Criterion of shockwave initiation of detonation in solid explosives. The leading shock compresses the highexplosive material, and converts the highexplosive into. The present work builds on earlier work by jackson et al. This is a compilation of published detonation velocities for various high explosive compounds. Detonation propagation for shockdriven, subsonic and supersonic confiner. It is a key, directly measurable indicator of explosive performance, but depends on density which must always be specified, and may be too low if the test charge diameter is not. Explosive velocity, also known as detonation velocity or velocity of detonation vod, is the velocity at which the shock wave front travels through a detonated explosive. These explosives are often heterogeneous in their composition. Pressure in the detonation reaction zone as it progresses along a charge, expressed in mpa.
When a shockwave is created by high explosives such as tnt which has a detonation velocity of 6,900 ms, it will always travel at high, supersonic velocity from its point of origin. Detonation wave profiles in hmx based explosives unt. Detonation blast pressures of tnt and c4 at 100 degrees c. A detonation will also cause a shock of type 1, above to propagate into the. Le create a subsonic explosion and lack hes over pressurization wave. Subsonic mshigh speed shock wavehigh explosives detonation. Prediction of detonation pressure of condensed explosives at various initial densities by simple procedure is an important problem. What is the difference between deflagration combustion and. High explosives, such as c4 and tnt, expand more rapidly, generating much greater pressure. Experimental observations of detonation in ammoniumnitrate. Military applications are excluded from this discussion. Accurate prediction of nonideal high explosive nihe detonation has become a topic of signi cant interest in recent years.
Le create a subsonic explosion and lack hes overpressurization wave. The paper aims to theoretically and numerically investigate the confinement effect of inert materials on the detonation of insensitive high explosives. Bow shock detached shock these shocks are curved and form a small distance in front of the body. Criterion of shockwave initiation of detonation in solid. The fundamental concept behind explosives is very simple. Detonation, on the other hand, occurs when an exothermic reaction accelerates through the material at supersonic speeds, creating a shock wave an advancing area of extreme pressure in front of it. Plot of pressure versus distance for a detonation wave. Is the most powerful and brisant of the military high explosives. Explosives experts refer to rapid explosive reactions as detonation and slower explosive reactions as deflagration. In contrast, for the anfoal interaction here and in the limit where the detonation relaxes to a quasisteady propagation, the flow in the wall is shockless and subsonic and hence the detonation reaction zone, and thus detonation speed, should respond to any increase in the wall thickness regardless of how thick the wall is.
Pdf detonation blast pressures of tnt and c4 at 100. The force of the action required to cause detonation depends on the chemical nature of the explosive. Detonation of anfo without a secondary explosive booster. A general theory of explosives is that the detonation of the explosives charge causes a high velocity shock wave and a tremendous release of gas. Im what they call an expert in military explosives. It is a key, directly measurable indicator of explosive performance, but depends on density which must always be specified, and may be too low if the test charge diameter is not large enough. There is always the possibility of the detonation of explosives containing nitroglycerine, which have a relatively high sensitivity to a large number of forms of energy. In explosives, it is not clear if the nanoparticles are small enough to react faster than micrometric particles and, therefore, to participate in the detonation reaction zone. Think texas city disaster bp just doesnt have the combustion temps to trigger detonation in anfo, let alone straight an.
Reaction zones of detonating solid explosives springerlink. Explosives that work by deflagration are usually termed the low explosives. Deflagration and detonation are two ways energy may be released. Instead, the ow in the con ner is shockless and subsonic in the frame of the detonation. In the case of an aircraft travelling at high subsonic speed, regions of air around. Shockinduced detonation of high explosives by high. Detonation propagation for shockdriven, subsonic and supersonic. If the explosion moves outward at supersonic speeds faster than the speed of sound, its a detonation. Thus, the detonation wave is a shock wave in a reactive medium that is sustained by the. Prediction of detonation pressure and velocity of explosives. At the most basic level, an explosive is just something that burns or decomposes very quickly, producing a lot of heat and gas in a short amount of time a typical explosive consists of some explosive material, some sort of detonation device and, typically, some sort of housing. Trace fire and safety consultants, ltd is a consulting firm that provides investigative and consultative services in the areas of fire, arson and explosion investigation, safety auditing and managment, industrial accident investigation and osha.
Detonations occur in both conventional solid and liquid explosives, as well as in reactive gases. Rodriguez chemistry of high energy materials baran gm 20120818 routes tto cnitro functionality nitration chemistry borgardt et al. In recent years, high quality data from experiments using embedded gauges and other diagnostic techniques have inspired the development of a range of new highfidelity computer models for explosives. The shock wave, at the right, is the leading element of the detonation wave. These cracks are then filled with the expanding gases. In physics, a shock wave also spelled shockwave, or shock, is a type of propagating.
High explosives do not need to be confined to function. The flow field can be approximated as a lead shock wave, followed by a selfsimilar subsonic flow. Due to their low detonation speed, nonideal detonations con ned by metals often propagate slower than the sound speed in the con ner. The shock and detonation response of high explosives has been an active research topic for more than a century. Directly in front of the body, they stand at 90 degrees to the oncoming flow.
Monterey, california i the detonation of solid explosives by chester arthur zimmerman a thesis presented to the graduate faculty of lehigh university in candidacy for the degree of master of science lehigh university 1952 ii this thesis is accepted and approved. Dynamics of high soundspeed metal con ners driven by non. The leading shock compresses the high explosive material, and converts the highexplosive into. In fluid dynamics, a blast wave is the increased pressure and flow resulting from the deposition of a large amount of energy in a small, very localised volume. Shockwave eyewitness accounts suggest the pentagon attack involved explosive detonation many of the over 100 eyewitness accounts in eric barts compilation recall characteristics of the explosion that accompanied the september 11th attack on the pentagon that are suggestive if not conclusive of the detonation of a powerful explosive device. The vod range in commercial explosives is 25007500 ms.
Tarver, a statistical hotspot reactive flow model for shock initiation and detonation of solid high explosives, in twelfth international detonation symposium office of naval research, 2002, vol. Detonation article about detonation by the free dictionary. Sciencemadness discussion board flash powder detonation. A detonation is characterized by supersonic flame propagation velocities, perhaps up to 2000 ms, and substantial overpressures, up to 20 bars. On the other hand, secondary explosives, or high explosives are less sensitive, but usually more powerful.
Scope tnt and c4 were tested at core temperatures of 8 5 f 30 c and. Understanding the shock and detonation response of high. The heat released by the reactions supports the propagation of the shock wave. Types of low explosives black powder and smokeless poweder. A simple relation between the detonation velocity of an. Belskii, excitation of detonation process in solid heterogeneous explosives by pulse loads vniief, arzamas16, 1993. Reports of premature initiation of electric detonators by. When a shockwave is created by high explosives such as tnt. May 04, 2007 what marine recruits go through in boot camp earning the title making marines on parris island duration. High explosives that detonate generate blast waves. When a shock wave is created by high explosives such as tnt which has a detonation velocity of 6,900 ms, it will always travel at high, supersonic velocity from its point of origin. Detonation parameters of some selected high explosives. In an explosive charge, detonation creates an intense mechanical or thermal action shock, spark discharge, or explosion of a metal wire by an electric current.
Detonation of anfo without a secondary explosive booster charge. Numerical modelling of steady detonations with the crest reactive. Its followed by a zone of explosive material which is undergoing an exothermic chemical reaction. A mixture of petn and etn all in all 200g was detonated with a remote control system and a hmtd blasting cap. Pdf the propagation of detonation waves in nonideal condensed. Based on their sensitivity, explosives can be categorized into primary and secondary explosives. A detonation wave is essentially a shock supported by a trailing exothermic reaction.
The propagation of detonation waves in nonideal condensed. High vod explosives are more suitable in hard rock and low vod in softer rock. Experimental observations of detonation in ammonium. Detonation velocity is the speed with which the detonation shock wave travels through the explosive. The detonation velocity for the mixed explosives can be estimated by a similar pathway to the detonation pressure.
A particular focus of this prior work was the effect of the highsoundspeed aluminum confinement on the shape. Table of explosive detonation velocities wikipedia. Trace fire and safety trace fire protection and safety. Chno explosives, predicting the detonation velocity of. A deflagration is characterized by a subsonic flame propagation velocity, typically far below 100 metres per second 220 mph, and relatively modest overpressures, say below 0. Explosives are categorized as highorder explosives he or loworder explosives le. The shock wave cracks and crushes the rock near the explosives and creates thousands of cracks in the rock. High explosive detonationconfiner interactions annual. Mar 24, 20 a mixture of petn and etn all in all 200g was detonated with a remote control system and a hmtd blasting cap. Prediction of detonation pressure and velocity of xplosives 83 can be obtained when p emaxi is known. The calculations rely on classical results of detonation theory, linked to the assumption of adiabatic expansion of the gaseous detonation products. Generally, explosives with a lower vod tend to release gas over a longer period and consequently have more heave. Emissions associated with the manufacture of explosives are treated in section 6. Detonation temperature is one of the detonation parameters with least information in the cj state which is measured experimentally from the brightness of the.
Impact of a shock wave on a structure on explosion at altitude. Highly nonideal condensedphase explosives used by the mining industry have. Nonideal explosives di er from conventional explosives in that they are usually highporosity, lowdensity materials where the fuel and oxidizer are not mixed on a molecular level. The explosive behind it, heated by the sudden compression, begins its chemical reaction there. In addition, it has been found in the literature that subsonic flow in the. Trinitrotoluene tnt, nitroglycerin ng and slurry explosives. If the combustion process propagates outward at subsonic speeds slower than the speed of sound, its a deflagration. How to explain the difference between deflagration and. Rodriguez chemistry of high energy materials baran gm 20120818 high energy materials explosives nonexplosive materials high explosives low explosives 1 explosives 2 explosives propellants pyrotechnics fireworks colorflashsound d e tonaby ig l eadzi tetrazene ned toartn rdx black powder liquidsolid. In this case, there is no shock polar solution at the high explosive hecon ner interface 20 4, 5, 6. Primary explosives are highly sensitive and easy to undergo the deflagrationtodetonation transition ddt. High temps above 1500f can cause anfo to detonate, as well as higher temps in the 2000f range can cause straight an to detonate.
A detonation consists of a shock wave sustained by the energy released due to a chemical reaction in an explosive material. Typical inelastic strain rates associated with permanent damage are of the order of 1100 sec1, with local rates at strain concentration sites corners, cracks, etc. The powders had 120 and 10 microm average grain sizes, respectively. Detonation from latin detonare, meaning to thunder downforth is a type of combustion involving a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. The calculations rely on classical results of detonation theory, linked to the assumption of adiabatic expansion of the. The data obtained have led to some conclusions on the regularities of he decomposition in a detonation wave. The velocity of detonation in solid and liquid explosives is much higher than that in gaseous ones. The detonation products are usually obtained at high. Dynamics of high soundspeed metal confiners driven by non. A detonation will also cause a shock of type 1, above to propagate into the surrounding air due to the overpressure induced by the explosion. A general theory of explosives is that the detonation of the explosives charge causes a highvelocity shock wave and a tremendous release of gas. What marine recruits go through in boot camp earning the title making marines on parris island duration. The data listed for a specific substance is usually a rough prediction based upon gas behavior theory citation needed see chapmanjouguet condition, as in practice it is difficult to measure citation needed. High soundspeed confiners support the detonation through energy transport ahead of the detonation.
An improved shock polar theory based on the zeldovichvon neumanndoring model of explosive detonation is established and can fully categorize the confinement interactions between insensitive high explosive and inert materials into six types. Detonation temperature of high explosives from structural. Is the most powerful and brisant of the military high explosives reaches maximum pressure so rapidly that a shock wave formsreacts concentrated nitric acid with hexaminemust be used in conjunction with a detonator to produce an explosion. Experimental observations of detonation in ammoniumnitratefueloil anfo surrounded by a high soundspeed, shockless, aluminum con ner scott i. Attenuation of a shock wave in a pmma barrier placed behind a detonating. When a shock wave is created by high explosives such as tnt which has a. Detonation pressure and detonation velocity is much lower than those for infinite charge diameter. The primary purpose of a detonation in a high explosive he is to provide the energy to drive a surrounding confiner, typically for mining or munitions applications. Detonation wave profiles have been measured in several hmx based plastic bonded explosives including pbx9404, pbx9501, and edc37, as well as two hmx powders coarse and fine pressed to 65% of crystal density. Based on energetic considerations, we deduce a simple link between the detonation velocity d of an explosive and its gurney energy e g, namely. Can anfo be set off without a booster charge using low order explosives e. Simple method for predicting detonation pressure of chno. Planar detonations were produced by impacting the explosive with projectiles.
This makes absolute sense as there is no shock wave to speak of at subsonic speeds. Various pyrotechnic compositions were assessed in three experiments. Pdf equations of state and macrokinetics of decomposition of. The details of the interaction between an he detonation and its confinement are essential to achieving the objectives of the explosive device. The chemical reaction of the medium occurs following the shock wave, and the chemical energy of the reaction drives the wave forward. Subsonic explosive at greater than the speed of soundsupersonic ms high speed shock wave high explosives detonation. There have been early claims of improvements using nanopowders in explosives1,12. It involves a wave travelling through a highly combustible or chemically unstable medium, such as an oxygenmethane mixture or a high explosive. Burns rapidly, but only explode when confined in a container, often used as a propellant velocity of detonation deflagration less than. A detonation wave is a very sharp, very high pressure, shock wave travelling through an explosive material. Before that i was a mortarman, so know how shells work too.
My impression of what constitutes a detonation is a virtually instantaneous dissociation of a compound at the molecular level. Combustion burning is a process by which energy is released. The primary purpose of a detonation in a high explosive he is to provide the energy to. Those explosives are well known to show nonideal detonation behavior due to its slow reaction rate compared to high explosives for military use.
919 1249 209 1150 862 1423 1044 415 1119 525 1253 286 691 191 369 1507 1352 1472 1123 1185 1020 1142 1271 928 592 1293 1050 138 212