CN113009388B - Magnetic liquid magnetization relaxation time measuring device and method - Google Patents

Magnetic liquid magnetization relaxation time measuring device and method Download PDF

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CN113009388B
CN113009388B CN202110294989.1A CN202110294989A CN113009388B CN 113009388 B CN113009388 B CN 113009388B CN 202110294989 A CN202110294989 A CN 202110294989A CN 113009388 B CN113009388 B CN 113009388B
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CN113009388A (en
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杨文明
刘北英
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University of Science and Technology Beijing USTB
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    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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    • G01R33/12—Measuring magnetic properties of articles or specimens of solids or fluids
    • G01R33/1215—Measuring magnetisation; Particular magnetometers therefor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
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Abstract

The invention provides a device and a method for measuring the magnetization relaxation time of magnetic liquid, belonging to the technical field of characterization of physical characteristics of magnetic liquid. The device comprises a uniform magnetic field generator, a magnetic field sensor, an inner cylinder, an outer cylinder, a liquid injection hole, an O-shaped ring, an end cover, a snap spring, a shell, a bearing, a sleeve, a supporting plate, a supporting seat, a coupler, a speed increaser, a gear, a shaft, a motor, a support and a bottom plate. The device can realize simple and convenient low-cost measurement of the magnetization relaxation time of the magnetic liquid.

Description

Magnetic liquid magnetization relaxation time measuring device and method
Technical Field
The invention relates to the technical field of characterization of physical characteristics of magnetic liquid, in particular to a device and a method for measuring magnetization relaxation time of magnetic liquid.
Background
The magnetic liquid is a colloid system formed by suspending nano-grade ferromagnetic particles coated with a surfactant in a liquid medium, and is widely applied to the technical fields of sealing, lubricating and other engineering. In practical application, when the direction of the external magnetic field is not consistent with the direction of the magnetic moment of the particles in the magnetic liquid, the magnetic moment is turned to the direction of the magnetic field under the action of the magnetic moment, and the process is called magnetization relaxation and is characterized by magnetization relaxation time. In a theoretical model of magnetic liquid sealing and lubrication in which magnetization relaxation is considered, the inverse of magnetization relaxation time is a coefficient of a key term therein, and therefore, accurate measurement of magnetization relaxation time of a specific magnetic liquid is key to accurate establishment of the theoretical model.
In the prior art, the size of the magnetic particles in the magnetic liquid has to be known for obtaining the magnetization relaxation time. In practical magnetic liquids, however, the particle size is not a single value, but rather has a wide size distribution. Therefore, the conventional means for obtaining the magnetization relaxation time is to measure the size distribution of magnetic particles in the magnetic liquid by using a dynamic light scattering or small angle neutron scattering method, and then calculate by using a theoretical expression of the magnetization relaxation time to obtain a final result. It can be seen that the conventional approach is complex and costly. There is therefore a need for a relatively simple and low cost method of measuring the magnetization relaxation time of a magnetic liquid.
Disclosure of Invention
The invention aims to provide a device and a method for measuring the magnetization relaxation time of a magnetic liquid.
The device comprises a uniform magnetic field generator, a magnetic field sensor, an outer cylinder, an inner cylinder, a liquid injection hole, an O-shaped ring, a first end cover, a second end cover, a snap spring, a shell, a first bearing, a second bearing, a sleeve, a supporting plate, a supporting seat, a first coupler, a second coupler, a speed increaser, a first gear, a second gear, a shaft, a motor, a support and a bottom plate, wherein the uniform magnetic field generator is arranged outside the shell, a gap for filling magnetic liquid is formed between the outer cylinder and the inner cylinder, the magnetic field sensor is arranged inside the inner cylinder, the outer cylinder, the O-shaped ring, the inner cylinder and the first end cover are sequentially connected, the outer cylinder and the inner cylinder are tightly connected by screws, the inner ring of the first bearing is arranged close to a boss of the outer cylinder, the snap spring is arranged at a groove on the outer side surface of the inner cylinder, the inner ring of the second bearing is arranged close to the snap spring, the first end cover is fixed on the inner cylinder by screws to tightly press the second bearing, the first bearing, the sleeve and the second bearing are sequentially arranged close to the boss of the shell, the second end cover is fixed on the upper end face of the shell through screws, the outer ring of the second bearing is compressed, the shell, the supporting plate, the supporting seat and the bottom plate are sequentially connected, the shell is arranged on the upper end face of the supporting plate through screws, the supporting plate is arranged on the upper end face of the supporting seat through screws, the supporting seat is arranged on the upper surface of the bottom plate through screws, the motor, the second coupler, the shaft and the second gear are sequentially connected, the second gear is meshed with the first gear, the speed increaser, the first coupler and the outer cylinder bottom extension shaft are sequentially connected, the speed increaser is arranged at the step of an inner hole of the supporting plate through screws, the first coupler is connected with the high-speed output end of the speed increaser, the first gear is connected with the low-speed input end of the speed increaser, and the motor is fixedly connected with the bottom plate through a support.
The liquid injection hole is positioned above the inner cylinder.
The outer cylinder, the inner cylinder, the shell and the sleeve are made of non-magnetic materials; the axial dimensions of the outer cylinder and the inner cylinder meet the following requirements: the longitudinal length of the gap filled with the magnetic liquid is larger than the diameter by at least 6 times, and the radial sizes of the outer cylinder and the inner cylinder meet the following requirements: the gap width of the filled magnetic liquid is made to be at most 1/10 of the inner diameter of the outer cylinder.
The longitudinal distance between the first bearing, the clamp spring and the central position of the gap filled with the magnetic liquid satisfies the following conditions: the distortion of a magnetic field in the magnetic liquid caused by the first bearing, the clamp spring and the second bearing is not more than 5 percent; the first bearing and the second bearing comprise a ball bearing, a tapered roller bearing and an end face ball bearing.
The position of the uniform magnetic field generator satisfies: the direction of the generated magnetic field is perpendicular to the rotation axis of the magnetic liquid, and the magnetic liquid is positioned in the range of a uniform magnetic field; the magnetic field generated by the uniform magnetic field generator enables the magnetic field intensity at the position of the magnetic liquid to be within the linear magnetization range of the magnetic liquid; the uniform magnetic field generator comprises a Helmholtz coil, a Maxwell coil, a Fanselau coil and a permanent magnet group.
The first gear and the second gear are bevel gears; the first coupler and the second coupler are flexible couplers; the motor is a speed-adjustable motor.
The probe of the magnetic field sensor is positioned in the inner cylinder and is used for measuring the magnetic induction intensity in the direction perpendicular to the magnetic field generated by the uniform magnetic field generator, and the magnetic field sensor comprises a Hall sensor and a Tesla meter.
The method specifically comprises the following steps:
s1: injecting the magnetic liquid to be detected into a gap between the outer cylinder and the inner cylinder through the liquid injection hole;
s2: the uniform magnetic field generator generates magnetic field with intensity of H at the position of the magnetic liquidextA uniform magnetic field of (a);
s3: the magnetic liquid in the gap between the inner cylinder and the outer cylinder makes integral rigid rotation, generates magnetization perpendicular to the direction of the external magnetic field in the magnetic liquid, and induces the magnetic field intensity H perpendicular to the direction of the external magnetic field in the inner cylinder0；
S4: according to the magnetic field intensity H measured by the magnetic field sensor0The magnetic field intensity H generated by the uniform magnetic field generator at the position of the magnetic liquidextCalculating the magnetization relaxation time of the magnetic liquid by using a relational expression; or from the magnetic field strength H measured by the magnetic field sensor0Uniform magnetic fieldMagnetic field strength H generated by the field generator at the location of the magnetic liquidextAnd calculating the magnetization relaxation time of the magnetic liquid by using an analytical expression.
Wherein the relation in S4 is the magnetic field intensity H derived according to the basic physical law0The relationship between the rotation speed of the magnetic liquid and the magnetization relaxation time,
Figure BDA0002983998570000031
wherein τ is the magnetization relaxation time of the magnetic liquid, Ω is the rotation speed of the magnetic liquid, χ is the magnetic susceptibility of the magnetic liquid, R2Is the inner radius of the outer cylinder, R1Is the outer radius of the inner cylinder.
The analytical expression is a polynomial which is obtained by fitting after measuring the induction fields of various magnetic liquids on the experimental device and meets the preset precision requirement;
Figure BDA0002983998570000032
wherein τ is the magnetization relaxation time of the magnetic liquid, Ω is the rotation speed of the magnetic liquid, χ is the magnetic susceptibility of the magnetic liquid, and f (χ) is a function of the magnetic susceptibility.
The technical scheme of the invention has the following beneficial effects:
in the scheme, the magnetization relaxation time is calculated by measuring the magnetic field strength generated in the rigid rotating magnetic liquid ring and perpendicular to the direction of the external magnetic field and by an analytic expression obtained by deriving the relationship or fitting a plurality of groups of experiments according to the basic physical law, so that the magnetization relaxation time of the magnetic liquid can be simply and conveniently measured at low cost.
Drawings
FIG. 1 is a front view of an apparatus according to an embodiment of the present invention;
FIG. 2 is a top view of an apparatus according to an embodiment of the present invention;
fig. 3 is a left side view of an apparatus according to an embodiment of the present invention.
Wherein: 1-magnetic liquid, 2-outer cylinder, 3-inner cylinder, 5-O-shaped ring, 6-snap spring, 7-shell, 9-sleeve, 11-second end cover, 13-first end cover, 16-supporting disk, 18-supporting seat, 19-bottom plate, 21-first coupling, 23-speed increaser, 25-shaft, 26-second coupling, 27-motor, 28-bracket, 31-liquid injection hole, 81-first bearing, 82-second bearing, 100-magnetic field sensor, 101-uniform magnetic field generator, 241-first gear, 242-second gear.
Detailed Description
In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments.
The invention provides a magnetic liquid magnetization relaxation time measuring device and a method thereof, as shown in fig. 1, fig. 2 and fig. 3.
The device comprises a uniform magnetic field generator 101, a magnetic field sensor 100, an outer cylinder 2, an inner cylinder 3, a liquid injection hole 31, an O-shaped ring 5, a first end cover 13, a second end cover 11, a clamp spring 6, a shell 7, a first bearing 81, a second bearing 82, a sleeve 9, a supporting disc 16, a supporting seat 18, a first coupler 21, a second coupler 26, a speed increaser 23, a first gear 241, a second gear 242, a shaft 25, a motor 27, a support 28 and a bottom plate 19.
A uniform magnetic field generator 101 is arranged outside the shell 7, a gap filled with magnetic liquid 1 is formed between the outer cylinder 2 and the inner cylinder 3, and a magnetic field sensor 100 is arranged inside the inner cylinder 3.
The outer cylinder 2, the O-shaped ring 5, the inner cylinder 3 and the first end cover 13 are connected in sequence, and the outer cylinder 2 and the inner cylinder 3 are fastened and connected through screws; the inner ring of the first bearing 81 is arranged close to the boss of the outer cylinder 2, the clamp spring 6 is arranged at the groove on the outer side surface of the inner cylinder 3, the inner ring of the second bearing 82 is arranged close to the clamp spring 6, the first end cover 13 is fixed on the inner cylinder 3 by screws, and the second bearing 82 is pressed tightly; the first bearing 81, the sleeve 9 and the second bearing 82 are sequentially arranged close to the boss of the shell 7, the second end cover 11 is fixed on the upper end face of the shell 7 by screws, and the outer ring of the second bearing 82 is pressed tightly; the shell 7, the supporting disc 16, the supporting seat 18 and the bottom plate 19 are sequentially connected, the shell 7 is installed on the upper end face of the supporting disc 16 through screws, the supporting disc 16 is installed on the upper end face of the supporting seat 18 through screws, and the supporting seat 18 is installed on the upper surface of the bottom plate 19 through screws; the motor 27, the second coupler 26, the shaft 25 and the second gear 242 are sequentially connected, the second gear 242 is meshed with the first gear 241, the speed increaser 23, the first coupler 21 and an extending shaft at the bottom of the outer cylinder 2 are sequentially connected, the speed increaser 23 is installed at the step of an inner hole of the supporting plate 16 by using screws, wherein the first coupler 21 is connected with the high-speed output end of the speed increaser 23, and the first gear 241 is connected with the low-speed input end of the speed increaser 23; the motor 27 is fixedly connected to the base plate 19 by a bracket 28, and the bracket 28 is mounted on the upper surface of the base plate 19 by screws.
Annotate liquid hole 31 and be located inner cylinder 3 top, will await measuring magnetic fluid 1 and annotate the liquid hole 31 through annotating during the measurement and pour into the clearance between outer cylinder 2 and inner cylinder 3 into, at the injection in-process, place in outer cylinder 2 bottom with a permanent magnet, can be favorable to magnetic fluid 1 to flow into the clearance.
The outer cylinder 2, the inner cylinder 3, the shell 7, the sleeve 9 and the screw are all made of non-magnetic materials.
The axial dimensions of the outer cylinder 2 and the inner cylinder 3 satisfy: the longitudinal length of the gap filled with the magnetic liquid 1 is larger than the diameter by more than 6 times, and the radial sizes of the outer cylinder 2 and the inner cylinder 3 meet the following requirements: the gap width of the magnetic liquid 1 filled is made to be at most 1/10 of the inner diameter of the outer cylinder 2.
The longitudinal distance between the first bearing 81, the clamp spring 6, the second bearing 82 and the central position of the gap filled with the magnetic liquid 1 satisfies the following conditions: the distortion of the magnetic field in the magnetic liquid 1 caused by the first bearing 81, the clamp spring 6 and the second bearing 82 is not more than 5%.
The uniform magnetic field generator 101 is used to generate a certain magnetic field strength H at the location of the magnetic liquid 1extThe position of the uniform magnetic field generator 101 satisfies: the direction of the generated magnetic field is perpendicular to the rotation axis of the magnetic liquid 1, and the magnetic liquid 1 is located in the range of the uniform magnetic field, and the magnetic field generated by the uniform magnetic field generator 101 satisfies: the magnetic field strength at the position of the magnetic liquid 1 is made to be within the linear magnetization range of the magnetic liquid 1.
The first gear 241 and the second gear 242 are bevel gears.
The magnetic liquid 1 filled in the gap between the outer cylinder 2 and the inner cylinder 3 is driven by the motor 27, the second coupler 26, the shaft 25, the second gear 242, the first gear 241, the speed increaser 23, the first coupler 21, the outer cylinder 2 and the inner cylinder 3 to do integral rigid rotation motion, due to the magnetization relaxation effect of the magnetic liquid, the magnetization intensity perpendicular to the direction of the external magnetic field is generated in the magnetic liquid 1, and the magnetization intensity induces the magnetic field intensity H perpendicular to the direction of the external magnetic field in the inner cylinder 30。
The probe of the magnetic field sensor 100 is located inside the inner cylinder 3 for measuring the magnetic induction in a direction perpendicular to the magnetic field generated by the magnetic field generator 101.
Based on the magnetic field strength H measured by the magnetic field sensor 1000The magnetic field intensity H generated by the uniform magnetic field generator 101 at the position of the magnetic liquid 1extCalculating the magnetization relaxation time of the magnetic liquid 1 by using the rotation speed of the magnetic liquid 1 and a relational expression, wherein the relational expression is the magnetic field intensity H obtained by derivation according to the basic physical law0The rotational speed of the magnetic liquid 1 and the magnetization relaxation time.
Wherein the relation is:
Figure BDA0002983998570000061
τ is the magnetization relaxation time of the magnetic liquid, Ω is the rotation speed of the magnetic liquid, χ is the magnetic susceptibility of the magnetic liquid, R2Is the inner radius of the outer cylinder, R1Is the outer radius of the inner cylinder.
Or according to the magnetic field intensity H measured by the magnetic field sensor 1000The magnetic field intensity H generated by the uniform magnetic field generator 101 at the position of the magnetic liquid 1extAnd calculating the magnetization relaxation time of the magnetic liquid 1 by using the rotating speed of the magnetic liquid 1 and an analytical expression, wherein the analytical expression is a polynomial which meets the preset precision requirement and is obtained by fitting after measuring the induced magnetic fields of various magnetic liquids on the experimental device.
Wherein, the analytic expression can be obtained by the following method:
s11: selecting more than three known magnetization relaxation times tauiThe magnetic liquid is used as a calibration magnetic liquid, and the magnetic susceptibility χ of the magnetic liquid is measuredi(wherein i represents the i-th magnetic liquid);
s12: the device of the invention is used for measuring and obtaining the rotation speed omega of each magnetic liquid and a certain external magnetic field H of each magnetic liquidextInduced magnetic field strength H under the condition0，i；
S13: setting a polynomial of the function f (χ) of magnetic susceptibility and the magnetic susceptibility γ:
s14: χ obtained according to steps S11 and S12iAnd f (χ)i)＝H0，i/(HextΩτi) Fitting the polynomial by a least square method to obtain parameters of the polynomial;
s15: establishing the magnetization relaxation time and function f (x) of the magnetic liquid and the external magnetic field HextInduced magnetic field H0And the magnetic liquid rotation speed omega:
Figure BDA0002983998570000062
s16: and comparing the magnetization relaxation time output by the expression with the magnetization relaxation time of the calibrated magnetic liquid, finishing the fitting if the error between the magnetization relaxation time output by the expression and the magnetization relaxation time of the calibrated magnetic liquid is less than or equal to a preset threshold, otherwise, correcting the degree of the polynomial and returning to S14.
For the two methods for calculating the magnetization relaxation time of the magnetic liquid, experiments can be carried out under the condition of a plurality of magnetic liquid rotating speeds during measurement, and the average value of the results is taken as the final result of the magnetization relaxation time, so that the measurement error can be reduced.
In one possible implementation, the first bearing 81 and the second bearing 82 comprise: ball bearings, tapered roller bearings, and face ball bearings.
In one possible implementation, the uniform magnetic field generator 101 comprises: helmholtz coil, Maxwell coil, Fanselau coil, permanent magnet group.
In one possible implementation, the magnetic field sensor 100 includes: hall sensors, teslameters.
In one possible implementation, the first coupling 21 and the second coupling 26 are flexible couplings.
In one possible implementation, the motor 27 is a variable speed motor.
Those skilled in the art will appreciate that all or part of the steps of implementing the above method embodiments may be implemented by hardware associated with program instructions, and the program may be stored in a computer-readable storage medium, and when executed, the program performs the steps comprising the above method embodiments, and the storage medium comprises: various media that can store program codes, such as ROM, RAM, magnetic or optical disks.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (10)

1. A magnetic liquid magnetization relaxation time measuring apparatus characterized in that: the magnetic field generator comprises a uniform magnetic field generator (101), a magnetic field sensor (100), an outer cylinder (2), an inner cylinder (3), a liquid injection hole (31), an O-shaped ring (5), a first end cover (13), a second end cover (11), a clamp spring (6), a shell (7), a first bearing (81), a second bearing (82), a sleeve (9), a supporting plate (16), a supporting seat (18), a first coupler (21), a second coupler (26), a speed increaser (23), a first gear (241), a second gear (242), a shaft (25), a motor (27), a support (28) and a bottom plate (19), the uniform magnetic field generator (101) is arranged outside the shell (7), a gap for filling magnetic liquid (1) is formed between the outer cylinder (2) and the inner cylinder (3), the magnetic field sensor (100) is arranged inside the inner cylinder (3), the outer cylinder (2), the O-shaped ring (5), The inner cylinder (3) and the first end cover (13) are sequentially connected, the outer cylinder (2) is tightly connected with the inner cylinder (3) through screws, the inner ring of the first bearing (81) is tightly installed at a boss of the outer cylinder (2), the clamp spring (6) is installed at a groove of the outer side surface of the inner cylinder (3), the inner ring of the second bearing (82) is tightly installed at the clamp spring (6), the first end cover (13) is fixed on the inner cylinder (3) through screws and tightly presses the second bearing (82), the first bearing (81), the sleeve (9) and the second bearing (82) are sequentially installed at a boss of the shell (7) through tightly pressing the second bearing (82), the second end cover (11) is fixed on the upper end surface of the shell (7) through screws and tightly presses the outer ring of the second bearing (82), the shell (7), the supporting disk (16), the supporting seat (18) and the bottom plate (19) are sequentially connected, the shell (7) is installed on the upper end surface of the supporting disk (16) through screws, the supporting disc (16) is arranged on the upper end face of the supporting disc (18) through screws, the supporting disc (18) is arranged on the upper surface of the bottom plate (19) through screws, the motor (27), the second coupler (26), the shaft (25) and the second gear (242) are sequentially connected, the second gear (242) is meshed with the first gear (241), the speed increaser (23), the first coupler (21) and an extending shaft at the bottom of the outer cylinder (2) are sequentially connected, the speed increaser (23) is arranged at an inner hole step of the supporting disc (16) through screws, the first coupler (21) is connected with the high-speed output end of the speed increaser (23), the first gear (241) is connected with the low-speed input end of the speed increaser (23), and the motor (27) is fixedly connected with the bottom plate (19) through a support (28).
2. The magnetic liquid magnetization relaxation time measurement device according to claim 1, characterized in that: the liquid injection hole (31) is positioned above the inner cylinder (3).
3. The magnetic liquid magnetization relaxation time measurement device according to claim 1, characterized in that: the outer cylinder (2), the inner cylinder (3), the shell (7) and the sleeve (9) are made of non-magnetic materials; the axial dimensions of the outer cylinder (2) and the inner cylinder (3) satisfy: the longitudinal length of the gap filled with the magnetic liquid (1) is larger than the diameter by at least 6 times, and the radial sizes of the outer cylinder (2) and the inner cylinder (3) meet the following requirements: the width of the gap filled with the magnetic liquid (1) is made to be at most 1/10 of the inner diameter of the outer cylinder (2).
4. The magnetic liquid magnetization relaxation time measurement device according to claim 1, characterized in that: the longitudinal distance between the first bearing (81), the clamp spring (6) and the second bearing (82) and the central position of the gap filled with the magnetic liquid (1) satisfies the following conditions: the distortion of the magnetic field in the magnetic liquid (1) caused by the first bearing (81), the clamp spring (6) and the second bearing (82) is not more than 5 percent; the first bearing (81) and the second bearing (82) are both one of a ball bearing, a tapered roller bearing and an end face ball bearing.
5. The magnetic liquid magnetization relaxation time measurement device according to claim 1, characterized in that: the position of the uniform magnetic field generator (101) satisfies: the direction of the generated magnetic field is perpendicular to the rotation axis of the magnetic liquid (1), and the magnetic liquid (1) is positioned in the range of a uniform magnetic field; the magnetic field generated by the uniform magnetic field generator (101) enables the magnetic field intensity at the position of the magnetic liquid (1) to be positioned in the linear magnetization range of the magnetic liquid (1); the uniform magnetic field generator (101) is one of a Helmholtz coil, a Maxwell coil, a Fanselau coil and a permanent magnet group.
6. The magnetic liquid magnetization relaxation time measurement device according to claim 1, characterized in that: the first gear (241) and the second gear (242) are bevel gears; the first coupling (21) and the second coupling (26) are flexible couplings; the motor (27) is a speed-adjustable motor.
7. The magnetic liquid magnetization relaxation time measurement device according to claim 1, characterized in that: the probe of the magnetic field sensor (100) is positioned in the inner cylinder (3) and is used for measuring the magnetic induction intensity in the direction perpendicular to the magnetic field generated by the uniform magnetic field generator (101), and the magnetic field sensor (100) is one of a Hall sensor and a Tesla meter.
8. A method of applying the magnetic liquid magnetization relaxation time measurement apparatus according to claim 1, characterized in that: the method comprises the following steps:
s1: injecting the magnetic liquid (1) to be detected into a gap between the outer cylinder (2) and the inner cylinder (3) through the liquid injection hole (31);
s2: the uniform magnetic field generator generates magnetic field with intensity H at the position of the magnetic liquid (1)extA uniform magnetic field of (a);
s3: the magnetic liquid in the gap between the inner cylinder (3) and the outer cylinder (2) does integral rigid rotation motion, the magnetization intensity vertical to the direction of the external magnetic field is generated in the magnetic liquid (1), and the magnetization intensity induces the magnetic field intensity H vertical to the direction of the external magnetic field in the inner cylinder (3)0；
S4: based on the magnetic field intensity H measured by the magnetic field sensor (100)0The magnetic field intensity H generated by the uniform magnetic field generator (101) at the position of the magnetic liquidextCalculating the magnetization relaxation time of the magnetic liquid by using a relational expression; or from the magnetic field strength H measured by the magnetic field sensor0The magnetic field intensity H generated by the uniform magnetic field generator at the position of the magnetic liquidextAnd calculating the magnetization relaxation time of the magnetic liquid by using an analytical expression.
9. The method for applying a magnetic liquid magnetization relaxation time measuring device according to claim 8, characterized in that: the relation in S4 is the magnetic field intensity H derived according to the basic physical law0The relationship between the rotation speed of the magnetic liquid and the magnetization relaxation time is as follows:
Figure FDA0003395187650000031
wherein τ is the magnetization relaxation time of the magnetic liquid, Ω is the rotation speed of the magnetic liquid, χ is the magnetic susceptibility of the magnetic liquid, R2Is the inner radius of the outer cylinder, R1Is the outer radius of the inner cylinder.
10. The method for applying a magnetic liquid magnetization relaxation time measuring device according to claim 8, characterized in that: the analytical expression in S4 is a polynomial that satisfies a predetermined accuracy requirement and is obtained by fitting after measuring the induced magnetic fields of the plurality of magnetic liquids on the magnetic liquid magnetization relaxation time measuring device,
Figure FDA0003395187650000032
wherein τ is the magnetization relaxation time of the magnetic liquid, Ω is the rotation speed of the magnetic liquid, χ is the magnetic susceptibility of the magnetic liquid, and f (χ) is a function of the magnetic susceptibility.
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CN108267407A (en) * 2018-01-29 2018-07-10 中国人民解放军国防科技大学 Device and method for measuring transverse spin relaxation time of alkali metal atoms
CN109932381A (en) * 2018-09-10 2019-06-25 苏州大学 A kind of longitudinal relaxation time measuring method and device

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KR100618382B1 (en) * 2005-05-03 2006-08-31 삼성전자주식회사 Method for measuring blood nmr relaxation time and apparatus using the same
SE529474C2 (en) * 2006-04-19 2007-08-21 Imego Ab Detecting magnetic response changes of a magnetic particle by measuring characteristic rotation time of magnetic particle, and measuring hydrodynamic volume of particle by detecting change of magnetization of the particle

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Publication number Priority date Publication date Assignee Title
CN101963567A (en) * 2010-09-21 2011-02-02 中国兵器工业第五二研究所 Method and device for testing magnetic viscosity of magnetic liquid
CN108267407A (en) * 2018-01-29 2018-07-10 中国人民解放军国防科技大学 Device and method for measuring transverse spin relaxation time of alkali metal atoms
CN109932381A (en) * 2018-09-10 2019-06-25 苏州大学 A kind of longitudinal relaxation time measuring method and device

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