Non-Ideal Airblast Phenomenology Program. Volume 2. Thermal Precursor Analysis, Moist-Soil Response to Brief Intense Radiative Heating.
Abstract
This theoretical study estimates the distribution of temperature, and of lofted particles (if any), which, for various soil conditions, would prevail at shock arrival. The distribution of sound speed is quantitatively characterized with height at shock arrival, with implications for shock structure. The amount of particulate matter that is lofted sensitively depends on the particle-size distribution. Particles with characteristic size greater than 100 microns are held by gravity against a one-meter-per-second gaseous stream, whereas material of one-tenth that size readily accompanies the stream. The capacity of steam to fluidize (unconsolidated) soil grains has significant consequences for the speed of sound, since modest dust loading countervails temperature enhancement in establishing the equilibrium sound speed of the medium. For an average flux of 400 W/sq-cm over 1-2 s for a soil with water saturation 0.2, and with extinction coefficient 6/cm for light in the visible, would lead to a sound speed of roughly 1.5 times that of ambient air over roughly an 8-m-high near-ground layer for soil with particles larger than 60um; neither such sound speed enhancement in, nor such thickness of, the thermal layer is anticipated for a soil of fines.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 30, 1986
- Accession Number
- ADB118436
Entities
People
- D. J. Chang
- F. E. Fendell
- G. F. Carrier
- M. P. Bronstein