Thermal regime of the vapor-state combustion of a magnesium particle

Altman, Igor; Vovchuk, Ya. I.

doi:10.1007/bf02699365

Cited by 11 publications

(7 citation statements)

References 1 publication

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“…Generalizing the Mg result [41], we can claim that the vapor‐phase combustion of Al is not possible without a partial condensation of gaseous alumina on the surface of a burning particle. Moreover, due to a possibility of the reaction Eq.…”

Section: Energy Balance and Regimes Of Combustionmentioning

confidence: 62%

“…The energy excess is, however, apparent since a significant part of condensation energy releases via light emission due to condense‐luminescence [11], and the corresponding energy is lost in the energy balance. As a result, the energy balance requires partial condensation of magnesia vapor on the surface of the burning Mg particle to sustain the process [41].…”

Section: Energy Balance and Regimes Of Combustionmentioning

confidence: 99%

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Comprehending Metal Particle Combustion: a Path Forward

Altman

Pantoya

2022

Propellants Explo Pyrotec

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The paper discusses the physics required for accurate modeling of metal particle combustion and includes aspects previously neglected. Specifically, three physical phenomena are emphasized: 1) internal boiling on the condensed oxide-metal interface; 2) condense-luminescent loss during nano-oxide formation; and, 3) suppressed heat transfer on the metal particle surface due to a low energy accommodation coefficient (EAC) are essential. The last two phenomena were explored in previous work. Internal particle interface boiling detailed in the current work enables the semi-heterogeneous combustion of Al particles, an im-portant process needing attention for accurate modeling. The interface boiling mechanism allowing for the semi-heterogeneous combustion explains a number of experimental puzzles related to metal particle combustion. In particular, the semi-heterogeneous combustion justifies the coexistence of two burning regimes of Al particles (slow and fast) recently observed. Based on reported findings, revising current numerical models for metal particle combustion to include these three physical phenomena is necessary. Implications toward enhancement of energetic performance for metal-containing formulations are also discussed.

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Section: Energy Balance and Regimes Of Combustionmentioning

confidence: 62%

Section: Energy Balance and Regimes Of Combustionmentioning

confidence: 99%

Comprehending Metal Particle Combustion: a Path Forward

Altman

Pantoya

2022

Propellants Explo Pyrotec

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“…The appearance of both nano-and micro-sized particles aligns with the current understanding of vapor-phase combustion of a metal particle [5] [6]. Speci cally, alumina nanoparticles form in the envelope surrounding the burning particle and microparticles result from the formation of an oxide residue that is an essential condition to sustain combustion [20]. Metastable alumina phases are associated with nanoparticle growth because nanoparticle formation involves rapid particle cooling that inherently induces structural defects [21] that result in formation of the metastable phase, i.e., γ-alumina.…”

Section: A Sem Analysismentioning

confidence: 74%

Direct Identification of Two Regimes of Metal Particle Combustion using Condense-luminescence

Tran¹,

Pantoya²,

Altman³

2021

Preprint

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Experiments were designed to investigate two regimes of metal particle combustion: fast and slow burning regimes. Stress-altering aluminum particles had been shown to produce a distinctly faster burning rate compared to untreated aluminum particles. The root cause for the differences in burning rate had been unclear. In this study, stress-altered and untreated aluminum particles were reacted as dispersed powder in a closed bomb calorimeter designed to monitor the transient temperature changes resulting from energy release upon combustion. The product residue was analyzed for size and species concentration. Results showed metastable γ-alumina that is associated with nano-oxide formation was in substantially higher concentration for stress-altered particle reactions that produced greater energy transfer rates. The increased energy transfer rate corresponded to higher radiant energy emission owing to condensation of nano-oxide particles. This study justifies condense-luminescence as a means for increasing the energy release rate of aluminum particles. By strategically altering metal fuels to control a formation of nano-oxide particles upon combustion, appreciable increases in the radiant energy flux can transform energy release rates.

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“…This leads to the edge smoothening and the spheroidization of cubic particles. It should be noted that this concept is in line with the temperature estimate of ~2600 K, corresponding to an Mg particle combustion [ 11 ] that is well below the magnesia melting point of about 3100 K. Since both growing (hot) and grown (cold) particles coexist in the flame [ 12 , 13 ], the pyrometry temperature measurements in the system of question would not be representative. In addition, it must be emphasized that, regardless of the size, no particles with a rounded shape are seen in both scenarios: unaffected flame and that exposed to positive ions.…”

Section: Resultsmentioning

confidence: 99%

Effect of External Charging on Nanoparticle Formation in a Flame

2021

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This paper attempts to demonstrate the importance of the nanoparticle charge in the synthesis flame, for the mechanism of their evolution during formation processes. An investigation was made of MgO nanoparticles formed during combustion of magnesium particles. The cubic shape of nanoparticles in an unaffected flame allows for direct interpretation of results on the external flame charging, using a continuous unipolar emission of ions. It was found that the emission of negative ions applied to the flame strongly affects the nanoparticle shape, while the positive ions do not lead to any noticeable change. The demonstrated effect emphasizes the need to take into account all of the phenomena responsible for the particle charge when modeling the nanoparticle formation in flames.

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Thermal regime of the vapor-state combustion of a magnesium particle

Cited by 11 publications

References 1 publication

Comprehending Metal Particle Combustion: a Path Forward

Comprehending Metal Particle Combustion: a Path Forward

Direct Identification of Two Regimes of Metal Particle Combustion using Condense-luminescence

Effect of External Charging on Nanoparticle Formation in a Flame

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