Emission-free flying is a major goal of European politics, an important component of the "European Green Deal" persued by the EU Commission, which is to make Europe climate-neutral by 2050. The energy consumption of an aircraft is significantly influenced by its wing shape - the higher the aspect ratio of a wing, the less drag it produces in relation to its lift.
Climate-friendly wing design
High aspect ratio (i.e. "elongated") wings of future aircraft will be very elastic in order to keep the weight of the wing structure low. The use of carbon fibre reinforced plastic (CFRP) offers the possibility of building lightweight wings, the deformation of which can be optimized for the cruise flight by using suitable materials. This so-called “aeroelastic tailoring” also makes it possible to reduce the stresses on the wing structure that arise in flight during large manoeuvres and strong gusts.
Two wing models in the wind tunnel
The DLR Institute for Aeroelasticity in Göttingen has been a pioneer in the development of such innovative concepts for wing structures for many years, and is part of a European research network. Specifically, there has been a long-term cooperation in the areas of numerical simulation, wind tunnel tests and the structural dynamic identification of commercial aircraft, with the French aviation research institute ONERA.
In the current joint project FIGURE (Flexible WIng GUst Response), two models of an elastic wing have now been tested in a wind tunnel in Paris. One wing was developed by DLR and one wing by ONERA with different design approaches. Both models were built in Göttingen and tested in a wind tunnel in Paris at flow velocities close to the speed of sound, similar to the speeds achieved by an Airbus or Boeing transport aircraft. In the experiment, a so-called gust generator was used to generate disturbances that stimulate the wings to vibrate, and the resulting forces on the wings, as well as the wing deflections, were measured.
Common evaluation of measured data
Like many international activities, the course of the FIGURE project was influenced by the corona situation: A joint test campaign was planned by DLR and ONERA in Paris, which, due to travel and contact restrictions in both countries, has now been carried out by ONERA colleagues alone, only virtually accompanied from Göttingen. The evaluation of the measurement results and the comparison with numerical simulations will now take place together again. The analysis will provide information about which new approaches for the design of wing structures are suitable for making the future generation of transport aircraft fly even more energy-efficiently.
