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Forschungszentrum Jülich - Annual Report 2011

Annual Report 2011 | Forschungszentrum Jülich SharingKnowledge 65 T he frictional resistance is deter- mined by air swirling around the wings during flight – experts re- fer to this as turbulent flow. The flow resistance can be decreased us- ing special structures on the surface of the wings – such as those that scien- tists have copied from shark skin. Re- searchers from two of Jülich’s institutes and four institutes at RWTH Aachen Uni- versity want to join forces and go a step further: they want to influence the tur- bulent boundary layer by means of a structured wing surface that continu- ously actively changes it shape trans- verse to the main flow direction. This causes a wave-like upward and down- ward movement, which also varies across the wing. In 2011, the scientists from JARA-EN- ERGY convinced German Research Foundation (DFG) reviewers that their research project should receive funding and it is now supported as research unit FOR 1779. The results of a seed fund project provided the basis for the suc- cessful application. JARA uses seed funds to support projects that are still in the ideas or start-up phase. This sup- port enabled the scientists to set up an experiment, for example, that made it possible to reduce the flow resistance over a flat plate by up to 9 % using wave-like movements of the surface. The next step involves constructing a model in which centimetre-sized ele- ments (actuators) will actively change the shape of an aluminium plate around a hundred times per second. During this process, the JARA researchers will measure the flow resistance in a wind tunnel. The actuators are made of a ma- terial that expands when an electric field is applied. This construction meth- od will be transferred at a later date to wing-like forms. “Within the research unit, our main objective is to test the ex- tent to which aluminium wing plates fa- tigue because of the constant rapid de- formations – in other words, the extent to which they are damaged,” said Prof. Tilmann Beck from the Institute of Ener- gy and Climate Research. The Central Institute for Electronics, in contrast, concentrates on developing an actuator and sensor network for the regulated fine-meshed and temporally precise de- formation of the surface. Saving fuel is just as important for air traffic as it is for road traffic – and not just for economic reasons. Dwindling resources must be conserved and the climate protected. Researchers in the ENERGY section of the Jülich Aachen Research Alliance (JARA) are working on reducing the frictional resistance of aircraft and thus cutting their kerosene consumption. JARA-ENERGY Saving Energy with Active Wings Vortex structures (right) directly over a plate, the surface of which changes shape transverse to the air stream. JARA researchers want to apply the principle of active deformation to wings.