TORCH · ThermoacOustic instabilities contRol in sequential Combustion cHambers

A new type of combustor architecture for large gas turbines has emerged in recent years: sequential combustion systems operated at constant pressure. This major technology change results from the need for more operationally and fuel flexible gas turbines, for future sustainable energy networks. As for regular gas turbines, the risk of combustor breakdown due to thermoacoustic instabilities is a major challenge. While the harmful consequences of these instabilities in novel sequential combustors can be as dramatic as in conventional systems, the associated physics is considerably complexified, because the two flames not only “talk” together via sound waves, but also via entropy waves. Our aim is to propose, investigate and develop novel active and passive control technologies, tailored for this new generation of combustors, in order to suppress their thermoacoustic instabilities. It brings significant scientific challenges in fluid mechanics, acoustics, combustion, nonlinear dynamics and control theory. We will address the problem of controlling these instabilities on two unexplored fronts: First, we intend to significantly move forward the state-of-the-art in passive control of combustion instabilities, by creating acoustic metamaterials with unprecedented acoustic damping properties, and capable of long term operation in harsh environments. Second, we plan to address scientific challenges, required to successfully achieve active combustion control in sequential combustors, by distributing non-equilibrium plasma discharges to locally and dynamically enhance the autoignition chemistry. To achieve these ambitious goals, a combination of experimental, numerical and theoretical methods will be applied with the aim to ultimately establish the potential and limitations of these novel technologies. This research deals with new areas in the field of thermoacoustics, and builds upon the PI’s scientific expertise in combustion and acoustics and on his technological know-how.