title: Explosively driven air blast in a conical shock tube.
abstract: Explosively driven shock tubes present challenges in terms of safety concerns and expensive upkeep of test facilities but provide more realistic approximations to the air blast resulting from free-field detonations than those provided by gas-driven shock tubes. Likewise, the geometry of conical shock tubes can naturally approximate a sector cut from a spherically symmetric blast, leading to a better agreement with the blast profiles of free-field detonations when compared to those provided by shock tubes employing constant cross sections. The work presented in this article documents the design, fabrication, and testing of an explosively driven conical shock tube whose goal was to closely replicate the blast profile seen from a larger, free-field detonation. By constraining the blast through a finite area, large blasts (which can add significant damage and safety constraints) can be simulated using smaller explosive charges. The experimental data presented herein show that a close approximation to the free-field air blast profile due to a 1.5 lb charge of C4 at 76 in. can be achieved by using a 0.032 lb charge in a 76-in.-long conical shock tube (which translates to an amplification factor of nearly 50). Modeling and simulation tools were used extensively in designing this shock tube to minimize expensive fabrication costs.
authors.affiliation: U.S. Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005, USA.
authors.forename: Joel B
authors.initials: JB
authors.lastname: Stewart
authors.affiliation: U.S. Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005, USA.
authors.forename: Collin
authors.initials: C
authors.lastname: Pecora