Diameter effect

A. W. Campbell and R. P. Engelke, "The Diameter Effect in High Density Explosives," in 6th Symposium (International) on Detonation ACE-221, ONR, Dept, of Navy, Arlington, Va., 1977. 

There are few quant data for D vs d for PETN. However, it is certain that the diameter effect for PETN is quite small. This becomes apparent when one considers that the critical diameter for PETN (at p = 1 g/cc and 0.025-0.1 mm particle size) is only 0.9mm (Bobelev quoted in Ref 22, p 348), and becomes smaller at p> 1. Cook et al (Ref 18) show that D varies from about 4800m/sec at d=0.32cm to 5400 m/sec at d> 1.6cm, for —65 to +100 mesh PETN at 0.95g/cc. Since confinement effects parallel diameter effects, D for PETN is almost independent of confinement for any practical size charges. 

At short distances, approximately equal to the excluded volume diameter, effective pair forces obtained from force matching exhibit unphysically large fluctuations. This is largely due to inadequate sampling of configurations at short distances in... 

Effect of diameter, size, and orientation of heater Using data available then, Bernath (1960) studied the diameter effect of a horizontal cylindrical heater on the critical heat flux in pools of saturated water at atmospheric pressure. The results indicated that CHF increases as the heater diameter increases up to about 0.1 in. (2.5 mm), then levels off. 

Figure 5.68 Correlating function of hydraulic diameter effect on CHF, F(De), where F(De) = [0.2664 + 0.8357 exp( — 3.15lZ) )]. (FromTong, 1968a. Copyright 1968 by American Nuclear Society, La-Grange Park, IL. Reprinted with permission.)...

In Section V a more general relation for D is derived which introduces the diameter effect... 

The above considerations, although obtd from the one-dimensional case, may be correlated with the charge-diameter effect and limits of detonability in the three-dimensional explosions... 

Data from a single laboratory for tubes of different diameters are needed. Tubes are thicker than the bubbles produced, but the reverse is true for wires. The diameter effects may not be the same in the two cases. The equations of Rohsenow and of Forster and Zuber predict that the geometric arrangement is of no consequence. The prediction is not proved at present. 

A compilation of recent detonation velocity data taking into account D — p0 and D—Diameter effects is shown in Table 2, taken from Ref 25... 

Bolkhovitinov Viktorov (Ref 16) present diameter effect data for a number of expls including Soviet commercial expls, as shown in Table 3. (Note Trotyl is TNT.) Dj is D at infinite diameter d. The calculated (method of calcn not given) reaction zone width is a and the observed reaction zone width is a0 5 is mean square (sic) deviation presumably of a. 

Lederman et al (Ref 20) studied the detonation behavior of AMATEX-30, nominally 40/30/30 TNT/RDX/AN, at an average density of 1.645g/cc. Their results of the diameter effect (in terms of R, the charge radius) are summarized in Fig 2. Detonation failed to propagate in column diameters of 10mm. As shown, the infinite diameter D is 7.318km/sec, as compared to 7.031km/sec for Amatex 20 (40/20/40 TNT/RDX/AN). They also examined the effect of AN particle size on D. Their results for Amatex 20 are shown in Table 4... 

Engelke (Ref 24) states that there is a qualitative difference in the diameter effect curves of homogeneous and heterogeneous expls. From his observations on the behavior of neat NM (homogeneous) and admixtures of NM and silica (heterogeneous) he ascribes this difference to absence of hot spots in the former and their presence in the latter. The different behavior of homogeneous and heterogeneous expls (curved vs linear) is shown in Fig 3. It should be noted that—... 

Additional data on density and diameter effects is provided by Kegler (Ref 4) for RDX/TNT and HMX/TNT mixts. Fig 5 shows the variation of D (VQ in Kegler s notation) with initial density p with charge diameter 0 as a parameter. Fig 6 shows the variation of D with 1/0 (Eyring plot) with initial density as a parameter. Also shown are reaction zone widths as computed by the Eyring method... 

Fig 4 NM and 92.75/6./1.25 wt% NM/silica/ guar diameter-effect curves. The squares and circles superimposed on the curves are the data from Tables II and III. On the latter curve the point marked with an asterisk at 1/R=0.21mm 1 was failing. The NM and gelled material have failure points at 1/R equal to 0.123 0.003 and 0.209 0.012mm 1, respectively. Here the error bars are obtained from one-half the difference of the internal diameters of the largest stick which failed and the smallest stick which propagated... 

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,... 

Cartridge diameter effect on strength and sensitiveness of expls 2 C80... 

Campbell R. Engelke, Diameter Effect in High-Density Heterogeneous Explosives", LA-UR-76-1115, Los Alamos Sci Lab, Los Alamos (1976) CA86, 157801 (1976) 46) R,K. 

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