Experimental study on hydrogen-air premixed gas explosion in confined space

Abstract

ABSTRACT In order to explore the explosion characteristics of hydrogen-air premixed mixtures and to characterize the damaging effect of the explosion shock wave on the surrounding structures, a closed straight detonation pipeline is designed and applied to simulate a confined space in this study. The inner diameter of the designed pipeline is 6.4 m long and 125 mm wide. The results show that the maximum flame speed of the most combustible premixed gases usually occurs near the equivalent ratio of 1 (hydrogen volume concentration is 29.6%). However, because of the influence of Graham’s law in chemical reaction kinetics, the maximum flame speed of hydrogen/air premixed gas appears near the equivalent ratio of 1.5 (hydrogen volume concentration is 39.6%). At this concentration, the maximum flame propagation speed reaches 1810 m/s and the pressure peak reaches 1.53 MPa. The elbow structure has a significant effect on the explosion flame. The explosion pressure and flame propagation velocity drop sharply when the premixed gas enters the bend. The explosion pressure is reduced by 11.3% and the flame propagation velocity is reduced by 66.59%. However, the velocity of flame propagation increases by a maximum of 34.41%, and the explosion pressure increases by a maximum of 26.1% when the premixed gas passes the turning point of the elbow. The thin-wall strain response of the pipeline is in good agreement with the explosion pressure.