Modeling of metallic jet production using pulsed underwater discharges

Summary form only given. Pulsed electrical discharges in water can generate high pressure shocks. We have used such shocks to accelerate thin metallic foils to velocities of 1.4-1.6 km/sec. The foils turn into high-velocity jets which can perforate metal sheets. The design and performance of this system is discussed in a companion paper in this conference. In this paper, we report on computer simulation of such systems. The simulations have been done using a two-dimensional, time-dependent lagrangian hydrodynamic code which allows for strength-of-material effects. The code uses the Steinberg-Guinan rate-independent expression for the dependence of yield strength and shear modulus of foil material (Al/Cu) on temperature, pressure and plastic strain. Tabulated equations of state are used for water, the foil material, and the casing. The simulations use experimentally measured voltage and current data to generate the input power versus time waveform. The spatial distribution of the power deposition density depends on underwater arc dynamics. In the absence of a comprehensive model for the arc, we assume different spatial waveforms as a ´tunable´ factor to match experiments. The code yields the temporal evolution of the shape and velocity of the jet. It also yields the spatio-temporal profiles of density, temperature and velocity of the working fluid (water) and the steel casing. We find that, with suitable tuning of the power deposition density, code predictions of foil velocity match reasonably well with experiment. In this paper, we present a comparison of simulation results with experiment. We also report on optimization studies for this system.