Focusing on Acoustic Waves in a Non-Uniform Atmosphere
MATERIALS RESEARCH LABS ASCOT VALE (AUSTRALIA)
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The blast scaling principle by charge weights may often produce gross errors in the estimation of overpressures at significant distances from a shot site. The principle ignores weather conditions and assumes a homogeneous atmosphere. Weather conditions may cause variations in the velocity of sound which allows the atmosphere to refract sound waves and act as an acoustic lens. Certain weather conditions such as temperature inversions may allow an acoustic focus many kilometers away from a shot site. Acoustic propagation from a noise producing installation has been mathematically modelled to assist in the prediction of anomalous overpressures by acoustic focusing. A computer model, REFFOCUS was developed to illustrate foci in a vertically inhomogeneous, non- turbulent, moving atmosphere. The model is produced from sound velocity profiles derived primarily from temperature and wind shear profiles.
- Atmospheric Physics