Rapid prediction method for shape stability of bird body emitted by multistage electromagnetic coil

Abstract

The invention discloses a method for rapidly predicting the shape stability of a bird body emitted by a multistage electromagnetic coil, and the method comprises the steps: 1, inputting a structural parameter and an electrical parameter according to a bore-out speed requirement; 2, establishing a prediction model of the multistage electromagnetic coil transmitting device according to the parameters in the step 1; step 3, carrying out iterative calculation by adopting a forward difference method to obtain bird jerk after the cartridge case armature passes through the current-stage driving coil; 4, the bird body deformation stability in the current-level launching process is judged; 5, judging whether the armature displacement of the cartridge case meets the requirement or not, and if not, performing iteration at the current stage; if yes, executing the step 6; 6, setting the current, the mutual inductance and the mutual inductance gradient to be 0, and repeating the step 3 to carry out emission iterative calculation of the next-stage electromagnetic coil; 7, repeating the steps 4-6 until the prediction model reaches a preset out-of-bore speed; and step 8, outputting the final acceleration, displacement, speed and bird jerk curve of the cartridge case armature.

Description

Technical Field

[0001] The invention belongs to the technical field of electromagnetic launch, and relates to a method for quickly predicting the shape stability of a bird launched by a multi-stage electromagnetic coil. Background Art

[0002] Bird strikes are a major risk to aircraft engine blades, posing a significant safety hazard during flight. The impact of a bird colliding with a high-speed aircraft can severely damage engine blades and even cause engine failure, severely impacting flight safety. Therefore, bird strike testing is essential for aircraft engines. This simulates actual bird strike conditions in flight and assesses the blades' ability to withstand impact and potential damage, providing crucial insights for engine design and improvement.

[0003] Multi-stage electromagnetic coil launch technology utilizes the principle of contactless electromagnetic induction to efficiently convert electromagnetic energy into the kinetic energy of the projectile between the propulsion armature and the drive coil. This allows for the acceleration of birds of varying masses (loaded onto a magnetic cartridge) to high speeds. Furthermore, the variable-stage launch technology allows for precise control of the object's exit velocity. Systems based on this technology typically consist of a power supply (usually a capacitor bank), a drive unit, a launch tube, and a magnetic cartridge. The launch tube is equipped with fixed, independent drive coils that interact with the coils or armature on the magnetic cartridge via magnetic coupling. During operation, the magnetic cartridge generates an induced current in the time-varying magnetic field of the pulse capacitor bank, which in turn generates a corresponding Lorentz force, accelerating it. Furthermore, electromagnetic induction coil launchers are not only durable and reliable, but also relatively low in launch and maintenance costs. Therefore, electromagnetic induction coil launch technology has demonstrated significant development potential in various fields, including military, aerospace, and industry, and continues to be a focus of research both domestically and internationally. Electromagnetic launch technology has also become an emerging method for launching birds in bird strike testing.

[0004] During the multi-stage electromagnetic launch process, numerous structural parameters, such as the inductance, capacitance, resistance, and discharge voltage of each drive coil, the thickness and number of turns of each drive coil, and the bird's mass, are involved. Furthermore, coupling between these parameters occurs, such as magnetic coupling when two adjacent drive coils are energized sequentially. These factors can affect the accuracy of key launch parameters such as the bird's exit velocity and acceleration, thereby interfering with the simulation performance of bird strike tests. Furthermore, the high cost of building a bird strike electromagnetic launch system hinders the conduct and maintenance of tests. In particular, birds are typically constructed of soft and skeletal materials, which deform when subjected to force. When the force changes too dramatically, the bird can easily be damaged, even crushed or ruptured, before striking the blades after exiting the launch chamber, severely impacting its flight posture. Therefore, it is necessary to study the deformation stability of birds subjected to blade strikes. According to Newton's second law, the rate of change of force applied to an object can be indirectly characterized by the rate of change of acceleration, which is the derivative of acceleration, known as "jerk." For a soft bird during launch, greater jerk means more dramatic acceleration changes, which intensifies the strain cycles within the material's microstructure. This can cause premature damage, crushing, and rupture of the bird before it collides with the blades, affecting its shape stability. Therefore, using a discriminant formula related to jerk to measure the stability of the bird's deformation is a better assessment method.

[0005] Numerous literature reports on methods for predicting and analyzing electromagnetic coil launch performance parameters. Chinese patent application CN116306071A employs a finite element method combined with an equivalent circuit analysis method, dividing the track into finite elements. By placing an armature at the end of each element and performing iterative calculations, a relatively realistic electromagnetic railgun launch process is obtained. However, using displacement as a variable makes it difficult to determine the temporal trends of key parameters, hindering the accurate prediction of parameters such as the projectile's final launch velocity and acceleration. Chinese patents CN113049205A and CN117554017A, among others, have investigated parameter calculations for bird strike test devices based on electromagnetic launch technology. However, these methods only cover single-stage electromagnetic launch and fail to consider the high acceleration generated by multi-stage electromagnetic coils, their impact on the bird, and the potential for bird fragmentation. Furthermore, while some researchers have focused on predicting and optimizing key parameters of electromagnetic coil launchers, such as muzzle velocity, acceleration, launch efficiency, and trigger timing, no research has examined the impact of jerk on bird launch performance, nor on the effects of muzzle velocity and launch efficiency. For example, Chinese patent application CN116720327A uses a control variable method and a game aggregation model to determine the combined weights of multiple key parameters, including trigger position, coil turns, capacitance, discharge voltage, and the aspect ratio of the drive coil and projectile. However, it fails to address the impact of jerk on launch results. Chinese patent application CN112069703A achieves global optimization of the electromagnetic coil launch system by constructing launch performance samples, optimizing target samples, and constraining target samples. However, it only addresses acceleration fluctuations and peak acceleration, without explaining their impact on launch performance or considering factors related to projectile launch stability.

[0006] In addition, some scholars have also studied the prediction of multi-stage electromagnetic coil launch performance in public papers. For example, the papers "A Method for Optimizing the Magnetic Field Configuration of an Electromagnetic Coil Launcher" and "Research on the Stationary Electromagnetic Force of a Single-Stage Synchronous Induction Coil Gun" explore the impact of magnetic field configuration and distribution on the launch performance of electromagnetic coil launchers, but do not consider the unevenness of the projectile coil current, which can lead to large errors in the calculation results. The papers "Simulation of the Interior Ballistic Process of a Three-Stage Synchronous Induction Coil Gun" and "Research on the Stationary Electromagnetic Force of a Single-Stage Synchronous Induction Coil Gun" use the current wire method to divide the projectile coil into several parts, but only calculate launch performance parameters such as projectile velocity, acceleration, and electromagnetic force. It should be emphasized that none of the above papers consider the impact of jerk on electromagnetic launch performance. Summary of the Invention

[0007] In order to solve the above technical problems, the purpose of the present invention is to provide a method for quickly predicting the stability of the bird's body shape launched by a multi-stage electromagnetic coil, using jerk as an indicator to objectively judge the stability of the bird's body deformation.

[0008] The present invention provides a method for quickly predicting the shape stability of a bird launched by a multi-stage electromagnetic coil, comprising:

[0009] Step 1: Based on the muzzle velocity requirements of the planned bird launch test, input the structural parameters, electrical parameters, and iterative initial parameters of the multi-stage electromagnetic coil launcher;

[0010] Step 2: Establish a prediction model for the multi-stage electromagnetic coil launcher based on the muzzle velocity requirements, structural parameters, and electrical parameters;

[0011] Step 3: Based on the prediction model, the forward difference method is used to iteratively calculate and solve the velocity, acceleration, displacement and jerk of the shell armature loaded with the bird after passing through the current primary drive coil;

[0012] Step 4: Use the jerk determination formula to determine the stability of the bird's body deformation during the current first-stage launch process;

[0013] Step 5: Determine whether the armature displacement of the shell loaded with the bird body meets the requirements. If not, continue to iterate at the current level; if so, execute step 6;

[0014] Step 6: Reset the drive coil current, the cartridge armature coil current, the mutual inductance between the cartridge armature coil and the drive coil, and the mutual inductance gradient to 0. Repeat step 3 to perform the next level electromagnetic coil launch iterative calculation and solve to obtain the displacement, velocity, acceleration, and jerk of the cartridge armature loaded with the bird after passing through the next level coil.

[0015] Step 7: Repeat steps 4-6 until the prediction model reaches the preset muzzle velocity requirement;

[0016] Step 8: Output the final acceleration, displacement, velocity, and bird jerk curve of the cartridge armature loaded with the bird body after the multi-stage electromagnetic coil is fired.

[0017] The present invention provides a rapid prediction method for the shape stability of a bird launched by a multi-stage electromagnetic coil. The method can predict in advance key launch parameters such as the exit velocity, acceleration, and jerk of the cartridge case armature or the bird in the electromagnetic launch system. The method can also adjust the launch performance of the electromagnetic launch system by changing the system parameters, thereby solving the problem of high cost of building an electromagnetic launch system for bird strike tests, improving the deformation stability of the bird during the launch process, and ensuring high computational efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a flow chart of a method for rapidly predicting the stability of a bird body launched by a multi-stage electromagnetic coil according to the present invention;

[0019] Figure 2 It is a prediction model diagram of a multi-stage electromagnetic coil launching device. DETAILED DESCRIPTION

[0020] like Figure 1 As shown, the present invention provides a method for rapidly predicting the shape stability of a multi-stage electromagnetic coil-launched bird, comprising:

[0021] Step 1: Based on the muzzle velocity requirements of the planned bird launch test, input the structural parameters, electrical parameters, and iterative initial parameters of the multi-stage electromagnetic coil launcher, specifically:

[0022] Step 1.1: Set the muzzle velocity of the bird.

[0023] Step 1.2: Set the electrical parameters and structural parameters of the multi-stage electromagnetic coil transmitter; the electrical parameters include: the self-inductance of the drive coil circuit L d , drive coil circuit resistance R d , drive coil circuit discharge capacitance C, drive coil circuit discharge voltage value U d ; Structural parameters include: drive coil loop radius r d 、Radius r of the armature coil of the shell loaded with bird body p , total mass of bird body and armature m p , the distance between the middle position of the two adjacent driving coils and the initial emission position.

[0024] Step 1.3: Divide the armature coil of the shell loaded with the bird into n equal parts according to the current wire method. The self-inductance of the armature coil loop of the jth shell is L pj , the resistance of the armature coil circuit of the jth cartridge case is R pj The mutual inductance between the jth cartridge armature coil and the drive coil is M dpj ,j=1,2,···,n.

[0025] Step 1.4: Set the total prediction time T and the time step Δt, and the number of cycles to i = T / Δt.

[0026] Step 1.5: Set the initial drive coil current I at time t = 0 d , cartridge armature coil current I p The electromagnetic force F on the shell armature loaded with the bird body, the velocity v of the shell armature loaded with the bird body, the acceleration a, the displacement s, and the jerk β of the bird body are all zero.

[0027] Step 2: Based on the muzzle velocity requirements, structural parameters, and electrical parameters, a prediction model for the multi-stage electromagnetic coil launcher is established. Specifically:

[0028] Step 2.1: According to the muzzle velocity requirements, structural parameters and electrical parameters, a prediction model of the multi-stage electromagnetic coil launcher is established. The prediction model includes the equivalent circuit model of the driving coil and the equivalent circuit model of the armature coil of the shell loaded with the bird body, such as Figure 2 shown.

[0029] The driving coil equivalent circuit model includes: a driving coil discharge switch Y, a driving coil energy storage capacitor C, and a driving coil circuit resistor R. d , self-inductance of the driving coil circuit L d and diode VD. The self-inductance of the driving coil circuit L d and the drive coil circuit resistance R d After being connected in series, it is connected in parallel with the diode VD, and then connected in series with the drive coil discharge switch Y and the drive coil energy storage capacitor C in sequence to form a closed loop; the drive coil loop resistance includes: capacitor resistance, discharge switch resistance, line resistance and drive coil resistance; the drive coil loop self-inductance includes: capacitor self-inductance, discharge switch self-inductance, line self-inductance and drive coil self-inductance.

[0030] The equivalent circuit model of the shell armature coil of the loaded bird body includes n shell armature coil equivalent circuits, and each shell armature coil circuit is composed of each shell armature coil resistance R p1 , R p2 ,…,R pn and the self-inductance L of each cartridge armature circuit p1 , L p2 ,…,L pn The series connection forms a closed loop; the resistance of each cartridge case armature coil includes: the line resistance and the resistance of each cartridge case armature coil; the self-inductance of each cartridge case armature circuit includes: the line resistance and the self-inductance of each cartridge case armature coil.

[0031] When the drive coil discharge switch is closed, the drive coil energy storage capacitor begins to discharge, the drive coil circuit generates current, and then generates an induced magnetic field. The induced magnetic field causes the armature coil circuits of each cartridge to generate induced current. The induced current is subjected to electromagnetic force in the induced magnetic field, causing the cartridge armature to move and be launched.

[0032] Step 2.2: Ensure that the damping coefficient of the drive coil circuit is in an overdamped state:

[0033]

[0034] Where ζ is the damping coefficient of the drive coil loop.

[0035] Step 3: Based on the prediction model, the forward difference method is used to iteratively calculate and solve the velocity, acceleration, displacement and jerk of the shell armature loaded with the bird after passing through the current primary drive coil. Specifically,

[0036] Step 3.1: Calculate the mutual inductance and mutual inductance gradient between the armature coil of each loaded bird and the current primary drive coil at the current time t based on the following equation:

[0037]

[0038] Among them, M dpj is the mutual inductance between the armature coil of the jth cartridge case and the current primary drive coil; is the mutual inductance gradient between the jth cartridge armature coil and the current first-level drive coil; μ is the vacuum magnetic permeability, z j K(k j ) and E(k j ) are the first and second elliptic integral formulas, respectively, θ is the amplitude of the elliptic integral; k j is the independent variable of the elliptic integral.

[0039] Step 3.2: Calculate the current derivative of the driving coil at the current time t based on the above known conditions and the derivative of the current in the armature coil of each loaded bird The calculation is as follows:

[0040] According to Kirchhoff's voltage law, the following equivalent circuit equation is constructed for the equivalent circuit of the driving coil;

[0041]

[0042] According to Kirchhoff's voltage law, the following equivalent circuit equation is constructed for the equivalent circuit of the armature coil of each loaded bird body;

[0043]

[0044] Among them, I d (t) is the driving coil current at time t, I pj (t) is the current of the armature coil of the jth cartridge case at time t; Substitute the known conditions into the above two equivalent circuit equations to calculate the current derivative of the drive coil and the current derivative of the armature coil of each cartridge case loaded with bird body.

[0045] Step 3.3: Calculate the driving coil current I at time t' based on the two current derivatives solved in step 3.2 d (t') and the armature coil current I of each loaded bird shell pj (t'):

[0046]

[0047] t'=t+Δt

[0048] Step 3.4: Calculate the electromagnetic force F on the armature of each loaded bird shell at time t' based on the two currents solved in step 3.3. j (t'):

[0049]

[0050] Then calculate the electromagnetic force F(t') on the shell armature loaded with the bird at time t':

[0051]

[0052] Step 3.5: Calculate the acceleration a(t') of the cartridge case armature loaded with the bird at time t' based on the electromagnetic force calculated in step 3.4:

[0053]

[0054] Step 3.6: Calculate the velocity v(t') of the cartridge case armature at time t':

[0055] v(t')=v(t)+a(t')Δt

[0056] Where v(t) is the velocity of the cartridge armature loaded with the bird at time t;

[0057] Step 3.7: Calculate the displacement s(t') of the cartridge case armature at time t':

[0058] s(t')=s(t)+v(t')Δt

[0059] Where s(t) is the displacement of the cartridge armature of the loaded bird at time t;

[0060] Step 3.8: Calculate the bird's jerk β(t') at time t':

[0061]

[0062] Step 3.9: Repeat steps 3.1-3.8 until the bird's displacement satisfies the requirement that the cartridge case armature loaded with the bird is located in the middle of the two-stage drive coil. The time curves of the bird's displacement, velocity, acceleration, and jerk corresponding to the first-stage coil can be obtained.

[0063] Step 4: Use the jerk determination formula to determine the stability of the bird's body deformation during the current first-stage launch process. Specifically:

[0064] Step 4.1: Select the maximum absolute value of jerk |β(max)| during the current first-stage launch process and establish the following jerk determination formula:

[0065]

[0066] Among them, α0 is the launch experience control proportional coefficient, which is between 0.85 and 1.15. β0 is the jerk reference value related to the high-g acceleration crushing or other bird material damage that may occur during bird launch. It is determined by performing a Hopkinson pressure bar test on the relevant materials of the bird, and represents the ability of the material constituting the bird to maintain its morphological stability after the influence of the alternating stress generated by the external force.

[0067] Step 4.2: If λ≤1, it means the bird's deformation is within an acceptable range and there is no damage, crushing, or cracking. You can proceed to the next step.

[0068] Step 4.3: If λ>1, it means that the bird body has been damaged by irresistible external forces, and it is inevitable that it will be damaged or crushed, making it difficult to maintain its shape stability. The iteration is terminated and the process returns to step 1 to adjust the structural and electrical parameters.

[0069] Step 5: Determine whether the armature displacement of the shell loaded with the bird body meets the requirements. If not, continue to iterate at the current level; if it meets the requirements, execute step 6, specifically:

[0070] According to the iterative drive coil level of the current bird-loading shell armature, determine whether the displacement of the bird-loading shell armature meets the requirements:

[0071] If s(t)<x m , then the requirements are not met, and the iteration continues at the current level; if s(t)≥x m , then the requirements are met, then go to step 6;

[0072] Among them, x m is the distance between the middle position of the mth and m+1th driving coils and the initial emission position.

[0073] Step 6: Reset the drive coil current, the cartridge armature coil current, the mutual inductance between the cartridge armature coil and the drive coil, and the mutual inductance gradient to 0. Repeat step 3 to perform the next level electromagnetic coil launch iterative calculation and solve to obtain the displacement, velocity, acceleration, and jerk of the cartridge armature loaded with the bird after passing through the next level coil.

[0074] Step 7: Repeat steps 4-6 until the prediction model reaches the preset muzzle velocity requirement;

[0075] Step 8: Output the final acceleration, displacement, velocity, and bird jerk curve of the cartridge armature loaded with the bird body after the multi-stage electromagnetic coil is fired.

[0076] The above description is only a preferred embodiment of the present invention and is not intended to limit the concept of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for rapidly predicting the shape stability of a bird launched by a multi-stage electromagnetic coil, characterized in that: include: Step 1: Based on the muzzle velocity requirements of the planned bird launch test, input the structural parameters, electrical parameters, and iterative initial parameters of the multi-stage electromagnetic coil launcher; Step 2: Establish a prediction model for the multi-stage electromagnetic coil launcher based on the muzzle velocity requirements, structural parameters, and electrical parameters; Step 3: Based on the prediction model, the forward difference method is used to iteratively calculate and solve the velocity, acceleration, displacement and jerk of the shell armature loaded with the bird after passing through the current primary drive coil; Step 4: Use the jerk determination formula to determine the stability of the bird's body deformation during the current first-stage launch process; Step 5: Determine whether the armature displacement of the shell loaded with the bird body meets the requirements. If not, continue to iterate at the current level; if so, execute step 6; Step 6: Reset the drive coil current, the cartridge armature coil current, the mutual inductance between the cartridge armature coil and the drive coil, and the mutual inductance gradient to 0. Repeat step 3 to perform the next level electromagnetic coil launch iterative calculation and solve to obtain the displacement, velocity, acceleration, and jerk of the cartridge armature loaded with the bird after passing through the next level coil. Step 7: Repeat steps 4-6 until the prediction model reaches the preset muzzle velocity requirement; Step 8: Output the final acceleration, displacement, velocity, and bird jerk curve of the cartridge armature loaded with the bird body after the multi-stage electromagnetic coil is fired.

2. The method for rapidly predicting the stability of a bird launched by a multi-stage electromagnetic coil as claimed in claim 1, characterized in that: The step 1 is specifically as follows: Step 1.1: Set the bird's launch velocity; Step 1.2: Set the electrical parameters and structural parameters of the multi-stage electromagnetic coil transmitter; the electrical parameters include: the self-inductance of the drive coil circuit L d , drive coil circuit resistance R d , drive coil circuit discharge capacitance C, drive coil circuit discharge voltage value U d ; Structural parameters include: drive coil loop radius r d 、Radius r of the armature coil of the shell loaded with bird body p , total mass of bird body and armature m p , the distance between the middle position of two adjacent driving coils and the initial emission position; Step 1.3: Divide the armature coil of the shell loaded with the bird into n equal parts according to the current wire method. The self-inductance of the armature coil loop of the jth shell is L pj , the resistance of the armature coil circuit of the jth cartridge case is R pj The mutual inductance between the jth cartridge armature coil and the drive coil is M dpj , j = 1, 2, ···, n; Step 1.4: Set the total prediction time T and the time step Δt, and the number of cycles is i = T / Δt; Step 1.5: Set the initial drive coil current I at time t = 0 d , cartridge armature coil current I p The electromagnetic force F on the shell armature loaded with the bird body, the velocity v of the shell armature loaded with the bird body, the acceleration a, the displacement s, and the jerk β of the bird body are all zero.

3. The method for rapidly predicting the stability of a bird launched by a multi-stage electromagnetic coil as claimed in claim 2, characterized in that: The step 2 is specifically as follows: Step 2.1: Based on the muzzle velocity requirements, structural parameters, and electrical parameters, a prediction model for the multi-stage electromagnetic coil launcher is established. The prediction model includes an equivalent circuit model for the drive coil and an equivalent circuit model for the armature coil of the cartridge case loaded with the bird. The driving coil equivalent circuit model includes: A driving coil discharge switch, a driving coil energy storage capacitor, a driving coil loop resistor, a driving coil loop self-inductance, and a diode; the driving coil loop self-inductance and the driving coil loop resistor are connected in series and then in parallel with the diode, and then connected in series with the driving coil discharge switch and the driving coil energy storage capacitor in sequence to form a closed loop; the driving coil loop resistor includes: capacitor resistance, discharge switch resistance, line resistance, and driving coil resistance; the driving coil loop self-inductance includes: capacitor self-inductance, discharge switch self-inductance, line self-inductance, and driving coil self-inductance; The equivalent circuit model of the armature coil of the loaded bird body includes n equivalent circuits of the armature coil of the cartridge case, wherein each circuit of the armature coil of the cartridge case is a closed circuit formed by connecting the resistance of the armature coil of the cartridge case and the self-inductance of the armature coil of the cartridge case in series; the resistance of the armature coil of the cartridge case includes the line resistance and the resistance of the armature coil of the cartridge case; the self-inductance of the armature coil of the cartridge case includes the line resistance and the self-inductance of the armature coil of the cartridge case; When the drive coil discharge switch is closed, the drive coil energy storage capacitor begins to discharge, the drive coil circuit generates current, and then generates an induced magnetic field. The induced magnetic field causes the armature coil circuits of each cartridge to generate induced currents. The induced currents are subjected to electromagnetic force in the induced magnetic field, causing the cartridge armature to move and be launched. Step 2.2: Ensure that the damping coefficient of the drive coil circuit is in an overdamped state: Where ζ is the damping coefficient of the drive coil loop.

4. The method for rapidly predicting the shape stability of a bird launched by a multi-stage electromagnetic coil as claimed in claim 2, characterized in that: The step 3 is specifically as follows: Step 3.1: Calculate the mutual inductance and mutual inductance gradient between the armature coil of each loaded bird and the current primary drive coil at the current time t based on the following equation: Among them, M dpj is the mutual inductance between the armature coil of the jth cartridge case and the current primary drive coil; is the mutual inductance gradient between the jth cartridge armature coil and the current first-level drive coil; μ is the vacuum magnetic permeability, z j K(k j ) and E(k j ) are the first and second elliptic integral formulas, respectively, θ is the amplitude of the elliptic integral; k j is the independent variable of the elliptic integral; Step 3.2: Calculate the current derivative of the driving coil at the current time t based on the above known conditions and the derivative of the current in the armature coil of each loaded bird The calculation is as follows: According to Kirchhoff's voltage law, the following equivalent circuit equation is constructed for the equivalent circuit of the driving coil; According to Kirchhoff's voltage law, the following equivalent circuit equation is constructed for the equivalent circuit of the armature coil of each loaded bird body; Among them, I d (t) is the driving coil current at time t, I pj (t) is the armature coil current of the jth cartridge case at time t; Substitute the known conditions into the above two equivalent circuit equations to calculate the current derivative of the drive coil and the current derivative of the armature coil of each cartridge case loaded with bird body; Step 3.3: Calculate the driving coil current I at time t' based on the two current derivatives solved in step 3.2 d (t') and the armature coil current I of each loaded bird shell pj (t'): t'=t+Δt Step 3.4: Calculate the electromagnetic force F on the armature of each loaded bird shell at time t' based on the two currents solved in step 3.

3. j (t'): Then calculate the electromagnetic force F(t') on the shell armature loaded with the bird at time t': Step 3.5: Calculate the acceleration a(t') of the cartridge case armature loaded with the bird at time t' based on the electromagnetic force calculated in step 3.4: Step 3.6: Calculate the velocity v(t') of the cartridge case armature at time t': v(t')=v(t)+a(t')Δt Where v(t) is the velocity of the cartridge armature loaded with the bird at time t; Step 3.7: Calculate the displacement s(t') of the cartridge case armature at time t': s(t')=s(t)+v(t')Δt Where s(t) is the displacement of the cartridge armature of the loaded bird at time t; Step 3.8: Calculate the bird's jerk β(t') at time t': Step 3.9: Repeat steps 3.1-3.8 until the bird's displacement satisfies the requirement that the cartridge case armature loaded with the bird is located in the middle of the two-stage drive coil. The time curves of the bird's displacement, velocity, acceleration, and jerk corresponding to the first-stage coil can be obtained.

5. The method for rapidly predicting the stability of a bird launched by a multi-stage electromagnetic coil as claimed in claim 1, characterized in that: The step 4 is specifically as follows: Step 4.1: Select the maximum absolute value of jerk |β(max)| during the current first-stage launch process and establish the following jerk determination formula: Among them, α0 is the launch experience control proportional coefficient, which is between 0.85 and 1.

15. β0 is the jerk reference value related to the high-g acceleration crushing or other bird material damage that may occur during bird launch. It is determined by performing a Hopkinson pressure bar test on the relevant materials of the bird, and represents the ability of the material constituting the bird to maintain its morphological stability after the influence of the alternating stress generated by the external force. Step 4.2: If λ≤1, it means the bird's deformation is within an acceptable range and there is no damage, crushing, or cracking. You can proceed to the next step. Step 4.3: If λ>1, it means that the bird body has been damaged by irresistible external forces, and it is inevitable that it will be damaged or crushed, making it difficult to maintain its shape stability. The iteration is terminated and the process returns to step 1 to adjust the structural and electrical parameters.

6. The method for rapidly predicting the stability of a bird launched by a multi-stage electromagnetic coil as claimed in claim 1, characterized in that: The step 5 is specifically as follows: According to the iterative drive coil level of the current bird-loading shell armature, determine whether the displacement of the bird-loading shell armature meets the requirements: If s(t)<x m , then the requirements are not met, and the iteration continues at the current level; if s(t)≥x m , then the requirements are met, then go to step 6; Among them, x m is the distance between the middle position of the mth and m+1th driving coils and the initial emission position.

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