| Aluminum is a lively industrial raw material.It will produce dust during use,storage and transportation,and it may explode when it encounters an ignition source with sufficient energy.A large number of explosion accidents are secondary explosions of dust caused by the explosion of electrical appliances or combustible gases.The secondary explosion of aluminum powder or the explosion of multiple explosives is far more violent than a single gas phase explosion.This paper adopts the method of experimental research and simulation calculation to explore the law of pressure propagation when a two-phase explosion occurs when methane ignited aluminum powder.The experimental research is divided into three parts:a comparative experiment with premixed methane gas as an explosive and a comparative experiment with methane and aluminum powder(6 μm,400 g/m3)as an explosive.The analysis shows that the addition of aluminum dust in the explosive will appear after multiple explosions,the shock wave intensity after the explosion will be greatly enhanced;change the total amount of aluminum powder to create dust clouds with concentrations of 200 g/m3、300 g/m3、400 g/m3、500 g/m3、and 600 g/m3.The explosion results show that keep the particle size unchanged,the maximum explosion pressure will first rise and then decrease with the increase of the concentration;keeq the total amount of aluminum powder unchanged,change the particle size of the filled aluminum powder from 6 μm,12 μm,18 pun,24 μm,30 μm in sequence As the particle size decreases,the maximum explosion pressure appears to increase first and then decrease.The simulation research based on the simulation software ANSYS FLUENT is divided into two parts:the comparison and analysis of the results of numerical calculation and experimental research of aluminum powder explosion in horizontal straight pipes,it is found that the two have a higher consistency,and the intensity of the explosion impact increases first after decreasing,the shock wave’s destructiveness reaches the maximum at the end of the combustion zone.Formulate a feasible simulation plan to calculate the propagation characteristics of the pressure wave when the aluminum powder explosion occurs in a pipe with a bend structure and a"T" bifurcation structure.The simulation results show that when the shock wave passes through the turning structure and the bifurcation structure,low-pressure vortices and high-pressure regions of different sizes are formed.The turning structure mainly reflects the shock wave,and the bifurcated structure mainly plays the role of shunting the shock wave.Compared with straight pipes,the pressure decays faster than straight pipes when no combustibles are filled in the two structures.The research results in this article have a guiding role in production activities,and industrial environments where multi-phase combustibles coexist should be prevented and chain explosions should be prevented.The process involving metal dust should also avoid the generation of dust particles with too small particle size,and pay attention to taking dust reduction measures to prevent the formation of dust clouds.The research results also show that both the turning structure and the bifurcation structure can play the role of attenuating the shock wave,and have enlightenment in reducing the consequences of explosion accidents.However,dust particles are more likely to accumulate at comers and bifurcation structures.When using a dust removal system or transportation system with a bend or bifurcation pipe,it is necessary to clean up the dust in time.Figure 39 table 9 reference 83... |
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