Research On Migration And Dynamic Characteristics Of Two-phase Flow Of Coal And Gas Outburst In Roadway

Coal and gas outburst is an extremely complex gas dynamic disaster in coal mines.Many experts and scholars have made many useful explorations on the mechanism of its occurrence and the pressure disturbance and damage to the roadway after the outburst occurs.In order to further study the movement and dynamic characteristics of the pulverized coal-gas two-phase flow after outburst,this paper uses aerodynamics and two-phase fluid dynamics as the theoretical basis to build a coal and gas outburst test system in the laboratory for experimental research.The Fluent numerical simulation software is used to analyze the migration law of prominent two-phase flow in different types of roadways.The main research conclusions of this paper are as follows:1)When the two-phase flow spreads in a straight roadway,the strength of pulverized coal blow and the strength of impinging air flow decrease with the increase of the distance of the two-phase flow.The characteristics of the accumulation of pulverized coal in a straight roadway after the outburst is that there is less pulverized coal in the front and back sections of the roadway,while a large amount of pulverized coal is distributed in the middle section.The quality of pulverized coal accumulation in the entire roadway is normally distributed.Using the high-speed imaging system to observe and calculate,the speed of the pulverized coal flow when passing through the three measuring points are 25m/s,21.74m/s and 13.89m/s.The speed of the pulverized coal flow increases with the increase of the distance of pulverized coal transportation.attenuation.2)When the prominent two-phase flow propagates in the bifurcated roadway,the test results show that the attenuation coefficient of the impinging airflow in the branch roadway is about 5.76 times that of the main roadway.Through the comparative test of 90° bifurcation roadway and 45° bifurcation roadway,it can be obtained that the attenuation coefficient of impinging airflow in the main roadway increases with the increase of the bifurcation angle,while the attenuation of the impinging airflow in the branch roadway The coefficient decreases with the increase of the bifurcation angle,which indicates that the greater the bifurcation angle of the bifurcation roadway,the higher the energy of the impinging airflow entering the branch roadway,while the energy of the impinging airflow entering the main roadway will decrease accordingly..The quality distribution of pulverized coal in the bifurcated roadway after the outburst is calculated.The distribution law of pulverized coal in the main roadway is similar to that in the straight roadway,but compared with the main roadway,the quality of pulverized coal distributed in the branch roadway is much smaller than that in the main roadway.In the outburst test of the four-component fork roadway,the quality of pulverized coal in the branch roadway accounted for 0.36%,0.54%,0.59%,and 1.56%of the total pulverized coal mass respectively.Through the migration test of the prominent two-phase flow in the turning roadway,it is concluded that the intensity of the prominent impinging airflow pressure is greatly reduced after passing through the corner.Due to the obstructive effect of the wall,a large amount of protruding coal powder is deposited at the corner and further obstructs the migration of the rear two-phase flow.3)The Fluent software was used to numerically simulate the migration of outburst coal with three different outburst diameters of 40mm,80mm and 200mm.The results show that the average speed of outburst coal powder is positively correlated with the outburst diameter.The numerical simulation results of the outburst two-phase flow propagation in the 60°,90° and 120° bend roadways show that the pulverized coal velocity and the attenuation coefficient of the impinging air flow pressure decrease with the increase of the turning angle.Numerical simulation results of the propagation law of outburst two-phase flow in 30°,60°and 90° bifurcated roadways show that the larger the bifurcation angle,the lower the transportation speed of pulverized coal in the branch roadway and the impact air pressure in the branch roadway.The faster the decay.The law in the main lane is the opposite.The greater the bifurcation angle,the slower the attenuation of the impact air flow after passing through the bifurcation.The numerical simulation results are consistent with the experimental research rules.Figure[54]table[3]reference[62]...