Experimental study of the effects of vent area and ignition position on internal and external pressure characteristics of venting explosion

Explosion venting can cause not only internal damage but can cause external damage to buildings. Since little attention is paid to the damage caused by both explosions simultaneously, vented explosion tests were performed in a 4.5 m(3) square chamber, to investigate the internal and external pressure characteristics and their correlation. The results show that ignition location has little effect on venting pressure (P-1), but significantly affects the Helmholtz oscillations and high-frequency oscillation pressure (P-4). Central and front ignitions lead to the maximum P-4 and longest Helmholtz oscillation, respectively; during venting, two pressure peaks (defined as P-e1 and P-e2) were recorded due to the shock wave and combustion wave, respectively. P-e1 has an inverse proportional relationship with distance. P-e2 is proportional to P-1. When the vent area exceeds 0.16 m(2), P-e2 under rear ignition plays a more dominant role than that of other ignition points, however, the vent area is equal to 0.16 m(2), P-e2 with central ignition becomes dominant. The external pressure peaks corresponding to the external flame development were captured. The longest length of the jet flame was observed at central ignition and rear ignition forms the largest external combustion area.