German researchers are studying how noise is created in aircraft engines using lasers and microphones to design quieter aircraft in the future.
The project organised by the German Aerospace Centre (DLR) will run a series of tests using the Centre’s Airbus A320 aircraft in the Lufthansa Technik soundproof hangar at Hamburg Airport.
Being the first of its kind, the study relies on contactless laser metrology to uncover the sources of noise inside jet engines and the main fan.
"What we have planned in Hamburg is globally unique," said Andreas Schroeder from the DLR Institute of Aerodynamics and Flow Technology. "We want to locate the zones within the engine where large, turbulent fluctuations in velocity and density produce noise," he said.
The team will mount microphones near the intake and exhaust areas of the engines and will try to match the recorded noise levels with visualisations of flow based on laser light.
The project, named SAMURAI (Synergy of Advanced Measurement techniques for Unsteady and high Reynolds number Aerodynamic Investigations) is a multidisciplinary venture bringing together researchers from several DLR-related institutions.
"If our measurements help us acquire a better understanding of where noise is produced within an engine, we will be able to develop improved computer simulations of engine noise generation. In the long term, digital design processes will yield substantially quieter engines," Andreas Schroeder said about the goals of the project.
The team hopes to deliver improved simulations of jet engines and their noise-producing flow structures by mid-2014.
The Airbus A320 used for the study is specifically adjusted for research proposes and used regularly by the DLR for various projects. "This medium-range passenger aircraft, refitted as an airborne test centre, is an ideal and representative research object for scientists, particularly as it is fitted with V2500 series engines, which are found throughout the world on thousands of aeroplanes and were developed in a cooperation between MTU, Pratt &Whitney, Rolls Royce and Japanese Aero Engines Corporation," said Oliver Brieger, Head of Flight Operations at the DLR Flight Experiments Facility, which is responsible for operating the aircraft.
The soundproof hangar where the tests will be conducted was opened in 2002. The 95 by 92 metres building is equipped with technology for advanced measurements and used regularly for jet-engine testing. Large enough to accomodate a super-jumbo, the hangar enables performing engine testing without disturbing residents of nearby towns.