Density effect on detonation reaction zone length in solid explosives

For condensed explosives, containing metal particle additives, interaction of the detonation shock and reaction zone with solid inclusions leads to high rates of momentum and heat transfer that consequently introduce non-ideal detonation phenomena. During the time scale of the leading detonation shock crossing a particle, the acceleration and heating of metal particles are shown to depend on the volume fraction of particles, dense packing configuration, material density ratio of explosive to solid particles and ratio of particle diameter to detonation reaction-zone length. Dimensional analysis and physical parameter evaluation are used to formalize the factors affecting particle acceleration and heating. Three-dimensional mesoscale calculations are conducted for matrices of spherical metal particles immersed in a liquid explosive for various particle diameter and solid loading conditions, to determine the velocity and temperature transmission factors resulting from shock compression. Results are incorporated as interphase exchange source terms for macroscopic continuum models that can be applied to practical detonation problems involving multi-phase explosives or shock propagation in dense particle-fluid systems.

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Measurement of the Chapman‐Jouguet Pressure and Reaction Zone Length in a Detonating High Explosive

The Journal of Chemical Physics ◽

10.1063/1.1742255 ◽

1955 ◽

Vol 23 (7) ◽

pp. 1268-1273 ◽

Cited By ~ 70

Author(s):

Russell E. Duff ◽

Edwin Houston

Keyword(s):

Reaction Zone ◽

High Explosive ◽

Zone Length

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Dependence of Critical Diameter of Emulsion Explosive on Density in Steel Confinement

Siberian Journal of Physics ◽

10.54362/1818-7919-2013-8-3-128-134 ◽

2013 ◽

Vol 8 (3) ◽

pp. 128-134

Author(s):

Sergey Rafeichik

Keyword(s):

Reaction Zone ◽

Acoustic Impedance ◽

Detonation Front ◽

Initial Density ◽

Critical Diameter ◽

Emulsion Explosive ◽

Emulsion Explosives ◽

Minimum Diameter ◽

Zone Length ◽

Strong Confinement

Emulsion explosives (EMX) based on fine emulsion matrix are characterized by high detonation ability. Critical diameter (as minimum diameter when detonation occurs) and reaction zone length are known in the case of thin confinement with low acoustic impedance. The dependence of critical diameter of EMX in steel confinement with high acoustic impedance was examined in the range of initial density 0,75–1,37 g/cm3 . Density was varied by the concentration of glass microballoons, which were used as the sensitizer. It was shown experimentally, that characteristic value is /2 1 cr R d a  in the case of strong confinement. This can be due to the decrease of detonation front curvature. Comparison was made between the values of critical diameter in weak and strong confinement. The main distinction is that such dependence in strong confinement is lower and almost monotonic. This can indicate the influence of some processes besides lateral rarefaction wave. Period of reaction is closely connected with critical diameter and reaction zone length. Model based on heterogeneous kinetic of heating of emulsion surrounding single microballoon was proposed to describe the experimental dependence of the reaction zone time of EMX on concentration of microballons

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Observations of detonation in solid explosives by microwave interferometry

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1958.0258 ◽

1958 ◽

Vol 248 (1255) ◽

pp. 499-521 ◽

Cited By ~ 17

Keyword(s):

Activation Energy ◽

Detonation Velocity ◽

Fringe Pattern ◽

Detonation Front ◽

Beam Theory ◽

Kcal Mole ◽

Zone Length ◽

Solid Explosive ◽

Interferometric Technique ◽

Solid Explosives

Detonation processes have been observed in narrow, heavily confined, columns of solid explosive by a new microwave interferometric technique. The technique is described and a multiple-beam theory of fringe shape is given. The location, with respect to the detonation front, of the surface reflecting the microwaves is discussed. Detonation velocity as a function of distance along the column is derived from an oscilloscope display of the fringe pattern. The calculation of the detonation velocity requires a knowledge of the wavelength of the microwaves in the explosive. For this purpose the relative permittivities of a number of explosives are given as a function of their pressed density. The accuracy and applications of the method are discussed. Experiments on tetryl are described in which the technique is evaluated by observing the detonation velocity for a range of densities, and is applied to resolution of the velocity transient during growth to detonation. A simple theory of growth is used to estimate the reaction zone length (0.4 mm) and the activation energy (2 kcal/mole) in the detonation of tetryl.

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