Aircraft engine noise is a socially pressing issue with a wide range of causes. Until now, turbulent fluctuations in the exhaust gas stream have not been fully understood as one of the major sources of noise. Researchers at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) have now managed to make these turbulent flow structures in the engine exhaust gases visible using imaging laser measurement technology, and they have measured the overall flow behind the engine with unprecedented quality. Future generations of engines will be able to benefit from this new knowledge.
Seventy-five years ago, flow researchers at the Aerodynamic Research Institute (Aerodynamischen Versuchsanstalt; AVA) in Göttingen unveiled a car that, for many years, was considered the quintessential execution of aerodynamic design in vehicle construction; its name was the Schlörwagen. A large number of myths have arisen about what became of the vehicle. Now the archives at the German Aerospace Center (DLR) – the successor to AVA – have helped shed light on some of the mysteries.
Scientists at DLR Göttingen have achieved a world first – showing the deformation of an aircraft propeller blade during flight. They have developed a special camera that can resist the enormous forces exerted during rotation.
To fly once around the world, across continents and oceans – powered by the Sun; this is the unprecedented goal of the Solar Impulse project. The flying venture is expected to take place in 2015, using an extremely lightweight aircraft covered with solar cells and powered by four electrically driven propellers.
Slower landing approaches by aircraft lead to less noise. How slow, steep and hence quiet a modern commercial aircraft can arrive at a destination airport is determined by the performance of the high-lift system with its retractable slats and flaps on the wings. Another advantage of reduced landing speeds is that shorter runways can be used. The German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) has joined with Airbus, and the European Transonic Wind Tunnel (ETW) in the three-part project HINVA (High lift INflight VAlidation), consisting of wind tunnel experiments, flight tests and computer simulations. The aim is to combine computer models and wind tunnel tests to substantially improve predictions of high-lift performance and hence pave the way for slower and quieter approach flights. In early February, the project performed unique wind tunnel experiments at cryogenic temperatures in the ETW in Cologne. Equipped with laser measurement technology and other advanced measurement systems, the researchers achieved hitherto unknown precision in detecting the flowfield around an Airbus A320 with extended landing flaps and slats under flight-representative conditions. The researchers had constructed a high precision wind tunnel model specifically for the tests, based on flow measurements performed during in-flight tests with the DLR A320 ATRA research aircraft.
Researchers from DLR based at Göttingen and Braunschweig have succeeded for the first time in visualising the main cause of what makes helicopters so noisy while in the air.
The sound of aircraft engines starting up – an everyday occurrence in many towns close to airports. To help develop quieter aircraft engines, scientists from DLR are going to use contactless laser metrology and microphones for the very first time to investigate the sources of noise inside jet engines and on the main fan.
Holger Hennings was one of the first people to show an interest in wind power. He followed the failure of the large Growian science project and saw how wind power turbines went on to become a surprising success. Today, Hennings works at the DLR site in Göttingen, making wind power turbines safer and more efficient to operate.
Researchers at the German Aerospace Center (DLR) in Göttingen have discovered a way to make helicopters more manoeuvrable.
Insects are capable of masterful feats of flying; whenever they witness locusts flying long distances or moths hovering over flowers, aerodynamicists can only marvel.