Detonation and deflagration initiation at the focusing of shock waves in combustible gaseous mixture

Gel’fand, B. E.; Khomik, S. V.; Bartenev, A. M.; Medvedev, S. P.; Grönig, Hans; Olivier, H.

doi:10.1007/s001930050007

Cited by 73 publications

(25 citation statements)

References 2 publications

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“…The shock structures produced by the rupture are affected by both the initial geometry of the burst disk at failure (multidimensional) and the (stochastic) fracture geometry, producing shocksidewall and shock-shock interactions (Jiang et al, 1997). It is possible through such shock interactions and ''shock focusing'' (Fay and Lekawa, 1956;Gelfand et al, 2000;Bartenev et al, 2001) exist and produce higher local temperatures and pressures (and hence shorter ignition delays) than those estimated on the basis of simple 1-D theory. Moreover shock interactions with the side walls of the cavity will result in heating the air in the developing boundary layers near the walls and in increasing contact surfaces between the expanding hydrogen core and shock-heated air.…”

mentioning

confidence: 99%

Spontaneous Ignition of Pressurized Releases of Hydrogen and Natural Gas Into Air

Dryer

Chaos

Zhao

et al. 2007

Combustion Science and Technology

188

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This paper demonstrates the ''spontaneous ignition'' (autoignition=inflammation and sustained diffusive combustion) from sudden compressed hydrogen releases that is not well documented in the present literature, for which little fundamental explanation, discussion or research foundation exists, and which is apparently not encompassed in recent formulations of safety codes and standards for piping, storage, and use of high pressure compressed gas systems handling hydrogen. Accidental or intended, rapid failure of a pressure boundary separating sufficiently compressed hydrogen from air can result in multi-dimensional transient flows involving shock formation, reflection, and interactions such that reactant mixtures are rapidly formed and achieve chemical ignition, inflammation, and transition to turbulent jet diffusive combustion, fed by the continuing discharge of hydrogen. Both experiments and simple transient shock theory along with chemical kinetic ignition calculations are used to support interpretation of observations and qualitatively identify controlling gas properties and geometrical parameters. Although the phenomenon is demonstrated for pressurized hydrogen burst disk failures with different internal flow geometries, similar phenomena apparently do not necessarily occur for sudden boundary failures potential for producing ignition and continuing combustion. Much more experimental and computational work is required to quantitatively determine the envelope of parameter combinations that mitigate or enhance spontaneous ignition characteristics of compressed hydrogen as a result of sudden release, particularly if hydrogen is to become a major energy carrier interfaced with consumer use. Similar considerations for compressed methane, for mixtures of light hydrocarbons and methane (simulating natural gas), and for larger carbon number hydrocarbons show similar autoignition phenomena may occur with highly compressed methane or natural gas, but are unlikely with higher carbon number cases, unless the compressed source and=or surrounding air is sufficiently pre-heated above ambient temperature. Spontaneous ignition of compressed hydrocarbon gases is also generally less likely, given the much lower turbulent blow-off velocity of hydrocarbons in comparison to that for hydrogen.

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mentioning

confidence: 99%

Spontaneous Ignition of Pressurized Releases of Hydrogen and Natural Gas Into Air

Dryer

Chaos

Zhao

et al. 2007

Combustion Science and Technology

188

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“…The reflection of shock waves from shock tube end walls is a well-established method of initiation [3,4] and is the primary technique used to measure ignition delay times. Several studies have also shown that reflection of a planar incident shock wave from a concave end wall will focus the reflected wave [5][6][7][8], and that the temperatures and pressures at the gas-dynamic focus can be sufficient for initiation of the postshock mixture [9][10][11][12][13][14]. Toroidally imploding shock waves have also been directly initiated from ring sources [15].…”

Section: Previous Research On Imploding Wavesmentioning

confidence: 99%

Detonation Initiation in a Tube via Imploding Toroidal Shock Waves

Jackson

Shepherd

2008

AIAA Journal

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The effectiveness of imploding waves at detonation initiation of stoichiometric ethylene-and propane-oxygennitrogen mixtures in a tube was investigated. Implosions were driven by twice-shocked gas located at the end of a shock tube, and wave strength was varied to determine the critical conditions necessary for initiation as a function of diluent concentration for each fuel. Hydrocarbon-air mixtures were not detonated due to facility limitations, however, detonations were achieved with nitrogen dilutions as large as 60 and 40% in ethylene and propane mixtures, respectively. The critical-energy input required for detonation of each dilution was then estimated using the unsteady energy equation. Blast-wave initiation theory was reviewed and the effect of tube wall proximity to the blast-wave source was considered. Estimated critical energies were found to scale better with the planar initiation energy than the spherical initiation energy, suggesting that detonation initiation was influenced by wave reflection from the tube walls.

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“…The shock focusing in the symmetric inner double wedge was first discussed by Milton [13] in 1989 and was used to ignited the quiescent, combustible mixtured gas by Gelfand [7] in 2000.…”

Section: Shock Focusing and Ignition By Shock Focusing In Symmetric mentioning

confidence: 99%

“…The shock focusing, acting as an ignition method to ignite the combustible gas premixed, has attracted much attention of researchers in recent years, such as the work done by Borisov et al [4][5][6][7][8][9]. Compared to other ignition method, the ignition by the shock focusing has particular advantage, which is potential in some special situation.…”

Section: Introductionmentioning

confidence: 99%

Investigation of high-speed combustible gas ignited by a hot gas jetproduced in the shock tube

Wang

Han

Situ³

2006

Shock Waves

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The high-speed combustible gas ignited by a hot gas jet, which is induced by shock focusing, was experimentally investigated. By use of the separation mode of shock tube, the test section of a single shock tube is split into two parts, which provide the high-speed flow of combustible gas and pilot flame of hot gas jet, respectively. In the interface of two parts of test sections the flame of jet was formed and spread to the high-speed combustible gas. Two kinds of the ignitions, 3-D "line-flame ignition" and 2-D "plane-flame ignition", were investigated. In the condition of 3-D "lineflame ignition" of combustion, thicker hot gas jet than pure air jet, was observed in schlieren photos. In the condition of 2-D "plane-flame ignition" of combustion, the delay time of ignition and the angle of flame front in schlieren photos were measured, from which the velocity of flame propagation in the high-speed combustible gas is estimated in the range of 30-90 m/s and the delay time of ignition is estimated in the range of 0.12-0.29 ms.

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Detonation and deflagration initiation at the focusing of shock waves in combustible gaseous mixture

Cited by 73 publications

References 2 publications

Spontaneous Ignition of Pressurized Releases of Hydrogen and Natural Gas Into Air

Spontaneous Ignition of Pressurized Releases of Hydrogen and Natural Gas Into Air

Detonation Initiation in a Tube via Imploding Toroidal Shock Waves

Investigation of high-speed combustible gas ignited by a hot gas jetproduced in the shock tube

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