@article{0f1e4631-b60a-4337-a54a-1f59028fa03a,
  abstract     = {{We report a comprehensive characterization of the multi-layered flame structure of a burning aluminum (Al) droplet in steam, using a novel spatiotemporally resolved laser absorption imaging technique combined with detailed numerical simulations. Spatial distributions of Al vapor mole fraction in the near-surface region (r/R0 < 1.2, R0: droplet radius) are quantified by accounting for resonance broadening due to Al-Al atomic collisions. Al vapor distribution reaches a steady state about 13 ms after ignition, starting at ∼0.7 mole fraction near the surface and declining rapidly to ∼0.02 at r/R₀ ≈ 1.4, and reaching ∼4 × 10⁻⁶ at r/R₀ ≈ 8. Numerical simulations incorporating detailed chemistry are conducted to investigate the detailed combustion process under experimental conditions. Combining experimental and simulated profiles of Al(g), AlO(g), AlH(g), and Al₂O₃(l), an in-depth analysis of the species profiles, reaction pathways, and flow field elucidates the multi-layer flame structure and flow transport-chemistry interactions. Key findings include: (1) H-chemistry plays a significant role in the near-surface region (r/R₀ < 1.2). AlH formation via H+Al+M→AlH+M is primarily responsible for Al depletion and heat release in this region. (2) The AlO peak is correlated with the Al₂O₃ peak in both experiments and simulations. Reaction pathway analysis confirms AlO as the major precursor to Al₂O₃ formation, predominantly through the AlO→AlOAlO→Al₂O₃(l) pathway. (3) The axisymmetric distribution of Al vapor and asymmetric alumina clouds reveal the interaction of Al vapor Stefan flow against H and H2 diffusion in the near-surface region and the surrounding co-flow in outer region. These results provide new quantitative insights to advance the fundamental understanding of Al/steam combustion.}},
  author       = {{Wu, Zhiyong and Wang, Weitian and Qiu, Yue and Zhou, Yuchen and Ruan, Can and Bai, Xue-Song and Alden, Marcus and Li, Zhongshan}},
  issn         = {{1540-7489}},
  keywords     = {{Aluminum combustion; Laser absorption imaging; Flame structure; Gas-phase intermediate species}},
  language     = {{eng}},
  month        = {{07}},
  pages        = {{106218--106218}},
  publisher    = {{Elsevier}},
  series       = {{Proceedings of the Combustion Institute}},
  title        = {{Flame structure of micron-sized burning aluminum droplet visualized by high-speed quantitative laser absorption imaging of Al, AlO, and AlH}},
  url          = {{http://dx.doi.org/10.1016/j.proci.2026.106218}},
  doi          = {{10.1016/j.proci.2026.106218}},
  volume       = {{42}},
  year         = {{2026}},
}