The prediction of blast wave overpressure using scaled distance calculations use the charge mass and radial distance variables and assumes that the blast wave is isotropic. Simulations and empirical studies demonstrate that altering the charge geometry results in a significant deviation in overpressure vs orientation. While this effect has been measured for cylinders, truncated cones, and cubes, the mechanisms driving geometric blast wave product anisotropy have not been well defined. Velocity vectors plotted from computer simulations in this study show an isotropic radial flow from the cylindrical charges, while the prismatic charges with rectangle, triangle, and five-point star cross sections had significant anisotropy and are overdriven normal to the sides of the charge and underdriven at the corners. The radial expansion of the rim of the dent is measured at the corners and normal to the sides of the charges as an indicator of radial energy distribution and particle flow during breakout. The depth of the dents shows a linear relationship with the breakout radii of the charges with an R2 value of 0.99. The radial displacement of the dent rim from the perimeter of the explosive charge is uniformly 5.5 mm around the cylindrical charge but is up to 1.5 times than normal to the sides of the prismatic charges and zero at the outside corners indicating an energy flow from the detonation wave toward the initial breakout locations.
K. Williams and C. E. Johnson, "Investigating Anisotropic Blast Wave Parameters Near the Explosive-Air Boundary using Computer Simulation and Experimental Techniques with Varying Charge Geometry," Journal of Applied Physics, vol. 130, no. 20, article no. 205902, American Institute of Physics (AIP), Nov 2021.
The definitive version is available at https://doi.org/10.1063/5.0068877
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28 Nov 2021