Effect of oxygen staging on particle temperature and velocity in turbulent iron dust flames

Iron powder has emerged as a promising carbon-free energy carrier due to its high energy density, global availability, and potential for closed-loop recycling. While single-particle combustion has been extensively investigated, considerably less is known about particle dynamics and temperature evolution in turbulent, application-relevant iron dust flames. In the present work, spatially resolved particle velocity fields and two-dimensional particle temperature distributions are measured in a turbulent, methane-assisted iron dust flame using planar particle image velocimetry and color-camera pyrometry. Experiments are conducted in an optically accessible laboratory-scale combustor with systematically varied oxygen staging. Increasing the overall oxygen availability significantly modifies the near-burner flow structure and enhances particle temperatures, leading to extended flame lengths and mean particle temperatures exceeding 2100 K. In contrast, supplying additional oxygen at a later combustion stage primarily sustains downstream particle oxidation while leaving the near-burner temperature field largely unaffected. These results demonstrate that oxygen staging in combination with turbulent mixing strongly influences heterogeneous particle oxidation. The combined diagnostics provide quantitative insight into the interaction between flow structure and thermal particle behavior in dense iron dust flames and deliver a comprehensive experimental dataset for validation of numerical models of turbulent iron dust flames.