THEORETICAL STUDIES ON THE SUSCEPTIBILITY OF BOMBS TO THERMAL INITIATION WHEN SUBJECT TO A LIQUID HYDROCARBON FIRE.
Rept. no. 1 on Studies in the prediction of the response of ordnance items engulfed in hydrocarbon fires,
NAVAL ORDNANCE LAB WHITE OAK MD
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Times to explosion of Mk-81 bombs engulfed in hydrocarbon fires were calculated for various fire temperatures and thicknesses of hot melt internal liner. Since the experimental explosion times in bomb cook-off tests were much less than the calculated times to explosion, it has been concluded that the hot melt loses its insulating properties at temperatures above its softening point. In a given bomb the hot melt thickness often is not uniform. Moreover, the heat flux in a given fire usually varies with location. Calculations indicated that the worst conditions i.e. thinnest hot melt thickness, largest heat flux, rather than the average conditions, should be used in predicting the response of ordanance items flame envelopment. It was found that the effect of the explosive kinetic parameters i.e. activation energy and frequency factor on the times to explosion of Mk-81 bombs was significant. Using literature values of the kinetic parameters, calculated times to explosion of H-6 in a steel pipe were found to agree well with experimental explosion times. Author
- Aerial Bombs