Low-velocity detonation limits of gaseous mixtures

Manzhalei, V. I.

doi:10.1007/bf02674453

Cited by 34 publications

(14 citation statements)

References 2 publications

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“…From Figure 7 it is evident that as the turbulent flame caught up with the shock wave, a retonation wave propagating towards the burnt side of the flame front formed at 10.85 m. The velocity of the retonation wave ranged from 1085 to 1475 m s 1 , with an average of 1280 m s 1 . The average velocity in EPM/air was 1415 m s 1 [29], whereas no retonation wave formed in FAD/air, nitromethane mist/air and nitromethane mist/FAD/air mixtures [19,20]. At 12.25 m a critical SRC formed, characterized by the Mach number 5.2 and the overpressure >1.7 MPa.…”

Section: Ddt Process In Sad/epm/air Mixture Cloudsmentioning

confidence: 96%

“…A lower speed limit of the shock velocity for a quasi-detonation wave can be obtained by assuming that the wave structure begins with a shock-front propagation at a critical velocity D cr and ends with an equilibrium constant volume explosion boundary at the sonic plane [28,29]. The constant volume explosion implies a zero absolute flow velocity.…”

Section: Regimes Of Wave Propagation In Combustible Mixturesmentioning

confidence: 99%

“…A typical pressure profile at the gauge position in the detonation section is shown in Figure 9. The average period of the pressure wave oscillation after the shock front was ~0.242 ms and thus the cell size of the detonation was 0.423 m. The parameters for the five DDT stages are compared for EPM/air [29], SAD/air and SAD/EPM/air in Table 1.…”

Section: Ddt Process In Sad/epm/air Mixture Cloudsmentioning

confidence: 99%

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Deflagration-to-detonation transition process for spherical aluminum dust/epoxypropane mist/air mixtures in a large-scale experimental tube

Liu

Chen

et al. 2011

Sci. China Phys. Mech. Astron.

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The deflagration-to-detonation transitions (DDTs) for clouds of spherical aluminum dust (SAD) mixed with air or epoxypropane mist (EPM) and air were investigated in a 29.6-m-long experimental tube of 199 mm in diameter. The clouds formed through the injection of SAD and SAD/liquid epoxypropane samples into the experimental tube. Explosions of the SAD/air mixture were initiated using a 7-m-long EPM/air cloud explosion ignited by a 40-J electric spark. Explosions in SAD/EPM/air clouds were initiated using a 1.2-m EPM/air cloud explosion ignited by a 40-J electric spark initiated using a 40-J electric spark. Self-sustained detonation waves formed in SAD/EPM/air mixtures instead of in SAD/air mixtures. The stages and characteristics of the DDT process in SAD/air and SAD/EPM/air mixtures were studied and analyzed. Self-sustained detonation was evident from the existence of a transverse wave and a cellular structure. Moreover, a retonation wave formed during the DDT process in SAD/EPM/air clouds. deflagration-to-detonation transition, spherical aluminum dust, epoxypropane mist, multiphase explosion, experimental tube

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Section: Ddt Process In Sad/epm/air Mixture Cloudsmentioning

confidence: 96%

Section: Regimes Of Wave Propagation In Combustible Mixturesmentioning

confidence: 99%

Section: Ddt Process In Sad/epm/air Mixture Cloudsmentioning

confidence: 99%

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Deflagration-to-detonation transition process for spherical aluminum dust/epoxypropane mist/air mixtures in a large-scale experimental tube

Liu

Chen

et al. 2011

Sci. China Phys. Mech. Astron.

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“…The distance to the point of flow stoppage behind the basic shock wave was obtained from the condition of identical mass fluxes through the basic shock wave and the into the "layer" of ribs of length x: Allowance for the burning rate of the C 2 H 2 + 5O 2 mixture at a distance x ∼ = x(1−υ/u) between the shock wave and the flame reduces this distance to (1.28-1.04)h within the range, which almost coincides with the experiment (here u is the gas velocity with respect to the basic shock wave, υ = υ 0 T 2 /T 2 0 is the flame velocity with respect to the gas [7], T is the temperature ahead of the flame, and υ 0 = 9 m/sec is the laminar flame velocity at room temperature T 0 in the C 2 H 2 + 5O 2 mixture [3,8]). Some difference may be caused by the neglect of flame turbulization by shock waves reflected from the ribs.…”

Section: Approximate Calculationsmentioning

confidence: 97%

“…Its velocity is (0.4-0.55)D 0 , where D 0 is the velocity of ideal detonation without losses [1][2][3]. When the core flow is decelerated behind the shock wave owing to gas outflow to a viscous boundary layer on the tube wall, the flame is maintained at a distance of several channel diameters from the shock wave [1][2][3]. The flame stays at a point where the gas velocity in the core flow equals the normal velocity of the flame in the shock-wave-fitted system.…”

Section: Introductionmentioning

confidence: 99%

Gas detonation in a channel with transverse ribs

Manzhalei

2007

Combust Explos Shock Waves

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Results of experiments on detonation propagation in a rectangular horizontal channel with high ribs on the lower wall are presented. The experiments were performed with acetylene-oxygen mixtures. An interval of initial pressures is found, in which low-velocity detonation with a steady velocity of 0.38-0.55 of the Chapman-Jouguet velocity without losses exists. This detonation wave is a system consisting of a shock wave and a flame. Owing to gas outflow to the layer occupied by the ribs, the flame is maintained at a constant distance from the shock wave, which is approximately equal to the free transverse size of the channel. This distance weakly decreases with increasing initial pressure and is almost independent of the burning rate of the gas at standard temperature.

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Effect of Temperature, Density and Confinement on Deflagration to Detonation Transition of an HMX‐Based Explosive

Dai

Wen

Huang

et al. 2014

Propellants Explo Pyrotec

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In order to obtain the characteristics of the deflagration‐to‐detonation transition (DDT) of PBX‐2 (an HMX‐based explosive) under different conditions, DDT tests were carried out as a function of charge density, temperature, and shell confinement. In these tests, the energetic materials were electrically ignited. The DDT response characteristics for PBX‐2 with 53 % and 99 % of theoretical maximum density (TMD) were evaluated by different shell thickness confinements at ambient temperature and at 85 °C. The test results with different densities, confinements and temperatures exhibited a wide range of reaction violence. Firstly, at both ambient temperature and at 85 °C under 10 and 20 mm shell thickness confinement, PBX‐2 did not undergo fully DDT at 99 % TMD, only a low velocity detonation (LVD) occurred. Secondly, PBX‐2 at 53 % TMD underwent DDT, and significant influence on the minimum run distance to detonation by the shell confinement thickness was observed. Strong confinement is favorable for the transition of DDT but the confinement does not influence reaction degree. Thirdly, the reaction degree of PBX‐2 at 85 °C was remarkably lower than that at ambient temperature. This insensitizing effect of temperature is induced by the melting and flowing of bonders which reduces the porosity and inhibits an important step of DDT, namely, high turbulent combustion.

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Low-velocity detonation limits of gaseous mixtures

Cited by 34 publications

References 2 publications

Deflagration-to-detonation transition process for spherical aluminum dust/epoxypropane mist/air mixtures in a large-scale experimental tube

Deflagration-to-detonation transition process for spherical aluminum dust/epoxypropane mist/air mixtures in a large-scale experimental tube

Gas detonation in a channel with transverse ribs

Effect of Temperature, Density and Confinement on Deflagration to Detonation Transition of an HMX‐Based Explosive

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