Xinxin Wang

Motivated by the sustainable development goals, wind energy is significantly developed as an important renewable and clean energy source. Nevertheless, the problem of downtime due to icing of wind turbine blades in winter remains unsolved, resulting in a significant waste of wind resources. To address this issue, the author proposes a new shock wave de-icing method based on pulsed liquid discharge, and clarifies that micro-deformation and vibration of the blade layer are key factors. Ensuring that the liquid state and freezing point of the antifreeze solution are not affected by the discharge is key to extending the method to engineering applications. Typical organic antifreeze is evidenced to be unsuitable because it generates large amounts of gaseous products. In this paper, the physiochemical properties changes in typical inorganic antifreeze (calcium chloride, CaCl₂) after the occurrence of pulsed discharges are investigated. It is found that pulsed discharges in CaCl₂ antifreeze generate essentially no gaseous products (i.e., no obvious change in the medium state). In addition, it is found that the freezing point of CaCl₂ antifreeze does not increase, while the hydrogen ion concentration (pH value) decreases slightly after discharge. The underlying factors contributing to these pH value fluctuations are elucidated. It is worth noting that the color of the solution changes significantly after discharge, which is due to the reaction and ablation of the electrode material producing some solid products. This study is expected to deepen the understanding of pulsed discharges affecting the physicochemical properties of typical inorganic antifreezes, thus providing important theoretical guidance and practical reference for the selection of antifreezes in this innovative de-icing method.

Underwater electrical wire array explosions (UEWAEs) are used to generate converging shockwaves with controllable wavefront shapes and peak pressure through the interaction among multiple shockwaves. Due to the energy accumulation of converging shock waves, sub-megabar pressures can be achieved using a medium-scale pulsed power facility with only several kilojoules of energy. The high energy efficiency and flexible controllability of this method make it highly promising for applications in high energy density physics and material forming. In recent years, with advances in optical diagnostics and numerical simulation techniques, significant progress has been made in understanding the fundamental physical processes of electrical wire array explosions. Correspondingly, several new application scenarios have emerged. A comprehensive review of UEWAE is necessary to summarize these achievements and provide guidance for future developments in the field. This paper systematically reviews the latest advancements in the fundamentals, load optimization methods, and application scenarios of UEWAE, offering newcomers to this field a panoramic view of existing studies.

The acoustic characteristics of dc biased alternating arcs are widely applied in industrial fields such as welding. Argon, valued for its stability, ease of arc ignition, and low cost, is commonly used as the working gas. But the use of argon arc welding some metals, there are welding depth of weld is insufficient, low welding efficiency, and other problems. Consequently, in high-precision/reliability applications, attempts are being made to mix other gases (such as helium and nitrogen) with argon to improve welding performance. There has been no in-depth research on the acoustic characteristics of arcs in mixed gases. In this article, an experimental study was carried out on the arc sound in argon/helium and argon/nitrogen mixtures, which are widely used. It is found that the ratio of the gas mixtures seriously affects the arc morphology, discharge characteristics, and acoustic wave characteristics. The acoustic characteristics of the arc depend on two main factors: the amount of electric power injected into the arc, and the arc’s electric-acoustic conversion efficiency. When the proportional distribution of the gas mixture is sufficient to affect either parameter, the sound changes significantly. However, the opposite effects of these two factors may result in essentially unchanged sound pressure in certain cases (e.g., pure helium and pure argon). This study clearly identifies the differences in arc sound and its physical nature for different gas mixture ratios and provides guidance for gas ratio regulation in industrial applications.

Blade icing poses a significant challenge to the safe and stable operation of wind turbines. The use of the thermal effect of surface dielectric barrier discharge (SDBD) plasma is regarded as a promising solution to this problem. Nevertheless, the application of this method is limited by inadequate understanding of the influence patterns and underlying mechanisms of airflow on the SDBD thermal effect. This study systematically investigates the influence of airflow velocity, direction, and voltage parameters on the thermal effect of an SDBD array using a combined experimental and simulation approach. The results indicated that airflow significantly suppresses the surface temperature rise of the SDBD discharge device above a certain velocity. Furthermore, an increase in the angle between the incoming flow direction and the discharge device has been shown to reduce convective heat transfer efficiency, leading to a more pronounced surface temperature increase. Finally, it is evident that elevating the voltage amplitude and pulse frequency serves to enhance the thermal effect. The present study provides a theoretical foundation for the optimization of SDBD anti-icing/deicing technology on wind turbine blades, thus offering a basis for parameter adjustment in practical applications.

Low-temperature plasma jet is a newly proposed atmospheric pressure gas discharge technology in recent years, which has a wide range of application prospects in the fields of biomedicine, material processing, environmental treatment and so on. However, the low application efficiency in some fields caused by the small cross-section size of low-temperature plasma jet is a more prominent problem. Although some researchers have tried to use arrays made up of multiple jets working in parallel at the same time, this also involves additional gas paths and complicated operation. The aim of this study is to propose an approach for the generation of an integrated large cross-section low-temperature plasma jet: using a multilayer coaxial structure. The electrical and airflow fields of the multilayer coaxial structure are first computationally optimized to avoid the formation of unstable and inhomogeneous discharge plasma jets. The designed integrated large cross-section low-temperature plasma jet is then subjected to an experimental study to observe the effects of the electrical and airflow parameters and to photograph its emission spectral characteristics for comparison with conventional jets. The results show that the physical mechanisms and laws are consistent with those of conventional low-temperature plasma jets and therefore do not pose additional negative problems for applications. This study provides a new solution for increasing the cross-section size of low-temperature plasma jets and helps to promote their large-scale practical applications.

Converging shock waves generated by underwater electrical wire array explosions can achieve extremely high pressure conditions in a relatively compact device, which has important value in the high-energy-density physics research. The energy conversion efficiency and the amplitude of shock waves depend on the matching relationship between wire arrays and pulse generators. Previous studies usually optimize the number of wires in the wire array by splitting the optimal single wire load. In this paper, we compared the underwater electrical explosion processes of wire arrays having the same total cross-sectional area but different splitting numbers based on one-dimensional magneto-hydrodynamic simulations. The simulated voltage and current waveforms showed that the electrical explosion cannot remain in the matched mode by splitting the optimal single wire. The thermodynamic evolution of exploding wires indicated that the primary reason for deviating from the matched electrical explosion is the differences in expansion rates. To explain these differences, a similarity law for the split wire arrays was introduced to find the conditions of keeping the same thermodynamic evolution. Finally, a novel optimization strategy for the wire array load was proposed based on this similarity theory.

In the context of global climate change, wind power has received considerable attention as a significant clean energy source. Nevertheless, the problem of wind turbine blade downtime due to icing, which occurs in the fall and winter seasons under conditions of high humidity and low temperature, remains an urgent problem that must be addressed. In addressing this challenge, a novel method of pulsed liquid discharge shock wave de-icing has been proposed, offering distinct advantages such as reduced energy consumption and expedited response times. Ensuring that the liquid phase medium remains in the liquid state under low-temperature conditions is paramount to facilitating the smooth generation of shock waves during liquid phase discharge. Consequently, the selection of an appropriate antifreeze becomes pivotal for the successful implementation of this technology. However, it was found in this paper that pulsed discharge in ethylene glycol antifreeze (C2H6O2 + H2O) would generate significant amounts of gaseous products, altering the medium's environment and impacting subsequent discharges and shock wave generation. The gaseous products and liquid residues of ethylene glycol antifreeze after pulsed discharge were measured and analyzed by combining mass spectrometry and chromatography to determine the main product compositions of ethylene glycol antifreeze after pulsed discharge and to deeply analyze the decomposition paths of ethylene glycol antifreeze under pulsed discharge conditions. This study is expected to enhance the comprehension of the chemical process of pulsed liquid discharge in typical organic antifreeze, thereby providing significant theoretical guidance and practical reference for the selection of antifreeze in the subsequent pulsed liquid discharge shock wave de-icing method.

The light emitted by gas discharge plasma is often used as a light source for precision optical instruments. The measurement precision and accuracy of these precision instruments are greatly affected by the ambient temperature. In fact, although low-pressure glow gas discharge plasma is often referred to as “low-temperature plasma”, it may also have thermal effects under prolonged operation. There is a lack of research on the thermal effects of low-pressure glow discharges and the process of its heat transfer through the discharge tube. In this article, a 2-D axisymmetric fluid model is established, coupling multiphysics fields such as discharge plasma, laminar flow, and heat transfer. The thermal effect and heat transfer of He/Ne gas mixture glow discharge at low pressure are investigated. Studies show that, after the discharge has lasted for a certain period of time, the temperature in the gas discharge region is significantly elevated and can reach tens or hundreds of kelvins. The temperature of the glass tube may also increase by more than 20 K under certain discharge parameters. The current-limiting resistance, the gas pressure, and the He/Ne gas ratio have a large influence on the thermal effect of the gas discharge. Therefore, the thermal effect of gas discharge applied as a light source in precision optical instruments cannot be ignored and needs to be regulated and designed for specific situations. This article contributes to a deeper physical understanding of the thermal effects of low-pressure glow discharges and provides guidance for their optical application.

In response to climate change, an increasing number of countries are setting carbon-neutral and net-zero emission targets. Clean energy is receiving wider attention. Many wind power stations are located in high mountains with abundant wind resources, and their blades have serious ice-covering problems in winter. Currently, there are no widely available solutions. In order to solve this problem, this article proposes a new de-icing method based on shock waves generated by pulsed liquid discharges. This method has never been proposed and experimented with before. The advantage of this method is energy efficiency, requiring only a tiny amount of energy to break up the ice. The structure of the new de-icing device was first designed and tested with liquid discharges. It was verified with unsecured nails that the shock wave generated by the pulsed liquid discharges could be transmitted to the outer surface of the blades. Then, the de-icing experiments were carried out in different blade arrangement directions to confirm the effectiveness of the new de-icing method. Finally, the propagation of the shock wave after its generation with its resulting elastic microdeformation process of the blade is calculated. This study provides a new solution idea for the ice-covering problem of wind turbine blade, which is of great significance to the sustainable development of human society.

An energy-efficient method is developed to generate shock wave (SW) from underwater electrical wire-array explosion. By changing the wire connection of cylindrical wire array, parallel is found usually not the suitable connection of wire array to generate SW at a fixed energy. The suitable connection of wire array is determined by initial energy. At a given initial energy, resistance matching between load and external resistance is an important factor to generate a SW, and the corresponding discharge current is critically damped discharge.