Arc discharge simulation method and system under pivot rail contact and complete loss contact

Abstract

The invention discloses an arc discharge simulation method and system under pivot rail contact and complete loss contact, and relates to the technical field of electromagnetic rail launching devices, and the method comprises the steps: constructing a multi-field coupled magnetohydrodynamic simulation model; under the development stages of different pivot rail contact states, the electric heating field coupling distribution condition of a pivot rail contact interface is analyzed; in the coexistence stage of the three contact states, the change rules of pivot rail contact interface parameters and arc discharge parameters under different metal liquefied layer thicknesses and armature empennage roughness are analyzed; and in a complete contact loss state of the pivot rail, obtaining a change rule of an arc form, an arc temperature and an arc energy flux density in a plasma gap along with emission time and a change rule of a pivot rail contact interface parameter and an arc discharge parameter under different numbers of pivot rail micro-contact points, pivot rail gap widths and rail surface roughness. And performing simulation analysis on the multi-physics field coupling distribution characteristics of the contact interface in different pivot rail contact state development stages.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic rail launch devices, and in particular to a method and system for simulating arc discharge under conditions of pintle-rail contact and complete loss of contact. Background Art

[0002] During electromagnetic rail launch, the contact surface between the pintle and rail undergoes physical and chemical changes such as melting, vaporization, and plasma generation, causing degradation of electrical conductivity and mechanical properties. These changes can disrupt the stability of the sliding electrical contact, leading to rail transitions and severe ablation, shortening rail life and reducing launch stability, thus hindering the development of electromagnetic rail launch technology.

[0003] Current research on the mechanism of transition arcing is largely limited to thermal perspectives induced by melting waves or electromagnetic perspectives induced by pulsed currents. However, the relative motion between the armature and rail is a high-current, high-speed sliding electrical contact process, and armature-rail transition occurs under the combined effects of extreme impact electromagnetic, thermal, and mechanical loads. It is necessary to establish a model for arc discharge at the contact interface and investigate the coupled characteristics of electromagnetics, thermodynamics, and fluid kinematics. Furthermore, equivalent simulation methods for the armature-rail contact interface characteristics and transition arcing between the armature and rail are not yet fully established, from the initial launch to transition arcing. Further simulation is needed to determine the specific development stage corresponding to transition arcing and clarify the transition arcing mechanism based on the contact interface characteristics. During this process, changes in the armature-rail contact state affect its multi-field coupling distribution characteristics, necessitating a detailed analysis of the interface electrothermal characteristics and arc discharge parameters.

[0004] Secondly, the accumulation of launches leads to increased rail surface roughness, resulting in a plasma gap between the armature and rail due to insufficient contact, which in turn triggers arcing. This not only affects the armature's motion and launch quality, but also causes severe ablation damage to the armature and rail surface, causing a sharp decline in rail performance, significantly reducing its service life and reuse rate.

[0005] Research has shown that arc generation, which triggers destructive changes in the pintle-rail interface properties, is the primary cause of pintle-rail metal ablation. However, current research on the spatiotemporal evolution of arcing between the pintle and rail, and the resulting metal ablation, is insufficiently studied, failing to consider the changes in key parameters such as arc discharge morphology, energy flux density, and internal temperature during electromagnetic emission. The dynamic development of arc morphology and parameters within the plasma gap, as well as the mechanisms by which factors such as the number of micro-contact points, gap width, and rail surface roughness influence the pintle-rail contact interface properties and arc discharge parameters, remain to be clarified. Summary of the Invention

[0006] To solve the above problems, the present invention proposes a method and system for simulating arc discharge under pivot-rail contact and complete loss of contact, establishes a pivot-rail contact interface model considering damage roughness and a magnetohydrodynamic model of arc discharge development between interfaces, and simulates and analyzes the multi-physical field coupling distribution characteristics of the contact interface under different pivot-rail contact states.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a method for simulating arc discharge under conditions of pivot-rail contact and complete loss of contact, comprising: By synthesizing randomly distributed track roughness surface data, we construct track surface curves at different roughness levels, and then build a geometric model of the transition between the pivot-rail contact interface under different roughness levels. Based on this geometric model, we build a magnetohydrodynamic simulation model of arc discharge between the pivot-rail contact interface that simultaneously considers the multi-field coupling of electric, magnetic, thermal, and fluid fields. Based on a magnetohydrodynamic simulation model, the electrothermal field distribution at the pivot-rail contact interface was analyzed during the pivot-rail dry sliding contact state, the mixed lubrication contact state where the pivot-rail dry sliding coexists with a metal liquefaction layer, and the transitional contact state where the metal liquefaction layer coexists with a plasma gap. The maximum current density, maximum temperature, and respective positions of the pivot-rail contact interface were determined as the contact state phases changed. Furthermore, based on a constructed arc discharge model between the pivot-rail contact interfaces in the three coexisting contact states, the variation patterns of the pivot-rail contact interface parameters and arc discharge parameters were analyzed under different metal liquefaction layer thicknesses and armature tail fin roughnesses. According to the magnetohydrodynamic simulation model, arc ablation simulation was carried out when the pivot rail was completely out of contact. The variation patterns of arc morphology, temperature and energy flux density in the plasma gap with emission time were obtained, as well as the variation patterns of pivot rail contact interface parameters and arc discharge parameters under different numbers of pivot rail micro-contact points, pivot rail gap widths and rail surface roughness.

[0008] In a second aspect, the present invention provides an arc discharge simulation system under pivot-rail contact and complete loss of contact, comprising: a model construction module configured to construct track surface curves at different roughness levels by synthesizing randomly distributed track roughness surface data, thereby constructing a geometric model of the transition between the pivot-rail contact interface at different roughness levels, and based on the geometric model, constructing a magnetohydrodynamic simulation model of arc discharge between the pivot-rail contact interface that simultaneously considers multi-field coupling of electric field, magnetic field, thermal field, and fluid field; The simulation module for the pivot-rail contact state is configured to analyze the electrothermal field distribution at the pivot-rail contact interface in the pivot-rail dry sliding contact state, the mixed lubrication contact state in which the pivot-rail dry sliding coexists with a metal liquefaction layer, and the transitional contact state in which the metal liquefaction layer coexists with a plasma gap, based on a magnetohydrodynamic simulation model. This module determines how the maximum current density and temperature of the pivot-rail contact interface, as well as their respective positions within the pivot-rail contact interface, change with the contact state stages. Furthermore, based on a constructed arc discharge model between the pivot-rail contact interfaces in which the three contact states coexist, the module analyzes how the pivot-rail contact interface parameters and arc discharge parameters change under different metal liquefaction layer thicknesses and armature tail fin roughnesses. The complete loss of contact simulation module is configured to perform arc ablation simulation when the pivot rail is completely out of contact based on the magnetohydrodynamic simulation model, and obtain the change law of arc morphology, temperature and energy flux density in the plasma gap with the emission time, as well as the change law of pivot rail contact interface parameters and arc discharge parameters under different pivot rail micro-contact points, pivot rail gap width and rail surface roughness.

[0009] In a third aspect, the present invention provides an electronic device comprising a memory and a processor, and computer instructions stored in the memory and executed on the processor, wherein the computer instructions, when executed by the processor, perform the method described in the first aspect.

[0010] In a fourth aspect, the present invention provides a computer-readable storage medium for storing computer instructions, wherein when the computer instructions are executed by a processor, the method described in the first aspect is performed.

[0011] In a fifth aspect, the present invention provides a computer program product, comprising a computer program, which implements the method described in the first aspect when executed by a processor.

[0012] Compared with the prior art, the present invention has the following beneficial effects: The results of rail surface damage from electromagnetic rail launch experiments indicate that increasing launch times and usage frequency will result in the rail frequently experiencing various types of cumulative ablation damage. Among these, transition ablation, accompanied by arcing, is the most destructive type of arc erosion, causing significant physical changes in the pivot-rail contact state. The generation of arc discharges at the pivot-rail contact interface is closely related to the contact interface characteristics at each pivot-rail contact state development stage. However, currently, there is a lack of suitable experimental instruments and methods for effective on-site testing of the arc generation principle and the development patterns of transition ablation at the pivot-rail contact interface. Furthermore, equivalent simulations of pivot-rail contact interface characteristics and transition arcing between the pivot and rails are also incomplete. To simulate and invert the damage patterns, the present invention establishes a pivot-rail contact interface model that considers damage roughness and a magnetohydrodynamic model of arc discharge development between the interfaces. The multi-physics coupling distribution characteristics of the contact interface at different pivot-rail contact state development stages are analyzed to explore the generation mechanism and dynamic development and evolution characteristics of arc initiation discharges when the pivot-rail contact interface develops to the transition contact state. When considering the actual situation where multiple pivot-rail contact states exist simultaneously, the influence of two pivot-rail contact conditions, namely the thickness of the metal liquefaction layer and the surface roughness of the armature tail, on the contact interface and transition arcing discharge parameters are studied.

[0013] The proposed method targets situations where arc discharge between the armature and rails is strongest and arc erosion is most severe. This occurs when contact between the armature and rails is completely lost, the metal liquefaction layer is completely depleted, and conduction is maintained only by the plasma gap, leading to transitional erosion into the most destructive arc erosion. Based on a magnetohydrodynamic model, the proposed method uses the inner contact surface of the rails as the arc discharge anode and the armature contact surface as the cathode to investigate the dynamic development of arc morphology and parameters in the plasma gap over time. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Flowchart of the arc discharge simulation method under pivot-rail contact and complete loss of contact provided in Example 1 of the present invention; Figure 2 Schematic diagram of a magnetohydrodynamic simulation model of arc discharge between the pivot and rail contact interfaces provided in Example 1 of the present invention; Figure 3 A graph showing the changing trends of the pulse current, dry friction heat power, and maximum temperature of the hinge-rail contact interface during the launch process provided in Example 1 of the present invention; Figure 4 A spatial distribution diagram of the current density at the contact interface of the pivot rail in the state of sliding contact of the pivot rail provided in Example 1 of the present invention; Figure 5 A time distribution diagram of the current density at the contact interface of the pivot rail in the state of sliding contact of the pivot rail provided in Example 1 of the present invention; Figure 6A temperature spatial distribution diagram of the pivot-rail contact interface in the pivot-rail dry sliding contact state provided in Example 1 of the present invention; Figure 7 A temperature-time distribution diagram of the pivot-rail contact interface in the pivot-rail dry sliding contact state provided in Example 1 of the present invention; Figure 8 The maximum temperature, maximum current density, and maximum energy flux density of the electromagnetic rail launch device provided in Example 1 of the present invention vary with the gap length; Figure 9 Schematic diagram of the pivot-rail contact interface model in which three contact states coexist, as provided in Example 1 of the present invention; Figure 10 A diagram showing changes in arc energy flux density with increasing abscissa at different metal liquefaction layer thicknesses provided in Example 1 of the present invention; Figure 11 A diagram showing changes in arc energy flux density with increasing vertical coordinates at different metal liquefaction layer thicknesses provided in Example 1 of the present invention; Figure 12 A graph showing changes in armature-rail contact interface parameters and arc discharge parameters under different armature tail fin roughnesses provided in Example 1 of the present invention; Figure 13 A diagram showing the dynamic development of arc discharge temperature in the gap at a 0.5 ms emission time provided in Example 1 of the present invention; Figure 14 A diagram showing the dynamic development of arc discharge temperature in the gap at a 1.5 ms emission time provided in Example 1 of the present invention; Figure 15 A diagram showing the dynamic development of arc discharge temperature in the gap at a 2.5 ms emission time provided in Example 1 of the present invention; Figure 16 A diagram showing the dynamic development of arc discharge temperature in the gap at a 3.5 ms emission time provided in Example 1 of the present invention; Figure 17 A diagram showing the dynamic development of arc energy flux density within the gap at the 0.5 ms emission time provided in Example 1 of the present invention; Figure 18 A diagram showing the dynamic development of arc energy flux density within the gap at a 1.5 ms emission time provided in Example 1 of the present invention; Figure 19 A diagram showing the dynamic development of arc energy flux density within the gap at a 2.5 ms emission time provided in Example 1 of the present invention; Figure 20 This is a diagram showing the dynamic development of arc energy flux density in the gap at the 3.5ms emission moment provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0015] Example 1 This embodiment provides a method for simulating arc discharge under conditions of pivot-rail contact and complete loss of contact. Figure 1 As shown, including: By synthesizing randomly distributed track roughness surface data, we construct track surface curves at different roughness levels, and then build a geometric model of the transition between the pivot-rail contact interface under different roughness levels. Based on this geometric model, we build a magnetohydrodynamic simulation model of arc discharge between the pivot-rail contact interface that simultaneously considers the multi-field coupling of electric, magnetic, thermal, and fluid fields. Based on a magnetohydrodynamic simulation model, the electrothermal field distribution at the pivot-rail contact interface was analyzed during the pivot-rail dry sliding contact state, the mixed lubrication contact state where the pivot-rail dry sliding coexists with a metal liquefaction layer, and the transitional contact state where the metal liquefaction layer coexists with a plasma gap. The maximum current density, maximum temperature, and respective positions of the pivot-rail contact interface were determined as the contact state phases changed. Furthermore, based on a constructed arc discharge model between the pivot-rail contact interfaces in the three coexisting contact states, the variation patterns of the pivot-rail contact interface parameters and arc discharge parameters were analyzed under different metal liquefaction layer thicknesses and armature tail fin roughnesses. According to the magnetohydrodynamic simulation model, arc ablation simulation was carried out when the pivot rail was completely out of contact. The variation patterns of arc morphology, temperature and energy flux density in the plasma gap with emission time were obtained, as well as the variation patterns of pivot rail contact interface parameters and arc discharge parameters under different numbers of pivot rail micro-contact points, pivot rail gap widths and rail surface roughness.

[0016] The following first explains the construction of a geometric model when the transition occurs at the pivot-rail contact interface under different roughness.

[0017] After multiple electromagnetic rail launch experiments, under extreme conditions such as frequent high-energy pulse current flow and high-speed armature friction, various irreversible damages will appear on the rail surface, such as groove ablation, gouging ablation, transition ablation and arc ablation, which seriously affect the service life, launch quality and efficiency of the launch device. Among them, arc ablation causes the most severe damage to the rail, but transition ablation is the main cause of arc ablation. Transition refers to damage to the armature and rail surface, which makes the armature-rail contact loose and a gap is formed locally, which in turn generates a high-temperature and high-energy plasma arc, exacerbating arc ablation and causing material melting, spattering, viscosity and even sublimation. Since this process is difficult to directly observe through experimental means, it is necessary to establish an arc discharge plasma model at the armature-rail contact interface to conduct research at the numerical simulation level.

[0018] During the electromagnetic rail launch process, since the metal surface is rough at a microscopic scale, the actual contact between the rails occurs only at a few raised micro-contact points. When the current flows through these discrete micro-contact points, the path is contracted and the current flows from the micro-contact points to the next conductor. Surface roughness can be used to measure the degree of damage and geometric micro-morphology of the rail surface. Common roughness indicators include average roughness. Ra , maximum height Rz and root mean square roughness R .

[0019] (1); (2); (3); in, Ra is the average value of the absolute value of the contour deviation from the baseline, L is the total length of the measured track, y ( x ) is the offset value of the track surface profile; Rz Refers to the maximum height difference between the peak and valley values ​​within the measurement interval; R It is the root mean square value of the deviation between each point on the contour line and the average line; x is the horizontal coordinate value of the track surface contour.

[0020] When constructing the geometric model of the rough surface, based on the spatial frequency and element wave theory, the sum of the trigonometric functions expanded by the Fourier series is used to synthesize the real rough surface data with completely random distribution, and the one-dimensional curve of the rough surface for: (4); Where, φ ( υ ) is the phase angle, ± V is the spatial frequency υ The maximum and minimum cutoff values ​​of P is the proportional coefficient of the amplitude; For each spatial frequency υ The amplitude corresponding to the elementary wave; g ( υ ) is a random function with Gaussian distribution; a ( υ ) is the amplitude of each element wave Multiply by a random function with a Gaussian distribution g ( υ ) generated amplitude; w ( υ ) is a uniform random function, and the phase angle is from the uniform random function w ( υ ) to sample between –π / 2 andπ / 2 is in accordance with the uniform random distribution, φ ( υ )= w ( υ ); is the spectral index, which indicates the decay rate of the higher frequency element wave amplitude.

[0021] The calculation can be completed and the corresponding roughness curve can be generated by programming the built-in function of the finite element simulation software. Based on formula (4), the variable V and β are taken as 20 and 1 respectively, by changing the proportional coefficient P The track surface curves with different roughness are obtained, and then the geometric model of the transition of the pivot-rail contact interface under different track damage roughness is constructed. The average roughness of different track surface roughness is calculated by formula (1)-formula (3) Ra , maximum height Rz and root mean square roughness R , it is found that as the amplitude proportional coefficient P As the friction increases, the track surface roughness also increases accordingly.

[0022] The following describes the construction of a magnetohydrodynamic simulation model of arc discharge between the pivot and rail contact interfaces.

[0023] First, electromagnetic thermal multi-field coupling is introduced into the equivalent circuit model of the electromagnetic rail launch device to obtain the electromagnetic thermal multi-field coupling model of the entire electromagnetic rail launch process. Then, the magnetohydrodynamics (MHD) equivalent equation of plasma discharge is introduced. The upper half of a section symmetrical about the midline of the launch direction, which is composed of the rail, armature, its contact interface, and the air domain in the chamber, is intercepted. A two-dimensional symmetrical magnetohydrodynamic simulation model perpendicular to the xy plane is established, as shown in the following figure. Figure 2 As shown. It is mainly composed of copper rails, aluminum armatures and air domains, with a length of 40mm. The contact interface between the armature and rails is not tightly fitted, leaving an air gap of about 0.25mm to simulate the arc discharge space when the armature and rails transition due to poor contact. The contact surface roughness of the inner side of the copper rail is set to Ra =541.2μm, indicating surface damage to the rail caused by multiple electromagnetic launches. The magnetohydrodynamic simulation model of arc discharge at the contact interface of the rail and pivot involves multi-field coupling of electric, magnetic, thermal, and fluid fields. At the electromagnetic field level, since the electromagnetic rail launcher model is converted from three-dimensional space to a two-dimensional xy plane, the pulse current terminal boundary condition value should also be divided by the rail height of 23mm, resulting in a value of 1 / 23 of the original pulse current.

[0024] At the thermal field level, the boundary conditions between the copper track and the air domain and the outside world are all in the form of convective heat flux. According to the inherent properties of the materials, the heat transfer coefficient is h Set to 400W / (m 2 ·K) and 15W / (m 2 ·K); the connection module between the aluminum armature and the outside world is still the other half of it, so the boundary condition of its heat flux is inward heat flux, and its value is about 237W / m 2 Set the air domain to fluid heat transfer, and the copper rails and aluminum armature to solid heat transfer.

[0025] At the fluid field level, if the armature is considered relatively stationary during firing, the air within the barrel continuously accelerates from the front to the rear of the armature at a relative velocity, forming a laminar flow. In this model, the normal inflow velocity of the air in front of the armature is approximately equal to the actual firing velocity of the armature. Based on the Navier-Stokes equations (NS equations) and the continuity equation, the equation for air fluid motion is: (5); (6); Where, ρ is the density of the fluid or solid in kg / m 3 ; p is the fluid pressure, η is the fluid dynamic viscosity; u is the fluid velocity, in m / s; is the vector differential operator; T is the temperature; I is the current. The Navier-Stokes equation (5) represents the conservation of momentum, and the continuity equation (6) represents the conservation of mass.

[0026] Finally, after coupling the electromagnetic, thermal, and fluidic four-fields, a magnetohydrodynamic multi-physics coupling model of arc discharge in an air gap was constructed to simulate the interaction between the magnetic field and the conductive fluid. This was achieved by coupling the magnetic field interface with the laminar flow interface. The core bidirectional coupling mechanism is: (7); (8); Where, J is the current density, B is the magnetic flux density, F is the Lorentz force, E is the induced electromotive force. Equation (7) expresses the Lorentz force F Coupling transfer from the magnetic field level to the laminar level; Equation (8) represents the coupling transfer of the electromotive force (induced electric field) from the laminar level to the magnetic field level.

[0027] For the coupling of electromagnetic field and thermal field, the contact surface of the track is set as the anode of the balanced discharge boundary heat source, and the contact surface of the armature is set as the cathode. The total heat source composed of the multi-physics field coupling of the balanced discharge heat source Q for: (9); Q Including Joule heating of resistors Q ohm , volume net radiation loss Q rad and electron transport enthalpy Q enthalpy .in, Q ohm 、 Q enthalpy The equations are: (10); (11); Where, k B is the Boltzmann constant, T is the temperature, q is the charge; k is the thermal conductivity of the fluid, in W / (m·k); C p It is the heat capacity of a fluid or solid at constant pressure, measured in J / (kg·K).

[0028] The following describes the multi-field coupling distribution characteristics of the contact interface during the development stage of the pivot-rail contact state.

[0029] 1. Sliding contact state of pivot rail.

[0030] At the beginning of electromagnetic launch, the amplitude of the pulse current in the circuit is very small, the armature speed in the barrel is very low, and the temperature of the pintle-rail interface is far from the melting point of the aluminum armature. At this time, the pintle-rail contact interface is completely in a dry sliding contact state. The heat source of the pintle-rail contact interface mainly includes two components: the Joule heating effect of the contact resistance and the heat generated by dry friction.

[0031] Among them, the Joule heat power generated by the contact resistance is P J for: ; i is the pulse current flowing through the contact resistance, R c is the contact resistance. Contact resistance Joule heat power P J The size mainly depends on the pulse current and contact resistance. Since the electromagnetic launch device is always in an ideal close contact state without transition when the pivot rail is in dry contact, the contact points between the pivot rails are dense and the contact area is small.A c is very large, so the contact resistance R c The value is very small, on the order of nano-ohms.

[0032] Dry friction heat power of another heat source at the pivot-rail contact interface P f1 : ;Dry sliding friction coefficient due to solid-solid friction μ 1 is larger, so the value is 0.2. Dry friction heat power P f1 Inductance gradients in the rail and armature materials Under the premise of keeping the same, with the pulse current i Square, initial preload F n0 Positively correlated with the armature speed v There is a positive proportional relationship.

[0033] Due to contact resistance R c The value is extremely small, the contact resistance Joule heat power P J The value is much smaller than the dry friction heat power P f1 ,Right now P J ≪ P f1 Therefore, when the pivot rail interface is in a dry sliding contact state of solid-solid close contact, the dry friction heat power is the main heat source of the pivot rail interface and the most important factor causing its temperature rise. i , dry friction heat power P f1 And the maximum temperature of the pivot rail contact interface T c The relationship and change law between the three are studied. According to the electromagnetic orbit launch field-path coupling model, six moments are selected: 0.5ms, 1.13ms, 2ms, 4ms, 6ms, and 8ms when the pulse current reaches its peak value, to explore their changing trends with the launch time, such as Figure 3 As shown in the figure, the electromagnetic rail launch field-circuit coupling model is obtained by performing launch simulation on the equivalent circuit model to obtain the armature rail loop pulse current, armature mechanical parameters and armature kinematic parameters, and then importing them into the electromagnetic thermal multi-physics field coupling model to obtain the field-circuit coupling model of the electromagnetic rail launch device.

[0034] like Figure 3It can be seen that the amplitude of the pulse current has been on an upward trend since 0.5ms, reaching a peak of 67148A at 1.13ms, and then began to decay and decrease with the release of the pulse capacitor energy; the dry friction heat power and the maximum temperature of the pivot-rail contact interface have exactly the same change trends with the emission time, both of which continue to increase from 0.5ms to 2ms, and reach their maximum value at 2ms. At this time, the maximum value of the dry friction heat power is 8194.2W and the maximum temperature of the pivot-rail interface is 57.2℃, and then from 2ms onwards, they continue to decrease with the rapid decay of the pulse current.

[0035] In summary, pulse current i The peak moment is not the same as the dry friction heat power P f1 Maximum temperature of the contact interface with the pivot rail T c Synchronous, P f1 and T c The time of reaching the maximum value should be delayed by i This is because the dry friction heat power P f1 The size of the pulse current is not only related to i It is related to the square of the pulse current and is directly proportional to the armature speed. i When the peak value is reached at 1.13ms, the armature speed is only 31.73m / s. At 2ms, although the pulse current amplitude drops slightly to 52898A, the armature launch speed increases to 71.57m / s. Therefore, it can be concluded that the dry friction heat power at 2ms is the maximum. At the same time, since the maximum temperature rise of the armature-rail interface mainly depends on the dry friction heat power, T c The maximum value is also generated at the moment of the emission process P f1 The maximum value corresponds to 2ms.

[0036] In order to analyze the multi-field coupling distribution characteristics of the electromagnetic rail launcher in the state of dry sliding contact between the armature and rail under the influence of the roughness of the rail surface damage, an electrothermal field coupling model of the armature-rail interface and the air domain in the barrel in the two-dimensional plane was obtained based on the improved finite element model of the three-dimensional electromagnetic rail launcher. Due to the limitations of the simulation software itself, there are differences between the simulation results of the two-dimensional model and the simulation results of the three-dimensional model. The two-dimensional model is used as the standard in this embodiment. By analyzing the distribution of current density and temperature in the state of dry sliding contact between the armature and rail at the moment of maximum dry friction heat power of 2ms, it can be seen that the current density in the track is mainly concentrated in the partial section before the pulse current flows into the armature through the track, and the current density distribution is uniform, about 4.6×10 5 A / m2 ; In the track section before the armature head along the launch direction, the current density that does not form a current path with the armature and the opposite track is 0. The current density concentration areas in the armature are mainly in two parts: the armature groove and the front and rear ends of the armature-rail contact side, and these two parts are the positions with the highest current density in the entire launch device at that moment; at the armature-rail interface, affected by the current skin effect and velocity skin effect, the current density is more concentrated in the high curvature bends at the front and rear ends of the armature-rail interface, that is, part of the current first enters from the rear corner of the armature tail, and the remaining current all flows into the armature through the head corner of the armature side. Therefore, these two corner ends are the parts where the current density and Joule heat are most concentrated. As for the temperature distribution at the 2ms moment, under the combined effects of Joule heat and friction heat, the high-temperature area of ​​the track is mainly located in a section about 40mm behind the interface between the armature and track. The track temperature shows a decreasing trend from the highest temperature point to both sides of the track. The highest temperature point is at the rear corner of the armature tail, reaching 57.2°C; the armature high-temperature area is also concentrated at the rear of the armature tail, gradually decreasing from near the corner end to the armature head; the high-temperature area in the air domain is close to the high-temperature area surface of the track and armature, and quickly decreases to the surrounding low-temperature air.

[0037] While the above analysis reflects the current density and temperature distribution of the entire device under dry sliding contact between the armature and rail, the temporal and spatial characteristics of the coupled electrothermal field distribution at the armature-rail contact interface require further analysis. Therefore, with the corner at the end of the armature tail as the coordinate origin and the launch direction as the positive axis, the temporal characteristics of the current density and temperature at the armature-rail contact interface were investigated.

[0038] Figure 4-Figure 5 The figures are the spatial distribution diagram and the temporal distribution diagram of the current density at the pivot-rail contact interface under the state of dry sliding contact between the pivot and rail, respectively; at the emission moments corresponding to different pulse current amplitudes, the contact interface with a length of 28 mm presents a "two high sections and a low middle section" distribution. Among them, the current density at the front end (28 mm) of the pivot-rail contact interface is greater than the end end (0 mm) of the interface, which is the highest current density of the entire pivot-rail interface. At the same moment, the current density drops rapidly from the end end to about 2 mm from the end end, then gradually levels off, and then starts to rise sharply from about 26 mm from the end end of the interface, and finally reaches the maximum value at the front end of the pivot-rail interface. As the emission process progresses, the current density at the pivot-rail interface rises rapidly with the increase of the pulse current (from 0 ms to 1.13 ms), reaches the maximum value at 1.13 ms, and then shows a gradually decreasing trend as the current decays from 2 ms.

[0039] Figure 6-Figure 7The figures are the spatial and temporal distribution of the temperature of the pivot-rail contact interface in the state of dry sliding contact between the pivot and rail, respectively. During the launch process, the highest temperature point of the pivot-rail contact interface at each moment along the positive direction of the contact interface is located between 2.5mm and 4.7mm from the end of the contact interface, showing a spatial characteristic of "local increase followed by overall decrease". The pivot-rail contact interface temperature rises to 57.2°C with the launch time, with the peak corresponding to 2ms, while the non-pulse current peak corresponds to 1.13ms, and then the temperature gradually decreases, which is consistent with the Figure 3 The law revealed. During the heating stage (0.5ms, 1.13ms, 2ms), the position of the highest temperature point continuously moves forward along the positive direction of the pivot-rail contact interface as the temperature rises. At 2ms, the highest temperature point is located approximately 4.7mm from the end of the contact interface, closer to the front end of the contact interface. During the cooling stage (4ms, 6ms, 8ms), the position of the highest temperature point gradually moves back. Therefore, in the dry sliding contact state, the higher the temperature of the pivot-rail contact interface, the closer its temperature peak point is to the front end, and the more concentrated the high-temperature area is at the end of the interface.

[0040] 2. Mixed lubrication contact state where the pivot rail slides dry and the metal liquefaction layer coexists.

[0041] During the electromagnetic rail launch process, when the temperature of the armature-rail contact interface exceeds the melting point of the aluminum alloy armature, the solid aluminum on the armature contact surface melts into liquid aluminum, forming a metal liquefaction layer (LMF). The contact state will gradually transition from the initial dry sliding to the full coverage stage of the metal liquefaction layer, and the physical form of the armature-rail contact will also change from "solid-solid" to "solid-liquid-solid". However, in the dry sliding contact model, the maximum contact interface temperature is only 57.2°C, which is much lower than the melting point of the armature material aluminum alloy 6061, which is 582°C. Therefore, the metal liquefaction layer cannot be formed and it is always in a dry sliding state. The main reason is that the pulse current i The value is small, resulting in dry friction heat power P f1 Therefore, in order to achieve a higher temperature rise, it is necessary to increase the pulse current value, that is, to increase the charging voltage of the pulse capacitor module in the equivalent circuit model jointly programmed with the field model. By increasing the charging voltage value of the pulse capacitor in the equivalent circuit model from 7kV to 13.5kV, the simulation shows that the pulse current amplitude at 2ms exceeds 100kA and increases to 102.024kA, and the driving force on the armature is reduced. F e Increased to 2094.86N, the armature movement speed v AWhen the updated parameters were re-imported into the multi-field coupling model, the temperature at the pivot-rail contact interface reached a maximum of 681°C, exceeding the melting point of the armature aluminum alloy 6061. The pivot-rail interface entered a mixed lubrication contact phase where dry sliding and a metal liquefaction layer coexisted.

[0042] To describe the sliding friction coefficient of the pivot-rail contact interface μ The Stribeck lubrication curve is drawn based on the relationship between the development and change of the contact state. The dimensionless lubrication parameter ( ηv / p , that is, lubricating viscosity η , movement speed v and normal load p ) is the horizontal axis, reflecting the transition process between different lubrication states. It can be seen that during the initial operation of the armature, the pivot-rail contact state is dry sliding. With low pulse current and low armature speed, the temperature rise at the pivot-rail interface is limited, resulting in a solid-solid contact boundary lubrication regime with a high sliding friction coefficient of approximately 0.2. As the armature speed increases and the pulse current rises, the pivot-rail contact interface begins to generate significant heat, exceeding the armature melting point. This causes the solid aluminum surface of the armature to continuously melt, and liquid aluminum forms and expands. The lubrication between the pivot and rail enters a mixed lubrication regime where both solid-solid and solid-liquid-solid lubrication coexist, and the friction coefficient gradually decreases due to lubrication. Ultimately, under the continued high temperature generated by frictional heat, a liquefied metal layer covers the entire pivot-rail contact interface, and the pivot-rail lubrication state enters the fluid lubrication regime, with the friction coefficient finally stabilizing at approximately 0.04. Therefore, during the launch process, the current-carrying sliding friction coefficient between the pivot and rail continuously decreases from the dry sliding friction stage, ultimately stabilizing at a saturated minimum value.

[0043] Sliding friction coefficient revealed by Stribeck lubrication curve μ The friction coefficient between the metal liquefied layer of the armature and the copper track is μ 2 value is set to 0.04, the friction heat source of the metal liquefaction layer P f2 The dry friction heat of solid-solid contact is also converted into viscous friction heat of fluid. In order to simplify the analysis of the lubrication behavior of the metal liquefaction layer formed at the armature-rail contact interface under multi-field coupling and sliding friction conditions in the model, it is assumed that the thickness of the metal liquefaction layer remains unchanged at 20μm during the entire launch process, and only lateral expansion occurs in the x-axis of the launch direction, and there is no slip on the armature surface, and it moves forward at the same speed as the armature as a whole. Under this assumption, the Reynolds equation representing the hydrodynamic lubrication behavior of the metal liquefaction layer between relatively moving surfaces is introduced into the model, as shown in Equation 2. Where, h is the thickness of the liquid film, p is the pressure inside the liquid film, ηis the dynamic viscosity of the metal liquid, v r is the velocity vector of the relative motion surface, t The temperature distribution at the armature-rail contact interface during dry sliding contact indicates that the highest armature temperature during launch is located at the rear of the armature tail, with the temperature gradually decreasing from the tail corner toward the armature head. Therefore, the metal liquefaction layer first forms at the rear of the armature tail and gradually expands toward the armature head as launch progresses, eventually covering the entire contact interface.

[0044] In order to explore the distribution law of the electrothermal coupling field of the armature-rail contact interface caused by the metal liquefaction layer extending toward the armature head in the mixed lubrication contact state, the development length of the metal liquefaction layer was set to L LMF The contact lengths of 3.5 mm, 7 mm, 10.5 mm, 14 mm, 17.5 mm, 21 mm, 24.5 mm, and 28 mm were selected, and the spatial distribution characteristics of the current density and temperature at the pivot-rail contact interface at different lengths at 0.2 ms were analyzed. It can be seen that in the mixed lubrication contact state, although the length of the metal liquefaction layer varies greatly, the overall distribution trend of the current density at the pivot-rail contact interface is basically the same. Due to the velocity skin effect, the current density reaches its maximum peak of 1.8 × 10 6 A / m 2 , and then dropped rapidly within a range of 2 mm, then stabilized, and finally rebounded slightly near the front end of the contact interface. 6 S / m is much lower than that of solid aluminum (3.03×10 7 S / m), which makes the current more inclined to flow into the contact interface in the dry sliding contact state with high conductivity. Therefore, the current density in the dry sliding contact area is higher than that in the metal liquefaction layer area.

[0045] However, in the overall distribution above, when the current density is at the junction of the metal liquefaction layer and the dry sliding, the current density will jump, and will concentrate into the armature at the critical point when it is about to leave the solid-liquid-solid contact form containing the metal liquefaction layer and enter the solid-solid contact form. L LMF From 3.5mm to 14mm, the current density increased from 664173A / m 2 Gradually reduced to 502128 A / m 2 Since the existence of the metal liquefaction layer will change the current density distribution at the pivot-rail contact interface, L LMF As the thickness gradually increases to 14 mm, the current flowing into the metal liquefaction layer increases, while the current flowing into the dry sliding contact interface decreases, indicating that the current gradually tends to be balanced between the two regions;L LMF When it continues to grow to 24.5mm, the current density rises to a maximum of 713549 A / m 2 This is because L LMF As the process continues, the lubrication zone of the low-conductivity metal liquefaction layer continues to expand while the dry sliding zone of high conductivity continues to compress. The current is forced to flow into the shorter contact interface in the dry sliding zone, which increases the current density at the junction of the two contact states. L LMF = 28mm, the contact interface is completely covered by the liquefied metal layer, causing an overall decrease in conductivity. Combined with the current skin effect and tip effect, the current density is concentrated at the ends of the pivot-rail contact interface, while the distribution of the liquefied metal layer in the middle becomes more sparse. In short, the continuously advancing liquefied metal layer significantly changes the distribution of current density at the pivot-rail contact interface due to its reduced conductivity.

[0046] As the LMF development length increases from 3.5mm to 24.5mm, the temperature distribution pattern of the contact interface is affected by the development of the metal liquefaction layer, and the position of the highest temperature point continues to move toward the front end of the contact interface as the LMF development length increases. Compared with the dry sliding contact state where the highest temperature occurs at the corner at the end of the armature tail wing, in the mixed lubrication state, its highest temperature occurs in front of the junction between the LMF lubrication area and the dry sliding area, and is always located in the dry sliding contact area. Regardless of the LMF development length, its maximum temperature is higher than the 681°C in the dry sliding contact state. In terms of temperature distribution, in the mixed lubrication contact state, the temperature rises slowly from the end of the contact interface, and there is a significant jump at the junction of the two contact states, and rises to the highest with a larger slope, and then rapidly decreases from the highest temperature point to the front end of the contact interface. This is because the thermal conductivity of liquid aluminum (90W / (m·K)) is lower than that of solid aluminum (201W / (m·K)), causing heat to accumulate in the LMF and difficult to diffuse. The temperature at the contact interface in the lubricated contact state gradually increases. However, when transitioning to the dry sliding contact state, the higher thermal conductivity of solid aluminum and solid copper makes heat easily diffuse, resulting in a rapid decrease in temperature along the x-axis of the emission direction. As the LMF development length increases from 3.5mm to 24.5mm, the temperature at the junction of the lubricated contact state and the dry sliding contact state of the metal liquefaction layer shows a pattern of first decreasing and then increasing: L LMF When the thickness increases to 17.5 mm, the temperature at the joint decreases, and the temperature at the contact interface tends to be uniform. L LMFAfter further increasing to 24.5mm, the temperature at the front end of the contact interface began to rise. This shows that the development of LMF will change the distribution characteristics of the temperature at the pivot-rail contact interface, pushing the highest temperature point forward, thereby intensifying the melting of the aluminum alloy on the armature surface under the dry sliding contact state and promoting further expansion of LMF. As the length of the LMF with low thermal conductivity continues to grow, the length of the dry sliding contact interface with high thermal conductivity continues to shorten, resulting in the high-temperature area being easily concentrated at the front end of the pivot-rail contact interface, and the temperature increase trend is more obvious. When L LMF =28mm, the contact stage of complete fluid lubrication is achieved, the contact interface temperature drops sharply, and the maximum temperature drops from L LMF =24.5mm, the temperature dropped from approximately 760°C to approximately 180°C. This is because the constant-pressure heat capacity of liquid aluminum increased from 900 J / (kg·K) to 1176.73 J / (kg·K), a 30% increase. This enhanced the LMF's temperature inertia and reduced the rate of temperature rise. In short, with the development of the LMF, its lower thermal conductivity and higher constant-pressure heat capacity significantly altered the temperature distribution at the pivot-rail contact interface.

[0047] 3. The transitional contact state where the metal liquefaction layer and the plasma gap coexist.

[0048] When the armature-rail interface is in a fully fluid-lubricated contact state, the armature continues to accelerate within the barrel. Due to inertia, the molten metal layer adhering to the distal end of the armature fin lags behind the armature, causing it to splash behind the armature's direction of motion. Simultaneously, the viscous forces between the liquid aluminum and the solid copper rail cause some of the molten metal layer to remain on the rail surface, resulting in continuous loss of the molten metal layer. As the molten metal layer gradually decreases, a localized gap develops at the interface, extending from the armature fin toward the front end of the contact interface. Ultimately, due to the lack of tight contact between the armature and rail, a transition phenomenon occurs.

[0049] When transition occurs, the discharge gas in the gap quickly fills the gap in the contact interface. Due to the extremely low electrical conductivity of the gas, the contact resistance increases sharply, forming an anode and a cathode at the upper and lower interfaces of the pintle rail. The induced electromotive force between the two electrodes rises sharply, forming an arc discharge in the gap, transforming the contact interface into a "solid-plasma-solid" contact structure. The high energy and extremely high temperature associated with the plasma arc discharge cause severe transitional ablation damage to the pintle rail contact interface.

[0050] When the pivot-rail contact interface is in a transitional contact state where a metal liquefaction layer and a plasma gap coexist, in order to explore the effect of the plasma gap length on the multi-physics field coupling distribution of the contact interface, based on the magnetohydrodynamic equivalent equation of plasma discharge, different gap lengths at 2ms are established in the finite element simulation software. L plm (L plm =4mm, 8mm, 12mm, 16mm, 20mm, 24mm) electromagnetic, thermal and fluid field coupling model. In the model, the average roughness of the armature contact surface in the plasma gap is Ra The thickness of each was set at 62 μm to simulate the surface condition after the loss of the metal liquefaction layer. A 20 μm thick metal liquefaction layer was interspersed in the non-transition region. A preliminary analysis of the temperature, current density, and energy flux density distribution across the entire pivot-rail contact interface was then conducted.

[0051] by L plm =20mm. Analysis of the temperature, current density, and energy flux density distribution in the plasma gap at the armature-rail contact interface at 2ms reveals that the highest armature temperature is concentrated at the transition point between the transition gap and the lubricated contact state with the liquefied metal layer. The temperature gradually decreases from this location toward the surrounding area, with the cooling rate toward the armature head being greater than that toward the armature tail. The rail's high temperature region is concentrated in the contact with the armature's liquefied metal layer. At the lubricated contact interface with the liquefied metal layer, the temperature decreases from its highest value at the end of the LMF to its front end. Meanwhile, the high temperature generated by the arc discharge at the plasma gap contact interface gradually decreases from the front end of the gap toward the inflection point at the end of the armature tail. This indicates that the highest temperature at the armature-rail contact interface is located at the junction of the transition gap and the LMF, and the temperature decreases continuously in the forward and backward directions. The current density distribution is affected by the high resistivity of the gas gap, preventing the pulse current from flowing smoothly and concentrating it at the end of the liquefied metal layer, with its maximum value occurring at the transition point between the transition gap and the liquefied metal layer. The energy flux density distribution is mainly concentrated at the peak height of the rough surface of the armature tail at the end of the gap and the peak height of the rough surface where the distance between the armature and rail contact interface is narrow.

[0052] To study the gap length L plm The impact on the multi-physics coupling distribution of the pivot-rail contact interface, Figure 8 The variation of the maximum temperature, current density and arc discharge energy flux density of the armature, rail, metal liquefaction layer and plasma gap at 2ms is shown. L plm becomes longer and the metal liquefaction layer shortens, resulting in a gradual decrease in the maximum temperature of the four regions. L plm =4mm, about 780℃, down to L plm= 24mm is about 730℃. This is because the metal liquefaction layer is the main heat source at the contact interface of the armature and rail. Its reduction reduces the friction heat generated, thereby reducing the related temperature rise in the armature, rail, LMF and plasma gap. The highest temperature values ​​of the four are LMF, armature, rail, and plasma gap, respectively, but the temperature difference between them is not large, only within 5℃, indicating that the high temperature generated by LMF as the main heat source diffuses to the surrounding through heat conduction and heat convection. The maximum current density will increase with the gap length. L plm As the gap length increases, the current density increases. Due to the extremely low conductivity of the air gap, the current density flows almost entirely from the metal liquefaction layer into the armature. As the metal liquefaction layer continues to shrink, the current density flows more concentratedly through this area, causing its maximum value to increase continuously. The maximum value of the energy flux density increases significantly with the increase of the gap length. L plm =7.86×10 4 W / m 2 Increase to L plm =2.24×10 for 24mm 5 W / m 2 , expanding by nearly 3 times. It can be seen that when the armature-rail contact interface is in a transitional contact state where the plasma gap and the metal liquefaction layer coexist, the expansion of the plasma gap length will cause the discharge area of ​​the armature contact surface as the cathode to increase. According to formula (9) that characterizes the arc discharge heat source, it can be seen that arc discharge phenomena exist everywhere in the longer transition gap. L plm The increase in the arc discharge area expands from the interface end to the front end, and the arc discharge intensity and energy density increase accordingly. Therefore, the longer the plasma discharge gap, the more intense the arc discharge intensity and energy will be.

[0053] In the transitional contact state where the metal liquefaction layer and the plasma gap coexist, in order to explore the distribution law of the electrothermal coupling field when the plasma gap continuously replaces the metal liquefaction layer and expands to the armature head, the gap length is selected. L plm The spatial distribution characteristics of the current density and temperature along the pivot rail contact interface at 0.2ms are analyzed for 4mm, 8mm, 12mm, 16mm, 20mm, and 24mm. The analysis shows that under the transition contact state, the current density of different gap lengths has two peaks on the contact interface: one at the junction of the plasma gap and the metal liquefaction layer, and the other at the front end of the contact interface, and the first peak is larger. Among them, the current density distribution at the transition gap is uniform, and the values ​​at all locations are approximately 4.5×10 5 A / m 2, part of the pulse current in the surface track will gather on the upper and lower contact surfaces of the gap, forming an arc through the transition gap, and also providing sufficient charge for the arc to continue burning; and the current density distribution in the metal liquefaction layer area is similar to the complete fluid lubrication contact state when the metal liquefaction layer development length is equal to 28mm, and is concentrated at the head and tail ends of the liquefaction layer. L plm The maximum current density at the pintle-rail contact interface moves forward and continues to increase. This reflects that with the continuous splashing of the metal liquefied layer and viscous losses, the plasma discharge gap between the interfaces is continuously exposed. The pulse current can only be more concentrated in the shrinking high-conductivity liquefied layer, resulting in a further increase in the current density value. In short, the existence and development of the plasma gap significantly changes the spatial distribution of the current density at the pintle-rail contact interface.

[0054] The spatial distribution of the temperature at the pivot-rail contact interface in the transitional contact state exhibits an "increase followed by decrease" trend: the temperature gradually rises within the plasma gap, accelerating near the junction of the plasma gap and the metal liquefaction layer, reaching a peak at the LMF end region before gradually decreasing along the LMF head end. This is because, in the transitional contact state, the primary heat source at the pivot-rail contact interface is viscous frictional heat generated by the LMF. Influenced by the velocity trend effect and the current skin effect, the highest temperature is located at the LMF end, and the temperature decays toward both sides from there. In the plasma gap, although the arc temperature is always lower than the LMF temperature, the arc energy is highly concentrated at the protrusions on the rough metal surface, forming an extremely high order of magnitude energy flux density. At the same time, the electromagnetic force damage caused by the arc discharge and the oxidation of the metal significantly damage the contact surface microstructure, and ultimately the degree of damage to the pivot rail contact interface is higher than the LMF friction heat; and the arc discharge generates more heat at the junction of the plasma gap and the LMF, close to the LMF peak. This is because the current converges at the junction of the plasma gap and the LMF under the combined influence of the current skin effect and the velocity skin effect, thereby inducing higher thermal power, and the heat diffuses to the adjacent plasma gap area. As the plasma gap length increases, the heat generated by the arc discharge increases. L plm As the temperature of the contact interface between the pivot and the rail increases, the overall temperature distribution decreases, and the maximum temperature drops from 778.1℃ to 729.19℃. The main reason is that Figure 8 The viscous frictional heat in the LMF shown in the figure continues to decrease. In summary, the length change of the plasma gap and the transition arc discharge behavior are similar to those of the LMF and will significantly affect its spatial temperature distribution.

[0055] In summary, the development of the pivot-rail contact state will affect the electrothermal field coupling distribution at the pivot-rail contact interface, change the distribution characteristics of current density and temperature along the contact interface, and eventually cause transitional ablation accompanied by arcing.

[0056] The influence of the pivot-rail contact conditions on the contact interface characteristics and arc discharge parameters is explained below.

[0057] In the actual operation of the electromagnetic rail launcher, the wear and ablation of the contact interface between the armature and the rail are dynamic and random, and three contact states may exist simultaneously, namely, dry sliding, metal liquefaction layer, and plasma gap. Therefore, based on the development model of the armature-rail contact state, with the corner of the armature tail end as the coordinate origin and the armature launch direction as the positive, an arc discharge model between the armature and rail contact interfaces with three coexisting contact states was established, as shown in the figure. Figure 9 Among them, the length of the end plasma gap is 4mm, the length of the middle metal liquefaction layer is 12mm, the length of the front dry sliding contact interface is 12mm, and the average exposed roughness of the armature tail is Ra A Taken as 62μm. Considering the actual situation, the thickness of the metal liquefaction layer is analyzed in detail. h LMF and the roughness of the armature tail exposed in the gap Ra A The influence rules on contact interface and arc discharge parameters.

[0058] 1. Thickness of metal liquefaction layer.

[0059] The above only discusses the development length of the metal liquefaction layer L LMF The influence of the electric and thermal field coupling distribution on the contact interface of the pivot rail, but in reality, the solid aluminum alloy continues to melt under the action of high temperature, making the thickness of the metal liquefaction layer h LMF Add, select h LMF The contact distances are 20μm, 40μm, 60μm, 80μm and 100μm respectively, and the spatial distribution of current density and temperature at the pivot-rail contact interface when the three contact states coexist are studied.

[0060] The analysis shows that the current density at the pintle-rail contact interface has peaks at the two positions (4 mm and 16 mm) where the three contact states transition. The first peak (4.1 mm) is at the junction of the plasma gap and the metal liquefaction layer, and the peak value exceeds 1.5×10 6 A / m 2 , which is significantly higher than the 5.5×10 5 A / m 2Under the conditions where all three contact states coexist, the overall current density distribution along the pivot-rail contact interface follows a pattern: it is initially stable along the contact interface, then rises sharply to the first peak, then slowly decreases to the second peak, and finally slowly decreases in the dry sliding zone before recovering slightly at the front end. This corresponds to the current density distribution when only two contact states coexist, and the current density distribution when all three contact states coexist is equivalent to a spliced ​​continuity of the two contact states.

[0061] As the thickness of the metal liquefaction layer h LMF The internal current density amplitudes of the three states do not change much, but the current density peaks at the positions where the two contact states connect to each other are affected. h LMF Among them, the peak current density at 4mm increases with h LMF The peak current density at 16 mm decreases with the increase of h LMF This is because the increasing thickness of the liquefied layer causes its volume to increase, and the electrical conductivity of liquid aluminum is much lower than that of solid aluminum. Therefore, the resistance of the metal liquefaction layer accumulates and increases, and the current tends to flow through the dry sliding contact state with greater conductivity. As a result, the current density in the transition area from the metal liquefaction layer to the dry sliding contact state is higher, while the current density at the front end of the metal liquefaction layer is lower. This shows that the thickness of the metal liquefaction layer has a significant impact on the current density distribution at the junction of the pivot and rail contact state.

[0062] Analysis shows that when a plasma gap, a liquefied metal layer, and dry sliding contact conditions coexist, the spatial temperature distribution shows a trend of first increasing and then decreasing. Within the plasma gap, the temperature increases as it approaches the front end of the gap, reaching a peak (over 950°C) at the interface between the plasma gap and the liquefied metal layer. The temperature then gradually decreases within the liquefied metal layer, but rebounds slightly at the transition between the liquefied metal layer and the dry sliding contact state. Finally, the temperature rapidly decreases at the front end of the contact interface, reaching a minimum of approximately 650°C.

[0063] As the thickness of the metal liquefaction layer h LMF As the temperature increases, the overall temperature distribution of the pivot-rail contact interface will decrease slightly. h LMF =20μm with h LMF= 100μm, the corresponding maximum temperature difference is 22.98°C. Because the constant-pressure heat capacity of liquid aluminum is higher than that of solid aluminum, increasing thickness increases its heat capacity, reducing the temperature rise under the same heat source, resulting in a slight overall temperature decrease. Furthermore, due to the splashing, viscosity, vaporization, and sublimation of the metal liquefaction layer during launch, the rough surface at the end of the armature tail fin is gradually exposed, forming a plasma discharge gap behind the armature-rail contact interface. Therefore, the distribution of arc discharge in the plasma gap was studied under the coexistence of these three states, using energy flux density as a measure of arc discharge intensity. When arc discharge occurs between the armature and rail, 10 typical coordinate points on the armature rough surface (peak heights for raised points and valley depths for depressed points) were selected in the plasma gap to measure the energy flux density caused by arc erosion. The coordinates of the selected points are shown in Table 1.

[0064] Table 1. Horizontal and vertical coordinates of 10 points on the rough surface of the armature tail fin; .

[0065] Based on the 10 typical points and their coordinates on the rough surface of the armature tail fin, points 2 and 10 are lower than the contour baseline of the rough surface of the armature tail fin because of their negative vertical coordinates, which are deep valleys on the rough surface, while the rest are high peaks. In order to explore the distribution of arc discharge energy density in the plasma gap on the rough surface and the thickness of the metal liquefaction layer h LMF The influence of h LMF The arc energy flux density change diagrams of typical points are drawn as the horizontal and vertical coordinates increase, as shown in Figure 10-11 As shown in the figure, it can be seen that in the horizontal axis direction, the points with higher arc energy flow density are 1, 3, 4, and 5, among which point 4 is the highest. h LMF =20μm reaches 109960W / m 2 , with coordinates of (1.376, 0.14). Next are point 1 (0, 0.035), at the inflection point at the end of the armature tail, and points 3 (0.935, 0.081) and 5 (1.620, 0.073), which are closer to point 4. After point 6 (2.056, 0.017), the arc energy flux density gradually decreases at points 7 (2.497, 0.048), 8 (2.815, 0.085), 9 (3.421, 0.046), and 10 (3.937, -0.151). Point 2 (0.604, -0.149) is particularly unusual. While its horizontal coordinate is small, its vertical coordinate is the smallest, its vertical distance from the track surface is the greatest, and its energy flux density is the lowest, approaching that of point 10. This demonstrates that the arc energy flux density does not change monotonically with the horizontal coordinate.

[0066] As the vertical coordinate increases, the arc energy flux density does not show a trend of continuous growth. The point with the maximum arc energy flux density is still point 4, followed by point 5, point 1 and point 3. Point 4 is the highest peak of the armature rough surface and is the shortest distance from the inner side of the track. Points 10 and 2, where the arc energy flux density is the lowest, are the deep valleys of the rough surface, both of which are negative values. The vertical coordinates of points 7 and 8 are similar to those of points 3 and 5, but the energy flux density is lower. Combining the distribution of the horizontal and vertical coordinates, the arc energy flux density is mainly concentrated at the height of the raised peaks with smaller horizontal coordinates and larger vertical coordinates. This is because the height of the raised peaks is closest to the inner surface of the track, the gas gap resistance is the smallest, and arc discharge is easy to occur. The energy flux density is significantly weakened away from the end of the armature tail fin or the deep valley of the rough surface. Therefore, the peak height of the raised peak at the end of the tail fin is the area where arc discharge and ablation are most serious. Thickness of metal liquefaction layer h LMF The distribution of energy flux density is weakly affected. h LMF The arc energy density at each point is slightly higher than several thousand W / m 2 's growth, and in actual exercise, h LMF The maximum is also within about 100μm, so it will not significantly change the distribution law of arc energy flux density.

[0067] 2. Surface roughness of the armature tail fin.

[0068] The height of the convex peaks on the rough surface of the armature tail end will cause the arc energy flux density to accumulate, while the average roughness of the surface curve Ra The increase makes the peak height of the convex higher and the maximum peak height closer to the track discharge surface. Therefore, in addition to the thickness of the metal liquefaction layer, the roughness of the armature tail surface Ra A As another contact condition between the pivot rail, it also affects the contact interface and arc discharge parameters. According to formula (1), select Ra A The values ​​are 6.1μm, 32μm, 62μm, 100.8μm and 148μm respectively. Ra A The variation rules of the lower pivot rail contact interface parameters and arc discharge parameters, such as Figure 12 As shown. Ra A With the increase of , the maximum temperature of the armature, rail, metal liquefaction layer and plasma gap has no obvious change, indicating that the roughness of the armature tail has no effect on the overall temperature, and the temperature distribution characteristics are mainly determined by the contact state of the armature and rail. Ra A Increased gradually, from 2.92×10 6 A / m2 ( Ra A =6.1μm) to 2.72×10 6 A / m 2 ( Ra A =148μm). As the maximum value of arc energy flux density increases Ra A Increased rapidly, from 4.19×10 4 A / m 2 ( Ra A =6.1μm) to 2.9 × 10 5 A / m 2 ( Ra A =148μm). This is because Ra A The increase in the armature surface profile increases the maximum peak height, shortening the distance between the discharge cathode on the armature surface and the discharge anode on the rail surface. This reduces the impedance of the gas gap between the two electrodes, prompting arc discharge to occur. The arc energy density concentrated at the peak height will become increasingly larger. As the arc discharge intensifies, more current and charge will flow through the plasma gap to form a high-energy arc discharge channel, thereby reducing the residual current and charge flowing through the contact interface, thereby reducing the current density at the armature-rail contact interface.

[0069] In this example, based on a magnetohydrodynamic arc discharge model across the contact interface, the distribution patterns of current density and temperature along the contact interface during the development phase of the pivot-rail contact state were studied. Considering the coexistence of multiple contact states during actual launch, the effects of two pivot-rail contact conditions, namely the thickness of the metal liquefaction layer and the surface roughness of the armature fin, on the contact interface and arc discharge parameters were investigated. The main conclusions are as follows: 1. Based on the theory of spatial frequency and elementary waves, the sum of trigonometric functions expanded by Fourier series was used to synthesize the real track rough surface data with completely random distribution, and a geometric model of the pivot-rail contact interface considering damage roughness was constructed. Based on this model, combined with the coupling equivalent equations of electric field, magnetic field, thermal field and fluid field, a magnetohydrodynamic multi-physics field coupling model of the arc discharge development between the pivot and rail was finally constructed.

[0070] 2. During the electromagnetic rail launch process, the contact state between the pintle and rail goes through the following stages: pintle-rail dry sliding contact state, mixed lubrication contact state with both pintle-rail dry sliding and metal liquefaction layer, and transitional contact state with both metal liquefaction layer and plasma gap. In the final transitional contact state, arc discharge and transitional ablation between the pintle and rail occur due to the splashing and viscosity of the metal liquefaction layer. The distribution patterns of the electrothermal field coupling at the pintle-rail contact interface in the three contact state stages are as follows: (1) When the pivot-rail is in dry sliding contact, the maximum current density is located at the front end of the pivot-rail contact interface, while the highest temperature is located at the end of the contact interface.

[0071] (2) In the mixed lubrication contact state where the pivot-rail dry sliding and the metal liquefaction layer coexist, the maximum temperature of the pivot-rail interface increases significantly due to the decrease in thermal conductivity of the metal liquefaction layer and the increase in constant-pressure heat capacity. As the length of the metal liquefaction layer increases, it first decreases and then increases; the maximum current density increases slightly; the maximum temperature position is at the end of the pivot-rail contact interface, and the maximum current density position moves from the front end to the end of the contact interface; when in a fully covered metal liquefaction layer (complete fluid lubrication state), the maximum current density and position are stable, but the maximum temperature drops significantly, and the position returns to about 6 mm at the end.

[0072] (3) In the transition contact state where the metal liquefaction layer and the plasma gap coexist, the maximum temperature and the maximum current density increase again; and the maximum current density increases with the length of the plasma gap. L plm As the gap length increases, the maximum temperature continues to decrease; both locations stabilize just before the junction of the plasma gap and the metal liquefaction layer. Increasing the gap length significantly increases the energy flux density, prompting transitional arcing discharge and transitional ablation in the plasma gap.

[0073] In summary, the evolution and changes in the pivot-rail contact state affect the electrothermal field coupling distribution at the pivot-rail contact interface, altering the current density and temperature distribution characteristics along the contact interface. When a plasma gap forms at the end of the pivot-rail contact interface, resulting in a transitional contact state, transitional arcing and transitional ablation begin to generate and develop in the gap.

[0074] 3. Considering the arc discharge model between the armature-rail contact interface in which three contact states coexist during the actual launch process, the influence of the metal liquefaction layer thickness and the armature tail surface roughness on the contact interface and arc discharge parameters is analyzed. The increase in the thickness of the metal liquefaction layer reduces the current density at the junction of the plasma gap and the metal liquefaction layer; the current density peak value in the transition zone between the metal liquefaction layer and the dry sliding contact state increases, while its overall temperature decreases slightly. However, the thickness of the metal liquefaction layer has no significant effect on the distribution of arc energy flux density in the gap, and the raised peak height of the rough surface at the end of the armature tail is still an area of ​​severe arc discharge and ablation. The roughness of the armature tail has no effect on the overall temperature of the device, but has an inhibitory effect on the maximum current density at the armature-rail contact interface and a promoting effect on the maximum arc energy flux density.

[0075] The rail surface damage results after the experiment show that with increasing frequency of use and number of launches, rail surface wear and ablation intensify, and the aluminum deposit layer thickens, leading to further increases in rail surface roughness. This worsens the wear and ablation of the armature surface, affecting its movement behavior within the barrel and launch quality, and may even cause longer-lasting and more intense arc ablation. For situations where the armature and rail completely lose contact and separate, the metal liquefaction layer is completely depleted, and arc ablation is most severe during the transition state, based on an established magnetohydrodynamic model, the inner side of the rail is set as the arc discharge anode and the armature contact surface as the arc discharge cathode. The dynamic development of arc morphology and parameters with launch time is explored, as well as the influence mechanism of the number of micro-contact points on the armature and rail, gap width, and rail roughness on the armature-rail contact interface and arc discharge.

[0076] The dynamic development of arc morphology and parameters is explained below.

[0077] In the arc discharge electromagnetic fluid dynamics model with multi-physics coupling, the width of the gap between the pivot rails is taken as d The average roughness of the track surface is 0.5mm. Ra R The arc shape, arc temperature and arc energy flux density in the plasma gap are studied as the emission time advances.

[0078] Figure 13-16 The dynamic development law of arc discharge temperature in the gap at the emission time of 0.5ms, 1.5ms, 2.5ms, and 3.5ms respectively. It can be seen that when the pintle-rail contact interface is completely in the transition contact state due to loss of contact, the arc temperature in the plasma gap is much higher than when multiple contact states coexist, and the maximum temperature reaches 1.74×10 7℃, far exceeding the armature-rail dry sliding contact state and the metal liquefaction layer lubricated contact state, indicating that the arc erosion energy is stronger. This is due to the rapid increase in arc energy caused by the expansion of the electrode area. The arc temperature distribution shows a pattern of highest arc temperature in the middle arc column and lowest arc temperature at the arc roots on both sides. As the firing time increases, the discharge arc temperature first decreases and then increases, and the severity of the erosion also changes accordingly, which is consistent with the experimental trend of rail damage first increasing and then decreasing from the rear end to the front end. The highest arc temperature occurs at 1.5ms, lagging behind the pulse current peak by 1.2ms. The air flow velocity in the fluid field is opposite to the armature firing speed. When the airflow passes through the narrow gap, its flow speed accelerates, causing the arc shape to change significantly. At 0.5ms, the arc is evenly distributed throughout the gap. From 1.5ms to 3.5ms, the arc shape is gradually blown to the rear end of the gap, elongated at the inflection point at the end of the armature tail fin, and overflows to the rear. The change of arc temperature with emission time is also related to the change of arc shape. At the beginning, the arc temperature is evenly distributed in the gap and concentrated at the peak height of the rough surface of the rail. The high temperature area of ​​the arc is concentrated at the rear end of the gap as the airflow blows and increases from the front end to the rear end along the gap. The highest temperature is always located at the tail end of the gap that overflows the pivot rail.

[0079] Depend on Figures 17-20 The dynamic development pattern of the arc energy flux density within the gap at launch times of 0.5ms, 1.5ms, 2.5ms, and 3.5ms, respectively, is shown. The development pattern of the energy flux density is completely consistent with the temporal distribution characteristics of the arc morphology and arc temperature, gradually concentrating from the initial uniform distribution to the rear end and rear region of the gap. In the direction perpendicular to the pivot-rail contact surface, the arc energy flux density decreases from the center of the arc column to the arc roots on both sides. The energy flux density in the fully transitioned pivot-rail contact state is much higher than when multiple contact states coexist, with the maximum value also occurring at 1.5ms, reaching 2.27×10 12 W / m 2 , located at the tail end of the arc overflow gap. Combining the arc temperature and energy flux density, it can be seen that when the transition covers the entire pintle-rail contact interface, the pintle-rail gap contact resistance increases significantly, the induced electromotive force between the cathode and anode electrodes increases significantly, and the electrode discharge area expands. This leads to extreme accumulation and fragmentation of plasma arc energy under the combined effects of higher potential and larger discharge area, causing extremely severe ablation damage to the rail and armature, and even potentially posing immeasurable safety risks to the entire device, such as explosion, impact, and irreversible damage to key components.

[0080] In this example, based on a magnetohydrodynamic model of arc discharge development at the pintle-rail contact interface, the dynamic development characteristics of the arc morphology and parameters in the pintle-rail gap were analyzed when the pintle-rail is in a state of complete transitional contact due to loss of contact. The influence mechanisms of three variables—the number of pintle-rail micro-contact points, the pintle-rail gap width, and the rail surface roughness—on the pintle-rail contact interface and arc discharge parameters were also analyzed. The main conclusions are as follows: When the entire pintle-rail contact interface is in a state of complete loss of contact, the ablation damage type transitions from transitional ablation to the most severe arc ablation. The plasma gap arc temperature is significantly higher than that in the mixed contact state. The arc temperature and energy flux density are highest at the mid-arc column and lowest at the arc root on the rail and armature surfaces, first increasing and then decreasing over time. The arc morphology is initially uniformly distributed, but is then blown to the rear of the gap by the moving airflow and extends beyond the gap.

[0081] Example 2 This embodiment provides an arc discharge simulation system under pivot-rail contact and complete loss of contact, including: a model construction module configured to construct track surface curves at different roughness levels by synthesizing randomly distributed track roughness surface data, thereby constructing a geometric model of the transition between the pivot-rail contact interface at different roughness levels, and based on the geometric model, constructing a magnetohydrodynamic simulation model of arc discharge between the pivot-rail contact interface that simultaneously considers multi-field coupling of electric field, magnetic field, thermal field, and fluid field; The simulation module for the pivot-rail contact state is configured to analyze the electrothermal field distribution at the pivot-rail contact interface in the pivot-rail dry sliding contact state, the mixed lubrication contact state in which the pivot-rail dry sliding coexists with a metal liquefaction layer, and the transitional contact state in which the metal liquefaction layer coexists with a plasma gap, based on a magnetohydrodynamic simulation model. This module determines how the maximum current density and temperature of the pivot-rail contact interface, as well as their respective positions within the pivot-rail contact interface, change with the contact state stages. Furthermore, based on a constructed arc discharge model between the pivot-rail contact interfaces in which the three contact states coexist, the module analyzes how the pivot-rail contact interface parameters and arc discharge parameters change under different metal liquefaction layer thicknesses and armature tail fin roughnesses. The complete loss of contact simulation module is configured to perform arc ablation simulation when the pivot rail is completely out of contact based on the magnetohydrodynamic simulation model, and obtain the change law of arc morphology, temperature and energy flux density in the plasma gap with the emission time, as well as the change law of pivot rail contact interface parameters and arc discharge parameters under different pivot rail micro-contact points, pivot rail gap width and rail surface roughness.

[0082] In further embodiments, there is also provided: An electronic device includes a memory and a processor, and computer instructions stored in the memory and executed on the processor, wherein the computer instructions complete the method described in embodiment 1 when executed by the processor.

[0083] A computer-readable storage medium is used to store computer instructions, and when the computer instructions are executed by a processor, the method described in Example 1 is performed.

[0084] A computer program product includes a computer program, which implements the method described in embodiment 1 when executed by a processor.

[0085] For the sake of brevity, the specific implementation methods of the above embodiments are not described again here.

[0086] Although the above describes the specific embodiments of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without any creative work are still within the scope of protection of the present invention.

Claims

1. A method for simulating arc discharge under pivot-rail contact and complete loss of contact, characterized in that: include: By synthesizing randomly distributed track roughness surface data, we construct track surface curves at different roughness levels, and then build a geometric model of the transition between the pivot-rail contact interface under different roughness levels. Based on this geometric model, we build a magnetohydrodynamic simulation model of arc discharge between the pivot-rail contact interface that simultaneously considers the multi-field coupling of electric, magnetic, thermal, and fluid fields. Based on a magnetohydrodynamic simulation model, the electrothermal field distribution at the pivot-rail contact interface was analyzed during the pivot-rail dry sliding contact state, the mixed lubrication contact state where the pivot-rail dry sliding coexists with a metal liquefaction layer, and the transitional contact state where the metal liquefaction layer coexists with a plasma gap. The maximum current density, maximum temperature, and respective positions of the pivot-rail contact interface were determined as the contact state phases changed. Furthermore, based on a constructed arc discharge model between the pivot-rail contact interfaces in the three coexisting contact states, the variation patterns of the pivot-rail contact interface parameters and arc discharge parameters were analyzed under different metal liquefaction layer thicknesses and armature tail fin roughnesses. According to the magnetohydrodynamic simulation model, arc ablation simulation was carried out when the pivot rail was completely out of contact. The variation patterns of arc morphology, temperature and energy flux density in the plasma gap with emission time were obtained, as well as the variation patterns of pivot rail contact interface parameters and arc discharge parameters under different numbers of pivot rail micro-contact points, pivot rail gap widths and rail surface roughness.

2. The arc discharge simulation method under the conditions of pivot rail contact and complete loss of contact according to claim 1, characterized in that: The sum of trigonometric functions expanded by Fourier series is used to synthesize the real track rough surface data with completely random distribution, so as to construct the geometric model of the transition of the pivot-rail contact interface under different roughness. for: ； in, P Amplitude The proportionality coefficient of υ is the spatial frequency, a ( υ ) is the amplitude Multiply by a random function with a Gaussian distribution g ( υ ) generates an amplitude, φ ( υ ) is the phase angle, ± V is the maximum and minimum cutoff value of the spatial frequency, w ( υ ) is a uniform random function, is the spectral index.

3. The arc discharge simulation method under the conditions of pivot rail contact and complete loss of contact according to claim 1, characterized in that: In the dry sliding contact state of the pivot-rail, at the same time, the spatial distribution law of the current density along the pivot-rail contact interface shows a trend of first decreasing and then increasing. The maximum current density is located at the front end of the pivot-rail contact interface, and the highest temperature is located at the end of the pivot-rail contact interface. In the mixed lubrication contact state stage where the pivot-rail dry sliding and the metal liquefaction layer coexist, the metal liquefaction layer begins to appear from the rear position of the armature tail wing with the highest temperature, and gradually develops towards the armature head as the launch progresses until it covers the entire pivot-rail contact interface. The maximum temperature of the pivot-rail contact interface experiences a change pattern of first decreasing and then increasing as the length of the metal liquefaction layer grows. The position of the maximum temperature is at the end of the pivot-rail contact interface, and the position of the maximum current density shifts from the front end to the end of the pivot-rail contact interface. When the metal liquefaction layer develops to cover the entire pivot-rail contact interface, the pivot-rail contact state is a fully fluid lubrication contact state. In this contact state, the maximum current density and its location remain unchanged, the maximum temperature decreases, and the maximum temperature is located at the end of the pivot-rail contact interface. In the transitional contact state stage where the metal liquefaction layer and the plasma gap coexist, the maximum temperature is restored and the maximum current density increases; as the length of the plasma gap increases, the maximum current density continues to increase and the maximum temperature continues to decrease; the locations of the maximum temperature and maximum current density are always located at the connection point between the plasma gap and the metal liquefaction layer; transitional arc discharge and transitional ablation occur in the plasma gap, and the increase in gap length leads to an increase in the arc discharge energy flux density.

4. The arc discharge simulation method under the conditions of pivot rail contact and complete loss of contact according to claim 1, characterized in that: When the three contact states coexist, the armature-rail contact interface parameters include the maximum armature temperature, the maximum rail temperature, the maximum metal liquefaction layer temperature, and the maximum plasma gap temperature; the arc discharge parameters include the maximum current density at the armature-rail contact interface and the maximum energy flux density of the arc discharge; When the thickness of the metal liquefaction layer gradually increases, the maximum current density amplitude decreases at the position where the plasma gap connects with the metal liquefaction layer, and the maximum current density peak increases at the position where the metal liquefaction layer transitions to the dry sliding contact state. The change in the thickness of the metal liquefaction layer has no effect on the contact interface parameters of the pintle rail and the maximum energy flux density of the arc discharge. The roughness of the armature tail fin has no effect on the armature-rail contact interface parameters, but has a weakening effect on the maximum current density and a promoting effect on the maximum energy flux density.

5. The arc discharge simulation method under the conditions of pivot rail contact and complete loss of contact according to claim 1, characterized in that: When the armature and rail are completely out of contact, the spatial distribution characteristics of the arc temperature and arc energy flux density are that the temperature and energy flux density in the middle arc column are the highest, and the arc root temperature and energy flux density at the two side rails and armature surfaces are the lowest. The temporal distribution characteristics are that the arc temperature and arc energy flux density first increase and then decrease; the arc shape is initially distributed uniformly in the gap, and then the arc shape is gradually blown to the rear of the gap by the moving airflow, and is stretched at the inflection point at the end of the armature tail wing and overflows to the rear of the armature-rail gap.

6. The arc discharge simulation method under the conditions of pivot rail contact and complete loss of contact according to claim 1, characterized in that: When the armature and rail are completely out of contact, the armature-rail contact interface parameters include the maximum armature temperature, the maximum rail temperature, and the maximum plasma gap temperature; the arc discharge parameters include the maximum current density at the armature-rail contact interface and the maximum energy flux density of the arc discharge; The increase in the number of micro-contact points of the pivot rail leads to a decrease in the gap contact resistance, which in turn causes a decrease in the pivot rail contact interface parameters and arc discharge parameters. Under the synergistic influence of the pivot-rail gap width and the rail surface roughness, for the maximum armature temperature, only the increase of the pivot-rail gap width causes the maximum armature temperature to increase; for the maximum rail temperature, both the increase of the pivot-rail gap width and the increase of the rail surface roughness cause the maximum rail temperature to increase; for the maximum plasma gap temperature, only the increase of the pivot-rail gap width causes the maximum plasma gap temperature to increase; for the maximum current density, both the decrease of the pivot-rail gap width and the increase of the rail surface roughness increase the maximum current density; for the maximum energy flux density, the increase of the pivot-rail gap width and the increase of the rail surface roughness both increase the maximum energy flux density.

7. An arc discharge simulation system under pivot rail contact and complete loss of contact, characterized in that: include: a model construction module configured to construct track surface curves at different roughness levels by synthesizing randomly distributed track roughness surface data, thereby constructing a geometric model of the transition between the pivot-rail contact interface at different roughness levels, and based on the geometric model, constructing a magnetohydrodynamic simulation model of arc discharge between the pivot-rail contact interface that simultaneously considers multi-field coupling of electric field, magnetic field, thermal field, and fluid field; The simulation module for the pivot-rail contact state is configured to analyze the electrothermal field distribution at the pivot-rail contact interface in the pivot-rail dry sliding contact state, the mixed lubrication contact state in which the pivot-rail dry sliding coexists with a metal liquefaction layer, and the transitional contact state in which the metal liquefaction layer coexists with a plasma gap, based on a magnetohydrodynamic simulation model. This module determines how the maximum current density and temperature of the pivot-rail contact interface, as well as their respective positions within the pivot-rail contact interface, change with the contact state stages. Furthermore, based on a constructed arc discharge model between the pivot-rail contact interfaces in which the three contact states coexist, the module analyzes how the pivot-rail contact interface parameters and arc discharge parameters change under different metal liquefaction layer thicknesses and armature tail fin roughnesses. The complete loss of contact simulation module is configured to perform arc ablation simulation when the pivot rail is completely out of contact based on the magnetohydrodynamic simulation model, and obtain the change law of arc morphology, temperature and energy flux density in the plasma gap with the emission time, as well as the change law of pivot rail contact interface parameters and arc discharge parameters under different pivot rail micro-contact points, pivot rail gap width and rail surface roughness.

8. An electronic device, characterized in that: The method comprises a memory and a processor, and computer instructions stored in the memory and executed on the processor, wherein when the computer instructions are executed by the processor, the method according to any one of claims 1 to 6 is completed.

9. A computer-readable storage medium, characterized in that Used to store computer instructions, which, when executed by a processor, complete the method according to any one of claims 1 to 6.

10. A computer program product, characterized in that The invention comprises a computer program, which is used to implement the method according to any one of claims 1 to 6 when the computer program is executed by a processor.

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