Numerical Simulation Of Gas Deflagration Characteristics In A Closed Straight Pipe

Coal is the main energy source in China.In the process of coal mining,gas explosion accidents occur frequently,which bring huge losses to the national economy.When an explosion occurs,if not ventilated in time,the explosion zone can easily be triggered by a secondary explosion.The first explosion can cause high temperature and pressure in the tunnel,the shockwave can cause the culvert to collapse,causing the traffic jam of all kinds of production equipment.Overall,the current research on gas explosion propagation process is not comprehensive enough,less research has been done on the impact of the explosion on fuel temperature and environmental pressure,study on the impact of obstacles on explosion propagation is not enough,there are few researches on the influence of multi factor coupling on the propagation of explosion.In this paper,a two-dimensional rectangular model is established.Firstly,based on experimental data in a literature,using FLUENT software to simulate the detonation propagation inside the closed straight pipe,by comparing the simulated data and experimental data,verify the calculation model and parameters of rationality and accuracy.Secondly,based on the grid independence verification,the effects of the fuel temperature and environmental pressure on the detonation propagation are studied,and the effects of the blockage rate,the location of the obstacle and the length of the obstacle on the deflagration propagation are studied.Finally,two sets of orthogonal experiments are designed to study the effect of multi factor coupling on the detonation propagation process.The results show that the increase of fuel temperature and environmental pressure will significantly accelerate the process of deflagration,the peak pressure reduce with the increase of temperature,the peak pressure increases with the increase of environmental pressure.As the obstruction of the pipe increases,the flame accelerates more effectively,obstacles set in laminar burning zone will change the flame on the surface of the array development,deepen the imbalance of flame shape.When the obstacle is set in a turbulent combustion area,the closer the source of the ignition,the better the acceleration of the flame.Obstacles appropriately extended,will further increase the flame front turbulence kinetic energy,when the obstacle is too long,the turbulent kinetic energy will decrease,thus weakening the flameacceleration effect.Orthogonal test showed that,under the coupling conditions of fuel temperature,environmental pressure and blocking rate,the influence of fuel temperature on flame acceleration is greater than that of environmental pressure,and the blocking rate is the least in the three factors.Under the coupling condition of the blocking rate,the obstacle position and the obstacle length,the influence of the position of the obstacle on the acceleration of the flame is greater than the length of the obstacle,and the blocking rate is the smallest in the three factors.