Blast Wave Phenomena
Is an incident involving the violent release of energy created by detonation of an explosive device. The sudden and intense pressure disturbance is termed the “blast wave.” The blast wave is characterized by an almost instantaneous rise from ambient pressure to a peak incident pressure (Pi). This pressure increase or “shock front,” travels radially outward from the detonation point, with a diminishing velocity that is always in excess of the speed of sound in that medium. Gas molecules making up the front move at lower velocities. This velocity, which is called the “particle velocity,” is associated with the “dynamic pressure,” or the pressure formed by the winds produced by the shock front. As the shock front expands into increasingly larger volumes of the medium, the incident pressure decreases and, generally, the duration of the pressure-pulse increase. If the shock wave strikes a rigid surface (e.g., a building) at an angle to the direction of the wave’s propagation, a reflected pressure is instantly developed on the surface and this pressure rises to a value that exceeds the incident pressure. This reflected pressure is a function of the incident wave’s pressure and the angle formed between the rigid surface and the plane of the shock front.
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Famous quotes containing the words blast, wave and/or phenomena:
“When autonomy is respected, the two-year-old does not carry this unfinished task into later stages of growth. In adolescence, the youngster will again concentrate on independence, but he won’t have to blast the roof off the second time around if it is already well established.”
—Dorothy Corkville Briggs (20th century)
“I sometimes compare press officers to riflemen on the Somme—mowing down wave upon wave of distortion, taking out rank upon rank of supposition, deduction and gossip.”
—Bernard Ingham (b. 1932)
“The phenomena of the year take place every day in a pond on a small scale. Every morning, generally speaking, the shallow water is being warmed more rapidly than the deep, though it may not be made so warm after all, and every evening it is being cooled more rapidly until the morning. The day is an epitome of the year. The night is the winter, the morning and evening are the spring and fall, and the noon is the summer. The cracking and booming of the ice indicate a change of temperature.”
—Henry David Thoreau (1817–1862)