Propagation of gas explosions of different volumes in a large test tunnel

Abstract

ABSTRACT With the continuous development of coal science and technology, gas explosion disasters have become an important factor in restricting efficient and intensive coal mining which threaten safe production in coal mines. In a large test tunnel, gas explosion propagation tests were conducted by taking gas-air mixtures with different volumes of 50 m3, 100 m3, and 200 m3 as explosion sources. The results demonstrate that, at a given gas concentration, the larger the volume of the gas-air mixture, the stronger the explosive power and the further the flame propagates. The pressure near the explosion source does not necessarily the maximum value in the whole gas explosion process. In the increasing propagation distance, explosion pressure does not linearly attenuate but fluctuates along the tunnel. The flame propagation velocity increases and then decreases throughout the explosion in three stages: a slow propagation stage at the beginning of an explosion, an accelerated propagation stage, and a decelerated propagation stage before flame extinction. Shock waves generated by a gas explosion interact and influence explosion flames and there is a positive feedback mechanism that promotes their mutual interaction. The conclusions provide an important theoretical basis for preventing gas explosion accidents and formulating active measures for explosion suppression in underground coal mines.