Study On The Propagation Law Of Gas Explosion In The Space With Characteristics Of Goaf

Gas explosions causing heavy casualties in the goaf of coal mine sometimes occurred.,which will seriously threaten the life safety of underground workers.The spatial structure in the goaf is very complex and is a feature of the combination of gaps and voids.Under the action of mine pressure,the falling rocks and coal gangue in the “self-ignition zone” will have smaller gaps;the “cooling fins” will have a large gap due to the free accumulation of falling rocks.The goaf in coal mine is a multi-scale complex medium with pores in remaining coal,the gap among rock blocks and holes which don't meet these characteristics of porous medium.The propagation of gas explosion flames and shock waves in the goaf is very complicated.Based on the spatial structure characteristics of the goaf,the numerical model of gas explosion and the physical model of 30m×0.5m×0.5m square tube are established by using the OpenFOAM open source CFD source code.Gas explosion flame and shock wave propagation characteristics are analyzed under the conditions of coordinating and derangement arrangement for the same diameter rock or diameter gradient rock block.The results reveal that the flame propagation speed in the square tube of the spatial characteristics of the goaf is significantly higher than that of the smooth closed air tube.When the Volume ratio of solid sphere to hollow cuboid(K)changes,the flame propagation speed,shock wave strength and pressure rising speed also change accordingly.The flame propagation speed of gas explosion in the model of coordinating and derangement arrangement differs by less than 100 meters per second.At the same concentration,the rate of temperature rise in the model of coordinating is larger.but the rate of pressure rise in the model of th e rock derangement arrangement is twice larger than the pressure rise rate of the coordinating arrangement.In the model of different rock mass diameters,the flame propagation speed of coordinating and derangement arrangement are both increased first and then decreased.The flame propagation speed,shock wave strength and pressure in the coordinating arrangement model are higher than the derangement arrangement.The research results will be of great guiding significance for the prevention and control of gas explosions in the goaf,the investigation and analysis of gas explosion accidents.There are 47 figures,10 tables and 60 references in this dissertation.