The German Research Foundation (Deutsche Forschungsgemeinschaft; DFG) is funding a new research group that will be dedicated to investigating open issues relating to the complex aerodynamics of aircraft at transonic speeds, under the scientific direction of the University of Stuttgart. The Helmholtz Association of German Research Centres (Helmholtz-Gemeinschaft Deutscher Forschungszentren; HGF) is supporting the 'Research into transient phenomena and interactions during high-speed stalls' research group by funding access to the European Transonic Wind Tunnel (ETW). As an industrial partner, Airbus is providing a model as a test vehicle for wind tunnel experiments. The German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) brokered this cooperation and is supporting its progress by acting as a bridge between the scientific research and technological applications. It is also making available optical measurement systems that are globally unique in order to be able to carry out experimental investigations at the ETW. Thanks to this new alliance, scientists from several German aeronautical research groups and at DLR now, for the first time, have extensive opportunities to analyse the phenomena of stalls at high speeds and under realistic flight conditions in detail. This scientifically demanding project, which has total funding of approximately 6.7 million euro over three years, will contribute towards more efficient designs for future wide-bodied aircraft, thus making them lighter and more environmentally friendly.
"Given its expertise and experience of operating large-scale research facilities, DLR is a key interface for German aeronautics research," says Rolf Henke, DLR Executive Board Member for Aeronautics Research. "Thanks to DLR’s aeronautics research programme, we are in a position to bring the work of various different interest groups together, especially fundamental research and the subsequent users of its scientific findings, namely industry. Our work on climate-friendly aviation will only prove successful if we can manage to bring together all of the stakeholders."
One area of focus for the research group is what is referred to as a high-speed stall, a transition region at high transonic flight speeds in which the airflow separates and the wing begins to undergo strong vibrations. As an aircraft approaches the sound barrier, supersonic areas with shock waves form on the wing and around the engines, radically changing the aerodynamic properties and limiting the range of speeds that can be flown. A stall can easily occur behind the compression shock. The researchers are looking to investigate the stall and its consequences in detail using flow field measurements and computer simulations. A better understanding of the physical phenomena is an essential prerequisite for developing lighter and more economical wings.
Realistic wind tunnel tests are absolutely indispensable in order to be able to answer such scientifically demanding and application-relevant questions. The European Transonic Wind Tunnel is one of only two facilities in the world to offer an opportunity to study the physical mechanisms that occur on large aircraft during actual flight, under controlled conditions on the ground.