Flashback and Thermoacoustic Instabilities in Hydrogen/Ammonia Flames

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Carbon-free fuels, such as hydrogen (H2) and ammonia (NH3) can be produced from renewable energy, holding vast potential to develop carbon-free combustion technology and ensure a secure energy supply. Significant differences in the characteristics of the two fuels compared with traditional hydrocarbons present numerous challenges for their application, including issues that hinder the safe and flexible operation of power plants which use gas turbines. However, these challenges can be mitigated through fuel blending. The present proposal will focus on safety related issues, i.e., flashback (FB) and thermoacoustic instability, of aerodynamically stabilized H2/NH3 flames in a novel fully optically-accessible model trapped vortex stabilized combustor. The proposal will address three scientific questions: i) Can the important physical mechanisms underlying FB and thermoacoustic instability be better understood, and can quantitatively predictive FB models be developed? ii) Can the interaction between FB and thermoacoustic instability, which are important in gas turbines operating with hydrogen blends, be characterized, and predictive FB models extended to account additionally for the presence of inlet flow oscillations? iii) Can advanced diagnostics that enable time-resolved three-dimensional (3D+t) measurements be applied to closely confined flames in order to fully understand these inherently unsteady 3D processes? Multidisciplinary knowledge, including combustion science, acoustics, fluid dynamics, optical diagnostics, computational tomography, and signal processing will be employed to address these three questions. After addressing these, we will better understand how flashback occurs, aiding the development of H2/NH3 co-firing technology. Ultimately, this will allow us to develop the next generation of reliable and fuel flexible gas turbines, contributing to Europe’s leading position in the global energy transition.