Study of the Penetration of Water by an Explosively Formed Projectile

摘要

The report describes a numerical modelling and experimental study into the use of explosively formed projectile (EFP) for water penetration as a potential method for neutralising seamines. Dyna2D was used to model a large number of EFP designs and a short list of candidates were selected for water penetration modelling. Experimental validation of the code prediction was undertaken using multiple flash radiography to define EFP shape, velocity and break up in water. In all, the numerical predictions show good correlation with experimental results, both above and beneath the water. Two nominated candidates were fabricated for water penetration study. They were both densely compacted EFPs, one with a velocity of 2.0 km/s, and the other, a slower projectile with a velocity of 1.5 km/s to avoid classic mass erosion as it enters the water. However, the EFPs failed to perform after bridging more than 2 to 3 charge diameters of water, after which the remaining projectile mass is insignificant or is too slow for seamine neutralisation operations.