@article{XIE2026, 
author = {Dingjiang XIE and Yong TANG and Kuanyu WANG and Qing CAO and Baolu SHI and Majie ZHAO and Ningfei WANG},
title = {Flame stabilization and pollutant reduction of NH3/Air premixed flame with ethanol spray in a tangential swirl combustor},
year = {2026},
journal = {Chinese Journal of Aeronautics},
volume = {39},
number = {4},
keywords = {Ammonia, Blending combustion, Ethanol, Lean extinction limit, Pollutant emissions, Tubular swirl flame},
url = {https://www.sciopen.com/article/10.1016/j.cja.2025.103896},
doi = {10.1016/j.cja.2025.103896},
abstract = {This work aims to establish a stable premixed ammonia/air flame in a tangential swirl combustor by employing an ethanol spray to extend the fuel-lean extinction limit of the ammonia flame and reduce pollutant emissions. A Planar Laser Induced Fluorescence (PLIF) system is introduced to acquire the flame structure of this blending system. The results demonstrate that OH radicals originating from the ethanol flame support the ammonia flame, in which fluorescence images are indicated by the NH2 radicals. Moreover, the lean extinction limit is significantly extended from an equivalence ratio of 0.6 to 0.1. In particular, the addition of a minor quantity of ethanol (3 mL/min) to ammonia flame sustains the blending flame due to the ultralow extinction limit of the ethanol swirl spray flame. However, both experimental data and chemical reaction analysis reveal that an increase in OH radical concentration leads to an elevation in NOx (nitrogen oxides) concentration. This poses a challenge in balancing the effects of ammonia consumption and NOx generation in the blending combustion system. Ethanol flames indeed generate active radicals (O, OH, HO2, etc.) to accelerate ammonia oxidation. However, these active radicals also exacerbate the reaction between NO and NO2, inhibiting their conversion to N2. Even so, the objective of achieving clean combustion with low concentrations of both NOx and unburned NH3 can still be met under the condition of the total air flow rate 90 L/min and the global equivalence ratio 0.7.}
}