A method, system and apparatus for gas microflow rate determination based on liquid surface tension

Abstract

This invention relates to the technical field of gas microflow velocity measurement, and proposes a method, system, and apparatus for gas microflow velocity measurement based on liquid surface tension. The method includes the following steps: controlling the injection of liquid B into a container, and then controlling the droplet addition of immiscible liquid A onto the surface of liquid B in the container; a positioning rod connects liquid A and liquid B; a wind-measuring plate floats on liquid A; under gas flow, the wind-measuring plate moves, causing liquid A to deform on liquid B; images are acquired to obtain the morphological parameters of liquid A under wind blowing; the ellipse eccentricity is calculated based on the morphological parameters of liquid A; a gas velocity calculation formula is constructed; the flow velocity of the measured gas is obtained and output based on the ellipse eccentricity and the gas velocity calculation formula; this invention requires only two immiscible liquids, a positioning rod, and a wind-measuring plate, reducing equipment costs; and achieves optical non-contact measurement by acquiring the morphological parameters of liquid A through image acquisition, exhibiting higher sensitivity and stability.

Description

Technical Field

[0001] This invention relates to the technical field of gas microflow velocity measurement, and in particular to a method, system, and apparatus for measuring gas microflow velocity based on liquid surface tension. Background Technology

[0002] The accurate measurement of gas microvelocities has significant application value in fields such as meteorological monitoring, industrial ventilation, environmental science, and biomedical engineering. Traditional gas velocity measurement methods are mainly classified into mechanical, thermal, and differential pressure methods.

[0003] Mechanical anemometers (such as cup anemometers and propeller anemometers) are simple in structure and highly reliable, but their rotating parts have inertia, resulting in high starting wind speeds. They are typically difficult to accurately measure micro-velocities below 0.2 m / s, and the rotating parts are prone to wear and tear after prolonged use, leading to decreased accuracy. Thermal anemometers (such as hot-wire anemometers) are based on the principle of heat dissipation and can measure low wind speeds, but their probes are sensitive to changes in ambient temperature, susceptible to dust contamination, and lack long-term stability, requiring frequent calibration. Their lifespan is limited in high-humidity or corrosive gas environments. Differential pressure micromanometers (such as pitot tubes) are based on Bernoulli's principle, calculating flow velocity by detecting the difference between dynamic and static pressure. Under micro-velocity conditions, the differential pressure signal is extremely weak, requiring extremely high sensor sensitivity and anti-interference capabilities, making it difficult to guarantee measurement accuracy. Therefore, existing microvelocity measurement technologies often struggle to balance high sensitivity, low cost, and stability in complex environments. Summary of the Invention

[0004] To address the aforementioned shortcomings, the present invention aims to provide a method, system, and apparatus for measuring gas microvelocities based on liquid surface tension, thereby solving the problem that existing technologies struggle to balance high sensitivity, low cost, and stability.

[0005] To achieve this objective, the present invention adopts the following technical solution: A method for measuring gas microvelocities based on liquid surface tension includes the following steps: S1, control the injection of liquid B into the container, and then control the dripping of immiscible liquid A onto the surface of liquid B in the container. A positioning rod connects liquid A and liquid B. S2, Liquid A has a wind measuring plate floating on it. Under the gas flow, the wind measuring plate moves, which causes liquid A to deform on liquid B. The image is collected to obtain the morphological parameters of liquid A under the wind. S3, calculate the eccentricity of the ellipse based on the morphological parameters of liquid A; S4, Construct the formula for calculating gas flow rate; S5 calculates and outputs the velocity of the measured airflow based on the ellipse eccentricity and the gas velocity calculation formula.

[0006] Preferably, in step S3: Ellipse eccentricity ,in Let b be the length of the major semi-axis of liquid A, and let b be the length of the minor semi-axis of liquid A.

[0007] Preferably, in step S4, the formula for calculating the gas flow rate is: , where γ represents the surface tension of liquid A, H represents the thickness of liquid A, ρ is the gas density, and S′ is the equivalent wind-receiving area; = , where K(e) is the elliptic integral of the first kind and E(e) is the elliptic integral of the second kind.

[0008] Preferably, step S2 specifically includes: A clear image of liquid A is obtained by capturing top and side views of liquid A using a camera and performing edge detection on the image under test. Based on the clear image, obtain the contour information of liquid A, and thus obtain the morphological parameters of liquid A: the length of the minor axis of liquid A. , length b of the major semi-axis of liquid A, and thickness H of liquid A.

[0009] This invention proposes a system for measuring gas microflow velocity based on liquid surface tension, characterized in that it comprises: The liquid control module is used to control the injection of liquid B into the container, and then control the addition of immiscible liquid A to the surface of liquid B in the container. The image acquisition module is used to acquire images and obtain the morphological parameters of liquid A under wind blowing. The ellipse eccentricity calculation module is used to calculate the ellipse eccentricity of liquid A based on its morphological parameters. The flow velocity formula construction module is used to construct flow velocity calculation formulas; The calculation output module is used to calculate and output the flow velocity of the measured airflow.

[0010] This invention proposes a device for measuring gas microflow velocity based on liquid surface tension, characterized in that it includes a container 1, a droplet injection mechanism 2, liquid A, liquid B, a positioning rod 3, a wind measuring plate 4, a camera 5, and a processor 6, wherein the processor 6 is used to execute the gas microflow velocity measurement method. The droplet injection mechanism 2 is used to inject liquid A and liquid B; The container 1 is used to contain liquid A and liquid B, the positioning rod 3 connects liquid A and liquid B, the wind measuring plate is cylindrical, and the wind measuring plate is disposed on the surface of liquid A; The camera 5 is provided in two sets, which are respectively set above and to the side of the container 1, for filming liquid A.

[0011] Preferably, liquid B is water, and liquid A is silicone oil or an alkane liquid.

[0012] Preferably, the wind measuring plate is a telescopic rod, which can change its length by extending and retracting, thereby changing the equivalent wind-receiving area.

[0013] Preferably, the device further includes a light source assembly 7, which is used to irradiate the liquid A.

[0014] One of the above technical solutions has the following advantages or beneficial effects: This invention utilizes a liquid A floating on the surface of an immiscible liquid B, combined with a wind-measuring plate structure, to convert minute airflow driving forces into macroscopic deformation (elliptical shape change) of liquid A. Because the surface tension of liquids is extremely sensitive to force, even extremely low-velocity airflow can cause observable deformation of the droplets, exhibiting high sensitivity. This solves the problems of traditional mechanical anemometers, such as high start-up wind speed, low sensitivity, and difficulty in measuring microvelocities. This method requires only two immiscible liquids, a container, a positioning rod, and a wind-measuring plate, eliminating the need for precision machining or expensive sensor chips, significantly reducing equipment manufacturing costs and maintenance difficulty. By acquiring images to obtain the morphological parameters of liquid A, optical non-contact measurement is achieved, avoiding direct insertion of the sensor probe into the airflow and preventing flow field disturbances. This effectively avoids the defects of easy failure in humid and corrosive environments. The measurement process is intuitive and visual, facilitating real-time monitoring and recording, and exhibiting higher stability. Attached Figure Description

[0015] Figure 1 This is a flowchart of one embodiment of the method proposed in this invention; Figure 2 This is a schematic diagram of the structure of one embodiment of the system proposed in this invention; Figure 3 This is an overall schematic diagram of one embodiment of the device proposed in this invention; Figure 4 This is a schematic diagram of the deformation of liquid A under wind blowing in one embodiment of the device proposed in this invention.

[0016] The components include: 1. Container; 2. Droplet injection mechanism; 3. Liquid A; 4. Liquid B; 5. Positioning rod; 6. Anemometer plate; 7. Camera; 8. Processor; 9. Light source assembly. Detailed Implementation

[0017] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are used to explain the present invention only based on the measurement of gas microflow rates using liquid surface tension, and should not be construed as limiting the present invention.

[0018] In the description of this invention, it should be understood that the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, features defined with "first" and "second" may explicitly or implicitly include one or more of these features. The gas microflow velocity measurement based on liquid surface tension distinguishes descriptive features without any order or emphasis.

[0019] In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0020] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] The following is combined Figure 1 A method for measuring gas microflow velocity based on liquid surface tension according to an embodiment of the present invention includes the following steps: S1, control the injection of liquid B into the container, and then control the dripping of immiscible liquid A onto the surface of liquid B in the container. A positioning rod connects liquid A and liquid B. S2, Liquid A has a wind measuring plate floating on it. Under the gas flow, the wind measuring plate moves, which causes liquid A to deform on liquid B. The image is collected to obtain the morphological parameters of liquid A under the wind. S3, calculate the eccentricity of the ellipse based on the morphological parameters of liquid A; S4, Construct the formula for calculating gas flow rate; S5 calculates and outputs the velocity of the measured airflow based on the ellipse eccentricity and the gas velocity calculation formula.

[0022] This method is based on the high sensitivity of liquid surface tension to weak external forces. It converts the kinetic energy of gas flow into the shape change of floating droplets, extracts morphological feature parameters using image processing technology, obtains the elliptical eccentricity, and finally calculates the gas microvelocity based on a pre-constructed mathematical model. Its core lies in utilizing the stable interface formed by two immiscible liquid phases and the force amplification and transmission effect of the anemometer on the airflow to achieve the physical quantity conversion from airflow velocity to droplet geometry and then to numerical output. The specific working principle is as follows: Liquid B, as the lower liquid phase, is injected into the container to provide a stable substrate; Liquid A is dropped onto the surface of Liquid B. Since the two are immiscible and have different densities (generally, the density of Liquid A is less than that of Liquid B), the interface between the two liquids has a stable surface tension coefficient. This tension allows Liquid A to maintain a minimum surface energy state when no external force is applied, i.e., a circular or near-circular projection shape floating on the surface of Liquid B; A wind-measuring plate floats above Liquid A. When the measured airflow passes over the wind-measuring plate, the airflow exerts a horizontal thrust on the wind-measuring plate. This force is transmitted to Liquid A through the wind-measuring plate structure. Due to the surface tension at the interface between Liquid A and Liquid B, Liquid A undergoes elastic deformation when subjected to a horizontal external force, and its horizontal projection changes from a circle to an ellipse; The liquid surface image of Liquid A is captured from above by a camera or image sensor, and the geometric parameters of the droplet projection, i.e., the lengths of the major and minor semi-axes, are processed and obtained. The eccentricity e of the ellipse is calculated, and the eccentricity e is substituted into a pre-constructed flow velocity calculation formula to obtain the real-time flow velocity value of the measured airflow, which is then output through a display module or data interface; By utilizing the floating of liquid A on the surface of immiscible liquid B, combined with a wind-measuring plate structure, the minute airflow driving force is converted into macroscopic deformation (elliptical shape change) of liquid A. Because the surface tension of liquids is extremely sensitive to force, even extremely low-velocity airflow can cause observable deformation of the droplets, exhibiting high sensitivity. This solves the problems of traditional mechanical anemometers, such as high start-up wind speed, low sensitivity, and difficulty in measuring microvelocities. This method requires only two immiscible liquids, a container, a positioning rod, and a wind-measuring plate, eliminating the need for precision machining or expensive sensor chips, significantly reducing equipment manufacturing costs and maintenance difficulty. By acquiring images to obtain the morphological parameters of liquid A, optical non-contact measurement is achieved, avoiding the flow field disturbance caused by directly inserting the sensor probe into the airflow. This effectively avoids the defects of easy failure in humid and corrosive environments. The measurement process is intuitive and visual, facilitating real-time monitoring and recording, and exhibiting higher stability.

[0023] Furthermore, in step S3: the eccentricity of the ellipse ,in Let b be the length of the major semi-axis of liquid A, and let b be the length of the minor semi-axis of liquid A.

[0024] Under windless conditions, liquid A is circular under the action of surface tension, with an eccentricity e = 0. When the measured air flow acts on the wind measurement plate, liquid A undergoes deformation. The liquid surface image of liquid A is collected from above by a camera or an image sensor, processed, and the geometric parameters of the liquid droplet projection, that is, the lengths of the long semi-axis and the short semi-axis, are obtained, and the elliptical eccentricity e is calculated. The value range of the eccentricity e is 0 < e < 1, and the value of the eccentricity e increases with the increase of the liquid droplet deformation degree, directly reflecting the magnitude of the horizontal external force received by liquid A.

[0025] Furthermore, in step S4, the gas flow velocity calculation formula is: , where γ represents the surface tension of liquid A, H represents the thickness of liquid A, ρ is the gas density, and S′ is the equivalent wind-receiving area; = , where K(e) is the first kind of elliptic integral and E(e) is the second kind of elliptic integral.

[0026] Specifically, when the gas flows at a flow velocity v, the thrust exerted by the air flow on the wind measurement plate is: , and this thrust is transmitted to liquid A through the wind measurement plate, causing liquid A to deform on the surface of liquid B. During the deformation process of liquid A, the surface tension generates a restoring force, which is related to the deformation degree. Under steady-state conditions, the air flow thrust and the surface tension restoring force reach equilibrium. Liquid A changes from a circular shape to an elliptical shape under the action of the horizontal external force, and its surface energy increases. The surface tension restoring force comes from the energy change corresponding to the increase in the interface area of liquid A. For a thin liquid droplet (with a small thickness HH) floating on an immiscible liquid, the relationship between its deformation and surface tension can be derived from the liquid droplet mechanical model. The deformation parameter factor actually represents the interface perimeter change rate corresponding to the change in the unit long axis, reflecting the geometric sensitivity of the liquid droplet deformation. The product represents the surface tension energy per unit width of liquid A and determines the elastic stiffness of the system. The larger it is, the stronger the ability of the liquid droplet to resist deformation, and the smaller the eccentricity e at the same flow velocity. represents the driving force coefficient of the air flow on the wind measurement plate. The larger it is, the greater the thrust at the same flow velocity, and the more significant the liquid droplet deformation.

[0027] Using the exact solution of the elliptic integral instead of the linear approximation makes this formula maintain high precision in the full range from low wind speeds (e≈0) to high wind speeds (e→1). This formula accurately describes the nonlinear behavior through the elliptic integral, ensuring the measurement accuracy in the full range and can change by selecting different liquids (such as water, ethanol, silicone oil, etc.) and adjusting the liquid droplet volume to optimize the sensitivity, and can change To match the needs of different wind speeds, since the formula is based on rigorous mechanical and geometric derivation, in determining the liquid parameters ( ) and wind measurement plate parameters ( After that, the theoretical curve can be determined, which greatly reduces the amount of experimental work.

[0028] Furthermore, step S2 specifically includes: A clear image of liquid A is obtained by capturing top and side views of liquid A using a camera and performing edge detection on the image under test. Based on the clear image, obtain the contour information of liquid A, and thus obtain the morphological parameters of liquid A: the length of the minor axis of liquid A. , length b of the major semi-axis of liquid A, and thickness H of liquid A.

[0029] Specifically, a camera simultaneously captures top and side views of liquid A. Image processing techniques are used to obtain the complete three-dimensional morphological parameters of the droplet, including the minor axis length 'a', the major axis length 'b', and the thickness 'H', providing data for subsequent gas velocity calculations. Capturing liquid A from both top and side views avoids interference from other structures in the imaging. The camera has no physical contact with the object being measured, thus avoiding disturbance to the flow field and ensuring that the measurement results reflect the true airflow state. The overall contour of liquid A under the influence of the flow field is clearly obtained. Edge detection of the acquired images effectively suppresses interference from uneven illumination, highlighting the boundary features of liquid A and yielding a high-contrast, high-definition contour image of liquid A. This significantly improves the accuracy and stability of morphological parameter extraction. By treating liquid A as an equivalent ellipsoidal model, only the minor axis length needs to be obtained. The length of the semi-major axis b can characterize the deformation state of liquid A after being scoured by the fluid. It has few characteristic parameters, low computational load, and is easy to process in real time, which is conducive to realizing rapid calculation and online measurement of airflow velocity. The entire acquisition and detection process is realized only through optical imaging, without contacting or interfering with the shape of liquid A and the measured flow field, ensuring the in-situ nature and authenticity of the measurement process.

[0030] like Figure 2 This invention proposes a system for measuring gas microflow velocity based on liquid surface tension, comprising: The liquid control module is used to control the injection of liquid B into the container, and then control the addition of immiscible liquid A to the surface of liquid B in the container. The image acquisition module is used to acquire images and obtain the morphological parameters of liquid A under wind blowing. The ellipse eccentricity calculation module is used to calculate the ellipse eccentricity of liquid A based on its morphological parameters. The flow velocity formula construction module is used to construct flow velocity calculation formulas; The calculation output module is used to calculate and output the flow velocity of the measured airflow.

[0031] like Figure 3 and 4 This invention proposes a device for measuring gas microflow velocity based on liquid surface tension, comprising a container 1, a droplet injection mechanism 2, liquid A, liquid B, a positioning rod 3, a wind measuring plate 4, a camera 5, and a processor 6, wherein the processor 6 is used to execute the gas microflow velocity measurement method. The droplet injection mechanism 2 is used to inject liquid A and liquid B; The container 1 is used to contain liquid A and liquid B, the positioning rod 3 connects liquid A and liquid B, the wind measuring plate is cylindrical, and the wind measuring plate is disposed on the surface of liquid A; The camera 5 is provided in two sets, which are respectively set above and to the side of the container 1, for filming liquid A.

[0032] Specifically, this device utilizes the sensitive response of liquid surface tension to weak airflow to achieve optical measurement of flow velocity by constructing a stable two-phase liquid system. During operation, liquid B is injected into container 1 as a substrate via droplet injection mechanism 2, and liquid A is then dropped onto the surface of liquid B. The two are connected by positioning rod 3 to ensure that liquid A remains stable under pressure and does not drift. A cylindrical wind-measuring plate floats or is fixed to the surface of liquid A. When the measured airflow passes over it, the wind-measuring plate experiences airflow thrust, which is transmitted to liquid A, causing it to deform on the surface of liquid B. The projection is stretched from a circle to an ellipse, and the thickness of the droplet changes accordingly. Two sets of cameras 5, located directly above and to the side of container 1, simultaneously acquire top and side views of liquid A. The processor 6 performs edge detection, contour fitting, and parameter extraction on the acquired images to obtain morphological parameters such as the major and minor axes and thickness of the ellipse of liquid A. Then, the eccentricity of the ellipse is calculated and substituted into the pre-constructed flow velocity calculation formula to finally obtain the micro-flow velocity value of the gas being measured. The whole process realizes the complete physical quantity conversion from airflow thrust to droplet deformation, and then to geometric parameter extraction and numerical output. The anemometer plate is cylindrical, which can generate a stable and repeatable thrust response regardless of the change in airflow direction. Even under wind, the cross-sectional area does not change, and the equivalent wind-receiving area S′ remains unchanged, simplifying the direction calibration process. By adopting a structure in which the cylindrical anemometer plate cooperates with the positioning rod 3, the efficient transmission of airflow thrust to liquid A is ensured, and the drift and rotation of droplets during deformation are effectively suppressed, significantly improving the stability and repeatability of the measurement.

[0033] Furthermore, liquid B is water, and liquid A is silicone oil or an alkane liquid.

[0034] Specifically, silicone oil and alkane liquids possess excellent chemical inertness, exhibiting no chemical reaction, hydrolysis, or oxidation with water. During use, the two liquid phases maintain stable interfacial characteristics and physical parameters, preventing changes in surface tension or interfacial contamination due to chemical reactions. Water exhibits high interfacial tension with silicone oil or alkane liquids (water-silicone oil interfacial tension approximately 30-50 mN / m, water-alkane interfacial tension approximately 40-50 mN / m). This high interfacial tension provides stronger deformation recovery force, enabling liquid A to quickly recover to its initial state after being subjected to airflow thrust. This improves the system's response speed and dynamic tracking capability, while also enhancing the mechanical coupling between droplet deformation and airflow thrust, effectively improving measurement sensitivity and stability.

[0035] Furthermore, the wind measuring plate is a telescopic rod, which can change its length by extending or retracting, thereby changing the equivalent wind-receiving area.

[0036] Specifically, this technical solution designs the wind measuring plate as a telescopic rod structure. The equivalent wind-receiving area S′=d×L is adjusted by extending and retracting the rod to change its length, where d is the diameter of the telescopic rod and L is the length of the telescopic rod. The telescopic rod structure is simple and reliable, and can adopt a multi-section sleeve type or threaded telescopic design. Manual adjustment requires no additional power, and the telescopic adjustment operation is simple and quick. The equivalent wind-receiving area S′ is the product of the diameter of the telescopic rod and the length of the telescopic rod. Changing the length of the telescopic rod by extending or retracting changes the equivalent wind-receiving area S′.

[0037] Furthermore, the device also includes a light source assembly 7, which is used to irradiate the liquid A.

[0038] Specifically, the light source component 7 provides uniform and sufficient illumination for liquid A. Under the auxiliary illumination of the light source, the difference in brightness between liquid A and liquid B is amplified, and the outline of liquid A is clearer and more prominent. This compensates for the problem of insufficient ambient light or uneven lighting, enabling the camera 5 to obtain liquid A images with suitable brightness in various measurement environments, and avoiding blurry images and information loss due to excessive light.

[0039] Other components and operations of the method, system, and apparatus for measuring gas microflow velocity based on liquid surface tension according to embodiments of the present invention are known to those skilled in the art and will not be described in detail here.

[0040] Furthermore, the functional units in the various embodiments of the present invention can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0041] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequence of executable instructions that implement logical functions based on the determination of gas microflow rates based on liquid surface tension, and can be embodied in any computer-readable medium for use by, or in conjunction with, instruction execution systems, apparatuses, or devices (such as computer-based systems, systems including processing modules, or other systems that can fetch and execute instructions from and from such instruction execution systems, apparatuses, or devices).

[0042] In the description of this specification, references to terms such as "embodiment," "example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0043] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for measuring gas microflow velocity based on liquid surface tension, characterized in that, Includes the following steps: S1, control the injection of liquid B into the container, and then control the dripping of immiscible liquid A onto the surface of liquid B in the container. A positioning rod connects liquid A and liquid B. S2, Liquid A has a wind measuring plate floating on it. Under the gas flow, the wind measuring plate moves, which causes liquid A to deform on liquid B. The image is collected to obtain the morphological parameters of liquid A under the wind. S3, calculate the eccentricity of the ellipse based on the morphological parameters of liquid A; S4, Construct the formula for calculating gas flow rate; S5 calculates and outputs the velocity of the measured airflow based on the ellipse eccentricity and the gas velocity calculation formula.

2. The method for measuring gas microvelocities based on liquid surface tension according to claim 1, characterized in that, In step S3: Ellipse eccentricity ,in Let b be the length of the major semi-axis of liquid A, and let b be the length of the minor semi-axis of liquid A.

3. The method for measuring gas microvelocities based on liquid surface tension according to claim 1, characterized in that, In step S4, the formula for calculating the gas flow rate is: , where γ represents the surface tension of liquid A, H represents the thickness of liquid A, ρ is the gas density, and S′ is the equivalent wind-receiving area; = , where K(e) is the elliptic integral of the first kind and E(e) is the elliptic integral of the second kind.

4. The method for measuring gas microvelocities based on liquid surface tension according to claim 1, characterized in that, Step S2 specifically includes: A clear image of liquid A is obtained by capturing top and side views of liquid A using a camera and performing edge detection on the image under test. Based on the clear image, obtain the contour information of liquid A, and thus obtain the morphological parameters of liquid A: the length of the minor axis of liquid A. , length b of the major semi-axis of liquid A, and thickness H of liquid A.

5. A system for measuring gas microflow velocity based on liquid surface tension, characterized in that, include: The liquid control module is used to control the injection of liquid B into the container, and then control the addition of immiscible liquid A to the surface of liquid B in the container. The image acquisition module is used to acquire images and obtain the morphological parameters of liquid A under wind blowing. The ellipse eccentricity calculation module is used to calculate the ellipse eccentricity of liquid A based on its morphological parameters. The flow velocity formula construction module is used to construct flow velocity calculation formulas; The calculation output module is used to calculate and output the flow velocity of the measured airflow.

6. A device for measuring gas microvelocities based on liquid surface tension, characterized in that, It includes a container 1, a droplet injection mechanism 2, liquid A, liquid B, a positioning rod 3, a wind measuring plate 4, a camera 5, and a processor 6, wherein the processor 6 is used to execute the gas microflow velocity measurement method as described in any one of claims 1-4; The droplet injection mechanism 2 is used to inject liquid A and liquid B; The container 1 is used to contain liquid A and liquid B, the positioning rod 3 connects liquid A and liquid B, the wind measuring plate is cylindrical, and the wind measuring plate is disposed on the surface of liquid A; The camera 5 is provided in two sets, which are respectively set above and to the side of the container 1, for filming liquid A.

7. A device for measuring gas microflow velocity based on liquid surface tension according to claim 6, characterized in that, Liquid B is water, and liquid A is silicone oil or an alkane liquid.

8. A device for measuring gas microvelocities based on liquid surface tension according to claim 6, characterized in that, The wind measuring plate is a telescopic rod, which can change its length by extending and retracting, thereby changing the equivalent wind-receiving area.

9. A device for measuring gas microvelocities based on liquid surface tension according to claim 6, characterized in that, The device also includes a light source assembly 7, which is used to irradiate the liquid A.

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