Research On Propagation Characteristics Of Coal Dust Explosion In Diagonal Pipe Network

In this paper,experimental study,numerical simulation and theoretical analysis are used to study the propagation and attenuation process of flame temperature,pressure and impinging air flow in the pipe network after coal dust explosion in the diagonal branch.The variation of parameters after secondary explosion of coal dust deposited in pipe network and its influence on primary explosion are studied,The research results provide theoretical support for the risk analysis and Rescue Decision of coal dust explosion accident.In the experiment,the maximum pressure and pressure rise rate of four kinds of coal dust cloud explosion were studied in 20 L ball.It was concluded that under the same test conditions,the explosion pressure and pressure rise rate of lignite were the largest.The propagation characteristics of explosion flame were tested in a straight pipe,which provided theoretical and parameter basis for numerical simulation;the physical model of 1:1 of the pipeline of intelligent coal dust explosion identification device was established by FLACS software,the numerical simulation of coal dust explosion was carried out based on the experimental parameters,the simulation results showed that the flame length of coal dust explosion was compared with the experiment,and the feasibility and accuracy of simulating coal dust explosion with FLACS were verified.FLACS software is used to establish the physical model of the diagonal pipe network,the propagation characteristics of shock wave,high temperature flame and impinging air flow in the pipe network after coal dust explosion in the diagonal branch are simulated and analyzed,the explosion propagation process is analyzed from the time-space relationship of the three.The pressure attenuation law of shock wave passing through the bifurcation of pipe network is analyzed.It is concluded that the greater the bifurcation angle is,the greater the pressure attenuation amplitude is.Under the same bifurcation angle,the greater the initial pressure is,the greater the attenuation amplitude is.The relationship between wave front velocity and shock wave overpressure and the acceleration effect of turbulence on explosion are analyzed.Based on the simulation data,the shock wave attenuation formula in the bifurcated pipe is used,and the overpressure values of shock wave after different bifurcation angles are calculated by using the mathematical solution program.The relative error between the theoretical solution and the numerical simulation results is small,which indicates that the theoretical formula and the numerical simulation are mutually verified.The relationship between the attenuation coefficient of shock wave pressure and the initial pressure and different turning angles is obtained by multiple regression fitting of the pressure simulation values before and after turning.The fitting results can be used as the formula for the ventilation network solution in the later catastrophic process.As for the second explosion,the whole process of deposited coal dust rising caused by the high-speed airflow in front of shock wave at different times after the first explosion was simulated and analyzed,The variation law of shock wave pressure,flame and air velocity at each monitoring point before and after the secondary explosion were analyzed,Comparing the characteristics of coal dust secondary explosion and primary explosion,it is found that the maximum pressure and pressure rising rate of coal dust secondary explosion are larger,the flame propagation speed is faster,and the air flow speed is larger,which shows that the destructive effect of secondary explosion is stronger.This paper has 60 pictures,40 tables and 120 references.