Study On Propagation Characteristics Of Gas Explosion Under Condition Of Additional Cavity

Coal is main energy in our country,but gas explosion occurs occasionally during the process of coal mining,and it causes heavy casualties and property losses after the shock wave acting on the coal mine roadway,supporting,equipment and downhole workers.So the gas explosion seriously influences the coal mining safety and restricts the development of production safety in our country.As the current researches mainly focus on the gas explosion possibility control,the gas explosion consequences severity research is relatively weak.Correspondingly,the mitigaiton technical measures are also less,taking the death of more than 100 people since the founding of the PRC in coal mine as an example,the number of deaths caused by gas explosion accounts for 82.1%.Therefore,it is necessary to carry out new research to reduce the the damage and casualty of gas explosion.It is of great significance to the work of disaster mitigation in coal mine.Based on previous studies,the mechanism of the internal chain reaction and propagation of gas explosion was expounded.Also based on the process of deflagration to detonation of gas explosion propagation in the pipe network,the parameter equations of deflagration to detonation were deduced and the simplified equations were also got.Besides,the incident wave and reflected wave velocity evolution equation and the gas pressure evolution equation of gas explosion propagation were deduced when the gas explosion encountered the rigid surface.The damage and damage mechanism of gas explosion was expounded based on the overpressure-impulse criterion.By the method of numerical simulation of the influence of single cavity(such as 300*300*200 and 500*500*200)to the gas explosionon,it is found that for the 300*300*200 cavity,the peak overpressure of the point as100 mm after export was 1.41 times to the entrance.That is,the gas explosion shock wave had been promoted because of the 300*300*200 cavity.For the 500*500*200 cavity,the peak overpressure of the point as100 mm after export was 83 percent of the entrance,which showed the effect of wave absorbing.A large pipe gas explosion system was set up which length is 36 meters and diameter is 200 milimeters.And the system mainly includes explosion test network subsystem,gas distribution subsystem,ignition subsystem,data acquisition subsystem and high-speed video subsystem.In combination with the results of numerical simulation,eight different single cavities were made such as 300*300*200,300*500*200,300*800*200,500*300*200,500*500*200,500*800*200,800*300a*200 and 800*500*200.And then the wave absorbing and its effect tests of the single cavity were carried out.The results showed that 500*800*200 cavity had the best effect,with its attenuation rate of flame front being 38.0%?87.0%,and the attenuation rate of shock wave overpressure being 37.71%?37.71%.On this basis,further study of two cavity composite structure(such as 55-35,58-33,58-35,58-38,85-35,35-58)were carried out,and the results showed that the 58-35 cavity composite structure was the best composite structures,as the attenuation rate of flame front was over 90%,and the attenuation rate of shock wave overpressure was over 70%under most conditions.Then a further study of 58-35-55 cavity composite structure was carried out for promoting wave absorbing,and the results showed that the attenuation rate of flame front was 92%?99%,and the attenuation rate of shock wave overpressure was 46%?46%,which was similar to the results of 58-35 cavity composite structure.In view of the feasibility and safety of the application in coal mine,the 58-35 cavity composite structure was considered to be the best combination cavity for wave absorbing.Based on this,combined with the "11.28" gas explosion in chenjiashan coal mine,a numerical simulation of the 58-35 cavity composite structure was carried out,and the results showed that it reduced mortality by about 30%.By the theoretical analysis,numerical simulation and experimental research,the wave absorbing feasibility and beneficial effects of cavity were studied in coal mine.The research results provide new ideas and new ways to reduce the gas explosion consequences severity.And so the paper has great scientific value and practical significance for the prevention of gas explosion disaster in coal mine.