Experimental characterization of combustion regimes for micron-sized aluminum powders

Abstract : This work presents an experimental study of combustion characteristics of micron-sized aluminum particles in the transition regime under constant volume combustion experiments. Burning velocities were estimated from the measured pressure traces using both a simpli fied model for aerosol combustion on closed spherical bombs and a semi-empirical correlation, and compared to previous literature. Flame temperatures were measured by bi-color pyrometry and indicate that for particles smaller than 12 m, the flame moves closer to the particle's surface, since flame temperatures were close to aluminum boiling point. For 17:9 µm particles, flame temperatures were close to predicted adiabatic flame temperature and alumina vaporization-dissociation temperature, indicating a classical vapor phase flame under a diffusion-controlled mechanism. However, spectroscopy measurements did not detect signifi cant reductions on molecular AlO emissions for ner particles. This indicates a still very signi ficant presence of vapor phase reaction for powders with a Sauter mean diameter at least as large as 7 µm, which is further supported by the presence of nanometric spheres in the combustion residues, since alumina formed under a vapor phase reaction is expected to condensate into nanometric droplets.
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https://hal.archives-ouvertes.fr/hal-02018393
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Submitted on : Wednesday, February 13, 2019 - 7:09:34 PM
Last modification on : Tuesday, November 19, 2019 - 4:46:47 PM

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Ricardo Lomba, Fabien Halter, Christian Chauveau, Stéphane Bernard, Philippe Gillard, et al.. Experimental characterization of combustion regimes for micron-sized aluminum powders. 53rd AIAA Aerospace Sciences Meeting, Jan 2015, Kissimmee, United States. ⟨10.2514/6.2015-0925⟩. ⟨hal-02018393⟩

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