Experimental device for oil drop impact texture wall surface and method for acquiring dynamic data

Abstract

The invention discloses an experimental device for oil drop impact on a texture wall surface. The experimental device comprises a base platform, a height adjustment system, an oil drop generation system, an experimental plane assembly, an image acquisition system and a data analysis system, the experiment plane assembly is arranged on the base platform and is used for placing a sample on the experiment plane assembly; the height adjusting system is arranged on the base platform and is used for controlling the falling speed of the oil drops; the oil drop generation system is located at the center position over the experiment plane assembly and used for generating oil drops impacting the texture wall surface; the image acquisition system is used for observing the dynamic process that the oil drops impact the texture wall surface in real time; and the data analysis system is used for performing corresponding processing on the acquired image to obtain subsequent specific data. According to the device, the whole movement process is recorded, so that a basis is provided for researching an oil drop adhesion and spreading rule. Meanwhile, the invention further provides a method for obtaining the dynamic data of the oil drop impacting the texture wall surface so as to obtain the related dynamic data.

Description

Technical Field

[0001] The present invention belongs to the field of fluid mechanics and relates to a method for an oil droplet to impact a textured wall surface and obtain related data. Background Art

[0002] The oil lubrication technology is widely used in key design fields related to friction such as machine tool processing, automotive engine component manufacturing, high-speed machining, etc. due to its excellent lubrication and heat dissipation performance. The impact characteristics of oil droplets (such as impact velocity) and the characteristics of solid surfaces (such as surface structure, roughness, etc.) will affect the diffusion dynamic behavior of oil droplets after impacting the solid wall surface to varying degrees, and thus affect functions such as mass transfer, heat transfer, and lubrication. The dynamics of oil droplet impinging on the wall is a complex multiphase flow process, involving interdisciplinary difficult problems such as splash dynamics, multiphase flow, and fluid mechanics. At present, it has been widely used in various industries, but people's basic theoretical research is still not in-depth, and the essence of the process cannot be revealed from a microscopic perspective, which cannot meet the requirements of gradually improving industrial production and equipment development and demand.

[0003] Patent CN118776811A (publication date: October 15, 2024) discloses an experimental device and method for liquid droplets to collide with a moving wall surface, which provides a method for observing the influence of the number, particle size, and velocity of liquid droplets and the angle, velocity, and surface topography of the moving wall surface on the collision of liquid droplets with the moving wall surface. Patent CN115931860A (publication date: April 7, 2023) discloses an observation system for the bouncing behavior of dust-containing liquid droplets impinging on the wall surface, which provides an observation method for the bouncing behavior of dust-containing liquid droplets impinging on the wall surface. The disadvantages of the above two patents are: First, only a method for observing the impingement of liquid droplets on the wall from a single perspective is provided, and the topography of the textured wall surface is complex and diverse, and a single perspective cannot guarantee the comprehensiveness of observation; Second, no method for processing and analyzing the collected data images is provided. The experimental device for oil droplets to impact the textured wall surface and the method for post-processing the collected data are of great significance for lubrication and heat transfer and coating and surface treatment in industrial production applications: For example, in the process of high-pressure air flow transporting lubricating oil to impact the machining tool and the machining textured wall surface, the collision phenomenon between the oil droplets and the wall surface has a significant impact on the lubrication effect and heat transfer efficiency. Therefore, there is an urgent need for an experimental device for oil droplets to impact the textured wall surface and a method for obtaining relevant kinetic data in the whole process. Summary of the Invention

[0004] The problem to be solved by the present invention is to provide an observation device for an oil droplet to impact a textured wall surface, through which the impact of the oil droplet on the textured wall surface is realized and the whole movement process is recorded, so as to provide a basis for studying the laws of oil droplet adhesion and spreading. At the same time, the present invention also provides a method for obtaining the kinetic data of an oil droplet impacting a textured wall surface, which calculates and analyzes the images recorded by the device to obtain relevant kinetic data.

[0005] The experimental device for oil droplets impacting a textured wall surface of the present invention includes a base platform, a height adjustment system, an oil droplet generation system, an experimental plane assembly, an image acquisition system, and a data analysis system; the experimental plane assembly is arranged on the base platform and is used to place a specimen on the experimental plane assembly; the height adjustment system is arranged on the base platform and is used to adjust the oil droplet generation system to the required falling height to control the falling speed of the oil droplets; the oil droplet generation system is located at the central position directly above the experimental plane assembly and is used to generate oil droplets that impact the textured wall surface; the image acquisition system is used to observe the dynamic process of the oil droplets impacting the textured wall surface in real time; the data analysis system is used to perform corresponding processing on the acquired images to obtain subsequent specific data.

[0006] Further, the height adjustment system includes a stepping motor and a lifting frame, and the oil droplet generation system includes a micro-injection pump, a syringe, and an oil droplet control console; the lifting frame is installed on the base platform, and the stepping motor is fixed at the top of the lifting frame; the micro-injection pump is connected to the sliding seat of the lifting frame, the syringe is connected below the micro-injection pump, and the oil droplet control console is fixed on the base platform and is electrically connected to the micro-injection pump.

[0007] Further, the experimental plane assembly includes a lifting optical platform, a specimen, and a hydraulic pump. The specimen is placed on the upper surface of the lifting optical platform and is directly below the syringe, and the hydraulic pump is connected to the lifting optical platform.

[0008] Further, the image acquisition system includes image acquisition units in three directions of X, Y, and Z, and a synchronous trigger button. The image acquisition units in the X and Y directions include a high-speed camera I, a high-speed camera II, a light-emitting diode lamp I, and a light-emitting diode lamp II. The image acquisition unit in the Z direction includes a high-speed camera II and a tripod. The light-emitting diode lamp I and the high-speed camera I are located in front of the lifting optical platform, the light-emitting diode lamp II and the high-speed camera II are located at the left end of the lifting optical platform, the high-speed camera III is placed above the lifting optical platform through the tripod. The lens centers of the high-speed camera I and the high-speed camera II are at the same horizontal height as the surface of the specimen, and the lens center of the high-speed camera III is vertically aligned with the specimen; the synchronous trigger button is electrically connected to the high-speed camera I, the high-speed camera II, and the high-speed camera III; the data analysis system includes a workstation and an Ethernet cable, and the workstation is connected to the three high-speed cameras through the Ethernet cable respectively.

[0009] Further, the oil droplet material in the syringe is silicone oil, and the material of the specimen is tool steel, and its wall surface after cutting has geometrically shaped textures.

[0010] The method for obtaining the dynamic data of oil droplets impacting a textured wall surface in the present invention specifically comprises the following steps: Step 1: Fill the syringe with 1 ml of silicone oil, expel the excess air in the tube, install the syringe on a micro-injection pump, and move the sliding seat of the lifting frame to a suitable position through a stepping motor; Step 2: Adjust the optical lifting platform, adjust the illumination intensity and mode of the light-emitting diode lamp tube, align the positions of the light-emitting diode lamp tube, high-speed camera I and high-speed camera II, and focus on the center of the specimen on the optical lifting platform to form a clearly visible image of the specimen, so as to ensure that a complete and clear motion image can be recorded; Step 3: Use the oil droplet console to adjust the feed rate per second, generate a drop of silicone oil under the syringe, and stop the oil droplet console from working after the oil droplet meets the required volume; Step 4: The sliding seat of the lifting frame slowly slides downward, and is observed by shooting with a high-speed camera III. When the oil droplet is about to contact the specimen on the lifting optical platform at the horizontal position instantaneously, the sliding seat of the lifting frame stops moving, and the focal length of the high-speed camera is adjusted to obtain a clearly visible image; Step 5: When the sliding seat of the lifting frame slowly moves upward to the experimental height, trigger the oil droplet console. During this period, use the synchronous trigger button to make the three high-speed cameras respectively shoot the spreading process along the texture, spreading along the vertical texture and the change process of the overall spreading perspective of the oil droplet impacting the textured wall surface and transmit them to the workstation for storage; Step 6: Use the workstation to identify the images collected by the high-speed cameras and obtain the dynamic parameters of the oil droplet impacting the textured wall surface, including data such as the spreading area S of the oil droplet on the specimen, the rebound height H of the oil droplet, the horizontal movement speed Vx of the oil liquid and the vertical movement speed Vy.

[0011] Among them, Step 5 is specifically as follows: When the sliding seat of the lifting frame moves to different height positions, conduct experiments on the horizontal textured wall surface of the oil droplet impacting the specimen. At this time, the height of the lifting optical platform can be fixed: If it is found that the oil droplet detaches from the specimen and oil droplet splashing occurs when the oil droplet impacts the textured wall surface, then lower the height of the sliding seat for multiple repeated experiments. When the oil droplet does not detach from the specimen and no oil droplet splashing occurs, record the distance between the position of the oil droplet suspended by the syringe and the specimen surface at this time, which is called the critical height h.

[0012] Among them, in Step 6: To obtain the spreading area S between the oil droplet and the wall surface during the process of the oil droplet impacting the textured wall surface, the following steps are included: ① Record the video of the oil droplet falling process, convert the video into images, set the image interval to 0.1 ms, and obtain each frame of picture in the high-speed camera III; ② As Figure 3 shown, based on the black and white pixels of the oil droplet in the photo, calculate the spreading area S of the oil droplet on the textured surface

[0013] Among them, X 1 、X 2 are respectively the pixel coordinates in the horizontal axis direction of the left and right boundaries of the oil droplet in the photo, Y3 , Y 4 are the pixel coordinates of the front and rear boundaries of the oil droplet in the vertical axis direction in the photo, and r is the ratio of the actual length to the unit pixel length.

[0014] Among them, in step six: obtaining the velocities Vx and Vy of the oil droplet in the direction along the texture and perpendicular to the texture after the oil droplet impacts the textured wall surface includes the following steps: ① Recording the video of the oil droplet falling process, converting the video into images, setting the image interval to 0.1 ms, and obtaining each frame of pictures of high-speed camera Ⅰ and high-speed camera Ⅱ; ② Calculating the velocities Vx and Vy of the oil droplet on the specimen in the direction along the texture and perpendicular to the texture at a certain moment according to the pixel positions of the oil droplet in contact with the wall surface in the front and rear two pictures:

[0015]

[0016] Among them, X11 and X12 are the pixel coordinates of the two ends of the bottom of the oil droplet on the specimen in a frame of picture in front of a certain time node of high-speed camera Ⅰ, and X21 and X22 are the pixel coordinates of the two ends of the bottom of the oil droplet on the specimen in a frame of picture behind a certain time node of high-speed camera Ⅰ. Among them, X31 and X32 are the pixel coordinates of the two ends of the bottom of the oil droplet on the specimen in a frame of picture in front of a certain time node of high-speed camera Ⅱ, and X41 and X42 are the pixel coordinates of the two ends of the bottom of the oil droplet on the specimen in a frame of picture behind a certain time node of high-speed camera Ⅱ. r is the ratio of the actual length to the unit pixel length, and f is the sampling frame rate set for the video of the oil droplet impacting the horizontal textured wall surface by the high-speed camera.

[0017] Among them, in step six: obtaining the rebound height H of the oil droplet when the oil droplet impacts the textured wall surface includes the following steps: ① Recording the video of the oil droplet falling process, converting the video into images, setting the image interval to 0.1 ms, and obtaining each frame of pictures; ② Selecting pictures with the same time interval from the continuous pictures; ③ Setting the bit depth of all the pictures in step ②, changing them to 8-bit to obtain images with smaller file sizes, and performing binary processing on the images to obtain black-and-white images, and recording the value of the black pixel points in the black-and-white images as 1 and the value of the white pixel points as 0; ④ Analyzing and processing the black-and-white images: calculating the height H of the oil droplet: H = [Z 顶 -(Z b +Z a )2]×r, where the left bottom contact point and the right bottom contact point of the oil droplet in contact with the specimen wall surface during the movement of the oil droplet are defined as the left end point and the right end point respectively, Za and Zb are the pixel vertical coordinates of the left end point and the right end point respectively, Z top is the pixel vertical coordinate of the vertex of the oil droplet image in the vertical direction, and r is the ratio of the actual length to the unit pixel length.

[0018] The beneficial effects of the device and method of the present invention are as follows: First, the device of the present invention records the whole process of oil droplets impacting different textured walls, and quantitatively studies the morphological evolution process and phase change process of oil droplets impacting different textured walls through the method of the present invention, obtaining data such as the spreading area S of the oil droplets on the specimen, the rebound height H of the oil droplets, and the moving speeds Vx and Vy of the oil droplets in the vertical texture direction and along the texture direction, so as to master the mechanism, critical conditions, change rules, control methods, etc. of oil droplets impacting the textured surface; Second, the device of the present invention adjusts the falling height of the oil droplets through the sliding seat of the lifting frame, controls the position where the oil droplets impact the textured wall by adjusting the position of the specimen on the lifting optical platform, and changes the wetting effect and texture geometry of the wall by replacing textured walls with different morphologies, etc. to simulate different working conditions, and obtains the corresponding kinematic parameters, so as to master the influence of different conditions on the characteristics such as the movement and spreading, rebound behavior, etc. of oil droplets to obtain the change rules; Third, based on three high-speed cameras, the present invention can more accurately study the overall change state of oil droplets in the vertical texture direction, along the texture direction, and from the top-down view angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 FIG. is a perspective view of the experimental device for an oil droplet impacting a textured wall according to the present invention.

[0020] Figure 2 FIG. is a front view of the experimental device for an oil droplet impacting a textured wall according to the present invention.

[0021] Figure 3 FIG. is a schematic diagram of the spreading area of an oil droplet on a textured wall.

[0022] Figure 4 FIG. is a schematic diagram of the rebound height of an oil droplet impacting a textured wall.

[0023] Wherein: 1 - base platform, 2 - lifting frame, 3 - stepping motor, 4 - micro-injection pump, 5 - syringe, 6 - oil droplet control console, 7 - lifting optical platform, 8 - specimen, 9 - hydraulic pump, 10 - high-speed camera I, 11 - workstation, 12 - light-emitting diode lamp I, 13 - oil droplet, 14 - high-speed camera II, 15 - high-speed camera III, 16 - light-emitting diode lamp II, 17 - synchronous trigger button, 18 - tripod. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0025] Embodiment 1

[0026] As Figure 1 、 Figure 2As shown in the figure, the experimental device for oil droplets impacting a textured wall surface of the present invention includes a base platform 1, a height adjustment system, an oil droplet generation system, an experimental plane assembly, an image acquisition system, and a data analysis system; the experimental plane assembly is arranged on the base platform 1 and is used to place a specimen on the experimental plane assembly; the height adjustment system is arranged on the base platform 1 and is used to adjust the oil droplet generation system to the required falling height to control the falling speed of the oil droplets; the oil droplet generation system is located at the center position directly above the experimental plane assembly and is used to generate oil droplets that impact the textured wall surface; the image acquisition system is used to observe the dynamic process of the oil droplets impacting the textured wall surface in real time; the data analysis system is used to perform corresponding processing on the collected images to obtain subsequent specific data.

[0027] Example 2

[0028] As Figure 1 、 Figure 2 As shown in the figure, the experimental device of the present invention: the height adjustment system includes a stepping motor 3 and a lifting frame 2, and the oil droplet generation system includes a micro-injection pump 4, a syringe 5, and an oil droplet control console 6; the lifting frame 2 is installed on the base platform 1, and the stepping motor 3 is fixed at the top of the lifting frame 2; the micro-injection pump 4 is connected to the sliding seat of the lifting frame 2, the syringe 5 is connected below the micro-injection pump 4, and the oil droplet control console 6 is fixed on the base platform 1 and is electrically connected to the micro-injection pump 4.

[0029] When the stepping motor 3 works, the micro-injection pump 4 moves up and down through the sliding seat of the lifting frame 2 to control the distance from the oil droplet to the specimen. The distance change range is 0 - 50 cm, and the corresponding oil droplet speed range is 1 - 2.5 m / s. The oil droplet control console 6 controls the syringe 5 through the micro-injection pump 4 to make the oil droplet impact.

[0030] Example 3

[0031] As Figure 1 、 Figure 2 As shown in the figure, the experimental device of the present invention: the experimental plane assembly includes a lifting optical platform 7, a specimen 8, and a hydraulic pump 9. The specimen 8 is placed on the lifting optical platform 7 and is directly below the syringe 5, and the hydraulic pump 9 is connected to the lifting optical platform 7.

[0032] The hydraulic pump 9 is used to adjust the height of the lifting optical platform 7 so that the specimen 8 is at an appropriate height; the specimen 8 can be replaced with different textured wall surfaces to conduct relevant experiments on the oil droplet 13 impacting the specimen 8.

[0033] Example 4

[0034] As Figure 1 、 Figure 2As shown in the figure, the experimental device of the present invention: The image acquisition system includes image acquisition units in three directions of X, Y, and Z, and a synchronous trigger button 17. The image acquisition units in the X and Y directions include a high-speed camera I 10, a high-speed camera II 14, a light-emitting diode lamp I 12, and a light-emitting diode lamp II 16. The image acquisition unit in the Z direction includes a high-speed camera II 15 and a tripod 18. The light-emitting diode lamp I 12 and the high-speed camera I 10 are located in front of the lifting optical platform 7. The light-emitting diode lamp II 16 and the high-speed camera II 14 are located at the left end of the lifting optical platform 7. The high-speed camera III 15 is placed above the lifting optical platform 7 through the tripod 18. The lens centers of the high-speed camera I 10 and the high-speed camera II 14 are at the same horizontal height as the surface of the specimen 8. The lens center of the high-speed camera III 15 is vertically aligned with the specimen 8. The synchronous trigger button 17 is electrically connected to the high-speed camera I 10, the high-speed camera II 14, and the high-speed camera III 15. The data analysis system includes a workstation 11 and an Ethernet cable. The workstation 11 is connected to the three high-speed cameras through the Ethernet cable respectively.

[0035] Among them, the three high-speed cameras are used to observe the initial position of the oil droplet hitting the textured surface, the movement change of the oil droplet hitting the wall, and the process of the three-way contact line movement of the oil droplet and the wall surface. Their acquisition frequency is 10,000 frames per second, and the image resolution is 1024 pixels × 800 pixels, completely and detailedly recording the short physical phenomenon of the oil droplet hitting the wall surface and spreading on the wall surface. The workstation 11 obtains relevant data through post-processing of the acquired pictures: using image processing software (such as ImageJ software) to process the dynamic parameters of the oil droplet hitting the textured wall surface, including the spreading area S of the oil droplet on the specimen, the rebound height H of the oil droplet, and the movement speeds Vx and Vy of the oil droplet in the vertical texture direction and along the texture direction, etc.

[0036] The hydraulic pump 9 first adjusts the lifting optical platform 7 to a suitable position, then adjusts the focal lengths of the high-speed camera I 10 and the high-speed camera II 14 to form a clear and visible image of the specimen 8, and moves the sliding seat of the lifting frame 2 to a suitable position. Observe the overall view of the oil droplet of the high-speed camera III 15 and adjust the regional position of the oil droplet 13 hitting the specimen 8, and then control the peak and valley points of the oil droplet hitting the texture. Then replace the specimen 8 with different textured wall surfaces to conduct relevant experiments on the oil droplet 13 hitting different specimens 8 on the lifting optical platform 7.

[0037] Example 5

[0038] As Figure 1 、 Figure 2 shown in the figure, the experimental device of the present invention: The oil droplet material in the syringe 5 is silicone oil 13, and the material of the specimen 8 is tool steel, and its wall surface after cutting processing has geometrically shaped textures.

[0039] By replacing different samples, the oil droplets are made to impact the wall with different textures and the corresponding kinematic parameters are obtained.

[0040] Example 6

[0041] The method for obtaining dynamic data of oil droplets impacting a textured wall surface of the present invention comprises the following specific steps: Step 1: Filling a syringe with 1 ml of silicone oil and exhausting excess air in the tube, installing the syringe on a micro-injection pump, and moving the sliding seat of the lifting frame to a suitable position by a stepping motor; Step 2: Adjusting the optical lifting platform, adjusting the illumination intensity and mode of the light-emitting diode lamp, adjusting the positions of the light-emitting diode lamp and high-speed cameras I and II, and focusing on the center of the sample on the optical lifting platform to form a clear and visible image of the sample, so as to ensure that a complete and clear moving image can be recorded; Step 3: Using an oil drop control console to adjust the feed rate per second, generating a drop of silicone oil under the syringe, and stopping the oil drop control console after the oil drop meets the required volume; Step 4: The sliding seat of the lifting frame slowly slides downward, through High-speed camera III is used for observation. When the oil droplet is about to touch the sample on the lifting optical platform in the horizontal position, the sliding seat of the lifting frame stops moving, and the focal length of the high-speed camera is adjusted to obtain a clear and visible image; Step 5. When the sliding seat of the lifting frame slowly moves upward to the experimental height, the oil drop control console is triggered. During this period, the synchronous trigger button is used to make the three high-speed cameras respectively shoot the spreading along the texture, spreading along the vertical texture and the overall spreading perspective change process of the oil droplet hitting the texture wall and transmit them to the workstation for storage; Step 6. The workstation is used to identify the image collected by the high-speed camera to obtain the dynamic parameters of the oil droplet hitting the texture wall, which include the spreading area S of the oil droplet on the sample, the rebound height H of the oil droplet, the horizontal movement speed Vx of the oil and the vertical movement speed Vy.

[0042] Example 7

[0043] The method of the present invention: Step 5 is specifically as follows: when the sliding seat of the lifting frame moves to different height positions, an experiment of oil droplets hitting the horizontal texture wall of the sample is carried out, and the height of the lifting optical platform can be fixed at this time: if the oil droplet hits the texture wall and is found to be separated from the sample and oil droplet splashing occurs, the height of the sliding seat is lowered to carry out multiple repetitive experiments. When the oil droplet does not separate from the sample and oil droplet splashing does not occur, the distance between the position where the syringe suspends the oil droplet and the surface of the sample is recorded at this time and is called the critical height h.

[0044] Example 8

[0045] The method of the present invention: in step 6: obtaining the spreading area S between the oil droplet and the wall surface during the oil droplet impacting the textured wall surface, comprises the following steps: ① recording a video of the oil droplet falling process, converting the video into an image, setting the image interval to 0.1 ms, and obtaining each frame of the image in the high-speed camera III; ② asFigure 3 As shown, based on the black and white pixels of the oil droplet in the photo, the spreading area S of the oil droplet hitting the textured surface is calculated.

[0046] Among them, X 1 , X 2 are respectively the pixel coordinates in the horizontal axis direction of the left and right boundaries of the oil droplet in the photo, Y 3 , Y 4 are respectively the pixel coordinates in the vertical axis direction of the front and rear boundaries of the oil droplet in the photo, and r is the ratio of the actual length to the unit pixel length.

[0047] Example 9

[0048] The method of the present invention: In step six: Obtain the velocities Vx and Vy of the oil droplet in the direction along the texture and perpendicular to the texture after the oil droplet hits the textured wall surface, including the following steps: ① Record the video of the oil droplet falling process, convert the video into images, set the image interval to 0.1 ms, and obtain each frame of pictures of high-speed camera Ⅰ and high-speed camera Ⅱ; ② According to the pixel positions where the oil droplet contacts the wall surface in the front and rear two pictures, calculate the velocities Vx and Vy of the oil droplet on the specimen in the direction along the texture and perpendicular to the texture at a certain moment:

[0049]

[0050] Among them, X11 and X12 are respectively the pixel coordinates of the two ends of the bottom of the oil droplet on the specimen in a frame of picture in front of a certain time node of high-speed camera Ⅰ, and X21 and X22 are respectively the pixel coordinates of the two ends of the bottom of the oil droplet on the specimen in a frame of picture behind a certain time node of high-speed camera Ⅰ. Among them, X31 and X32 are respectively the pixel coordinates of the two ends of the bottom of the oil droplet on the specimen in a frame of picture in front of a certain time node of high-speed camera Ⅱ, and X41 and X42 are respectively the pixel coordinates of the two ends of the bottom of the oil droplet on the specimen in a frame of picture behind a certain time node of high-speed camera Ⅱ. r is the ratio of the actual length to the unit pixel length, and f is the sampling frame rate set for the high-speed camera to shoot the video of the oil droplet hitting the horizontal textured wall surface process.

[0051] Example 10

[0052] Method of the present invention: In step six: obtaining the rebound height H of the oil droplet when it impacts the textured wall surface, including the following steps: ① Recording the video of the oil droplet falling process, converting the video into images, setting the image interval to 0.1 ms, and obtaining each frame of the picture; ② Selecting pictures with the same time interval from the consecutive pictures; ③ Setting the bit depth of all the pictures in step ②, changing it to 8-bit to obtain an image with a smaller file size, and performing binary processing on the image to obtain a black and white image, and recording the value of the black pixel points in the black and white image as 1 and the value of the white pixel points as 0; ④ Analyzing and processing the black and white image: calculating to obtain the oil droplet height H: H = [[Z 顶 -(Z b +Z a )2]×r, where the left bottom contact point and the right bottom contact point where the oil droplet contacts the specimen wall surface during the movement of the oil droplet are respectively defined as the left end point and the right end point, Za and Zb are the pixel vertical coordinates of the left end point and the right end point respectively, Ztop is the pixel vertical coordinate of the vertex of the oil droplet image in the vertical direction, and r is the ratio of the actual length to the unit pixel length.

[0053] The beneficial effects of the device and method of the present invention are as follows: First, the device of the present invention records the whole process of the oil droplet impacting different textured wall surfaces, and quantitatively studies the morphological evolution process and phase change process of the oil droplet impacting different textured wall surfaces through the method of the present invention, obtaining data such as the spreading area S of the oil droplet on the specimen, the rebound height H of the oil droplet, the movement speeds Vx and Vy of the oil droplet in the vertical texture direction and along the texture direction, etc., so as to master the mechanism, critical conditions, change rules, control methods, etc. of the oil droplet impacting the textured surface; Second, the device of the present invention adjusts the falling height of the oil droplet through the sliding seat of the lifting frame, controls the position where the oil droplet impacts the textured wall surface by adjusting the position of the specimen on the lifting optical platform, and changes the wetting effect and texture geometry of the wall surface by replacing different-shaped textured wall surfaces, etc. to simulate different working conditions, and obtains the corresponding kinematic parameters, so as to master the influence of different situations on the characteristics such as the movement and spreading, rebound behavior, etc. of the oil droplet to obtain the change rules; Third, the present invention can more accurately study the overall change state of the oil droplet in the vertical texture direction, along the texture direction, and from the top view angle based on three high-speed cameras.

[0054] In short, the device of the present invention records the complex change process of the oil droplet impacting the textured wall surface, collects and obtains a series of relevant kinematic data, understands the mechanism, critical changes, morphological evolution and control methods of the oil droplet impacting the textured wall surface, and studies the dynamic behavior of the lubricating oil impacting the machining tool and the machining textured wall surface during high-pressure gas transportation, so as to optimize the design of the lubrication system, improve the lubrication efficiency, and reduce energy consumption. Therefore, it has important significance for lubrication and heat transfer, coating and surface treatment in industrial production applications.

[0055] In summary, the above are only the preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. The experimental device for oil droplet impacting a textured wall is characterized by: The apparatus comprises a base platform (1), a height adjustment system, an oil droplet generation system, an experimental plane component, an image acquisition system, and a data analysis system; the experimental plane component is arranged on the base platform (1) and is used to place a sample on the experimental plane component; the height adjustment system is arranged on the base platform (1) and is used to adjust the oil droplet generation system to a required falling height and control the falling speed of the oil droplets; the oil droplet generation system is located at the center position directly above the experimental plane component and is used to generate oil droplets that impact a textured wall surface; the image acquisition system is used to observe in real time the dynamic process of the oil droplets impacting the textured wall surface; and the data analysis system is used to perform corresponding processing on the acquired images to obtain subsequent specific data.

2. The experimental device according to claim 1, characterized in that: The height adjustment system comprises a stepper motor (3) and a lifting frame (2), and the oil droplet generation system comprises a micro-injection pump (4), a syringe (5), and an oil droplet control console (6); the lifting frame (2) is installed on a base platform (1), and the stepper motor (3) is fixed on the top of the lifting frame (2); the micro-injection pump (4) is connected to a sliding seat of the lifting frame (2), the syringe (5) is connected to the bottom of the micro-injection pump (4), and the oil droplet control console (6) is fixed on the base platform (1) and is electrically connected to the micro-injection pump (4).

3. The experimental device according to claim 1, characterized in that: The experimental plane assembly comprises a lifting optical platform (7), a sample (8), and a hydraulic pump (9). The sample (8) is placed on the lifting optical platform (7) and is located directly below the syringe (5). The hydraulic pump (9) is connected to the lifting optical platform (7).

4. The experimental device according to claim 1 is characterized in that: The image acquisition system comprises image acquisition units in three directions of XYZ and a synchronous trigger button (17). The image acquisition unit in the XY direction comprises a high-speed camera I (10), a high-speed camera II (14), a light-emitting diode lamp I (12), and a light-emitting diode lamp II (16). The image acquisition unit in the Z direction comprises a high-speed camera II (15) and a tripod (18). The light-emitting diode lamp I (12) and the high-speed camera I (10) are located in front of the lifting optical platform (7), and the light-emitting diode lamp II (16) and the high-speed camera II1 (4) are located at the left end of the lifting optical platform (7). The high-speed camera III (15) is placed above the lifting optical platform (7) via a tripod (18); the lens centers of the high-speed camera I (10) and the high-speed camera II (14) are at the same horizontal height as the surface of the sample (8); the lens center of the high-speed camera III (15) is vertically aligned with the sample (8); a synchronous trigger button (17) is electrically connected to the high-speed camera I (10), the high-speed camera II (14), and the high-speed camera III (15); and a data analysis system includes a workstation (11) and an Ethernet cable, and the workstation (11) is connected to the three high-speed cameras respectively via the Ethernet cable.

5. The experimental device according to claim 1 is characterized in that: The material of the oil droplets in the syringe (5) is silicone oil (13), and the material of the sample (8) is tool steel, and its wall surface after cutting has a geometric texture.

6. A method for obtaining dynamic data of an oil droplet impacting a textured wall, the specific steps of which are as follows: Step 1: Fill the syringe with 1 ml of silicone oil and expel excess air from the tube, install the syringe on a micro-injection pump, and use a stepper motor to move the sliding seat of the lifting frame to a suitable position; Step 2: Adjust the optical lifting platform, adjust the lighting intensity and mode of the light-emitting diode, adjust the positions of the light-emitting diode and high-speed cameras I and II, focus on the center of the sample on the optical lifting platform to form a clear and visible image of the sample, so as to ensure that a complete and clear moving image can be recorded; Step 3: Use the oil drop console to adjust the feed rate per second to generate a drop of silicone oil under the syringe, and stop the oil drop console after the oil drop meets the required volume; Step 4: The sliding seat of the lifting frame slowly slides downward through High-speed camera III is used for observation. When the oil droplet is about to touch the sample on the lifting optical platform in the horizontal position, the sliding seat of the lifting frame stops moving, and the focal length of the high-speed camera is adjusted to obtain a clear and visible image; Step 5. When the sliding seat of the lifting frame slowly moves upward to the experimental height, the oil drop control console is triggered. During this period, the synchronous trigger button is used to make the three high-speed cameras respectively shoot the spreading along the texture, spreading along the vertical texture and the overall spreading perspective change process of the oil droplet hitting the texture wall and transmit them to the workstation for storage; Step 6. The workstation is used to identify the image collected by the high-speed camera to obtain the dynamic parameters of the oil droplet hitting the texture wall, which include the spreading area S of the oil droplet on the sample, the rebound height H of the oil droplet, the horizontal movement speed Vx of the oil and the vertical movement speed Vy.

7. The method according to claim 6, characterized in that: Step five is as follows: when the sliding seat of the lifting frame moves to different heights, an experiment is carried out in which an oil droplet hits a horizontal textured wall of the sample. At this time, the height of the lifting optical platform can be fixed: if the oil droplet hits the textured wall and is found to be separated from the sample and oil droplet splashing occurs, the height of the sliding seat is lowered to carry out multiple repetitive experiments. When the oil droplet does not separate from the sample and oil droplet splashing does not occur, the distance between the position where the syringe suspends the oil droplet and the sample surface is recorded and is called the critical height h.

8. The method according to claim 6 is characterized in that: in step 6, obtaining the spreading area S between the oil droplet and the wall surface during the process of the oil droplet impacting the textured wall surface comprises the following steps: ① Record the video of the oil drop falling process, convert the video into an image, set the image interval to 0.1ms, and obtain each frame of the picture in the high-speed camera III; ② As shown in Figure 3, based on the black and white pixels of the oil drop in the photo, calculate the spreading area S of the oil drop hitting the texture surface Among them, X1 and X2 are the pixel coordinates of the left and right boundaries of the oil drop in the photo in the horizontal direction, Y3 and Y4 are the pixel coordinates of the front and back boundaries of the oil drop in the photo in the vertical direction, and r is the ratio of the actual length to the unit pixel length.

9. The method according to claim 6, characterized in that: in step 6: obtaining the velocities Vx and Vy of the oil droplet along the texture and perpendicular to the texture after the oil droplet hits the texture wall, comprises the following steps: ① Record the video of the oil drop falling process, convert the video into images, set the image interval to 0.1ms, and obtain each frame of the high-speed camera I and high-speed camera II; ② According to the pixel position of the oil drop in contact with the wall in the previous and next two pictures, calculate the velocity Vx and Vy of the oil drop on the sample along the texture and perpendicular to the texture at a certain moment: Among them, X11 and X12 are the pixel coordinates of the two ends of the bottom of the oil droplet on the sample in a frame of picture before a certain time node of high-speed camera I, and X21 and X22 are the pixel coordinates of the two ends of the bottom of the oil droplet on the sample in a frame of picture after a certain time node of high-speed camera I. Among them, X31 and X32 are the pixel coordinates of the two ends of the bottom of the oil droplet on the sample in a frame of picture before a certain time node of high-speed camera II, and X41 and X42 are the pixel coordinates of the two ends of the bottom of the oil droplet on the sample in a frame of picture after a certain time node of high-speed camera II. r is the ratio of the actual length to the unit pixel length, and f is the sampling frame rate set by the high-speed camera to shoot the video of the oil droplet hitting the horizontal texture wall.

10. The method according to claim 6 is characterized in that: in step 6: obtaining the rebound height H of the oil droplet when the oil droplet hits the textured wall surface, comprises the following steps: ① recording a video of the oil droplet falling process, converting the video into an image, setting the image interval to 0.1 ms, and obtaining each frame of the image; ② selecting images with the same time interval from continuous images; ③ setting the bit depth of all the images in step ② to 8-bit to obtain an image with a smaller file size, and binarizing the image to obtain a black-and-white image, and recording the value of the black pixel in the black-and-white image as 1, and the value of the white pixel as 0; ④ analyzing and processing the black-and-white image: calculating the oil droplet height H: H = [Z 顶 -(Z b +Z a )2]×r, where The left bottom contact point and the right bottom contact point where the oil droplet contacts the sample wall during its movement are defined as the left endpoint and the right endpoint, respectively. Za and Zb are the pixel ordinates of the left endpoint and the right endpoint, respectively. Ztop is the pixel ordinate of the vertex of the oil droplet image in the vertical direction, and r is the ratio of the actual length to the unit pixel length.

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