Morphological and nanostructural characteristics of aircraft-emitted soot particles during taxiing condition: A...

Soot particles emitted by aircraft during taxiing are significant anthropogenic pollutants around airports, posing substantial risks to local environment and public health. Therefore, understanding the emission characteristics and factors influencing soot particle formation during taxiing is crucial for environmental protection around airports. This study investigated the emission characteristics, microscopic morphology, and nanostructural features of soot particles during taxiing, based on the Twin Annular Premixing Swirler (TAPS) combustor, which is widely employed in modern aero-engines. The characteristics of particles emitted during taxiing were compared with those emitted during cruising, and the influence of the pilot-stage equivalence ratio on soot emissions during taxiing was also examined. The results indicate that during taxiing, as equivalence ratio rises from 1.18 to 1.63, the concentration of soot particles increases from 1.8 × 10⁶ to 1.1 × 10⁷ n/cc, far exceeding the cruising levels of 1.9 × 10⁴ n/cc. Meanwhile, the particle size increases from 20-50 nm to 80-120 nm, and the proportion of embedded soot rises from 70 % to 90 %. Furthermore, the soot particles emitted during taxiing exhibit longer fringe lengths, more disordered graphite layers, greater thickness, and weaker oxidative activity. These findings suggest that particles emitted during taxiing have a longer atmospheric residence time, thereby posing a more severe environmental threat. Additionally, the concentration and size of soot particles during taxiing are positively correlated with the pilot-stage equivalence ratio, while the graphite layer thickness shows a negative correlation with the equivalence ratio.