Detonations failure diameters

Detonation, Failure Diameter in. Same as Critical Diameter in Detonation... 

XTX-8003 (eXTrudable explosive). Los Alamos National Scientific Laboratory (LASL) designation for an extrudable expl contg PETN (80 wt% 69.9 vol %) coated with a low-temp vulcanizing silicone resin, Sylgard 182 (20 wt % 30.1 vol %) atomic compn Ci. 8<>H3.64N , 0103 3 jSi0.27 white putty curable to rubbery solid d, TMD 1.556g/cc, nominal 1.50-1.53g/cc mp 129-135°. XTX-8003 is used in special applications that require expls with small detonation failure diameters... 

SSg/cc mp 200° decompn hardness S5S. XTX-8004 is used in special applications that require more thermal stability than XTX-8003 (see above) can give. The detonation failure diameter is slightly greater than that of XTX-8003 Manufacture. Same as XTX-8003 Chemical Properties (Ref 2) ... 

H. N. Presles and C. Brochet, Induction Delay and Detonation Failure Diameter of Nitromethane Mixtures, in Gasdynamics of Detonations and Explosions, vol. 75 of Progress in Astronautics and Aeronautics, J. R. Bowen, N. Manson, A. K. Oppenheim, and R. I. Soloukhin, eds.. New York American Institute of Aeronautics and Astronautics, 1981, 282-295. 

Knystautas, R., J. H. Lee, and C. M. Guirao. 1982. The critical tube diameter for detonation failure in hydrocarbon-air mixtures. Combustion and Flame. 48 63-83. 

As described in chapter 6, detonations have a rapidly moving flame and/or pressure front. Detonation failures usually occur in pipelines or vessels with large length-to-diameter ratios. 

Zel dovich, ZhPriklMekhan i TekhnFiz 1963 (6), pp 59-65 CA 60, 14325 (1964) (Onedimensional instability and attenuation of detonation) 10a) Mary L. Pandow et al, "Studies of the Diameter-Dependence of Detonation Velocity in Solid Composite Propellants. II. Prediction of Failure Diameters , 4thONRSympDeton(1965), 102-06 11) C.G. 

Accdg to Ref 66, p 166, Manson Guenochg proposed (Ref 46b) that the decrease of deton vel with diam exhibited by gases is due to the inhibition of the chem reaction in the neighborhood of the wall over a layer of thickness 8. Then they made four assumptions (expressed by equations 5.6.1 to 5 6.4 incl of Ref 66) and came to the conclusion that the wave vel at a given diam is determined by the ideal C-J velocity and the failure diameter... 

The problem that remains is the study of the interaction of a shock with a matrix of holes in three-dimensional geometry. The basic two-dimensional processes involved in the failure of detonation, the failure diameter of explosives, and the sputtering initiation observed for density discontinuities near the critical size have been described. The three-dimensional study of the interaction of numerous failures and reignited detonations which is necessary for a complete numerical description of these problems must await new computing hardware ... 

Failure Diameter. The minimum diameter below which propagation of detonation does not take place. Also known as critical diameter... 

Akhimova Stresik (Ref 17) studied the detonation characteristics of Ammonium Perchlorate (AP) mixed with various fuels . They were primarily interested in the failure diameter (critical diameter) of these mixts, but they do report some detonation velocity measurements at the critical diameter of the mixts... 

If the brass plate were completely incompressible, the failure thickness so determined would be half that of an unconfined infinite sheet. The failure thickness of an unconfined sheet is less than the failure diameter of a cylinder because rarefactions in a cylinder enter from all sides of the charge and influence the detonation. Thus, the failure diameter may be several times the failure thickness and may vary from one expl to another. More complete details are given in Ref 3... 

The reader is referred to Ref 1 for a voluminous compilation of detonation properties (detonation velocity and diameter effect, cylinder test performance, plate dent test and detonation failure thickness), shock initiation properties (wedge test data and small and large - scale gap tests), and sensitivity tests (skid test, large-scale drop test or spigot test and spark sensitivity) relevant to LASL research expls Refs 1) T.R. Gibbs A. Popolato, LASL Explosive Property Data , Univ of California Press, Berkeley (1980) 2) B.M. Dobratz,... 

Failure in detonation of coal mining expls 4 D347 Failure diameter 6 FS... 

We are interested in reaction-zone length because it appears to be the major parameter controlling detonation velocity in the nonideal detonation region. It appears that explosives with thick reaction zones have a larger effect on detonation-velocity/diameter and failure diameters than explosives with thin reaction zones. 

The same mechanism, side losses that cause steady-state detonation velocity to decrease in the nonideal region, eventually become so dominant with decreasing diameter that a point is reached where steady-state detonation cannot be maintained. At this point detonation fails it either suddenly slows down to below the sound speed in the unreacted explosive or stops altogether. This point is called the failure diameter, D, it is also called the critical diameter, Dent- Failure diameter is strongly affected by confinement, particle size, initial density, and ambient temperature of the unreacted explosive. Failure diameter can be roughly correlated to the velocity-diameter constant a, as seen in Figure 21.7. 

Figure 21.11 Failure diameter for detonation of AP as a function of initial density. Average grain size, 10 m (Ref. 7).

The failure diameter is deduced from Fig. 8, and is approximately equal to 100 A. All the results presented so far the existence of a failure diameter, the curvature of the front and the variation of the detonation velocity with the cylinder radius, are consistent with continuum theory. Nevertheless, the necessary condition to get a steady detonation wave is the existence of a sonic point that isolates the reaction zone from the rarefaction waves coming from the back. This is investigated in the case of a planar detonation wave (using periodic boundary conditions in 3D). 

In detonation wave applications, the model has successfully calculated embedded gauge, laser interferometric metal acceleration, failure diameter, corner turning, converging, diverging, and overdriven experiments [57,61-63,67]. Figure 9 shows the measured and... 

A detonation refers to a shock wave in an energetic material that runs at a steady velocity driven by chemical reactions initiated at the shock front [38,39]. Due to damping at edges and surfaces, the detonation state can occur only if the sample is larger than the critical failure diameter [3]. With a few exceptions, the critical diameter is typically in the nun to cm range, so detonations are associated with macroscopic loads of energetic materials and are extremely powerful. For HMX, the detonation velocity is 9.1 km/s, the pressure is 39 GPa,... 

For viewing the initiation path of high explosive, combustion-to-detonation transition, determination of the failure diameter of the explosive charge, transmission of the detonation process, and for studying the establishment of stable detonation, a special types of probes combined with a fast oscilloscope are used. 

Considering that real detonations are not steady-state and that chemical equilibrium is not necessarily achieved, it is difficult to evaluate any equation of state. One can probably consider an equation of state adequate for engineering purposes if, over a wide range of density and composition, the computed and experimental pressures and temperatures agree to within 20% and the detonation velocities to within 10%. Such explosive systems usually exhibit small changes in detonation parameters with diameter, have small failure diameters, and behave like most high-energy explosive systems. It is also important that the expansion isentrope be accurately reproduced to within 5%. 

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