A weapons cache is detonated at the East River Range on Bagram Airfield, Afghanistan

Detonation is a process of supersonic combustion in which a shock wave is propagated forward due to energy release in a reaction zone behind it. Bagram Air Base is a militarized Airport and housing complex that is located next to the ancient city of Bagram, southeast of Charikar in Parwan Afghanistan /æfˈgænɪstæn/ officially the Islamic Republic of Afghanistan ( Pashto: د افغانستان اسلامي جمهوریت, Combustion or burning is a complex sequence of Exothermic chemical reactions between a Fuel and an Oxidant accompanied by the production of For the music album by Converter see Shock Front For the 1977 horror film see Shock Waves A shock wave (also called It is the more powerful of the two general classes of combustion, the other one being deflagration. Combustion or burning is a complex sequence of Exothermic chemical reactions between a Fuel and an Oxidant accompanied by the production of Deflagration (Lat de + flagrare, "to burn down" is a technical term describing subsonic Combustion that usually propagates through Thermal conductivity In a detonation, the shock compresses the material thus increasing the temperature to the point of ignition. The ignited material burns behind the shock and releases energy that supports the shock propagation. This self-sustained detonation wave is different from a deflagration, which propagates at a subsonic speed (i. The Chapman-Jouguet condition holds approximately in Detonation waves Deflagration (Lat de + flagrare, "to burn down" is a technical term describing subsonic Combustion that usually propagates through Thermal conductivity e. , slower than the sound speed of the explosive material itself), and without a shock or any significant pressure change. Sound is a vibration that travels through an elastic medium as a Wave. Because detonations generate high pressures, they are usually much more destructive than deflagrations.

The simplest theory to predict the behavior of detonations in gases is known as Chapman-Jouguet (CJ) theory, developed around the turn of the 20th century. The Chapman-Jouguet condition holds approximately in Detonation waves This theory, described by a relatively simple set of algebraic equations, models the detonation as a propagating shock wave accompanied by exothermic heat release. Such a theory confines the chemistry and diffusive transport processes to an infinitely thin zone.

A more complex theory was advanced during World War II independently by Zel'dovich, von Neumann, and Doering. Yakov Borisovich Zel'dovich (Яков Борисович Зельдович ( March 8, 1914 &ndash December 2, 1987) was a prolific Soviet This theory, now known as ZND (explosion) theory, admits finite-rate chemical reactions and thus describes a detonation as an infinitely thin shock wave followed by a zone of exothermic chemical reaction. In the reference frame in which the shock is stationary, the flow following the shock is subsonic. Because of this, energy release behind the shock is able to be transported acoustically to the shock for its support. For a self-propagating detonation, the shock relaxes to a speed given by the Chapman-Jouguet condition, which induces the material at the end of the reaction zone to have a locally sonic speed in the reference frame in which the shock is stationary. The Chapman-Jouguet condition holds approximately in Detonation waves In effect, all of the chemical energy is harnessed to propagate the shock wave forward.

Both CJ and ZND theories are one-dimensional and steady. However, in the 1960s experiments revealed that gas-phase detonations were most often characterized by unsteady, three-dimensional structures, which can only in an averaged sense be predicted by one-dimensional steady theories. Modern computations are presently making progress in predicting these complex flow fields. Many features can be qualitatively predicted, but the multi-scale nature of the problem makes detailed quantitative predictions very difficult.

Detonations can be produced by high explosives, reactive gaseous mixtures, certain dusts and aerosols. An explosive material is a material that either is chemically or otherwise Energetically unstable or produces a sudden expansion of the material usually accompanied

Applications

Detonations are hard to control and are used primarily for demolition and in warfare. Demolition is the opposite of Construction: the tearing-down of Buildings and other Structures It contrasts with deconstruction War is an international relations Dispute, characterized by organized Violence between National Military units A great deal of research is conducted on achieving or preventing detonation in various materials to improve the performance of explosives and engines. Research is defined as Human activity based on Intellectual application in the investigation of Matter. An explosive material is a material that either is chemically or otherwise Energetically unstable or produces a sudden expansion of the material usually accompanied An experimental form of jet propulsion, the pulse detonation engine, uses a series of well-timed detonations to generate thrust. A pulse-detonation engine, or "PDE" is a type of propulsion system that can operate from subsonic up to Hypersonic speeds

Detonation in reciprocating engines is the uncontrolled supersonic explosion of the fuel-air charge, and is caused by excessively high combustion chamber temperatures. Knocking (also called knock, detonation or spark knock, pinking in UK English or pinging in US English in spark-ignition A reciprocating engine, also often known as a piston engine, is a Heat engine that uses one or more reciprocating Pistons to convert Increasing the temperature of the fuel-air charge increases the speed of combustion until the flame propagates at supersonic speeds, resulting in a pressure shockwave. This force is extremely destructive to common piston engines, and often results in holes blown through the top of pistons or cracks in cylinder heads. A piston is a component of Reciprocating engines Pumps and Gas compressors It is located in a cylinder and is made gas-tight by Piston In an Internal combustion engine, the cylinder head sits atop the cylinders and consists of a platform containing part of the Combustion chamber and the

References

For a good layman's introduction to the theory of detonation, see:

Davis, William C. , "The detonation of explosives," Scientific American, vol. 256, pages 106-112, 128 (May 1987).

Etymology

French détoner, to explode; from Latin detonare, to expend thunder; from de-, ~off + tonare, to thunder

See also

• Detonation section of Explosive, Detonator. An explosive material is a material that either is chemically or otherwise Energetically unstable or produces a sudden expansion of the material usually accompanied An explosive material is a material that either is chemically or otherwise Energetically unstable or produces a sudden expansion of the material usually accompanied For the Ratt album see Detonator (album A detonator is a device used to trigger an Explosive device.
• Nuclear testing
• Detonation diamond
• Predetonation of nuclear weapons
• Chapman-Jouguet condition