Experimental and simulation study on overpressure and flame propagation dynamics of full-scale liquefied petroleum gas explosions

To explore the hazard characteristics of liquefied petroleum gas (LPG) explosion in complex residential environment, a full-scale gas explosion experimental platform and numerical model were established in this paper. The spatial and temporal evolution law of explosion overpressure multi-peak structure and the distribution characteristics of peak overpressure under different ignition positions were studied, and the flame competition propagation mechanism induced by spatial layout and explosion-venting was revealed. The results show that the typical overpressure curve is composed of five peaks ( P_b-g , P_b-d , P_cv , P_ext , P_hel ), and gradually evolves into four-peak, three-peak and double-peak with the increase of distance from the vent. The maximum overpressure near the vent and the indoor depth zone is dominated by the peak P_ext and P_cv , respectively. The personnel death zone (overpressure greater than 100 kPa) is mainly distributed in the far field opposite to the ignition and near the roof. The area of the death zone increases in a cubic function with the height of the section, and the largest proportion of the cross-sectional area of the whole room is 40 %. The failure of doors and windows induces the formation of ’anti-tulip’ flame structure. The flame propagation in the foyer and the entryway is affected by the coupling effect of the split-flow suppression and the split-flow acceleration, and the velocity shows a competitive propagation behavior that first decreases and then increases. The research conclusions provide experimental and theoretical reference for improving residential gas explosion prevention and control. Practically, the findings guide post-accident investigation, blast-resistant design, and venting strategies.