Modeling of aluminum particle combustion with emphasis on the oxide effects and variable transport properties

Yang, Hyung Kook; Yoon, Woong

doi:10.1007/s12206-010-0209-7

Cited by 32 publications

(6 citation statements)

References 40 publications

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“…This was in agreement with our previous result that the three distinctive stages represented heating, melting and evaporation until ignition [6]. Yang et al [19] and Ermakov et al [20] have reported the three-stage phenomenon for micron-sized aluminum during ignition. Trunov et al [21] developed a simplified ignition model and assumed that ignition occurs when the particle temperature exceeds the alumina melting point.…”

Section: Resultssupporting

confidence: 93%

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Laser-Induced Ignition and Combustion of Individual Aluminum Particles Below 10 μm by Microscopic High-Speed Cinematography

Hou

Wang

2020

Processes

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Metal aluminum has been widely used as an ingredient in propellant, gunpowder and thermite, but there is less understanding of the combustion mechanism of aluminum particles from submicron to several microns in diameter. This paper proposes to experimentally investigate the ignition and combustion characteristics of individual aluminum particles below 10 μm. A specific in situ diagnostic experimental apparatus was first designed for directly observing the ignition and combustion behaviors of individual aluminum particles, with a submicrometer spatial resolution and a temporal resolution of tens of microseconds. Direct observation through microscopic high-speed cinematography demonstrated that, when heated by a continuous laser, individual aluminum particles thermally expanded, followed by shell rupture; the molten aluminum core overflowed and evaporated, leading to ignition and combustion. Further results showed that, when the laser power densities were gradually increased (5.88, 7.56 and 8.81 × 105 W/cm2), the durations of thermal expansion, melting and evaporation were shortened. The required time for the aluminum particles to expand to 150% of their initial diameter was shortened (34 s, 0.34 s and 0.0125 s, respectively). This study will be beneficial to further extend the investigation of other individual metal particles and reveal their combustion mechanism by direct observation.

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Section: Resultssupporting

confidence: 93%

“…The flame appeared as a weak yellow at 1.909 ms, and there was a bright yellow flame at the lower left corner of the particle (Figure 10c). This showed quasi-steady-state combustion [19]. At 2.546 ms, the aluminum particle was completely covered by a yellow flame owing to a heterogeneous oxidation reaction at the surface.…”

Section: Resultsmentioning

confidence: 91%

Laser-Induced Ignition and Combustion of Individual Aluminum Particles Below 10 μm by Microscopic High-Speed Cinematography

Hou

Wang

2020

Processes

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“…Once the metal core is melted away into the liquid (a = 1), the particle temperature rises again. The rate of change of liquid mass fraction and overall liquid mass in the droplet can be expressed as [27,28]:…”

Section: Ignition Model Of Single Micron-sized Aluminummentioning

confidence: 99%

“…The ignition of aluminum may be initiated after the cracking of oxide film, but the removal of the oxide film concurrent with the oxide melting would be more probable cause for the particle ignition [27]. At the high heating rate (10 6 -10 8 K s À1 ), the oxide film will crack due to a large thermal stress at the interface between aluminum and the oxide film in stages I and II.…”

Section: Ignition Model Of Single Micron-sized Aluminummentioning

confidence: 99%

Experiments and Numerical Calculations on Laser‐induced Ignition of Single Micron‐sized Aluminum Fuel Particle

Zhou

2017

Propellants Explo Pyrotec

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This paper presents the experiments and numerical calculations on the laser-induced ignition of single micron-sized aluminum particle in an atmospheric pressure air flow at low Reynolds number. Experimental results demonstrate that the radiation intensity of single micron-sized aluminum particle, during ignition, experiences first sharp rising, stable equilibrium and second steep rising stages. A simplified analytical model was built and numerically solved. Numerical results show that the three distinctive stages represent the heating, melting and evaporation, respectively. Laser radiation mainly contributes to heat aluminum particle, leading to phase transition (melting). The heat released from heterogeneous surface reaction (HSR) domi-nates the temperature rise of the liquid aluminum and accelerate its evaporation. During ignition, the heat loss of natural convection significantly affects the ignition performance of aluminum particle, while the heat loss of radiation toward the surrounding air only affects the evaporation rate. Threshold ignition energy of aluminum particle based on numerical calculations is in good agreement with the experiments, which strongly depends on the particle diameter. Ignition delay time depends on the particle diameter and ignition energy. This study will be beneficial to deeply recognize the ignition mechanism of single micron-sized aluminum particle, especially in the transition region between nanoscale and microscale.

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“…The three-staged ignition phenomenon was reported only for micron-sized aluminum [24,25], but it has never been experimentally demonstrated for nano aluminum at such high heating rates of the magnitude of 10 4 K/s. Ermakov et al [26] demonstrated that during ignition a horizontal melting length of micron-sized Al particle was visible.…”

Section: Ignition Stage Of Al Nanoparticlesmentioning

confidence: 99%

Effect of Heating Rate on Ignition Characteristics of Newly Prepared and Aged Aluminum Nanoparticles

Jin

Yang

et al. 2020

Propellants Explo Pyrotec

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Aluminum (Al) nanoparticles have been widely applied in propellants, but the ageing of Al nanoparticles will result in the degradation of propellant ignition performance. This paper experimentally investigates the ignition characteristics of newly prepared and aged Al nanoparticles, and improves the ignition performance of aged Al nanoparticles through elevating the heating rate. It was observed that, despite newly prepared or aged Al nanoparticles, their ignition included three stages: stage I – heating, stage II – melting, and stage III – evaporation. The temperature rise and time in stage I, melting temperature, and time in stage II and ignition temperature in stage III were separately discussed. It is found that the duration of each stage during the ignition of aged Al nanoparticles was much longer than that of newly prepared Al nanoparticles, testifying that ignition temperature of Al nanoparticles increased and ignition delay time elongated due to ageing. At elevated power density, the heating rate of Al nanoparticles increased, the heating, melting, and evaporating time shortened. The difference of ignition delay time between newly prepared and aged Al nanoparticles was significantly reduced. It means that the ignition performance can be improved through increasing the heating rate. Simultaneously, the energy conversation equation of each stage was built and discussed. It will be beneficial to deeply understand the ignition process and reveal the ignition mechanism of aged Al nanoparticles.

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Modeling of aluminum particle combustion with emphasis on the oxide effects and variable transport properties

Cited by 32 publications

References 40 publications

Laser-Induced Ignition and Combustion of Individual Aluminum Particles Below 10 μm by Microscopic High-Speed Cinematography

Laser-Induced Ignition and Combustion of Individual Aluminum Particles Below 10 μm by Microscopic High-Speed Cinematography

Experiments and Numerical Calculations on Laser‐induced Ignition of Single Micron‐sized Aluminum Fuel Particle

Effect of Heating Rate on Ignition Characteristics of Newly Prepared and Aged Aluminum Nanoparticles

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