Interference experiment device and method for impact of liquid drops on wall surface with microstructure

Abstract

The invention discloses an interference experiment device and method for impact of liquid drops on a wall surface with a microstructure, and belongs to the technical field of liquid drop kinetics, the device comprises flexible glass and a glass buckling device used for supporting the flexible glass, the upper surface of the flexible glass is provided with a wall surface microstructure, a liquid drop generator is installed above the flexible glass, and the wall surface microstructure is arranged on the wall surface of the flexible glass. The liquid drop generator is used for emitting liquid drops to the wall surface microstructure, a single-color high-speed camera is mounted on one side, corresponding to the wall surface microstructure, of the flexible glass, an LED lamp and a metal halide lamp are mounted on the other side, corresponding to the single-color high-speed camera, of the flexible glass, and a semi-transparent and semi-reflecting mirror is mounted below the flexible glass; the semi-transparent and semi-reflective mirror is obliquely arranged towards the direction of the metal halide lamp, the center of the metal halide lamp and the center of the semi-transparent and semi-reflective mirror are located on the same horizontal line, and a color high-speed camera is installed below the semi-transparent and semi-reflective mirror. According to the device and the method disclosed by the invention, the visual synchronous experiment and measurement of the shapes of the millimeter-sized liquid drops and the micron-sized gas film in the process that the liquid drops impact the wall surface with the microstructure can be realized.

Description

Technical Field

[0001] The invention belongs to the technical field of visualization research of droplets and air films in droplet dynamics, and in particular relates to an interference experimental device and method for droplets impacting a wall surface with a microstructure. Background Art

[0002] With the continuous development of deep space exploration, the load carried by rocket engines is getting larger and larger, and the gas temperature in the main combustion chamber is getting higher and higher. During the operation of liquid rocket engines, high-temperature combustion gas will rapidly increase the temperature of the thrust chamber wall. In order to prevent the inner wall temperature from being too high and causing the shell strength to drop sharply, cooling and insulation measures need to be taken for the thrust chamber inner wall. Spray cooling is one of the cooling methods for the thrust chamber inner wall of a rocket engine. During the spraying process, the atomized droplets hit the wall surface, wet the wall surface and evaporate, which can realize two-phase heat exchange. Therefore, spray cooling has a large heat exchange area and a high convective heat transfer coefficient. Improving the efficiency of spray cooling by designing and regulating the wall microstructure is one of the effective means to reduce the temperature of the engine inner wall and achieve stable combustion in the engine.

[0003] During the spray cooling process, the liquid coolant is sprayed from the pressurized nozzle and reacts with the air to quickly atomize into droplets. The spreading, wetting and evaporation of the droplets after hitting the wall are necessary links in the heat exchange between the droplets and the wall. There are still deficiencies in the study of the influence of the wall microstructure on the microscopic flow characteristics of the air film at the bottom of the droplets. This is mainly reflected in the fact that the air film is very thin, and its thickness is generally in the micron level, which makes experimental measurement difficult. Clarifying the flow characteristics of the air film at the bottom of the droplet is the basis for regulating the dynamic behavior of the droplet. Improving the efficiency of spray cooling by optimizing the wall microstructure, analyzing the flow characteristics of the air film at the bottom of the droplet, and then regulating the spreading and evaporation behavior of the droplets is an important topic in the current multiphase flow research field, which is of great significance to achieving stable combustion in rocket engines and the development of deep space exploration.

[0004] However, existing research mainly analyzes the macroscopic morphology of droplets during droplet impact, focusing on the influence of factors such as droplet size, impact velocity and droplet physical properties, while the evolution characteristics of the air film at the bottom of the droplet have not received enough attention. However, in the design of wall microstructures and droplet spreading research, the air film at the bottom of the droplet is particularly important. It can change the dynamic process of the droplet and is of great significance to the spray cooling process. There are obvious differences between the study of air film after droplets impact on microstructured walls and traditional research on droplet impact on walls, mainly reflected in the contour of the air film, internal flow characteristics and rupture mechanism. Therefore, the process of droplets impacting microstructured walls and the measurement of micron-level air films are particularly important. It is difficult to analyze the air film during the process of droplets impacting microstructured walls with existing technologies. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide an interference experimental device and method for droplets impacting a wall with a microstructure, which can realize synchronous experiments and measurements of the visualized morphology of millimeter-scale droplets and micrometer-scale air films in the process of droplets impacting a wall with a microstructure.

[0006] In order to achieve the above object, the present invention provides the following technical solutions: The invention discloses an interference experiment device for droplets impacting a wall surface with a microstructure, comprising a flexible glass and a glass bender for supporting the flexible glass, wherein the upper surface of the flexible glass is provided with a wall surface microstructure, a droplet generator is installed above the flexible glass, and the droplet generator is used to emit droplets toward the wall surface microstructure, a monochrome high-speed camera is installed on one side of the flexible glass corresponding to the wall surface 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 tilted toward the direction of the metal halide lamp, 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.

[0007] Furthermore, the glass bender includes a base plate and a plurality of guide rails uniformly distributed on the upper surface of the base plate along the circumference of the flexible glass, the guide rails extending along the radial direction of the flexible glass, a slider slidably mounted on the guide rails, a support plate fixed on the upper side of the slider, an adjustable vertical support member mounted on the support plate, and a clamping member for clamping the flexible glass connected to the output end of the adjustable vertical support member.

[0008] Further, the clamping member includes a first clamp and a second clamp, and the adjustable vertical support member includes a first jack and a second jack, and the first jack and the second jack are used to adjustably support the first clamp and the second clamp, respectively.

[0009] Furthermore, the first clamp includes a first base, a first pressure plate that vertically slides with the first base, and a first locking member for fixing the first pressure plate and the first base. 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 pressure plate and the first base.

[0010] Furthermore, the second clamp includes a second base, a second pressure plate vertically slidingly matched with the second base, and a second locking member for fixing the second pressure plate and the second base, the output end of the second jack is connected to the second base, and the second pressure plate and the second base are separated to form a clamping space for the flexible glass; 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 pressure plate are provided with openings for making way for the first clamp.

[0011] Furthermore, 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 the rotating drum is connected to a rotation driving device.

[0012] Furthermore, 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 base plate, and a sliding groove for the support to cooperate is opened on the base plate.

[0013] Furthermore, an air cylinder is installed on the lower side of the bottom plate, 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.

[0014] Furthermore, the wall microstructure includes a plurality of array columns installed in an array on the surface of a flexible glass, 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°.

[0015] An interference experiment method for droplet impacting a wall surface with a microstructure, using an interference experiment device as described in any of the above items, a droplet generator is used to emit droplets to the wall microstructure, the light emitted by an LED lamp illuminates the entire process of the droplet impacting the wall surface with the microstructure from the side, and then the light is emitted into a monochrome high-speed camera to capture the droplet profile of the droplet impacting the wall surface 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 glass and the bottom of the droplet interfere to form interference fringes of different colors, which pass through a semi-transparent and semi-reflective mirror and then enter a color high-speed camera. The interference fringes of the air film at the bottom of the lens are obtained by photographing, 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 based on the lens profile. Then, the color of the interference fringes is matched with the thickness of the air film. In the process of processing the real air film at the bottom of the droplet, the interference image with the real 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 real thickness of the air film at the bottom of the droplet can be obtained.

[0016] The beneficial effects of the present invention are: The interference experimental device and method of droplet impacting a wall with a microstructure disclosed in the present invention have the following beneficial effects: (1) The use of white light color interferometry combined with high-speed photography technology can achieve precise measurement of the millimeter-scale droplet and micrometer-scale air film morphology during the process of droplet impacting a microstructured wall. The curvature of the flexible glass can be changed by using a glass bender, so that experiments can be carried out under conditions of different curvature wall structures.

[0017] (2) The two-way pulse signal is used to synchronously trigger the camera, which can realize the synchronous measurement of millimeter-scale droplets and micrometer-scale air films when the droplets impact the wall with microstructures.

[0018] (3) By changing the flow characteristics of the air film during the impact of droplets on the microstructured wall, the spray cooling technology in the thermal control of spacecraft can be effectively controlled.

[0019] Other advantages, objectives and features of the present invention will be described in the following description and will be apparent to those skilled in the art to some extent, or those skilled in the art may be taught from the practice of the present invention. The objectives and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to make the purpose, technical solution and beneficial effects of the present invention clearer, the present invention provides the following drawings for illustration: Figure 1 It is a structural schematic diagram of the interference experimental device of the present invention; Figure 2 It is a structural schematic diagram of the array column of the present invention; Figure 3 Schematic diagram of the structure of the glass bender Figure 1 ; Figure 4 Schematic diagram of the structure of the glass bender Figure 2 ; Figure 5 This is a schematic diagram of the installation of flexible glass; Figure 6 is a schematic diagram of the structure of the clamping member; Figure 7 It is a structural schematic diagram of a hydraulic cylinder; Figure 8 Exploded view of the clamp.

[0021] The markings in the accompanying drawings are as follows: droplet generator 1, droplet 2, flexible glass 3, monochrome high-speed camera 4, LED lamp 5, color high-speed camera 6, metal halide lamp 7, and semi-transparent and semi-reflective mirror 8, glass bender 9, base 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 pressure plate 19, first locking member 20, second base 21, second pressure plate 22, second locking member 23, opening 24, hinged seat 25, connecting rod 26, rotating drum 27, rotating drive device 28, support 29, hydraulic cylinder 30, slide 31, air cylinder 32, heating gas connecting pipe 33, air hole 34, air pipe 35. DETAILED DESCRIPTION

[0022] like Figures 1 to 8As shown, the interference experimental device for a droplet 2 impacting a wall with a microstructure disclosed in the present invention comprises a flexible glass 3 and a glass bender 9 for supporting the flexible glass 3. The flexible glass 3 is made of an ultra-white transparent material and serves as a wall surface to be impacted, so as to realize the shooting of the air film at the bottom of the droplet 2 during the impact of the droplet 2. Water is selected as the working fluid for the impact of the droplet 2, and the experimental results of various liquids such as glycerol, silicone oil and ethanol are compared to analyze the influence of physical parameters such as viscosity, density and surface tension coefficient of the droplet 2 on the spreading and wetting of the droplet 2 after impact.

[0023] The upper surface of the flexible glass 3 is provided with a wall microstructure, and the shape of the wall microstructure can be selected as needed. The wall microstructure of the present invention is an array of micrometer-scale columns etched on the wall of the flexible glass 3 by microlithography. A droplet generator 1 is installed above the flexible glass 3, and the droplet generator 1 is used to emit droplets 2 to the wall microstructure. Water is selected as the working medium for the droplet 2 to hit, and the experimental results are compared with those of various liquids such as glycerol, silicone oil and ethanol.

[0024] Specifically, a monochrome high-speed camera 4 is installed on one side of the flexible glass 3 corresponding to the wall microstructure, an LED lamp 5 and a metal halide lamp 7 are installed on the other side of the flexible glass 3 corresponding to the monochrome high-speed camera 4, and a semi-transparent and semi-reflective mirror is installed below the flexible glass 3; the semi-transparent and semi-reflective mirror is tilted toward 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, and a color high-speed camera 6 is installed below the semi-transparent and semi-reflective mirror. The device of the present invention uses white light color interference technology in combination with high-speed photography technology to achieve precise measurement of millimeter-level droplets 2 and micrometer-level air film morphology during the process of droplets 2 impacting a wall with a microstructure. The bending curvature of the flexible glass 3 can be changed by a glass bender 9, so that experiments can be carried out under conditions of wall structures with different curvatures.

[0025] In the present invention, high-speed photography and white light color interference are used to shoot the changes in the macroscopic morphology of the droplet 2 during the impact of the droplet 2 from the side, especially the spreading process of the droplet 2. In view of the fact that the impact process of the droplet 2 and the evolution process of the micron-scale air film at the bottom of the 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. Two different optical paths are used in the experiment. One optical path is used from the side to observe the macroscopic morphological change characteristics of the droplet 2 during the impact of the droplet 2, and the other optical path is used from the bottom through a semi-transparent and semi-reflective mirror to split the optical path, forming reflected light and interference at the bottom and wall of the droplet 2, and the interference fringes are photographed by a color high-speed camera 6, the air film contour is extracted, and the evolution process of the micron-scale air film at the bottom of the droplet 2 is recorded. A high-speed camera and a macro lens will be used to shoot the macroscopic morphological changes on the side of the droplet 2, and a color high-speed camera 6 will be used in conjunction with a semi-transparent and semi-reflective mirror and a long working distance lens to shoot the micron-scale air film at the bottom of the droplet 2. The color high-speed camera 6 is placed vertically and on the same axis as the center of the 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 is at a 45-degree angle to the horizontal direction. The two high-speed cameras are synchronously triggered by two pulse signals from the synchronous control device to achieve synchronous shooting of the air film evolution process and the droplet 2 impact process, and can record experimental data at different scales.

[0026] In this embodiment, the glass bender 9 includes a base plate 10, a plurality of guide rails 11 uniformly distributed on the upper surface of the base plate 10 along the circumference of the flexible glass 3, the guide rails 11 extending along the radial direction of the flexible glass 3, and a slider 12 slidably mounted on the guide rails 11, and the slider 12 can slide along the guide rails 11 to adjust the radial position of the clamping member. A support plate 13 is fixed on the upper side of the slider 12, and an adjustable vertical support member is mounted on the support plate 13, and a clamping member for clamping the flexible glass 3 is connected to the output end of the adjustable vertical support member, and the adjustable vertical support member can adjust the vertical position of the clamping member. Through the combination of the slider 12 and the adjustable vertical support member, when the positions of the two change, the bending degree of the flexible glass 3 at its edge can be adjusted, thereby achieving a change in the bending curvature of the flexible glass 3 to meet the needs of different experimental conditions.

[0027] In the embodiment of the present invention, the flexible glass 3 is a circular thin plate structure, and the flexible glass 3 has two bending modes, upward bending and downward bending. When the edge bends upward, the middle of the flexible glass 3 is sunken downward, the outermost end of the flexible glass 3 is displaced upward, and the slider 12 slides radially inward, thereby achieving inward extrusion of the flexible glass 3, and the adjustable vertical support member moves a distance upward in the vertical direction. Similarly, when the edge bends downward, the middle of the flexible glass 3 is sunken downward, the outermost end of the flexible glass 3 is displaced downward, and the slider 12 slides radially inward, thereby achieving inward extrusion of the flexible glass 3, and the adjustable vertical support member moves a distance downward in the vertical direction.

[0028] It is understandable that the flexible glass 3 can be bent to a certain extent. If the bending condition of the flexible glass 3 needs to be improved, it can be heated to soften it and then bent. As long as the operation is proper, breakage can be avoided. The selection can be made according to actual needs, which can be understood by technical personnel in this field.

[0029] 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, and the first jack 16 and the second jack 17 are respectively used to adjustably support the first clamp 14 and the second clamp 15. Compared with a single clamping method, the combination of the two clamps can reduce stress concentration while ensuring the stability of the flexible glass 3 in the clamping position, so that the deformation arc of the flexible glass 3 in the entire radial direction is smoother.

[0030] In this embodiment, the first clamper 14 includes a first base 18, a first pressure plate 19 that vertically slides with the first base 18, and a first locking member 20 for fixing the first pressure plate 19 and the first base 18. The output end of the first jack 16 is connected to the first base 18. The first pressure plate 19 and the first base 18 are separated to form a clamping space for the flexible glass 3. The degree of clamping can be adjusted by adjusting the position of the first pressure plate 19. The second clamp 15 includes a second base 21, a second pressure plate 22 that vertically slides with the second base 21, and a second locking member 23 for fixing the second pressure plate 22 and the second base 21. The output end of the second jack 17 is connected to the second base 21. The second pressure plate 22 and the second base 21 are separated to form a clamping space for the flexible glass 3. 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 on the outside of the second clamp 15. The base and the second pressure plate 22 are provided with an opening 24 for making way for the first clamp 14 to avoid interference between the first clamp 14 and the second clamp 15.

[0031] In the embodiment of the present invention, a vertical guide rod is fixed on the second base 21, and 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 a nut, and the clamping degree of the second clamp 15 can be adjusted by adjusting the position of the second pressing plate 22. The use of two clamps can improve the force and make it easier for the flexible glass 3 to deform regularly.

[0032] In this embodiment, a hinge seat 25 is fixed on the end surface of the support plate 13 facing the center of the flexible glass 3, and a rotating drum 27 is hingedly connected to the hinge seat 25 through a connecting rod 26. The rotating drum 27 is rotatably mounted at the center of the bottom plate 10, and the rotating drum 27 is connected to 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 outside of the rotating drum 27, the gear ring is meshed with the gear, and the gear is driven to rotate by the motor. By using the rotating drum 27, each support plate 13 can be uniformly slidably adjusted, and the radial distance can be uniformly controlled.

[0033] As a further improvement of the embodiment of the present invention, a support 29 is fixed to the lower side of the slider 12, and the support 29 is connected to a hydraulic cylinder 30, which is installed on the lower side of the bottom plate 10, and a slide groove 31 for the support 29 to cooperate is provided on the bottom plate 10. By separately cooperating the slider 12 with the hydraulic cylinder 30, the position of the slider 12 can be fine-tuned to meet the needs of radial position changes at different positions, thereby ensuring the uniformity of deformation of the flexible glass 3 at various locations in the circumferential direction.

[0034] In this embodiment, a gas cylinder 32 is installed on the lower side of the bottom plate 10, and the gas cylinder 32 is connected to a heating gas connection pipe 33. An air hole 34 is opened on the bottom plate 10, and the gas cylinder 32 is connected to the air hole 34 through an air pipe 35. By using the air hole 34, hot air can be sprayed to the flexible glass 3, which can be 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.

[0035] In this embodiment, the wall microstructure includes a plurality of array columns installed on the surface of the flexible glass 3. Microscopic photolithography is used to etch micrometer-scale array columns on the wall. The width of the array column is w, the height is h, and the spacing is b. The contact angle of the droplet 2 on the wall is adjusted by changing the width w, height h and spacing b of the array column, so that the static contact angle of the droplet 2 on the wall of the flexible glass 3 is in the range of 5~150°.

[0036] An interference experiment method for a droplet 2 impacting a wall surface with a microstructure, using an interference experiment device such as any of the above, a droplet generator 1 is used to emit a droplet 2 to the wall microstructure, the light emitted by an LED lamp 5 illuminates the entire process of the droplet 2 impacting the wall surface with the microstructure from the side, and then the light is emitted into a monochrome high-speed camera 4 to capture the outline of the droplet 2 impacting the wall surface with the microstructure; then, a custom Matlab program is used to calculate the size and impact speed of the droplet 2 in the image; a color high-speed camera 6 is placed vertically, and the white light emitted by a metal halide lamp 7 is reflected to the bottom surface of a flexible glass 3 with a 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 3 with a microstructure, and another part of the light passes through the flexible glass 3 with a microstructure and is incident on the bottom of the droplet 2 and is reflected from the bottom surface of the droplet 2; The two beams of light reflected by the microstructured flexible glass 3 and the bottom surface of the droplet 2 interfere with each other to form interference fringes of different colors, which pass through a semi-transparent and semi-reflective mirror and then enter a color high-speed camera 6. The interference fringes of the air film at the bottom of the lens are obtained by photographing, 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 lens profile. Then, the color of the interference fringes is matched with the thickness of the air film. In the process of processing the real air film at the bottom of the droplet 2, the interference image with the real 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 real thickness of the air film at the bottom of the droplet 2 can be obtained.

[0037] The present invention proposes an experimental device that can simultaneously obtain the macroscopic contour of the millimeter-level droplet 2 and the microscopic morphology of the micron-level air film during the process of the droplet 2 impacting the wall with microstructures, which can realize the experimental measurement of the millimeter-level droplet 2 and the micron-level air film at different time and space scales, obtain the conversion law of the flow state in 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 the spreading and wetting during the impact of the droplet 2. 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 droplet 2 impacting the wall with microstructures, and finally provide theoretical guidance for the application of spray cooling technology in spacecraft thermal control.

[0038] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. 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 inclined toward the direction of the metal halide lamp, 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.

2. The interference experimental device of droplet impacting a microstructured wall according to claim 1, characterized in that: The glass bender includes a base plate and a plurality of guide rails uniformly distributed on the upper surface of the base plate along the circumference of the flexible glass, wherein the guide rails extend along the radial direction of the flexible glass, and a slider is slidably mounted on the guide rails, a support plate is fixed on the upper side of the slider, an adjustable vertical support member is mounted on the support plate, and a clamping member for clamping the flexible glass is connected to the output end of the adjustable vertical support member.

3. The interference experimental device of droplet impacting a microstructured wall according to claim 2, characterized in that: The clamping member includes a first clamp and a second clamp, and the adjustable vertical support member includes a first jack and a second jack, wherein the first jack and the second jack are used for adjustably supporting the first clamp and the second clamp, respectively.

4. The interference experimental device of droplet impacting a microstructured wall according to claim 3, characterized in that: The first clamp includes a first base, a first pressure plate that vertically slides with the first base, and a first locking member for fixing the first pressure plate and the first base. The output end of the first jack is connected to the first base. A clamping space for flexible glass is formed between the first pressure plate and the first base.

5. The interference experimental device of droplet impacting a wall with a microstructure according to claim 4, characterized in that: The second clamp includes a second base, a second pressure plate that vertically slides with the second base, and a second locking member for fixing the second pressure plate and the second base. The output end of the second jack is connected to the second base. The second pressure plate and the second base are separated to form a clamping space for the flexible glass. 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. The base and the second pressure plate are provided with openings for making way for the first clamp.

6. The interference experimental device of droplet impacting a wall with a microstructure according to claim 2, 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.

7. The interference experimental device of droplet impacting a wall with a microstructure according to claim 6, 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.

8. The interference experimental device for droplet impacting a microstructured wall according to any one of claims 2 to 7, 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.

9. 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°.

10. Interference experimental method of droplet impacting a microstructured wall, characterized by: An interference experiment device as described in any one of claims 1 to 9 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, 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 reflected beams of light interfere to form interference fringes of different colors, which pass through a semi-transparent and semi-reflective mirror and then enter a color high-speed camera. The interference fringes of the air film at the bottom of the lens are obtained by photographing, 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 based on the lens profile. Then, the color of the interference fringes is matched with the thickness of the air film. In the process of processing the real air film at the bottom of the droplet, the interference image with the real 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 real thickness of the air film at the bottom of the droplet can be obtained.

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