LR missions a BWB aircraft with turbo-electric distributed propulsion was considered most suitable. These two concepts, denoted as the “maximum synergy“ concepts, have been selected as project baselines together with two additional “lower-risk” options, having more-conventional airframes and propulsion systems and target an earlier entry into service (refer to Figures 1 and 2). This should enable the benefits of potential synergies to be quantified in clear and consistent manner.
The following are considered the key outcomes of the project till date:
- Specification of Top-level aircraft requirements (TLARs) for future aircraft technology (an illustrative example of the specified requirements for a long-range aircraft is as listed in Table 1)
- Common technical basis in terms of modelling assumptions and plausible scenarios to provide a consistent basis for the propulsion systems and aircraft-level impact analysis
- Specification of aircraft and engine technology levels and mission definitions
- Plausible fuel cost and emission taxation scenarios with additional supplemental scenarios which include the effects of electricity cost, and high/ low fossil fuel cost
- Detailed assessment of the reference aircraft designs utilizing Jet A-1, biofuels and liquefied natural gas (LNG) to compare their performance in terms of fuel burn emissions and operating costs. The markets covered in this study include short/medium-range (SMR) and long-range (LR) aircraft.
As an example, Figure 3 presents a typical analysis undertaken. The study assessed the performance of long range aircraft utilizing 2050 technologies, and their potential to reduce CO2 emissions while utilizing kerosene and alternative fuels (biofuel and LNG). The comparison is made against a 2020 baseline aircraft. A similar analysis was also undertaken for a short range aircraft and the detailed analysis and results have been presented in Deliverable D1.2 of the project.
Figure 1: Down selected short range aircraft concepts – Cobalt Blue – Max Synergy concept (left image) and Modified conventional aircraft based on the A321 Neo with LH2 tank over fuselage – low risk option (right image)(Ref- P. Rompokos, et.al 2020)
Figure 2: Down selected long range aircraft concepts – BWB based on the N3X – Max Synergy concept (left image) and modified conventional aircraft with LH2 tank over fuselage – low risk option (right image) (Ref- P. Rompokos, et.al 2020)
|Operational Stage length||3000 nm|
|Typical Passenger Weight (economic mission)||115 kg|
|Passenger Weight for Max Payload||166 kg|
Take-off and Landing
|Take off (TO) field length (Max Take Off Weight, Sea Level, ISA)||3048 m (10000 ft.)|
|Take off field length (Max passengers, High Altitude, ISA+20)||4877 m (16000 ft.)|
|Total time to climb (from 1500 ft., ISA)||25 min|
|Approach Speed (Max Landing Weight, Sea Level, ISA)||< 140 Knots (Calibrated Airspeed)|
|Landing field length (Max Landing Weight if different from Max Take Off Weight, ISA)||1768 m (5800 ft.)|
|Cabin Altitude||6000 ft.|
|Initial Cruise Altitude (ISA+10)||at least 33000 ft.|
|Design Cruise Mach Number||at least Mach 0.82|
|Max Cruise Altitude||41000 ft.|
|Airports Compatibility Limits||Code E|
Table 1: Top level aircraft requirements defined for the year 2050 long range aircraft.
P. Rompokos, A. Rolt, D. Nalianda, A. T. Isikveren, C. Senné, T. Grönstedt, and H. Abedi, 2020,”Synergistic Technology Combinations for Future Commercial Aircraft Using Liquid Hydrogen”, GT2020- 15694, ASME 2020 (Virtual conference) Turbo Expo Conference (TE20), 21-25 September 2020, London, United Kingdom,
A. Isikveren “Hydrogen – A Technically Feasible and Sustainable Fuel: “Technology Evaluation of LH2-Fuelled Aircraft”. Presented at 9th EASN Conference on Innovation in Aviation and Space, 3rd -6th September 2019, Athens, Greece.
D. Nalianda, P. Rompokos and A.Rolt ”Selection of year 2050 study aircraft airframes and propulsion systems- Introduction to the technology down-selection process” ENABLEH2 Industrial Advisory Board Meeting and workshop, 14th -15th January 2020, Cranfield, United Kingdom
WP1 has reviewed developments in H2 production and infrastructure and made projections for the long-term costs of alternative fuels. Four LH2 aircraft configurations have been selected for detailed studies (one “more conventional” and one “maximum synergy” configuration each for a typical short-medium range and long range mission). These concepts were down-selected from several aircraft configurations via a rigorous quality function deployment exercise. Assessments of reference aircraft utilising Jet A-1, biofuels and LNG is almost complete.
Within WP3, comprehensive CFD-based studies (comprising design space exploration, emissions and thermoacoustic assessments) have been completed and have highlighted limitations, uncertainties and significant discrepancies between H2 and air mixing and combustion models of 3 state-of-the-art commercial combustion CFD codes. These models will be further evaluated, validated and calibrated based on the results obtained from the experiments. The design and commissioning of the rigs are underway.
In WP4 a review of aeronautic and H2 industry safety synergies, conflicts and knowledge gaps, and preliminary hazard analyses of laboratory and aircraft systems has been completed. A safety management plan has been issued. Experimental studies are currently underway. The safety of LH2 at airports, has been assessed via a Preliminary Hazard Analysis workshop held at Heathrow.
As part of WP5, a dedicated project website and community management tool have been set up to engage with the IAB members in a formal capacity. Twelve key technology research strands have been identified for the introduction of LH2 for civil aviation as part of a preliminary roadmapping exercise.