Test method for simulating aluminum powder diffusion process in aluminum-containing explosive explosion field

Abstract

The invention provides a test method for simulating an aluminum powder diffusion process in an aluminum-containing explosive explosion field, which comprises the following steps of: mixing inert material particles with aluminum powder particles to obtain mixed particles, and replacing original aluminum powder particles in an aluminum-containing explosive sample with the mixed particles, the sample can weaken the burning strong light of aluminum powder particles in the explosion process, so that high-speed cameras arranged in the axial direction and the radial direction of the aluminum-containing explosive sample can conveniently capture scattering and diffusion images of particle clouds in an explosion field; the dynamic distribution space of the aluminum powder can be reconstructed according to the obtained radial image and axial image, the change process of the space volume along with time is determined, key data is provided for the dynamic change of the concentration of the aluminum powder, and the technical problem that the spatial and temporal distribution and concentration evolution process of aluminum powder particles in an aluminum-containing explosive sample explosion field are lack of effective measurement means is solved. And important technical support is provided for optimal design of an aluminum-containing explosive sample formula and a charging structure.

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: An experimental method for simulating the diffusion process of aluminum powder in an aluminum-containing explosive explosion field includes the following steps: Step 1, mixing the inert material particles with the aluminum powder particles in a formula amount to obtain mixed particles, and using 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; Step 2, setting an expanding explosive column on the end face of the prepared aluminum-containing explosive sample; Step 3, placing the aluminum-containing explosive sample on a support, setting a length scale beside the aluminum-containing explosive sample, setting an axial high-speed camera and a radial high-speed camera along the axial and radial directions of the aluminum-containing explosive sample, and the optical paths of the axial high-speed camera and the radial high-speed camera are perpendicular to each other; and determining the image magnification ratios of the axial high-speed camera and the radial high-speed camera, respectively; Step 4, initiating the aluminum-containing explosive sample, and using the axial high-speed camera and the radial high-speed camera to collect axial images and radial images of the initiation process of the aluminum-containing explosive sample, respectively; Step 5, preprocessing the radial images and the axial images to obtain preprocessed radial images and preprocessed axial images; determining an initiation end region, a middle region and a tail region in the preprocessed radial images, dividing a first boundary line between the initiation end region and the middle region, and dividing a second boundary line between the middle region and the tail region; determining the perpendicular distance between the first boundary line and the second boundary line, and multiplying the perpendicular distance by the image magnification ratio of the radial high-speed camera to obtain the height of the middle region; Step 5, preprocessing the radial images and the axial images to obtain preprocessed radial images and preprocessed axial images; determining an initiation end region, a middle region and a tail region in the preprocessed radial images, dividing a first boundary line between the initiation end region and the middle region, and dividing a second boundary line between the middle region and the tail region; determining the perpendicular distance between the first boundary line and the second boundary line, and multiplying the perpendicular distance by the image magnification ratio of the radial high-speed camera to obtain the height of the middle region; Step 6, using the inner diameter, the outer diameter and the height of the middle region of the actual circular ring-shaped particle cloud corresponding to the same collection time as the construction parameters to construct a circular ring body, and calculating the volume of the circular ring body at this time; Step 7, drawing a curve of the volume of the circular ring body changing with time according to the volumes of the circular ring bodies at different times.

[0006] The application also has the following technical features: Specifically, the inert material includes lithium fluoride, calcium carbonate and aluminum trioxide.

[0007] Further, the ratio of the average particle size of the inert material particles to the aluminum powder particles is (0.75-1.25):1.

[0008] Further, when the mass percentage of the mixed particles in the aluminum-containing explosive sample is less than 10%, the mass ratio of the inert material to the aluminum powder is (0.5-1):1; when the mass percentage of the mixed particles in the aluminum-containing explosive sample is 10%-20%, the mass ratio of the inert material to the aluminum powder is (1-3):1; and when the mass percentage of the mixed particles in the aluminum-containing explosive sample is greater than 20%, the mass ratio of the inert material to the aluminum powder is (3-4.5):1.

[0009] Further, the diameter of the expanded explosive column is not less than 10 mm, and the height is not less than 10 mm.

[0010] Further, the optical axis of the axial high-speed camera is coincident with the axis of the aluminum-containing explosive sample.

[0011] Further, the photographing frequency of the axial high-speed camera and the radial high-speed camera is not less than 1x10 5 fps, and the exposure time is 0.5-2 mu s.

[0012] Further, the volume of the annular body is determined by the following formula:

[0013] In the formula, V V is the volume of the annular body, in m3; d max D is the outer diameter of the annular particle cloud, in m; d min D is the inner diameter of the annular particle cloud, in m; h H is the height of the middle region, in m.

[0014] Further, the pretreatment includes gray scale conversion, denoising and image binarization processing.

[0015] Compared with the prior art, the present application has the beneficial technical effects that: (1) The inert material particles and the aluminum powder particles are mixed according to the ratio in the method, on the one hand, the strong light generated by the explosion of the aluminum-containing explosive sample is weakened, so that the distribution of the aluminum powder inside can be observed through the outer surface of the fireball in the simulation test process, on the other hand, a small amount of aluminum powder particles in the aluminum-containing explosive sample provide a suitable brightness illumination source for the shooting of the particle trajectory through the long-time combustion reaction, so that a wide range of particle motion images can be obtained without external auxiliary lighting in the test process.

[0016] (2) The method has simple steps, the outer diameter of the obtained mixed particle cloud is consistent with the diameter of the explosion fireball of the original aluminum-containing explosive sample in spatial variation, so that the two can be directly compared, the test measurement precision is analyzed, and the accuracy of the test result is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a schematic diagram of the explosion test layout of the present application.

[0018] Figure 2 is a high-speed photography image observed from the radial direction at 300 microseconds after initiation in Example 1.

[0019] Figure 3 is a high-speed photography image observed from the axial direction at 300 microseconds after initiation in Example 1.

[0020] Figure 4 is a characteristic size variation curve of the middle region of the mixed particle cloud obtained in Example 1.

[0021] Figure 5 is a schematic diagram of a three-dimensional annular body in which the main distribution region of the mixed particles in Example 1 is located.

[0022] Figure 6 is a volume variation curve of the main distribution region of the mixed particles obtained in Example 1.

[0023] The meanings of various reference numerals in the drawings are as follows: 1 - aluminum-containing explosive sample, 2 - booster, 3 - detonator, 4 - axial high-speed camera, 5 - radial high-speed camera.

[0024] The specific content of the present application is further explained and described in detail in combination with the following examples. DETAILED DESCRIPTION

[0025] It should be noted that all components and raw materials in the present application, if not specially stated, are all known components and raw materials in the prior art.

[0026] The technical concept of the present application is that: in the early stage of the explosion of the aluminum-containing explosive, the aluminum powder particles in the interior do not participate in the reaction and are scattered to a certain space before they burn fiercely and emit strong light, therefore, under the premise that the early detonation driving energy of the aluminum-containing explosive sample is not significantly affected, inert material particles with similar parameters to the aluminum powder particles, such as density, impact impedance kinetic performance (such as gas resistance in the flight process, deformation after impact, etc.), are mixed with the aluminum powder particles to obtain mixed particles, the mixed particles are used to replace the original aluminum powder particles in the aluminum-containing explosive sample, and a cylindrical aluminum-containing explosive sample 1 is prepared; the aluminum-containing explosive sample can moderately weaken the strong light of the aluminum powder particles during the explosion process, and facilitate the clear capture of the scattering and diffusion images of the particle clouds in the explosion field by the high-speed cameras arranged in the axial and radial directions of the aluminum-containing explosive sample; based on the radial images and the axial images, the dynamic distribution space of the aluminum powder particles can be reconstructed, and then the change process of the space volume of the aluminum powder particles with time is determined, key data for the dynamic change of the aluminum powder particle concentration is provided, and thus the technical problem that there is a lack of effective measurement means for the space-time distribution and concentration evolution process of the aluminum powder particles in the explosion field of the aluminum-containing explosive sample is solved, and important technical support is provided for the optimization design of the formula and charging structure of the aluminum-containing explosive sample.

[0027] It should be noted that in the present application, particles and powder are the same concept.

[0028] The aluminum-containing explosive refers to a mixed explosive with fine aluminum powder added in the formula, which includes the following components in mass percentage: 55% to 85% of high-energy elemental explosive (such as TNT, RDX, HMX, etc.), 8% to 35% of aluminum powder, and 2% to 15% of desensitizer / binder, and the mass percentage of each component is 100%.

[0029] The following gives specific embodiments of the present application, and it should be noted that the present application is not limited to the following specific embodiments, and any equivalent transformation made on the basis of the technical solutions of the present application falls within the protection scope of the present application.

[0030] Embodiment 1: According to the above technical solution, as shown in Figures 1 to 6 The present embodiment gives a test method for simulating the diffusion process of aluminum powder in the explosion field of aluminum-containing explosive, which includes the following steps: Step 1, mix the formula amount of inert material particles with aluminum powder particles to obtain mixed particles, replace the aluminum powder particles in the aluminum-containing explosive to be tested with the mixed particles, and prepare a cylindrical aluminum-containing explosive sample 1; In this embodiment, the aluminum-containing explosive to be tested is a pressed aluminum-containing explosive with HMX as the main component. The aluminum-containing explosive sample contains the following components in percentage by mass: 65% of HMX, 30% of mixed particles, and 5% of desensitizer / binder, and in the mixed particles, the mass ratio of inert particles to aluminum powder particles is 4:1. During preparation, first, lithium fluoride particles with an average particle size of 15 μm and aluminum powder particles with an average particle size of 13 μm are mixed in a mass ratio of 4:1 to obtain mixed particles; then the mixed particles are mixed with HMX explosive particles and a binder; finally, a pressed aluminum-containing explosive sample 1 with a mass of 800 g and a size of Φ80 mm×87 mm is prepared by using a pressing process.

[0031] Step 2, an expanding charge column 2 is arranged on the end face of the prepared aluminum-containing explosive sample 1, and a detonator 3 is arranged at the front end of the expanding charge column 2; Preferably, the diameter of the expanding charge column 2 is 25 mm, and the height is 25 mm.

[0032] Step 3, as shown in Figure 1 , the aluminum-containing explosive sample 1 is arranged on a fixed support in the anti-explosion laboratory along the axial direction (horizontally), and the distance between the aluminum-containing explosive sample 1 and the ground is 1.5 m; an axial high-speed camera 4 and a radial high-speed camera 5 are arranged along the axial direction and the radial direction of the aluminum-containing explosive sample 1, respectively, both of which are Kirana 05M high-speed cameras produced by SI Company in the UK, and the optical path of the axial high-speed camera 4 and the optical path of the radial high-speed camera 5 are perpendicular. A length scale with a length of 1 m is arranged at the position of the aluminum-containing explosive sample 1, and the image magnification ratios of the axial high-speed camera 4 and the radial high-speed camera 5 are determined, respectively. L The still images are captured by the axial high-speed camera 4 and the radial high-speed camera 5, respectively, and the length of the length scale in the still images is measured by using existing image processing software, and is recorded as , respectively, so as to calculate the image magnification ratios of the optical path of the axial high-speed camera 4 and the radial high-speed camera 5, and are recorded as and respectively, wherein, , .

[0033] Step 4, the aluminum-containing explosive sample 1 is initiated, and the axial images and radial images of the initiation process of the aluminum-containing explosive sample 1 are collected by the axial high-speed camera 4 and the radial high-speed camera 5, respectively; The parameters of the axial high-speed camera 4 and the radial high-speed camera 5 are set, and in this embodiment, the photographing frequency of the axial high-speed camera 4 and the radial high-speed camera 5 is set to 2×10 5 fps, and the exposure time is set to 1 μs. After all the preparations are completed, the aluminum-containing explosive sample 1 is initiated.

[0034] 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; The preprocessing includes grayscale conversion, denoising, and image binarization.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] The axial images collected by the axial high-speed camera 4 are preprocessed to obtain preprocessed axial images; the inner boundary line and the outer boundary line of the annular particle cloud in the preprocessed axial images are divided, and the inner diameter and the outer diameter of the annular particle cloud in the preprocessed axial images are determined, so as to multiply the determined inner diameter and outer diameter by the image magnification ratio of the axial high-speed camera to obtain the inner diameter and the outer diameter of the actual toroidal particle cloud; As shown in FIG. 4, the black area in the figure is the mixed particles composed of aluminum powder and lithium fluoride. Since Figure 3 there are fewer aluminum powder particles in the initiation end region and the tail region as shown in FIG. 5, the particles in the middle region are mainly distributed in the annular region near the edge of the fireball as shown in FIG. 6, and the annular region is the main distribution region of the mixed particles. Figure 2 Figure 3 The annular ring shown in FIG. 6 is the particle cloud morphology of the middle region, that is, the particle cloud in the middle region is approximately a toroidal body, which also indicates that although the aluminum powder in the aluminum-containing explosive sample 1 is uniformly distributed, the aluminum powder particles are mainly distributed in the annular region near the edge of the fireball during the explosion process of the aluminum-containing explosive sample 1. The inner boundary line and the outer boundary line of the annular particle cloud image are extracted, and then the diameter of the inner boundary and the diameter of the outer boundary are obtained; and the inner diameter and the outer diameter of the actual toroidal particle cloud are determined. The curves of the inner diameter and the outer diameter of the actual toroidal particle cloud in the initiation process of the aluminum-containing explosive sample 1 changing with time are shown in FIG. 7. Figure 4

[0039] Step 6, constructing a toroidal body with the inner diameter, the outer diameter and the height of the middle region of the actual toroidal particle cloud corresponding to the same collection time as the construction parameters, and calculating the volume of the toroidal body at this time; In this embodiment, the structure of the three-dimensional toroidal body in which the mixed particles are mainly distributed is shown in FIG. 8. Figure 5

[0040] Step 7, drawing the curve of the volume of the toroidal body changing with time according to the calculated volumes of the toroidal body at different times.

[0041] Since the concentration of aluminum powder is a key physical quantity affecting its subsequent reaction rate, the focus of studying the diffusion process of aluminum powder is to obtain the change of the volume of its distribution space. Since the mass of aluminum powder is known, the change of its concentration can be calculated after the volume is obtained. The curve of the volume of the toroidal body changing with time drawn in this embodiment is shown in FIG. 9. Figure 6

[0042] ​​​​The preferred embodiments of the present disclosure are described in detail above with reference to the drawings, but the present disclosure is not limited to the specific details in the above-described embodiments. Various simple modifications can be made to the technical solutions of the present disclosure within the technical concept of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

[0043] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, various possible combinations are not described again in the present disclosure.

[0044] In addition, various different embodiments of the present disclosure can also be combined in any appropriate manner, as long as they do not deviate from the idea of the present disclosure, and they should also be considered as disclosed in the present disclosure.

Claims

1. A test method for simulating the process of aluminum powder dispersion in an aluminum-containing explosive blast field, characterized in that, The method comprises the following steps: Step 1, mixing the inert material particles and the aluminum powder particles in a formula amount to obtain mixed particles, and using 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 (1); Step 2, arranging an expanding charge column (2) on the end surface of the prepared aluminum-containing explosive sample (1); Step 3, placing the aluminum-containing explosive sample (1) on a support, arranging a length scale beside the aluminum-containing explosive sample (1), arranging an axial high-speed camera (4) and a radial high-speed camera (5) along the axial and radial directions of the aluminum-containing explosive sample (1), and the optical paths of the axial high-speed camera (4) and the radial high-speed camera (5) are perpendicular to each other; and determining the image magnification ratios of the axial high-speed camera (4) and the radial high-speed camera (5), respectively; Step 4, initiating the aluminum-containing explosive sample (1), and using the axial high-speed camera (4) and the radial high-speed camera (5) to collect axial images and radial images of the initiation process of the aluminum-containing explosive sample (1), respectively; Step 5, preprocessing the radial images and the axial images to obtain preprocessed radial images and preprocessed axial images; determining an initiation end region, a middle region and a tail region in the preprocessed radial images, dividing a first boundary line between the initiation end region and the middle region, and dividing a second boundary line between the middle region and the tail region; determining a vertical distance between the first boundary line and the second boundary line, and multiplying the vertical distance by the image magnification ratio of the radial high-speed camera (5) to obtain a middle region height; preprocessing the axial images collected by the axial high-speed camera (4) to obtain preprocessed axial images; dividing the inner boundary line and the outer boundary line of the annular particle cloud in the preprocessed axial images, and determining the inner diameter and the outer diameter of the annular particle cloud in the preprocessed axial images; and multiplying the determined inner diameter and the outer diameter by the image magnification ratio of the axial high-speed camera (4) to obtain the inner diameter and the outer diameter of the actual annular particle cloud; Step 6, using the inner diameter, the outer diameter and the middle region height of the actual annular particle cloud corresponding to the same collection time as the construction parameters to construct an annular body, and calculating the volume of the annular body at this time; Step 7, drawing a curve of the volume of the annular body changing with time according to the calculated volumes of the annular body at different times.

2. The test method for simulating the process of aluminum powder dispersion in an aluminized explosive blast field according to claim 1, characterized in that, The inert material includes lithium fluoride, calcium carbonate and aluminum oxide.

3. The test method for simulating the process of aluminum powder dispersion in an aluminized explosive blast field according to claim 1, wherein, The ratio of the average particle size of the inert material particles to the average particle size of the aluminum powder particles is (0.75-1.25):

1.

4. The test method for simulating the process of aluminum powder dispersion in an aluminized explosive blast field according to claim 1, wherein, When the mass percentage of the mixed particles in the aluminum-containing explosive sample (1) is less than 10%, the mass ratio of the inert material to the aluminum powder is (0.5-1):1; when the mass percentage of the mixed particles in the aluminum-containing explosive sample (1) is 10%-20%, the mass ratio of the inert material to the aluminum powder is (1-3):1; and when the mass percentage of the mixed particles in the aluminum-containing explosive sample (1) is greater than 20%, the mass ratio of the inert material to the aluminum powder is (3-4.5):

1.

5. The test method for simulating the process of aluminum powder dispersion in an aluminized explosive blast field according to claim 1, wherein, The diameter of the expanding charge column (2) is not less than 10 mm, and the height is not less than 10 mm.

6. The test method for simulating the process of aluminum powder dispersion in an aluminized explosive blast field according to claim 1, wherein, The optical axis of the axial high-speed camera (4) coincides with the axis of the aluminum-containing explosive sample (1).

7. The test method for simulating the process of aluminum powder dispersion in an aluminized explosive blast field according to claim 1, wherein, The axial high-speed camera (4) and the radial high-speed camera (5) have a shooting frequency of not less than 1x10 5 fps and an exposure time of 0.5~2μs.

8. The test method for simulating the process of aluminum powder dispersion in an aluminized explosive blast field according to claim 1, wherein, The volume of the torus is determined by the following formula: In the formula, V V is the volume of the torus, in m3; d max Douter is the outer diameter of the circular ring-shaped particle cloud, in meters; d min Dinner is the inner diameter of the circular ring-shaped particle cloud, in meters; h Hmid is the height of the middle region, in meters.

9. The test method for simulating the process of aluminum powder dispersion in an aluminized explosive blast field according to claim 1, wherein, The preprocessing includes gray scale conversion, denoising and image binarization processing.

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