CN114397050A - Magnetic suspension type friction resistance measuring device - Google Patents
Magnetic suspension type friction resistance measuring device Download PDFInfo
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- CN114397050A CN114397050A CN202111516511.5A CN202111516511A CN114397050A CN 114397050 A CN114397050 A CN 114397050A CN 202111516511 A CN202111516511 A CN 202111516511A CN 114397050 A CN114397050 A CN 114397050A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
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Abstract
The invention discloses a magnetic suspension type friction resistance measuring device which comprises a floating plane assembly and a support assembly used for supporting the plane assembly, wherein the support assembly is connected with an electromagnetic suspension control system. The magnetic suspension type friction resistance measuring device can reduce the interference of the supporting device to the floating surface to the maximum extent, reduce the moving additional resistance of the floating plane and improve the measuring precision.
Description
Technical Field
The invention belongs to the technical field of magnetic suspension, and particularly relates to a magnetic suspension type friction resistance measuring device.
Background
Several studies have shown that: the friction resistance of transportation means such as airplanes, automobiles, ships and the like in the running process is reduced, the energy consumption can be greatly reduced, and the aims of energy conservation and emission reduction are achieved. Flow control experiments are an important means for searching for drag reduction technology, and the accurate acquisition of the frictional resistance generated by the surface of the measured object in the experiments is important for understanding and improving the performance of the system.
At present, the friction resistance measured in the drag reduction experiment under the low flow rate experiment condition is small, and the precision requirement is relatively high (10)-1N/m2Level), which results in the measurement value of the existing experimental measurement equipment having great uncertainty and increases the difficulty of the experimental result reproduction in the scientific research process, therefore, how to accurately measure the frictional resistance of the surface of the measured object becomes a difficult problem in the flow control research process, and how to measure the frictional resistance of the fluid under the condition of applying different flow control methods needs to be solved urgentlyTo a problem of (a).
The existing fluid resistance measurement methods are generally classified into indirect measurement methods and direct measurement methods. The indirect measurement method can be mainly divided into measurement based on a velocity profile and measurement based on heat convection heat exchange according to the measurement principle. The method based on the velocity profile measurement is provided on the basis of a classical turbulent boundary layer layering model, turbulent friction resistance is calculated according to the relationship between the velocity profile and the resistance, but partial coefficients used for calculation are different due to different flow conditions, logarithmic region boundaries are not very clear, and the resistance measurement and calculation also have certain subjectivity; the technology of heat convection based heat exchange is mainly represented by a hot film measurement technology, the temperature change of a hot film sensor is in a linear relation with the conducted heat, so that the wall friction resistance and an electric signal are related, the frequency response is very high, but when some active flow control (such as plasma flow control) is applied, the temperature of fluid is increased by the heat injected by the active flow control, and the measured data are seriously influenced. The direct measurement method mainly utilizes a floating type force measuring balance for measurement, and as the name suggests, the floating type force measuring balance suspends the surface to be measured by using a certain method and acts on a high-precision pull pressure sensor so as to reduce the interference of a measuring device on a floating surface as much as possible. The initial floating type force measuring balance is supported by a mechanical structure, and then the balance supported by high-pressure air and liquid medium appears, but the interference of the supporting device on the measurement precision cannot be completely eliminated no matter the high-pressure air, the liquid medium or the mechanical structure exists.
Magnetic levitation technology is used as a non-contact supporting mode, and a new direction is pointed out for eliminating interference of a supporting structure. The magnetic suspension technology is a technology for overcoming gravity to achieve suspension by utilizing magnetic force, and the following three types of magnets can be applied to suspension: the electromagnet can realize active magnetic control and realize stable support of the floating element compared with the permanent magnet and the superconducting magnet because the electromagnet controls the strength of a magnetic field through current.
Disclosure of Invention
The invention aims to provide a magnetic suspension type friction resistance measuring device which can reduce the interference of a supporting device on a floating surface to the greatest extent, reduce the moving additional resistance of the floating surface and improve the measuring precision.
The invention adopts the technical scheme that the magnetic suspension type friction resistance measuring device comprises a floating plane component and a support component for supporting the plane component, wherein the support component is connected with an electromagnetic suspension control system.
The present invention is also characterized in that,
the floating plane assembly comprises a floating panel, two opposite sides of the floating panel are respectively provided with an installation platform with an L-shaped cross section, each installation platform comprises a vertical connecting plate and a horizontal installation plate, the vertical connecting plates are connected with the floating panel, and the upper surface of each horizontal installation plate is provided with a steel plate with a concave cross section; the floating panel is located above the bracket assembly.
The bracket component comprises an inverted T-shaped base, a lower fixing plate is arranged at the top of the base, an upper fixing plate is arranged above the lower fixing plate, and the lower fixing plate and the upper fixing plate are connected through a plurality of bolts;
the electromagnetic suspension control system comprises four electromagnetic suspension control units, each electromagnetic suspension control unit comprises an operational amplifier, the output end of the operational amplifier is connected with an electromagnetic coil, the positive and negative power ends of the operational amplifier are connected with a direct current power supply, the electromagnetic coil is also connected with the direct current power supply, and the negative electrode of the operational amplifier is grounded; one input end of the operational amplifier is sequentially connected with a PAC chip, a singlechip and an eddy current displacement sensor; the other input end of the operational amplifier is respectively connected with a resistor R1And a resistance R2Resistance R1The output end of the operational amplifier is also connected; resistance R2One end is grounded;
the electromagnetic suspension control system also comprises four U-shaped magnetic cores uniformly arranged between the lower fixing plate and the upper fixing plate, each U-shaped magnetic core is wound with an electromagnetic coil, and one U-shaped magnetic core and one electromagnetic coil form an electromagnet; every two electromagnets are in a group and are positioned right above the steel plate, and the end parts of the two ends of each U-shaped magnetic core are positioned right above the two bosses of the steel plate; the top end part of the electromagnetic coil penetrates through the upper fixing plate; the four eddy current displacement sensors are uniformly arranged on the upper fixing plate; and the upper fixing plate is also provided with a pulling pressure sensor. The DC power supply has a voltage of 24-48V and a power of 250-500W.
The magnetic core is made of silicon steel sheets, the coil is 3000-6000 circles, and the diameter of the enameled wire is 0.7 mm.
The measuring range of the eddy current displacement sensor is 12.5mm, and the linearity error is less than or equal to +/-1%.
The pull pressure sensor is an S-shaped pull pressure sensor, the measuring range is 1N, and the response frequency is 1 kHz.
The invention has the beneficial effects that:
(1) the device of the invention provides a novel floating plane supporting mode, reduces the measurement interference of the supporting device on the floating plane by utilizing the magnetic suspension technology, and improves the measurement precision of the frictional resistance and the repeatability of the experiment.
(2) Compared with the traditional floating balance, the device is insensitive to environmental factors such as air humidity, temperature and the like, and has better adaptability to the environment.
(3) The device can be suitable for measuring the frictional resistance in different wind speed ranges, and has strong applicability.
Drawings
FIG. 1 is a schematic structural diagram of a magnetic levitation type frictional resistance measuring apparatus according to the present invention;
FIG. 2 is a front view of the magnetic levitation type frictional resistance measuring apparatus of the present invention;
FIG. 3 is a right side view of the magnetic levitation type frictional resistance measuring apparatus of the present invention;
FIG. 4 is a schematic cross-sectional view B-B of the magnetic levitation type frictional resistance measuring apparatus of the present invention;
FIG. 5 is an A-A section working state diagram of the magnetic suspension type frictional resistance measuring device in the actual flow field;
FIG. 6 is an enlarged view at J of FIG. 5;
FIG. 7 is a schematic view showing the connection relationship of an electromagnetic levitation control unit in the magnetic levitation type frictional resistance measuring apparatus of the present invention.
Fig. 8 is a front view of the magnetic levitation type frictional resistance measuring apparatus of the present invention in a stationary state.
In the figure, 1, a floating plane component, 2, an electromagnetic coil, 3, a magnetic core, 4, an eddy current displacement sensor, 5, a lower fixing plate, 6, a steel plate, 7, a tension pressure sensor, 8, real incoming current, 9, frictional resistance, 10, an electromagnetic suspension controller, 11, a base, 12, an upper fixing plate, 13, an operational amplifier, 14, a direct current power supply, 15, a PAC chip and 16, a singlechip;
1-1 part of floating panel, 1-2 parts of mounting table, 1-2-1 parts of vertical connecting plate and 1-2-2 parts of horizontal mounting plate.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
The invention provides a magnetic suspension type friction resistance measuring device, which comprises a floating plane component 1 and a support component used for supporting the plane component 1, wherein the support component is connected with an electromagnetic suspension control system, as shown in figures 1-7.
The floating plane component 1 comprises a floating panel 1-1, two opposite sides of the floating panel 1-1 are respectively provided with an installation platform 1-2 with an L-shaped cross section, the installation platform 1-2 comprises a vertical connecting plate 1-2-1 and a horizontal installation plate 1-2-2, the vertical connecting plate 1-2-1 is connected with the floating panel 1-1, and the upper surface of the horizontal installation plate 1-2-2 is provided with a steel plate 6 with a concave cross section; the floating panel 1-1 is located above the rack assembly.
The bracket component comprises an inverted T-shaped base 11, a lower fixing plate 5 is arranged at the top of the base 11, an upper fixing plate 12 is arranged above the lower fixing plate 5, and the lower fixing plate 5 and the upper fixing plate 12 are connected through a plurality of bolts;
the electromagnetic suspension control system comprises four electromagnetic suspension control units 10, each electromagnetic suspension control unit 10 comprises an operational amplifier 13, the output end of the operational amplifier 13 is connected with an electromagnetic coil 2, the positive and negative power ends of the operational amplifier 13 are connected with a direct current power supply 14, the electromagnetic coil 2 is also connected with the direct current power supply 14, and the negative electrode of the operational amplifier 13 is grounded; one input end of the operational amplifier 13 is sequentially connected with a PAC chip 15, a singlechip 16 and an eddy current displacement sensor 4; operational amplifierThe other input terminals of the amplifiers 13 are respectively connected with resistors R1And a resistance R2Resistance R1And also to the output of the operational amplifier 13; resistance R2One end is grounded;
the electromagnetic suspension control system also comprises four U-shaped magnetic cores 3 uniformly arranged between the lower fixing plate 5 and the upper fixing plate 12, each U-shaped magnetic core 3 is wound with one electromagnetic coil 2, and one U-shaped magnetic core 3 and one electromagnetic coil 2 form an electromagnet; every two electromagnets are arranged above the steel plate 6, and the end parts of the two ends of each U-shaped magnetic core 3 are arranged above the two bosses of the steel plate 6; the top end part of the electromagnetic coil 2 passes through the upper fixing plate 12; the four eddy current displacement sensors 4 are uniformly arranged on the upper fixing plate 12; a pull pressure sensor 7 is also mounted on the upper fixing plate 12. The DC power supply 14 has a voltage of 24-48V and a power of 250-500W.
The magnetic core 3 is made of silicon steel sheets, the coil is 3000-6000 circles, and the diameter of the enameled wire is 0.7 mm.
The measuring range of the eddy current displacement sensor 4 is 12.5mm, and the linearity error is less than or equal to +/-1%.
The pull pressure sensor 7 is an S-shaped pull pressure sensor, the measuring range is 1N, and the response frequency is 1 kHz.
The floating panel 1-1 is a square plane, is made of stainless steel (or other non-magnetic materials), and has a width of 500-2000 mm and a thickness of 8 mm.
The single chip microcomputer 16 adopts an STM32 chip set as a control core and has the capabilities of multi-path A/D and D/A acquisition, display and communication.
The lower fixing plate 5 and the upper fixing plate 12 are made of aluminum alloy, and the bolts are made of aluminum alloy.
As shown in fig. 8, the distance between eddy current displacement sensor 4 and the lower surface of floating panel 1-1 in the stationary state is 0. As shown in fig. 7, taking a set of electromagnetic levitation control units 10 as an example, the eddy current displacement sensor 4 feeds back a displacement signal to the single chip microcomputer 16 in real time, the single chip microcomputer 16 feeds back the displacement signal and generates a PWM signal, the PWM signal is transmitted to the PAC chip 15, the PAC chip 15 converts the PWM signal into an analog signal and transmits the analog signal to the non-inverting input terminal of the operational amplifier 13, the positive and negative power terminals of the operational amplifier 13 are connected to separate terminalsThe output end of the operational amplifier 13 independently supplies power to the electromagnetic coil 2 to generate electromagnetic force, and R in the amplifying circuit21K Ω, and a power supply voltage VmThen, then
The four groups of electromagnetic suspension control units 10 operate simultaneously to ensure that the vertical heights of the four corners of the floating plane assembly 1 are stabilized at a fixed value, and finally the floating panel 1-1 is kept horizontally suspended at a fixed height, and in addition, the U-shaped magnetic core 3 structure can generate a centripetal effect to limit the transverse movement of the floating plane assembly 1, so that the floating plane assembly 1 can only freely move along the flow direction.
When the airflow passes through the upper surface of the floating panel 1-1, because the floating panel 1-1 is supported by electromagnetic force, the floating panel 1-1 can be subjected to frictional resistance 9 generated by an incoming flow 8 to the floating panel 1-1 in the incoming flow direction, the floating plane assembly 1 can move in the incoming flow direction and act on the pull-pressure sensor 7 under the action of the frictional resistance, so that the frictional force of the incoming flow to the floating panel 1-1 can be completely transmitted to the pull-pressure sensor 7, and the pull-pressure sensor 7 finally transmits pressure data to a computer to obtain real frictional resistance data. The experimental device has the following advantages: firstly, a novel floating type force measuring balance supporting mode is provided, the interference of a supporting device to a floating plane is reduced, the measuring precision is improved, and the reproduction difficulty of an experiment is reduced; and secondly, the mechanical connection is not formed, the electric power is triggered, and the response speed is high. Thirdly, the device is insensitive to environmental factors such as humidity, temperature and the like and has high reliability. Fourthly, simple structure, low maintenance cost and long service life.
Claims (7)
1. Magnetic suspension type frictional resistance measuring device, its characterized in that is including floating plane subassembly (1) and the bracket component that is used for supporting plane subassembly (1), and the bracket component is connected with electromagnetic suspension control system.
2. The magnetic suspension type friction resistance measuring device according to claim 1, wherein the floating plane assembly (1) comprises a floating panel (1-1), two opposite sides of the floating panel (1-1) are respectively provided with an installation table (1-2) with an L-shaped cross section, the installation table (1-2) comprises a vertical connecting plate (1-2-1) and a horizontal installation plate (1-2-2), the vertical connecting plate (1-2-1) is connected with the floating panel (1-1), and the upper surface of the horizontal installation plate (1-2-2) is provided with a steel plate (6) with a concave cross section; the floating panel (1-1) is located above the bracket assembly.
3. The magnetic suspension type friction resistance measuring device according to claim 2, wherein the bracket assembly comprises an inverted T-shaped base (11), a lower fixing plate (5) is mounted on the top of the base (11), an upper fixing plate (12) is arranged above the lower fixing plate (5), and the lower fixing plate (5) and the upper fixing plate (12) are connected through a plurality of bolts;
the electromagnetic suspension control system comprises four electromagnetic suspension control units (10), each electromagnetic suspension control unit (10) comprises an operational amplifier (13), the output end of each operational amplifier (13) is connected with an electromagnetic coil (2), the positive and negative power ends of each operational amplifier (13) are connected with a direct current power supply (14), each electromagnetic coil (2) is also connected with the direct current power supply (14), and the negative electrode of each operational amplifier (13) is grounded; one input end of the operational amplifier (13) is sequentially connected with a PAC chip (15), a singlechip (16) and an eddy current displacement sensor (4); the other input ends of the operational amplifiers (13) are respectively connected with a resistor R1And a resistance R2Resistance R1And is also connected with the output end of the operational amplifier (13); resistance R2One end is grounded;
the electromagnetic suspension control system also comprises four U-shaped magnetic cores (3) uniformly arranged between the lower fixing plate (5) and the upper fixing plate (12), each U-shaped magnetic core (3) is wound with one electromagnetic coil (2), and one U-shaped magnetic core (3) and one electromagnetic coil (2) form one electromagnet; every two electromagnets are arranged above the steel plate (6), and the end parts of the two ends of each U-shaped magnetic core (3) are arranged above the two bosses of the steel plate (6); the top end part of the electromagnetic coil (2) penetrates through the upper fixing plate (12); the four eddy current displacement sensors (4) are uniformly arranged on the upper fixing plate (12); the upper fixing plate (12) is also provided with a pulling pressure sensor (7).
4. The magnetic levitation type frictional resistance measuring device as claimed in claim 3, wherein the DC power supply (14) has a voltage of 24-48V and a power of 250-500W.
5. The magnetic suspension type friction resistance measuring device according to claim 3, wherein the magnetic core (3) is made of silicon steel sheets, the number of the coils is 3000-6000, and the diameter of the enameled wire is 0.7 mm.
6. The magnetic levitation type frictional resistance measuring device according to claim 3, wherein the range of the eddy current displacement sensor (4) is 12.5mm, and the linearity error is ± 1% or less.
7. The magnetic levitation type frictional resistance measuring device according to claim 3, wherein the tension/pressure sensor (7) is an S-shaped tension/pressure sensor with a span of 1N and a response frequency of 1 kHz.
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| CN202111516511.5A CN114397050B (en) | 2021-12-10 | 2021-12-10 | Magnetic suspension type friction resistance measuring device |
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| CN202111516511.5A CN114397050B (en) | 2021-12-10 | 2021-12-10 | Magnetic suspension type friction resistance measuring device |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116296231A (en) * | 2023-01-09 | 2023-06-23 | 哈尔滨工业大学（深圳） | Air floatation balance for measuring wall friction of high-speed non-zero pressure gradient turbulence boundary layer |
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2021
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116296231A (en) * | 2023-01-09 | 2023-06-23 | 哈尔滨工业大学（深圳） | Air floatation balance for measuring wall friction of high-speed non-zero pressure gradient turbulence boundary layer |
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