Detonation in a sensitive-explosive particle suspension number vacuum

Institute of Hydrology and Hydrotechnology, Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk. Translated from Fizika Goreniya i Vzryva, Vol. 30, No. 2, pp. 122–124, March–April, 1994.     

Explosive generation of heterogeneous detonation waves in aerocolloids of a unitary fuel

The process of explosive initiation of spherical, heterogeneous detonation waves in monodisperse, homogeneous aerocolloids of a unitary fuel is modeled mathematically. It is shown that regimes of decaying and detonating combustion of the reacting disperse mixtures are possible, depending on the initial mass concentration and initial particle size in the mixture. It is established that the laws governing the mass transfer of burning particles have a significant influence on the patterns of explosive generation and propagation of detonation waves in unitary fuel aerocolloids. The critical (maximum) diameter of the unitary fuel particles, below which the shock initiation of heterogeneous combustion is possible, is determined as a function of the particular value of their relative mass concentration in the mixture.Institute of Mechanics of Multiphase Systems, Siberian Branch of the Russian Academy of Sciences. Translated from Fizika Goreniya i Vzryva, Vol. 31, No. 3, pp. 83–91, May–June, 1995.     

Interaction of a shock wave with a cloud of particles

The present paper is devoted to experimental and theoretical investigation of shock-wave propagation in a mixture of a gas and solid particles with clearly defined boundaries of the two-phase region (cloud of particles). The effect of qualitative transformation of supersonic flow behind a shock wave in a cloud of particles is shown experimentally and substantiated theoretically for volume concentrations of the dispersed phase of 0.1–3%.Translated from Fizika Goreniya i Vzryva, Vol. 32, No. 2, pp. 86–99, March–April, 1996.     

Change in the structure of the filtration combustion wave due to a fuel composition change

Transition processes due to a sharp change in the amount of fuel in carbon/inert material mixtures in a filtration combustion wave with superadiabatic heating were studied theoretically and experimentally. It was found that transition from a lean mixture to a rich mixture, in which the thermal wave changes structure from normal to inverse, was accompanied by significant local heating, whereas in the reverse change in the composition, a temperature increase was not observed.     

Nonshock initiation of detonation in vacuum with unitary-fuel particles

The nonshock initiation of detonation in vacuum with unitary-fuel particles is considered. The dynamics of reaction-zone formation of a nonsteady detonation wave with disperse structure is discussed. The approach to steady Chapman—Jouquet detonation is considered. The critical initiation energies of a plane detonation wave with variation in length of the initiation section and the energy density supplied are calculated, and may be used in experimental investigations.Novosibirsk. Translated from Fizika Goreniya i Vzryva, Vol. 28, No. 4, pp. 136–142, July–August, 1992.     

Detonation burning of anthracite and lignite particles in a flow-type radial combustor

Regimes of continuous spin detonation of anthracite and lignite particles in an air flow in a radial vortex combustor 500 mm in diameter with a constant (along the radius) cross-sectional area are studied. Ground coal with a particle size of 1–12 μm is used. For transporting coal into the combustor and promoting the chemical reaction on the surface of solid particles, hydrogen or syngas is added in the ratio CO/H₂ = 1/1, 1/2, or 1/3. Continuous spin detonation of two-phase mixtures of fine anthracite and lignite particles and air with addition of hydrogen up to 4% of the coal consumption rate is obtained for the first time. The amount of syngas added to coal increases with decreasing fraction of hydrogen in the syngas: 14, 21, and 27% for anthracite and 11, 20, and 29% for lignite at CO/H₂ = 1/3, 1/2, and 1/1, respectively. The structure of detonation waves and the flow in their vicinity are not principally different from those observed previously for long-flame bituminous coal and charcoal. Higher detonation velocities are observed for more energy-intensive coal (anthracite). A higher pressure is obtained near the cylindrical wall of the combustor in cold runs as compared to detonation in the case with identical flow rates of the coal–air mixtures.     

Detonation of a mixture of RDX particles partially filling a cylindrical channel

Using a mathematical model of a two-phase, two-velocity medium, detonation in an annular layer of a suspension of volatile secondary explosives adjacent to the wall of a cylindrical channel is numerically investigated. The dynamics of formation and the special features of the structures of a two-dimensional reaction zone of a detonation wave in a gas mixture of RDX particles are discussed. A detonation regime with a vortex structure of the reaction zone is obtained in calculations for the first time. The geometrical limits of detonation in a channel are determined. Translated fromFizika Goreniya i Vzryva, Vol. 35, No. 4, pp. 79–87, July–August 1999.     

Electromagnetic wave absorption by an organic resin solution based on ferrite particles with a spinel crystal structure

We have investigated an organic resin solution designed for EM wave absorption based on a magnetic filler, composed of phases within the Mn_0.66Zn_0.27Fe_2.07O₄ system, embedded in an absorber composite with concentration ratios of 50:50, 75:25 and 90:10 by weight. The formation of the manganese zinc ferrite particles, as the principal magnetic phases, was achieved via the conventional ceramic method. The electromagnetic parameters of the composites were measured with a vector network analyser at 100 MHz to 10 GHz. The subject of the paper was a study of the electromagnetic absorber properties and the rheological properties of the resin composite based on ferrite particles with respect to using the materials in architectural coatings.     

Initiation of divergent detonation in a vacuum containing monofuel particles

The problem of impactless initiation of spherical and cylindrical detonation in a vacuum containing monofuel particles is formulated and solved numerically. Included in discussion are the dynamics and formation characteristics of the reaction zone for the divergent detonation waves with a dispersed structure. Critical initiation energies are determined as a function of the energy from the outside and of the dimensions of the region where that energy is released. Novosibirsk. Translated from Fizika Goreniya i Vzryva, Vol. 29, No. 5, pp. 66–71, September–October, 1993.     

Detonation front structure in condensed high explosives

Dzerzhinsk. Translated from Fizika Goreniya i Vzryva, Vol. 24, No. 1, pp. 95–99, January–February, 1988.     

生物质燃油碳烟颗粒的形貌、结构与组分表征

通过微乳化工艺分别把不同含量的精制生物质裂解油与柴油进行混合(micro-emulsified biomass fuel, MEBF), 研究了该类燃油碳烟颗粒的形貌与结构, 并对其组分进行了表征。结果表明:该类燃油碳烟的一次颗粒形貌均为球形, 而且一次颗粒之间互相连接构成链状团聚物。同时, 精制生物质裂解油含量为20%(质量)(BS20)的混合油碳烟颗粒的平均粒径最小, 约为32 nm, 其他含量混合油碳烟颗粒的平均粒径均在38 nm左右。BS30石墨化程度高于其余碳烟, 且BS20颗粒表面C=O和C-O-C基团含量较高, 可能归因于混合油燃烧过程中复杂含氧组分的氧化程度不同。     

Drag of nonspherical particles in a flow behind a shock wave

The early stage of velocity relaxation of nonspherical particles in a flow behind an incident shock wave is considered by the method of multiframe shadowgraphy. A procedure of processing the data on the motion of a free body for determining its acceleration is proposed; in combination with the diagnostic method used, the procedure forms something like a noncontact aerodynamic balance. Novel data on the drag of bodies of irregular shape in a flow behind a shock wave with Mach numbers of 0.5–1.5 and Reynolds numbers of 10⁵ typical of dust explosions are obtained. It is found that the values of drag of a nonspherical bluff body and a sphere under these conditions are similar and exceed the drag of a sphere in a steady flow by a factor of 2 to 3.Translated from Fizika Goreniya i Vzryva, Vol. 41, No. 1, pp. 81–88, January–February, 2005.     

Ignition of petn particles by a gas-detonation wave

Ignition ofPETN particles by a gas-detonation wave in a gas suspension has been studied experimentally. The critical pressure at which the total rate ofPETN decomposition increases sharply has been found using a method of multiwave pyrometry with variation in the pressure of the initial gas mixture from 0.1 to 0.4MPa. It is shown that this can occur owing to a large increase in thePETN surface area because of the fragmentation of melting particles in a high-enthalpy flow of gas. Lavrent’ev Institute of Hydrodynamics, Siberian Division, Russian Academy of Sciences Novosibirsk 630090. Translated from Fizika Goreniya i Vzryva, Vol. 33, No. 2, pp. 133–138, March–April, 1997.