| The greatest disaster in coal mine is gas explosion. Recently more and more gas explosions occur in coal mine. The explosions have made a great loss. There are lots of obstructions such as apparatus and machines etc. almost in all explosions locales. The obstructions make explosion more powerful and loss greater. However, the obstacles always are stereo. It is necessary to study the effects of the stereo obstacles on the gas explosion in coal mine.The pipeline gas-dust explosion testing device used is designed by our security technology center, and by which the effects of different spatial structure of obstacle on flame propagation speed and overpressure is studied. Three solid structure obstacles are cube, triple prisms and cylinders. Each is adopted with three kinds of blockage ratios: 20%, 40% and 60%.The main work and conclusions are as follows:(1)The stereo obstacles have an important affection to the gas flame propagation speed and overpressure even if which have small recent. The obstructions accelerate remarkably the explosion of methane air and mixed gas comparing with no obstruction.(2)The enhancement of blocking ratio of obstacles and the augment of the number of obstructs result in the rapid increase of flame velocity and the strengthen of overpressure in closed vessels. The positive feedback mechanism of mutual acceleration among obstacle, turbulent flow and flame is explained. When the amount of obstructions is 2, the pressure and flame velocity both reach the maximum respectively. However, the addition of numbers of obstacles will cause the reduce of flame velocity and explosion pressure. The results show that there is a acceleration limit of obstacles.(3)Under the same blocking ratio condition, the cube has the most ability to accelerate, while cylinder have the least influence, the effect degree of triple prism is middling.The results are expected to have some help on preventing and controlling methane explosive in mine and providing reference for industry safety design.
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