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Underwater electrical wire explosion is usually used as a source of underwater shock waves, and the generated shock wave intensity can be regulated by adopting a wire array. In this paper, the dynamics of the electrical explosion of two wires with different diameters connected in parallel were studied. The current flowing through each wire was measured to study the current distribution, and the self-emission image and laser backlight shadow image was obtained to observe the evolution of the wires. A numerical model was built to make explanations and predictions. The results showed that due to the presence of wire inductance and contact resistance between the wire and electrode, the wires are with different current densities and undergo asynchronous heating from the beginning of the discharge. Furthermore, the variation of current distribution among the wires was divided into six stages according to the moment the wire melted and exploded, and analyzed stage by stage. The unbalanced energy deposition results in obvious differences in thermal dynamic parameters, which explains the gradual "extinguishment" of the thinner wire in the self-emission image. [ABSTRACT FROM AUTHOR]

As a new method for generating strong underwater shock waves with rapid repetition frequency, the use of underwater electrical-wire explosion (UEWE) to drive insensitive energetic materials has attracted increasing research attention in recent years. Accordingly, equipment based on this new method have been developed. The ability to measure the stress produced by an UEWE on a device plays a very important role in optimizing the device performance. However, in conventional stress measurements, the spatial electromagnetic interference (EMI) produced by the discharge can affect the measurement accuracy or even damage the experimental instruments. In this study, a novel system for measuring stress in a strong electromagnetic field, based on a piezoelectric film and a conditioning circuit, was debugged and evaluated. Shielding was used to eliminate the intense EMI due to the strong electromagnetic field. Our simulation and experimental results demonstrate that the stress generated can be quickly determined by measuring the output voltage of the conditioning circuit. The new system can be used to measure the stress at the fluid–solid interface under a strong electromagnetic field environment. [ABSTRACT FROM AUTHOR]

Underwater electrical wire explosion (UEWE) is an efficient source of underwater shock waves (SWs). In order to efficiently simulate the interaction between the UEWE SW and structures, a coupled model that includes the electric circuit, the exploding wire and the surrounding water is established based on user-subroutines provided by the commercial explicit dynamics software ANSYS AUTODYN. The modeling starts from room temperature by using the tabular wide-range metal equation of state (EOS) and conductivity data. Experimental validation is performed with copper wires exploded by a μ s-timescale pulsed discharge. The numerical results show satisfactory consistency with experiments in terms of the current and voltage waveforms, the wire expansion trajectory, the evolution of SW front, the interaction between SW and electrodes and the SW pressure profiles. The main discrepancy lies in the SW amplitude that is ∼20% higher in the calculation and the possible reasons are discussed in detail. Based on this approach and with proper modifications to the metal EOS and conductivity data, the interaction between UEWE SWs and structures can be efficiently modeled in 2D and 3D for practical applications. [ABSTRACT FROM AUTHOR]

The underwater electrical wire explosion (UEWE) is an appealing source of underwater shock waves (SWs) with a high conversion efficiency from electrical energy to mechanical energy, good repeatability and controllability. Industrial applications are already seen in oil-well unblocking and stratum stimulation, and research is currently underway to apply UEWEs in electro-hydraulic forming, exploitation of unconventional gas and oil resources, etc. The emerging new applications call for a review on UEWE research from the perspective of an efficient SW source. This review paper considers the physical processes and numerical simulation methods, electrical and SW characteristics, and current and potential applications, and provides suggestions for future research directions. The code (XJ_UEWE01) developed by the authors to solve a coupling model of UEWE is included. The paper will provide students and researchers new to this field with an explanation of basic concepts of UEWE and a detailed overview of previous studies, and will aid research on UEWE applications, especially device development and parameter optimization. [ABSTRACT FROM AUTHOR]

A new approach has been presented herein to prepare nano titanium carbide based on the underwater electrical explosion approach. Scanning electron microscopy and x-ray photoelectron spectroscopy were used to investigate the morphology and composition of the electrical explosion products. A numerical model was established to investigate the nanoparticle formation process. The results show that the average diameter of the formed nanoparticles was ∼60 nm and approximately conformed to a lognormal distribution. Compared with the nanoparticles prepared by electrical explosion in gas, the nanoparticles prepared by the underwater electrical explosion had a smaller size distribution range and better sphericity. During the formation process of nanoparticles, the distribution of nanoparticles formed in a narrow temperature range near the specific temperature directly determined the characteristics of the final electrical explosion products. The specific temperature was ∼3400 K, which was also the specific temperature of the saturation ratio, the nucleation rate, the average diameter of the formed nuclei, the number of monomers, and the number of the formed nanoparticles. The diameters of nanoparticles obtained in the experiment were mainly concentrated between 50 and 70 nm, and the calculated diameters of the nanoparticles were mainly concentrated between 55 and 65 nm; therefore, the data obtained through the model were consistent with the experimental ones. These provide a way to synthesize the nano titanium carbide and a method to estimate their size and distribution, and it is hoped for understanding the evolution of the titanium wire underwater electrical explosion and the formation of nanoparticles. [ABSTRACT FROM AUTHOR]

Underwater electrical explosions of Cu wires were carried out on a microsecond time scale to produce underwater shock waves. Experimental results show that the radial density distribution of the water flow after restrike contains several oscillations, observed as ∼1 mm-spaced layers in the backlit streak images and laser shadowgraphs. The phenomenon is attributed to the partial reheating of the exploding product (EP) by an interior restrike arc, which stimulates a compression wave propagating back and forth radially in the EP. Simulations are used to support the interior breakdown scenario and to demonstrate that each reflection of the compression wave at the EP–water interface launches a weak shock into the water, forming a multilayer structure. As the surrounding metallic vapor is ionized due to radiation and thermal conduction from the arc, the highly conductive plasma channel continues to extend radially and launches the main compression wave, which drowns out the multilayers when the power injection is sufficiently high. [ABSTRACT FROM AUTHOR]