Research On The Mechanism Of The Damage Of Reverse Air Door By Outburst Coal And Gas Two-phase Flo

In recent years,coal and gas outburst accidents have occurred frequently in China’s coal industry during the mining process,which has extremely affected the safety production work of coal.When the outburst accident occurs,once the reverse dampers are damaged and fail,they cannot stop the reverse flow of gas and the ejected pulverized coal flow,which brings great threat to the safety of personnel and equipment.Therefore,it is necessary to study and analyze the force state of the reverse dampers after being impacted by the pulverized coal-gas flow,find the weak parts of the reverse dampers,and combine the relevant factors affecting the strength of the reverse dampers to carry out safety design and strength optimization of the reverse dampers,so as to improve the disaster resistance of the reverse dampers.This paper combines theoretical analysis,experimental research and numerical simulation to analyze the force situation and deformation of the reverse dampers caused by the shock wave formed by the two-phase flow of coal and gas.The main research results are as follows.(1)The initial energy source of the protruding coal and gas two-phase flow is analyzed,the one-dimensional constant model of the coal dust-gas two-phase fluid after outburst is established,and the process of coal and gas two-phase flow shock wave formation and propagation is elaborated.In the process of shock wave propagation,the change of motion state of coal dust is related to the force it is subjected to.Based on the three criteria of shock wave damage effect,it is known that the damage effect of shock wave on the object is mainly influenced by the overpressure and impulse acting on the object.Combined with the parameters of the damage effect of shock wave on reverse dampers to calculate the damage effect of shock wave on reverse dampers,it shows that the damage state caused by shock wave on reverse dampers from outburst is not only related to the action of shock wave,but also influenced by the shape,own strength,material and other factors of reverse dampers.(2)Based on the coal and gas outburst test device,the coal and gas outburst test was carried out under two kinds of outburst pressure of 1 MPa and 0.74 MPa,and two kinds of reverse dampers made of steel and wooden structure.The test results show that after the occurrence of outburst,the state of coal dust accumulation in the roadway mostly presents the state of stratified flow and bolted flow.The gas expansion energy and outburst strength inside the coal increased with the increase of gas pressure,and the small particle size coal dust was mostly distributed in the back of the roadway,and the large particle size coal dust was mostly distributed in the front of the roadway.Under the same outburst pressure,the lower position of the reverse dampers is subjected to the greatest force,and the bottom of the dampers is most easily damaged;the micro-strain produced by the reverse dampers of steel structure is smaller than that of wooden structure dampers,and the load resistance of the reverse dampers of steel structure is better than that of wooden structure reverse dampers.(3)The finite element software ANSYS Workbench was used to simulate the stress state of the reverse dampers structure under the action of the shock wave of the two-phase flow of coal and gas under different outburst pressure.The simulation results show that when the four sides of the reverse dampers are fixed,the maximum stresses generated by the dampers are mainly concentrated in the middle part of the four sides of the dampers and the center of the dampers.The area where the maximum deformation of the dampers occurs is distributed in the central position of the dampers,and the closer to the middle of the dampers,the greater the deformation occurs,and the more the dampers will be deformed as the impact load increases.At the same time,the deformation of wooden structure dampers occur more than steel structure dampers.(4)Combined with the information about the "2-13" large coal and gas outburst accident in Hongyuan coal mine,the overpressure value of the shock wave propagating to the reverse dampers and the maximum stress value acting on the reverse dampers were calculated theoretically,and the dampers were judged to be damaged,which is consistent with the case site.Based on the impact force resistance and strength analysis of the reverse dampers structure,the reverse dampers structure is optimized to improve the strength of the reverse dampers structure and measures to enhance the safety performance of the reverse dampers are proposed.Through tests and simulations,we analyze the damage effect of the shock wave generated by the two-phase flow of coal and gas on the reverse dampers,determine the easy damage characteristic points of the dampers structure,explore the factors affecting the strength of the reverse dampers structure,provide technical references for the strength design and location arrangement of the reverse dampers structure,and achieve the purpose of improving the disaster resistance of the reverse dampers.