Transition from slow deflagration to detonation

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by
Commission of the European Communities , Luxembourg
StatementC. Koch, W. Drenckhahn.
SeriesNuclear science and technology
ContributionsDrenckhahn, W., Commission of the European Communities. Directorate-General for Science, Research and Development.
ID Numbers
Open LibraryOL21115668M
ISBN 100119396998

Cite this paper as: Drenckhahn W., Koch C. () Transition from Slow Deflagration to Detonation. In: Skupinski E., Tolley B., Vilain J. (eds) Safety of Thermal Cited by: 1. Simulation of the Transition from Deflagration to Detonation Auto-Ignition is a phenomenon that occurs in many practical combustion processes (engine knock, ignition in rapid compression machines or shock tubes etc).Cited by: deflagration, the leading shock and the reaction zone propagate at roughly the same speed [13].

After a flame had accelerated beyond a certain critical speed, a sudden jump in the flame speed to detonation velocity was observed. Assuming the final velocity of the detonation corresponds to the T.C. PZ7 PZ6 PZ5 PZ4 PZ3 PZ2 PZ1 Igniter. Key words: computational °uid dynamics, detonation phenomena, transition from de°a-gration to detonation AMS subject classi¯cation: 80A32, 76L05 1.

Introduction Spontaneous transition from de°agrative to detonative combustion, since its discovery more than a century ago by Bertholet and Vieille [1] and Mallard and LeChatelier [2], remainsCited by: 9. A detonation may form via direct initiation or deflagration-to-detonation transition (DDT).

The former mode is dependent upon an ignition source driving a blast wave of sufficient strength such that the ignitor is directly responsible for initiating the detonation.

The latter case begins with a deflagration initi. deflagration-to-detonation transition in terrestrial chemical systems and type Ia supernovae Alexei Y. Poludnenko1,2*, Jessica Chambers3, Kareem Ahmed3,Vadim N. Gamezo4, Brian 5 The nature of type Ia supernovae (SNIa)—thermonuclear explosions of.

slow deflagration-to-detonation transition upon ignition at a closed end of a tube is studied. The results obtained correspond in order of magnitude to experimental data. The modes of flame spread and the transition from deflagration to detonation (DDT) in gas-permeable, reactive granular materials have been the subject of extensive research--yet much remains to be understood.

Generally, the process begins with ignition. Alternatively, a detonation can be formed by indirect way, referring to the deflagration-to-detonation transition (DDT). It requires a weak ignition source and DDT is achieved after different stages of flame acceleration from slow burning to high speed turbulent deflagration, and eventually the detonation onset for various physical.

In some forms of supernovae and chemical explosions, a flame moving at subsonic speeds (deflagration) spontaneously evolves into one driven by a supersonic shock (detonation), vastly increasing the power output.

The mechanism of this deflagration-to-detonation transition (DDT) is poorly understood. Poludnenko et al. developed an analytical model to describe DDTs, then tested it.

Description Transition from slow deflagration to detonation FB2

An experiment is described in which velocity and pressure changes during the transition from slow burning to detonation in cast explosives are measured. A simple one‐dimensional physical model of explosive burning under confinement is assumed and used, in connection with experimental evidence, as the basis for a calculation of the time and distance necessary to start a shock in a.

An experiment is described in which velocity and pressure changes during the transition from slow burning to detonation in cast explosives are measured. A simple one-dimensional physical model of explosive burning under confinement is assumed and used, in connection with experimental evidence, as the basis for a calculation of the time and distance necessary to start a shock in a deflagrating.

Deflagration-to-detonation transition via the distributed photo ignition of carbon nanotubes suspended in fuel/oxidizer mixtures Combustion and Flame, Vol. No. 3 COMPUTATIONAL STUDY OF DEFLAGRATION TO DETONATION TRANSITION IN A STRAIGHT DUCT:.

Performance Impact of Deflagration to Detonation Transition Enhancing Obstacles [Paxson, Daniel E., Nasa Technical Reports Server (Ntrs), Et Al] on *FREE* shipping on qualifying offers. Performance Impact of Deflagration to Detonation Transition Enhancing ObstaclesAuthor: Daniel E.

Paxson. Deflagration to detonation transition in an enclosed rectangular laboratory scale explosion channel (GraVent facility, Technical University of Munich). Hydro. In all cases, fast deflagration-to-detonation transition occurs because of the formation of distributed ignition zones in reflections of a running shock wave formed by an accelerated flame.

Two well-known propagation mechanisms are deflagration (from slow deflagration to very fast deflagration) and detonation (achieved by direct induced detonation or via a deflagration to detonation transition). Extensive research after an accident is not always conclusive (see e.g.

HSE, ; for the Buncefield explosion). The deflagration-to-detonation transition in a mm square cross-section channel was investigated for a highly reactive stoichiometric hydrogen oxygen mixture at 70 kPa.

Obstacles of 5 mm width and 5, 10, and 15 mm heights were equally spaced 60 mm apart at the bottom of the channel.

The phenomenon was investigated primarily by time-resolved schlieren visualization from two orthogonal. Deflagration to detonation transition - Wikipedia Deflagration is subsonic combustion propagating through heat transfer; hot burning material heats the next layer of cold material and ignites it.

Most "fires" found in daily life, from flames to explosions such as that of black powder, are. Huahua Xiao, Elaine S.

Details Transition from slow deflagration to detonation EPUB

Oran, Flame acceleration and deflagration-to-detonation transition in hydrogen-air mixture in a channel with an array of obstacles of different shapes, Combustion and Flame, /tflame,(), ().

ignition in conjunction with deflagration-to-detonation transition (DDT) enhancing devices along the deflagration path. Numerous investigators have shown that these devices can reduce the DDT distance and time significantly, notably Shchelkin who pioneered the use of helical spirals along the bore of the detonation tube to promote DDT.

Peering inside the 'deflagration-to-detonation transition' of explosions 22 November Explosions of reactive gases and the associated rapid, uncontrolled release of large amounts of.

ABSTRACT. The numerical simulations on DDT (Deflagration-to-Detonation Transition) in the two-dimensional channel with the repeated obstacles using multi-step reaction model are performed for various BR values (Blockage Ratio: the value obtained by dividing the height of.

Download Transition from slow deflagration to detonation FB2

Deflagration to Detonation Transition. In some situations, a subsonic flame may accelerate into a supersonic flame. This deflagration to detonation is difficult to predict but occurs most often when eddy currents or other turbulence are present in the flames.

This can happen if the fire is partially confined or obstructed. Applications. 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 engines typically employ a Shchelkin spiral in the combustion chamber to facilitate the deflagration to detonation transition.

The mechanism has also found military use in thermobaric. The Shchelkin spiral is a device that assists the transition from deflagration (subsonic combustion) to detonation in a pulse detonation spiral is named after Kirill Ivanovich Shchelkin, a Russian physicist who described it in his book Gas Dynamics of Combustion.

In pulse detonation engines, direct detonation of the combustible mixture can be relatively straightforward, but. test bed The occurrence of detonation events was deter-mined by distinct marks left in the interior of the channel.

Distinct deflagrations were observed during the transition to detonation in PETN powders for a large range of initial bed packing densities and for. of fast deflagration, and its acceleration and transition to detonation in a 2D smooth tube filled by hydrogen-oxygen mixtures.

The numerical results show that fast deflagration is a self-sustained combustion wave, and the pressure plays an important role to. My name is Eric and I am working on valveless pulse detonation engine for my final year project.

I am trying to simulate the deflagration - to - detonation transition process with FLUENT. The model is a 2D, axisymmetric tube with one close end and the other end is set to ambient condition.

The potential for a deflagration to detonation transition (DDT) to occur in an unconfined vapor cloud explosion (VCE) with high reactivity flammable gases (e.g., ethylene, hydrogen, etc.) under conditions relevant to chemical processing and petroleum refining plants has.

Throughout the previous century, hydrocarbon-fueled engines have used and optimized the `traditional' combustion process called deflagration (subsonic combustion). An alternative form of combustion, detonation (supersonic combustion), can increase the thermal efficiency of the process by anywhere from 20 - 50%.

Even though several authors have studied detonation waves since the 's and a.Sulimov has been active in this area since the s when he co-authored the book entitled “Transition from Deflagration to Detonation in Condensed Phases.” This new book, on “Convective burning and low-velocity detonation of porous media” comprises an Introduction on the deflagration-to-detonation transition in solids.Grubelich, Mark C., Venkatesh, Prashanth B., Meyer, Scott E., & Bane, Sally P.M.

Deflagration-to-Detonation Transition in High Pressure Ethylene/Nitrous .