A test method for simulating the diffusion process of aluminum powder in an explosive field containing aluminum

Abstract

This invention provides an experimental method for simulating the diffusion process of aluminum powder in the explosion field of aluminum-containing explosives. The method involves mixing aluminum powder particles with inert material particles that have similar parameters such as density and impact impedance, and similar kinetic properties. These mixed particles replace the original aluminum powder particles in the aluminum-containing explosive sample, creating an aluminum-containing explosive sample. This sample weakens the intense combustion light of the aluminum powder particles during the explosion, facilitating the capture of particle cloud dispersion and diffusion images by high-speed cameras positioned axially and radially on the sample. The dynamic distribution space of the aluminum powder can be reconstructed from the obtained radial and axial images, determining its spatial volume change over time. This provides crucial data for the dynamic changes in aluminum powder concentration, solving the technical problem of lacking effective measurement methods for the spatiotemporal distribution and concentration evolution of aluminum powder particles in the explosion field of aluminum-containing explosive samples. This provides important technical support for the optimized design of aluminum-containing explosive sample formulations and charge structures.

Description

Technical Field

[0001] This invention belongs to the field of high-energy explosive performance testing technology, and relates to test methods, particularly a test method for simulating the diffusion process of aluminum powder in the explosion field of aluminum-containing explosives. Background Technology

[0002] Aluminum-containing explosives are a type of mixed explosive containing high-energy explosive components and high-calorific-value aluminum powder particles. They possess advantages such as high density, high energy, and high detonation temperature, and are widely used in various weapons and ammunition. During the detonation of aluminum-containing explosives, the high-energy explosive components first undergo a detonation reaction, generating high pressure and rapidly ejecting the internal aluminum powder particles outward, forming a dynamic cloud of aluminum powder particles in space. Simultaneously, the aluminum powder particles also undergo a rapid combustion reaction, releasing a large amount of heat energy, further increasing the shock wave energy and temperature of the blast field. The dynamic diffusion process of aluminum powder particles during the explosion, especially the volume of the aluminum powder particle cloud distribution space, directly determines the concentration of the aluminum powder cloud, which has a significant impact on the combustion rate and energy release characteristics of the aluminum powder. Therefore, the diffusion process and spatial dynamic distribution law of aluminum powder particles are of great concern in the formulation and charge structure design of aluminum-containing explosives.

[0003] When aluminum-containing explosives detonate, aluminum powder particles are distributed within the fireball formed by the explosion. This region has high pressure and temperature, making it difficult to obtain the dynamic concentration and kinetic parameters of the aluminum powder particles using contact sensors. High-speed cameras, due to the high brightness of the fireball, can only capture the changes in the outer contour of the fireball, failing to observe the internal conditions. Laser interferometers can only acquire the physical quantities of a small number of moving aluminum powder particles in a very small area, making it difficult to reflect the overall diffusion process of the aluminum powder cloud. While pulsed X-rays can shield against the strong light interference of the fireball, only images at 2-4 moments can be obtained, requiring close-range shooting in a limited space, further failing to reflect the overall diffusion process of the aluminum powder cloud. Therefore, testing the diffusion process of aluminum powder within the fireball of aluminum-containing explosives remains an unsolved technical challenge. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide an experimental method for simulating the diffusion process of aluminum powder in an aluminum-containing explosive explosion field, thereby solving the technical problem of the lack of means to measure the spatiotemporal distribution and concentration evolution of aluminum powder particles in an aluminum-containing explosive explosion field in existing technologies.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] An experimental method for simulating the diffusion process of aluminum powder in an aluminum-containing explosive explosion field includes the following steps:

[0007] Step 1: Mix the inert material particles and aluminum powder particles according to the formula to obtain mixed particles. Use the mixed particles to replace the aluminum powder particles in the aluminum-containing explosive to be tested to obtain a cylindrical aluminum-containing explosive sample.

[0008] Step 2: Place a detonating charge on the detonation end face of the prepared aluminum-containing explosive sample;

[0009] Step 3: Place the aluminum explosive sample on the support and set up a length scale next to the aluminum explosive sample; set up an axial high-speed camera and a radial high-speed camera along the axial and radial directions of the aluminum explosive sample, respectively, and the optical paths of the axial high-speed camera and the radial high-speed camera are perpendicular to each other; determine the image magnification ratio of the axial high-speed camera and the radial high-speed camera respectively.

[0010] Step 4: Detonate the aluminum-containing explosive sample. Use an axial high-speed camera and a radial high-speed camera to acquire axial and radial images of the detonation process of the aluminum-containing explosive sample, respectively.

[0011] Step 5: Preprocess the radial and axial images to obtain preprocessed radial and axial images; determine the detonation end region, middle region, and tail region in the preprocessed radial image; divide the first boundary line between the detonation end region and the middle region, and divide the second boundary line between the middle region and the tail region; determine the vertical distance between the first and second boundary lines, and multiply the vertical distance by the image magnification ratio of the radial high-speed camera to obtain the height of the middle region;

[0012] The axial image acquired by the axial high-speed camera is preprocessed to obtain the preprocessed axial image. The inner and outer boundary lines of the annular particle cloud in the preprocessed axial image are divided to determine the inner and outer diameters of the annular particle cloud in the preprocessed axial image. The determined inner and outer diameters are multiplied by the image magnification ratio of the axial high-speed camera to obtain the inner and outer diameters of the actual annular particle cloud.

[0013] Step 6: Construct a ring using the inner diameter, outer diameter, and height of the central region of the actual ring-shaped particle cloud at the same acquisition time as construction parameters, and calculate the volume of the ring at that time.

[0014] Step 7: Plot the curve of the torus volume changing with time based on the calculated volume of the torus at different times.

[0015] The present invention also has the following technical features:

[0016] Specifically, the inert materials include lithium fluoride, calcium carbonate, and aluminum oxide.

[0017] Furthermore, the ratio of the average particle size of the inert material particles to the aluminum powder particles is (0.75~1.25):1.

[0018] Furthermore, when the mass percentage of mixed particles in the aluminum explosive sample is less than 10%, the mass ratio of inert material to aluminum powder is (0.5~1):1; when the mass percentage of mixed particles in the aluminum explosive sample is 10%~20%, the mass ratio of inert material to aluminum powder is (1~3):1; when the mass percentage of mixed particles in the aluminum explosive sample is greater than 20%, the mass ratio of inert material to aluminum powder is (3~4.5):1.

[0019] Furthermore, the diameter of the detonating charge is not less than 10 mm and the height is not less than 10 mm.

[0020] Furthermore, the optical axis of the axial high-speed camera coincides with the axis of the aluminum explosive sample.

[0021] Furthermore, the imaging frequency of the axial high-speed camera and the radial high-speed camera is not less than 1×10⁻⁶. 5 fps, with an exposure time of 0.5~2μs.

[0022] Furthermore, the volume of the toroidal body is determined by the following formula:

[0023]

[0024] In the formula,

[0025] V This represents the volume of the toroid, in m³.

[0026] d max The outer diameter of the annular granular cloud is expressed in meters (m).

[0027] d min The inner diameter of the annular particle cloud is expressed in meters (m).

[0028] h The height is for the central region, in meters (m).

[0029] Furthermore, the preprocessing includes grayscale conversion, denoising, and image binarization.

[0030] Compared with the prior art, the beneficial technical effects of this invention are:

[0031] (1) The method of the present invention mixes inert material particles and aluminum powder particles in a certain ratio. On the one hand, it weakens the strong light generated by the explosion of aluminum explosive sample, so that the distribution of aluminum powder inside can be observed through the outer surface of the fireball during the simulation test. On the other hand, a small amount of aluminum powder particles in the aluminum explosive sample provide a moderately bright lighting source for the imaging of particle movement trajectory through their own long-term combustion reaction, so that a large range of particle movement images can be obtained without external auxiliary lighting during the test.

[0032] (2) The method of the present invention is simple. The outer diameter of the obtained mixed particle cloud is consistent with the diameter of the original aluminum explosive sample explosion fireball in terms of spatial variation. Therefore, the two can be directly compared, which facilitates the analysis of the experimental measurement accuracy and ensures the accuracy of the experimental results. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the explosion test layout of the present invention.

[0034] Figure 2 This is a high-speed photographic image taken radially 300 microseconds after detonation in Example 1.

[0035] Figure 3 This is a high-speed photographic image taken 300 microseconds after detonation, observed from the axial direction in Example 1.

[0036] Figure 4 This is the characteristic size variation curve of the central region of the mixed particle cloud obtained in Example 1.

[0037] Figure 5 This is a schematic diagram of the three-dimensional annulus where the main distribution area of ​​the mixed particles in Example 1 is located.

[0038] Figure 6 This is the volume change curve of the main distribution area of ​​the mixed particles obtained in Example 1.

[0039] The meanings of the labels in the diagram are as follows:

[0040] 1-Aluminum-containing explosive sample, 2-Expanding explosive charge, 3-Detonator, 4-Axial high-speed camera, 5-Radial high-speed camera.

[0041] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0042] It should be noted that, unless otherwise specified, all components and raw materials in this invention are those known in the prior art.

[0043] The technical concept of this invention is as follows: In the initial stage of an aluminum-containing explosive explosion, the aluminum powder particles inside do not participate in the reaction. They only burn intensely and emit strong light after being dispersed into a certain space. Therefore, without significantly affecting the early detonation driving energy of the aluminum-containing explosive sample, inert material particles with similar parameters to aluminum powder (such as gas drag during flight and deformation after impact) can be mixed with aluminum powder particles to obtain mixed particles. These mixed particles can then replace the original aluminum powder particles in the aluminum-containing explosive sample to prepare an aluminum-containing explosive sample. This type of aluminum-containing explosive sample can moderately weaken the explosion. The intense light emitted during the combustion of aluminum powder particles during the process facilitates the clear capture of images of particle cloud dispersion and diffusion within the explosion field by high-speed cameras positioned along the axial and radial axes of the aluminum explosive sample. Based on the radial and axial images, the dynamic distribution space of the aluminum powder particles can be reconstructed, thereby determining the change in their spatial volume over time. This provides crucial data for the dynamic changes in aluminum powder particle concentration, thus solving the technical challenge of lacking effective measurement methods for the spatiotemporal distribution and concentration evolution of aluminum powder particles in the explosion field of aluminum explosive samples. It also provides important technical support for the optimized design of aluminum explosive sample formulations and charge structures.

[0044] It should be noted that in this invention, granules and powder are the same concept.

[0045] Aluminum-containing explosives refer to mixed explosives with fine aluminum powder added to the formula. By mass percentage, they include the following components: 55%~85% high-energy single-element explosives (such as TNT, RDX, Octogen, etc.), 8%~35% aluminum powder, and 2%~15% desensitizer / binder, with the total mass percentage of each component being 100%.

[0046] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0047] Example 1:

[0048] Following the above technical solutions, such as Figures 1 to 6 As shown in the figure, this embodiment provides an experimental method for simulating the diffusion process of aluminum powder in an aluminum-containing explosive explosion field, including the following steps:

[0049] Step 1: Mix the inert material particles and aluminum powder particles according to the formula to obtain mixed particles. Use the mixed particles to replace the aluminum powder particles in the aluminum-containing explosive to be tested to prepare a cylindrical aluminum-containing explosive sample 1.

[0050] In this embodiment, the aluminum-containing explosive to be tested is a press-fit type aluminum-containing explosive with octogen (HMX) as the main component. The aluminum-containing explosive sample, by mass percentage, includes the following components: 65% octogen, 30% mixed particles, and 5% desensitizer / binder, with the mass ratio of inert particles to aluminum powder particles in the mixed particles being 4:1. During preparation, lithium fluoride particles with an average particle size of 15 μm and aluminum powder particles with an average particle size of 13 μm are first mixed at a mass ratio of 4:1 to obtain mixed particles; then, the mixed particles are mixed with octogen explosive particles and a binder; finally, a press-fit aluminum-containing explosive sample 1 with a mass of 800 g and dimensions of Φ80 mm × 87 mm is prepared using a press-fit process.

[0051] Step 2: Set a detonating charge 2 on the detonation end face of the aluminum explosive sample 1, and set a detonator 3 at the front end of the detonating charge 22;

[0052] Preferably, the diameter of the detonating charge 22 is 25mm and the height is 25mm.

[0053] Step 3, as follows Figure 1 As shown, aluminum explosive sample 1 is positioned axially (horizontally) on a fixed support in the explosion-proof laboratory, 1.5m above the ground. Axial high-speed camera 4 and radial high-speed camera 5, both Kirana 05M models manufactured by SI Company (UK), are positioned along the axial and radial axes of sample 1, respectively, with the optical paths of axial high-speed camera 4 and radial high-speed camera 5 perpendicular. A rod of length [missing information] is placed at the location of aluminum explosive sample 1. L The length scales are used to determine the image magnification ratios of the axial high-speed camera 4 and the radial high-speed camera 5, respectively: still images are captured using the axial high-speed camera 4 and the radial high-speed camera 5, and the lengths of the length scales in the still images are measured using existing image processing software, and denoted as follows: , Thus, the optical path of the axial high-speed camera 4 and the image magnification ratio of the radial high-speed camera 5 are calculated and denoted as follows: and ,in, , .

[0054] Step 4: Detonate aluminum explosive sample 1. Use axial high-speed camera 4 and radial high-speed camera 5 to acquire axial and radial images of the detonation process of aluminum explosive sample 1, respectively.

[0055] The parameters of the axial high-speed camera 4 and the radial high-speed camera 5 are set. In this embodiment, the imaging frequency of both the axial high-speed camera 4 and the radial high-speed camera 5 is set to 2×10. 5With the exposure time set to 1 μs and the frame rate set to fps, the aluminum explosive sample 1 was detonated after all preparations were completed.

[0056] Step 5: Preprocess the radial and axial images to obtain preprocessed radial and axial images; determine the detonation end region, middle region, and tail region in the preprocessed radial image; divide the first boundary line between the detonation end region and the middle region, and divide the second boundary line between the middle region and the tail region; determine the vertical distance between the first and second boundary lines, and multiply the vertical distance by the image magnification ratio of the radial high-speed camera to obtain the height of the middle region;

[0057] The preprocessing includes grayscale conversion, denoising, and image binarization.

[0058] In this embodiment, the radial image obtained by the radial high-speed camera 5 is preprocessed to obtain the following image: Figure 2 The image shown, Figure 2 The black areas in the image are formed by a mixture of aluminum powder particles and lithium fluoride particles. Because the detonation flash of the octogen (HMX) contained in aluminum explosive sample 1 is short-lived, the bright light captured is primarily due to the combustion of aluminum powder particles. Since the mass proportion of aluminum powder particles in this mixture is only 20%, the concentration of aluminum powder particles during diffusion is low, allowing for effective control of the combustion rate and moderate brightness of the flame. This enables the acquisition of clear particle motion images without external auxiliary lighting during the experiment. Simultaneously, the reduced combustion rate of the aluminum powder particles prolongs their combustion time, allowing for extended recording of the particle motion process.

[0059] Figure 2 The mixed particle image shown can be visually divided into three regions: the initiation region, the middle region, and the tail region. As can be seen from the image, there are clear boundaries between these three regions, with particular attention needed to the middle region. A first boundary line is drawn between the initiation region and the middle region, and a second boundary line is drawn between the middle region and the tail region. The vertical distance between the first and second boundary lines is then determined. The vertical distance multiplied by the radial magnification of the high-speed camera image. The height of the central region was obtained. The final result obtained during the detonation of aluminum-containing explosive sample 1 h The curve of change over time is as follows Figure 4 As shown.

[0060] In other solutions, existing software can be used to define the boundaries. Specifically, the boundaries are determined based on the inflection points of the grayscale values ​​of the image pixels. That is, when the image changes from bright to dark, the grayscale of the image pixels decreases continuously; when the image changes from dark to bright, the grayscale of the image pixels gradually increases. The inflection points can then be used as the boundaries.

[0061] The axial image acquired by the axial high-speed camera 4 is preprocessed to obtain the preprocessed axial image; the inner and outer boundary lines of the annular particle cloud in the preprocessed axial image are divided, and the inner and outer diameters of the annular particle cloud in the preprocessed axial image are determined. The determined inner and outer diameters are multiplied by the image magnification ratio of the axial high-speed camera to obtain the inner and outer diameters of the actual annular particle cloud.

[0062] The axial images acquired by the axial high-speed camera 4 are as follows Figure 3 As shown in the figure, the black area represents a mixture of aluminum powder and lithium fluoride particles. Figure 2 The detonation head and tail regions shown contain fewer aluminum powder particles, therefore Figure 3 The displayed ring represents the particle cloud morphology of the central region, meaning the particle cloud in the central region approximates a ring shape. This indicates that although the aluminum powder in aluminum-containing explosive sample 1 is uniformly distributed, during the explosion, the aluminum powder particles are mainly distributed in the annular region near the edge of the fireball. Extracting the inner and outer boundary lines of this annular particle cloud image yields the diameter of the inner boundary of the image. and the diameter of the outer boundary This allows us to determine the inner diameter of the actual annular particle cloud. and outer diameter Finally, the inner diameter of the actual annular particle cloud during the detonation of aluminum explosive sample 1 was obtained. and outer diameter The curve of change over time is as follows Figure 4 As shown.

[0063] Step 6: Construct a ring using the inner diameter, outer diameter, and height of the central region of the actual ring-shaped particle cloud at the same acquisition time as construction parameters, and calculate the volume of the ring at that time.

[0064] In this embodiment, the structure of the three-dimensional annulus in which the main distribution area of ​​the mixed particles is located is as follows: Figure 5 As shown.

[0065] Step 7: Plot the curve of the torus volume changing with time based on the calculated volume of the torus at different times.

[0066] Since the concentration of aluminum powder is a key physical quantity affecting its subsequent reaction rate, the focus of studying the aluminum powder diffusion process is to obtain the change in its distribution volume. Because the mass of aluminum powder is known, once the volume is obtained, the change in its concentration can be calculated. The curve of the toroidal volume changing with time plotted in this embodiment is shown below. Figure 6 As shown.

[0067] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0068] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0069] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A test method for simulating the diffusion process of aluminum powder in an aluminum-containing explosive explosion field, characterized in that, Includes the following steps: Step 1: Mix the inert material particles and aluminum powder particles according to the formula to obtain mixed particles. Use the mixed particles to replace the aluminum powder particles in the aluminum explosive to be tested to prepare a cylindrical aluminum explosive sample (1). Step 2: Place a detonating charge (2) on the detonation end face of the aluminum explosive sample (1). Step 3: Place the aluminum explosive sample (1) on the support and set a length scale next to the aluminum explosive sample (1); set an axial high-speed camera (4) and a radial high-speed camera (5) along the axial and radial directions of the aluminum explosive sample (1), respectively, and the optical paths of the axial high-speed camera (4) and the radial high-speed camera (5) are perpendicular to each other; determine the image magnification ratio of the axial high-speed camera (4) and the radial high-speed camera (5) respectively. Step 4: Detonate the aluminum explosive sample (1). Use an axial high-speed camera (4) and a radial high-speed camera (5) to collect axial and radial images of the detonation process of the aluminum explosive sample (1). Step 5: Preprocess the radial and axial images to obtain the preprocessed radial and axial images; determine the detonation end region, middle region, and tail region in the preprocessed radial image; divide the first boundary line between the detonation end region and the middle region, and divide the second boundary line between the middle region and the tail region; determine the vertical distance between the first boundary line and the second boundary line, and multiply the vertical distance by the image magnification ratio of the radial high-speed camera (5) to obtain the height of the middle region; The axial image acquired by the axial high-speed camera (4) is preprocessed to obtain the preprocessed axial image; the inner and outer boundary lines of the annular particle cloud in the preprocessed axial image are divided, and the inner and outer diameters of the annular particle cloud in the preprocessed axial image are determined. The determined inner and outer diameters are multiplied by the image magnification ratio of the axial high-speed camera (4) to obtain the inner and outer diameters of the actual annular particle cloud. Step 6: Construct a ring using the inner diameter, outer diameter, and height of the central region of the actual ring-shaped particle cloud at the same acquisition time as construction parameters, and calculate the volume of the ring at that time. Step 7: Plot the curve of the torus volume changing with time based on the calculated volume of the torus at different times.

2. The experimental method for simulating the diffusion process of aluminum powder in an aluminum-containing explosive explosion field as described in claim 1, characterized in that, The inert materials include lithium fluoride, calcium carbonate, and aluminum oxide.

3. The experimental method for simulating the diffusion process of aluminum powder in an aluminum-containing explosive explosion field as described in claim 1, characterized in that, The ratio of the average particle size of the inert material particles to the aluminum powder particles is (0.75~1.25):

1.

4. The experimental method for simulating the diffusion process of aluminum powder in an aluminum-containing explosive explosion field as described in claim 1, characterized in that, When the mass percentage of mixed particles in the aluminum explosive sample (1) is less than 10%, the mass ratio of inert material to aluminum powder is (0.5~1):1; when the mass percentage of mixed particles in the aluminum explosive sample (1) is 10%~20%, the mass ratio of inert material to aluminum powder is (1~3):1; when the mass percentage of mixed particles in the aluminum explosive sample (1) is greater than 20%, the mass ratio of inert material to aluminum powder is (3~4.5):

1.

5. The experimental method for simulating the diffusion process of aluminum powder in an aluminum-containing explosive explosion field as described in claim 1, characterized in that, The diameter of the detonating charge (2) is not less than 10 mm and the height is not less than 10 mm.

6. The experimental method for simulating the diffusion process of aluminum powder in an aluminum-containing explosive explosion field as described in claim 1, characterized in that, The optical axis of the axial high-speed camera (4) coincides with the axis of the aluminum explosive sample (1).

7. The experimental method for simulating the diffusion process of aluminum powder in an aluminum-containing explosive explosion field as described in claim 1, characterized in that, The imaging frequencies of the axial high-speed camera (4) and the radial high-speed camera (5) are not less than 1×10⁻⁶. 5 fps, with an exposure time of 0.5~2μs.

8. The experimental method for simulating the diffusion process of aluminum powder in an aluminum-containing explosive explosion field as described in claim 1, characterized in that, The volume of the toroid is determined by the following formula: In the formula, V This represents the volume of the toroid, in m³. d max The outer diameter of the annular granular cloud is expressed in meters (m). d min The inner diameter of the annular particle cloud is expressed in meters (m). h The height is for the central region, in meters (m).

9. The experimental method for simulating the diffusion process of aluminum powder in an aluminum-containing explosive explosion field as described in claim 1, characterized in that, The preprocessing includes grayscale conversion, noise reduction, and image binarization.

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