Study on the shock wave generated by underwater electrical explosion of Al wire coated with CuO powder

It is well-known that alumino-thermic reaction can release a massive amount of heat. In this paper, the heat released by Al/CuO was chosen as an additional energy to improve the shock wave generated by underwater electrical wire explosion. The Al wire coated with CuO powder was first prepared and exploded by a ~ μs time-scale pulsed power generator, and high-voltage probe and Pearson coil were used to record the potential difference and the pulsed current flowing through exploding wire, respectively. By analyzing electrical signals, we found that the existence of CuO coating layer impedes the rapid expansion of exploding wire, which indicates that the restrike of exploding wire will be delayed in theory. However, the restrike occurs earlier than uncoated Al wire, since the heat released by the alumino-thermic reaction changes the parameters of potential discharge channel. Using pressure probe to capture the pressure history at far-field (50 mm away from exploding wire), the results show that the impulse of shock wave is improved when the operation voltage was set to 5.0 kV; this is because the interval from the vaporization of metal wire to the restrike of exploding wire provides the time the alumino-thermic reaction needed. Meanwhile, numerical simulations were carried out to disclose the influence of coating layer on shock wave, and the results reveal that the amplitude of shock wave is improved at near-field, and the rising edge becomes steeper. Finally, possible mechanism of alumino-thermic reaction between Al wire and CuO powder was discussed, and a qualitative mathematical model was established to describe the process of heat release.