Determining the relationship between critical conditions of detonation propagation and the average decomposition rates of explosives in detonation waves

2019 ◽  
Author(s):  
S.G. Andreev
Keyword(s):  
Detonation Velocity ◽  
Detonation Front ◽  
Critical Diameter ◽  
Critical Conditions ◽  
Detonation Waves ◽  
Reacting Flow ◽  
Kinetics Equation ◽  
Charge Diameter ◽  
Formal Kinetics ◽  
Dimensional Approximation

The study introduces a model of steady propagation of non-ideal detonation of open cylindrical charges with diameters close to critical ones. The model was obtained in the quasi-one-dimensional approximation with the use of analytical methods. We found a solution for the model’s closing equation, which directly relates the average decomposition rate in the detonation front, determined by the parameters of the formal kinetics equation and dependent on the detonation rate, the gas-dynamic parameters of the initial explosive and its reaction products (isentropic exponents), the duration of the chemical peak and ideal detonation velocity, and also the ratio of the charge diameter to the duration of the chemical peak of the ideal detonation. We obtained an equation which reflects the dependence of the non-ideal detonation velocity on the charge diameter. The critical diameter is determined as the range boundary of the charge diameter values at which this equation still has a solution. The study shows that the expression for the fundamental characteristics of the detonation process, i.e. the ratio of the spread time and the reaction time of the explosive, differs from the expression used in the Khariton principle when taking into account the divergence of the reacting flow in the curved detonation front. As for the critical value of this ratio, in general it is different from the unity and is a variable value depending on the characteristics of the kinetics of decomposition of a substance in shock waves. Based on the calculations, we draw a conclusion that changes in the microstructure of the explosive charge of the same composition, displayed by changes in the parameters of the formal kinetics equation, are accompanied by relative changes in the critical diameter, many times greater than the relative changes in the duration of the chemical peak of ideal detonation

scholarly journals A Novel Melt Cast Composite Booster Formulation Based on DNTF/TNT/GAP-ETPE/Nano-HMX

2016 ◽  
Vol 2016 ◽  
pp. 1-5 ◽  
Author(s):  
Shuo Yu ◽  
Hequn Li
Keyword(s):  
Detonation Velocity ◽  
Thermoplastic Elastomer ◽  
High Energy ◽  
Safety Performance ◽  
Detonation Waves ◽  
Small Scale ◽  
Mass Ratio ◽  
Critical Detonation Diameter ◽  
Gap Test ◽  
The Impact

To obtain the melt cast booster explosive formulation with high energy and low critical detonation diameter, melt cast explosives were designed by 3,4-bis(3-nitrofurazan-4-yl)furoxan (DNTF)/2,4,6-trinitrotoluene (TNT)/glycidyl azide polymer-energetic thermoplastic elastomer (GAP-ETPE)/nano-1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX)/Aristowax. Furthermore, the impact sensitivity, small scale gap test, rheological properties, propagation reliability, and detonation velocity were measured and analyzed. The results show that when the mass ratio of DNTF/TNT/GAP-ETPE/nano-HMX/Aristowax is 34.2/22.8/2/40/1, not only does it indicate excellent rheological property but it has a brilliant safety performance as well. Moreover, it can propagate the detonation waves successfully in the groove at 0.7 mm × 0.7 mm. When the charge density in the groove is 1.70 g·cm−3, its detonation velocity can reach 7890 m·s−1.

Shock Fitting and Numerical Modeling of Detonation Waves

1997 ◽  
Vol 08 (06) ◽  
pp. 1193-1207
Author(s):  
Muhammad Akram ◽  
Farhad Ali
Keyword(s):  
Numerical Modeling ◽  
Numerical Modelling ◽  
Simple Form ◽  
Detonation Front ◽  
Detonation Waves ◽  
Jump Conditions ◽  
Method Of Integral Relations ◽  
Complete Set ◽  
Integral Relations ◽  
Shock Fitting

Numerical modelling of detonation using shock fitting is described in detail. A complete set of jump conditions that hold across the detonation front is presented in a simple form. Validity and accuracy of the model has been established by comparison with published results and results of another model utilizing the method of integral relations. A brief description of the later model is given to highlight its validity and limitations.

scholarly journals The EFP Formation and Penetration Capability of Double-Layer Shaped Charge with Wave Shaper

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4519
Author(s):  
Yakun Liu ◽  
Jianping Yin ◽  
Zhijun Wang ◽  
Xuepeng Zhang ◽  
Guangjian Bi
Keyword(s):  
Detonation Wave ◽  
Double Layer ◽  
Detonation Velocity ◽  
Incidence Angle ◽  
Shaped Charge ◽  
Experimental Simulation ◽  
Detonation Waves ◽  
Forming Process ◽  
Large Length ◽  
Overdriven Detonation

Detonation waves will bypass a wave shaper and propagate in the form of a horn wave in shaped charge. Horn waves can reduce the incidence angle of a detonation wave on a liner surface and collide with each other at the charge axis to form overdriven detonation. Detection electronic components of small-caliber terminal sensitive projectile that are limited by space are often placed inside a wave shaper, which will cause the wave shaper to no longer be uniform and dense, and weaken the ability to adjust detonation waves. In this article, we design a double-layer shaped charge (DLSC) with a high-detonation-velocity explosive in the outer layer and low-detonation-velocity explosive in the inner layer. Numerical and experimental simulation are combined to compare and analyze the forming process and penetration performance of explosively formed projectile (EFP) in DLSC and ordinary shaped charge (OSC). The results show that, compared with OSC, DLSC can also adjust and optimize the shape of the detonation wave when the wave shaper performance is poor. DLSC can obtain long rod EFPs with a large length-diameter ratio, which greatly improves the penetration performance of EFP.

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

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

Observations of detonation in solid explosives by microwave interferometry

1958 ◽  
Vol 248 (1255) ◽  
pp. 499-521 ◽  
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.

MECHANISM OF DETONATION IN EXPLOSIVES

Geophysics ◽  
1944 ◽  
Vol 9 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Robert W. Lawrence
Keyword(s):  
Shock Waves ◽  
Detonation Wave ◽  
Wave Front ◽  
Detonation Velocity ◽  
High Velocity ◽  
Hydrodynamic Theory ◽  
Detonation Waves ◽  
Energy Propagation ◽  
Low Velocity ◽  
Detonation Wave Front

Results of photographic work on the detonation of high explosives are presented and discussed in their relationship to the hydrodynamic theory of detonation. The two most important properties of an explosive are its strength and its detonation velocity. Methods for determining these quantities are described. A moving film camera of the rotating drum type is especially useful in determining detonation velocity and in studying the nature of detonation. The photographic results, which are illustrated by a number of pictures, are helpful in demonstrating various elements of the theory. These photographs illustrate the nature of detonation waves in explosives and of shock waves in air. The duration of the detonation waves in nitroglycerin and blasting gelatin is less than one millionth of a second and the duration of the shock waves produced by these explosives in air is of the same order. The high temperature of shock waves which is predicted by theory is confirmed by the intense luminosity shown in photographs. The relatively low temperature predicted for shock waves in liquids is similarly confirmed by the absence of luminous shock waves in water. Photographs are included showing the propagation of detonation from one cartridge of blasting gelatin to another across air gaps and water gaps. In the latter case no visible shock wave is produced in the water and the highly luminous after‐burning is eliminated. Calculated values of the detonation velocity for nitroglycerin, blasting gelatin and 60% gelatin dynamite are in approximate agreement with the experimentally determined values. Calculations indicate that pressures in the detonation wave may run as high as 140,000 atmospheres and temperatures to 4300°C. The shape of the detonation wave front in a high velocity explosive like blasting gelatin is apparently planar whereas in low velocity explosives it is convex. The actual mechanism of energy propagation in detonation is not clearly understood out probably involves activation of the explosive at the detonation wave front by high velocity products of the detonation which are projected forward at speeds even greater than the detonation velocity.

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