Electromagnetic Rail Research Articles

Research on the anti-ablation performance of TiC particle reinforced aluminum matrix composite coating

During the electromagnetic rail launching process, the severe ablation of the armature caused by the arc can easily lead to launch failure. Therefore, it is necessary to study methods of enhancing the anti-ablation property of the armature. One effective method is to prepare metal-ceramic composite coating on the surface of aluminium alloy armature. This paper conducts molecular dynamics simulation on the ablation protection effect of TiC particle reinforced aluminum matrix composite coatings on the aluminum armature substrate. By applying a surface Gaussian heat source to simulate the arc ablation effect, the micro-enhancement mechanism of TiC particles is analyzed through the depth of ablation craters, material mass loss, and the evolution of TiC particle morphology. The results show that the degree of material ablation intensifies with the increase of arc discharge power. The composite coating helps to improve the anti-ablation performance of the armature, and the anti-ablation performance first increases and then decreases with the increase of TiC mass fraction. The results can provide a theoretical foundation and technical support for optimizing design of anti-ablation performance of armature materials.

A Novel Inductive Gradient Calculation Method for Electromagnetic Rail Launcher and Its Optimization

A Novel Inductive Gradient Calculation Method for Electromagnetic Rail Launcher and Its Optimization

Research on the Ablation Resistance of TiC Particle-Reinforced Aluminium-Based Composite Coatings on Armature Surface

The work aims to enhance and modify the armature surface in electromagnetic rail launch systems and improve its anti-ablation performance to better resist the impact ablation effects of high-temperature and high-speed arcs during the electromagnetic rail launch process and improve launch reliability. TiC particles are widely selected as metal material reinforcements, with advantages such as high melting points and high hardness. In this paper, the arc impact model of pure aluminum alloy and the arc impact model of TiC particle-reinforced aluminum-matrix composite coating–pure aluminum alloy were constructed based on molecular dynamics simulation. The ablation resistance of the material was evaluated by analyzing the depth of arc impact, the mass loss of the model, the number of gasification atoms, and the surface temperature of the material. The protection mechanism of the modified layer on the substrate was revealed by analyzing the damage degree of the surface and subsurface of the material after arc impact. The results showed that the strengthening mechanism of TiC particle-reinforced aluminum-matrix composites included fine grain strengthening, dispersion strengthening, dislocation strengthening, and so on. Covering TiC particle-reinforced aluminum-matrix composite coating on the surface of aluminum alloy armature is helpful in improving its ablation resistance. The research results can provide a theoretical basis and technical support for the modification design and performance control of electromagnetic rail armature.

Study on the active cooling effect and convective heat transfer performance inside the rail

In order to study the impact of different influencing factors on the active cooling effect of electromagnetic rail. The effects of the flow velocity of cooling medium, the geometric shape of the cooling channel, the cooling water inlet temperature and the nanoparticle mass fraction on the cooling effect of rail are experimentally investigated. The results indicate that increasing the flow velocity of cooling medium can enhance the heat transfer effect. But when the flow velocity exceeds 2 m/s, further increasing the flow velocity has little effect on enhancing heat transfer, and the correlation between the Nusselt number and the Reynolds number has been obtained and expressed as Nu=0.316Pr1/3Re0.530. Among the three cooling channel geometries studied in this article, square channel has the best cooling effect. The inlet temperature of cooling water has little effect on the convective heat transfer coefficient, but has a significant impact on the thermal equilibrium temperature of the rail. The mass concentration of nanoparticles has a significant impact on the cooling effect of the rail. The larger the mass fraction of nanoparticles, the greater the convective heat transfer coefficient, and the lower the rail peak temperature after reaching thermal equilibrium. However, if the concentration of nanoparticles continues to increase, the effect of enhancing heat transfer will gradually weaken.

Research Progress on Surface Damage and Protection Strategies of Armature-Rail Friction Pair Materials for Electromagnetic Rail Launch.

Electromagnetic rail launch technology has attracted increasing attention owing to its advantages in terms of range, firepower, and speed. However, due to electricity-magnetism-heat-force coupling, the surface of the armature-rail friction pair becomes severely damaged, which restricts the development of this technology. A series of studies have been conducted to reduce the damage of the armature-rail friction pair, including an analysis of the damage mechanism and protection strategies. In this study, various types of surface damage were classified into mechanical, electrical, and coupling damages according to their causes. This damage is caused by factors such as mechanical friction, mechanical impact, and electric erosion, either individually or in combination. Then, a detailed investigation of protection strategies for reducing damage is introduced, including material improvement through the use of novel combined deformation and heat treatment processes to achieve high strength and high conductivity, as well as surface treatment technologies such as structural coatings for wear resistance and functional coatings for ablation and melting resistance. Finally, future development prospects of armature-rail friction pair materials are discussed. This study provides a theoretical basis and directions for the development of high-performance materials for the armature-rail friction pair.

Механическое взаимодействие метаемого тела со стенками канала рельсового электромагнитного ускорителя. Численное решение

The vibration of the accelerator rails under the action of electromagnetic forces, the right boundary of which is moving along with the armature along the barrel bore, is considered. The rail accelerator is simply considered as a Bernoulli-Euler beam of finite length, lying on a viscoelastic foundation, with cantilever support from the side of the accelerator breech. The rail vibration is described by a differential equation in partial derivatives of the fourth order in coordinate and the second order in time. The equation is solved numerically by combined method: finite differences in time and finite elements in coordinate. A comparison of the results of numerical calculations with an analytical solution showed that the developed code evaluates the behavior of the rail well under the influence of an EM load moving along its length along the entire trajectory of the accelerated body. Using the developed code, the influence of the current profile in the accelerator circuit and the foundation parameters on the dynamics of bending waves arising and propagating in the rail, the position and magnitude of the maximum rail deflection was studied. It is shown that it is possible to select a current profile that minimizes the rail accelerator deflection during acceleration. It is also found that the choice of the optimal current profile has no less effect on the maximum rail deflection than improving the parameters of the accelerator foundation. The calculation results may be useful in the design of an electromagnetic rail accelerator.

Understanding the behaviour of magnetic field distribution of railgun under transient conditions using finite element method

The magnetic field distribution in the rails is a crucial factor in comprehending railgun behaviour. The projectile's rapid movement has a significant impact on the magnetic field. If the dispersion of the magnetic field conclusions regarding the conductors are known suitable methods can be used to sketch the magnetic field distribution. The railgun operates on the premise that a high current flow through the rails and armature will create a strong magnetic field. As a result, before designing magnetic shielding, it is necessary to study the features of the magnetic field distribution. The shape of rail and armature cross section is very essential in rail gun design as it determines the magnetic field distribution over rail and armature. The rail gun geometries with rectangular, convex and concave rail cross-sections are compared and simulated using finite element method (FEM). This method is used to determine the magnetic field distribution over rail and armature by sweeping armature position for different rail cross sections. It is observed that for the different rail/armature shapes like rectangular, convex and concave shapes, the C shaped convex armature possesses strong magnetic fields with minimum current density concentration at the throat and trailing end of the armature. From simulation, it can be shown that the magnetic flux density is a descending function of the central angle. The electromagnetic (EM) rail gun launching mechanism was therefore proven to be compatible with the circular concave armature.

Investigation on the microstructure evolution and mechanical properties of electromagnetic rail material in a launch environment

The failure issue of electromagnetic railgun rails is a widely researched problem, but effective research methods are lacking in studying the microstructure of rail materials. The high current and high strain rate tensile (HCHST) testing platform was designed to simulate the high current density and high strain rate deformation service conditions of pure copper rails used in electromagnetic guns. The microstructural and mechanical properties of commercially pure copper were analyzed using TEM and EBSD under high current density (2680 A/mm2) and various high strain rates (ε̇=3404s−1,ε̇=6808s−1)using the HCHST test platform. The obtained results were then compared with those obtained from the as-received state and the quasi-static current-assisted tensile (QCAT) test. The findings indicate that the deformation mechanism of pure copper specimen under HCHST is similar to that of QCAT, where dislocation and slip are the main mechanisms. However, distinct differences in microstructure were observed. Specifically, a significant number of dislocation walls were present in the grains under QCAT, whereas numerous dislocation cells were formed in the grains under HCHST. In the high-current density environment of 2680 A/mm2, as the strain rate increased, the number of dislocation cells increased while their size decreased. The grains became extremely refined, and the KAM value also increased. Furthermore, the Vickers hardness of pure copper significantly improved after undergoing the HCHST. Based on the experimental findings, it was observed that during the service process of the pure copper rail in electromagnetic railguns (under the influence of high current density and high strain rate deformation), the surface of the rail material experienced significant dislocation entanglement. This resulted in a significant increase in the strength and hardness of the surface of the rail with high strain rate deformation. However, the uneven distribution of strength and hardness throughout the surface layer of the rail eventually made it more susceptible to deformation and failure.

Research on the Contact Characteristics Between Armature and Rail of the Enhanced Electromagnetic Rail Gun Based on the New Aluminum Alloy Armature

Research on the Contact Characteristics Between Armature and Rail of the Enhanced Electromagnetic Rail Gun Based on the New Aluminum Alloy Armature

Analysis and Design Considerations of Input Parallel Output Series-Phase Shifted Full Bridge Converter for a High-Voltage Capacitor Charging Power Supply System

Capacitor charging power supply (CCPS) is used for impulse-power applications such as electromagnetic rail guns, flash lamps, medical sterilization, and rock crushing, among many other application fields. This paper describes the design and analysis of an Input Parallel Output Series-Phase Shifted Full Bridge converter for CCPS. The proposed system has a low output current ripple to improve the lifetime of the high-voltage pulsed capacitor. Design considerations of topology's electrical parameters such as HF transformer's leakage inductor and output inductor for the CCPS application are presented. The intermediate DC-link capacitance is provided as an energy storage element to minimize the disturbances (power variation) on the source for the CCPS application. Analysis and sizing of the capacitance for two different charging methods are analyzed and compared. A controller design procedure for the Active Front End Converter (AFEC) is also included to ensure near-constant power drawn, rejecting the load disturbances. Finally, a complete design procedure for the whole CCPS system is presented. Design and simulation results are presented for a rated system, followed by experimental results from a scaled-down hardware prototype to validate the design.

Characterization of magneto-thermo-hydrodynamic lubrication of metal liquid film at armature/rail interface

Utilizing the magneto-thermo-hydrodynamic lubrication theory, this study investigates the armature/rail(A/R) interface under high-intensity currents and transient high-temperature conditions. A magneto-thermo-hydrodynamic lubrication model is established using the finite difference method, coupling electromagnetic field, temperature field, and hydrodynamic lubrication theory, to depict the lubrication mechanism of the A/R interface under the influence of electromagnetic and thermal interactions. The characteristics of magneto-thermal diffusion for the armature/ rail, and the dynamic lubrication properties of the metal liquid film at the interface, are analyzed, to investigate how to improve the contact state of the A/R interface and enhance the stability of the electromagnetic rail launch. The findings are of significant importance for predicting frictional and thermal losses at the A/R interface and enhancing its performance.

Design and Simulation of a Slice-rail and Cylindrical for Multi-Projectile Electromagnetic Launchers

In Electromagnetic launcher (EML) research, beside reasonable L' and high muzzle velocities, there are several key features including multi-turn launching, low field intensity in payload position, high frequency shooting, less unwanted radiation, and so on. Attaining a solution might be feasible by a different structure. In this paper we have studied unequal curved electromagnetic rail launchers (EMRLs) as slice and cylindrical multi-projectile electromagnetic launchers, and the inductance gradient (L') of these structures has been calculated. Making multi-projectile EMRLs using a slice-rail structure is much easier than other plane methods. With a cylindrical multi-projectile EMRL, higher shooting frequency is more feasibly attained and there is no limit on the number of launchers at the same time. High temperature spots which are the result of high velocity and high current density distributions end in intense destructive erosion. Decreasing intense erosion in electromagnetic launcher structures will be more economical and provide greater reliability, therefore resulting in more applications for EMLs especially commercial ones. In parallel electromagnetic launchers, these points and areas are not omissible. In cylindrical EMRLs the problem of high current density distributions and its consequent erosion is significantly decreased because of the uniform distribution of current in its symmetric structure.

Study of Dynamic Inductance Gradient of Augmented Electromagnetic Rail Launcher Considering High-Speed Motion of Armature

The rail inductance gradient is an important parameter of the electromagnetic launcher. The calculation of its value is important for the design of the launcher structure and for predicting the motion behavior of the armature. The current research on the inductance gradient analysis method of the electromagnetic rail launcher mostly does not take into account the effects of launcher size and current diffusion. This method cannot describe its dynamic characteristics, and it results in a large error compared with the actual launch. Therefore, the paper first establishes an electromagnetic rail launcher armature motion model to obtain the rail velocity skin depth under a U-shaped armature. Second, an analytical method for calculating the inductance gradient based on the dynamic skin depth of the rail is obtained, which takes into account the launcher size and velocity skin effect. Finally, the experimental results verify the correctness and accuracy of the method to achieve an accurate prediction of armature speed.

An Enhanced Electromagnetic Rail Propulsion Design Based on Current Self-Guiding

An Enhanced Electromagnetic Rail Propulsion Design Based on Current Self-Guiding

A Review of the Computational Investigation of Three-Dimensional Transient Magneto-Thermal Coupling Characteristics of Electromagnetic Railgun Armature and Rail in High-Speed Sliding Electrical Contact

In order to investigate the dynamic process of electromagnetic field distribution, temperature change and the deformation during the launching process of electromagnetic railgun. It is necessary to conduct a three-dimensional coupled electromagnetic-temperature-structure analysis of the rail and armature, which requires the establishment of the corresponding multi-physics field model and the use of appropriate software and algorithms to complete the relevant simulation calculation and solution results. Based on this, this paper summarizes the current domestic and foreign research methods for multi-physics field characteristics under sliding electrical contact conditions, analyses the advantages and disadvantages of each method, and focuses on the updates of the three-dimensional finite element program EMAP3D based on Lagrangian description and the advantages of multi-field coupling. Finally, several considerations and operable spaces for multi-physics field coupling simulation are summarized to provide technical support for subsequent studies on multi-physics field characteristics for high-speed sliding electrical contact condition.

Parametric analysis and design of the initial contact state of a 400kA pulsed current C-armature

As a key component of an electromagnetic rail launcher, the armature plays a vital role in the performance of the electromagnetic launch. In order to solve the contact area and structural design problems of C-type armatures under large pulse current conditions, the material and initial contact state of a certain calibre C-type armature are studied, and the initial structural parameters of C-type armatures under 400kA through-current capacity and four times the calibre loading position constraints are analysed and calculated, together with the contact characteristics of armatures made of 6061-T6 and 7075-T6 aluminium alloys, to form At the same time, the parametric design of the C-type armature was carried out on the basis of the initial structural parameters, and the variation laws of contact stress, contact deformation, preload force and contact area were studied for different armature lengths, armature tail thickness, armature throat thickness and armature head height, with the encore law, contact area and plastic deformation stress as The structural dimensions of the C-type armature for a 400 kA pulse current are determined, providing a direction for the structural optimisation of subsequent large pulse current C-type armatures.

A Fuzzy Controller for PFN Trigger Time Sequence in Electromagnetic Railgun System

For the electromagnetic launch system, how to realize the wide pulse, fast rise, and small fluctuation of pulse forming network output current is a core problem. A trigger time sequence control method based on fuzzy theory for the pulse forming network is proposed in this paper. First, circuit models of pulse forming unit, pulse forming network, and electromagnetic rail launcher is established. Second, a fuzzy trigger time sequence controller model for pulse forming network is designed by using Simulink. Third, fixed time sequence discharge tests consisting of 20 pulsed forming units on the linear simulation load are carried out to verify the accuracy of the simulation model. Finally, discharge tests on the linear simulation load and launch tests on the electromagnetic railgun are carried out to verify the precision of the fuzzy controller output respectively. The results show that the designed fuzzy trigger time sequence controller can obtain the ideal trigger time sequence, which demonstrates the pragmatic and reliability of fuzzy control algorithm.

Research on the Mode for New Quality Air Defense Weapons Integration into Air Defense System

To address the evolving problem of how to applicate the increasingly developed laser, microwave, electromagnetic rail gun and other new quality air defense weapons after they are integrated into the air defense system, this paper summarizes three development states of the new quality air defense weapons system, namely, a small amount of equipment, a large number of equipment and intelligent integration, based on the performance development of new quality air defense weapons. For the first time, the system proposes three combat modes of new quality air defense weapons, namely, “pointed mode”, “layered mode” and “networked mode”, the air raid threat and application of each mode are clarified. This will provide ideas and methods for the operational application of new air quality defense weapons at different stages of development.

Research on Loss and Temperature Rise of Pulse Inductor for Electromagnetic Rail Launch

The copper foil pulse inductor used for electromagnetic rail launch works in instantaneous super-high current conditions, and the copper foil needs to bear high current density, which also affects the eddy current distribution in the metal shell. The loss and temperature rise generated in the copper foil and the shell affect the efficiency and operation stability of the pulse inductor, and are important performance indicators to test whether the pulse inductor can achieve rapid and continuous pulse discharge. The magneto-thermal coupling simulation model was built by the finite element method (FEM) and boundary element method (BEM), and the numerical calculation results of the loss and temperature rise of the copper foil and shell of the pulse inductor were obtained when the electromagnetic rail launched. Aiming at the problem of large shell loss, a structural optimization scheme is proposed to increase the gap between the copper foil and the shell and reduce the wall thickness of the shell. The simulation shows that after the structure is optimized, the copper foil loss slightly increases by 1.29% during a single launch, but the shell loss decreases by 21.33%, at the same time, the temperature rise of copper foil and the strength of the shell meet the safety requirements of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$6\times $ </tex-math></inline-formula> consecutive launches. Finally, the accuracy of the simulation calculation model and the scheme to reduce eddy current loss of shell are verified by experimental measurement.

Delamination failure analysis of G10 insulator in electromagnetic rail launcher

AbstractThe electromagnetic (EM) rail launcher G10 insulator is prone to delamination damage during launch, which affects the service life of the insulator. Through the secondary development of ABAQUS® commercial finite‐element software, an EM‐structure coupling launch dynamics model considering projectile‐barrel coupling is established. The simulation indicates that the transverse swing of the projectile changes in a sine‐like law, and the time of the upper half wave corresponds to the pulse width of the impact force pulse waveform. The stress concentration occurs on the inner surface of the insulator where the contact‐impact occurs, resulting in impact damage. The midline of the insulator inner surface bears a large compressive strain under the action of pre‐tightening force, and the insulator is compressed oscillatingly under the influence of the time‐varying load of the rail during launch. Under the condition of repeated launch, the launch package repeatedly impacts the insulator, and the alternating load of the rail is cyclically loaded on the insulator with impact damage, which will cause the compression fatigue of the insulator and the expansion of impact damage crack. They are the main reasons for the delamination failure of insulator, and the experimental analysis is carried out. This study provides a method to study the delamination failure mechanism of the insulator, and provides guidance for improving the life of the insulator.