20L近球形密闭罐内可燃气体流动和火焰传播的数值模拟

采用流体动力学计算软件-FLUENT数值模拟20 L近球形密闭罐进气流场,并分析进气位置、进气速度对进气流场的影响。结果表明:进气流速越大,密闭容器内的压强和气体湍流强度越大;当进气口直径与容器高度比值较小时,罐内压强、速度、湍流强度的最大值都位于进气口的轴线上,轴线左右两边的气体在不同时刻呈相同或相近的流态。模拟了可燃气体爆炸后火焰在罐内的传播过程,得到火焰以点火源为中心,以褶皱球形面向四周扩张,最后对模拟监测的压力值和实验压力传感器采集到的压力值进行比较。直观再现了20 L近球形密闭罐进气时气体扰动状况和近球形密闭罐中心点火的火焰传播过程。     

Initial stage of gas combustion in a closed volume

Combustion, Explosion, and Shock Waves -     

Ignition of a layer of combustible forest materials

Theoretical and experimental studies of the ignition of forest combustible materials by real ignition sources, which are modeled by a reference source, are reported. The time of ignition by the reference source is determined. The critical ignition energy is estimated, and its variation under real conditions is analyzed. Translated fromFizika Goreniya i Vzryva, Vol. 34, No. 6, pp. 14–22, November–December 1998. The paper is reported at the 2nd International Conference on Forest Fires (Irkutsk, 10–15 June, 1997).     

Raising the pressure in a closed volume during nonideal gas combustion

Moscow. Translated from Fizika Goreniya i Vzryva, Vol. 24, No. 2, pp. 19–26, March–April, 1988.     

Conditions of detonation initiation by focusing shock waves in a combustible gas mixture

Based on experiments on focusing shock waves in hydrogen-air mixtures and available publications, the critical shock-wave Mach number at which detonation is initiated near the apex of a concave reflector is analyzed as a function of the reflector size and reactivity of the mixture. The effect of the reflector shape and size on the value of this Mach number is studied. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 6, pp. 84–89, November–December, 2007.     

Ignition of a radiating gas by an incandescent surface

Conclusions The fundamental regularities of ignition of a radiating and absorbing gas by an incandescent surface are examined. In the case of an optically thin medium characteristic for high-temperature ignition, the problem is solved in the traditional stationary and nonstationary formulations [8]. It is shown that radiant heat transfer plays an essential part in the gas ignition process, in particular, the process can be accelerated and retarded in an optically thin gas medium because of radiant heat exchange. The case of an optically dense gasl _kb/l _o corresponds to radiant heat conduction, and therefore, does not result in a change in the ignition time but only to an increase in the scale of the lengthl _o. For intermediate values ofl _kb/l _o the dependence of on parameters governing the energetics of radiant heat transfer is complex in nature and can only be analyzed numerically in each specific case. The development of a suitable model of radiation heat exchange is the fundamental difficulty here.Minsk. Translated from Fizika Goreniya i Vzryva, Vol. 26, No. 1, pp. 15–21, January–February, 1990.     

Ignition of condensed substances in a hot gas

Summary A study of the ignition of pyroxylin, polyvinyl nitrate, barium azide, and nitrostarch in a hot gas in the temperature range 200–600° C with induction periods of 0.1–100 sec has shown that the laws of the process are determined by exothermic reactions in the condensed phase and may be quantitatively described on the basis of the modern thermal theory. The theoretical relations can be used to determine the effective kinetic parameters of the high-temperature high-speed reactions of thermal decomposition of condensed substances from ignition experiments.Fizika Goreniya i Vzryva, Vol. 3, No. 4, pp. 512–526, 1967