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Reactive Flow and the Size Effect
Author(s) -
Clark Souers P.,
Anderson Steve,
McGuire Estella,
Murphy Michael J.,
Vitello Peter
Publication year - 2001
Publication title -
propellants, explosives, pyrotechnics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.56
H-Index - 65
eISSN - 1521-4087
pISSN - 0721-3115
DOI - 10.1002/1521-4087(200101)26:1<26::aid-prep26>3.0.co;2-3
Subject(s) - explosive material , detonation , exponent , radius , constant (computer programming) , mechanics , thermodynamics , detonation velocity , chemistry , reaction rate constant , materials science , physics , kinetics , classical mechanics , philosophy , linguistics , computer security , organic chemistry , computer science , programming language
The detonation reaction rate in μs −1 is derived from Size Effect data using the relation – DU s (∂ U s /∂y) −1 , where y =1/ R o , where U s is the detonation velocity for a ratestick of radius R o and D is the infinite‐radius detonation velocity. These rates are generally not constant with radius and have pressure exponents ranging from <−5 to > 5. JWL++, a simple Reactive Flow code, is run with one rate constant on many samples to compare its rates. JWL++'s pressure exponents vary from about 0.5 to 2.5, and failure occurs outside this range. There are three classes of explosives: (1) those for which the pressure exponent is between 1 and 2 and the rate is nearly constant (e.g. porous urea nitrate); (2) higher pressure explosives with a concave‐down shape and large positive pressure exponents (dense TNT); and (3) explosives with negative pressure exponents and concave‐up shapes (porous PETN). JWL++ fits only the first class well and has the most trouble with class 3. The pressure exponent in JWL++ is shown to be set by the shape of the Size Effect curve – a condition that arises in order to keep a constant reaction rate for all radii. Some explosives have too much bend to be modeled with one rate constant, e.g. Comp. B near failure. A study with creamed TNT shows that the rate constant need not be changed to account for containment. These results may well be pertinent to a larger consideration of the behavior of Reactive Flow models.