A magnetic liquid interfacial tension coefficient measuring device and method

Abstract

The application provides a magnetic liquid interfacial tension coefficient measuring device and method, relates to the field of magnetic liquid physical property characterization, and comprises the following steps: placing a container containing a magnetic liquid and a liquid insoluble with the magnetic liquid at the center of a uniform magnetic field, taking a picture of the situation in the container by a camera and transmitting the picture to a computer for analysis and processing, recording the magnetic field strength when the Rosensweig instability phenomenon occurs at the interface between the magnetic liquid and the insoluble liquid, and calculating the interfacial tension coefficient of the magnetic liquid according to different magnetic field strength ranges by using different methods. The application divides the influence of the magnetic field on the interfacial tension coefficient into a weak magnetic field before the Rosensweig instability occurs and a strong magnetic field greater than the threshold value, so that the measurement of the interfacial tension coefficient under two magnetic field conditions can be realized on one device. Moreover, the measurement result of the application is not affected by the interface deformation, and the measurement result is more accurate.

Description

Technical Field

[0001] This invention relates to the field of characterization technology of the physical properties of magnetic liquids, and in particular to a device and method for measuring the interfacial tension coefficient of magnetic liquids. Background Technology

[0002] Magnetic fluids are colloidal systems formed by nanoscale ferromagnetic particles coated with surfactants suspended in a liquid medium, and are widely used in engineering fields such as sealing and lubrication. In practical applications, when another immiscible liquid is in contact with the magnetic fluid, the interfacial tension between them is a key factor determining the flow characteristics of the magnetic fluid and the shape of the interface between the two liquids. Therefore, accurately measuring the interfacial tension coefficient between a specific magnetic fluid and another immiscible liquid is crucial for accurately establishing a magnetic fluid flow model.

[0003] In existing technologies, methods for obtaining interfacial tension coefficients include tensiometer-based methods, such as the Du Nouy ring and Wilhelmy plate methods, or indirect methods by observing the shape of suspended droplets or measuring the rise of the liquid level in a capillary. However, when using these methods to measure the interfacial tension coefficient of magnetic fluids, the interface is curved, causing a significant change in the direction of the magnetic field lines relative to the applied magnetic field. In this case, the influence of interfacial tension must be separated from the magnetic field effect, resulting in ambiguity in the results when using traditional tensiometer methods. On the other hand, when studying interfacial tension under the influence of a magnetic field, the interfacial deformation caused by the magnetic field can affect the measurement results of traditional methods. Summary of the Invention

[0004] To address the technical problems existing in the prior art, embodiments of the present invention provide a device and method for measuring the interfacial tension coefficient of magnetic liquids. The technical solution is as follows:

[0005] A magnetic liquid interfacial tension coefficient measuring device includes a horizontal base, a container placed on the base, the container containing a magnetic liquid to be measured and a first liquid immiscible with the magnetic liquid to be measured, a light source and a first camera respectively placed on the base and on both sides of the container, a second camera placed directly above the container, the first camera and the second camera being electrically connected to a computer, a Helmholtz coil placed on one side of the container to position the container at the center of a uniform magnetic field, and the Helmholtz coil being electrically connected to a second power source.

[0006] A method for measuring the interfacial tension coefficient of a magnetic liquid, comprising the aforementioned measuring device for the interfacial tension coefficient of a magnetic liquid, the method comprising:

[0007] S1. Gradually increase the magnetic field until Rosensweig instability occurs at the interface between the magnetic liquid and the first liquid, and record the magnetic field strength at this point. ;

[0008] S2. Define the range of magnetic field strength;

[0009] S3. Calculate the interfacial tension coefficient of magnetic fluids using different methods depending on the range of magnetic field strength.

[0010] Optionally,

[0011] The magnetic field is gradually increased as described in S1 until Rosensweig instability occurs at the interface between the magnetic liquid and the first liquid. The magnetic field strength at this point is recorded. include:

[0012] By gradually increasing the current of the second power source, the magnetic field generated by the Helmholtz coil is gradually strengthened. The interface deformation between the magnetic liquid and the first liquid in the container is observed by the computer through the images captured by the first camera and the second camera.

[0013] Optionally,

[0014] The segmentation of the magnetic field strength range in S2 includes: setting the magnetic field strength as... When the magnetic field strength is less than or equal to the critical magnetic field strength, it is considered critical. At this time, the magnetic field is set as a weak magnetic field. When the magnetic field strength is greater than... At this time, the magnetic field is set to a strong magnetic field;

[0015] The step S3, which involves calculating the interfacial tension coefficient of the magnetic fluid using different methods for different magnetic field strength ranges, includes:

[0016] When the magnetic field is weak, Method 1 is used to calculate the interfacial tension coefficient of the magnetic liquid; when the magnetic field is strong, Method 2 is used to calculate the interfacial tension coefficient of the magnetic liquid.

[0017] Optionally,

[0018] The first method includes:

[0019] S101. Calculate the magnetic induction intensity in the magnetic fluid and obtain the first parameter through iterative calculation;

[0020] S102. Calculate the second parameter and the magnetization intensity of the magnetic fluid based on the first parameter;

[0021] S103. The magnetic field strength inside the magnetic fluid is calculated based on the critical magnetic field strength and the magnetization of the magnetic fluid.

[0022] S104. The third parameter is calculated based on the second parameter, the magnetic induction intensity in the magnetic liquid, and the magnetic field intensity in the magnetic liquid;

[0023] S105. The interfacial tension coefficient of the magnetic liquid under a weak magnetic field is calculated based on the third parameter and the magnetization intensity of the magnetic liquid.

[0024] Optionally,

[0025] The second method includes:

[0026] S201. Empty the liquid in the container, put a first liquid that is immiscible with the magnetic liquid to be tested in the container, and drip the droplet of the magnetic liquid to be tested into the first liquid.

[0027] S202, Increase the first power supply current to make the magnetic field strength generated by the Helmholtz coil greater than... Record the magnetic field strength at this time as ;

[0028] S203, The first camera and the second camera capture images when the magnetic field strength is... At that time, the interface deformation between the magnetic liquid and the first liquid in the container is recorded and transmitted to the computer. The computer processes the data to determine the magnetic field strength when it is... At that time, the longitudinal half-length b and the transverse half-length of the magnetic liquid droplet in the first liquid ratio And the contact angle size of the shape of the magnetic liquid droplet in the first liquid. ;

[0029] S204, Input the known density, viscosity, and permeability of the magnetic liquid, the known density, viscosity, and permeability of the first liquid, and the contact angle obtained by the computer into the computer. and magnetic field strength The computer calculates using a two-phase flow calculation method.

[0030] By inputting multiple different preset interfacial tension coefficients, the ratio of the longitudinal half-length to the transverse half-length of the magnetic liquid droplet shape in the first liquid corresponding to each preset interfacial tension coefficient is obtained. ;

[0031] Thus, the ratio of the longitudinal half-length to the transverse half-length of the magnetic liquid droplet's shape in the first liquid is obtained. The relationship curve between the interfacial tension coefficient and the interfacial tension coefficient is shown in curve l.

[0032] S205. On curve l, using interpolation, we obtain the result when the magnetic field strength is... The longitudinal half-length b and the transverse half-length of the magnetic liquid droplet in the first liquid are... The ratio is When, the interfacial tension coefficient of the corresponding magnetic fluid.

[0033] Optionally,

[0034] The calculation of the magnetic induction intensity within the magnetic fluid in step S101, and the iterative calculation to obtain the first parameter, includes:

[0035] The formula for calculating the magnetic induction intensity in the magnetic fluid is formula (1):

[0036] (1)

[0037] in, The magnetic flux density within the magnetic fluid. The known permeability of free space;

[0038] The iterative formula for obtaining the first parameter through iterative calculation is formula (2):

[0039] (2)

[0040] in,

[0041]

[0042]

[0043] in, The first parameter is the iteration parameter. Boltzmann's constant, Given the temperature, Given the saturation magnetization of a known magnetic fluid, Let be the magnetic moment of a single magnetic particle in a known magnetic fluid.

[0044] Optionally,

[0045] The step S102, which calculates the second parameter and the magnetization of the magnetic fluid based on the first parameter, includes:

[0046] The formula for calculating the second parameter is formula (3):

[0047] (3)

[0048] in, The second parameter;

[0049] The formula for calculating the magnetization of a magnetic fluid is formula (4):

[0050] (4)

[0051] in, The magnetization intensity of the magnetic fluid;

[0052] The calculation of the magnetic field strength within the magnetic fluid based on the critical magnetic field strength and the magnetization of the magnetic fluid in step S103 includes:

[0053] The formula for calculating the magnetic field strength in a magnetic fluid is formula (5):

[0054] (5)

[0055] in, The magnetic field strength within the magnetic fluid;

[0056] The step of S104, which calculates the third parameter based on the second parameter, the magnetic induction intensity in the magnetic fluid, and the magnetic field intensity in the magnetic fluid, includes:

[0057] The formula for calculating the third parameter is formula (6):

[0058] (6)

[0059] in, This is the third parameter.

[0060] Optionally,

[0061] The interfacial tension coefficient of the magnetic liquid calculated based on the third parameter and the magnetization of the magnetic liquid in S105 when the magnetic field is weak includes:

[0062] The formula for calculating the interfacial tension coefficient of a magnetic fluid in a weak magnetic field is formula (7).

[0063] (7)

[0064] in, is the interfacial tension coefficient of the magnetic fluid under a weak magnetic field. It is the acceleration due to gravity. and The densities of the magnetic liquid and the first liquid are known quantities.

[0065] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0066] This method divides the effect of magnetic field on interfacial tension coefficient into a weak magnetic field before Rosensweig instability and a strong magnetic field above the threshold, enabling the measurement of interfacial tension coefficient under both magnetic field conditions on a single device. Utilizing experimental measurements of the shape of a magnetic liquid droplet in a solution incompatible with the magnetic liquid, supplemented by numerical calculations of the magnetic liquid droplet interface based on this shape, the interfacial tension coefficient corresponding to a given magnetic field is ultimately obtained. Furthermore, this invention calculates the interfacial tension coefficient, and compared to traditional tensiometer measurement methods, the results are unaffected by interfacial deformation, resulting in more accurate results. Attached Figure Description

[0067] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0068] Figure 1 A schematic diagram of the structure of a magnetic liquid interfacial tension coefficient measuring device provided by the present invention;

[0069] Figure 2 This is a schematic diagram of the Rosensweig interface instability phenomenon captured by the camera of this invention.

[0070] Figure 3 This describes the shape of the magnetic liquid droplet in the first liquid in this invention.

[0071] Figure label:

[0072] 1. Container; 21. Computer; 22. Base; 23. First camera; 24. Second camera; 25. Light source; 26. Level; 27. Helmholtz coil; 28. First power source; 29. ​​Second power source. Detailed Implementation

[0073] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0074] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms “first,” “second,” and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an,” “a,” or “the,” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising,” “including,” or “including,” and similar terms mean that the element or object preceding the word encompasses the element or object listed following the word and its equivalents, without excluding other elements or objects. The terms “connected,” “linked,” or “connected,” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect.

[0075] It should be noted that the terms "up", "down", "left", "right", "front", and "back" used in this invention are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0076] like Figures 1-3 As shown, this embodiment provides a device and method for measuring the interfacial tension coefficient of magnetic liquids.

[0077] like Figure 1 As shown, this embodiment provides a magnetic liquid interfacial tension coefficient measuring device. A horizontally placed base 22 is leveled using a level 26. A container 1 is placed on the surface of the base 22 via a support. The container contains the magnetic liquid to be measured and a first liquid that is immiscible with the magnetic liquid. A light source 25 and a first camera 23 are respectively installed on the base 22 on both sides of the container 1, with the light source 25, first camera 23, and container 1 at the same height. A second camera 24 is positioned directly above the container 1 and is mounted on the base 22 via a support. The first camera 23 and the second camera 24 are electrically connected to a computer 21. A Helmholtz coil 27 is installed on the base 22, located on one side of the container 1, placing the container 1 at the center of a uniform magnetic field. The Helmholtz coil 27 is electrically connected to a second power supply 29, and the light source 25 is electrically connected to a first power supply 28. The first camera 23 and the second camera 24 are used to photograph the interfacial deformation between the magnetic liquid and the immiscible liquid in the container 1 in the horizontal and vertical directions, respectively. The two cameras are required to be able to resolve interfacial deformation at the micrometer level. The light source 25 is used to project a light beam onto the container 1 to ensure that the first camera 23 and the second camera 24 can clearly capture the interface between the magnetic liquid and the other phase liquid.

[0078] Computer 21 is used to control the first camera 23 and the second camera 24 to take pictures and save the pictures.

[0079] The Helmholtz coil 27 is used to apply a uniform vertical magnetic field to the space containing container 1. The strength of the magnetic field can be changed by adjusting the current input to the Helmholtz coil 27 via the second power supply 29. It is required that the magnetic field strength generated by the Helmholtz coil 27 can cover the saturation magnetic field strength of the magnetic liquid.

[0080] like Figures 1-3 As shown, this embodiment provides a method for measuring the interfacial tension coefficient of a magnetic liquid.

[0081] The method includes:

[0082] S1. Gradually increase the current of the second power supply 29 to gradually strengthen the magnetic field generated by the Helmholtz coil 27. Observe the interface deformation between the magnetic liquid and the first liquid in container 1 as captured by the first camera 23 and the second camera 24 through the computer 21, until the interface between the magnetic liquid and the first liquid exhibits Rosensweig instability. Record the magnetic field strength at this point. ;

[0083] S2. Divide the magnetic field strength range; set the magnetic field strength as... When the magnetic field strength is less than or equal to the critical magnetic field strength, it is considered critical. At this time, the magnetic field is set as a weak magnetic field. When the magnetic field strength is greater than... At this time, the magnetic field is set to a strong magnetic field;

[0084] S3. Different methods are used to calculate the interfacial tension coefficient of magnetic liquids according to different magnetic field strength ranges; when the magnetic field is a weak magnetic field, method one is used to calculate the interfacial tension coefficient of magnetic liquids, and when the magnetic field is a strong magnetic field, method two is used to calculate the interfacial tension coefficient of magnetic liquids.

[0085] Within a weak magnetic field range, it is assumed that the interfacial tension of the magnetic fluid does not change with the magnetic field strength.

[0086] The first method includes:

[0087] S101. Calculate the magnetic induction intensity in the magnetic fluid and obtain the first parameter through iterative calculation;

[0088] The formula for calculating the magnetic induction intensity in the magnetic fluid is formula (1):

[0089] (1)

[0090] in, The magnetic flux density within the magnetic fluid. The known permeability of free space;

[0091] The iterative formula for obtaining the first parameter through iterative calculation is formula (2):

[0092] (2)

[0093] in,

[0094]

[0095]

[0096] in, The first parameter is the iteration parameter. Boltzmann's constant, Given the temperature, Given the saturation magnetization of a known magnetic fluid, Let be the magnetic moment of a single magnetic particle in a known magnetic fluid.

[0097] S102. Calculate the second parameter and the magnetization intensity of the magnetic fluid based on the first parameter;

[0098] The formula for calculating the second parameter is formula (3):

[0099] (3)

[0100] in, The second parameter;

[0101] The formula for calculating the magnetization of a magnetic fluid is formula (4):

[0102] (4)

[0103] in, The magnetization intensity of the magnetic fluid;

[0104] S103. The magnetic field strength inside the magnetic fluid is calculated based on the critical magnetic field strength and the magnetization of the magnetic fluid.

[0105] The formula for calculating the magnetic field strength in a magnetic fluid is formula (5):

[0106] (5)

[0107] in, The magnetic field strength within the magnetic fluid;

[0108] S104. The third parameter is calculated based on the second parameter, the magnetic induction intensity in the magnetic liquid, and the magnetic field intensity in the magnetic liquid;

[0109] The formula for calculating the third parameter is formula (6):

[0110] (6)

[0111] in, This is the third parameter.

[0112] S105. The interfacial tension coefficient of the magnetic liquid under a weak magnetic field is calculated based on the third parameter and the magnetization intensity of the magnetic liquid.

[0113] The formula for calculating the interfacial tension coefficient of a magnetic fluid in a weak magnetic field is formula (7).

[0114] (7)

[0115] in, is the interfacial tension coefficient of the magnetic fluid under a weak magnetic field. It is the acceleration due to gravity. and The densities of the magnetic liquid and the first liquid are known quantities.

[0116] Within a strong magnetic field range, the relationship between the interfacial tension coefficient and the magnetic field strength must be considered.

[0117] The second method includes:

[0118] S201. Empty the liquid in the container, put a first liquid that is immiscible with the magnetic liquid to be tested in the container, and drip the droplet of the magnetic liquid to be tested into the first liquid.

[0119] S202, Increase the first power supply current to make the magnetic field strength generated by the Helmholtz coil greater than... Record the magnetic field strength at this time as ;

[0120] S203, The first camera and the second camera capture images when the magnetic field strength is... At that time, the interface deformation between the magnetic liquid and the first liquid in the container is recorded and transmitted to the computer. The computer processes the data to determine the magnetic field strength when it is... At that time, the longitudinal half-length b and the transverse half-length of the magnetic liquid droplet in the first liquid ratio And the contact angle size of the shape of the magnetic liquid droplet in the first liquid. ;

[0121] S204, Input the known density, viscosity, and permeability of the magnetic liquid, the known density, viscosity, and permeability of the first liquid, and the contact angle obtained by the computer into the computer. and magnetic field strength The computer calculates using a two-phase flow calculation method.

[0122] By inputting multiple different preset interfacial tension coefficients, the ratio of the longitudinal half-length to the transverse half-length of the magnetic liquid droplet shape in the first liquid corresponding to each preset interfacial tension coefficient is obtained. ;

[0123] Thus, the ratio of the longitudinal half-length to the transverse half-length of the magnetic liquid droplet's shape in the first liquid is obtained. The relationship curve between the interfacial tension coefficient and the interfacial tension coefficient is shown in curve l.

[0124] S205. On curve l, using interpolation, we obtain the result when the magnetic field strength is... The longitudinal half-length b and the transverse half-length of the magnetic liquid droplet in the first liquid are... The ratio is When, the interfacial tension coefficient of the corresponding magnetic fluid.

[0125] This method divides the effect of magnetic field on interfacial tension coefficient into a weak magnetic field before Rosensweig instability and a strong magnetic field above the threshold, enabling the measurement of interfacial tension coefficient under both magnetic field conditions on a single device. Utilizing experimental measurements of the shape of a magnetic liquid droplet in a solution incompatible with the magnetic liquid, supplemented by numerical calculations of the magnetic liquid droplet interface based on this shape, the interfacial tension coefficient corresponding to a given magnetic field is ultimately obtained. Furthermore, this invention calculates the interfacial tension coefficient, and compared to traditional tensiometer measurement methods, the results are unaffected by interfacial deformation, resulting in more accurate results.

[0126] The following points need to be explained:

[0127] (1) The accompanying drawings of the embodiments of the present invention only involve the structures involved in the embodiments of the present invention. Other structures can refer to the general design.

[0128] (2) For clarity, the thickness of layers or regions is enlarged or reduced in the drawings used to describe embodiments of the invention, i.e., these drawings are not drawn to scale. It is understood that when an element such as a layer, film, region or substrate is referred to as being “above” or “below” another element, the element may be “directly” located “above” or “below” the other element or there may be intermediate elements.

[0129] (3) Where there is no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other to obtain new embodiments.

[0130] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. The scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for measuring the interfacial tension coefficient of a magnetic liquid, characterized in that, The device includes a magnetic liquid interfacial tension coefficient measuring device. The device includes a horizontal base, a container placed on the base, the container containing the magnetic liquid to be measured and a first liquid that is immiscible with the magnetic liquid to be measured, a light source and a first camera respectively placed on the base and on both sides of the container, and a second camera placed directly above the container. The first camera and the second camera are electrically connected to a computer. A Helmholtz coil is placed on one side of the container, so that the container is placed at the center of a uniform magnetic field. The Helmholtz coil is electrically connected to a second power source. The method includes: S1. Gradually increase the magnetic field until Rosensweig instability occurs at the interface between the magnetic liquid and the first liquid, and record the magnetic field strength at this point. ; S2. Define the range of magnetic field strength; Set the magnetic field strength as When the magnetic field strength is less than or equal to the critical magnetic field strength, it is considered critical. At this time, the magnetic field is set as a weak magnetic field. When the magnetic field strength is greater than... At this time, the magnetic field is set to a strong magnetic field; S3. Calculate the interfacial tension coefficient of magnetic fluids using different methods depending on the range of magnetic field strength. When the magnetic field is weak, assuming that the interfacial tension of the magnetic liquid does not change with the magnetic field strength, Method 1 is used to calculate the interfacial tension coefficient of the magnetic liquid. When the magnetic field is strong, within the strong magnetic field range, the relationship between the interfacial tension coefficient and the magnetic field strength needs to be considered, and Method 2 is used to calculate the interfacial tension coefficient of the magnetic liquid. The experimental measurement results of the shape of the magnetic liquid droplet in another phase that is immiscible with the magnetic liquid are used, supplemented by the numerical calculation results of the interface of the magnetic liquid droplet based on the shape, to finally obtain the interfacial tension coefficient corresponding to a certain magnetic field.

2. The method for measuring the interfacial tension coefficient of magnetic liquids according to claim 1, characterized in that, The magnetic field is gradually increased as described in S1 until Rosensweig instability occurs at the interface between the magnetic liquid and the first liquid. The magnetic field strength at this point is recorded. ,include: By gradually increasing the current of the second power source, the magnetic field generated by the Helmholtz coil is gradually strengthened. The interface deformation between the magnetic liquid and the first liquid in the container is observed by the computer through the images captured by the first camera and the second camera.

3. The method for measuring the interfacial tension coefficient of magnetic liquids according to claim 1, characterized in that, The first method includes: S101. Calculate the magnetic induction intensity in the magnetic fluid and obtain the first parameter through iterative calculation; The calculation of the magnetic induction intensity within the magnetic fluid in step S101, and the iterative calculation to obtain the first parameter, includes: The formula for calculating the magnetic induction intensity in the magnetic fluid is formula (1): （1） in, The magnetic flux density within the magnetic fluid. The known permeability of free space; The iterative formula for obtaining the first parameter through iterative calculation is formula (2): （2） in, ； in, The first parameter is the iteration parameter. Boltzmann's constant, Given the temperature, Given the saturation magnetization of a known magnetic fluid, Let be the magnetic moment of a single magnetic particle in a known magnetic fluid; S102. Calculate the second parameter and the magnetization intensity of the magnetic fluid based on the first parameter; The step S102, which calculates the second parameter and the magnetization of the magnetic fluid based on the first parameter, includes: The formula for calculating the second parameter is formula (3): （3） in, This is the second parameter; The formula for calculating the magnetization of a magnetic fluid is formula (4): （4） in, The magnetization intensity of the magnetic fluid; S103. The magnetic field strength inside the magnetic fluid is calculated based on the critical magnetic field strength and the magnetization of the magnetic fluid. The calculation of the magnetic field strength within the magnetic fluid based on the critical magnetic field strength and the magnetization of the magnetic fluid in step S103 includes: The formula for calculating the magnetic field strength in a magnetic fluid is formula (5): （5） in, The magnetic field strength within the magnetic fluid; S104. The third parameter is calculated based on the second parameter, the magnetic induction intensity in the magnetic liquid, and the magnetic field intensity in the magnetic liquid; The step of S104, which calculates the third parameter based on the second parameter, the magnetic induction intensity in the magnetic fluid, and the magnetic field intensity in the magnetic fluid, includes: The formula for calculating the third parameter is formula (6): （6） in, It is the third parameter; S105. The interfacial tension coefficient of the magnetic liquid under a weak magnetic field is calculated based on the third parameter and the magnetization intensity of the magnetic liquid.

4. The method for measuring the interfacial tension coefficient of magnetic liquids according to claim 1, characterized in that, The second method includes: S201. Empty the liquid in the container, put a first liquid that is immiscible with the magnetic liquid to be tested in the container, and drip the droplet of the magnetic liquid to be tested into the first liquid. S202, Increase the second power supply current to make the magnetic field strength generated by the Helmholtz coil greater than... Record the magnetic field strength at this time as ; S203, The first camera and the second camera capture images when the magnetic field strength is... At that time, the interface deformation between the magnetic liquid and the first liquid in the container is recorded and transmitted to the computer. The computer processes the data to determine the magnetic field strength when it is... At that time, the longitudinal half-length of the shape of the magnetic liquid droplet in the first liquid b With horizontal half length ratio And the contact angle size of the shape of the magnetic liquid droplet in the first liquid. ; S204, Input the known density, viscosity, and permeability of the magnetic liquid, the known density, viscosity, and permeability of the first liquid, and the contact angle obtained by the computer into the computer. and magnetic field strength The computer calculates using a two-phase flow calculation method. By inputting multiple different preset interfacial tension coefficients, the ratio of the longitudinal half-length to the transverse half-length of the magnetic liquid droplet shape in the first liquid corresponding to each preset interfacial tension coefficient is obtained. ; Thus, the ratio of the longitudinal half-length to the transverse half-length of the magnetic liquid droplet's shape in the first liquid is obtained. Relationship curve between interfacial tension coefficient l ; S205, on the curve l Above, using an interpolation method, we obtain the result when the magnetic field strength is... The longitudinal half-length of the shape of the magnetic liquid droplet in the first liquid b With horizontal half length The ratio is When, the interfacial tension coefficient of the corresponding magnetic fluid.

5. The method for measuring the interfacial tension coefficient of magnetic liquids according to claim 3, characterized in that, The interfacial tension coefficient of the magnetic liquid calculated based on the third parameter and the magnetization of the magnetic liquid in S105 when the magnetic field is weak includes: The formula for calculating the interfacial tension coefficient of a magnetic fluid in a weak magnetic field is formula (7). （7） in, is the interfacial tension coefficient of the magnetic fluid under a weak magnetic field. It is the acceleration due to gravity. and The densities of the magnetic liquid and the first liquid are known quantities.

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