Method for testing leveling performance of solid propellant slurry

Abstract

The invention relates to a testing method, in particular to a method for testing the leveling performance of solid propellant slurry, which comprises the following steps of: smearing a layer of release agent in a mold, and uniformly filling the solid propellant slurry into the mold; buckling the mold filled with the solid propellant slurry on the test plane, and standing; removing the mold, and acquiring a video of the whole leveling and spreading process of the solid propellant slurry by using a high-speed camera; extracting a video of the whole leveling and spreading process frame by frame, obtaining the vertex position and the diameter of the solid propellant slurry in each frame of image, and establishing a function relationship between the vertex position and the leveling time and a function relationship between the diameter and the leveling time; compared with the prior art, the problem that the leveling process of the chemical slurry is difficult to accurately observe and quantify in the prior art is solved. By means of the method, the leveling performance of the solid propellant slurry is accurately measured so as to be used for analyzing the leveling process and performance, and the method can be used for guiding the pouring process of the solid propellant slurry.

Description

Technical Field

[0001] The present invention relates to a testing method, and more particularly to a testing method for the leveling performance of solid propellant slurry. Background Art

[0002] Solid propellant is a multi-component mixture, and its main components include a prepolymer as the matrix, a plasticizer, a curing agent, as well as an oxidizer and metal fuel particles as the dispersed phase. As the power source material for solid rocket engines, solid propellant plays a crucial role in the fields of national defense and aerospace.

[0003] The leveling performance of the propellant slurry has a crucial impact on its quality and performance in the casting performance. During the casting process of solid propellant, the leveling degree of the slurry will directly affect key performance indicators such as the uniformity, density distribution, and internal structure integrity of the formed propellant grain. However, there are many deficiencies in the current testing methods for the leveling performance of solid propellant slurry. For example, it is difficult to accurately observe and quantify the leveling process of the slurry, resulting in insufficient understanding of its leveling characteristics, and thus unable to effectively guide the setting of process parameters and formulation design during the propellant slurry casting process.

[0004] Therefore, there is an urgent need for a simple and quantifiable testing method for the leveling performance of solid propellant slurry. Summary of the Invention

[0005] The purpose of the present invention is to provide a testing method for the leveling performance of solid propellant slurry to solve at least one of the above problems, so as to solve the problem that it is difficult to accurately observe and quantify the leveling process of the slurry in the prior art. The method of this solution realizes the accurate measurement of the leveling performance of solid propellant slurry for the analysis of the leveling process and performance, and thus can be used to guide the setting of process parameters during the solid propellant slurry casting process.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A testing method for the leveling performance of solid propellant slurry includes the following steps:

[0008] S1: Apply a layer of release agent in the mold, and then evenly fill the solid propellant slurry into the mold coated with the release agent;

[0009] S2: Clamp the mold filled with the solid propellant slurry onto the test plane and let it stand for a period of time to make the solid propellant slurry stable between the mold and the test plane;

[0010] S3: Remove the mold and use a high-speed camera to obtain a video of the entire spreading process of the solid propellant slurry;

[0011] S4: Extract the video of the entire process of the flow spreading of the slurry frame by frame, obtain the vertex positions and diameters of the solid propellant slurry in each frame of the image, and establish the functional relationships between the vertex positions and the flow leveling time as well as between the diameters and the flow leveling time.

[0012] Among them, the adhesion force between the mold release agent and the solid propellant slurry is less than the adhesion force between the test plane and the solid propellant slurry, so that after the solid propellant slurry is inverted on the test plane, it can be smoothly demolded without destroying the stable state of the solid propellant slurry, and thus the test of the flow leveling performance will not be affected.

[0013] Preferably, the mold is a hemispherical PTFE mold, and the hemispherical PTFE mold is: a hemispherical groove is provided on the surface of the PTFE mold.

[0014] Preferably, in the hemispherical PTFE mold, the diameter of the hemispherical groove is 1 - 3 cm, and the thickness of the PTFE mold is 1 - 3 cm; the size of the test plane is 6 - 10 cm × 6 - 10 cm × 2 - 4 mm.

[0015] Preferably, the filling is carried out in batches, and after each addition, the mold is vibrated to make the solid propellant slurry evenly fill the mold to exclude the air bubbles mixed inside the solid propellant slurry.

[0016] Preferably, the mold release agent is dimethyl silicone oil, and the test plane is a stainless steel plate.

[0017] Preferably, the thickness of the coating formed after the mold release agent is applied on the mold surface is 8 - 15 μm.

[0018] Preferably, the standing time is 2 - 10 s to ensure that the solid propellant slurry enters a stable state after being buckled.

[0019] Preferably, the high-speed camera is located on the side of the solid propellant slurry, and the high-speed camera and the solid propellant slurry are set at the same level;

[0020] The field of view of the high-speed camera completely covers the flow leveling area of the entire process of the flow spreading of the solid propellant slurry to completely and accurately capture the entire process of the flow spreading of the solid propellant slurry, and thus accurate data information can be extracted from the video.

[0021] Preferably, the high-speed camera has at least 1920×1080 pixels and at least 30 frames, and is positioned and supported by a tripod.

[0022] Preferably, in step S4, first, each frame of the extracted image is grayscale processed, and then an edge detection algorithm is applied to the grayscale processed image to obtain the vertex positions and diameters of the solid propellant slurry in each frame of the image. Finally, a functional relationship between the vertex positions and diameters varying with the leveling time is obtained through data fitting.

[0023] Preferably, the edge detection algorithm includes the Canny edge detection algorithm, the active contour model, and the Gaussian-Laplacian operator;

[0024] The functional relationship is obtained through function fitting.

[0025] Preferably, the image and video processing in step S4 are both performed in MATLAB.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. High-precision observation: By using a high-resolution high-speed camera to take pictures from a specific angle and combining with the precise image processing function of MATLAB, the minute changes of the slurry during the leveling process can be clearly captured, and accurate vertex and diameter position information can be obtained, thus realizing high-precision observation of the leveling performance of the slurry.

[0028] 2. Quantitative analysis: By collecting and processing data on the shape of the slurry at each moment, a detailed leveling characteristic curve can be plotted, including the variation laws of the vertex height and diameter with time, providing a quantitative evaluation index for the leveling performance of the propellant and helping to deeply understand the leveling mechanism and characteristics of the slurry.

[0029] 3. Good repeatability: The operation steps of the entire research method are clear and standardized, and the molds, materials, and equipment used have good stability and consistency. Therefore, reliable and repeatable experimental results can be obtained in experiments of different batches, providing a solid foundation for the research and development and quality control of the propellant.

[0030] 4. Wide application range: The testing method of the present invention is not only applicable to various types of solid propellant slurries, but also has good applicability to the research on the leveling performance of slurries prepared under different formulations and process conditions, and can provide an effective technical means for the diversified research and development and optimization of the propellant. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a schematic flow diagram of the testing method;

[0032] Figure 2 is a schematic top view of the structure of the mold;

[0033] Figure 3 is a schematic sectional view of the structure of the mold;

[0034] Figure 4 is the initial state of the solid propellant slurry in the application example;

[0035] Figure 5 is the process of the solid propellant slurry flowing and spreading out in the application example;

[0036] Figure 6 is a schematic diagram of a) the image (after grayscale processing) and b) the edge extraction result at a certain frame during the process of the solid propellant slurry flowing and spreading out in the application example;

[0037] Figure 7 is the relationship between the diameter a) and the vertex position b) of solid propellants with different diameters over time in the application example;

[0038] In the figure: 1 - mold; 2 - hemispherical groove. Specific Embodiments

[0039] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0040] Embodiment

[0041] A method for testing the leveling performance of a solid propellant slurry, as Figure 1-3 shown, includes the following steps:

[0042] S1: Apply a layer of release agent in the mold, and then evenly fill the solid propellant slurry into the mold coated with the release agent;

[0043] S2: Clamp the mold filled with the solid propellant slurry onto the test plane and let it stand for a period of time to make the solid propellant slurry stable between the mold and the test plane;

[0044] S3: Remove the mold and use a high - speed camera to obtain a video of the entire process of the solid propellant slurry flowing and spreading out;

[0045] S4: Extract the video of the entire process of flowing and spreading out frame by frame, obtain the vertex position and diameter of the solid propellant slurry in each frame image, and establish a functional relationship between the vertex position and the leveling time and a functional relationship between the diameter and the leveling time;

[0046] Among them, the adhesion force between the release agent and the solid propellant slurry is less than the adhesion force between the test plane and the solid propellant slurry, so that after the solid propellant slurry is inverted onto the test plane, it can be smoothly demolded without destroying the stable state of the solid propellant slurry, and thus does not affect the test of the leveling performance.

[0047] More specifically, in this embodiment:

[0048] 1. Preparation of experimental materials

[0049] Solid propellant slurry: Prepare the solid propellant slurry to be measured, usually requiring its performance to be stable and representative.

[0050] Hemispherical PTFE mold 1: Select a hemispherical PTFE mold 1 with appropriate size and smooth surface. The diameter of the hemispherical groove 2 on the surface of the mold 1 is 2 cm, and the thickness of the mold 1 is 1.5 cm. Ensure that the mold 1 has no defects such as cracks and deformations. This mold 1 has good chemical stability and low surface energy, which can reduce the adhesion force between the slurry and the mold, facilitating subsequent demolding operations.

[0051] Dimethyl silicone oil (release agent): Stir well before use. Since the solid propellant slurry has a high viscosity, evenly applying dimethyl silicone oil on the inner surface of the mold as a release agent can effectively reduce the adhesion force between the slurry and the mold, ensuring that the slurry can maintain its complete shape during the demolding process.

[0052] Stainless steel plate (testing plane): Select a stainless steel plate with a flat surface and high finish, with dimensions of 8 cm × 8 cm × 3 mm; clean and dry it to remove oil stains and impurities on the surface to ensure the adhesion effect between the slurry and the stainless steel plate.

[0053] High-speed camera: Use a camera with high resolution and high-speed shooting function, equipped with appropriate lenses and tripods (selected according to specific test environments and requirements), ensure that the camera can be stably fixed at a position horizontal to the hemispherical slurry, and the shooting field of view can completely cover the leveling area of the slurry.

[0054] Computer and MATLAB software: Prepare a computer with a configuration that meets the running requirements of MATLAB, and install MATLAB software, ensure that relevant functional modules such as the image processing toolbox of the software can be used normally.

[0055] 2. Mold treatment and slurry filling

[0056] Clean the hemispherical PTFE mold, then use a lint-free cloth to dip an appropriate amount of dimethyl silicone oil and evenly apply it on the inner surface of the mold, ensuring that the release agent completely covers the surface of the hemispherical groove and has a uniform thickness, generally controlling the coating thickness at about 10 μm. After coating, place the mold in a dry and clean environment and let it stand for a period of time to allow the release agent to fully infiltrate the mold surface and volatilize the excess solvent to achieve the best demolding effect.

[0057] After the mold is processed, slowly pour the prepared solid propellant slurry into the hemispherical PTFE mold. Add it in small portions at a time and gently vibrate the mold to ensure that the slurry can evenly fill every corner of the mold while avoiding the generation of air bubbles. During the filling process, use tools such as a spatula to scrape the surface of the slurry flat so that it is flush with the edge of the mold, ensuring the consistency and accuracy of the slurry filling volume.

[0058] 3. Mold Assembly and Demolding

[0059] Quickly and accurately place the hemispherical PTFE mold filled with slurry on the pre-prepared stainless steel plate, making the diameter surface of the slurry closely fit the stainless steel plate to ensure there are no gaps and air residues between the two. During the buckling process, pay attention to keeping the mold horizontal and stable to avoid displacement or deformation of the slurry.

[0060] After buckling, place the mold and the stainless steel plate as a whole in an environment with stable temperature and humidity and let it stand for 3 seconds to make the adhesion force between the slurry and the mold and the stainless steel plate reach a stable state. Then, carefully and slowly lift and remove the PTFE mold from the slurry, and observe whether the slurry is demolded completely and adheres to the stainless steel plate. Due to the surface properties of the stainless steel plate, the adhesion force between the slurry and the stainless steel plate is relatively strong, while the adhesion force between the slurry and the contact surface of the mold coated with a release agent is weak, so the slurry can be more easily detached from the mold and can remain on the stainless steel plate for subsequent leveling performance testing.

[0061] If it is found that part of the slurry adheres to the mold or there are cracks, etc., check whether there are problems with the experimental steps and materials and conduct the experiment again.

[0062] 4. Observation and Data Analysis

[0063] Pre-install a camera (at least 1920×1080 pixels, at least 30 frames) at the same horizontal height on one side of the demolded hemispherical slurry according to the predetermined position and angle. Adjust parameters such as the focal length, aperture, and shutter speed of the camera so that it can clearly capture the leveling process of the slurry. Start the camera to record the video before demolding and start the stopwatch to record the leveling time at the same time as demolding. During the leveling process of the slurry, ensure that the environmental conditions are stable to avoid interference from external factors on the leveling of the slurry. The position and shooting parameters of the camera should be accurately calibrated in advance to ensure that the subtle changes of the slurry during the leveling process can be clearly captured.

[0064] After the leveling of the slurry is completed, stop recording the video and transfer the video file to a computer. Open the video file using MATLAB software and process and analyze the video frame by frame. First, convert each frame image of the video into a grayscale image, and then use an edge detection algorithm (such as Canny edge detection, active contour model, or Laplacian of Gaussian) to extract the contour boundary of the slurry, and then determine the vertex position (which can be quantified by establishing a coordinate system) and diameter of the slurry. By processing each frame image, the vertex height and diameter data of the slurry at different times are obtained, and these data are stored in a data file.

[0065] Using the plotting function of MATLAB, plot the data of the vertex height and diameter of the slurry changing with the leveling time during the leveling process of the slurry into a variation curve to visually display the leveling performance law of the slurry. Analyze and fit the obtained curve, and calculate relevant leveling parameters, including leveling rate, radius, etc., so as to comprehensively evaluate, quantitatively analyze, and deeply study the leveling performance of the solid propellant slurry.

[0066] Through the specific operation steps of the above embodiments, the research method for the leveling performance of the propellant slurry of the present invention can be accurately implemented, providing strong technical support and data basis for the research and development and quality control of propellants. In practical applications, the experimental conditions and parameters can be appropriately adjusted and optimized according to different propellant formulations and research requirements to further improve the accuracy and applicability of the research method.

[0067] Application Example

[0068] Test the slurry using the test method given in the application example. The image of the slurry in its initial state (removing the mold) is as Figure 4 shown, and it basically maintains a semi-spherical shape; the changes during the spreading process of the leveling are as Figure 5 shown. Only the images of the slurry states at the 0th, 10th, and 30th seconds are intercepted for display. The entire process of the spreading of the leveling is completely recorded and each frame is extracted during the actual test. It can be seen that during the spreading process of the leveling of the slurry, its vertex height (position) and diameter are constantly changing. Perform grayscale processing on each frame image during the spreading process of the leveling, and perform an edge detection algorithm on it to obtain the changes in the vertex height and diameter in this frame image (taking the center of the slurry as the coordinate origin, then the vertex coordinates only have a change in the y value (longitudinal height), while the diameter only has a change in the x value (horizontal distance)), as Figure 6 shown.

[0069] In this application example, molds with hemispherical grooves having diameters of 1 cm, 1.5 cm, and 2 cm (equivalent to initial diameters of the propellant slurry of 1 cm, 1.5 cm, and 2 cm respectively) were used to test the leveling performance of the solid propellant slurry. The results of the change in its diameter over time and the change in the vertex position over time are as Figure 7 shown. It can be clearly seen from the test results that the leveling process is greatly affected by the initial state of the slurry. Due to the yield behavior of the slurry, the spreading process of large-volume droplets will be faster.

[0070] In summary, the present invention discloses a method for testing the leveling performance of a solid propellant slurry, and the main process is as follows: (1) Take a hemispherical PTFE mold, apply dimethyl silicone oil on the inner surface and then fill it with the solid propellant slurry; (2) Place the mold filled with the slurry on a stainless steel plate and achieve demolding by utilizing the difference in the adhesion force between the slurry and the two; (3) Use a high-speed camera to record the entire process of the slurry leveling; (4) Use MATLAB software to analyze and process the video, read the vertex position and diameter of the slurry, and then obtain the variation laws of the height and diameter of the slurry over time during the leveling process. Compared with the prior art, the present invention can accurately quantify the leveling performance of the solid propellant slurry, and has the advantages of simplicity, high precision, wide application range, etc., providing key technical support for the research on the casting performance of the solid propellant slurry and strong support for the research and production of solid propellants.

[0071] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and all improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A method for testing the leveling performance of solid propellant slurry, characterized in that: The steps include: S1: Apply a layer of release agent in the mold, and then evenly fill the solid propellant slurry into the mold coated with the release agent; S2: Snap the mold filled with solid propellant slurry onto the test plane and let it stand for a while to allow the solid propellant slurry to stabilize between the mold and the test plane; S3: Remove the mold and use a high-speed camera to obtain a video of the entire process of solid propellant slurry leveling and spreading; S4: Extract the video of the whole process of leveling and spreading frame by frame, obtain the vertex position and diameter of the solid propellant slurry in each frame image, and establish the functional relationship between the vertex position and the leveling time and the functional relationship between the diameter and the leveling time; Wherein, the adhesion between the release agent and the solid propellant slurry is smaller than the adhesion between the test plane and the solid propellant slurry.

2. A method for testing the leveling performance of a solid propellant slurry according to claim 1, characterized in that: The mold is a hemispherical PTFE mold, and the hemispherical PTFE mold is: a hemispherical groove is arranged on the surface of the PTFE mold.

3. A method for testing the leveling performance of a solid propellant slurry according to claim 2, characterized in that: In the hemispherical PTFE mold, the diameter of the hemispherical groove is 1-3 cm, and the thickness of the PTFE mold is 1-3 cm; The size of the test plane is 6-10cm×6-10cm×2-4mm.

4. A method for testing the leveling performance of a solid propellant slurry according to claim 1, characterized in that: The filling is carried out in the form of adding in batches, and after each addition, the mold is vibrated to make the solid propellant slurry evenly filled in the mold.

5. The method for testing the leveling performance of a solid propellant slurry according to claim 1, characterized in that: The release agent is dimethyl silicone oil; The test plane is a stainless steel plate.

6. A method for testing the leveling performance of solid propellant slurry according to claim 1, characterized in that: The thickness of the coating formed after the release agent is applied to the surface of the mold is 8-15 μm.

7. A method for testing the leveling performance of solid propellant slurry according to claim 1, characterized in that: The standing time is 2-10s.

8. A method for testing the leveling performance of solid propellant slurry according to claim 1, characterized in that: The high-speed camera is located on the side of the solid propellant slurry, and the high-speed camera and the solid propellant slurry are arranged at the same level; The field of view of the high-speed camera completely covers the leveling area of ​​the solid propellant slurry during the whole leveling and spreading process.

9. A method for testing the leveling performance of solid propellant slurry according to claim 1, characterized in that: In step S4, each frame of the extracted image is firstly gray-scale processed, and then an edge detection algorithm is performed on the gray-scale processed image to obtain the vertex position and diameter of the solid propellant slurry in each frame of the image.

10. A method for testing the leveling performance of solid propellant slurry according to claim 9, characterized in that: The edge detection algorithm includes a Canny edge detection algorithm, an active contour model and a Gaussian-Laplacian operator; The functional relationship is obtained by function fitting.

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