Pressure characteristics during vented explosion of ethylene-air mixtures in a square vessel

The vented explosion in a 2 m × 1.1 m × 0.5 m stainless cylindrical vessel with the ethylene-air mixture is investigated as the function of the ethylene concentration, vent area and vent burst pressure. The internal pressure histories measured by two piezoelectric transducers with the vented door of different thickness are used to analyze the effect of vent burst pressure on the whole explosion. It is shown that the peak overpressures are the highest just at the ethylene concentration is 8 vol%. The internal overpressure is grown with the concentration and in turn decreases after internal pressure reached the peak. As the vent burst pressure increases, the same trend that internal peak overpressure is increasing accordingly is found. The dominant peak overpressure will be change with different vent areas. Not only that, it is apparent that venting is more effective on the account of the low ethylene concentrations. The high-speed images demonstrate that the flame is strongly distorted and the unburned mixture is ignited by the external flame. The comparison between experimental results and calculation values has been discussed in consideration of the influences of vent area and vent burst pressure. The predicted overpressures of different theoretical models are relatively conservative than measured peak overpressures.