|M.Sc Student||Yanuka David|
|Subject||Generation of Strong Converging Shock Waves by Underwater|
Electrical Explosion of a Wire Array
|Department||Department of Physics||Supervisor||Professor Yakov Krasik|
|Full Thesis text|
The presented thesis is devoted to experimental and numerical studies of generation of converging strong shock waves which are produced by underwater electrical explosion of wire arrays supplied by a high-current pulse with a microsecond time scale duration.
The thesis involves two parts. The first part is related to the experimental and numerical investigation of converging shock waves generated by underwater electrical explosion of a spherical wire array, and the second part is dedicated to numerical investigation of an underwater electrical explosion of a planar wire array with different boundary geometries.
The explosions of the spherical wire array were carried out using a microsecond timescale high-current generator with stored energy of 3.6 kJ generating at its output a current pulse with rise time of ~1.1 s and amplitude of ~300 kA. The output current pulse was applied to a spherical array of Cu wires of different radii (20-40 mm), and different wire diameters (100-160 m). One-dimensional hydrodynamic simulations, coupled with the experimental data and equations of state for water and copper, were used to calculate the water parameters at the vicinity of implosion. The results of these simulations showed that one can expect to achieve the values of pressure, temperature and compression of water of 3.5 TPa, 18.5 eV and 8.75, respectively.
In the second part of the thesis, underwater electrical explosions of a planar wire array with two different boundary geometries were investigated using a two-dimensional hydrodynamic simulations coupled with equations of state of water. The explosion of the wires creates a shock wave which converges to the axis common to the walls. Two boundary geometries were considered, namely two straight walls and two parabolic walls. The purpose of this research was to show that the pressure and temperature of water obtained at the vicinity of implosion in the geometry with the parabolic walls could be higher than that of the straight walls due to faster convergence of the generated shock wave. In the second geometry, those walls, from side view, were shaped like parabolas. The results of carried out numerical simulations showed that indeed for the same energy deposited to the exploding wires, the values of the pressure and temperature of water obtained at the vicinity of implosion in the geometry with parabolic walls, is ~3 times and ~1.5 times greater than in the case of the straight walls.