Effects of circuit inductance on electrical and shock wave characteristics at underwater wire explosion

Abstract

Circuit inductance is an important parameter at underwater electrical wire explosion (UEWE) experiments as it closely relates to the energy deposition rate to the load wire. In this study, the circuit inductance was varied within a wide range from 1.55 μH to 93.2 μH by inserting inductive coils to study its effects on electrical and shock wave (SW) characteristics at UEWE. Experimental results showed that UEWEs using thinner wires were less affected by the increase of circuit inductance and the SW peak pressure several-cm away from the wire is not sensitive to the increase of circuit inductance if properly choosing the diameter of load wire: the maximum SW peak pressure obtained with varied diameter (constant energy storage and wire length) only saw a decrease of 30% as the circuit inductance increased by 60 times from 1.55 μH (0.3 mm diameter, 19 MPa) to 93.2 μH (0.2 mm diameter, 13 MPa). Hydrodynamic calculations were used to explain the experimental results. These results indicated that for a practical UEWE system, the energy storage can be far away from the load while keeping an acceptable loss of the capability of generating strong SWs, which greatly improves the flexibility of system designing for example by enabling much larger energy storage for certain harsh working environments.

Electrical wire explosion as a source of underwater shock waves

“…However, i w can be notably lower than i when a large (MA) current is conducted by the EP, as a large proportion of i is then shunted by a water plasma layer surrounding the wire. The last approximation made in equation (1) corresponds to neglecting the decrease of L w caused by the expansion of the exploding wire so as to avoid the detailed measurements of the EP expansion trajectory, and is generally reasonable for a microsecond UEWE with several kJ energy storage and roughly matched load [60]. Nevertheless, it is safer to estimate the contribution of idL w /dt based on specific circuit and load parameters.…”

“…The detailed experimental setup in this section is the same as in [60]. (6 µF capacitor bank, 13 kV charging voltage, 1.45 µH circuit inductance, 90 mΩ circuit resistance).…”

Two-dimensional simulation of microsecond-timescale underwater electrical explosion of a copper wire

“…The experiments were carried out on the UEWE platform as described in [33]. The pulsed power supply consists of a 6 µF pulsed capacitor, a three-electrode gas spark switch, coaxial cable of ∼4 m length, and the coaxial load target.…”

“…where u m and i m are respectively the measured voltage and current; L w0 is the initial wire inductance. The voltage components caused by wire inductance decreasing (i m dL w /dt) and the circuit resistance (R s i m ) are neglected [33].…”

Detonation of a nitromethane-based energetic mixture driven by electrical wire explosion

“…A schematic diagram of the experimental setup is shown in figure 1(a). Detailed circuit parameters can be found in [13]. The voltage and current were respectively measured by a Rogowski coil (Pearson 101) and Tektronix high-voltage probe (P6015A).…”