A Thermokinetic Model for the Combustion of Strobe Composition

Matthew L. Davies

Abstract: A model chemical reaction scheme, in which a substance undergoes a two-stage decay process, is developed. It is shown that this reaction scheme follows the Shimizu hypothesis for pyrotechnic strobe combustion; both decay stages are temperature dependent with only the second generating a significant quantity of heat. The model is derived from the combustion reaction between ammonium perchlorate and fine magnesium powder although reaction of other strobe compositions is expected to proceed in a similar manner. It will be shown that the effects of additives, such as potassium dichromate as a frequency modifier, can be investigated without explicitly including them in the model. The model is therefore a first step towards a useful design tool for developing compositions with specific strobe characteristics.

Keywords:
thermokinetic model, strobe composition, Shimizu hypothesis, bifurcation theory, two-stage decay


Ref: JPyro, Issue 27, 2008, pp42-49
(J27_42)


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2 Responses to “A Thermokinetic Model for the Combustion of Strobe Composition”

  • bsturman:

    I am very interested, and puzzled, by the reference to the “Orion Flashing Guns” composition said to have been discovered by Brock’s Fireworks in 1898.

    The reference (reference 2) to Alan St Hill Brock’s “Pyrotechnics: The History and Art of Firework Making” gives the date as 1898. The author was born in 1886 – it seems most unlikely that he wrote a book at the age of 12. My copy (and all other reference to this work that I have seen) is dated 1922. There is no reference in there, as far as I can tell, to “Orion Flashing Guns”, nor is the formula given in the text to be found in this book. The other reference (which I have not seen) is dated 1994 – obviously this cannot be a primary source for a composition said to have been discovered in 1898. It would be wonderful to have a proper reference – but does one exist? If not, where did the formula come from?

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