A leap AHEAD for aircraft of the future

By 2050, the Advisory Council for Aviation Research and Innovation in Europe (ACARE) has stated that carbon dioxide (CO2) emission, noise levels and nitrogen oxides (NOx) from air transport should reduce by by 75%, 65% and 90 % respectively. Current incremental technological improvements to existing engines cannot meet these targets.

Climate Change and Environment

A new hybrid engine with a novel propulsion system and architecture is under development by the EU-funded 'Advanced hybrid engines for aircraft development' (AHEAD)(opens in new window) project. Researchers will establish the feasibility of the hybrid engine concept for the next generation of multi-fuel blended wing body (MF BWB) aircraft. The multi-fuel BWB aircraft has the capability to carry cryogenic fuel and biofuel. The BWB aircraft has efficient high-lift wings and a wide airfoil-shaped body that could potentially increase fuel efficiency and range. The breakthrough hybrid engine design incorporates new systems. For instance, the shrouded counter rotating fans reduce required diameter and improve propulsive efficiency for the same bypass ratio. Incorporation of bleed cooling reduces fuel consumption and use of the boundary layer ingestion method for embedded hybrid engines increases engine efficiency. To reduce CO2 and NOx emissions, there is a dual hybrid combustion system (using hydrogen and biofuel under flameless conditions). Use of the MF BWB with liquefied natural gas and kerosene caused about a 65 % reduction in CO2, 80 % reduction in NOx and significant noise reduction. CO2 reduction is more for the liquid hydrogen (LH2) version, but the life cycle CO2 cost of LH2 has yet to be calculated. Results so far have exceeded the planned objectives. The preliminary design of the BWB aircraft is complete. The hybrid engine architecture has been optimised. The bleed cooling system has been defined and the heat exchanger is being evaluated for patent submission. Computational fluid dynamic simulations helped in selecting the best geometry for the hydrogen combustion chamber that is now being manufactured. To assess the impact on global warming, the effect of water vapour, CO2 and NOx emissions from the AHEAD aircraft with hybrid engines was evaluated. Special attention will be given to the impact of water vapour that condenses into contrails at high altitude and which is thought to have a global warming effect. The AHEAD hybrid engine will constitute a massive leap forward in terms of environmental friendliness. The BWB configuration along with the proposed hybrid engine concept promises to bring in the much required breakthrough in civil aviation technology.