An underwater high-speed projectile configuration device based on electromagnetic coil ejection

Abstract

The present invention discloses an underwater high-speed projectile configuration device based on electromagnetic coil ejection, comprising a sabot, an armature, a base support, a supporting iron sheet, a tail, and a warhead, to address the technical issues of underwater electromagnetic coil launch testing. The present invention utilizes sub-caliber launch technology, with a supercavitating projectile consisting of a tungsten warhead and an aluminum tail threaded together as the sub-caliber core, secured within the electromagnetic projectile by a nylon sabot and a base support. The electromagnetic projectile shell is formed by a nylon sabot and an aluminum armature threaded together, with an outer diameter matching the inner diameter of the launcher. The base support, mounted at the bottom of the armature, also serves to accelerate the sub-caliber core. The underwater high-speed projectile configuration of the present invention not only meets the launch requirements of underwater multi-stage electromagnetic induction coil guns, but also achieves supercavitating drag reduction during the projectile's navigation process in the water, thereby increasing the initial velocity and range of underwater launches.

Description

Technical Field

[0001] The invention relates to the technical field of underwater electromagnetic induction coil gun launching, in particular to an underwater high-speed projectile configuration device based on electromagnetic coil ejection. Background Art

[0002] Electromagnetic launch offers significant advantages, including high thrust, low launch noise, good concealment, and precise energy control. Using electromagnetic coil launchers for underwater projectile launch holds broad military application prospects. The launch principle of electromagnetic projectiles is as follows: a projectile passes through a pulsed electromagnetic field, where it is accelerated by the Lorentz force and ejected from the barrel. Furthermore, the development of supercavitation technology has significantly increased underwater speeds, making it possible to launch projectiles underwater at low drag and high initial velocity.

[0003] Currently, the design of high-speed projectile configurations for underwater launch focuses on two aspects: one is the air curtain projectile for underwater air curtain launch, which can guide the exhaust gas behind the projectile through internal channels to the front of the projectile, displacing the water column and reducing launch resistance. The other is the ventilated supercavitating projectile, which uses ventilation to assist in the formation of supercavitation and reduce the drag encountered by the projectile during navigation. However, neither of these projectiles can meet the electromagnetic launch requirements of sub-caliber supercavitating projectiles underwater.

[0004] Research on electromagnetic projectiles primarily consists of an armature and a projectile. Their launch velocity is primarily limited by their weight and the current flowing through the armature. A larger metal conductor area increases the maximum conduction current, but also increases the projectile's mass. When designing the armature's thickness, it's important to consider whether its strength meets the requirements for electromagnetic thrust and ablation during launch. Currently, research on coil-type electromagnetic catapult projectiles primarily focuses on land-based launch scenarios, while research on underwater launch environments remains largely unexplored. Summary of the Invention

[0005] The purpose of the present invention is to provide an underwater high-speed projectile configuration device based on electromagnetic coil ejection, which can be used for underwater electromagnetic coil launcher projectile design. At the same time, it can form supercavitation during navigation in the water to continuously reduce drag, thereby achieving the goals of high initial velocity launch and long-distance navigation of underwater electromagnetic launch projectiles.

[0006] The technical solutions for achieving the purpose of the present invention are:

[0007] An underwater high-speed projectile configuration device based on electromagnetic coil ejection includes a sabot, an armature, a base support, a support iron sheet, a tail, and a projectile. During the acceleration process in the projectile chamber, since the diameter of the projectile core is smaller than the caliber of the electromagnetic coil launcher, a sub-caliber launch technology is required. That is, the projectile is placed in a matching sabot for propulsion and launch. The sabot and base support form the support for the projectile core in the sub-caliber launcher, wherein:

[0008] The sabot is cylindrical in shape, with stepped holes and straight holes provided inside, the straight holes being fitted with the bullet through a gap, wherein the straight holes are used to support the core of the supercavitation projectile, and the evenly distributed stepped holes are used to keep the interior of the projectile connected to the external flow field during the firing process, thereby reducing the resistance encountered by the projectile during acceleration due to compression of the fluid in front, and a boss is provided at the rear end of the sabot to provide an external thread for threaded connection with the armature (2);

[0009] The armature is in the form of a cylindrical shell with an annular support cone at the bottom. The inner wall of the cone and the bottom support are fixedly connected by screws.

[0010] The base support is cylindrical in shape, with straight holes evenly distributed inside and a circular groove at the center of the front end. The support iron sheet is fixed to the center of the circular groove by an interference fit. The support iron sheet installed at the center of the base support can increase the contact area and reduce the pressure during the acceleration of the projectile core; the straight holes on the support and base support are connected to the external flow field;

[0011] The front end of the tail and the warhead are connected by a stepped thread to form a core, and the rear end of the tail rests in the circular groove at the front end of the supporting iron sheet. During the launching process, the supercavitating projectile composed of the tail and the warhead can be separated after being pushed and accelerated to complete the underwater strike mission.

[0012] Furthermore, the ratio of the core length to the length of the assembly of the external sabot and armature is 4:3, the diameter of the internal sub-caliber projectile is determined by the damage index requirements of the supercavitating projectile, the diameter of the external sabot and armature assembly is consistent with the inner diameter of the electromagnetic coil launcher, and the tolerance design is based on the convenience of loading.

[0013] Furthermore, the ratio of the diameter of the supporting iron sheet to the diameter of the bullet tail is 2:1.

[0014] Furthermore, six straight holes are evenly distributed on the cartridge case, and the ratio of the hole diameter to the cartridge case diameter is 1:8.

[0015] Furthermore, four straight holes are evenly distributed on the bullet base support, and the ratio of the hole diameter to the bullet base support diameter is 1:12.

[0016] Furthermore, in order to make the acceleration process in the launch tube smooth, reduce resistance and facilitate loading, a 3mm chamfer is set at the front end of the cartridge case.

[0017] Furthermore, considering the strength requirements of the launch process, the armature thickness is set to 5mm after simulation calculation and experimental verification.

[0018] Furthermore, in order to reduce the overall weight of the projectile, the front and rear sides of the support and the bottom surface of the armature are cut without affecting the supporting strength of the core.

[0019] Furthermore, the bullet head is made of tungsten alloy and the tail is made of 7A04 aluminum alloy.

[0020] Furthermore, in order to reduce weight, the support and base support are made of PEEK nylon. In order to generate induced current in the pulsed magnetic field and reduce weight at the same time, the armature material is set to aluminum alloy.

[0021] Furthermore, the outer diameters of the sabot and the armature match the inner diameter of the electromagnetic coil launcher.

[0022] Compared with the prior art, the present invention has the following significant advantages: (1) Compared with the common gas-steam underwater launch, the electromagnetic coil catapult has the advantages of good concealment, good controllability, and large thrust. The underwater high-speed projectile configuration device provided by the present invention can be used for the structural design of underwater closed electromagnetic coil projectiles to meet the needs of the complex electromagnetic field environment in the internal ballistic acceleration stage; (2) The underwater electromagnetic launch projectile configuration device provided by the present invention adopts an internal sub-caliber supercavitating projectile as the striking part. During the high-speed navigation stage in the water after the cartridge is separated from the barrel, the supercavitation formed by cavitation can greatly reduce the viscous resistance of the projectile, thereby reducing the resistance and improving the speed retention capability and range of the projectile; (3) The underwater high-speed projectile configuration device provided by the present invention has a simple and reliable structure and does not require a complex control method and mechanical structure to achieve in-bore propulsion acceleration and core separation from the barrel, thereby meeting the requirements of large thrust acceleration in the barrel and low-resistance movement outside the barrel. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram (cross-sectional view) of an underwater high-speed projectile configuration device based on electromagnetic coil ejection according to the present invention.

[0024] Figure 2 This is an axonometric view of an underwater high-speed projectile configuration device based on electromagnetic coil ejection according to the present invention.

[0025] Figure 3 (a) is a top view of an underwater high-speed projectile configuration device based on electromagnetic coil ejection according to the present invention, Figure 3 (b) is a bottom view.

[0026] Figure 4 (a) is the main view of the support. Figure 4 (b) is the right sectional view of the cartridge case.

[0027] Figure 5 (a) is the main view of the missile base support structure. Figure 5 (b) is a right sectional view.

[0028] Figure 6 Schematic diagram of a multi-stage electromagnetic coil launching device.

[0029] Among them, 1--bullet support; 2--armature; 3--bullet base support; 4--support iron sheet; 5--bullet tail; 6--bullet head. DETAILED DESCRIPTION

[0030] The present invention will be further described below with reference to the accompanying drawings.

[0031] An underwater high-speed projectile configuration device based on electromagnetic coil ejection, comprising a sabot, an armature, a base support, a support iron sheet, a tail and a projectile, wherein the sabot is connected to the armature, the base support is mounted at the bottom of the armature, the support iron sheet is mounted at the center of the support iron sheet, the front end of the tail is connected to the projectile, and the support iron sheet abuts against the rear end of the tail;

[0032] During the projectile's acceleration, the core diameter is smaller than the caliber of the electromagnetic coil launcher, requiring sub-caliber launch technology. This involves placing the projectile into a suitable sabot for propulsion and launch. The sabot and base support form the core support in the sub-caliber launcher.

[0033] The supercavitating projectile, composed of the tail and warhead, serves as a sub-caliber core, and uses stepped threads for assembly to enhance connection strength. The core design meets the requirements for supercavitating projectile navigation. The nose cavitator induces a cavitation phase transition in the surrounding liquid water, forming a supercavity that stably envelops the core. At this point, only the nose of the projectile is subjected to force, while the tail continuously impacts the cavity wall, achieving self-balance through tail-slapping motion. This reduces drag, increases range, and improves the projectile's stability. In order to ensure that the projectile can achieve tail-beating motion in the supercavitation, the aspect ratio and center of mass position of the projectile core need to be designed and numerically verified. The specific requirements are as follows: (1) Projectile core aspect ratio design: Use the Logvinovich empirical formula of the supercavitation contour line based on the principle of independent expansion of the cavitation section to predict the supercavitation contour around the projectile launched at a given initial velocity to ensure that the supercavitation generated by the head cavitator can completely wrap the shoulder and tail of the projectile; (2) Projectile core center of mass position design: By adjusting the length and material density of the projectile and tail, the center of mass position of the supercavitation projectile is located at an appropriate position in the front half of the projectile length, so that the projectile rotates around the center of mass due to water pressure. When the destabilizing torque occurs, the tail of the projectile can timely touch the cavity wall or water phase to generate an instantaneous tail stabilizing torque, so that the projectile will swing periodically when navigating in the cavity, maintain dynamic balance, and achieve stability of movement; the warhead is made of tungsten alloy to ensure the structural strength of the head and ensure that it can effectively destroy the target; the tail of the projectile is made of aluminum alloy, which not only ensures the structural strength but also moves the center of mass of the projectile forward, thereby improving its underwater navigation stability; in addition, the head cavitator adopts a disc-shaped structure, which has the advantages of large cavitation size and high flight stability; the tail of the projectile adopts a cylindrical structure, which has the advantages of high structural strength and low production cost.

[0034] During the launch process, the synchronous discharge of each stage's drive coil generates an induced current (eddy current) within the armature. The eddy current interacts with the magnetic field to generate an electromagnetic force, which continuously accelerates the projectile, thereby propelling the projectile and its internal core forward. Because the final stage's electromagnetic coil is designed in reverse, the armature experiences a deceleration effect, while the internal core is not affected by the deceleration and, due to the reduced friction of the nylon sabot, it separates on its own, sailing the designated distance through the water and achieving the desired damage effect.

[0035] Because electromagnetic projectiles convert electrical energy into kinetic energy during acceleration, factors influencing energy conversion efficiency must be considered when designing electromagnetic projectiles. Numerical simulations show that greater projectile mass increases conversion efficiency. However, excessively large projectile mass cannot meet the initial velocity requirements for long-range underwater navigation of sub-caliber supercavitating projectiles.

[0036] Since the density of water is much greater than that of air, in order to avoid excessive chamber pressure during firing and to prevent water from entering the launcher barrel and interfering with the electromagnetic field, the launch method adopts underwater closed firing, that is, the muzzle is sealed with aluminum foil before firing to avoid the influence of the water medium on the ballistic process during firing.

[0037] In summary, the present invention utilizes sub-caliber launch technology. A supercavitating projectile, composed of a tungsten warhead and an aluminum tail threaded together, serves as the sub-caliber core. This projectile is secured within the electromagnetic projectile via a nylon sabot and a base support. The electromagnetic projectile's outer shell, formed by a nylon sabot and an aluminum armature threaded together, has an outer diameter that matches the inner diameter of the launcher. The base support, mounted at the bottom of the armature, also accelerates the sub-caliber core. This underwater high-speed projectile configuration not only meets the launch requirements of underwater multi-stage electromagnetic induction coil guns, but also achieves supercavitating drag reduction during the projectile's underwater navigation process, thereby increasing the initial velocity and range of underwater launches.

[0038] Example

[0039] Combine Figures 1-6 This embodiment provides an underwater high-speed projectile configuration device based on electromagnetic coil ejection, including a sabot 1, an armature 2, a base support 3, a supporting iron sheet 4, a tail 5 and a warhead 6.

[0040] The sabot 1 is cylindrical with a boss at the rear end. The boss is threaded to assemble with the armature. A straight hole is provided inside to support the projectile core through a clearance fit. Evenly distributed holes are provided around the straight hole, and a chamfer is machined at the front end. The straight hole is used to support the supercavitating projectile core, and the evenly distributed stepped holes are used to maintain communication between the interior of the projectile and the external flow field during the launch process, reducing the resistance encountered by the projectile during acceleration due to the compression of the fluid in front.

[0041] The armature 2 is a cylindrical shell with an annular support cone at the bottom, and is fixed to the bottom support by screws. In order to generate induced current in the pulsed magnetic field and reduce weight, the material is set to aluminum alloy.

[0042] The bottom support 3 is cylindrical in shape, with four straight holes evenly distributed inside to keep the flow field inside and outside the projectile connected. A circular groove is provided in the center of the front end, and is fixed to the support iron plate 4 by interference fit.

[0043] The core is composed of a tail 5 and a warhead 6 connected by a stepped thread. It is used as a sub-caliber supercavitating core to strike underwater targets. At the same time, in order to reduce the pressure of the projectile body on the bottom support 3 during the acceleration stage in the barrel of the projectile, the bottom of the core is placed against the front end slot of the support iron plate 4 fixed on the bottom support 3.

[0044] In terms of part size ratio design, under the conditions of determining the supercavitating projectile diameter, aspect ratio, and electromagnetic coil launcher inner diameter parameters, the following dimensions and ratio relationships were designed and verified:

[0045] ① In order to ensure that the sabot 1 supports the projectile stably during the propulsion process in the launcher, the length of the projectile inside the sabot and the length of the assembly of the external sabot 1 and armature 2 must be designed to ensure that the center of mass of the supercavitating projectile is located on the support surface of the sabot 1. After 3D modeling and multiple tests, it is proved that in the application scenario of this underwater electromagnetic catapult high-speed projectile, when the ratio of the projectile (core) length to the assembly length of the external sabot 1 and armature 2 is 4:3, the requirements of the supercavitating projectile being stably accelerated and effectively supported by the sabot 1 can be met;

[0046] ② Because the base support 3 is made of relatively low-strength nylon, in order to increase the contact area and reduce the pressure during the acceleration of the projectile, strength calculation and simulation verification of the support surface area and thickness parameters were performed. It was found that a ratio of the diameter of the support iron plate 4 to the internal projectile diameter of 2:1 can meet the strength requirements;

[0047] When performing strength calculations and simulation verification, the compressive strength calculation formula and yield strength formula are used.

[0048] Young's modulus is an indicator of material rigidity. It is the ratio of unit strain under unit stress. Its calculation formula is:

[0049] E=σ / ε

[0050] Where E is Young's modulus, in Pa; σ is stress, in Pa; ε is strain, without unit.

[0051] The formula for calculating compressive strength is:

[0052] σ=F / A

[0053] Among them, F is the force magnitude, unit is N; A is the force area, unit is m2.

[0054] This configuration design uses the following shear yield strength and compression yield strength formulas for verification:

[0055] Shear yield strength formula: τ f =σ f / B

[0056] Compression yield strength formula: σ f =E·ε f

[0057] Among them, τ f , σ f , ε f They represent shear yield strength, stress intensity, and strain intensity, respectively; B and E represent cross-sectional area and modulus.

[0058] ③ To reduce the overall weight of the projectile and minimize air resistance during acceleration, uniformly spaced through-holes are introduced into the larger diameter sabot 1 and base support 3, without compromising support strength. This allows for communication between the internal and external flow fields of the projectile. Through 3D modeling and fluid-structure interaction simulation, parameters such as the number, location, and diameter of the through-holes were designed and verified. The specific design dimensions are as follows: sabot 1 features six uniformly spaced through-holes, with a diameter-to-sabot ratio of 1:8; base support 3 features four uniformly spaced through-holes, with a diameter-to-base support ratio of 1:12. Simulations and multiple tests confirmed that the through-holes do not affect the launch performance of the electromagnetic projectile, significantly reducing weight.

[0059] Furthermore, based on the Logvinovich empirical formula, the aspect ratio of the supercavitating projectile is designed and verified to ensure that the supercavitation generated by the head cavitator can completely wrap the projectile body. n is the sectional radius of the disk cavitator, then the maximum sectional radius of the supercavitation is R c and the maximum cavitation length L c They are:

[0060] R c =R n C x0 (1+σ)kσ

[0061]

[0062] Where C x0 is the drag coefficient when the cavitation number σ = 0, and C of the disc cavitator x0 The coefficient k is set to 0.83; the coefficient k is related to the size of the cavitation number σ. The smaller the cavitation number, the larger k is. The calculation formula is:

[0063]

[0064] According to the supercavitation independent expansion theory, the supercavitation contour formula is derived:

[0065]

[0066] Where x is the horizontal displacement of the supercavitation contour from the cavitator section, and R(x) is the cavitation radius.

[0067] Furthermore, the field-circuit coupling method and finite element analysis method are applied to the acceleration process of the projectile in the electromagnetic coil launcher, and the electromagnetic field equations of the coil launcher and the external control circuit equations are coupled for solution. At the same time, the thrust exerted on the electromagnetic projectile obtained by the solution is used to perform strength verification on the wall thickness of the armature 2 and the thickness of the base support 3, which are prone to strength failure. The results meet the strength requirements of the in-bore acceleration process and are verified through experiments.

[0068] Furthermore, in order to ensure smooth separation of the electromagnetic projectile sabot 1 from the projectile core, the current direction of the last-stage electromagnetic coil is set to the reverse direction, so that the armature 2 moves to this point to produce a deceleration effect, while the internal projectile is not affected and the speed remains unchanged, and the friction force exerted by the sabot 1 is also small, thereby successfully completing the shelling function before leaving the tube.

[0069] Furthermore, in terms of component material selection, to reduce the total mass of the projectile and increase the initial velocity of the projectile, the material of the sabot 1 and the base support 3 is set to nylon, while meeting the strength requirements. To avoid interference from strong pulsed magnetic fields, considering that the base support material is nylon, a large thrust is required during launch to accelerate the supercavitation projectile inside the projectile, so a support iron plate is designed to be installed on it to reduce local pressure and prevent deformation of the base support. The support iron plate has a circular groove at one end to push the projectile. After the switch is triggered and the circuit is connected, the projectile is in the induced strong pulsed magnetic field. To avoid interference from electromagnetic induction, the support iron plate material is selected from austenitic stainless steel, which has poor electrical and magnetic properties.

[0070] Furthermore, in order to make the acceleration process in the launch tube smooth, reduce resistance and facilitate loading, a 3mm chamfer is set at the front end of the cartridge case.

[0071] Furthermore, considering the strength requirements of the launch process, the armature thickness is set to 5mm after simulation calculation and experimental verification.

[0072] Furthermore, the sub-caliber supercavitating projectile's nose is made of high-strength, high-density tungsten alloy, ensuring structural strength and damage effectiveness. This shifts the core's overall center of gravity forward, ensuring tail-beating motion within the supercavitation while the projectile maintains stability. The core's overall design, including its aspect ratio, meets the requirements for supercavitating projectiles.

[0073] The working process of the underwater high-speed projectile configuration device based on electromagnetic coil ejection provided by the present invention is as follows:

[0074] After the launch process begins, a charger charges the energy storage capacitors of the multi-stage induction coil gun power module. Sequentially, the trigger switches of each stage's drive coil are closed through timing control, causing the energy storage capacitors to discharge, stimulating a pulsed magnetic field in the drive coils. This in turn induces a current in the projectile's armature 2, generating an electromagnetic force that propels the projectile forward and accelerates. When the electromagnetic projectile accelerates to the final coil stage, the current in the final coil is reversed, decelerating the armature 2. The sub-caliber core inside the projectile is not decelerated and separates from the sabot 1. It then penetrates the muzzle seal and enters the water, forming a natural supercavitation bubble. This reduces the viscous drag experienced by the projectile while navigating underwater, effectively improving its velocity retention and range, achieving the desired range and damage effect.

[0075] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, 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. An underwater high-speed projectile configuration device based on electromagnetic coil ejection, characterized by: It comprises a bullet support (1), an armature (2), a bullet base support (3), a supporting iron sheet (4), a bullet tail (5) and a bullet head (6); wherein: The cartridge holder (1) is cylindrical in shape, with a stepped hole and a straight hole provided inside, the straight hole and the bullet (6) are fitted with clearance, and the rear end of the cartridge holder (1) is connected to the armature (2); The armature (2) is in the form of a cylindrical shell, with an annular support cone at the bottom, the inner wall of the cone and the base support (3) are fixedly connected, and the support (1) and the base support (3) form a support for the core of the sub-caliber launcher; The bottom support (3) is cylindrical in shape, has straight holes evenly distributed inside, and a circular groove is provided at the center of the front end. The support iron sheet (4) is fixed to the center of the circular groove by interference fit; the straight holes on the support (1) and the bottom support (3) are connected to the external flow field; The front end of the bullet tail (5) and the bullet head (6) are connected by a stepped thread to form a bullet core. The rear end of the bullet tail (5) is placed in the circular groove at the front end of the supporting iron sheet (4) and is separated from the supporting iron sheet (4) during the process of being launched out of the barrel.

2. The underwater high-speed projectile configuration device based on electromagnetic coil ejection according to claim 1, characterized in that: The ratio of the length of the core to the length of the assembly of the outer support (1) and the armature (2) is 4:

3.

3. The underwater high-speed projectile configuration device based on electromagnetic coil ejection according to claim 1, characterized in that: The ratio of the diameter of the supporting iron sheet (4) to the diameter of the spring tail (5) is 2:

1.

4. The underwater high-speed projectile configuration device based on electromagnetic coil ejection according to claim 1, characterized in that: Six straight holes are evenly distributed on the cartridge holder (1), and the ratio of the hole diameter to the cartridge holder (1) diameter is 1:

8.

5. The underwater high-speed projectile configuration device based on electromagnetic coil ejection according to claim 1, characterized in that: Four straight holes are evenly distributed on the bullet bottom support (3), and the ratio of the hole diameter to the diameter of the bullet bottom support (3) is 1:

12.

6. The underwater high-speed projectile configuration device based on electromagnetic coil ejection according to claim 1, characterized in that: The front end of the spring support (1) is provided with a 3mm chamfer, and the thickness of the armature (2) is set to 5mm.

7. The underwater high-speed projectile configuration device based on electromagnetic coil ejection according to claim 1, characterized in that: The front and rear sides of the spring support (1) and the bottom surface of the armature (2) are subjected to cutting processing.

8. The underwater high-speed projectile configuration device based on electromagnetic coil ejection according to claim 1, characterized in that: The bullet head (6) is made of tungsten alloy, and the tail (5) is made of 7A04 aluminum alloy.

9. The underwater high-speed projectile configuration device based on electromagnetic coil ejection according to claim 8, characterized in that: The cartridge holder (1) and cartridge base support (3) are made of PEEK nylon.

10. An underwater high-speed projectile based on electromagnetic coil ejection according to any one of claims 1 to 9 The configuration device is characterized by: The outer diameters of the support (1) and the armature (2) match the inner diameter of the electromagnetic coil launcher. The rear end of the spring support (1) is provided with an external thread for threaded connection with the armature (2).

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