Combustion modes and flame propagation criteria for an encumbered space

The topic is analyzed. Experiments have been performed with fuel—air mixtures in a porous medium. Measurements have been made on the velocity and pressure in the detonation and combustion waves, together with the critical initial parameters and the limits to the Peclet number. The mean detonation rate has been found to fall and the ignition has been found to be retarded in a porous medium when the wave passes through a free gap.Combustion and Flame Institute, Siberian Branch, Russian Academy of Sciences, Novosibirsk 630090. Translated from Fizika Goreniya i Vzryva, Vol. 30, No. 4, pp. 52–60, July–August, 1994.     

Detonation of Secondary Explosives in a Vacuum Suspension

The existence of self–sustaining detonation in an evacuated suspension of the particles of a secondary explosive is shown experimentally. The experiments with HMX were performed in a vertical shock tube of diameter 0.07 m and length 7 m in the range of volume–average particle concentrations 0.32—0.9 kg/m³. It is shown that the vacuum–detonation velocity does not almost depend on the volume–average concentration of particles and it is (1750±50) m/sec and that the pressure profile of a vacuum–detonation wave is smooth. The data on the electric conductivity of vacuum–detonation products and the length of the reaction zone are given.     

Formation of carbon clusters in deflagration and detonation waves in gas mixtures

Numerical and experimental results of studying the formation of carbon clusters due to propagation of deflagration and detonation waves in enriched acetylene-oxygen and acetylene-air mixtures are described. Experiments are performed in tubes of different diameters (including tubes filled by a porous medium) with wide-range variations of the initial pressure and the fuel-to-oxidizer ratio. A large variety of carbon clusters formed in different regimes of burning of the mixture is found. A typical size of condensed carbon particles is 15–100 nm. In the case of detonation in a porous medium, the size of carbon particles is 15–45 nm; in some tests, large individual fullerene-type particles 150, 400, and 950 nm in size are formed. The fraction of condensed carbon in the total amount of carbon in the initial mixture is found to depend on the wave type; detonation is characterized by the minimum “yield” of condensed carbon. The amount of condensed carbon increases with increasing acetylene concentration in the mixture and initial pressure. The size of carbon particles in the case of deflagration is greater than that in the case of detonation. Cooling of reaction products decelerates condensation and interrupts the growth of carbon particles. __________ Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 3, pp. 81–94, May–June, 2008.     

Standard reference exergies of chemical elements in the oceanic reference medium. II. Estimation of the equilibrium of ecospecies in the oceanic medium

A refined system (set), as compared to the Ocean-1 and Ocean-2 systems, of equilibrium standard reference exergies of chemical elements, called the Ocean-3 system, has been developed. The exergies forming the Ocean-3 system were calculated with account for the large oceanic ionic-ligand equilibrium between all chemical elements present in the oceanic medium involving about 300 reactions of complexation of elements. The independence of the equilibrium standard reference exergy of an element of its representative ecospecies was substantiated theoretically and supported by a concrete calculation. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 5, pp. 190–199, September–October, 2006.     

Bubble detonation conditions

Initiation of bubble detonation in the system “inert liquid-explosive gas bubbles” by a detonation wave in a gas was studied experimentally. Compression-wave pressure profiles were determined as functions of the length of the initiation section and the initial pressure of the explosive gas mixture in it. It was shown that because of the effect of the explosive-gas volume between the diaphragm and the upper boundary of the bubble medium, the pressure in front of the initiating wave increased much more slowly than the initial pressure. The optimal length of the initiation section was found, and the critical (minimum) initiation pressure in it and at the shock-wave front were determined. It was found that for a fixed gas volume concentration in the bubble medium, the pressure in the initiation section increased insignificantly as the length of the section decreased. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 2, pp. 84–90, March–April, 2007.     

Mass Transfer of Lead Coolant Vapors in a BREST-OD-300 Reactor

The goal of the work reflected in this paper is to investigate the mass transfer of lead from the coolant surface in the gaseous cavities of the cooling loop of a BREST-OD-300 reactor. The theoretical and experimental investigations show that the amount of lead evaporating from the free surfaces of the first loop of the reactor is negligible.The results of this work are the recommendations that filters should be placed at locations where the pipelines of the gas system, located outside the reactor block, are connected to the reactor cover, because of the possibility of aerosols – dust-like impurities from other sources with mass flow several times greater than the rate of evaporation of lead in the unit – entering the gas system. 2 figures, 7 references.     

High-temperature gasification of carbon-containing raw materials with the use of electric-arc energy and calorific capacity of the gas fuel

Disposal of carbon-containing wastes in a plasma furnace is studied. The influence of the plasma generator power on gasifier efficiency is found for different waste humidities; dependences of specific energy consumption on the waste humidity and air flow rate are obtained. Experimental results are in good agreement with calculations. Sawdust gasification is performed in an electric-arc furnace with an additional heater. The composition of the resultant synthesis gas is analyzed, and the heater performance is determined. It is demonstrated that burning some part of the resultant gas in the heater allows energy consumption to be reduced by 20–25%, as compared with purely plasma gasification.     

The influence of longitudinal magnetic field on recombination radiation of low-pressure glow discharge in hydrogen and helium

We study the influence of longitudinal magnetic field on the radiation of low-pressure glow discharges in hydrogen and helium. We conducted experiments under a pressure in a discharge chamber of 10–20 Pa and a discharge current of 10–20 mA. A 0–1600 G magnetic field influenced only the cathode parts of the discharge, negative glow, and the dark Faraday space. The electron temperature and density were measured by the two-probe method as a function of magnetic field. We studied the dependence of the intensity of radiation in the spectral lines and continuous spectrum on magnetic field induction. We discovered that, under the action of magnetic field, discharge in hydrogen and helium is compressed and its glow volume increases by a factor of 20–25. In contrast, the radiation intensity in the lines and continuous spectrum increase by a factor of 100–200. We found a strong discrepancy in the measured intensity of the continuous spectrum into spectral ranges with calculation of electron-ion recombination.