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

Abstract

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.

Cluster evolution during the early stages of heating explosives and its relationship to sensitivity: a comparative study of TATB, β-HMX and PETN by molecular reactive force field simulations

“…Clusters have been shown experimentally and theoretically to be the intermediates and/or final products of the deflagration and detonation of some explosives. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Experimental observations show that clusters are mainly composed of carbon with a small content of nitrogen, oxygen and hydrogen. These clusters include various carbon polymorphs such as diamond, graphite, nanotubes and other amorphous forms of carbon.…”

“…These clusters include various carbon polymorphs such as diamond, graphite, nanotubes and other amorphous forms of carbon. [2][3][4][5][6][7][8][9][10][11] Interestingly, some clusters were thought to be useful nanomaterials, and thus deflagration and detonation were regarded as feasible approaches for creating these materials. For instance, Greiner et al 4 and Xu et al 5 prepared diamonds by detonating C-rich explosives.…”

On the mechanism of carbon nanostructures formation at reaction of organic compounds at high pressure and temperature

“…Foam-like structures were obtained in inert atmosphere at low pressure. 45,46 In the work, 47 formation of nets with a dimension 2.2 was observed, the formation of carbon clusters at combustion and detonation of gas mixtures was investigated, and clusters of different modifications we obtained, from fullerene-like to long branched carbon structures.…”

Melting Point of Carbon Particles behind the Gas Detonation Front

“…Достаточно полный обзор публикаций по данному направлению представлен в [1]. В последнее время значительное внимание стало уделяться детонационному (взрывному) сжиганию смесей на основе ацетилена или других газообразных топлив при дефиците окислителя (кислорода или воздуха), поскольку при таком способе сжигания углеводородов в продуктах детонации возможно формирование наноразмерного углеродного конденсата с особыми свойствами [2][3][4]. Новые возможности для его производства открывает импульсный газодетонационный аппарат (ИГДА), который был разработан на базе компьютеризованного комплекса CCDS200 для нанесения порошковых покрытий (детонационного напыления) [5; 6].…”

“…При изучении физико-химических свойств ДНУМ полезна информация об условиях (давлении и температуре), при которых он формируется за фронтом детонационной волны. С этой целью в [2] предпринята попытка оценить параметры самоподдерживающейся детонации, когда молярная доля (концентрация) ацетилена в смеси больше, чем у кислорода, и в продуктах химической реакции возможно появление свободного углерода. Расчеты выполнены для двух предельных случаев: когда углерод находится в продуктах детонации 1) только в газообразном состоянии, 2) только в конденсированном состоянии.…”