Applications of Detonation Phenomena

Though the density of aluminized PBX is high, the measured detonation velocity is low when compared with nonaluminized PBX. Since HMX and RDX are stoichio-metrically balanced materials, no extra oxygen is available to oxidize the aluminum particles. The aluminum particles are oxidized by CO molecules in the combustion products of HMX or RDX. Furthermore, the oxidation of the aluminum particles takes a much longer time than that of the crystalline HMX or RDX particles. The aluminum particles do not react in the detonation wave but react downstream of the CJ point shown in Fig. 3-5. Thus, no increase in the detonation velocity occurs even if the density of the PBX is increased by the addition of aluminum particles. However, when an aluminized PBX is used in water, the high temperature aluminum particles react with water to produce hydrogen gas and thus produce bubbles in the water. The bubbles generate additional pressure and a shock wave in the water. 

As described in Chapter 3, the detonation characteristics are followed by the Ran-kine-Hugoniot relationship and the detonation velocity is obtained at the Chapman -Jouguet point. Though the detonation characteristics of explosives are fundamentally the same as those of premixed gases, the physicochemical processes of explosives are more complex because the shock wave propagation in the explosives is largely different from that of premixed gases. 

Since detonative explosives are kept in various types of vessels used for different objectives such as warheads, bombs, and industrial mines and civil engineering, the performance of the explosives is dependent not only on the chemicals and mass of explosives but also the physical shape of explosives. When a detonation is initiated at a point in an explosive charge, the detonation wave propagates spherically in all directions. When a detonation is initiated at a point at one end of an explosive charge, the detonation wave propagates semi-spherically in the charge. Thus, the 

1 Engineering Design Handbook, Principles of 3 Meyer, R., Explosives, Verlag Chemie, Wein-Explosive Behavior, AMPC 706-180, US Army heim (1977). 

Material Command, Washington, DC (1972). 4 Explosives Journal, No. 27, NOF Corporation, 

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This section covers two main subjects, namely theoretical estimates of uCJ, and application of measured particle velocity histories to elucidation of initiation phenomena in detonations and to flow characteristics behind the detonation front... 

To treat the subject of thermodynamics adequately would require a whole book, nay indeed a whole encyclopedia. In this article we will present a cursory overview of thermodynamic concepts and refer the reader to standard texts on the subject. Much of the article will be concerned with applications of thermodynamics to expln phenomena and its use, in conjunction with hydrodynamics, in explaining shock and detonation processes... 

Thermodynamics and statistical mechanics deal with systems in equilibrium and are therefore applicable to phenomena involving flow and irreversible chemical reactions only when departures from complete equilibrium are small Fortunately this is often true in combustion problems, but occasionally thermodynamical concepts yield useful results even when their validity is questionable [for example, in the analysis of detonation structure (see Section 6.1.5) and in transition-state theory (see Section B.3.4)]. The presentation is restricted to chemical systems appropriate independent thermodynamic coordinates are pressure, p, volume, V, and the total number of moles of a chemical species in a given phase, N-, Moreover, results related to combustion theory are emphasized. 

Molecular collision theory. The molecular collision theory proposes that undecomposed hydrocarbon fuel molecules directly in front of the explosion wave will be bombarded and thus activated by the highly active molecules from the explosion wave itself. Garner and Saunders 85 studied this phenomena by means of the spectra of acetylene air detonations. They explain the formation of carbon in such detonations by the decomposition of acetylene into 2C and Ha by the action of molecular collisions. The application of this theory to the mechanism of the action of antiknocks in internal combustion engine operation is not clear. 

To study the detonation of liquid explosives and its spreading/transportation, nitromethane, nitroglycerine, diethyleneglycol dinitrate, and methyl nitrite are designed as the objectives of liquid explosives to study the chemical dynamics and the complex unsteady process of shock waves combustion. These phenomena determine the structure of detonation wave fronts and spreading limit of detonation waves. They help to clear the flow dynamics of wave fronts, and refer suggestions for the formula of liquid explosives, study and application of equipment features. They help to improve and perfect the detonation theory. 

Over several decades, extensive research has been undertaken on the fundamental theory and the mechanisms involved in detonation. Extensive information on this research is in the literature [10]. But of the three fundamental combustion phenomena — deflagration, explosion, and detonation — only detonation has not found exploitation in practical civilian or military applications to the extent that this phenomenon warrants. This is partly due to the fact that the science and technology involved is very complex due to the intense and fast energy release rates and their interaction with the confinement prescribed by the... 

Detonation, Transducers Application in Phenomena of. See Refs 74 77 under DETONATION (AND EXPLOSION), EXPERIMENTAL PROCEDURES IN... 

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