CompLex thErmoAcoustic iNteraction mEchanisms in spRay Flames in Low-nox Annular coMbustion chambErS

ended

This project is focused on the fundamental problem of combustion dynamics that has many practical implications. It specifically considers annular systems like those used in land based gas turbines and aeroengines. The corresponding combustors feature new architectures that reduce pollutant NOx emissions to comply with increasingly stringent regulations. However, these new designs and the essentially lean premixed mode they employ also promote a resonant coupling between combustion and acoustic modes. These combustion instabilities have many detrimental effects leading in extreme cases to mechanical failure. Despite the large number of investigations concerning instabilities arising with premixed flames yet few are the studies dealing with cases where the fuel is injected as a spray. Furthermore, the limited availability of engine data is a further obstacle for these studies in a real combustor. The present project aims to fill this gap of knowledge by proposing combined numerical and experimental investigations on spray flame dynamics and spray flame coupling with azimuthal modes in annular systems. The project first focuses on the analysis of the nonlinear response of a single spray flame to incoming acoustic perturbations via Large Eddy Simulations. The study is then extended to a multiple swirl spray injector injector system to investigate the impact on the flame response of the interaction between multiple adjacent flames. Numerical results are compared with experiments carried out in unique facilities available at EM2C Laboratory including the annular MICCA-Spray combustor. Theoretical and numerical procedures involving advanced coupling of the combustor acoustics with the obtained flame responses are developed to predict the limit cycles observed during experiments. Finally, the combustion dynamics observed experimentally in a Safran Aircraft Engine combustor will be investigated to verify the transferability of the developed techniques to a full-scale system.