A systematic review of enhancing stabilization performance and mitigating thermoacoustic instability in renewable ammonia turbulent combustion

Ammonia, as a carbon-free and hydrogen energy carrier, is receiving emerging interest to mitigate anthropogenic carbon dioxide emissions from power generating systems and aviation propulsion sectors. While ammonia combustion is a theoretically feasible alternative to tackle greenhouse gas issues, the realization of such a renewable fuel in large-scale combustion systems requires an understanding of turbulent flame dynamics and stability in consideration of the poor combustion characteristics such as the low laminar burning velocity and high ignition energy. This paper reviews the recent advances and developments of ammonia turbulent combustion that contribute to providing insight into the combustion fundamentals and guiding combustor design for practical applications. The fundamental characteristics of ammonia turbulent flames are first introduced. This is followed by a detailed discussion concerning the stabilization enhancement strategies of ammonia turbulent flames, along with the underlying physical/chemical mechanisms. Furthermore, the dynamical thermoacoustic instability of ammonia flames possibly occurring within gas turbine engines is characterized, with the emphasis being placed on the generation mechanisms and mitigation means. Finally, this paper concludes with future research directions and perspectives.