Semi-cylindrical shock waves and blade-shaped supersonic jets generated by underwater electrical explosions of wire arrays
摘要
We present the results of experimental studies and two-dimensional hydrodynamic simulations of underwater electrical explosions of semi-cylindrical wire arrays. In the experiments, a pulse generator delivers a current pulse of ~ 250 kA amplitude rising in ~ 1 µs to a 5-mm radius semi-cylindrical array of copper or aluminum wires. Experiment and simulation results display the generation of a radially symmetric and converging strong shock wave (SSW) and the generation of a blade-shaped supersonic jet (SJ) with a velocity reaching 1.6 km/s. Simulations predict that in the vicinity of the implosion axis, the density, pressure, and temperature can reach 1.5 g/cm3, 6 × 109 Pa and 500 K, respectively. Thus, this approach can be used for studies of properties of materials placed at the convergence axis or by interaction with the blade-shaped SJ with easy access of diagnostics. Additionally, the simulations show that the internal structure of the jet is not uniform, consisting of bubbles and voids that result in significantly smaller density than the normal density of water. Finally, explosions of arrays of different diameter wires result in the generation of converging SSW with satisfactorily uniform azimuthal distribution. This indicates a resistance positive feedback mechanism that stabilizes the explosion process across wires of different diameters.