Research on Core Noise Reduction
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, the noise related to the combustion system, 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 RECORD the major aero-engine manufacturers of five different European countries collaborate to enable the design of low core noise aero-engines. Within RECORD the fundamental understanding of how core noise is generated 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.
For the reduction of core noise in prospective aero-engine generations the RECORD project pursues two main objectives:
1. The improvement and validation of core noise modelling and prediction methods through carefully specified experimental means concerning: the generation of direct combustion noise, the generation of indirect combustion noise, and the transmission of combustion noise through a turbine
2. The development and testing of core noise reduction methods
Previous national research and development activities in the fields of unsteady combustion phenomena and turbine noise generation revealed the need for a project integrating aspects in different dimensions. In the concept of the RECORD project, the connection of all these aspects is mapped in the line of “RECORD builds bridges”.
First of all from the technological dimension the RECORD project considers the interaction between two different components of aero-engines. As other projects – in
the past or still on-going – focus on noise generation mechanisms and noise reduction of single components of an aero-engine (PROBAND, RESOUND, COJEN, FLOCON, …), RECORD emphasizes the coupling effects between the combustion chamber and the turbine, the sources of indirect noise.
In RECORD the different stages of scientific knowledge development will be coupled and extended. The foundation is the understanding of core noise generation and transmission mechanisms. In further steps the modelling and the prediction will be refined, enhanced and validated. Finally potential strategies for core noise reduction concerning the direct and the indirect combustion noise will be developed, tested and evaluated.
Within RECORD an integrated approach will be pursued in order to thoroughly understand direct and indirect noise sources from the combustor and their interaction with the turbine. Various numerical models from state-of-the-art LES simulations to low-order physical models will be applied to the inhomogeneous reacting flow in a combustion chamber in order to identify sources for direct and indirect noise. Most of these methods are developed by combustion specialists, and some of them will be used with a focus on acoustics for the first time.
Dedicated experiments will be performed in order to validate the results of these numerical tools and enable further development of the tools based on the new data. The advanced prediction tools will in turn be used for full scale combustion noise calculations. Finally, the assessment of the achievements of RECORD will be made by the comparison of these full-scale combustion noise calculations with existing real engine data obtained outside the proposed project.