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ISSN Печать: 2150-766X
ISSN Онлайн: 2150-7678
Indexed in
INVESTIGATION OF BORON IGNITION AND COMBUSTION BY MEANS OF FAST CINESPECTROGRAPHY
Краткое описание
Boron ignition and combustion were investigated in oxygen-argon mixtures of different component concentration over a wide range of pressures ( 0.1...10 MPa ). In a visible region radiation spectra of the specimen surface are obtained and that of flame around it with time resolution up to 20 ms. An original method of color-luminance pyrometry has been applied to measure surface temperature. The experiments based on suggested technique illustrate the existence of three regimes of boron conversion into reaction products: high-temperature oxidation, surface combustion, and gas-phase combustion. It was found that the transition to gas-phase combustion occurs at specimen surface temperatures considerebly lower (in conditions close to atmospheric ones, by -550 K ) the boiling point of B2O3. A non-trivial character of ignition induction time versus oxygen content in the mixture was also discovered. The concept of a finite minimum thickness of the oxide layer is suggested to explain this facts. Under the conditions of regulated specimen heating from its initial temperature pressure increasing in moderate limits causes significant rise in ignition time and decrease in gas-phase combustion time. The latter manifests itself much more strongly than may be expected from the combustion diffusion model. At high pressures (≥5MPa) the process in oxygen - containing oxidative mixtures corresponds with either ineffective surface combustion or even its absence.
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Savel’ev A. M., Titova N. S., Computational and Theoretical Analysis of the Effect of an Aluminum Borate Oxide Film on the Ignition Conditions of Single Aluminum Diboride Particles, Combustion, Explosion, and Shock Waves, 57, 3, 2021. Crossref