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International Journal of Energetic Materials and Chemical Propulsion
ESCI SJR: 0.142 SNIP: 0.16 CiteScore™: 0.29

ISSN Imprimir: 2150-766X
ISSN On-line: 2150-7678

International Journal of Energetic Materials and Chemical Propulsion

DOI: 10.1615/IntJEnergeticMaterialsChemProp.v2.i1-6.280
pages 455-468

THE IGNITION AND COMBUSTION OF BORON DUST SYSTEMS

A. N. Zolotko
Department of Physics, I. I. Mechnikov Odessa National University, Ukraine

RESUMO

Experimental and theoretical studies of the boron ignition and combustion in the dry oxygen-containing medium for the various disperse system were carried out. Analysis of the ignition regimes was realized in supposition that two-stage process takes place on the surface of boron particles. The first stage is exothermic reaction which runs with accumulation of the product (B2O3) which slows the further process. The second stage is endothermic reaction but it goes with the removing of the product (for boron it is B2O3). These two stages are correlated but the ignition mechanism may be alternative: either as a result of action of the both stages, as it considered, or a result of action the first stage only. Accordingly, for the various ignition mechanisms different dependences of the ignition temperature and delay time on parameters of the system and ambient were observed. Critical conditions and ignition delay time for the both mechanisms were presented in analytical form. Comparison of theoretical and experimental data was carried out for the dust clouds.
The quasi-steady problem of boron dust clouds bulk combustion has been solved. This problem takes account of two specific factors. It is the slowing-down action of the oxidizer depletion and intensification of the process by the self-heating of the dust cloud. Analytical expression for the dust cloud combustion time was obtained for the isothermic case. It is shown that for the diffusion combustion regime the role of the self-heating factor is small, the oxidizer depletion slows the process of particle burning in dust clouds as compared with the burning of the single particle. For kinetic combustion regime a self-heating of the dust cloud compensate the role of the oxidizer depletion and accelerate the process as compared with the burning of the single particle. The experimental data presented in this work confirm the theory.


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