Bird strike test cluster launching high speed shell and its design method

Abstract

The application belongs to the field of aero-engine test, and particularly relates to a bird impact test group gun launching high-speed shell design method, which is based on the shape of a uniform thin-walled cylinder structure shell, constructs a three-dimensional numerical simulation model of the shell and a shell ejection device, calculates stress and deformation results of the shell when the shell impacts the shell ejection device at a high bird speed, and finds out stress weak positions and displacement weak positions of the structure; the minimum size bird body that can be accommodated in the middle section and the rear section of the shell is taken as a constraint, the minimum inner diameters of the middle section and the rear section of the shell and the optimal buckling mode of the shell are taken as optimization targets, and the shell structure is subjected to topology optimization to obtain an initial shell profile; the internal stress of the shell does not exceed the material failure stress, and the total mass of the shell does not exceed the original mass, which are taken as constraint conditions, and the maximum energy absorption of the front end of the shell and the minimum deformation of the middle section and the rear section are taken as optimization targets, and the shell structure is subjected to topology optimization of size and shape to obtain an optimized shell.

Description

A bird strike test group cannon firing high-velocity projectile casing and its design method Technical Field

[0001] This application belongs to the field of aero-engine testing, and specifically relates to a high-speed projectile casing for bird strike test arrays and its design method. Background Technology

[0002] Bird strike tests are an essential and indispensable part of the engine airworthiness certification process. Various airworthiness regulations have specific requirements for bird strike tests, specifying the weight and number of birds under different conditions. The weight and number of birds vary depending on the area of ​​the engine's air intake throat.

[0003] Group firing refers to the process of using multiple air cannons to launch a specified weight and number of birds at the engine at regular intervals. To simulate the engine-bird collision process, the launch velocity of the birds needs to be controlled, usually at a speed comparable to the aircraft's takeoff speed. A high-velocity cartridge case, the device carrying the bird, is typically placed inside the air cannon barrel. It accelerates along with the bird within the barrel and stops at the muzzle due to a hollow ejection device. The bird then exits through the central hole of the ejection device, completing the bird launch.

[0004] Currently, most existing high-velocity cartridge cases employ a uniform thin-walled cylindrical structure, machined from lightweight, high-deformation-rate aluminum. Before launching the bird, a foam or plastic liner is pasted inside the thin-walled cylinder to reduce the inner diameter of the cartridge case, allowing the bird to smoothly exit through the central hole after impacting the hollow ejection device. For salvo firing, multiple lined thin-walled cartridge cases are required to accommodate varying bird weights and numbers.

[0005] The shortcomings of existing technical solutions are as follows:

[0006] Firstly, from a technical perspective, the ejection device is limited by the structure of the multi-gun firing system, thus restricting its impact load capacity. Therefore, the cartridge case mass cannot be too large during high-speed firing. This necessitates that the thickness of the uniformly thin-walled cartridge case be less than a fixed value, thereby limiting its impact resistance. When the firing velocity increases further, the cartridge case is highly susceptible to cracking upon impact with the ejection device, potentially even producing fragments that enter the engine intake, posing a serious threat to test safety.

[0007] Secondly, in terms of cost, existing cartridge cases require an inner liner to be attached before firing to reduce the inner diameter of the cartridge case and ensure the bird can fly out smoothly. Therefore, when manufacturing bird cartridge cases, it is necessary not only to purchase an inner liner of the same size, but also to ensure the machining accuracy of the inner surface of the cartridge case during processing, all of which increase the manufacturing cost of the cartridge case.

[0008] Finally, regarding efficiency, after impacting the ejector, the uniformly thin-walled cartridge case undergoes significant plastic expansion deformation at the front end and severe compressive deformation at the middle and rear ends. These forces create outward-expanding pressure inside the barrel, pressing against the inner wall and making cartridge case removal extremely difficult. This significantly reduces testing efficiency during multi-shot swarm firing. Summary of the Invention

[0009] This application provides a design method for high-velocity projectile casings used in bird strike test artillery groups, focusing on solving problems such as high-velocity casing cracking, high testing costs, and low dismantling efficiency. This application includes:

[0010] Step S1: Based on the shape of the uniform thin-walled cylindrical shell, construct a three-dimensional numerical simulation model of the shell and the ejection device, calculate the stress and deformation results when the shell impacts the ejection device at high bird speed, and find the stress weak points and displacement weak points of the structure.

[0011] Step S2: With the constraint that the middle and rear sections of the cartridge case can accommodate the smallest bird body, and with the optimization objectives of minimizing the inner diameter of the middle and rear sections of the cartridge case and optimizing the cartridge case buckling mode, topology optimization is performed on the cartridge case structure to obtain the initial cartridge case profile.

[0012] Step S3: Using the constraints that the internal stress of the cartridge case does not exceed the material failure stress and the total mass of the cartridge case does not exceed the original mass, and taking the maximum energy absorption at the front end of the cartridge case and the minimum deformation of the middle and rear sections as optimization objectives, the size and shape of the cartridge case structure are optimized to obtain the optimized cartridge case.

[0013] Preferably, after step S3, there is a step S4: the optimized cartridge case structure is processed and prototyped, the prototype is tested on the multi-gun firing device, and the structural details are improved according to the test results until the requirements of the cartridge case not cracking at high speed, the bird body can pass smoothly through the center hole of the ejection device, and the cartridge case can be easily removed from the gun barrel after firing are met.

[0014] A high-velocity projectile casing for bird strike test artillery firing, designed using the aforementioned design method for high-velocity projectile casings for bird strike test artillery firing, is characterized by comprising an expansion section and a straight section. The expansion section is located at the front end of the projectile casing, and the rear end of the expansion section is connected to the straight section. The expansion section gradually expands from the rear end to the front end.

[0015] Preferably, the connection between the expansion section and the straight section has an annular support structure formed by radially protruding outer wall of the cartridge case.

[0016] Preferably, the radius of the support structure is less than or equal to the maximum diameter of the expansion section.

[0017] The advantages of this application include:

[0018] 1. The high-speed projectile case prepared by this invention through optimization iteration, trial production, and live-fire testing can maintain structural integrity under high-speed impact of 165m / s, with no cracks or fragments generated in the projectile case, which greatly ensures the safety of bird strike tests on aero engines and improves the reliability of the test.

[0019] 2. The high-speed cartridge case prepared by this invention does not require an inner liner structure, which saves testing costs and eliminates the risk of the inner liner accidentally falling off and flying into the engine;

[0020] 3. The high-speed cartridge case prepared by this invention has very little deformation at the front and rear ends after impacting the ejector, making it easier to disassemble and significantly reducing the test and debugging time for multi-bird-body swarm gun firing. Attached Figure Description

[0021] Figure 1 is a flowchart of a preferred embodiment of the design method for high-speed projectile casings fired from a bird strike test group according to this application.

[0022] Figure 2 is a schematic diagram of a bird strike test group firing a high-speed projectile casing according to a preferred embodiment of this application. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are only some, not all, of the embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0024] As shown in Figure 1, this application provides a design method for high-speed projectile casings fired from a bird strike test group, including:

[0025] Step S1: Based on the shape of the uniform thin-walled cylindrical shell, construct a three-dimensional numerical simulation model of the shell and the ejection device, calculate the stress and deformation results when the shell impacts the ejection device at high bird speed, and find the stress weak points and displacement weak points of the structure.

[0026] Step S2: With the constraint that the middle and rear sections of the cartridge case can accommodate the smallest bird body, and with the optimization objectives of minimizing the inner diameter of the middle and rear sections of the cartridge case and optimizing the cartridge case buckling mode, topology optimization is performed on the cartridge case structure to obtain the initial cartridge case profile.

[0027] Step S3: With the constraints that the internal stress of the cartridge case does not exceed the material failure stress and the total mass of the cartridge case does not exceed the original mass, and with the optimization objectives that the front end of the cartridge case absorbs the maximum energy and the middle and rear sections deform the least, the size and shape of the cartridge case structure are optimized to obtain the optimized cartridge case. When the front end of the cartridge case absorbs the maximum energy, the front end has the greatest impact resistance after the cartridge case hits the ejector and is not easily deformed. On the one hand, it can facilitate the removal of the cartridge case and greatly reduce the test and debugging time of multi-bird group gun firing. On the other hand, it can protect the middle and rear sections.

[0028] Step S4: The optimized cartridge case structure is processed and prototyped. The prototype is tested on the multi-gun firing device. The structural details are improved based on the test results until the requirements of high-speed firing of the cartridge case without cracking, the bird body can pass smoothly through the center hole of the ejection device, and the cartridge case can be easily removed from the gun barrel after firing are met. In addition, the topology and mass distribution of the cartridge case are reasonably optimized so that the front end of the cartridge case can absorb most of the impact energy without cracking after high-speed impact with the ejection device.

[0029] A high-velocity projectile casing for bird strike test artillery firing, designed using the aforementioned design method, includes an expanding section and a straight section. The expanding section is located at the front end of the casing, and the rear end of the expanding section connects to the straight section. The expanding section gradually expands from the rear end to the front end. This variable-diameter structure allows birds of different sizes to fit snugly inside the casing, eliminating the need for attaching an inner liner, thus saving testing costs and preparation time. Furthermore, it relaxes the requirements for the machining precision of the casing's inner surface, reducing the cost and time required for the machining and prototyping process.

[0030] Preferably, the connection between the expansion section and the straight section has an annular support structure formed by radial protrusions on the outer wall of the cartridge case. This ensures that the cartridge case can run smoothly inside the gun barrel and also improves the buckling mode of the straight section of the cartridge case, making it less likely to generate expansion pressure that squeezes the gun barrel. This makes the disassembly process smoother and improves the test efficiency when firing multiple guns.

[0031] Preferably, the radius of the support structure is less than or equal to the maximum diameter of the expansion section.

[0032] The advantages of this application include:

[0033] 1. The high-speed projectile case prepared by this invention through optimization iteration, trial production, and live-fire testing can maintain structural integrity under high-speed impact of 165m / s, with no cracks or fragments generated in the projectile case, which greatly ensures the safety of bird strike tests on aero engines and improves the reliability of the test.

[0034] 2. The high-speed cartridge case prepared by this invention does not require an inner liner structure, which saves testing costs and eliminates the risk of the inner liner accidentally falling off and flying into the engine;

[0035] 3. The high-speed cartridge case prepared by this invention has very little deformation at the front and rear ends after impacting the ejector, making it easier to disassemble and significantly reducing the test and debugging time for multi-bird-body swarm gun firing.

[0036] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A design method for high-speed projectile casings fired in a bird strike test group, characterized in that, include: Step S1: Based on the uniform thin-walled cylindrical shell shape, construct a three-dimensional numerical simulation model of the shell and ejection device, calculate the stress and deformation results when the shell impacts the ejection device at high bird speed, and identify the stress-weak and displacement-weak locations of the structure; Step S2: With the constraint that the middle and rear sections of the shell can accommodate the smallest bird body, and with the optimization objectives of minimizing the inner diameter of the middle and rear sections and optimizing the buckling mode of the shell, perform topology optimization on the shell structure to obtain the initial shell profile; Step S3: With the constraints that the internal stress of the shell does not exceed the material failure stress and the total mass of the shell does not exceed the original mass, and with the optimization objectives of maximizing the energy absorption at the front end of the shell and minimizing the deformation of the middle and rear sections, perform topology optimization on the size and shape of the shell structure to obtain the optimized shell.

2. The design method for high-speed projectile casings fired in bird strike test groups as described in claim 1, characterized in that, Step S3 is followed by step S4: the optimized cartridge case structure is processed and prototyped, and the prototype is tested on the multi-gun firing device. The structural details are improved based on the test results until the requirements are met: the cartridge case does not crack at high speed, the bird can pass smoothly through the center hole of the ejection device, and the cartridge case can be easily removed from the gun barrel after firing.

3. A high-velocity projectile case for bird strike test artillery, designed using the design method for high-velocity projectile cases for bird strike test artillery as described in any one of claims 1-2, characterized in that, It includes an expansion section and a straight section. The expansion section is located at the front end of the cartridge case, and the rear end of the expansion section is connected to the straight section. The expansion section gradually expands from the rear end to the front end.

4. The bird strike test group gun firing high-velocity projectile casing as described in claim 3, characterized in that, The connection between the expansion section and the straight section has an annular support structure formed by radially protruding outer wall of the cartridge case.

5. The bird strike test group gun firing high-velocity projectile casing as described in claim 4, characterized in that, The radius of the support structure is less than or equal to the maximum diameter of the expansion section.

Images