Earth-covered magazine has some characteristics that are safer than the above-ground magazine and are more economical than underground magazine. To investigate the pressure distribution and the structural failure under the internal explosion, the scaled tests of the earth-covered magazine were conducted under a 0.5 kg TNT explosive charge. The overpressure in the 0°, 90°, and 180° directions outside the structure and the debris distribution were obtained. The numerical simulations were constructed in LS-DYNA software to analyze the test results. The results show that the external overpressure has a directional characteristic that the maximum and minimum overpressure appear in 0° and 180° directions, respectively. In the double logarithmic coordinate system, the overpressure peaks in three directions are linearly related to the scaled distance. Most of the fragments in the 0° direction hit the ground within the front range of ±60°, and the further fragments (40 m or more) were confined to a limited sector within the front range of ±30°. The internal explosion numerical simulation shows that the concrete cracks first appeared at the roof and the ground, and then the damage occurred at the intersection of the walls, and then the damage occurred at each surface. The maximum debris velocity of the side and rear walls is lower than that of the front wall due to the limitation of the soil. The motion equations of the debris combined with numerical simulation can be adopted to predict the projection distance of fragments.
A simplified model that calculates the deflagration pressure–time curves of a hydrogen explosion was proposed. The deflagration parameters (pressure peak, duration, deflagration index, and impulse) of hydrogen–air mixtures with different hydrogen concentrations were experimentally investigated. The results show that the pressure curves calculated by the model are consistent with experimental data pertaining to a methane and hydrogen explosion. By comparison, the pressure peak and deflagration index are found to be influenced by the aspect ratio and surface area of vessels. The impulse and explosion times at fuel-lean hydrogen concentrations are greater than those at fuel-rich concentrations. When the hydrogen concentration is between 34 vol.% and 18 vol.%, the greatest explosion damage effect is formed by both the overpressure and the impulse, which should be considered for hydrogen explosion safety design in industrial production.
A series of methane-vented explosions were experimentally
investigated
in a 4.5 m3 rectangular chamber at P
0 = 100 kPa and T
0 = 298 K, and
the effects of ignition positions and vent areas on the external flame
and temperature characteristics were studied. The results indicate
that the vent area and ignition position significantly affect external
flame and temperature changes. The external flame is portioned into
three stages: an external explosion, a violent flame jet with a blue
flame, and a yellow flame venting. The temperature peak first rises
and then reduces with increasing distance. Rear ignition produces
the largest flame lengths and highest temperature, while front ignition
leads to the shortest flame and smallest temperature peak. The maximum
flame diameter occurs at central ignition. As vent areas increase,
the coupling effect of the pressure wave and the internal flame front
weakens and the diameter and peak of the high-temperature peak increase.
These results can offer scientific guidance for designing disaster
prevention measures and evaluating explosion accidents in buildings.
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