Gunpowder combustion energy high-power pulse power supply simulation method

Abstract

The invention discloses a gunpowder combustion energy high-power pulse power supply simulation method, and relates to the field of gunpowder combustion energy MHD power generation simulation, and the method comprises the steps: carrying out the simulation experiment of a gunpowder combustion energy muzzle impact wave based on a gunpowder combustion energy generator, and determining an impact wave overpressure calculation correction formula; according to the shock wave overpressure calculation correction formula, in combination with a muzzle brake design method, a magnet brake power generation channel model of gunpowder combustion energy MHD is constructed; based on the magnetic body retreating device power generation channel model, analyzing the distribution condition of gunpowder forces of different charges on multiple flow fields in a power generation channel by utilizing a finite element analysis method; the multi-flow-field distribution condition comprises the efficiency of the brake and the speed of the flow field in the chamber. The gunpowder combustion energy high-power pulse power supply simulation method can simulate the gunpowder combustion energy high-power pulse power supply.

Description

Technical Field

[0001] The present application relates to the field of simulation of MHD power generation from gunpowder combustion energy, and particularly to a simulation method for a high-power pulsed power supply for gunpowder combustion energy. Background Art

[0002] Currently, traditional fossil energy is facing depletion, and there is an urgent need to develop new energy technologies; moreover, the energy of launch gunpowder with huge energy is also being consumed and wasted in large quantities (only about 30% of the gunpowder energy consumed by launched projectiles can be utilized). Just in the United States, the average annual consumption of firearm ammunition (excluding artillery shells, rockets, missiles, etc.) reaches more than 900 million rounds. There is an urgent need to break through the utilization rate of gunpowder energy; in addition, for the special high-power pulsed energy technologies required for advanced electromagnetic propulsion, high-power lasers, etc. today, due to technical bottlenecks such as energy sources, energy storage, volume, weight, especially continuous firing performance, there is an even more urgent need to break through. It is necessary to explore a new path and explore new high-power pulsed power supply technologies.

[0003] When gunpowder is used as the energy source during the firing process of guns, cannons, etc., extremely complex physical and chemical reactions will occur in the limited space inside the barrel, manifested as phenomena such as gunpowder combustion, gas generation, state change, energy conversion, and projectile movement, and they interact with each other, and even overlap with each other. It is extremely difficult to study the MHD (Magnetohydrodynamics) generator principle developed by utilizing gunpowder combustion energy.

[0004] When designing the MHD power generation channel component of gunpowder combustion energy, first take a certain typical silencer or muzzle brake as the research object. Usually, a muzzle brake utilizes the action of gunpowder gas in the aftereffect period to provide a braking force to the gun (cannon) body to reduce the recoil energy of the gun, and it is also beneficial to the unified design of the gun mount.

[0005] Therefore, traditionally, for the performance of a muzzle brake, attention is often only paid to parameters such as its structural characteristic quantities, efficiency, and impulse characteristic quantities, while the research on the flow field and shock waves inside it, at the muzzle, etc. is rarely seen. These precisely reflect the flow field characteristics of the power generation channel of the present application. This is necessary and the first thing to conduct in-depth research for scientifically designing the structure of a magnetic muzzle brake and also serving as a power generation channel.

[0006] Since the MHD power generation technology from gunpowder combustion energy stems from the process of conventional projectile launch, only through firing tests on the gunpowder combustion energy (manifested as gunpowder force) at the firing range can the magnitude of the shock wave pressure at corresponding positions such as inside the barrel and the muzzle brake be obtained, and then the power generation channel of the muzzle brake can be effectively designed to see if it can still meet the requirements of MHD power generation from gunpowder combustion energy. Therefore, simulating the high-power pulsed power supply for gunpowder combustion energy is an urgent matter to be solved at present. Summary of the Invention

[0007] The purpose of this application is to provide a simulation method for a high-power pulse power supply with gunpowder combustion energy, which can simulate the high-power pulse power supply with gunpowder combustion energy.

[0008] To achieve the above object, this application provides the following solutions:

[0009] In the first aspect, this application provides a simulation method for a high-power pulse power supply with gunpowder combustion energy, including:

[0010] Based on a gunpowder combustion energy generator, conduct a simulation experiment on the muzzle shock wave of gunpowder combustion energy to determine the correction formula for calculating the shock wave overpressure;

[0011] According to the correction formula for calculating the shock wave overpressure, combined with the muzzle brake design method, construct a magnetic body brake generator channel model for MHD with gunpowder combustion energy;

[0012] Based on the magnetic body brake generator channel model, use the finite element analysis method to analyze the distribution of multi-fluid fields in the generator channel under different powder forces of the charge; the distribution of the multi-fluid fields includes the muzzle brake efficiency and the flow field velocity in the chamber.

[0013] According to the specific embodiments provided by this application, the following technical effects are disclosed: This application provides a simulation method for a high-power pulse power supply with gunpowder combustion energy. By combining the simulation experiment method, the muzzle brake design method, and the finite element analysis method, a magnetic body brake generator channel model for MHD with gunpowder combustion energy is constructed, and the distribution of multi-fluid fields in the generator channel under different powder forces of the charge is analyzed, realizing the simulation of the high-power pulse power supply with gunpowder combustion energy and filling the gap in the field of simulating the high-power pulse power supply with gunpowder combustion energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of this application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0015] Figure 1 It is the flow chart of the simulation method for the high-power pulse power supply with gunpowder combustion energy provided by this application;

[0016] Figure 2 It is the schematic diagram of the numerical simulation scheme of the combustion energy shock wave under different charges at each test point provided by this application;

[0017] Figure 3 It is the partial simulation result schematic diagram of the numerical simulation scheme of the combustion energy shock wave under different charges provided by this application; among them, Figure 3In (a) is a schematic diagram of the simulation results of Scheme a; Figure 3 In (b) is a schematic diagram of the simulation results of Scheme b;

[0018] Figure 4 This is a schematic diagram of the test scheme for simulating the shock wave overpressure of the gunpowder charge in the present application;

[0019] Figure 5 This is a schematic diagram of the gunpowder energy MHD power generation system model provided by the present application;

[0020] Figure 6 This is a cross-sectional view in the x-y direction of the gunpowder energy MHD power generation system model provided by the present application;

[0021] Figure 7 This is a cross-sectional view in the x-z direction of the gunpowder energy MHD power generation system model provided by the present application

[0022] Figure 8 This is a schematic diagram of the grid division of the gunpowder energy MHD power generation system model provided by the present application;

[0023] Figure 9 This is a schematic diagram of the unsteady output voltage of the gunpowder energy MHD provided by the present application;

[0024] Figure 10 This is a schematic diagram of the unsteady output current of the gunpowder energy MHD provided by the present application;

[0025] Figure 11 This is a schematic diagram of the unsteady output power of the gunpowder energy MHD provided by the present application;

[0026] Figure 12 This is a schematic diagram of the shock wave pressure distribution of the microelement of the power generation channel provided by the present application;

[0027] Figure 13 This is a schematic diagram of the power generation channel of the magnetic recoil absorber provided by the present application;

[0028] Figure 14 This is a schematic diagram of the finite element horizontal flow field simulation of the power generation channel of the magnetic recoil absorber provided by the present application;

[0029] Figure 15 This is a gas flow distribution diagram of the gunpowder gas acting on the recoil absorber provided by the present application;

[0030] Figure 16 This is a gas flow distribution diagram of the gunpowder gas of a typical recoil absorber provided by the present application;

[0031] Figure 17 This is a schematic diagram of the three-dimensional structure model of a typical muzzle brake provided by the present application;

[0032] Figure 18 This is a schematic diagram of finite element meshing processing of a typical muzzle brake provided in this application;

[0033] Figure 19 This is a schematic diagram of the simulation analysis of the flow field distribution of a typical muzzle brake provided in this application; wherein, Figure 19 (a) is a schematic diagram of a cross section with the opening facing upward to the right; Figure 19 (b) is a schematic diagram of the cross section with the opening facing downward to the right; Figure 19 (c) is a schematic diagram of the opening toward the right rear;

[0034] Figure 20 A schematic diagram of the structural model of the power generation channel of the optimized magnetic stripper provided in this application;

[0035] Figure 21 A schematic diagram of a finite element model of a power generation channel of an optimized magnet demagnetizer provided in this application;

[0036] Figure 22 This is a schematic diagram of the simulation analysis of the flow field distribution in the power generation channel of the magnet demagnetizer provided in this application; Figure 22 (a) is an overall schematic diagram of the opening facing right; Figure 22 (b) is a schematic diagram of a cross section with the opening facing right;

[0037] Figure 23 Schematic diagram of a finite element model for collaborative design of multi-field control related factors of the power generation channel provided in this application; Figure 23 (a) is a schematic diagram of the finite element model of the charge; Figure 23 (b) is a schematic diagram of the finite element model of the projectile; Figure 23 (c) is a schematic diagram of the finite element model of the barrel; Figure 23 (d) is a schematic diagram of the finite element model of the launch process;

[0038] Figure 24 A schematic diagram of the two-dimensional muzzle flow field pressure distribution provided in this application;

[0039] Figure 25 Schematic diagram of the 3D model of the power generation channel and load Gambit analysis provided in this application;

[0040] Figure 26 This is a schematic diagram of the model of the generator and channel components in the recoil brake provided in this application. DETAILED DESCRIPTION

[0041] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0042] To make the above objects, features, and advantages of the present application more obvious and understandable, the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0043] The embodiment of the present application provides a simulation method for a high-power pulsed power supply with gunpowder combustion energy. This method is executed by a computer device, which can be specifically executed by a computer device such as a terminal or a server alone, or jointly executed by a terminal and a server. In the embodiment of the present application, as Figure 1 shown, this method includes the following steps.

[0044] S1: Based on the gunpowder combustion energy generator, conduct a simulation experiment on the muzzle shock wave of gunpowder combustion energy to determine the correction formula for calculating the shock wave overpressure.

[0045] S2: According to the correction formula for calculating the shock wave overpressure, combined with the muzzle brake design method, construct a magnetic body brake generator channel model for gunpowder combustion energy MHD.

[0046] S3: Based on the magnetic body brake generator channel model, use the finite element analysis method to analyze the multi-flow field distribution in the generator channel under different powder forces; the multi-flow field distribution includes the brake efficiency and the flow field velocity in the bore.

[0047] In an exemplary embodiment, S1 can be replaced by the following steps.

[0048] S11: Based on the gunpowder combustion energy generator, combined with different charge structures and charge forms, conduct an AUTODYN-2D simulation experiment on the muzzle shock wave of gunpowder combustion energy to establish a numerical simulation scheme for the combustion energy shock wave under different charge conditions.

[0049] S12: According to the numerical simulation scheme for the combustion energy shock wave under different charge conditions, analyze the pressure distribution of the combustion energy shock wave at each point at the muzzle of gunpowder combustion energy under the powder charge structure and the bare charge condition.

[0050] S13: Determine the correction formula for calculating the shock wave overpressure according to the pressure distribution of the combustion energy shock wave.

[0051] In an exemplary embodiment, S11 can be replaced by the following steps.

[0052] S111: Based on a gunpowder energy generator, in combination with different charge structures and charge forms, use the Euler algorithm to determine the air domain specifications; the air domain specifications include dimensions, the direction along the projectile axis, and the direction along the projectile diameter.

[0053] S112: Based on the air domain specifications, fill the gunpowder charge and the solid wall material into the air domain according to the set density, and based on the solid wall boundary conditions, let the shock wave pressure freely flow out from the boundaries of the air domain except the solid wall boundary; meanwhile, along the direction of the projectile diameter, set observation points in sequence from the ignition point, and based on various simulation test input conditions, determine the numerical simulation scheme of the energy release shock wave at each observation point under different charge conditions; the simulation test input conditions are jointly composed of different gunpowder charge diameters, lengths, and material columns of the charge, whether it is a bare charge, and the solid wall thickness.

[0054] In an exemplary embodiment, S13 can be replaced by the following steps.

[0055] S131: Verify and correct the coefficients in the empirical formula for the bare charge according to the energy release shock wave pressure distribution to determine the corrected coefficients.

[0056] S132: Determine the corrected formula for calculating the shock wave overpressure according to the corrected coefficients and the gunpowder charge parameters with solid wall boundaries; the gunpowder charge parameters include the explosive equivalent, the filling ratio of the charge, and the distance of the charge microelement from the center of pressure; the corrected formula for calculating the shock wave overpressure is for the gunpowder charge column with solid wall boundaries.

[0057] Furthermore, during the gunpowder energy muzzle shock wave test, first study the mechanism of gunpowder energy - gunpowder force generating shock wave pressure when the gunpowder charge is ignited to determine the test safety distance and obtain test data such as the shock wave pressure at necessary points. Because the main elements when the gunpowder energy generator is ignited and started include the primer, the gunpowder charge, the cartridge case, as well as the high - temperature and high - pressure gunpowder gas, shock wave, gunpowder gas plasma, etc. generated by igniting the gunpowder. Among them, the magnitude of the shock wave overpressure, the velocity of the projectile and the plasma are directly related to the projectile mass, projectile material, charge composition, and charge mass.

[0058] Simulation method: This application uses AUTODYN - 2D for numerical simulation, and uses the air domain Euler algorithm to study the influence of different charge structures, charge forms, etc. on the free - field shock wave overpressure to obtain the corrected formula for calculating the muzzle shock wave overpressure, as Figure 2 shown.

[0059] Figure 21-4 are the observation point positions. First, the numerical simulation is performed on the overpressure change of the energy shock wave of the gunpowder charge column placed on the ground in the free air field. The numerical simulation model is divided into three parts, namely the air domain, the gunpowder charge, and the solid wall boundary. The gunpowder charge finite element model adopts two-dimensional axisymmetry, and a 1 / 2 gunpowder charge simulation model is established. The numerical simulation scheme of the energy shock wave of different charges is constructed to numerically simulate and analyze the pressure distribution of the energy shock wave under the gunpowder charge structure and the bare charge.

[0060] The Euler algorithm is used in the air domain, with a size of 20m×10m, 10m along the projectile axis, and 20m in the projectile diameter direction. The gunpowder charge and solid wall materials are directly filled in the air Euler domain at a certain density; the solid wall boundary condition is used, and the shock wave pressure flows freely from the other boundaries of the air domain. At the same time, observation points are set in sequence starting from the ignition point along the projectile diameter direction, and the distance between each two observation points is 0.5m. In this way, the gunpowder column with different parameters such as gunpowder charge diameter, length, material, etc. can be combined with whether it is bare charge, solid wall thickness and material to form n types of simulation experiment input conditions or schemes, and the output simulation of each observation point can be obtained from the simulation of each observation point. The shock wave pressure distribution of each point at the muzzle, such as Figure 3 shown.

[0061] In an exemplary embodiment, S131 may be replaced by the following steps.

[0062] Using g(δ)=1-0.8923e -1.2712δ , determine the corrected coefficient; where g(δ) is the corrected coefficient; δ is the charge ratio.

[0063] In an exemplary embodiment, S132 may be replaced by the following steps.

[0064] use Determine the shock wave overpressure calculation correction formula; wherein Δp is the shock wave overpressure calculation correction formula; f() is the calculation correction function; m T is the explosive equivalent; r is the distance between the charge element and the pressure center.

[0065] Furthermore, based on the size of the shock wave that may be generated by the above-mentioned different gunpowder charges, the various test equipment required for the test and the safe distance of the test participants are calculated, and with the assistance of protective equipment, a practical test plan for the gunpowder ignition range is designed.

[0066] Test plan: Figure 4 shown.

[0067] Test location: Inside the blasting tower of the shooting range.

[0068] Test equipment: detonation tower, gunpowder charge simulation charge column, ignition device, synchronous controller, overpressure sensor, high-speed camera, transient recorder, high-power load, protective body, test power supply, cables, etc.

[0069] Test method: Place the gunpowder charge simulation charge column at the safe predetermined ignition position of the target range detonation tower. Here, the simulation charge column is divided into two forms, namely the bare charge column and the charge column with a solid wall boundary (replacing the cartridge case). Then, start the ignition device through the synchronous switch to ignite the simulation charge column. At the same time, the synchronous switch starts the high-speed photography and shock wave testing equipment. The high-speed photography records the form of gunpowder gas and the form of the muzzle shock flow field, etc. The transient recorder is used in conjunction with the overpressure sensor to test the shock wave overpressure parameters, and the empirical formula of the shock wave pressure Δp at each point is deduced and calculated as follows:

[0070]

[0071] In the formula, m T is the energy equivalent of gunpowder, and r is the distance from the charge microelement to the pressure center.

[0072] Then, according to the above test plan and test layout, Table 1 is the comparison table of the combustion energy overpressure results of the gunpowder charge column with a solid wall boundary. The combustion energy test results of the gunpowder charge column with a solid wall boundary are listed in Table 1 as shown below.

[0073] Table 1

[0074]

[0075] During the test, T-4 to T-8 are the test plans with different charge parameters such as bare charge and solid wall charge. From Table 1, the calculation results of the theoretical formula are still in good agreement with the test results, and the absolute value of the error between the two is within 15%. Thus, the credibility of the shock wave overpressure calculation formula for gunpowder charge is also verified, which lays a scientific theoretical basis for the design of magnetic recoil devices for high magnetic materials in terms of high-pressure impact, pressure distribution, and corresponding gunpowder charge design.

[0076] In an exemplary embodiment, S3 can be replaced by the following steps.

[0077] S31: Based on the magnetic recoil device power generation channel model, use the finite element analysis method to construct a high-dimensional finite element model of the projectile and a high-dimensional finite element model of the charge.

[0078] S32: Take the microstructural elements of each influencing factor of the power generation channel as the research object, and take the process of gunpowder energy burning to launch the projectile as the research carrier. According to the gunpowder combustion variable volume state equation, the high-dimensional finite element model of the projectile and the high-dimensional finite element model of the charge, analyze the gunpowder force of different charges on the multi-flow field distribution in the power generation channel.

[0079] In an exemplary embodiment, according to the equation of state for the variable volume of gunpowder combustion, the high-dimensional finite element model of the projectile, and the high-dimensional finite element model of the charge, the gunpowder force of different charges on the multi-flow field distribution in the power generation channel is analyzed, specifically including:

[0080] Based on the equation of state for the variable volume of gunpowder combustion, a gunpowder force action model of the projectile is established.

[0081] Based on the high-dimensional finite element model of the projectile and the high-dimensional finite element model of the charge, the micro-element velocity of the projectile is determined according to the gunpowder force action model.

[0082] Determining the flow field velocity in the bore according to the micro-element velocity of the projectile specifically includes:

[0083] Using to determine the flow field velocity in the bore; where, v y is the flow field velocity in the bore; v b is the micro-element velocity of the projectile; Δw i is the effective charge mass of the gunpowder charge micro-element; h i is the effective charge height, Δm i is the micro-element mass on the projectile surface; d i is the moving distance of the projectile micro-element.

[0084] Determining the brake efficiency according to the MHD magnetic brake power generation channel model of the gunpowder combustion energy specifically includes:

[0085] Using to determine the brake efficiency; where, η T is the muzzle brake efficiency; m is the mass of the projectile, ω is the charge mass, β is the aftereffect coefficient without a muzzle brake, and β T is the aftereffect coefficient with a muzzle brake.

[0086] Furthermore, Figure 5 is a schematic diagram of the MHD magnetic brake power generation channel model. Among them, the origin of the Cartesian coordinate is located at the center of the entrance section of the model. For the Figure 5 shown power generation channel, it mainly consists of a high-speed metal projectile MHD and the power generation channel. Among them, the high-speed metal projectile is used as an initial parameter to describe the size and velocity parameters of the projectile formed by the propellant gas. The high-speed metal projectile MHD (circular structure projectile, specific parameters are shown in the table) moves along the positive x-axis direction, the applied magnetic field is in the y direction, and the induced current is in the z direction.

[0087] Figures 6 - 7 are the corresponding cross-sectional dimensions in the x-z and y-z directions.

[0088] According to the model structure dimension diagram, use Solidworks software to draw the system physical model and import it into ICEMCFD for mesh generation. Structured meshing is adopted, as Figure 8 shown. The mesh is encrypted to improve the solution accuracy, and the drawn mesh is imported into Fluent software for 3D flow field and electromagnetic field characteristic analysis.

[0089] Then, use the pressure-based solver for unsteady solution, considering the gravity factor.

[0090] The k-ε model is adopted for the turbulence model, the energy equation is turned on, the MHD model is loaded, and the RANS equation of the VOF (Volume of Fluid) two-phase flow model is turned on.

[0091] The initial conditions of the flow field are realized through the Patch function, and the media flowing in at the inlet and flowing back at the outlet are both gases, that is, their volume fractions are 1.

[0092] The pressure-velocity coupling is PISO. For the spatial and temporal turbulence equations, the first-order upwind scheme is adopted. The PRESTO! is used for the pressure term solution, Compressive is used for the volume fraction, and the second-order upwind scheme is used for the kinetic energy direction.

[0093] Adopt a fixed-step long-time placement, with a time step of 2e -0.7 s (0.2 μs), and the maximum number of iteration steps is 26 steps.

[0094] Judge whether the calculation converges through the residuals (10 -6 ) and monitor the velocity of a certain typical cross-section.

[0095] For the VOF two-phase flow physical model of the gunpowder combustion energy MHD power generation system, select Table 2 as one of the typical parameters. Table 2 shows the numerical analysis calculation conditions. Among them, copper is used as the high-speed metal projectile material for the power generation working medium, the magnetic field loaded in the MHD power generation channel is 0.9 T, along the positive x-axis direction, the initial velocity of the high-speed metal projectile is given, and the velocity is u = 800 m / s (the MHD velocity of the high-speed metal projectile, and the corresponding volume term is 1). The outlet boundary condition is the atmospheric pressure environment.

[0096] Table 3

[0097]

[0098]

[0099] Figures 9 - 11 They are the voltage, current, and power curves extracted by the load respectively.

[0100] From Figures 9 - 11Analysis shows that there are three distinct stages in the pulsed electrical output waveform: The first stage is from 0 to 210 μs. At this time, the metal projectile magnetohydrodynamic microelement drives the gas movement at the head and tail. The current in the power generation channel mainly flows through the metal projectile and the electrode plate, and then to the load. As the metal projectile moves towards the load side, the plate resistance of the electrode plate continuously decreases, the electrode voltage drop decreases, the voltage on the load continuously increases, and the output current and voltage also increase accordingly. The second stage is from 210 to 380 μs. The metal projectile moves to the position where it contacts the load and the electrode plate. At this time, the current transfer between the electrode plate and the load changes from the previous local contact to surface contact. The current no longer flows in from the side but changes to flow in the positive direction with the electrode plate. At this time, the electrode resistance also tends to decrease, so the electrode voltage will still increase. Subsequently, as the metal projectile magnetohydrodynamic microelement gradually leaves the power generation channel, the output performance of the load gradually decreases. The third stage is when T > 380 μs. At this time, power generation relies on the high-speed gas plasma at the tail that has already been driven. In this stage, the speed of the gas will gradually and slowly decrease, showing an approximate straight line, and the corresponding output voltage, current, and power also gradually decrease.

[0101] Through numerical simulation, the typical working profile of gunpowder combustion energy MHD is verified, that is, at the beginning, the metal projectile magnetohydrodynamic microelement and the conductive gas at the tail convert the extracted magnetohydrodynamic energy into energy on the load through the electrode plate; subsequently, when the metal projectile moves out of the power generation channel, the gas plasma at the tail further conducts continuous current and continuously outputs power, which can improve the combustion energy utilization rate of the propellant.

[0102] At the moment of 263 μs, the peak output voltage is 13.15 V, the peak current is 18.31 kA, and the peak power of the load is 241 kW at this time.

[0103] Furthermore, based on the empirical formula of shock wave overpressure obtained from the above simulations and tests, and theoretically drawing on the traditional muzzle brake design method, a magnetic brake power generation channel model that can also be used for gunpowder combustion energy MHD can be designed.

[0104] However, in-depth research reveals that traditional muzzle brakes are used to adjust and control the gas flow rate, gas flow direction, and gas flow velocity during the aftereffect period of gun firing, generating a forward force, which can reduce the recoil kinetic energy and the force on the gun carriage. After the recoil is reduced to a certain extent, the mass of the gun carriage can be reduced, improving the mobility of the gun.

[0105] If a magnetic brake is adopted and used as a power generation channel, during the process of firing a projectile, shock waves, a flow field of gunpowder gas, an electromagnetic field, and a relatively stable supersonic plasma jet structure that continuously propagate outward will inevitably be generated in the brake channel, forming a complex multi-flow field inside and outside the chamber that is unsteady, multiphase, turbulent, and directional. Currently, there has been no systematic study on problems such as this type of multi-flow field power generation model and its analysis. Therefore, this application proposes a micro-element analysis and multi-field fine control method to analyze and design a brake power generation channel model.

[0106] Theoretical method: This application conducts a micro-element analysis of various influencing factors of the brake power generation channel. For example, micro-element structures such as the chamber interior, projectile structure, and its aerodynamic characteristics are used as the research objects, and the process of using the energy of gunpowder combustion to fire a projectile is used as the research carrier. Based on the variable volume state equation of gunpowder combustion and the finite element high-dimensional models of the projectile and charge, the influence of the powder force of different charges on the micro-element fluid velocity of the projectile, the flow field in the channel, etc. is analyzed.

[0107] That is, under different gunpowder charge structures, according to the reduced diameter length of the free volume of the chamber interior after gunpowder combustion, a powder force action model of the projectile is established:

[0108]

[0109] Among them, P is the chamber pressure of the powder force acting on the projectile, the powder force f = RT, R is the gas molecule constant, T is the temperature of the gunpowder gas, ω is the charge mass, ψ is the percentage of gunpowder burned, S is the cross-sectional area of the gun barrel, l is the distance that the projectile with a mass of m moves forward, and l ψ is the reduced diameter length of the free volume of the chamber, expressed as

[0110]

[0111] Among them, ρ p is the gunpowder density, Δ = ω / v 0 is the gunpowder loading density, l 0 is the reduced diameter length of the chamber volume, and α represents a correction amount related to the volume of gas molecules per unit mass, which is called the residual volume in interior ballistics.

[0112] Then, relevant factors such as the gunpowder charge and the projectile are divided into finite elements according to the micro-element idea, and the relationship between the flow field velocity v y in the chamber and the micro-element velocity v b of the projectile can be obtained, and then the distribution of the multi-flow field in the chamber can be analyzed.

[0113]

[0114] Among them, Δw i , h iare the effective charge mass and effective charge height of the propellant charge micro-elements, respectively, and Δm i , d i are the mass of the micro-element on the projectile surface and its moving distance, respectively.

[0115] Then, based on the unsteady combustion theory of the propellant, the structural characteristics and performance characteristic quantities of typical muzzles are studied. The structural model of the power generation channel of the muzzle is established with the above micro-element idea to facilitate the fine control of the channel flow field.

[0116] According to the unsteady aftereffect period theory, under different charges, the efficiency η of the muzzle T is calculated as:

[0117]

[0118] In the formula, m is the mass of the projectile, ω is the charge mass, β is the aftereffect coefficient without a muzzle, and β T is the aftereffect coefficient with a muzzle, and the calculation formula is:

[0119]

[0120] Among them, α is the specific volume, k is the resistance coefficient, p g and v 0 are the muzzle pressure and velocity, respectively, and ρ g is the density of the powder gas.

[0121] Thus, based on the calculated efficiency of the muzzle, as well as parameters such as the flow field velocity and projectile velocity in the bore, the structure of the power generation channel of the muzzle can be co-simulated and designed.

[0122] Finite element simulation method: Combining the above propellant charge characteristics, projectile aerodynamic characteristics, and barrel structural characteristics, jointly construct the micro-element structure of each relevant element of the power generation channel. Use the finite element to analyze the distribution of velocity, pressure, etc. in the bore, simulate and calculate the structural model of the MHD power generation channel of the powder combustion energy, and then make a secondary correction to preliminarily design a more suitable power generation channel structure. Through the analysis of magnetohydrodynamic characteristics such as the magnetic field distortion generated by the induced magnetic field, study the MHD generation mechanism of the powder combustion energy.

[0123] That is, based on explicit dynamics, combined with the propellant charge, projectile, and barrel finite element models by the Shock state equation of the powder impact, use the 3D-Euler unsteady equations with moving boundaries to analyze and calculate the pressure and flow field distribution of each micro-element of the power generation channel of the muzzle, and design the finite element simulation model of the power generation channel of the muzzle accordingly, as Figures 12 - 14 shown.

[0124] The finite element model and simulation of the power generation channel of the muzzle are as follows:

[0125] First, based on mathematical models such as the overpressure empirical formula and the muzzle brake efficiency of unsteady theory, the gas flow field of a typical muzzle brake under the action of powder force is analyzed, as Figure 15 shown.

[0126] When the gun is fired and the projectile exits the muzzle, the velocity of the powder gas is slightly higher than that of the projectile at the instant of exit, and the ram pressure is relatively large, and it is no longer restricted by the barrel and the projectile. In the case of installing a muzzle brake, part of the gas moves axially, and part of the gas will flow to the side holes after reaching the reflecting surface of the muzzle brake, thereby changing the overall flow direction of the gas, turning the direction of the synthetic gas flow to the radial side holes or even to the rear, rather than just forward. This part of the deflected gas impacts the baffle of the muzzle brake, and the force on the muzzle brake is forward, thus generating an impulse opposite to the recoil direction, and further reducing the recoil. The two-dimensional analysis of the gas control process during the aftereffect period of a typical muzzle brake is as Figure 16 shown.

[0127] Then, combined with the above typical two-dimensional structure of the muzzle brake, its three-dimensional model is constructed using Soildwords, as Figure 17 shown.

[0128] To further study the distribution of the pressure field and others of the micro-element structure of the muzzle brake, it is necessary to perform finite element mesh division on the muzzle brake with the micro-element idea, that is, import the three-dimensional model of the muzzle brake into the Abaqus preprocessing software, set the muzzle orientation to the positive direction of the Z-axis, the mesh is unified as triangular mesh, encrypt the mesh at its inflection points, and continuously adjust to reduce the distortion rate. The mesh division result is as Figure 18 shown.

[0129] Then, simulate a muzzle brake with a caliber of 105mm, made of elastic magnetic material, with a Young's modulus of 210000 Pa, a Poisson's ratio of 0.3, a uniform pressure distribution, a duration of 10 s, and a time step of 0.1 ms. Assume the initial muzzle velocity of the projectile is 1000 m / s. Import the three-dimensional structure of the muzzle brake into Abaqus for simulation analysis to study the flow field distribution of the muzzle brake during the aftereffect period, as Figure 19 shown.

[0130] From Figure 19 it can be seen that the overall force on this muzzle brake is relatively uniform, and there is basically no situation where the force on a single point is too large. Compared with the first and second chambers, the force on the third, fourth, and fifth chambers is more obvious. The closer to the barrel end, the more violently the high-temperature and high-pressure gas expands and does work after overflowing from the rear side holes, the greater the impulse on the inner wall of the chamber and around the side holes, the higher the requirement for the material strength of the third, fourth, and fifth chamber parts, and at the same time, the third, fourth, and fifth chamber parts also contribute more to the muzzle brake efficiency.

[0131] Based on the above analysis, the magnetic recoil brake is further optimized. The structure of the rear chamber and the arrangement of the side holes are improved. Combining with the unsteady theory, according to the principle that within a certain range, the efficiency of the recoil brake increases with the increase of the side hole size and the backward tilt angle. On the premise of ensuring the strength of the magnetic material, the size and inclination angle of the rear side holes are further increased, so that the gunpowder gas has a rapid accelerating expansion at the beginning of overflow. The optimized recoil brake channel model and finite element model are as Figures 20 - 21 shown.

[0132] Then, referring to the above simulation parameter settings, the three-dimensional structure and mesh division results of the optimized model of the recoil brake are imported into the ABAQUS analysis software for force distribution simulation. The simulation results are as Figure 22 shown.

[0133] From Figure 22 the simulation results, increasing the inner cavity at the tail of the recoil brake and opening larger strip-shaped side holes can well slow down the impact force of the first expansion acceleration of the high-temperature and high-pressure gunpowder gas on the inner wall and side holes of the cavity. The second expansion acceleration can also be better discharged from the two chambers of the original recoil brake at the head, making the overall force of the recoil brake model tend to be uniform and stable, which is beneficial to MHD. At the same time, it can also better play the role of the recoil brake, and the structure is more compact. It explores a scientific analysis method for the design of the power generation channel.

[0134] Therefore, based on the above principles and methods, 3D models of the projectile, charge, and barrel can be established. Then, using the finite element method, from the structural aspects of the charge microelement, projectile microelement, barrel microelement, and recoil brake microelement, by adjusting the charge or redesigning the power generation channel of the recoil brake and other technical measures, the internal flow field and coupled field of the chamber are analyzed to achieve fine control of multiple fields inside the power generation channel, so that the power generation channel of the recoil brake meets the power generation requirements. The established finite element models of relevant elements are as Figure 23 shown.

[0135] Based on Figure 23 each microelement model, the Lagrange method can be used to construct components such as the charge, projectile, and barrel. During the process of gunpowder combustion and projectile launch, the high-speed surface microelements of the projectile, the generated plasma, etc. are regarded as fluids. Then, the adaptive grid is used to reduce the microelement distortion and simulation calculation amount. The gunpowder gas filling model is established by the Euler method, and the flow field distribution analysis is carried out with ABAQUS. Finally, the numerical simulation solution of the launch flow field is carried out by the automatic fluid-structure coupling in LS-DYNA, and parameters such as the pressure distribution of the flow field inside the power generation channel or at the muzzle can be obtained, as Figure 24 shown.

[0136] Furthermore, when designing the prototype of the power generation channel of the magnetic recoil brake, two aspects should be considered. First, the design of the material and shape of the recoil brake should meet the recoil characteristics and aerodynamic characteristics as much as possible; second, the flow field formed by the design of the power generation channel of the recoil brake should meet the requirements of the effective magnetic field air gap and electrode design of the generator as much as possible. That is, the charge, projectile, barrel, plasma and recoil characteristics are considered in a coordinated manner, and the channel flow field and pressure characteristics are analyzed in conjunction with the above-mentioned microelement analysis method to design the power generation channel model of the recoil brake, such as Figures 25 - 26 shown.

[0137] Figure 25 The gunpowder combustion MHD generator assembly shown is constructed by combining the unsteady aftereffect theory with the Gambit grid analysis. It is designed as a hollow cylindrical magnet assembly, mainly composed of magnets, electrodes and loads. Of course, due to the various structural forms of the muzzle brake or silencer, only the simulation model that expresses the power generation principle is given here.

[0138] In this way, according to the simulation parameters, by changing the materials and structural dimensions of the propellant, recoil brake, etc., the flow field in the chamber or power generation channel can be controlled more precisely, so that high-speed projectiles or plasma can be used for power generation.

[0139] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0140] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A method for simulating a high-power pulse power supply for gunpowder combustion, characterized in that: include: Based on the gunpowder combustion generator, the gunpowder combustion muzzle shock wave simulation experiment was carried out to determine the shock wave overpressure calculation correction formula; According to the shock wave overpressure calculation correction formula and combined with the muzzle brake design method, a power generation channel model of the magnetic muzzle brake for gunpowder combustion MHD is constructed; Based on the model of the power generation channel of the magnetic recoil brake, the finite element analysis method is used to analyze the effect of the gunpowder force of different charges on the multi-flow field distribution in the power generation channel; the multi-flow field distribution includes the efficiency of the recoil brake and the flow field velocity in the chamber.

2. The method for simulating a high-power pulse power supply using gunpowder combustion energy according to claim 1, characterized in that: Based on the gunpowder combustion generator, a simulation experiment was conducted on the gunpowder combustion muzzle shock wave to determine the shock wave overpressure calculation correction formula, including: Based on the gunpowder combustion generator, combined with different charge structures and charge forms, AUTODYN-2D simulation experiments were conducted on the gunpowder combustion muzzle shock wave, and a numerical simulation scheme for the combustion shock wave under different charge conditions was established; According to the numerical simulation scheme of combustion shock wave under different charge conditions, the pressure distribution of combustion shock wave at each point at the muzzle of the gunpowder combustion under the gunpowder charge structure and bare charge conditions is analyzed; A shock wave overpressure calculation correction formula is determined according to the combustion energy shock wave pressure distribution.

3. The method for simulating a high-power pulse power supply using gunpowder combustion energy according to claim 2, characterized in that: Based on the gunpowder combustion generator, combined with different charge structures and charge forms, AUTODYN-2D simulation experiments were conducted on the gunpowder combustion muzzle shock wave, and a numerical simulation scheme for the combustion shock wave under different charge conditions was established, including: Based on the gunpowder combustion generator, combined with different charge structures and charge forms, the Euler algorithm is used to determine the air domain specifications; the air domain specifications include size, along the missile axis direction and the missile diameter direction; Based on the air domain specifications, gunpowder charges and solid wall materials are filled in the air domain at a set density, and based on the solid wall boundary conditions, the shock wave pressure is allowed to flow freely from the boundaries of the air domain except the solid wall boundaries; at the same time, observation points are set in sequence from the ignition point along the projectile diameter direction, and based on a variety of simulation test input conditions, the numerical simulation scheme of the combustion energy shock wave under different charge conditions at each observation point is determined; the simulation experiment input conditions are composed of different gunpowder charge diameters, lengths and materials of the charge column, whether it is bare charge and the solid wall thickness.

4. The method for simulating a high-power pulse power supply using gunpowder combustion energy according to claim 3, characterized in that: The shock wave overpressure calculation correction formula is determined according to the combustion energy shock wave pressure distribution, specifically including: Verifying and correcting the coefficients in the bare charge empirical formula according to the combustion energy shock wave pressure distribution, and determining the corrected coefficients; The correction formula for calculating the shock wave overpressure is determined according to the corrected coefficient and the parameters of the gunpowder charge with a solid wall boundary; the gunpowder charge parameters include the explosive equivalent, the charging ratio of the charge and the distance between the charge microelement and the pressure center; the correction formula for calculating the shock wave overpressure is the correction formula for calculating the shock wave overpressure of the gunpowder charge column with a solid wall boundary.

5. The method for simulating a high-power pulse power supply using gunpowder combustion energy according to claim 4, characterized in that: The coefficients in the bare charge empirical formula are verified and corrected according to the combustion energy shock wave pressure distribution, and the corrected coefficients are determined, specifically including: Using g(δ)=1-0.8923e -1.2712δ , determine the corrected coefficient; where g(δ) is the corrected coefficient; δ is the charge ratio.

6. The method for simulating a high-power pulse power supply using gunpowder combustion energy according to claim 5, characterized in that: The shock wave overpressure calculation correction formula is determined according to the corrected coefficient and the parameters of the gunpowder charge with a solid wall boundary, specifically including: use Determine the shock wave overpressure calculation correction formula; wherein Δp is the shock wave overpressure calculation correction formula; f() is the calculation correction function; m T is the explosive equivalent; r is the distance between the charge element and the pressure center.

7. The method for simulating a high-power pulse power supply using gunpowder combustion energy according to claim 6, characterized in that: Based on the power generation channel model of the magnet demagnetizer, the finite element analysis method is used to analyze the effect of the gunpowder force of different charges on the distribution of multiple flow fields in the power generation channel, including: Based on the power generation channel model of the magnet demagnetizer, a finite element high-dimensional model of the projectile and a finite element high-dimensional model of the charge are constructed by using a finite element analysis method; The microelement structure of each influencing factor of the power generation channel is taken as the research object, and the process of launching a projectile by burning gunpowder is taken as the research carrier. According to the gunpowder combustion variable volume state equation, the projectile finite element high-dimensional model and the charge finite element high-dimensional model, the gunpowder force of different charges on the distribution of multiple flow fields in the power generation channel is analyzed.

8. The method for simulating a high-power pulse power supply using gunpowder combustion energy according to claim 7, characterized in that: According to the variable volume state equation of gunpowder combustion, the projectile finite element high-dimensional model and the charge finite element high-dimensional model, the gunpowder force of different charges on the distribution of multiple flow fields in the power generation channel is analyzed, specifically including: According to the gunpowder combustion variable volume state equation, a gunpowder force action model of the projectile is established; Based on the projectile finite element high-dimensional model and the charge finite element high-dimensional model, determining the projectile micro-element velocity according to the gunpowder force action model; Determining the flow field velocity in the bore according to the micro-element velocity of the projectile; The efficiency of the recoil brake is determined based on the power generation channel model of the magnetic recoil brake of the gunpowder combustion energy MHD.

9. The method for simulating a high-power pulse power supply using gunpowder combustion energy according to claim 8, characterized in that: According to the micro-element velocity of the projectile, the velocity of the flow field in the chamber is determined, specifically including: use Determine the flow velocity in the chamber; where v y is the flow velocity in the chamber; v b is the micro-element velocity of the projectile; Δw i h is the effective charge mass of the microelement of gunpowder charge; i is the effective charge height, Δm i is the microelement mass of the projectile surface; d i is the distance of the projectile's infinitesimal movement.

10. The method for simulating a high-power pulse power supply using gunpowder combustion energy according to claim 8, characterized in that: According to the power generation channel model of the magnetic recoil brake of the gunpowder combustion MHD, the efficiency of the recoil brake is determined, specifically including: use Determine the efficiency of the recoil brake; where η T is the efficiency of the muzzle brake; m is the mass of the projectile, ω is the charge mass, β is the aftereffect coefficient when there is no muzzle brake, β T It is the aftereffect coefficient when equipped with muzzle brake.

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