The propulsion of the majority of commercial aircraft relies on turbofan engines. The current trend for future turbofan engines is towards even higher bypass ratios. These Ultra-High Bypass Ratio (UHBR) engines have large fans rotating at relatively low speeds. As a consequence of the lower speed, the fuel consumption can be reduced. Another consequence is that the engine noise signature is modified. While jet noise and fan noise will be reduced, core noise will be become more significant.
In this context, the CIRRUS project aims to validate advanced low noise concepts, by developing both advanced numerical and experimental tools, to reduce the core noise of future UHBR 2030+ turbofan engines.
The overall goals of CIRRUS are to:
- Improve numerical methods to predict the noise source mechanisms and the acoustic core noise radiation,
- Improve experimental methods to measure the contribution of core noise on real engines,
- Develop, test and integration of new generations of noise reduction acoustic liners made of Ceramic Matrix Composites (CMC),
- Investigate on future UHBR 2030+ architectures the influence on the core noise sources by comparing various configurations of turbines by reducing the number of stages.
The first stream of the project is dedicated to the improvement of the core noise prediction tools with the implementation of an industrial LES/CAA workflow. A second stream is focused on experimental activities with the development of post-processing methodologies to identify the core noise contribution. The third stream of the project is focused on low noise concepts. CMC liner concepts will be investigated and tested. Finally, the relevant low noise concepts will be evaluated on a full scale UHBR and a core noise experimental data base will be created by conducting acoustic test campaigns on realistic engines. A comparison between measurements and simulation results will be performed to qualify the numerical means up to TRL6.