Effects of ignition position and surface density of hinged panel on vented hydrogen-air deflagrations

This study investigates surface density ( W s ) effects on flame and pressure dynamics of hydrogen-air mixtures, under initial conditions of 290 K and 100 kPa, in a 1 m 3 chamber under bottom (BI), central (CI), and top (TI) ignition. Results show four pressure peaks ( P 1 – P 4 ) emerge, with P 1 reflecting the venting-combustion balance. Specifically, TI is dominated by internal acoustic standing waves at the bottom, while BI is driven by external feedback shock waves near the vent. Observations indicate that while P 1 increases monotonically with W s under TI, it exhibits a non-monotonic trend under BI, reaching its peak at W s = 13.5 kg/m 2 before declining. Internal maximum pressure ( P max ) peaks non-monotonically at 8.1 kg/m 2 (TI/CI) and 10.8 kg/m 2 (BI). The external overpressure was highly sensitive to the ignition position. Specifically, an inertial vent panel amplifies P ext under CI, whereas it reduces P ext under BI.