Numerical Analysis Of Aluminum-air Mixture Reaction For Thermo-baric Explosive

From the theoretical point, this paper conducted a preliminary study on the four destructive elements of thermo-baric explosive blast field, and got a simple analysis of the destruction about fragments and overpressure. It also summarized the fireball thermal radiation and the lack of oxygen to the targets which were difficult to get by experiments, it was very important to study the properties on damage. To get the temperature and species concentration which were difficult to measure by experiments, and to further inform the fireball thermal radiation power and the scope of hypoxia, this paper proposed an after-burning model of aluminum powder for thermo-baric explosive by analyzing the detonation mechanism of aluminized explosives. Using the LS-DYNA software, a numerical simulation was finished based on a point explosion model for a fixed charge amount of TNT explosive in semi-open space, to reproduce the process of TNT detonated, the formation and propagation of air shock wave, shock wave interactions and reflection on the ground, which obtained the pressure distribution laws after the first blast wave effects on the flow field. The results to p-t curves of the monitored units which at a distance of 0.5m from the explosion center were synthesized to sub-function based on the least square method by using MATLAB software, and entered into UDF of the pressure inlet boundary condition to the FLUENT software. Taking into account the after-burning effect of aluminum powder, the k-εstandard turbulence model, discrete phase particle surface combustion model, EBU model and thermal radiation P-1 model for FLUENT, the process of 2kg aluminum powder dispersion and rapid combustion was simulated. Calculation shows that, the ratio of after-burning pressure to shock wave pressure is about 40% at least, and the positive effect time is increased about 8ms～25ms. It indicates that aluminum powder has a dominated advantage for improving the working capability to explosive. Through the comprehensive analysis, it studied the effects on the blast flow field caused by after-burning reaction of aluminum powder, also the overpressure field, velocity field, temperature distribution, thermal radiation damage powers, particle concentration and each component changed, etc.In his paper, the problem of dispersion and rapid combustion to aluminum powder for thermo-baric explosive was simulated effectively by FLUENT. It also solved the shortcomings when simulating the temperature, components transportation, chemical reactions through using LS-DYNA software, and the explosion by FLUENT. It also got the temperature and species concentration from the flow field which were difficult to measure by experiments, and further obtained the fireball thermal radiation power and the scope of hypoxia. It provides a reference for the study on different killing characteristics of the thermo-baric explosive blast field, which is of great significance.