Study on the flame structure and combustion dynamics of ammonia swirl flame assisted by gliding arc plasma

Ammonia, as a hydrogen storage medium with high stability, is expected to play an important role in the future zero-carbon energy system. However, when used as a zero-carbon fuel, ammonia faces challenges such as low flame speed and poor stability in combustion applications. Plasma-assisted combustion is a promising technical means to achieve efficient, stable, and clean combustion of ammonia. In this study, gliding arc plasma-assisted combustion technology is adopted to optimize the ammonia combustion through its highly active particles and local high temperature. Through high-speed imaging diagnosis combined with time-domain analysis methods, the influence mechanism and effect of plasma on the stability of ammonia flames are explored. The research results show that the presence of gliding arc effectively promotes the reaction rate at the shear layer of the flame, thereby significantly reducing the combustion oscillations outside the recirculation zone, thus effectively enhancing the flame stability. Meanwhile, under low equivalence ratios or high air flow rate, effective combustion stabilization can be achieved, with a plasma power consumption of less than 1% of the flame power, the presence of gliding arc significantly improves the reaction rate at the flame root, narrows its oscillation range, which may be an important mechanism for gliding arc to broaden the lean combustion limit of ammonia. Gliding arc significantly enhances the stability of flame by improving the time-domain and spatial oscillation characteristics of ammonia combustion, providing a theoretical basis and technical support for ammonia in important application fields such as gas turbines and industrial burners. • Gliding arc significantly improves flame stability at low EQR and high flame power. • Gliding arc greatly refines the spatial distribution of TDU and PSD in NH3 flame. • Higher input voltage does not yield a more significant flame stabilization effect. • As flame power≈7kW, plasma power consumption <1% is enough for flame stabilization.