Experimental investigation on the detonability of non-uniform gaseous mixtures

Sochet, Isabelle; Lamy, T.; Brossard, J.

doi:10.1007/s001930000066

Cited by 15 publications

(14 citation statements)

References 9 publications

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“…The complet experimental setup was already presented in a previous paper in case of the detonation process (Sochet, Lamy, & Brossard, 2000). The hemispherical charges (aqueous confinement) are formed on a horizontal plate (1.25!1.85 m) using metal rings (radius 0.03!R 0 !0.08 m).…”

Section: Methodsmentioning

confidence: 99%

Effect of the concentration distribution on the gaseous deflagration propagation in the case of H2/O2 mixture

Sochet

Gillard²,

Guélon³

2006

Journal of Loss Prevention in the Process Industries

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Section: Methodsmentioning

confidence: 99%

Effect of the concentration distribution on the gaseous deflagration propagation in the case of H2/O2 mixture

Sochet

Gillard²,

Guélon³

2006

Journal of Loss Prevention in the Process Industries

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“…The detonation regime of the explosion is obtained by the highly energetic electric discharge, which takes place at the centre of the bubble. Previous studies have shown that such an experimental device is adequate for the purposes of our studies and can be used successfully for the incident/reflected pressure predictions (Sochet, Lamy & Brossard, 2000). Observance of the Hopkinson scaling law allows one to deduce the pressure on a large-scale structure.…”

Section: Experimental Approachmentioning

confidence: 98%

Study of the explosion process in a small scale experiment—structural loading

Zyskowski¹,

Sochet²,

Mavrot

et al. 2004

Journal of Loss Prevention in the Process Industries

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“…Clearly enough, the dominant contribution comes from the difference in the fresh-components' enthalpies ∆h ∞ , which usually takes negative values. The evolution law (21) can be written as the differential equation (22) Its mathematical type can be identified by writing the shock-surface equation as x 3 = Ψ(x 1 , x 2 , t) with x k , k = 1,3 the space coordinates in the Laboratory frame. At an arbitrary instant of time t, the unit vector x 3 can always be chosen equal to the unit vector n normal to the shock, x 3 = n, D = D n, and so, using the identity κ = div n, we find that (22) is locally equivalent to 23Thus, the evolution law (22) is hyperbolic because V 2 is positive.…”

Section: The Large-activation-energy Analysismentioning

confidence: 99%

“…The state ahead of the detonation front in a pulsed detonation engine or in a high-speed combustor is also non-uniform because of the initiation and injection mechanisms and techniques. A few laboratory experiments have been carried out with initial gradients either parallel or normal to the propagation direction of the detonation [1,16,20,[22][23][24]. In particular, they point out the difficulty to have a good control of the initial gradients.…”

Section: Introductionmentioning

confidence: 99%

Critical Slow Dynamics of Detonation in a Gas with Non-Uniform Initial Temperature and Composition: A Large-Activation-Energy Analysis

Vidal

2009

International Journal of Spray and Combustion Dynamics

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We study the dynamic conditions of existence of the self-sustained detonation regime in gases with non-uniform initial temperature and dilution in the case where the gradients of initial state are parallel to the propagation direction. We analyze the slow dynamics of the detonation supposing that the initial variations have the same order of smallness as the unsteadiness and curvature of the leading shock of the detonation front. We obtain a hyperbolic evolution law for the detonation shock front as a solution to an eigenvalue problem solved in the asymptotic limit of large activation energies for which the induction time of the chemical decomposition process is considered much larger than the heat-release time. We study the effect of the shock dynamics of this self-sustained detonation front on the induction time and we integrate the evolution law for some examples of distinct or combined, dispersive or localized, initial variations in the temperature and diluent mass fraction. We show the existence of a bifurcation set of initial conditions that separates the self-sustained detonations that will continuously achieve the CJ regime from those whose dynamics eventually fail to initiate the chemical decomposition because the dynamic induction length becomes too long. We find that the characteristic critical lengths associated with the initial or boundary conditions are larger than the reference CJ characteristic chemical length by several orders of magnitude, a well-established experimental feature of gaseous detonations. We identify subcritical and supercritical limits which, respectively, give necessary and sufficient conditions for detonation. Below the subcritical limit, the combustion front cannot be coupled to the shock front because the volumetric expansion rate behind the shock is too large. Above the supercritical limit, the relaxation from an overdriven detonation regime to the self-sustained regime is a continuous process, without decoupling and recoupling of the combustion and shock fronts. We interpret the critical domain between these limits as the parametric zone in which experiments show successive decouplings and transverse recouplings of the combustion and shock fronts before the final self-sustained CJ regime.

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Experimental investigation on the detonability of non-uniform gaseous mixtures

Cited by 15 publications

References 9 publications

Effect of the concentration distribution on the gaseous deflagration propagation in the case of H2/O2 mixture

Effect of the concentration distribution on the gaseous deflagration propagation in the case of H2/O2 mixture

Study of the explosion process in a small scale experiment—structural loading

Critical Slow Dynamics of Detonation in a Gas with Non-Uniform Initial Temperature and Composition: A Large-Activation-Energy Analysis

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