Sizing and burn time measurements of micron-sized metal powders

Document Type

Article

Publication Date

7-17-2009

Abstract

Detailed ignition and combustion mechanisms are needed to develop optimized propellant and energetic formulations using micron-sized metal powders, such as aluminum. Combustion researchers have traditionally used relatively coarse metal particles to characterize the burn time dependence on particle size. However, measurements of burn times for particles below 10 μm in diameter are still needed for aluminum powders and other metal fuels. The apparatus described here sizes the particles just before the ignition event, providing a direct correlation between individual particle size and its burn time. Two lasers were utilized: a 785 nm laser diode for sizing the particles and a 125 W CO2 laser for particle ignition. The particles crossed the 785 nm laser beam just before crossing the CO2 laser beam. The particle size was determined from the amplitude of the scattered 785 nm light pulse. The burn time was determined from the duration of the visible light emission produced from the ignited particle. The in situ measured particle size distributions compared well with the size distributions measured for the same powders by a commercial instrument using low angle laser light scattering. Our measurements with two nominally spherical aluminum powders, suggest that the burn times increase from 0.5 to ∼2.5 ms as the particle diameters increase from 3 to 8 μm. © 2009 American Institute of Physics.

Identifier

67650333637 (Scopus)

Publication Title

Review of Scientific Instruments

External Full Text Location

https://doi.org/10.1063/1.3133712

ISSN

00346748

Issue

6

Volume

80

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