Schematic of ‘Forest Flyer’ explosive launching system for shock physics projectiles.
Signals contributing to the causal angle .
States in the computation of the asymptotic angle .
Comparison of projectile flatness predicted from continuum dynamics simulations with different case materials and taper angles. 45° tapers used the original Forest Flyer design with a cylindrical section in the explosive charge; the other tapers were constant over the full length of the charge. The Al case with 20° taper gave much the same result as the steel.
Example free surface velocity histories from two dimensional continuum dynamics simulation of explosively launched projectile, suggesting shock formation and tension (Al case, multipoint initiation). High frequency noise is from Lagrangian marker particles drifting off the surface of the projectile.
Drive pressure histories predicted by one dimensional continuum dynamics simulations, for plane wave lens and multipoint initiation schemes, using the component thicknesses from the original Forest Flyer design and also for a thicker gap.
Pressure histories predicted at the midplane of the projectile, for plane wave lens and multipoint initiation schemes, using the component thicknesses from the original Forest Flyer design. The horizontal line is the spall strength for Al-6061.
Shock formation distances predicted as a function of drive pressure as predicted from one dimensional continuum dynamics simulations with multipoint initiation, using the component thicknesses from the original Forest Flyer design ( gap) and also for a thicker gap . The high frequency noise is from the use of a tabulated numerical calculation of the isentrope.
Comparison between proton radiographs showing Forest Flyer shape just before impact and projectile shape from continuum dynamics simulations. The calculated curvature of the rear surface matches well over the central . The thin fillet at the outside is visible further back in the radiograph. The leading edge at the outside of the projectile appears further advanced in the simulations.
Projectile acceleration performance for different cases and tapers. (For the plane wave lens initiated charges, of the explosive mass is TNT rather than PBX-9501.)
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