CN114397050B - Magnetic suspension type friction resistance measuring device - Google Patents
Magnetic suspension type friction resistance measuring device Download PDFInfo
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- CN114397050B CN114397050B CN202111516511.5A CN202111516511A CN114397050B CN 114397050 B CN114397050 B CN 114397050B CN 202111516511 A CN202111516511 A CN 202111516511A CN 114397050 B CN114397050 B CN 114397050B
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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 component and a bracket component for supporting the plane component, wherein the bracket component is connected with an electromagnetic suspension control system. The magnetic suspension type friction resistance measuring device can reduce the interference of the supporting device on the floating surface to the greatest 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 the transportation means such as an airplane, an automobile, a ship and the like in operation is reduced, so that 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 of searching drag reduction technology, and the accurate acquisition of frictional resistance generated by the surface of a measured object in the experiments is important to 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 smaller, the precision requirement is relatively higher (10) -1 N/m 2 The level), the value measured by the existing experimental measurement equipment has great uncertainty, and the difficulty of the recurrence of experimental results in the scientific research process is increased, so how to accurately measure the friction resistance of the surface of the measured object becomes a difficult problem in the flow control research process, and how to measure the friction resistance of the fluid under the condition of applying different flow control methods is a problem which needs to be solved currently.
Existing fluid resistance measuring methods are generally classified into indirect measuring methods and direct measuring methods. The indirect measurement method can be mainly classified into measurement based on a velocity profile and measurement based on heat convection heat exchange according to a measurement principle. The method based on the speed profile measurement is provided on the basis of a classical turbulence boundary layer layering model, and the turbulence friction resistance is calculated according to the relation between the speed profile and the resistance, but the calculation of the resistance has certain subjectivity because part of coefficients used for calculation are different in different flow conditions and the limitation of a logarithmic zone is not very definite; the heat convection heat transfer technology is mainly represented by a thermal film measurement technology, and the change of the temperature of the thermal film sensor is in linear relation with the conducted heat, so that the wall friction resistance and the electric signal are related, and the heat convection heat transfer technology has high frequency response, but when certain active flow control (such as plasma flow control) is applied, the temperature of fluid is increased by the injected heat of the active flow control, so that the measured data is seriously influenced. The direct measurement method mainly utilizes a floating force measuring balance to measure, and as the name suggests, the floating force measuring balance uses a certain method to suspend the surface to be measured and acts on a high-precision tension pressure sensor to reduce the interference of a measuring device on the floating surface as much as possible, and compared with the indirect measurement, the direct measurement can obtain more visual experimental data. The initial floating force balance is supported by a mechanical structure, and then a balance supported by high-pressure air and liquid medium appears, but the interference of a supporting device on measurement accuracy cannot be completely eliminated no matter whether the balance is of a high-pressure air, liquid medium or mechanical structure.
The magnetic suspension technology is used as a non-contact supporting mode, and a new direction is pointed out for eliminating the interference of a supporting structure. The magnetic suspension technology is a technology for achieving suspension by overcoming gravity by utilizing magnetic force, and can be applied to the suspended magnet, and the following three types are adopted: the electromagnet, the superconducting magnet and the permanent magnet are controlled by current to control the intensity of a magnetic field, and compared with the permanent magnet and the superconducting magnet, the electromagnet can realize active magnetic force control and realize stable support of the floating element.
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 a floating plane and improve the measuring precision.
The technical scheme adopted by the invention is that the magnetic suspension type friction resistance measuring device comprises a floating plane component and a bracket component for supporting the plane component, wherein the bracket 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 a mounting table with an L-shaped cross section, each mounting table comprises a vertical connecting plate and a horizontal mounting plate, the vertical connecting plates are connected with the floating panel, and the upper surfaces of the horizontal mounting plates are provided with steel plates with concave cross sections; the floating panel is positioned 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 is connected with the upper fixing plate 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 each operational amplifier is connected with an electromagnetic coil, the positive power supply and the negative power supply of each operational amplifier are connected with a direct current power supply, the electromagnetic coils are also connected with the direct current power supplies, and the negative electrode of each 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 R 1 Resistor R 2 Resistance R 1 The output end of the operational amplifier is connected with the output end of the operational amplifier; resistor R 2 One end of the device 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 the U-shaped magnetic cores and the electromagnetic coil form an electromagnet; four electromagnets are arranged above the steel plate in pairs, and the two end parts of each U-shaped magnetic core are arranged above two bosses of the steel plate; the top end of the electromagnetic coil passes through the upper fixing plate; the four eddy current displacement sensors are uniformly arranged on the upper fixing plate; and a tension and pressure sensor is also arranged on the upper fixing plate. The DC power supply has a voltage of 24-48V and a power of 250-500W.
The magnetic core is made of silicon steel sheet, the coil is 3000-6000 circles, and the diameter of the enameled wire is 0.7mm.
The range of the eddy current displacement sensor is 12.5mm, and the linear 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 1kHz.
The beneficial effects of the invention are as follows:
(1) The device provided by the invention provides a novel floating plane supporting mode, the measurement interference of the supporting device on the floating plane is reduced by utilizing a magnetic suspension technology, and the measurement accuracy of friction resistance and the repeatability of experiments are improved.
(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 provided by the invention can be suitable for measuring friction resistance in different wind speed ranges, and has strong applicability.
Drawings
FIG. 1 is a schematic 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 view of a B-B cross section of the magnetic levitation frictional resistance measuring device of the present invention;
FIG. 5 is a view showing the working state of the magnetic levitation frictional resistance measuring device according to the present invention in section A-A of an actual flow field;
FIG. 6 is an enlarged view at J of FIG. 5;
FIG. 7 is a schematic diagram showing the connection relationship of an electromagnetic levitation control unit in the magnetic levitation frictional resistance measuring apparatus according to the present invention.
Fig. 8 is a front view showing a stationary state of the magnetic levitation type frictional resistance measuring apparatus of the present invention.
In the figure, a floating plane assembly, a magnetic coil, a magnetic core, a current vortex displacement sensor, a lower fixing plate, a steel plate, a pulling pressure sensor, a true incoming flow, a friction resistance, an electromagnetic suspension controller, a base, a upper fixing plate, an operational amplifier, a direct current power supply, a 15 PAC chip and a single chip microcomputer, wherein the floating plane assembly, the magnetic coil, the magnetic core, the current vortex displacement sensor, the lower fixing plate, the steel plate, the pulling pressure sensor, the true incoming flow, the friction resistance and the friction resistance are respectively arranged in sequence, the electromagnetic suspension controller, the base and the upper fixing plate are respectively arranged in sequence, and the operational amplifier, the operational amplifier and the direct current power supply are respectively arranged in sequence, the direct current power supply and the single chip microcomputer are respectively arranged in sequence, and the magnetic core is arranged in sequence, the sequence, and the magnetic core is composed of the floating plane assembly, the magnetic core, the electromagnetic coil, the magnetic core, the current vortex displacement sensor and the current displacement sensor and the magnetic core, the lower fixing plate and the magnetic core, the current and the magnetic core and;
1-1 parts 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 invention will be described in detail below with reference to the drawings and the detailed description.
The invention provides a magnetic suspension type friction resistance measuring device, which is shown in figures 1-7, and comprises a floating plane component 1 and a bracket component for supporting the plane component 1, wherein the bracket component is connected with an electromagnetic suspension control system.
The floating plane assembly 1 comprises a floating panel 1-1, wherein 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 bracket assembly.
The bracket assembly 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 is connected with the upper fixing plate 12 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 power supply and the negative power supply of each operational amplifier 13 are connected with a direct current power supply 14, the electromagnetic coils 2 are also connected with the direct current power supplies 14, and the negative electrode of each operational amplifier 13 is grounded; one input end of the operational amplifier 13 is sequentially connected with the PAC chip 15, the singlechip 16 and the eddy current displacement sensor 4; the other input ends of the operational amplifier 13 are respectively connected with a resistor R 1 Resistor R 2 Resistance R 1 The output end of the operational amplifier 13 is also connected with the output end of the output end; resistor R 2 One end of the device is grounded;
the electromagnetic suspension control system also comprises four U-shaped magnetic cores 3 which are uniformly arranged between the lower fixing plate 5 and the upper fixing plate 12, wherein an electromagnetic coil 2 is wound on each U-shaped magnetic core 3, and one electromagnet is formed by one U-shaped magnetic core 3 and one electromagnetic coil 2; four electromagnets are arranged above the steel plate 6 in pairs, and the end parts of the two ends of each U-shaped magnetic core 3 are arranged above two bosses of the steel plate 6; the top end 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; the upper fixing plate 12 is also provided with a tension and pressure sensor 7. 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 sheet, the coil is 3000-6000 circles, and the diameter of the enameled wire is 0.7mm.
The range of the eddy current displacement sensor 4 is 12.5mm, and the linear 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 1kHz.
The floating panel 1-1 is a square plane, and is made of stainless steel (or other non-magnetic materials), and has a width of 500-2000 mm and a thickness of 8mm.
The singlechip 16 adopts an STM32 chip set as a control core and has the multi-path A/D and D/A acquisition, display and communication capabilities.
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 the eddy current displacement sensor 4 and the lower surface of the floating panel 1-1 in the stationary state is 0. As shown in fig. 7, taking a group of electromagnetic suspension control units 10 as an example, the eddy current displacement sensor 4 feeds back displacement signals to the singlechip 16 in real time, the singlechip 16 feeds back the PWM signals to the PAC chip 15, the PAC chip 15 converts the PWM signals into analog signals and transmits the analog signals to the in-phase input end of the operational amplifier 13, the positive and negative power supplies of the operational amplifier 13 are connected with separate dc power supplies 14, the output end of the operational amplifier 13 supplies power to the electromagnetic coil 2 alone to generate electromagnetic force, and R in the amplifying circuit 2 Let the supply voltage be V =1kΩ m ThenThe four groups of electromagnetic suspension control units 10 operate simultaneously to ensure that the vertical heights of four corners of the floating plane assembly 1 are stable 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 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 air flow 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 the incoming flow 8 on the floating panel 1-1 in the incoming flow direction, and the floating plane component 1 can move along the 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 on 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, so that real frictional resistance data can be obtained. The experimental device has the following advantages: firstly, a novel floating force balance supporting mode is provided, the interference of a supporting device on a floating plane is reduced, the measuring precision is improved, and the recurrence difficulty of experiments is reduced; and secondly, no mechanical connection exists, the electric power is triggered, and the response speed is high. And thirdly, the device is insensitive to environmental factors such as humidity, temperature and the like, and the reliability is high. Fourth, simple structure, low maintenance cost and long service life.
Claims (5)
1. The magnetic suspension type friction resistance measuring device is characterized by comprising a floating plane component (1) and a bracket component for supporting the plane component (1), wherein the bracket component is connected with an electromagnetic suspension control system;
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 positioned above the bracket component;
the bracket assembly 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) is connected with the upper fixing plate (12) 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 power supply and the negative power supply of each operational amplifier (13) are connected with a direct current power supply (14), and the electromagnetic coils (2) are also connected with the direct current power supplies(14) 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); the other input end of the operational amplifier (13) is respectively connected with a resistor R 1 Resistor R 2 Resistance R 1 The output end of the operational amplifier (13) is also connected with the output end of the operational amplifier; resistor R 2 One end of the device is grounded;
the electromagnetic suspension control system further comprises four U-shaped magnetic cores (3) which are uniformly arranged between the lower fixing plate (5) and the upper fixing plate (12), each U-shaped magnetic core (3) is wound with an electromagnetic coil (2), and one U-shaped magnetic core (3) and one electromagnetic coil (2) form an electromagnet; four electromagnets are arranged above the steel plate (6) in pairs, and the end parts of the two ends of each U-shaped magnetic core (3) are arranged above two bosses of the steel plate (6); the top end 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); the upper fixing plate (12) is also provided with a tension and pressure sensor (7).
2. The magnetic levitation type frictional resistance measurement device according to claim 1, wherein the direct current power supply (14) has a voltage of 24 to 48V and a power of 250 to 500W.
3. The magnetic suspension type friction resistance measuring device according to claim 1, wherein the magnetic core (3) is made of silicon steel sheet, the coil is 3000-6000 circles, and the diameter of the enameled wire is 0.7mm.
4. The magnetic levitation type frictional resistance measurement device according to claim 1, wherein the range of the eddy current displacement sensor (4) is 12.5mm, and the linear error is less than or equal to + -1%.
5. The magnetic levitation type frictional resistance measurement device according to claim 1, wherein the pull pressure sensor (7) is an S-type pull pressure sensor, the measuring range is 1N, and the response frequency is 1kHz.
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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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| CN116296231B (en) * | 2023-01-09 | 2024-03-19 | 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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