Effects of Water on Blast From the Simultaneous Detonation of 180 152 mm Shells

摘要

ARA was asked and funded by the Naval Facilities Engineering Service Center (NFESC) to perform calculations of the airblast resulting from the simultaneous detonation of 180 six inch (152 mm) naval artillery shells. The calculations were run within the geometry of the KLOTZ Club tunnel test site at Alvdalen, Sweden. This geometry includes two crossing tunnels with a chamber at the end of each and a single tunnel entrance. A berm was constructed just outside the tunnel entrance to provide absorption and deflection of fragments. A test was conducted at this facility with 180 six-inch shells in 1989. In September of 1996 this test was repeated with 2000 kg of water in the vicinity of the detonation. Results of the two tests showed some surprises such as higher pressures near the tunnel entrance when water was present. ARA was asked to make detailed first principles calculations that included the effects of water on the airblast. SHAMRC was used to make several three dimensional calculations of the two tests. SHAMRC includes the detonation process, the effects of accelerating, heating and vaporizing the water and propagation of the resulting airblast. Previous experience at Alvdalen, Sweden and at Magdalena, New Mexico had shown us that the response of the walls of the detonation chamber could be an important energy absorbing mechanism for large charges but was ignored for this relatively small loading density. The initial conditions for the calculations used two planes of symmetry through the charge, thus the detonation of the explosive in an equivalent of only 45 shells (245 kg.) was calculated. A bare charge calculation was run which ignored the effects of the steel casing of each shell. This calculation included three materials: air, detonation products, and solid explosive. The results of this calculation provide the initial conditions for a series of calculations that included increasingly larger portions of the tunnel system. A second calculational series include.