A new aircraft propulsion system to cut CO2 emissions
Air traffic volumes are projected to double by the mid-2030s, with CO2 emissions from aircraft expected to do likewise without new fuel-efficient aircraft entering the market. EU-funded researchers are exploring a propulsion method to reduce fuel use and greenhouse gas emissions - good for the environment and the industry's competitiveness.
© Bauhaus Luftfahrt e.V.
To ensure the long-term sustainability of aviation, big reductions in the amount of CO2 aircraft emit are vital. Given the highly optimised systems fitted on aeroplanes, this cannot be achieved through small changes and adjustments. Instead, breakthrough concepts and technologies are needed.
One such concept concerns a propulsive fuselage, which is being explored and initially tested under the EU-funded CENTRELINE project. It features an electrically driven propulsive device located in the back of the fuselage to deal more efficiently with the effects of drag caused by the flow of air around the aircraft. The innovation is a way to improve an aircrafts flight efficiency and reduce fuel use.
The system is expected to cut CO2 emissions by 11 % as compared to the kind of conventional aircraft likely to be entering into service by 2035. By maximising the benefits of propulsive fuselage technology, the project seeks to lower the aviation sectors impact on climate change and thus to make flying more socially acceptable.
The competitiveness of the European aviation industry is based on its ability to provide programmes for commercial transport that meet the needs of airlines and other stakeholders at the lowest operating cost, says project coordinator Arne Seitz of Bauhaus Luftfahrt in Germany.
CENTRELINE is opening up the potential to put Europes aviation sector in a leading position for entering the global market with propulsive fuselage technology. To transfer our research results to industry, we are focusing on novel technologies with industrial relevance and close collaboration between universities, research institutes and major European manufacturers.
Dealing more efficiently with drag
The basis of the concept is a single fan encircling the rear of the fuselage and driven from generators on the underwing engines. The fan should make it possible for the aircraft to ingest and re-energise much of the boundary layer flow. This is the airflow resulting from friction on the surface of an aeroplane as it moves through the air and the source of 60-70 % of drag on large commercial aircraft.
CENTRELINEs researchers are building a scale model of the system to be tested in a wind tunnel in order to assess its overall configuration, while the aerodynamics of the fuselage fan will be measured in test rigs. The researchers will also perform computerised simulations and apply a range of techniques to optimise the system design.
Further aircraft innovation
Under the current project, the readiness level of the technology is to be raised from the formulation of the concept to its initial validation in a laboratory setting, with a view to continuing the work in subsequent phases and initiating product development by 2030. Moreover, the concept increases the potential for innovation in other elements of aircraft design.
The CENTRELINE concept may be one of very few opportunities to successfully apply hybrid and electric mobility to large commercial aircraft, explains Seitz. The approach combines novel propulsion system technology with a proven tube-and-wing aircraft layout, which has great potential for future innovation. This potential is further strengthened by the concept being complementary to other technologies that address the thermal or propulsive efficiency of power systems, wing aerodynamics and lightweight aero-structural technologies.