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- Deflagration_to_detonation_transition abstract "Deflagration to detonation transition (DDT) refers to a phenomenon in ignitable mixtures of a flammable gas and air (or oxygen) when a sudden transition takes place from a deflagration type of combustion to a detonation type of combustion. The effects of a detonation are usually devastating.A deflagration is characterized by a subsonic flame propagation velocity, typically far below 100 m/s, and relatively modest overpressures, say below 0.5 bar. The main mechanism of combustion propagation is of a flame front that moves forward through the gas mixture - in technical terms the reaction zone (chemical combustion) progresses through the medium by processes of diffusion of heat and mass. In its most benign form, a deflagration may simply be a flash fire. In contrast, a detonation is characterized by supersonic flame propagation velocities, perhaps up to 2000 m/s, and substantial overpressures, up to 20 bars. The main mechanism of combustion propagation is of a powerful pressure wave that compresses the unburnt gas ahead of the wave to a temperature above the autoignition temperature. In technical terms, the reaction zone (chemical combustion) is a self-driven shock wave where the reaction zone and the shock are coincident, and the chemical reaction is initiated by the compressive heating caused by the shock wave.Under certain conditions, mainly in terms of geometrical conditions such as partial confinement and many obstacles in the flame path that cause turbulent flame eddy currents, a subsonic flame may accelerate to supersonic speed, transitioning from deflagration to detonation. The exact mechanism is not fully understood, and while existing theories are able to explain and model both deflagrations and detonations, there is no theory at present which can predict the transition phenomenon.A deflagration to detonation transition has been a feature of several major industrial accidents 1970 Propane vapour cloud explosion in Port Hudson The Flixborough disaster The 1989 Phillips Disaster in Pasadena, Texas The damage observed in the Buncefield fire, see the 2005 Hertfordshire Oil Storage Terminal fireThe 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.The mechanism has found military use in the thermobaric weapon.A deflagration to detonation transition (DDT) has also been proposed for thermonuclear reactions responsible for supernovae initiation; see also Carbon detonation.Apart from the name, this phenomenon is completely unrelated to the chemical combustion and flame acceleration phenomenon.".
- Deflagration_to_detonation_transition wikiPageExternalLink hsl02-02.pdf.
- Deflagration_to_detonation_transition wikiPageID "23375296".
- Deflagration_to_detonation_transition wikiPageRevisionID "601739105".
- Deflagration_to_detonation_transition hasPhotoCollection Deflagration_to_detonation_transition.
- Deflagration_to_detonation_transition subject Category:Combustion.
- Deflagration_to_detonation_transition subject Category:Explosives_engineering.
- Deflagration_to_detonation_transition subject Category:Industrial_fires_and_explosions.
- Deflagration_to_detonation_transition type Abstraction100002137.
- Deflagration_to_detonation_transition type Event100029378.
- Deflagration_to_detonation_transition type Fire107302836.
- Deflagration_to_detonation_transition type Happening107283608.
- Deflagration_to_detonation_transition type IndustrialFiresAndExplosions.
- Deflagration_to_detonation_transition type PsychologicalFeature100023100.
- Deflagration_to_detonation_transition type YagoPermanentlyLocatedEntity.
- Deflagration_to_detonation_transition comment "Deflagration to detonation transition (DDT) refers to a phenomenon in ignitable mixtures of a flammable gas and air (or oxygen) when a sudden transition takes place from a deflagration type of combustion to a detonation type of combustion. The effects of a detonation are usually devastating.A deflagration is characterized by a subsonic flame propagation velocity, typically far below 100 m/s, and relatively modest overpressures, say below 0.5 bar.".
- Deflagration_to_detonation_transition label "DDT (火薬学)".
- Deflagration_to_detonation_transition label "Deflagration to detonation transition".
- Deflagration_to_detonation_transition sameAs DDT_(火薬学).
- Deflagration_to_detonation_transition sameAs m.06w49xk.
- Deflagration_to_detonation_transition sameAs Q5251647.
- Deflagration_to_detonation_transition sameAs Q5251647.
- Deflagration_to_detonation_transition sameAs Deflagration_to_detonation_transition.
- Deflagration_to_detonation_transition wasDerivedFrom Deflagration_to_detonation_transition?oldid=601739105.
- Deflagration_to_detonation_transition isPrimaryTopicOf Deflagration_to_detonation_transition.