With the progress of science and technology,China ’s coal mines have become large-scale mining.At present,there are many mines with mining capacity of tens of millions of tons,and the distribution of underground roadways and equipment in coal mines is more complicated.At the same time,the occurrence conditions of coal mines in China are complex.Most of the mines are gas mines,and some are coal and gas outburst mines.When gas is mixed with air,it will explode when it encounters an open fire when it reaches a certain concentration.The conditions in the underground roadway are complex,and different shapes and quantities of mining equipment as obstacles have incentive effects on gas explosion.At the same time,the participation of coal dust increases the power of gas explosion and increases the harm of gas explosion.Studying the influence of different shapes and numbers of obstacles on gas explosion under the participation of coal dust is helpful to correctly understand the destructive effect of gas explosion and the incentive effect of obstacles on explosion,provide theoretical support for disaster prevention and mitigation,and provide guidance for the design of underground equipment layout and facilities,so as to weaken the destructive effect of gas explosion and improve the efficiency of coal mine safety production.Therefore,this thesis studies the propagation of 9.5% concentration gas explosion in long straight pipeline and 9.5% concentration gas explosion with 5g/m3 coal dust.The structure of explosion flow field,explosion overpressure and flame propagation velocity were investigated when circular,triangular and rectangular obstacles or 1-3rectangular obstacles were added,or 3 obstacles of different shapes were added simultaneously.In this thesis,numerical simulation analysis is adopted,and theoretical analysis and experimental verification are combined.Fluent software was used for numerical simulation,and Euler-Lagrange model was used to simulate dust and gas explosion.The mesoscale shock pipe and laser schlieren system,combined with pressure and photoelectric sensors,were used to analyze the flow field structure,flame propagation velocity and pressure changes of the dust and gas explosion.The simulation results are consistent with the experimental results,and the main conclusions are as follows:1)The flow field structure is more complex in the case of dust and gas explosion,and the promotion effect of coal dust and obstacles on the flame propagation speed of gas explosion will appear mutual inhibition,but the maximum overpressure is higher than that in the case of single factor.2)When the obstacle is involved,the maximum overpressure near and downstream of the obstacle will be increased,but the change law of the maximum overpressure of the closed pipe will not be changed with the increase of distance;The flame goes through four stages of "acceleration-deceleration-re-acceleration-redeceleration".3)For obstacles with different shapes,rectangular obstacles have the most obvious excitation effect on dust and gas explosion,followed by triangular obstacles and circular obstacles.With the increase of the number of obstacles,the explosion excitation effect on dust-containing gas gradually increases.When the number of obstacles increases to 3,the flame propagation speed and explosion overpressure reach the maximum.4)When obstacles of different shapes exist at the same time,the influence of rectangular and triangular obstacles on the flow field structure is dominant,and the flame propagation speed and maximum explosion overpressure are slightly lower than that of the three rectangular obstacles.5)In order to reduce the harm of gas explosion accidents,obstacles conducive to flow instability,such as rectangles,and continuous placement of obstacles should be avoided in mine roadway as far as possible... |