Overpressure

About: Overpressure is a research topic. Over the lifetime, 3236 publications have been published within this topic receiving 34648 citations.

Premixed methane/air flame propagating in an obstructed chamber with different BRs and spatial configurations

Abstract: The effects of obstacle blockage ratio (BR) and spatial configurations on premixed methane/air flame propagation are experimentally investigated by the high-speed video photography and pressure transducer. The results demonstrate that the flame shape changes, flame tip speed and deflagration overpressure in the initial stage are not affected by the obstacles with different BRs and spatial configurations. After the moving flame feels the obstacle, flame tip speed and overpressure increase significantly with increasing obstacle BR for center-installed obstacle. The first peak value of flame tip speed with bottom-installed obstacle is slightly larger than that with center-installed obstacle. Two-peak structure is observed in the curves of flame tip speed, and overpressure variation depends strongly on the second flame acceleration, which also explains the fact that deflagration overpressure with bottom-installed obstacle is smaller than that with center-installed obstacle with time ranging from t = 36 m to t = 90 m.

Air‐Blast Suppression as a Function of Explosive‐Charge Burial Depth

Abstract: The blast wave from buried explosions consists primarily of a pulse induced by the ground shock followed by another pulse when the explosive gases are vented to the atmosphere. The latter pulse provides the dominant contribution for the shallower burial depths. Air‐blast measurements made along the ground surface for 46 chemical explosive and 7 nuclear explosive detonations have shown the peak overpressure of the ground‐shock‐induced pulse to be about the same for chemical and nuclear explosions in basal rock as for chemical explosions in alluvial soil. The ground‐shock‐induced pulse has not been observed for nuclear explosions in soil. The peak overpressure from venting gases is about equal for chemical explosives in basalt rock and alluvial soil. Peak overpressures are higher for nuclear explosions in soil, in part because the cavity pressures at the time of venting are higher; peak overpressures are lower for nuclear explosions in rock, presumably because less gas is formed and because the pulse from venting gas coincides with the negative phase following the ground‐shock‐induced pulse, thus reducing overpressure amplitude. Measurements have been made over a sufficiently large range of charge burial depths that a pattern of air‐blast suppression with charge burial can be presented.