At the 'core' of aircraft noise – new findings for quieter engines
January 22, 2016
At the 'core' of aircraft noise – new findings for quieter engines
The tested turbine stage
In the turbine, the energy of the hot combustion gases is converted into power to propel the aircraft. This is one point of origin for what is referred to as ‘core noise’, one of the noise sources studied in RECORD.
Image: 1/4, Credit:
Laboratorio di Fluidodinamica delle Macchine der Politecnico di Milano.
Simulation of the combustion chamber-turbine interaction
The interaction between combustion chambers and turbines through fluid mechanics and acoustics and the resulting noise are the specific focus of the RECORD project.
Flow simulation of the combustion chamber test case in RECORD
The reliable numerical prediction of the flow and noise field of combustion chamber-turbine systems is essential for the development of quieter aircraft engines.
Image: 4/4, Credit:
Lehrstuhl für Thermodynamik der Technischen Universität München.
Aviation in Europe needs to become more environmentally friendly and quieter. To get to the 'core' of aircraft noise on the ground, researchers at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) dismantled current aircraft engines and began conducting physical modelling. In extensive tests, the researchers started looking for answers to a number of questions. How and where exactly does the noise in aircraft engines generate? How do the noise sources change when modifications are made to engine components? The result is a new model for the design of quieter engines.
Tracking down the noise
The causes of aircraft noise vary greatly. Where the noise is created and how it can be reduced has been occupying engineers and scientists ever since there were aircraft with gas turbines. "We are particularly interested in the processes that occur between the turbine and the combustion chamber," explains Friedrich Bake from the DLR Institute of Propulsion Technology. "For this reason, we have designed several experiments and tested them on the most appropriate test rigs –min this country and abroad." The engine acoustics researchers succeeded for the first time in determining the physics behind what is referred to as 'core noise' and represented it in a numerical model.
The processes involved in the generation of core engine noise can be accurately demonstrated with the model they have developed. This not only gives rise to a general understanding of noise generation, but also enables the design of quieter and more environment-friendly engines. The model has been validated during specifically designed tests at various research locations in Europe. "The test results are available to the global research community in a database," explains Bake. "So our research can also be used in new projects and application studies."
