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When studying or discussing explosive safety, or the safety of systems containing explosives, the terms deflagration, detonation and deflagration-to-detonation transition (commonly referred to as DDT) must be understood and used appropriately to convey relevant information.
Detonation (from Latin detonare 'to thunder down/forth') [1] 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.
David Chapman [3] and Émile Jouguet [4] originally (c. 1900) stated the condition for an infinitesimally thin detonation. A physical interpretation of the condition is usually based on the later modelling (c. 1943) by Yakov Borisovich Zel'dovich, [5] John von Neumann, [6] and Werner Döring [7] (the so-called ZND detonation model).
Imprecise contact between the bridgewire and the primary explosive changes how quickly the explosive is heated up, and minor electrical variations in the wire or leads will change how quickly it heats up as well. The heating process typically takes milliseconds to tens of milliseconds to complete and initiate detonation in the primary explosive.
The phenomenon is exploited in pulse detonation engines, because a detonation produces a more efficient combustion of the reactants than a deflagration does, i.e. giving a higher yields. Such engines typically employ a Shchelkin spiral in the combustion chamber to facilitate the deflagration to detonation transition. [2] [3]
a small amount of a more powerful secondary explosive, directly in contact with the primary, and called "base" or "output" explosive, able to carry out the detonation through the casing of the detonator to the main explosive device to activate it. Explosives commonly used as primary in detonators include lead azide, lead styphnate, tetryl, and DDNP
If detonation is allowed to persist under extreme conditions or over many engine cycles, engine parts can be damaged or destroyed. The simplest deleterious effects are typically particle wear caused by moderate knocking, which may further ensue through the engine's oil system and cause wear on other parts before being trapped by the oil filter.
A flame arrester during testing A flame arrester made for a 91 cm (36 inch) pipe weighing 10 tons. A flame arrester (also spelled arrestor), deflagration arrester, [1] or flame trap [2] is a device or form of construction that will allow free passage of a gas or gaseous mixture but will interrupt or prevent the passage of flame.