Abstract
Summary In summary, the theory can be made to agree with the experimental data for unassisted deflagration of pure AP by a suitable adjustment of the available parameters. This involves, however, the introduction of an energy loss to the system which is not presently accounted for This loss may be due to three-dimensional effects, that is, to energy transfer from the c -phase or g -phase of the pellet to the ambient atmosphere. The experiments in varying pellet dimensions and ambient atmosphere, which are quoted in the Introduction, suggest that these effects are not important. However, the reported results were based on a rather small number of tests, 15 and conclusive experimental proof of the validity of a one-dimensional model is presently lacking. Representative estimates have been made for the radiant-energy emission from the g -phase above the deflagrating AP pellet 15 for the purpose of estimating the radiant-energy loss from the combustion products to the outside as well as the radiant heat transfer to the pellet surface. The model taken for this analysis is that of a radiating, homogeneous gas enclosed in a rectangular parallelepied of square base equal to the pellet edge dimension r′ and of height h (Fig. 3). Specific calculations were made for ( h/r′ )=5 and for various values of r′ . These estimates were examined by rough arguments, 17 and it was concluded that the radiant-energy terms were small, and that they could be significant in the theory only if b fell to small values around p DL . The calculated b versus p Curve No. S of Figure 4 shows that this condition is not met. A precise method of evaluating the effects of g -phase losses on deflagration limits remains to be determined. Finally, the disagreement in slope between the theoretical and experimental curves for pure AP in Figure 2 may be in part due to a presently unknown experimental scaling factor on the radiant energy absorbed by the pellet.
Published Version
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