Interference Experimental Device and Method for Droplet Impact on Wall with Microstructure

Abstract

The present invention discloses an interference experimental device and method for a droplet impinging on a wall surface with microstructures, belonging to the technical field of droplet dynamics. The device includes a flexible glass and a glass buckler for supporting the flexible glass. The upper surface of the flexible glass is provided with wall microstructures. Above the flexible glass, a droplet generator is installed, which is used to emit droplets towards the wall microstructures. Corresponding to the wall microstructures, a monochromatic high-speed camera is installed on one side of the flexible glass. Corresponding to the monochromatic high-speed camera, an LED lamp and a metal halide lamp are installed on the other side of the flexible glass. Below the flexible glass, a half-transmissive and half-reflective mirror is installed; the half-transmissive and half-reflective mirror is inclined towards the direction of the metal halide lamp, and the centers of the metal halide lamp and the half-transmissive and half-reflective mirror are on the same horizontal line. Below the half-transmissive and half-reflective mirror, a color high-speed camera is installed. The device and method of the present invention can realize synchronous experiments and measurements on the visualization of millimeter-scale droplets and micron-scale gas film morphologies during the process of a droplet impinging on a wall surface with microstructures.

Description

Technical Field

[0001] The present invention belongs to the technical field of visualization research on droplets and gas films in droplet dynamics, and particularly relates to an interference experimental device and method for a droplet impinging on a wall surface with microstructures. Background Art

[0002] With the continuous development of the deep space exploration field, the payload carried by rocket engines is getting larger and larger, and the gas temperature in the main combustion chamber is also getting higher and higher. During the operation of liquid rocket engines, the high-temperature combustion gas will cause the temperature of the inner wall of the thrust chamber to rise rapidly. In order to prevent the inner wall temperature from being too high and causing a sharp drop in the shell strength, it is necessary to take cooling and heat insulation measures for the inner wall of the thrust chamber. As one of the cooling methods for the inner wall of rocket engine thrust chambers, during the spray cooling process, the atomized liquid droplets wet the wall surface and evaporate after impinging on the wall surface, which can achieve two-phase heat transfer. Therefore, spray cooling has a large heat transfer area and a high convective heat transfer coefficient. Designing and regulating the wall microstructures to improve the spray cooling efficiency is one of the effective means to reduce the inner wall temperature of the engine and achieve stable combustion in the engine.

[0003] During the spray cooling process, the liquid coolant is ejected from a pressurized nozzle and quickly atomized into droplets by the action of air. The spreading, wetting, and evaporation of the droplets after impinging on the wall surface are necessary links for the heat transfer between the droplets and the wall surface. There is still a lack of research on the influence mechanism of wall microstructures on the microscopic flow characteristics of the gas film at the bottom of the droplet, mainly because the gas film is very thin, with a thickness generally in the micron range, and it is difficult to measure experimentally. Understanding the flow characteristics of the gas film at the bottom of the droplet is the basis for regulating the droplet dynamics behavior. By optimizing the wall microstructures, analyzing the flow characteristics of the gas film at the bottom of the droplet, and then regulating the spreading and evaporation behaviors of the droplets to improve the spray cooling efficiency is an important topic in the current multiphase flow research field, and it has important significance for achieving stable combustion in rocket engines and the development of the deep space exploration field.

[0004] However, the existing research mainly analyzes the macroscopic morphology of the droplets during the droplet impinging process, focusing on the influence laws of factors such as droplet size, impinging speed, and droplet physical properties, while the evolution characteristics of the gas film at the bottom of the droplet have not received enough attention. However, in the design of wall microstructures and the study of droplet spreading, the gas film at the bottom of the droplet is particularly important, which can change the droplet dynamics process and has important significance for the spray cooling process. The research on the gas film after the droplet impinges on the wall surface with microstructures is significantly different from the traditional research on the droplet impinging on the wall surface, mainly reflected in aspects such as the contour of the gas film, the internal flow characteristics, and the rupture mechanism. Therefore, it is particularly important to study the process of the droplet impinging on the wall surface with microstructures and measure the micron-scale gas film. It is difficult for the existing technology to analyze the gas film during the process of the droplet impinging on the wall surface with microstructures. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide an interference experiment device and method for a droplet impinging on a wall surface with microstructures, which can realize synchronous experiments and measurements on the visualization of the morphology of millimeter-sized droplets and micron-sized gas films during the process of a droplet impinging on a wall surface with microstructures.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The interference experiment device for a droplet impinging on a wall surface with microstructures disclosed by the present invention includes a flexible glass and a glass buckler for supporting the flexible glass. The upper surface of the flexible glass is provided with wall microstructures. A droplet generator is installed above the flexible glass, and the droplet generator is used to emit droplets towards the wall microstructures. A monochromatic high-speed camera is installed on one side of the flexible glass corresponding to the wall microstructures. An LED lamp and a metal halide lamp are installed on the other side of the flexible glass corresponding to the monochromatic high-speed camera. A semi-transparent and semi-reflective mirror is installed below the flexible glass; the semi-transparent and semi-reflective mirror is inclined towards the direction of the metal halide lamp, and the centers of the metal halide lamp and the semi-transparent and semi-reflective mirror are on the same horizontal line. A color high-speed camera is installed below the semi-transparent and semi-reflective mirror; the glass buckler can change the bending curvature of the flexible glass.

[0008] Furthermore, the glass buckler includes a bottom plate, a plurality of guide rails uniformly distributed on the upper surface of the bottom plate along the circumferential direction of the flexible glass. The guide rails extend along the radial direction of the flexible glass. Sliders are slidably installed on the guide rails. A support plate is fixed on the upper side of the sliders. An adjustable vertical support is installed on the support plate, and the output end of the adjustable vertical support is connected to a clamping member for clamping the flexible glass.

[0009] Furthermore, the clamping member includes a first clamp and a second clamp. The adjustable vertical support includes a first jack and a second jack. The first jack and the second jack are respectively used for providing adjustable support for the first clamp and the second clamp.

[0010] Furthermore, the first clamp includes a first base, a first pressing plate slidably matched with the first base in the vertical direction, and a first locking member for fixing the first pressing plate and the first base. The output end of the first jack is connected to the first base, and a clamping space for the flexible glass is formed between the first pressing plate and the first base.

[0011] Further, the second clamp includes a second base, a second pressing plate slidably engaged with the second base along the vertical direction, and a second locking member for fixing the second pressing plate and the second base. The output end of the second jack is connected to the second base, and a clamping space for the flexible glass is formed between the second pressing plate and the second base with a gap therebetween. The first clamp and the second clamp are located on the same straight line parallel to the radial line of the flexible glass, and the first clamp is located outside the second clamp. Openings are formed on the base and the second pressing plate for making way for the first clamp.

[0012] Further, a hinge seat is fixed on the end face of the support plate towards the center of the flexible glass. The hinge seat is hinged with a rotating cylinder through a connecting rod. The rotating cylinder is rotatably installed at the center of the bottom plate, and the rotating cylinder is connected with a rotation driving device.

[0013] Further, a support is fixed on the lower side of the slider. The support is connected with a hydraulic cylinder. The hydraulic cylinder is installed on the lower side of the bottom plate, and a chute for the cooperation of the support is formed on the bottom plate.

[0014] Further, an air cylinder is installed on the lower side of the bottom plate. The air cylinder is connected with a heating air connecting pipe. Air holes are formed on the bottom plate, and the air cylinder is connected to the air holes through an air pipe.

[0015] Further, the wall micro-structure includes a number of array columns installed on the surface of the flexible glass in an array. The width of the array column is w, the height is h, and the spacing is b. By changing the width w, height h, and spacing b of the array column, the contact angle of the liquid droplet on the wall surface is adjusted, so that the static contact angle range of the liquid droplet on the wall surface of the flexible glass is 5° to 150°.

[0016] Interference experiment method for a droplet impacting a wall with microstructures. Using the interference experiment device described in any of the above, a droplet generator is used to emit droplets towards the wall microstructures. The light emitted by the LED illuminates the entire process of the droplet impacting the wall with microstructures from the side. Subsequently, the light enters a monochromatic high-speed camera to capture the droplet contour of the droplet impacting the wall with microstructures. Then, a custom Matlab program is used to calculate the droplet size and impact velocity of this image. The color high-speed camera is placed vertically. The white light emitted by the metal halide lamp is reflected by a semi-transparent and semi-reflective mirror to the bottom surface of the flexible glass with microstructures. Part of the light is reflected from the bottom surface of the flexible glass with microstructures, and another part of the light passes through the flexible glass with microstructures and then enters the bottom of the droplet and is reflected from the bottom surface of the droplet. The two beams of light reflected from the flexible glass with microstructures and the bottom surface of the droplet interfere to form interference fringes of different colors, pass through the semi-transparent and semi-reflective mirror, and then enter the color high-speed camera. By photographing the interference fringes of the air film at the bottom of the lens, the interference fringes corresponding to the air film thickness are obtained. The interference fringes are subjected to tangential averaging processing, and the air film thickness is calculated according to the lens contour. Then, the interference fringe color is corresponded to the air film thickness. During the process of processing the real air film at the bottom of the droplet, the interference image corresponding to the real air film thickness is converted from the RGB mode to the CIE1976 mode, and its color difference is calculated through the Euclidean distance. A continuous curve can be obtained from the color difference image. This curve is composed of the points with the darkest color. Connecting these dark points can obtain the real thickness of the air film at the bottom of the droplet.

[0017] The beneficial effects of the present invention are as follows:

[0018] The interference experiment device and method for a droplet impacting a wall with microstructures disclosed by the present invention have the following beneficial effects:

[0019] (1) Using white light color interference technology in combination with high-speed photography technology can achieve precise measurement of the morphology of millimeter-scale droplets and micron-scale air films during the process of a droplet impacting a wall with microstructures. By using a glass bender, the bending curvature of the flexible glass can be changed, so that experiments can be carried out under different curvature wall structure conditions.

[0020] (2) By using two-way pulse signals to synchronously trigger the camera, synchronous measurement of millimeter-scale droplets and micron-scale air films during the process of a droplet impacting a wall with microstructures can be achieved.

[0021] (3) By changing the flow characteristics of the air film during the process of a droplet impacting a wall with microstructures, effective regulation of the spray cooling technology in spacecraft thermal control can be achieved.

[0022] Other advantages, objects, and features of the present invention will be set forth in the following description, and to some extent will be obvious to those skilled in the art, or can be learned by those skilled in the art from the practice of the present invention. The objects and other advantages of the present invention can be achieved and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to make the objectives, technical solutions, and beneficial effects of the present invention clearer, the present invention provides the following drawings for illustration:

[0024] Figure 1 It is a schematic structural diagram of the interference experiment device of the present invention;

[0025] Figure 2 It is a schematic structural diagram of the array column of the present invention;

[0026] Figure 3 It is a schematic structural diagram of the glass buckler Figure 1 ;

[0027] Figure 4 It is a schematic structural diagram of the glass buckler Figure 2 ;

[0028] Figure 5 It is an installation schematic diagram of the flexible glass;

[0029] Figure 6 It is a schematic structural diagram of the clamping member;

[0030] Figure 7 It is a schematic structural diagram of the hydraulic cylinder;

[0031] Figure 8 It is an exploded view of the clamping member.

[0032] The reference numerals in the drawings are as follows: droplet generator 1, droplet 2, flexible glass 3, monochromatic high-speed camera 4, LED lamp 5, color high-speed camera 6, metal halide lamp 7, and semi-transmissive semi-reflective mirror 8, glass buckler 9, bottom plate 10, guide rail 11, slider 12, support plate 13, first clamp 14, second clamp 15, first jack 16, second jack 17, first base 18, first pressing plate 19, first locking member 20, second base 21, second pressing plate 22, second locking member 23, opening 24, hinge seat 25, connecting rod 26, rotating cylinder 27, rotation driving device 28, support 29, hydraulic cylinder 30, chute 31, air cylinder 32, heating air connecting pipe 33, air hole 34, air pipe 35. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] As Figures 1 - 8As shown in the figure, the interference experiment device for a droplet 2 hitting a wall surface with microstructures disclosed by the present invention includes a flexible glass 3 and a glass buckler 9 for supporting the flexible glass 3. The flexible glass 3 is made of ultra-white transparent material. The flexible glass 3 serves as the wall surface to be hit to achieve the shooting of the air film at the bottom of the droplet 2 during the impact process of the droplet 2. Water is selected as the working medium for the impact of the droplet 2, and the experimental results with various liquids such as glycerol, silicone oil, and ethanol are compared to analyze the effects of physical property parameters such as the viscosity, density, and surface tension coefficient of the droplet 2 on the spreading and wetting after the impact of the droplet 2.

[0034] The upper surface of the flexible glass 3 is provided with wall microstructures. The shape of the wall microstructures can be selected as needed. In the present invention, the wall microstructures are array-type columns with a micron scale etched on the wall surface of the flexible glass 3 by using photolithography. Above the flexible glass 3, a droplet generator 1 is installed. The droplet generator 1 is used to emit droplets 2 to the wall microstructures. Water is selected as the working medium for the impact of the droplet 2, and the experimental results with various liquids such as glycerol, silicone oil, and ethanol are compared.

[0035] Specifically, a monochromatic high-speed camera 4 is installed on one side of the flexible glass 3 corresponding to the wall microstructures. An LED lamp 5 and a metal halide lamp 7 are installed on the other side of the flexible glass 3 corresponding to the monochromatic high-speed camera 4. A semi-transparent and semi-reflective mirror is installed below the flexible glass 3. The semi-transparent and semi-reflective mirror is inclined towards the direction of the metal halide lamp 7. The centers of the metal halide lamp 7 and the semi-transparent and semi-reflective mirror are on the same horizontal line. A color high-speed camera 6 is installed below the semi-transparent and semi-reflective mirror. The device of the present invention can realize the precise measurement of the millimeter-scale droplet 2 and the micron-scale air film morphology during the process of the droplet 2 hitting the wall surface with microstructures by using white light color interference technology in combination with high-speed photography technology. By means of the glass buckler 9, the bending curvature of the flexible glass 3 can be changed, so that experiments can be carried out under different curvature wall surface structures.

[0036] In the present invention, high-speed photography and white-light color interference means are adopted. The high-speed photography technology is used to photograph the changes in the macroscopic morphology of droplet 2 during the impact process from the side, especially the spreading process of droplet 2. Considering that the impact process of droplet 2 and the evolution process of the micron-scale air film at the bottom of droplet 2 are at different spatial scales, this study intends to achieve synchronous measurement of the impact process of the same droplet 2 from different angles and scales through a synchronous control method. In the experiment, two different optical paths are adopted. One optical path is from the side to observe the change characteristics of the macroscopic morphology of droplet 2 during the impact process of droplet 2. The other optical path is from the bottom, and through a beam-splitting optical path of a semi-transparent and semi-reflective mirror, reflected light is formed at the bottom and the wall surface of droplet 2 to generate interference, and a color high-speed camera 6 is used to photograph the interference fringes, extract the air film contour, and record the evolution process of the micron-scale air film at the bottom of droplet 2. A high-speed camera and a macro lens will be used to photograph the changes in the macroscopic morphology of the side of droplet 2, and a color high-speed camera 6 will be used in cooperation with a semi-transparent and semi-reflective mirror and a long working distance lens to photograph the micron-scale air film at the bottom of droplet 2. The color high-speed camera 6 is vertically placed and on the same axis as the center of droplet 2; the centers of the metal halide lamp 7 and the semi-transparent and semi-reflective mirror are on the same horizontal line, and the semi-transparent and semi-reflective mirror forms a 45-degree angle with the horizontal direction. The two high-speed cameras are synchronously triggered by two pulse signals of the synchronous control device to achieve synchronous photographing of the air film evolution process and the impact process of droplet 2, and experimental data at different scales can be recorded.

[0037] In this embodiment, the glass bender 9 includes a bottom plate 10 and a plurality of guide rails 11 uniformly distributed on the upper surface of the bottom plate 10 along the circumferential direction of the flexible glass 3. The guide rails 11 extend along the radial direction of the flexible glass 3. A slider 12 is slidably installed on the guide rails 11, and the slider 12 can slide along the guide rails 11 to adjust the position of the clamping member in the radial direction. A support plate 13 is fixed on the upper side of the slider 12, and an adjustable vertical support member is installed on the support plate 13. The output end of the adjustable vertical support member is connected to a clamping member for clamping the flexible glass 3, and the adjustable vertical support member can adjust the position of the clamping member in the vertical direction. Through the combination of the slider 12 and the adjustable vertical support member, when their positions change, the bending degree of the flexible glass 3 at its edge can be adjusted, thereby realizing the change of the bending curvature of the flexible glass 3 to meet the needs of different experimental conditions.

[0038] In the embodiment of the present invention, the flexible glass 3 has a circular thin plate structure. There are two bending methods for the flexible glass 3: bending upward and bending downward. When the edge bends upward, the middle part of the flexible glass 3 sinks downward, the outermost end of the flexible glass 3 moves upward, and the slider 12 slides inward along the radial direction, so as to realize the inward extrusion of the flexible glass 3, and the adjustable vertical support member moves upward a certain distance along the vertical direction. Similarly, when the edge bends downward, the middle part of the flexible glass 3 sinks downward, the outermost end of the flexible glass 3 moves downward, and the slider 12 slides inward along the radial direction, so as to realize the inward extrusion of the flexible glass 3, and the adjustable vertical support member moves downward a certain distance along the vertical direction.

[0039] It can be understood that the flexible glass 3 can be bent to a certain extent. If it is necessary to improve the bending conditions of the flexible glass 3, it can be heated to soften it and then bent. As long as the operation is proper, breakage can be avoided, and it can be selected according to actual needs, which can be understood by those skilled in the art.

[0040] In this embodiment, the clamping member includes a first clamp 14 and a second clamp 15, and the adjustable vertical support member includes a first jack 16 and a second jack 17. The first jack 16 and the second jack 17 are respectively used for adjustably supporting the first clamp 14 and the second clamp 15. Through the combination of the two clamps, compared with the single clamping method, stress concentration can be reduced while ensuring the stability of the flexible glass 3 at the clamping position, making the deformation arc of the flexible glass 3 more smooth in the entire radial direction.

[0041] In this embodiment, the first clamp 14 includes a first base 18, a first pressing plate 19 that is slidably matched with the first base 18 along the vertical direction, and a first locking member 20 for fixing the first pressing plate 19 and the first base 18. The output end of the first jack 16 is connected to the first base 18. A clamping space for the flexible glass 3 is formed between the first pressing plate 19 and the first base 18. By adjusting the position of the first pressing plate 19, the clamping degree can be adjusted. The second clamp 15 includes a second base 21, a second pressing plate 22 that is slidably matched with the second base 21 along the vertical direction, and a second locking member 23 for fixing the second pressing plate 22 and the second base 21. The output end of the second jack 17 is connected to the second base 21. A clamping space for the flexible glass 3 is formed between the second pressing plate 22 and the second base 21. The first clamp 14 and the second clamp 15 are located on the same straight line parallel to the radial line of the flexible glass 3, and the first clamp 14 is located outside the second clamp 15. An opening 24 for making way for the first clamp 14 is provided on the base and the second pressing plate 22 to avoid interference between the first clamp 14 and the second clamp 15.

[0042] In the embodiment of the present invention, a vertical guide rod is fixed on the second base 21. The vertical guide rod passes through the hole on the second pressing plate 22, and then the second pressing plate 22 and the second base 21 are fixed by nuts. By adjusting the position of the second pressing plate 22, the clamping degree of the second clamp 15 can be adjusted. By using two clamps, the force bearing can be improved, and the flexible glass 3 can be more easily deformed regularly.

[0043] In this embodiment, a hinge seat 25 is fixed on the end face of the support plate 13 towards the center of the flexible glass 3. The hinge seat 25 is hinged with a rotating cylinder 27 through a connecting rod 26. The rotating cylinder 27 is rotatably installed at the center of the bottom plate 10, and the rotating cylinder 27 is connected with a rotating driving device 28. The rotating driving device 28 includes a gear ring, a gear and a motor. The gear ring is fixed on the outer side of the rotating cylinder 27. The gear ring meshes with the gear, and the gear is driven to rotate by the motor. By adopting the rotating cylinder 27, the sliding adjustment of each support plate 13 can be unified, and the radial distance can be controlled uniformly.

[0044] As a further improvement of the embodiment of the present invention, a support 29 is fixed on the lower side of the slider 12. The support 29 is connected with a hydraulic cylinder 30. The hydraulic cylinder 30 is installed on the lower side of the bottom plate 10. A chute 31 for the cooperation of the support 29 is provided on the bottom plate 10. By separately matching the slider 12 with the hydraulic cylinder 30, the position of the slider 12 can be finely adjusted to meet the needs of the change of the radial position at different positions, and the uniformity of the deformation of the flexible glass 3 in the circumferential direction can be ensured.

[0045] In this embodiment, an air cylinder 32 is installed on the lower side of the bottom plate 10. The air cylinder 32 is connected with a heating air connecting pipe 33. An air hole 34 is provided on the bottom plate 10. The air cylinder 32 is connected to the air hole 34 through an air pipe 35. By adopting the air hole 34, hot air can be sprayed onto the flexible glass 3, which is beneficial to the deformation of the flexible glass 3. In order to maintain a relatively low heating temperature and extend the heating time while ensuring the wall structure, it can be selected according to needs.

[0046] In this embodiment, the wall micro-structure includes a number of array columns arranged on the surface of the flexible glass 3. The array columns with micron scale are etched on the wall surface by using micro-lithography. The width of the array column is w, the height is h, and the spacing is b. By changing the width w, height h and spacing b of the array column, the contact angle of the liquid droplet 2 on the wall surface can be adjusted, so that the static contact angle range of the liquid droplet 2 on the wall surface of the flexible glass 3 is 5~150°.

[0047] Interference experiment method for a droplet 2 impinging on a wall surface with microstructures. Using the interference experiment device as described in any of the above, a droplet generator 1 is used to emit a droplet 2 towards the wall microstructures. The light emitted by an LED lamp 5 illuminates the entire process of the droplet 2 impinging on the wall surface with microstructures from the side. Subsequently, the light enters a monochromatic high-speed camera 4, and the contour of the droplet 2 impinging on the wall surface with microstructures is photographed. Then, a custom Matlab program is used to calculate the size and impact velocity of the droplet 2 in this image. A color high-speed camera 6 is placed vertically. The white light emitted by a metal halide lamp 7 is reflected onto the bottom surface of a flexible glass 3 with microstructures after passing through a semi-transparent and semi-reflective mirror. Part of the light is reflected from the bottom surface of the flexible glass 3 with microstructures, and another part of the light passes through the flexible glass 3 with microstructures and then enters the bottom of the droplet 2 and is reflected from the bottom surface of the droplet 2. The two beams of light reflected from the flexible glass 3 with microstructures and the bottom surface of the droplet 2 interfere to form interference fringes of different colors, pass through the semi-transparent and semi-reflective mirror, and then enter the color high-speed camera 6. By photographing the interference fringes of the air film at the bottom of the lens, the interference fringes corresponding to the air film thickness are obtained. The interference fringes are subjected to tangential averaging processing, and the air film thickness is calculated based on the lens contour. Then, the interference fringe colors are corresponded to the air film thickness. During the processing of the real air film at the bottom of the droplet 2, the interference image corresponding to the real air film thickness is converted from the RGB mode to the CIE1976 mode, and its color difference is calculated through the Euclidean distance. A continuous curve can be obtained from the color difference image. This curve is composed of the points with the darkest colors. Connecting these dark points can obtain the real thickness of the air film at the bottom of the droplet 2.

[0048] An experimental device proposed by the present invention can simultaneously obtain the macroscopic contour of a millimeter-scale droplet 2 and the microscopic morphology of a micron-scale air film during the process of the droplet 2 impinging on a wall surface with microstructures. It can realize the experimental measurement of the millimeter-scale droplet 2 and the micron-scale air film at different time and space scales, obtain the conversion law of the flow state inside the air film, reveal the discharge and rupture mechanism of the air film at the bottom of the droplet 2, and finally realize the regulation of spreading and wetting during the droplet 2 impact process. The invention of this experimental device will further enrich and improve the existing droplet 2 impact theory, deepen the understanding of the evolution characteristics of the bottom air film during the process of the droplet 2 impinging on a wall surface with microstructures, and finally provide theoretical guidance for the application of spray cooling technology in spacecraft thermal control.

[0049] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not restrictive. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. Interference experimental device for droplet impact on microstructured wall, characterized by: The invention comprises flexible glass and a glass bender for supporting the flexible glass, wherein a wall microstructure is arranged on the upper surface of the flexible glass, a droplet generator is installed above the flexible glass, and the droplet generator is used to emit droplets to the wall microstructure, a monochrome high-speed camera is installed on one side of the flexible glass corresponding to the wall microstructure, an LED lamp and a metal halide lamp are installed on the other side of the flexible glass corresponding to the monochrome high-speed camera, and a semi-transparent and semi-reflective mirror is installed below the flexible glass; the semi-transparent and semi-reflective mirror is arranged to be inclined toward the direction of the metal halide lamp, and the The centers of the metal halide lamp and the semi-transparent and semi-reflective mirror are on the same horizontal line, and a color high-speed camera is installed below the semi-transparent and semi-reflective mirror; the glass bender can change the bending curvature of the flexible glass; the glass bender includes a bottom plate, and a plurality of guide rails uniformly distributed on the upper surface of the bottom plate along the circumference of the flexible glass, the guide rails extend along the radial direction of the flexible glass, a slider is slidably installed on the guide rail, a support plate is fixed on the upper side of the slider, an adjustable vertical support member is installed on the support plate, and the output end of the adjustable vertical support member is connected to a clamp for clamping the flexible glass The invention relates to a clamping member for tightening the glass. The clamping member comprises a first clamp and a second clamp, and the adjustable vertical support comprises a first jack and a second jack, wherein the first jack and the second jack are respectively used for adjustably supporting the first clamp and the second clamp; the first clamp comprises a first base, a first pressing plate which is matched with the first base along the vertical sliding direction, and a first locking member which is used to fix the first pressing plate and the first base, and the output end of the first jack is connected to the first base, and a clamping space for flexible glass is formed between the first pressing plate and the first base; the second clamp comprises a second base, a second pressing plate which is matched with the second base along the vertical sliding direction, and a second locking member which is used to fix the second pressing plate and the second base, and the output end of the second jack is connected to the second base, and a clamping space for flexible glass is formed between the second pressing plate and the second base; the first clamp and the second clamp are located on the same straight line parallel to the radial line of the flexible glass, and the first clamp is located on the outside of the second clamp, and the base and the second pressing plate are provided with openings which are used to make way for the first clamp.

2. The interference experimental device of droplet impacting a microstructured wall according to claim 1, characterized in that: A hinge seat is fixed on the end surface of the support plate facing the center of the flexible glass. The hinge seat is hinged with a rotating drum through a connecting rod. The rotating drum is rotatably installed at the center of the bottom plate and is connected to a rotating drive device.

3. The interference experimental device of droplet impacting a microstructured wall according to claim 2, characterized in that: A support is fixed on the lower side of the sliding block, the support is connected to a hydraulic cylinder, the hydraulic cylinder is installed on the lower side of a bottom plate, and a sliding groove for the support to cooperate is opened on the bottom plate.

4. The interference experimental device for droplet impacting a microstructured wall according to any one of claims 1 to 3, characterized in that: An air cylinder is installed on the lower side of the bottom plate, and the air cylinder is connected to a heating air connecting pipe. An air hole is opened on the bottom plate, and the air cylinder is connected to the air hole through an air pipe.

5. The interference experimental device of droplet impacting a microstructured wall according to claim 1, characterized in that: The wall microstructure includes a plurality of array columns installed on the flexible glass surface, wherein the width of the array columns is w, the height is h, and the spacing is b. The contact angle of the droplet on the wall is adjusted by changing the width w, height h, and spacing b of the array columns, so that the static contact angle of the droplet on the flexible glass wall is in the range of 5 to 150°.

6. Interference experimental method of droplet impacting a microstructured wall, characterized by: An interference experiment device as described in any one of claims 1 to 5 is used, a droplet generator is used to emit droplets to the wall microstructure, the light emitted by the LED lamp illuminates the entire process of the droplet impacting the wall with the microstructure from the side, and then the light is emitted into a monochrome high-speed camera to capture the droplet contour of the droplet impacting the wall with the microstructure; then, a custom Matlab program is used to calculate the droplet size and impact speed of the image; the color high-speed camera is placed vertically, and the white light emitted by the metal halide lamp is reflected to the bottom surface of the flexible glass with the microstructure after passing through a semi-transparent and semi-reflective mirror, a part of the light is reflected from the bottom surface of the flexible glass with the microstructure, and the other part of the light passes through the flexible glass with the microstructure and is incident on the bottom of the droplet and is reflected from the bottom surface of the droplet; The two beams of light reflected from the surface interfere to form interference fringes of different colors, which pass through the semi-transparent and semi-reflective mirror and then enter the color high-speed camera. The interference fringes of the air film at the bottom of the semi-transparent and semi-reflective mirror are obtained by shooting, and the interference fringes corresponding to the thickness of the air film are obtained. The interference fringes are tangentially averaged, and the thickness of the air film is calculated according to the contour of the semi-transparent and semi-reflective mirror. Then, the color of the interference fringes is matched with the thickness of the air film. In the process of processing the air film at the bottom of the droplet, the interference image of the air film thickness is converted from the RGB mode to the CIE1976 mode, and the color difference is calculated by the Euclidean distance. From the color difference image, a continuous curve can be obtained, which is composed of the darkest points. By connecting these dark points, the true thickness of the air film at the bottom of the droplet can be obtained.

Images