Lightweight co-cavity casting net catching device

Abstract

The invention relates to a light-weight co-cavity casting net catching device. Comprising an ignition assembly and a net bin assembly which are detachably connected. The net bin assembly comprises a shell, a common cavity cap is arranged in the shell, the net bin assembly further comprises a plurality of casting body pipes detachably connected with the common cavity cap, a traction body is arranged in each casting body pipe, a flexible rope net connected with the traction bodies is located in the shell, a cover plate is arranged at an outlet of the shell in a matched mode, and the cover plate provides a starting pressure threshold value. A high-pressure buffering cavity is formed between the ignition assembly and the common cavity cap, and through the grading design of a first-stage diffusion cavity and a second-stage stagnation cavity, the dynamic pressure of the central axis of the high-pressure buffering cavity is not attenuated, and a flow field enters a complete stagnation area. The device solves the problems that a traditional net capturing device does not share a cavity in net opening and is uneven in coverage, has the advantages of being compact in structure, micro in recoil force, low in incidental damage, high in energy conversion efficiency and the like, supports multi-device joint installation deployment and module rapid replacement, and is particularly suitable for efficient physical interception of unmanned aerial vehicles.

Description

Technical Field

[0001] This invention belongs to the technical field of drone countermeasures, specifically relating to a lightweight concave projectile net capture device. Background Technology

[0002] With the rapid development and widespread application of drone technology, its potential security risks are becoming increasingly prominent, posing a severe challenge to airspace management and the protection of key areas. In particular, drones, characterized by their low altitude, slow speed, and small size, are often used for unauthorized flights, close-in reconnaissance, object dropping, and even malicious attacks due to their low cost, ease of acquisition and control, high maneuverability, and difficulty in being effectively identified and tracked by traditional detection methods. Such activities not only disrupt normal aviation order and social activities but may also directly threaten critical infrastructure, key security targets, and personnel safety. Therefore, developing efficient, reliable, and adaptable counter-drone devices has become an urgent problem to be solved.

[0003] Currently, anti-drone technologies can be mainly divided into two categories: hard-kill and soft-kill. Hard-kill technologies directly damage or capture targets through physical means such as missile interception and laser destruction; soft-kill technologies mainly disable their normal operation by interfering with communication and navigation links. However, each technology has certain limitations, so the overall performance of current anti-drone devices still needs further improvement.

[0004] In the prior art, a patent entitled "A Net-Catching Unmanned Aerial Vehicle Countermeasure Device" (CN119845096 A) discloses a net-catching unmanned aerial vehicle countermeasure device, including a carrier drone and a net-catching device installed under its body. The net-catching device mainly consists of a connecting mechanism, a self-detaching mechanism, and a capture net. The connecting mechanism includes a connecting ring and a retractable rope threaded through the edge of the capture net. The self-detaching mechanism uses magnetic assemblies at both ends of a support rod to attract the capture net and keep it deployed. This device achieves the deployment and suspension of the capture net through magnetic attraction. After the target drone is caught, the torque generated by the rotation of the target drone's propeller causes the magnet to detach, and the capture net tightens along the retractable rope under the action of gravity, thereby completing the capture and allowing it to be smoothly carried and recovered by the carrier drone. Although this prior art achieves smooth recovery after capture through magnetic deployment and gravity-based net retrieval, its detachment mechanism relies on the torque triggering of the target drone's own rotor, resulting in insufficient adaptability to high-speed or highly maneuverable targets. Furthermore, the entire device places high demands on the load distribution and flight stability control of the carrier drone. Patent CN221425497 U, entitled "A Capture Device for Intercepting Drones," discloses a capture device for intercepting drones, mainly comprising a square cylindrical shell and an internal ejection and triggering assembly. The ejection assembly includes an ejection rod, an elastic element, and an ejection tube, with a capture net connected to the top of the ejection rod. The triggering assembly includes a cutting component and a driving component, controlling the cutting action via a traction rope to release the compressed ejection rod, thereby ejecting the capture net. This prior art employs a mechanical ejection method, whose ejection distance and net-opening effect are limited by the spring's performance, making it insufficiently applicable to specific scenarios. Summary of the Invention

[0005] The purpose of this invention is to provide a device for intercepting drones, which is compact, lightweight, safe to use, and inexpensive to manufacture and operate. It can rapidly deploy a flexible rope net by ejecting multiple traction bodies with high-pressure gas, achieving efficient physical interception of "low, slow, and small" drones.

[0006] The technical solution to achieve the purpose of this invention is: a lightweight common cavity projectile net trapping device, comprising a detachably connected ignition assembly and a net bin assembly;

[0007] The net enclosure assembly includes a shell, a common cavity cap inside the shell, and multiple projectile tubes detachably connected to the common cavity cap. Each projectile tube contains a traction body, and a flexible rope net connected to the traction body is located inside the shell. A cover plate is provided at the shell outlet, and the cover plate provides an initiation pressure threshold.

[0008] A high-pressure buffer chamber is formed between the ignition assembly and the common cavity cap. The high-pressure buffer chamber adopts a graded design of a first-stage diffuser chamber and a second-stage stagnation chamber, so that the dynamic pressure of the central axis has no attenuation and the flow field enters the completely stagnation zone, ensuring that the gas pressure acts on all traction bodies instantaneously, uniformly, and in a common cavity manner.

[0009] One application of the above-mentioned device is for countering unmanned aerial vehicles (UAVs), specifically:

[0010] The device is mounted on the carrier platform; in standby mode, the ignition assembly and the net assembly remain connected, the flexible rope net is folded and stored inside the outer shell, the traction body is placed in the projectile tube, and the cover plate and the outer shell are tightly fitted to form a seal, ensuring that the device has a set start-up threshold.

[0011] Once the carrier platform's detection system identifies and locks onto the target UAV, it sends a trigger command to the device. The black powder in the ignition assembly is electrically ignited, instantly generating high-temperature, high-pressure gas in the propellant chamber. After the gas destroys the propellant cap, it enters the gas chamber of the common cavity cap, causing the internal pressure of the chamber to rise rapidly. When the pressure exceeds the activation threshold formed by the tight fit between the cap and the outer shell, the six towing bodies, propelled by the common cavity of the high-pressure gas, fly out at high speed along the preset direction of their respective launch tubes.

[0012] Each towing body is connected to the corresponding corner of the flexible rope net at its tail. As the towing body flies away from the shell, it pulls the flexible rope net open, forming a hexagonal interception net in the air to entangle and capture the target drone.

[0013] After the interception is completed, the independent modular network warehouse component is replaced to restore the device to standby status and enable reuse.

[0014] Compared with the prior art, the significant advantages of this invention are:

[0015] This invention employs a small amount of black powder as a controllable instantaneous power source, achieving an optimal balance between energy release and recoil through powder dosage control. The transient high-pressure gas generated in the chamber under electrical triggering provides the system with a high energy density thrust far exceeding that of traditional springs. At the same time, its low recoil characteristics ensure minimal interference with the flight attitude of the mounted platform, significantly improving launch safety, platform stability, and applicability to urban environments.

[0016] In this invention, the power source consisting of the medicine chamber 4, the medicine cap 5, and the black powder can be replaced with a gas launcher. Compared to black powder launch, gas launch produces no flame, no smoke, and no noise, improving launch concealment, safety, and environmental adaptability, making it particularly suitable for specific occasions such as cities and densely populated areas.

[0017] This invention, through parameterized design of the inlet area and outlet flux area of ​​the medicine chamber, locks the system flow coefficient at a certain value. The optimal range utilizes a certain intake redundancy to effectively cover the volume expansion effect of the traction body at the moment of exiting the pipe, ensuring that the device is in an "overpressure charging" state and maintains "constant pressure injection", thus ensuring that the lower end obtains a stable peak pressure instantly.

[0018] This invention designs a common cavity cap 8 structure, so that the tops of the six traction bodies 11 are all located in a completely connected, sealed, high-pressure chamber. Through the graded design of the first-stage diffuser chamber and the second-stage stagnation chamber, the dynamic pressure of the central axis is almost unaffected by the sudden expansion pipe flow pressure recovery theory. The flow field enters the completely stagnation zone, ensuring that the gas pressure can act on all traction bodies 11 instantaneously, uniformly, and in a common cavity. This solves the problem of non-common cavity operation caused by pressure difference in multi-tube projectile devices, and ensures that the flexible rope net 9 unfolds regularly, quickly, and completely.

[0019] In this invention, six projectile tubes 10 are fixed to the common cavity cap 8 by threaded connection at a preset angle, thereby making them evenly and symmetrically distributed along the circumference. Driven by the common cavity gas, more than 95% of the gunpowder energy is retained for forward propulsion, while more than 20% of the equivalent thrust is converted into radial expansion force, enabling the six traction bodies 11 to drive the flexible rope net 9 to rapidly open in a very short time to form a stable "net" configuration, which has high capture and coverage capabilities and adaptability to time and space windows.

[0020] In this invention, all six ends of the flexible rope net 9 are connected to the corresponding traction body 11 by knotting the ropes. This connection method has a simple structure and extremely high mechanical reliability. Combined with the "quasi-rigid" physical boundary of the variable wall thickness design (the actual strain rate always satisfies the specified condition), the connection is effective. (with a rigid threshold), it can effectively resist impact during the transient ejection process driven by high-pressure gas, ensuring that the traction body and the rope net do not accidentally fall off.

[0021] In this invention, the outlet of the flexible rope net 9 adopts a tight-fitting sealing design between the cover plate 12 and the outer shell 7, setting a mechanical start-up pressure threshold for the device. This mechanism, combined with a flange-type axial hard limit design based on the constant volume locking principle, effectively prevents malfunctions and ensures pressure consistency. The traction body 11 is only released when the gas pressure is sufficient, significantly improving the consistency of the system.

[0022] The invention has a simple and reliable structure. The wall thickness designed using the thick-walled cylinder theory achieves lightweighting while ensuring a certain overall system energy conversion efficiency. Furthermore, both the mesh bin component 2 and the ignition component 1 are independent sealed modules, which can be quickly replaced as a whole, reducing energy costs and maintenance difficulty, and enabling the device to operate continuously at low cost in special environments.

[0023] Based on its inherent modularity and shared cavity advantages, this invention can easily achieve multi-unit integration. Through the symmetrical arrangement of dual or multiple networks and shared cavity launch, the interception area and acquisition probability are improved, possessing the potential for multi-target cooperative interception. The system has strong scalability and is suitable for dealing with cluster targets in high-threat scenarios.

[0024] The interception mechanism of this invention is a physical interception, with no electromagnetic interference and will not affect surrounding electronic equipment. The flexible rope net 9 captures the target drone by entangling rather than physically destroying it, reducing collateral damage to the target drone and its crash site, making it particularly suitable for sensitive environments such as cities, airports, and important facilities.

[0025] Compared to some countermeasures, this invention features a simpler device structure, controllable material costs, and a relatively mature manufacturing process, resulting in a significant cost advantage. Its lightweight design also reduces the load requirements and energy consumption of the carrier platform, demonstrating outstanding economic efficiency and cost-effectiveness. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall structure of the common cavity projectile net trapping device of the present invention.

[0027] Figure 2 This is a schematic diagram of the ignition assembly of the present invention; wherein (a) is a cross-sectional view and (b) is a three-dimensional view.

[0028] Figure 3 This is a schematic diagram of the network warehouse component structure of the present invention; wherein (a) is an exploded view and (b) is a cross-sectional view.

[0029] Figure 4 This is a schematic diagram of the high-pressure buffer chamber structure of the present invention.

[0030] Figure 5 This is a schematic diagram of the traction body and flexible rope net structure of the present invention.

[0031] Explanation of reference numerals in the attached figures:

[0032] 1-Ignition assembly, 2-Net compartment assembly, 3-Pressure pad, 4-Propellant chamber, 5-Propellant cap, 6-Connector, 7-Outer shell, 8-Common cavity cap, 9-Flexible rope net, 10-Projectile tube, 11-Traction body, 12-Cover plate. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to the accompanying drawings.

[0034] As shown in Figures 1-4, the lightweight common cavity projectile net capture device comprises two main modules: an ignition assembly 1 and a net bin assembly 2.

[0035] The ignition assembly 1 consists of a pressure pad 3, a propellant chamber 4, a propellant cap 5, and a connector 6 from top to bottom. The propellant cap 5 and the connector 6 are made of lightweight aluminum alloy.

[0036] Both the inner wall of the clamping pad 3 and the upper outer wall of the connector 6 are threaded, and the two are connected by threads. The upper inner wall of the clamping pad 3 contacts the upper boss of the powder chamber 4, and the upper boss of the connector 6 contacts the lower boss in the powder chamber 4, thereby limiting the position of the powder chamber 4. The lower inner wall of the powder chamber 4 is threaded, and the upper outer wall of the powder cap 5 is threaded, and the two are connected by threads to fix the powder cap 5 on the powder chamber 4, and black powder is loaded inside the powder chamber 4 and the powder cap 5.

[0037] The black powder inside the ignition chamber 4 and the cap 5 is ignited. After the black powder is ignited, it generates high-temperature and high-pressure gas, which destroys the cap 5 and provides instantaneous thrust to the traction body 11.

[0038] The lower outer wall of connector 6 is threaded, and the upper inner wall of common cavity cap 8 is threaded. The two are connected by threads, which simultaneously achieves positioning and sealing.

[0039] The net enclosure component 2, from top to bottom, includes an outer shell 7, a common cavity cap 8, a flexible rope net 9, a projectile tube 10, a traction body 11, and a cover plate 12. Among them, the flexible rope net 9 is made of Dyneema material, the projectile tube 10 is made of high-quality carbon steel, and the traction body 11 is made of tungsten alloy.

[0040] The inner wall of the upper end of the outer shell 7 is engraved with threads, and the outer wall of the upper end of the common cavity cap 8 is engraved with threads. The two are connected by threads and simultaneously complete the limiting function.

[0041] The common cavity cap 8 contains six threaded holes at preset angles, evenly distributed. The upper outer walls of the six projectile tubes 10 are threaded, and the two are threadedly connected, simultaneously achieving a limiting effect. Six traction bodies 11 are respectively placed inside the six projectile tubes 10. The tail of each traction body 11 is connected to a flexible rope net 9, which is placed inside the outer casing 7. The cover plate 12 fits tightly with the outer casing 7, ensuring good sealing while also providing a starting threshold to ensure that the six traction bodies 11 are launched from the common cavity.

[0042] The high-pressure buffer chamber consists of a propellant cap 5, a connector 6, and a common cavity cap 8. The maximum propellant charge capacity of the ignition assembly 1 is known to be mg, and the inner diameter of the projectile tube is r mm.

[0043] Total output flux area A of the high-pressure buffer chamber out for

[0044] (1)

[0045] In the formula: N is the number of exits, and r is the radius of each projectile tube.

[0046] The flow coefficient is defined as the ratio of the total input flux area to the total output flux area; this invention uses the flow coefficient... The range of values ​​for is limited to:

[0047] (2)

[0048] According to the dynamic compensation principle, in the initial few milliseconds (t < 1 ms) of launch initiation, the tractor moves forward within the barrel, causing a rapid increase in the effective volume V(t) within the barrel. This volume expansion effect is equivalent to the "dynamic leakage" of gas. If the intake flow rate is less than 1.2, it will be unable to cover this volumetric growth rate, leading to increased intracavity pressure. The pressure begins to decrease (drop) before the traction body exits the pipe. (Setting) A flow coefficient of ≥1.20 provides approximately 20% intake redundancy, ensuring that the intake velocity is always faster than the volume expansion velocity, maintaining "constant pressure injection." Based on structural safety considerations, this is limited by the mechanical strength of the connector (usually a threaded connection). If the flow coefficient is too high, the corresponding inlet orifice diameter will increase significantly, resulting in excessively thin solid wall thickness at the thread root. Under extreme high-pressure impact, root shear fracture is highly likely to occur. Beyond 1.35, the fluid charging efficiency exhibits diminishing marginal returns, not only failing to increase pressure but also increasing ineffective dead volume.

[0049] Setting value of the inlet area of ​​the high-pressure buffer chamber for

[0050] (3)

[0051] Therefore, the diameter of the medicine chamber 4 for

[0052] (4)

[0053] Utilizing the theory of sudden diffusion pipe flow in fluid mechanics. Fluid flows from... Upon entering the chamber, a sudden expansion occurs. To maximize the efficiency of converting kinetic energy into static pressure, it is necessary to find a pressure recovery coefficient. The maximum point.

[0054] The derivation of this numerical range is based on derivative analysis of Borda-Carnot losses and the optimal diffusion ratio. According to the principle of energy conservation in fluid mechanics, a Bernoulli equation including energy loss terms is established between the inlet section and the high-pressure buffer chamber section:

[0055] (5)

[0056] In the formula: This refers to the static pressure at the inlet of the injection channel. To restore the static pressure within the high-pressure buffer chamber. The average velocity of the fluid injected into the channel. The average velocity of the fluid within the high-pressure buffer chamber. For gas density, The mechanical energy loss caused by sudden expansion is defined by the "Boda-Carnot formula":

[0057] (6)

[0058] Combining the above two equations, the pressure recovery amount during the conversion of kinetic energy into static pressure can be derived.

[0059] (7)

[0060] This leads to the pressure recovery coefficient for the conversion of kinetic energy into static pressure. Compared with area ratio The relationship is:

[0061] (8)

[0062] In order to obtain The maximum value of, for Perform first derivative analysis:

[0063] (9)

[0064] Setting the derivative to zero, we get =0.5, which is the optimal expansion ratio. .

[0065] Therefore, based on the set value of the inlet area of ​​the high-pressure buffer chamber, the optimal cross-sectional area of ​​the first-stage diffuser in the high-pressure buffer chamber is... for

[0066] (10)

[0067] The corresponding high-pressure buffer chamber's first-stage diffuser inner diameter for

[0068] (11)

[0069] Axial distance of the first-stage chamber of the high-pressure buffer chamber The setting principle is: using the turbulent jet theory, the high-speed fluid injected from the drug chamber is made to complete sufficient lateral expansion within this distance until the fluid boundary is completely attached to the side wall of the first-stage chamber.

[0070] This axial distance The following conditions must be met: If the height is too short, the fluid will not fill the first-stage space before entering the next stage, causing the first-stage diffusion function to fail; if the height is too long, it will generate excessive ineffective volume and increase frictional losses along the flow path. To ensure the jet core accurately expands to the wall, the axial distance of the first-stage chamber... Determined according to Abramovich's expansion angle formula, that is:

[0071] (12)

[0072] In the formula: The semi-expansion angle of the jet is an empirical value for confined sudden expansion turbulence. .

[0073] Using the "total expansion ratio stagnation threshold" in jet impact dynamics, the minimum cross-sectional area required to eliminate the peak dynamic pressure at the center is determined. After kinetic energy recovery (first stage) is completed, the cross-section needs to be further expanded to construct a wide "static pressure pool". According to the attenuation law of the free jet centerline velocity, when the total flow area expansion ratio... When the pressure reaches 3.0, the dynamic pressure at the central axis decreases by more than 99%, and the flow field enters the completely stagnant zone. At this time, the consistency error of the inlet pressure of each nozzle is <1%.

[0074] (13)

[0075] (14)

[0076] Therefore, the diameter of the second stage of the high-pressure buffer chamber for

[0077] (15)

[0078] Anti-blocking criteria based on the "continuity equation" to prevent... If the height is too small, the lateral air supply area will be smaller than the downstream load area (i.e., secondary throttling will occur), so a minimum physical height needs to be set. Derivation formula:

[0079] (16)

[0080] In the formula: , To prevent blockage and ensure safety.

[0081] (17)

[0082] Under the premise of meeting gas supply requirements, high Each 1mm increase significantly increases the ineffective "dead volume". If Further increases in dead volume will lead to increased peak pressure. Exponential decay. Establish a volumetric-pressure sensitivity equation based on the adiabatic state equation. Differential form:

[0083] (18)

[0084] In the formula: The gas insulation index is set to 1.3. For dead volume increment, , Design the total free volume for this system. For a system with a charge of mg:

[0085] (19)

[0086] The pressure fluctuation threshold should not be lower than 10% of the peak pressure, i.e.

[0087] (20)

[0088] From formulas 18, 19, 20, and 21, we can see that... satisfy:

[0089] (twenty one)

[0090] By utilizing the potential energy core theory in jet dynamics, the airflow is ensured to impact the flat bottom with maximum kinetic energy. This is to achieve maximum stagnant pressure. Impact distance It must be located at the potential energy core length where the jet velocity has not decayed. Within.

[0091] (twenty two)

[0092] (twenty three)

[0093] Furthermore, to ensure the efficient conversion of gas energy into the work output of the traction engine, it is necessary to cut off the energy absorption by the elastic deformation of the chamber wall. Therefore, this invention sets the safety boundary condition of the high-pressure buffer chamber under extreme high-pressure impact as a "quasi-rigid" state, that is, limiting the maximum allowable strain rate of the chamber wall. Using the Latin American theory of thick-walled cylinders in solid mechanics, the radial displacement of a thick-walled cylinder under internal pressure is calculated as follows:

[0094] (twenty four)

[0095] In the formula, This refers to the radial displacement of the inner wall of the high-pressure buffer chamber. Design peak pressure within the cavity, The inner radius of the high-pressure buffer chamber; The outer radius of the high-pressure buffer chamber; The elastic modulus of the cavity material; Let be the Poisson's ratio of the material.

[0096] Combined with the definition of strain rate To meet By reverse-engineering the rigid requirements, the minimum outer radius required for the high-pressure buffer chamber can be obtained. The calculation model is as follows:

[0097] (25)

[0098] In a high-pressure buffer chamber containing multiple stepped inner diameters, let its maximum inner radius be... Under the same peak pressure, the section containing the maximum inner radius is the most dangerous section with the weakest resistance to radial expansion. Substituting into the above model, the minimum outer radius for global safety can be obtained. Based on this envelope derivation, this invention designs the exterior of the high-pressure buffer chamber as a uniform-diameter cylindrical structure, and uniformly sets its effective pressure-bearing outer diameter as [missing value]. And satisfy The design follows the principle of equal-diameter cylindrical envelope design, using the cross-section with the largest radius in the chamber (i.e., the weakest and most dangerous cross-section against radial expansion) as the benchmark to determine the global outer radius. By strictly defining the mechanical boundaries, the possibility of elastic deformation and energy absorption in all stepped chambers under ultra-high pressure impact is eliminated, ensuring that almost all of the gas energy is converted into mechanical work.

[0099] Let the total thrust of a single tube generated by the deflagration of gunpowder be The total thrust Decomposed into axial components along the axis of the tube. Radial component perpendicular to the axis To balance range requirements and net-opening effectiveness, the proportion range of single-tube force is set as follows:

[0100] (26)

[0101] (27)

[0102] In the formula: The angle between the central axis of the projectile tube 10 and the central axis of symmetry of the device is the preset projectile angle.

[0103] The principle of fluid stagnation is used to convert kinetic energy into maximum static pressure. The formula for stagnation pressure is:

[0104] (28)

[0105] In the formula, This is the maximum total pressure reached when the fluid velocity stagnates to zero, used to eliminate uneven stress in porous structures. For hydrostatic pressure, The fluid velocity before impact with the flat bottom.

[0106] At the center of the flat bottom, the vertical velocity component ,at this time This creates a high-pressure center driving the surrounding inclined holes. Therefore, a flat-bottom structure is adopted internally, with a preferred flat-bottomed circumferential edge featuring a smooth transition chamfer (not shown in the figure). This chamfer eliminates stress concentration at the corners and guides the high-pressure airflow more smoothly into the surrounding ejection holes, avoiding energy dissipation from right-angle vortices. Ejection holes with a certain inclination angle are pre-fabricated. Elliptical flaring effect formula:

[0107] (29)

[0108] In the formula, Let be the effective entrance area of ​​the beveled hole on the flat bottom. The original circular cross-sectional area of ​​the tube.

[0109] Connector 6 and common cavity cap 8 are connected near the outlet end with a boss, and common cavity cap 8 has a corresponding groove. Utilizing the constant-volume locking principle from internal ballistics and the principle of datum plane coincidence in mechanical design, the initial volume fluctuation caused by the uncertainty of the thread engagement depth is eliminated. In sensitive systems with micro-charge and extremely small free volume, to break the error amplification chain of "assembly error—chamber depth change—peak pressure—fluctuation," a physical hard dead point needs to be constructed. Sensitivity analysis formula (differential of the adiabatic equation of state):

[0110] (30)

[0111] In the formula: This represents the axial error of the insertion depth. The gas insulation index is taken as 1.3.

[0112] Energy conversion efficiency of the high-pressure buffer chamber in this invention for

[0113] (31)

[0114] in The stagnation recovery efficiency represents the degree to which axial kinetic energy is converted into effective driving static pressure energy after the gas is injected into the chamber. It reflects the recovery capability of the staged diffuser structure for fluid kinetic energy, and is expressed by the formula:

[0115] (32)

[0116] In the formula: The local drag coefficient is generated by the first-stage sudden expansion and the second-stage flat-bottom impact. Because the design meets... The impact damage was minimized; For inlet dynamic pressure; This refers to frictional losses along the path.

[0117] in Vector efficiency measures the utilization rate of the energy component of the combustion gas along the axial direction of the eccentrically distributed nozzles. It reflects the effectiveness of converting static pressure energy into work done in the tube. The formula is expressed as follows:

[0118] (33)

[0119] In the formula: The projectile deflection angle is the angle between the tube axis and the central axis of symmetry of the device. According to vector decomposition, the effective work component is proportional to the cosine value. This is the orifice shrinkage loss coefficient.

[0120] in For rigid transmission efficiency, representing the elastic strain energy absorption of the chamber wall under extreme high-pressure impact, the formula is as follows:

[0121] (34)

[0122] In the formula: It is the elastic strain energy; This is the effect of the von Mises effect; This refers to the total chemical energy released by the explosive charge.

[0123] in Transient thermal efficiency measures the percentage of heat lost from the high-temperature combustion gas to the outside through the contact wall, expressed by the formula:

[0124] (35)

[0125] In the formula: Let be the convective heat transfer coefficient, and take . ; For effective heat exchange area; For transient temperature difference; Transient burst time.

[0126] Example

[0127] In a preferred embodiment, to clarify the engineering dimensions and dynamic performance of each structure, a set of core parameters of the present invention are provided here:

[0128] The maximum charge m in the ignition assembly 1 is 1.5g, and the actual peak pressure generated by its combustion within the small free volume of the system is approximately 120MPa. Setting the inner diameter r of the projectile tube 10 to 5.0mm, the total output flux area of ​​the device can be obtained using formula (1). It is 117.81mm 2 To perfectly cover the dynamic volume expansion of the traction body 11 at the moment of pipe exit, the optimal flow coefficient is selected. The inlet area of ​​the high-pressure buffer chamber can be obtained from formula (4). Approximately 149.62mm 2 Further calculations using formula (5) yielded the diameter of the medicine chamber 4. With a diameter of 13.8mm, this setting provides the system with approximately 20% intake redundancy, and the dimensions perfectly match the minor diameter of the M16 thread to ensure connection strength.

[0129] The high-pressure buffer chamber undergoes a two-stage diffusion process. Considering the compressibility correction of the high-pressure gas, boundary layer modification, and the asymmetry of the efficiency curve, the optimal area expansion ratio AR = 2.1 is chosen for the first-stage diffuser. The cross-sectional area of ​​the first stage is calculated using formula (10). The inner diameter of the first-stage diffuser cavity is then determined by formula (11). It is 20.0 mm. Referring to the height setting criteria described in the invention, the jet half-expansion angle is taken. The theoretical height of the first stage can be calculated using formula (12). It is 8.0mm.

[0130] The inner diameter of the second-stage stagnation chamber is further enlarged. Based on the principle that the flow field enters the complete stagnation zone when the total flow area expansion ratio reaches 3.0, the inner diameter of the second stage is calculated using formulas (14) and (15). It is approximately 23.9mm. To allow space for the chamfering process, it is set... It is 24.0mm. In the height design, a safety factor is used to prevent secondary throttling. The value is 1.2. Based on formulas (16) and (17), the second-stage stagnation chamber is obtained. Approximately 1.87 mm; to suppress pressure decay caused by dead volume, take =0.375 Based on (18), (19) and (20), the second-level stagnation cavity is derived. It is approximately 2.555 mm. Therefore, the height of the second stage of the high-pressure buffer chamber is... The range is 1.87–2.555 mm; in this example, the height of the second stage of the high-pressure buffer chamber is taken. =2.0mm. This height satisfies the potential energy core theory formula (23), ensuring that the airflow impacts the bottom flat surface with maximum kinetic energy without attenuation.

[0131] Referring to the rigid design principles described in the technical solution, to ensure the efficient conversion of gas energy into the working energy of the driving traction body 11, it is necessary to cut off the absorption of energy by the elastic deformation of the chamber wall. The high-pressure buffer chamber is made of structural steel, and its elastic modulus is... Poisson's ratio In this example, the quasi-rigid strain rate threshold of the system under a peak pressure impact of 120 MPa is set to 0.2%.

[0132] Extract the maximum inner radius in the chamber system (i.e., the inner diameter of the second-stage stagnation chamber) The half of the section is considered the most dangerous section with the weakest resistance to radial expansion. Using the Latin American thick-walled cylinder theory and the reverse derivation based on formula (25), the theoretical minimum outer radius required to maintain global quasi-rigidity is calculated to be approximately 16.58 mm. Combining the envelope design logic and taking into account both machining tolerances and lightweight requirements, the exterior of the high-pressure buffer chamber is designed as a uniform diameter columnar structure, and its effective pressure-bearing outer diameter is uniformly set. The inner radius is 33.38 mm (i.e., the actual outer radius is 16.69 mm). This achieves a uniform diameter cylindrical envelope design, utilizing the rigid redundancy of the most dangerous section to cover the entire segment, thereby cutting off the possibility of elastic deformation and energy absorption in all stepped chambers with a strict mechanical boundary. At this time, after verification by formula (24), the actual strain rate of the most dangerous section is approximately 0.195%, strictly meeting the design requirement of less than 0.2%. At the same time, the inner radius of the first stage is... Substituting the formula back into the equation, we find that the actual radial strain rate under ultimate impact is only 0.125%, ensuring that both the injection and stabilization stages are in an extremely high "quasi-rigid" state. This design, while meeting strength requirements, uses strict mechanical boundaries to eliminate the possibility of elastic deformation and energy absorption in all stepped chambers.

[0133] Referring to the proportional range determined by formulas (26) and (27), this embodiment selects a preset included angle of 15° for the projectile barrel 10. At this angle, approximately 96.6% of the axial component of the single-tube thrust is used for forward propulsion, ensuring that the device has extremely strong long-range strike capability; at the same time, approximately 2.6% of the equivalent thrust is converted into a radial component, which can generate a strong centrifugal effect at the moment the towing body 11 leaves the barrel, driving the flexible rope net 9 to accelerate opening and form a stable interception surface.

[0134] After determining the above-mentioned projectile angle, the conversion efficiency of kinetic energy to static pressure is further optimized using the principle of fluid stagnation. According to the stagnation pressure formula (28), when the high-pressure gas impacts the center of the flat bottom of the common cavity cap 8, the vertical velocity component... The pressure reaches the maximum total pressure. This forms a high-pressure center that effectively drives the gas flow to the surrounding inclined holes. In this embodiment, the flat-bottomed circumferential edge is provided with a smooth transition chamfer to guide the airflow smoothly into the inclined holes, avoiding energy dissipation caused by right-angle vortices. At the same time, the inlet of the ejection hole is optimized using the elliptical flaring effect formula (29). Based on a preset inclination angle of 15°, its effective inlet area is calculated. The cross-sectional area has increased by about 3.5% compared to the original circular shape, effectively reducing the inflow resistance when high-pressure gas enters the tube.

[0135] According to the sensitivity model (30) formula, without hard limiting constraints, a 0.5mm axial error generated by conventional threaded assembly will lead to a peak pressure fluctuation of up to 6.5%. Therefore, a specific design was implemented in the structure: the bottom of the inner cavity of the common cavity cap 8 (i.e., the second-stage stagnation cavity) forms an inwardly recessed stepped structure relative to its upper end face, so that the end face of the connector 6 and the stepped surface of the common cavity cap 8 form a rigid contact. Through this flange-type hard limiting design, the assembly error is set within the mechanical tolerance range (<0.05mm), thereby controlling the pressure consistency fluctuation within 0.6% and ensuring its stability.

[0136] According to the energy conversion efficiency model formula (31) of the high-pressure buffer chamber, the overall system efficiency is... Based on stagnation recovery efficiency Vector efficiency Rigid transmission efficiency and transient thermal efficiency This is a joint decision. Because the height setting of the second-stage stagnation chamber satisfies the potential energy core theory criterion, the airflow impact loss is minimized, and the stagnation recovery efficiency is maximized. Approximately 99.5%. Based on a preset included angle of 15°, and considering the orifice shrinkage loss coefficient. Given a value of 0.034, the vector efficiency is calculated using formula (33). Approximately 96.6%. Meanwhile, thanks to the "quasi-rigid" physical boundary provided by the equal-diameter columnar envelope structure, the elastic displacement of the chamber wall is limited to the micrometer level, resulting in a rigid transmission efficiency. It reaches 99.9%. Furthermore, the structure employs a flat, low-profile design, geometrically reducing the effective heat exchange area (approximately...). ), where the convective heat transfer coefficient h is taken as Transient temperature difference Approximately 2000K and maximum transient burst time Under the condition of 1ms operation, its transient thermal efficiency can be obtained from formula (35). Approximately 99.0%. Based on the above parameters, the overall energy conversion efficiency of the high-pressure buffer chamber of the device of this invention is calculated to be... With a success rate of approximately 95.17%, this efficient energy conversion mechanism, combined with a flange-type hard limit design based on the constant volume locking principle, not only ensures that the gas pressure can act instantaneously, uniformly, and in a common cavity on the six traction bodies 11, but also fundamentally solves the problem of non-common cavity operation caused by poor pressure consistency in multi-tube ejection devices.

[0137] Working principle of the net throwing: Under the drive of the common cavity gas, when the pressure exceeds the set start threshold, the common cavity of gas pushes the 6 traction bodies 11 placed in the 6 projectile tubes 10, so that they fly out at high speed in a fixed preset direction. The tail of each traction body 11 is connected to the flexible rope net 9. When the traction body 11 flies away from the outer shell 7, it pulls open the flexible rope net 9 to form a hexagonal interception net.

[0138] The entire working process of a lightweight common-cavity projectile net-catching device is as follows: This device can be mounted on a drone or other carrier platform. In standby mode, the ignition assembly 1 is connected to the net housing assembly 2, the flexible rope net 9 is folded and stored inside the outer shell 7, the traction body 11 is placed in the projectile tube 1, and the cover plate 12 is tightly fitted with the outer shell 7 to form a seal, ensuring that the device has a certain activation threshold. When the carrier platform detection system identifies and locks onto the target drone, it sends a trigger command to this device. The black powder in the ignition assembly 1 is electrically triggered and ignited, instantly generating high-temperature and high-pressure gas in the powder chamber 4. After the gas blows through the powder cap 5, it enters the common gas chamber of the common cavity cap 8, causing the internal pressure of the chamber to rise rapidly. When the pressure exceeds the activation threshold formed by the tight fit between the cover plate 12 and the outer shell 7, the six traction bodies 11 are propelled by the common cavity of the high-pressure gas and fly out at high speed along the preset direction of their respective projectile tubes 10. Each towing unit 11 is connected to the corresponding corner of the flexible rope net 9 at its tail. As the towing unit 11 flies away from the outer shell 7, it pulls open the flexible rope net 9, forming a hexagonal interception net in the air to entangle and capture the target drone. After the interception is completed, the independent modular net compartment component 2 can be quickly replaced, restoring the device to standby status and enabling reuse.

[0139] Compared to traditional net-capture methods such as magnetic deployment or mechanical ejection, the co-cavity high-pressure gas ejection interception method employed in this invention offers higher open-cavity co-location and spatiotemporal coverage consistency, thus more effectively addressing the diverse threats posed by unmanned aerial vehicles (UAVs). The high energy density and low recoil characteristics of the micro-powder gas propulsion, combined with the pressure uniform distribution mechanism of the co-cavity cap structure, enable the device to achieve rapid and stable ejection while ensuring the attitude stability of the carrier platform. The combination of lightweight modular design and a high-strength flexible interception net creates a UAV interception method that features rapid response, reliable capture, low collateral damage, and easy reusability.

[0140] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A lightweight concave projectile net trapping device, characterized in that, It includes a detachable ignition component (1) and a net chamber component (2); The net chamber component (2) includes a housing (7). A common cavity cap (8) is provided inside the housing (7). It also includes a plurality of projectile barrels (10) detachably connected to the common cavity cap. A traction body (11) is provided in each projectile barrel (10). A flexible rope net (9) connected to the traction body (11) is located inside the housing (7). A cover plate (12) is arranged at the outlet of the housing (7), and the cover plate (12) provides a starting pressure threshold; A high-pressure buffer chamber is formed between the ignition component (1) and the common cavity cap (8). The high-pressure buffer chamber adopts a hierarchical design of a first-stage diffuser chamber and a second-stage stagnation chamber, so that the dynamic pressure of the central axis has no attenuation, and the flow field enters the complete stagnation area, ensuring that the gas pressure acts on all traction bodies (11) instantaneously, uniformly and in a common cavity.

2. The apparatus according to claim 1, characterized in that, The ignition component (1) uses black powder or a gas generator as a controllable instantaneous power source, and generates high-pressure gas under electric trigger; and by making the transient release pressure of the gas generator equivalent to the peak pressure generated by the black powder charge of mg; The ignition component (1) uses black powder as a controllable instantaneous power source. The ignition component (1) includes a pressing pad (3), a chamber (4), a chamber cover (5) and a connector (6); An annular protrusion is provided on the outer periphery of the middle and lower part of the connector (6). An external thread connected to the common cavity cap (8) is provided on the outer wall of the lower side of the annular protrusion of the connector (6); A high-pressure buffer chamber is formed between the chamber cover (5), the connector (6) and the common cavity cap (8); Threads are engraved on the inner wall of the lower end of the chamber (4), and threads are engraved on the outer wall of the upper end of the chamber cover (5). The chamber (4) and the chamber cover (5) are threadedly connected, and black powder is loaded inside the chamber (4); "Cross" shaped pre-engraved grooves are engraved on the bottom of the chamber cover (5); A boss is provided on the outer side wall of the upper part of the chamber (4). The inner wall of the main body of the pressing pad (3) and the outer wall of the upper side of the annular protrusion of the connector (6) are threadedly connected; An annular limiting part that contacts and limits the upper surface of the boss of the chamber (4) is provided at the upper end of the pressing pad (3), and a step that contacts and positions the lower surface of the boss of the chamber (4) is provided on the inner wall surface of the upper part of the connector (6), realizing the complete limitation of the chamber (4).

3. The apparatus according to claim 2, characterized in that, The outer shell (7) and the common cavity cap (8) are threadedly connected; The number of projectile barrels (10) and traction bodies (11) is six; Six uniformly distributed threaded holes with a preset angle are provided inside the common cavity cap (8), and the threaded holes are used for threaded connection of six more projectile barrels (10); The tails of the six traction bodies (11) are connected to the flexible rope net (9) by tying ropes. When the traction bodies (11) fly out of the projectile barrels (10), the flexible rope net is pulled open to form a hexagonal flexible rope net; The cover plate (12) is tightly fitted with the outer shell (7), ensuring good sealing while making the device have a starting threshold, ensuring that the six traction bodies (11) are ejected in a common cavity.

4. The apparatus according to claim 1, characterized in that, The chamber cover (5) and the connector (6) are made of aluminum alloy; The material of the flexible rope net (9) is Dyneema material, the material of the projectile barrel (10) is carbon steel, and the material of the traction body (11) is tungsten alloy.

5. The apparatus according to claim 4, characterized in that, Drug chamber diameter Satisfy the following formula: ， in, , ， In the formula, This is the set value for the inlet area of ​​the high-pressure buffer chamber; A out The total output flux area of ​​the high-pressure buffer chamber is denoted by ; μ is the flow coefficient, and is the ratio of the total input flux area to the total output flux area, with a value range limited to: N represents the number of exits, and r represents the radius of each projectile tube.

6. The apparatus according to claim 5, characterized in that, The specific hierarchical design of the high-pressure buffer chamber adopting a first-stage diffuser chamber and a second-stage stagnation chamber is as follows: The part corresponding to the common cavity cap and the connector connection section is the first-stage diffuser cavity, and only the part corresponding to the common cavity cap is the second-stage stagnation cavity; the end of the first-stage diffuser cavity is provided with a transition section whose inner diameter expands from the inner diameter of the first-stage diffuser cavity body to the inner diameter of the second-stage stagnation cavity body; the outlet of the second-stage stagnation cavity is a flat-bottom structure, and the circumferential edge of the flat bottom is provided with a smooth transition chamfer, and the flat bottom body is uniformly provided with six ejection holes with a preset tilt angle θ.

7. The apparatus according to claim 6, characterized in that, Inner diameter of the first-stage diffuser The calculation is as follows: Based on the principle of energy conservation in fluid mechanics, a Bernoulli equation including an energy loss term is established between the inlet cross-section and the high-pressure buffer chamber cross-section: ， In the formula: This refers to the static pressure at the inlet of the injection channel. To restore the static pressure within the high-pressure buffer chamber. The average velocity of the fluid injected into the channel. The average velocity of the fluid within the high-pressure buffer chamber. For gas density, The mechanical energy loss caused by sudden expansion is defined by the "Porta-Carnot formula": ， Combining the above two equations, we can derive the pressure recovery amount during the conversion of kinetic energy into static pressure. : ， This leads to the pressure recovery coefficient for the conversion of kinetic energy into static pressure. Compared with area ratio The relationship is: ， In order to obtain The maximum value of, for Perform first derivative analysis: ， Setting the derivative to zero, we get =0.5, which is the optimal expansion ratio. ; Based on the set value of the inlet area of ​​the high-pressure buffer chamber The optimal cross-sectional area of ​​the first-stage diffuser in the high-pressure buffer chamber for: ， The corresponding high-pressure buffer chamber's first-stage diffuser inner diameter for: ； Axial distance of the first-stage diffuser The calculation is as follows: ， In the formula: For confined abrupt expansion turbulence, the angle of half-expansion of the jet is given. The value range is 0.325~0.

404. The radius of the first-stage diffuser chamber, The radius of the high-pressure buffer chamber inlet.

8. The apparatus according to claim 7, characterized in that, The diameter D2 of the second-stage stagnation chamber in the high-pressure buffer chamber needs to satisfy the following formula: ， ， The diameter of the second stage of the high-pressure buffer chamber The possible values ​​are: ， The axial distance H2 of the second-stage stagnation chamber in the high-pressure buffer chamber satisfies: The anti-blocking criterion based on the "continuity equation" is used to prevent... If the lateral air supply area is too small, it will cause secondary throttling when the lateral air supply area is smaller than the downstream load area. Therefore, a minimum physical height is set. Derivation formula: ， In the formula: , To prevent congestion and ensure safety; ， Under the premise of meeting gas supply requirements, high Each 1mm increase significantly increases the ineffective "dead volume"; if Further increases in dead volume will lead to increased peak pressure. Exponential decay; establish a volume-pressure sensitivity equation based on the adiabatic state equation. Differential form: ， In the formula: The gas insulation index is set to 1.

3. For dead volume increment, , Design the total free volume for this system; for a system with a charge of mg: ， The pressure fluctuation threshold should not be lower than 10% of the peak pressure, i.e. ， Depend on Satisfy the following formula: 。 9. The apparatus according to claim 8, characterized in that, The high-pressure buffer chamber is externally designed as a uniform diameter columnar structure, with an effective pressure-bearing outer diameter set at [value missing]. And satisfy ; Minimum outer radius required for high-pressure buffer chamber The calculation is as follows: Using the Latin American theory of thick-walled cylinders in solid mechanics, the radial displacement of a thick-walled cylinder under internal pressure is: ， In the formula, This refers to the radial displacement of the inner wall of the high-pressure buffer chamber. Design peak pressure within the cavity, The inner radius of the high-pressure buffer chamber; The outer radius of the high-pressure buffer chamber; The elastic modulus of the cavity material; The Poisson's ratio of the material; Combined with the definition of strain rate To meet Based on the rigid requirements, we can deduce the minimum outer radius required for the high-pressure buffer chamber by reverse derivation. The calculation model is as follows: 。 10. Use of the device according to any one of claims 1-9, characterized in that, Used for drone countermeasures, specifically: The device is mounted on the carrier platform; in standby mode, the ignition assembly and the net assembly remain connected, the flexible rope net is folded and stored inside the outer shell, the traction body is placed in the projectile tube, and the cover plate and the outer shell are tightly fitted to form a seal, ensuring that the device has a set start-up threshold. Once the carrier platform's detection system identifies and locks onto the target UAV, it sends a trigger command to the device. The black powder in the ignition assembly is electrically ignited, instantly generating high-temperature, high-pressure gas in the propellant chamber. After the gas destroys the propellant cap, it enters the gas chamber of the common cavity cap, causing the internal pressure of the chamber to rise rapidly. When the pressure exceeds the activation threshold formed by the tight fit between the cap and the outer shell, the six towing bodies, propelled by the common cavity of the high-pressure gas, fly out at high speed along the preset direction of their respective launch tubes. Each towing body is connected to the corresponding corner of the flexible rope net at its tail. As the towing body flies away from the shell, it pulls the flexible rope net open, forming a hexagonal interception net in the air to entangle and capture the target drone. After the interception is completed, the independent modular network warehouse component is replaced to restore the device to standby status and enable reuse.

Images