In order to achieve the greening of the European air transport with the deployment of low emission and low noise propulsion systems the reduction of core noise plays an important role. The ability to design low core noise aero-engines requires the development of reliable prediction tools. This development demands extensive research with dedicated experimental test cases and sophisticated numerical and analytical modelling work to broaden the physical understanding of core noise generation mechanisms.
This objective is only reachable with an extensive cooperation on the European level. In the Research on Core Noise Reduction (RECORD) project the major aero-engine manufacturers of five different European countries collaborate in order to enable the design of low core noise aero-engines.
In RECORD the fundamental understanding of core noise generation and how can it be reduced will be achieved by combining the research competence of all European experts in universities and research organizations working in this field of core noise. This concept of the RECORD project is completed by the technology development of small and medium size enterprises distributed in Europe.
RECORD will promote the understanding of noise generating mechanism and its propagation taking the interaction of combustor and turbine into account. The importance of direct and indirect noise will be quantified. Through carefully designed experiments and extensive numerical calculations, the numerical methods and assumptions will be validated and extended. As a result, low-order models will provide a quick approach for the noise design of combustors and subsequent turbine stages while the more time-consuming and expensive LES calculation will provide a more detailed picture of the flow physics. Finally, RECORD will develop means and methods for core noise reduction.
Quieter aircraft core engines
EU-funded researchers are devoting extensive research to improve understanding and reducing of combustion noise and its sources in aircraft engines.
Reduction of aero engine emissions and noise plays an important role in Europe's target for a greener air transport system. Combustion noise is a potential major contributor to the overall noise emitted by low-emission engines. This accounts for the increased interest in development of reliable noise prediction tools for modern aero engines.
The EU-funded project 'Research on core noise reduction' (RECORD) is enhancing understanding of core noise-generating mechanisms and its propagation, also taking combustor-turbine interaction into account. An important focus will be on the direct and indirect combustion noise mechanisms.
RECORD is using diverse prediction methods for core noise, ranging from low-order modelling approaches to high-fidelity compressible large eddy simulations. The former will help with low-noise designs of combustors and subsequent turbine stages, while the latter will provide a more detailed picture of flow fields.
Through carefully designed experiments and extensive numerical calculations, these methods will be validated and extended.
Scientists have drafted all relevant specifications with the aim of defining three test cases: The prediction methods for entropy and vorticity noises in transonic nozzles are currently being validated using the Nozzle Test Case.
Within the Combustor Test Case the combustion chamber has been modified with a thermally stabilised, water-cooled casing. The experimental tests of this new set-up are ongoing. Scientists made good progress concerning the numerical simulations.
Extensive test rig modifications in the Turbine Test Case have been achieved to enable a detailed analysis of sound transmission through a turbine stage and sound generation by inflow disturbances. A numerical benchmark test of the undisturbed turbine flow test has allowed comparison of the different applied numerical methods.
Through better understanding of this complex noise sources, RECORD should be able to provide designs for reduced noise of relevant components such as combustors and turbines.
RECORD should also provide tools that will allow trade-offs between noise and emissions and allow the development of low-noise technologies. Its objectives are in line with the Advisory Council for Aeronautics Research in Europe's (ACARE) Vision 2020 for reducing the perceived noise by 50 %.