The effect of pipeline structure on the flammability characteristics of hydrogen-air premixed gas under end-opening conditions

Abstract

The pipe structures and opening conditions have an important influence on gas explosion, but little research has been done on the coupling analysis of the two. In order to reveal the effect of pipe structure on the flammability characteristics of hydrogen-air premixed gas under end-opening conditions, the flame structure, flame propagation velocity, explosion pressure and flow field distribution in the explosion process of hydrogen-air premixed gas in different pipe structures were analyzed by numerical simulation. The results show that the flame propagation velocity and pressure are less influenced by the end-opening structure in the initial ignition stage, however, when the flame propagates to the pipe end, the flame propagation velocity in each pipe structure is significantly enhanced. The 90? elbow has a certain inhibitory effect on the flame development, while the T-shaped bifurcation structure can effectively increase the degree of gas detonation. In pipe with large aspect ratio, due to the wall effect, the effect of acoustic oscillation disturbance on the flame front and the airflow release effect of the end-opening, there are two peaks and two troughs in the pressure rise rate curve of each pipeline structure.