Detonation conditions

The British Standards Institnte standard specification BS 7244 (1990) applies to both deflagradon (end-of-line and in-line) and detonadon flame arresters. For end-of-line deflagradon flame arresters ten tests are reqnired, and for in-line deflagradon flame arresters fifteen tests are reqnired. For detonation flame arresters three tests at increasing lengths of pipe for both deflagration and detonation conditions and ten nnrestricted overdriven detonation tests are reqnired. Endnrance bnrning test procedures are presented, bnt tests are condncted only if specified. 

OB can be used to predict the fumes generated by an expl. If the OB is positive, the ifumes will contain highly toxic oxides of nitrogen. For negative OB, oxides of nitrogen will be minimal but the fumes may contain a substantial amount of CO. As discussed below, relatively little CO is produced under detonation conditions by high density expls. 

Q (see Vol 7, H38-L), or the related quantity, njTj, where nj is the number of moles of gas under steady (Chapman-Jouguet) detonation conditions and Tj is the detonation temp-. 

The purpose of this test is the same as the previous one. The critical volume is the sphere diameter of a substance, below which it is impossible to obtain detonation conditions under the influence of a firing blasting charge. These tests can only be conducted on shooting ranges and sometimes with large substance quantities. 

The constants a and p were first chosen to give the best fit to experimental detonation velocity measurements for a wide variety of materials. They have more recently been revised by Cowan and Fickett to give better agreement with experimentally measured detonation pressures. For numerous other approaches to the problem of the equation of state under detonation conditions, readers are referred to the book by Cook and a paper by Jacobs. 

High-pressure experiments promise to provide insight into chemical reactivity under extreme conditions. For instance, chemical equilibrium analysis of shocked hydrocarbons predicts the formation of condensed carbon and molecular hydrogen.17 Similar mechanisms are at play when detonating energetic materials form condensed carbon.10 Diamond anvil cell experiments have been used to determine the equation of state of methanol under high pressures.18 We can then use a thermodynamic model to estimate the amount of methanol formed under detonation conditions.19... 

Quantum mechanical methods can now be applied to systems with up to 1000 atoms 87 this capacity is not only from advances in computer technology but also from improvements in algorithms. Recent developments in reactive classical force fields promise to allow the study of significantly larger systems.88 Many approximations can also be made to yield a variety of methods, each of which can address a range of questions based on the inherent accuracy of the method chosen. We now discuss a range of quantum mechanical-based methods that one can use to answer specific questions regarding shock-induced detonation conditions. 

As a general rule, fireworks do not involve detonation conditions and so their effects are restricted to blast and sound waves. Pressures in the shock front of blast waves are much lower than detonation pressures and blast pressures are normally quoted as overpressures. 

If ruby s (C02/CO) ratios come near to being correct, Arbitrary 1 (Table I) approximates the detonation condition for high-density explosives at the C-J point while, from the correspondence with usual types of calorimetric measurements,5 it is likely that Arbitrary 2 represents a condition after the gases have expanded to several (possibly 2-20) charge diameters. Arbitrary 3 might correspond to a situation much farther down the isentrope. 

Figure 13, which is a graphical representation of the ZND theory, shows the variation of the important physical parameters as a function of spatial distribution. Plane 1 is the shock front, plane 1 is the plane immediately after the shock, and plane 2 is the Chapman-Jouguet plane. In the previous section, the conditions for plane 2 were calculated and u was obtained. From u and the shock relationships or tables, it is possible to determine the conditions at plane 1. Typical results are shown in Table 5 for various hydrogen and propane detonation conditions. Note from this table that (/02/yOi) = 1.8. Therefore, for many situations the approximation that is 1.8 times the sound speed, 02, can be used. 

Up to this point, both for detonation as well as nonreactive shock waves, we have examined special ideal conditions such as uniaxial phenomena (one dimensional without edge effects) and only at ideal detonation conditions in explosives at unspecified lengths. In this session we will explore the phenomena that exist outside these limits. These phenomena, the effects of physical dimensions and temperature, are very complex, and so we will treat them only on the empirical level. We will also look somewhat into methods of estimating or scaling these effects where possible. 

Safety trials were conducted to investigate the behaviour of the core of a nuclear device under simulated faulty detonation conditions. The core is destroyed by the conventional explosive detonation of such a device, with the production of finely divided plutonium and plutonium oxide which are widely dispersed if the test is not confined. Usually no fission takes place, though there was a very small fission energy release in three of the French underground safety trials. (Since there was some explosive yield, these three trials are sometimes counted as nuclear tests which would put the total number of underground nuclear tests at Mururoa and Fangataufa atolls at 140 rather than 137.) All of the 15 safety trials were carried out at Mururoa. 

DRE not published, but should approach 100 percent under confined detonation conditions. 

Furthermore, most practical energetic materials are molecular solids that have relatively short atomic correlation lengths under detonation conditions. This enables the use of small simulation cells and satisfaction of the strain rate condition Eq. (21) shortly behind the shock front. 

Propagation is thought to occur by decomposition in the solid phase with with the reaction proceeding from layer to layer. The plateau velocity ( 2.9 km/sec) is the velocity of sound in the crystal. This will be the maximum velocity for heat conduction until the pressures in the reaction front are sufficient to build up a shock wave and, eventually, full detonation conditions (for crystals >2 mm diameter). Chaudhri and Field explain the initial velocity/crystal thickness results in terms of heat losses from the reaction front. 

When the rocks and soils are just thrown up, the sparse waves transport into them because of the relatively lower surrounding pressure. At the same time, the sparse waves crush the rocks and soils further. According to the throwing index n, there are several explosion/detonation conditions, which are listed below. 

Loading medium Loading diameter (mm) Detonation condition Detonation velocity (m/s)... 

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