Velocity — Charge Diameter and Density Relationships

DETONATION VELOCITY-CHARGE DIAMETER AND DENSITY RELATIONSHIPS 

Accdg to Price (Ref 15), in studying shock-to-detonation transitions a frequent question is whether a certain expl is extremely insensitive to shock or is, in fact, nondetonable under the test conditions. To answer it, some investigation must be made of the critical diam (dc) of cylindrical chges, i.e., that diam above which, deton propagates and below which deton fails. The loading density rather than the diam can be varied in that case, the critical density (pc) is detd. Pairs of such values form the detonability limit curve which divides the d—vs—p plane into one region where deton can occur and another where it must fail. 

Failure of deton just below the critical diam is attributed specifically to rarefactions entering the reaction zone and quenching the reaction. Therefore, there is a close dependence 

Prior to publication of papers by Price (Ref 15) and by Gordon (Refs 13 14), considerable work on relationship between density, diameter and detonation velocity was done in the US by Cook s group as described in his book (Ref 6) and also in Russia by many investigators (Refs 1, 2, 3, 4, 7, 8 9). Some work was done in Germany by Bichel Kast and in France by Dautriche others. Some work done in France after WWII is described in Ref 5. More recent Rus work is described in Refs 10, 11 12 

Cook et al (Ref 6, pp 44-57) found that velocities in the ideal detonation of gases are much.less sensitive to the initial density (designated by him as pp than in condensed explosives. Curves given in Fig 2.2 and Fig 3-3, p 47 (our figs 1 8t 2) show relationships D vs p for HBX Tritonal are nonlinear and D vs d(diameter) have some anomalous depressions. This was observed in 1954, but was withheld from publication until 1957, when Berger et al (Ref 5) observed in France the same phenomenon in their. D vs p curves for mixtures of PETN and Al, p = 0.92  

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Fig 3-2, p 47 gives velocity versus density of the above expls, while Fig 3.3 deals with velocity vs diameter for the same expls. Both of these Figs are reproduced here as Figs 1 2 under DETONATION VELOCITY-CHARGE DIAMETER AND DENSITY RELATIONSHIPS. These curves were obtd at large enough.diameters to ensure ideal deton... 

For determination of critical diameters, the test s described under Detonation Velocity-Charge Diameter and Density Relationships, Experimental Procedures can be used... 

Detonation Velocity, Influence of Charge Diameter on. See Detonation Velocity, Charge Diameter and Density Relationships... 

Limiting (or Critical) Charge Density-Diameter of Explosive Charges. See Detonation Velocity-Charge Diameter and Density Relationship in Encycl 4 (1969), D641-L to D656-L... 

Detonation Velocity - Charge Diameter and Density Relationship (pp D646-L to D654-R) Detonation Velocity and Chemical Composition and Detonation Velocity as a Function of Oxygen Balance and Heat of Formation (pp D656-L to D657-L)... 

Detonation velocity-charge diameter and density relationships 4 D646... 

Detonation-Critical and Limiting Charge Densities, Charge Diameters and Detonation Velocity Relationships. See under DETONATION VELOCITY-CHARGE DIAMETER-DENSITY RELATIONSHIPS... 

Most of this section on relationships between charge densities, charge diameters and detonation velocities was compiled using the reports and papers listed in CA up to 1961. 

Density - Detonation Velocity - Diameter of Charge Relationships. See under Detonation Velocity - Charge Density Relationship and Detonation Velocity - Charge Diameter Relationship... 

See under Detonation Velocity-Charge Density Relationship and Detonation Velocity-Charge Diameter Relationship... 

X-ray absorption furnishes an absolute measure of the density of matter. However, in many applications the important observations to be made with X-rays concern the geometrical relationships of shock fronts and contact surfaces it is in this area where X-rays, because they make it possible to sefe inside the detonating expl, provide a uniquely appropriate tool. Until recently the difficulty has been the inability of available sources to penetrate charges more than a few inches in diameter. With the advent of the PHERMEX machine this difficulty has been overcome. Phermex provides a pulsed beam of 27 Me V electrons in 0.1 microsec bursts, which impinge on a tungsten target to generate X-rays that can easily penetrate several cm of HE. Recall that density of the shocked material can be related to particle velocity thru the conservation equations (see Vol 7, HI 79)... 

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