Explosive gas blast: The expansion of detonation products in vacuum

Abstract

A series of 0.2- to 3-gm HNS charges were detonated in vacuums of 10 -3 to 10-5 Torr. The resultant freely expanding, detonation product, gas blast achieves terminal velocities of 8 to 12 km/sec within 3 to 5 μsec after the detonation wave arrives at the free surface. Measured pressure profiles display rise times to maximum stagnation ("reflected shock") pressure varying from ∼30 μsec, 20-cm away from a 2.6-gm charge, to ∼185 μsec, 127-cm away from 0.2-gm charge at 10-5 Torr. Rise times were generally shorter at 10-3 and 10-4 Torr; the 10-5 Torr values agree with numerical calculations. Using cube root scaling of charge mass, the observed peak reflected pressure as a function of range may be represented by p=6.5×105 (bar) r′-3.5, where r′ the ratio of the range to the equivalent charge radius. © 1971 The American Institute of Physics.