An electrically driven fan at the end of the fuselage sucks in the fuselage boundary layer, thereby improving propulsion efficiency. The research work was carried out in the ADEC (Advanced Engine and Aircraft Configuration) project as part of the European Clean Sky 2 programme.
Greater efficiency thanks to hybrid-electric drive and boundary layer-injecting drive unit
The potential of new propulsion technologies and a "canard" configuration
How can we make the air transport of the future more environmentally friendly? The BLI-Canard model provides exciting answers. It utilizes innovative technologies that could significantly reduce the energy demand and emissions of regional, short and medium-haul aircraft.
The key component of this model is a hybrid-electric propulsion system combined with a boundary layer ingestion (BLI) engine. This concept was investigated by our institute as part of the European Clean Sky 2 project ADEC (Advanced Engine and Aircraft Configurations) together with various DLR institutes and partners from all over Europe - including renowned institutions such as ONERA, TU Delft, NLR and the industrial giants Airbus and Rolls-Royce. The aim is to achieve the ambitious climate targets set by the European Commission as part of Flightpath 2050.
Our model: innovation meets efficiency
The BLI Canard model combines pioneering technologies in an impressive design. Two turbofan engines under the wings provide the main thrust and simultaneously drive generators that continuously supply a motor at the rear of the fuselage with electrical power. This motor drives the BLI fan, which sucks in the boundary layer - i.e. the flow decelerated by friction on the fuselage. However, in contrast to the almost undisturbed inflow of the wing mounted engines, the flow field within the boundary layer exhibits significant local differences in velocity. These are compensated for by a special design of the fan blades of the BLI fan. The combination of the reduced inflow velocity and the adapted fan design ultimately enables an improvement in efficiency and thus a reduction in the power required for the entire aircraft.
An integrated battery serves as energy storage and can support the BLI fan and the remaining turbofan in emergencies - for example in case of a gas turbine failure. The turbofan's generator works as a motor and is supplied with electrical power. This allows the gas turbines to be optimised specifically for cruise flight, which improves their efficiency during regular operation compared to a conventional turbofan architecture.
Why the "canard"configuration?
The name "Canard" is derived from the special tailplane arrangement, in which the horizontal stabilizer is located in front of the wing. In the model shown, the winglets at the wingtips also act as vertical stabilisers. This configuration offers a significant advantage for the use of a BLI fan, as it reduces the local flow disturbances caused by the wake of the stabilizers reaching the BLI fan and thus increases its efficiency.
