Condensed Liquid and Solid Explosives

Detonation (and Explosion) of Condensed (Liquid and Solid) Explosives. 

Detonation and explosion in condensed phase (solid or liquid as opposed to gas, dust or vapor) explosives were briefly discussed in Vol 3 of our Encycl, p C495-R, under Condensed Explosives , but the following comments of C.G. Dunkle (Ref 22) may be added. His discussion is based mainly on the information obtained at the lOthSympCombstn (1964) and other Symposiums 

Detonation in gases has been mote thoroughly investigated than in condensed phases, and continues to receive the major share of attention. In a broad sense the chain of events is the same in both cases (Ref 7, p 2), but in gases is spread out in both space and time, being therefore more easily observed 

It should be noted that solid explosives may be detonated in any condition from a coarse powder to a single crystal (Ref 6, p 166). Heterogeneous polycrystalline mixtures can be termed solid only by convention phenomena such as grain erosion in the detonation reaction zone are of dominant importance. They depend in a complex way on the intercrystalline free space and on a free space more strictly defined, the difference between the volume of the crystals and the volume of the ions therein 

Nevertheless the conditions within the detonation front must profoundly modify the physical structure. Whether or not it can any longer be considered a solid phase, hydro-dynamic theory has been applied to the study of detonation in initially solid explosives  

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Detonation (and Explosion) in Condensed Media (or Phase). See Detonation (and Explosion) of Condensed (Liquid and Solid) Explosives and also Detonation (and Explosion) of Composite Explosives... 

Minimize accumulations of condensed liquids. Balance airflow without dampers to prevent unwanted change of airflow rates, and eliminate accumulations of condensed liquids and solids. Provide air-cleaning devices (air filters, scrubbers, etc.) with protection measures against the consequences of gas explosions (refer to the section titled Protective Measures ). 

In the deduction of the explosive combustion, study of liquid and solid explosives separately is not a must. When heat is transferred to the solids, they start to liquefy. And the liquids follow the above combustion rules. Figure 2.2 indicates that the combustion of condensed explosives is similar to that of flammable gases under steady condition. The only difference is that for gas combustion aU mixtures are gases while the gases are obtained by evaporation of liquids. 

Bowden, F. R und Yoffe, A. D. Initiation and Growth of Explosions in Liquids and Solids, Cambridge University Press. Cambridge 1952 Taylor, J. Detonation in Condensed Explosives, Clarendon Press, Oxford 1952 Cook, M. A. The Science of High Explosives, Reinhold, New York 1958 Roth, J. F Explosivstoffe 23-31 45-54 (1958)... 

The most common solvent is water. Water dissolves a great many gases, liquids, and solids, and is much used for this purpose. Other liquids similarly dissolve many substances without reacting chemically with them. Important considerations in connection wfith the choice of solvent for a given case are (1) vapor pressure and boiling point, (2) solvent power under stated conditions of temperature. (3) ease and completeness of recoverability by evaporation and condensation, and completeness of separation from dissolved material by evaporation. (4) heat of vaporization, (5) miscibility with water or other liquid, if present, (6) inertness to chemical reaction with the materials present, and with the apparatus, (7) inflammability and explosiveness. (8) odor and toxicity (9) cost of solvent, loss in process, cost of recovering. 

The term explosion is best defined as a process that involves a sudden release of energy resulting in a rapid and significant buildup of overpressure. Explosions can be categorized into physical/mechanical and chemical explosions. For example, an explosion caused by a sudden release of compressed gas is a physical explosion. A chemical explosion is caused by a chemical reaction(s), which could be combustion, exothermic decomposition or exothermic reaction. Chemical explosions can occur in gas, liquid or solid phase. Chemical explosions that occur in liquid and solid phases are sometimes called condensed phase explosions. Explosive explosions fall in this category. 

Given the thinness and complexity of the interface between the condensed phase and near surface gas region, there are no ideal methods to probe the chemistry directly. At present, one must resort to experiments that simulate some or all of the conditions of combustion or explosion. The most relevant experiments employ rapid heating, realistic pressures, and allow gases, liquids and solids to be present simultaneously. 

Spherical detonation waves can also be produced by condensed expls (solid ot liquid), especially if the charges are spherical in shape and they are initiated in the center. The above discussion of Baum et al applies to both gaseous and condensed expls. Addnl information on spherical detonation of solid explosives can be obtd from the works of Landau 8c Stanyukovich (Ref 2), Jones Miller (Ref 3), Wecken Sc Muecke (Ref 4a), Lutzky (Ref 26), Rudlin (Ref 26a) and Green James (Ref 27)... 

Some of the quantitative consequences of hot spot theory were presented in Ref 19. A qualitative discussion of heat flow in a compressed gas bubble hot spot was also presented in Ref 19. The necessity of having enough, but not too much, liquid or solid spray or foam within a compressed gas bubble (in order to have sufficient heat flow from the bubble to the surrounding condensed explosive) provides another hard-to-control variable in impact testing and thus increases the variability of test results... 

Among Ya.B. s interests were the combustion of gases and solid rocket fuels, of condensed liquid explosives and powders, the combustion of premixed fuel compounds, and diffusive combustion. In every one of his lines of inquiry he obtained fundamental results which served as starting points for numerous theoretical and experimental studies in the USSR and worldwide. 

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