Climatological assessment of explosion airblast propagations. [Temperature dependence]

Conference · Thu Jan 01 04:00:00 EST 1987

OSTI ID:6150793

Reed, J W

Sound waves or explosion airblast waves are refracted by the atmosphere depending upon temperature-dependent sound speeds and winds at various altitudes. In comparison with propagation expected from a spherical explosion overpressure-distance function, long-range overpressures (below about 2 kPa) may be attenuated by a strong decrease (gradient) in sound velocity with height; they may be enhanced by an inversion or increasing sound velocity with height; or there may be blast focusing by as much as 3 to 5X from complex sound velocity structures. In general, for a wave passing through a layer where sound velocity decreases with height, wave normals (rays) are curved upward away from ground, so that overpressures are subject to excess attenuation compared to undistorted radial propagations from an assumed model explosion. In a layer where sound velocity increases with height, shock rays are curved downward toward the ground. When they strike ground, they are almost perfectly reflected, at least for the low frequencies and long wave lengths of most explosion tests, and follow repetitious paths. At moderate to long ranges, the result is a restriction to near cylindrical wave expansion, rather than spherical, with an associated amplification of wave overpressure, by comparison with an undistorted spherically expanding wave. In the more complex dogleg case, with a decreasing sound velocity strata above the surface capped by a layer of increasing sound velocities (to a value higher than at the surface), the result may be a folding of the wave front to form a caustic (in 3-D) or a focus that may reach the ground. Very strong overpressure amplifications may develop in such foci; 5X overpressure amplifications (25X in energy flux) have been recorded.

• Research Organization: Sandia National Labs., Albuquerque, NM (USA)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 6150793
• Report Number(s): SAND-86-2180C; CONF-870991-1; ON: DE87010510
• Country of Publication: United States
• Language: English

Related Subjects

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE
450100* -- Military Technology
Weaponry
& National Defense-- Chemical Explosions & Explosives
ATMOSPHERIC EXPLOSIONS
ATTENUATION
BLAST EFFECTS
DAMAGE
EARTH ATMOSPHERE
EXPLOSIONS
INHIBITION
OPENINGS
OPTICAL PROPERTIES
PERFORMANCE TESTING
PHYSICAL PROPERTIES
RECOMMENDATIONS
REFRACTIVITY
SOUND WAVES
TEMPERATURE EFFECTS
TESTING
VELOCITY
WAVE PROPAGATION
WIND
WINDOWS