CN114397227B - Polymer turbulence drag reduction evaluation device and method under variable magnetic field effect - Google Patents
Polymer turbulence drag reduction evaluation device and method under variable magnetic field effect Download PDFInfo
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Abstract
The invention relates to the field of complex turbulence control, and discloses a polymer turbulence drag reduction evaluation device and method under the action of a variable magnetic field. The device consists of a disc test system, a torque test system, a polymer structure observation system, an electromagnetic control system, a test liquid injection and discharge system, a temperature control system and other auxiliary systems. The polymer test solution is loaded with an induction magnetic field with controllable strength and direction through an excitation circuit, torque resistance generated when a disc rotates in the polymer solution is tested, and meanwhile, a polymer molecular structure is imaged by utilizing a polymer structure observation system, so that turbulent drag reduction, mechanical degradation performance evaluation and molecular behavior evaluation of the polymer under the action of magnetic fields of polymer solutions with different magnetic field strengths, different types and different concentrations under the conditions of different shearing rates, different temperatures and different shearing times are realized.
Description
Technical Field
The invention relates to the field of complex turbulence control, in particular to a design and drag reduction evaluation method of a polymer turbulence drag reduction testing device under the action of a variable magnetic field.
Background
Turbulence is a complex flow physical phenomenon with multi-scale irregularities, and because turbulence disturbance causes a great deal of energy dissipation in the flow process of the fluid, how to effectively reduce the turbulence energy dissipation has become one of the focuses of worldwide attention. Along with the continuous and intensive research of turbulent drag reduction technology by expert scholars of various countries, various drag reduction technologies are proposed and widely applied to various industrial fields, and various turbulent drag reduction effect evaluation devices and modes are also sequentially proposed. The polymer turbulence drag reduction technology has the advantages of low cost, convenience in operation, no influence on the quality of conveyed products and the like, and gradually takes the dominant role in the field of turbulence drag reduction.
The polymer drag reduction technology is to add very small amount of viscoelastic high molecular polymer into pipe flow to prevent turbulent vortex from developing, expanding and breaking, so as to realize turbulent drag reduction. The existing polymer turbulence drag reduction mechanism is mainly explained based on two aspects of polymer viscosity drag reduction and elastic drag reduction respectively. Viscous drag reduction is believed to reduce the turbulent dissipation rate by the energy cascade being truncated at a slightly larger turbulent vortex scale due to the polymer itself increasing the viscosity of the fluid, resulting in drag reduction; elastic drag reduction is considered that polymer molecular chains are stretched in a turbulent flow field, and polymer molecules absorb small-scale turbulent vortex energy and store the small-scale turbulent vortex energy in the stretched molecules in an elastic energy mode, so that turbulent kinetic energy is reduced, and drag reduction is caused.
Experiments have shown that during the polymer priming process to the turbulent flow field, drag reduction rates decrease over time from DR o to a minimum drag reduction rate DR min and then to a maximum drag reduction rate DR max, and that there is an increase in drag before the maximum drag reduction rate DR max is reached. Based on the elastic theory of polymer drag reduction, the time before the maximum drag reduction rate DR max is called polymer development time, in the first stage of the development time, the increase of flow resistance is related to the instantaneous increase of local elongational viscosity after polymer stretching and the arrangement orientation of molecular chains after polymer stretching, the instantaneous increase of local elongational viscosity and the dislocation orientation of the molecular chains of the polymer lead to the increase of flow resistance, and at the moment, the polymer stretching drag reduction is insufficient to offset the increase degree of flow resistance, namely the drag reduction rate is shown to be negative; in the second stage of development time, the drag reduction effect caused by the stretching action of the polymer is larger than the influence caused by the increase of the local stretching viscosity of the polymer, namely the drag reduction rate is positive, the drag reduction rate DR is increased along with the increase of time, and finally the maximum drag reduction rate DR max is reached. Macroscopic polymer drag reduction is shown in the stage that the drag reduction rate DR is more than or equal to 0, but the actual polymer drag reduction is carried out in the whole experimental process, so that the development time of the polymer is shortened, and the drag reduction rate DR reaches DR max in the fastest time, so that the polymer drag reduction technology is a key break for promoting the forward development of the polymer drag reduction technology.
Secondly, the high molecular polymer is a long linear chain macromolecule, and is extremely easy to degrade and damage due to shearing action from turbulence pulsation, elbows, valves, centrifugal pumps and the like in the pipeline flowing process. The orientation of the polymer molecular chains in the flowing process is random, so that the shear degradation damage is inferred to have certain randomness in a certain sense, and when the molecular chain orientation is perpendicular to the flowing direction, the molecular chain is subjected to larger shearing force, so that the analysis of the internal mechanism and rule of the polymer molecular degradation is particularly important for improving the shear resistance of the polymer molecules.
The existing research results show that the acting force among the fluid molecules can be destroyed by the magnetization effect generated by the magnetic field, the aggregation state among the molecules is changed, and the orientation of the molecular chain of the polymer macromolecules in the magnetic field is closely related to the direction of magnetic force lines after the polymer macromolecules in the magnetic field are fully magnetized. In combination with the existing polymer turbulence drag reduction theory and the research conclusion that the magnetic field has on the action of polymer macromolecules, the magnetic fields with different intensities and directions can change the flow orientation, the stretching degree and the compression modulus of polymer molecular chains so as to influence the drag reduction effect of the polymer, so that in order to explore the turbulent drag reduction and shearing degradation mechanism of the polymer molecules, the invention of a polymer turbulence drag reduction evaluation device under the action of a variable magnetic field is needed to be invented, and the device has important significance for the polymer turbulence drag reduction action mechanism, the degradation rule and the technical breakthrough of engineering application in complex turbulence control.
Disclosure of Invention
The invention aims to provide a polymer turbulence drag reduction evaluation device under the action of a variable magnetic field, so that the drag reduction efficiency evaluation of a polymer drag reducer under the action of the magnetic field is realized, and the drag reduction mechanism of the polymer and the degradation rule thereof are further revealed.
The invention relates to a polymer turbulence drag reduction evaluation device under the action of a magnetic field, which is shown in a figure 1 and comprises the following seven systems:
A disk testing system;
Torque testing system
A polymer structure observation system;
An electromagnetic control system;
Testing a liquid injection and discharge system;
a temperature control system;
other auxiliary systems.
The disc testing system comprises a rotary disc (1), a fluid testing inner sleeve (2) and a fluid testing domain infiltrating outer sleeve (3), as shown in figure 2. The diameter of the rotary disc (1) is 150mm, the middle thickness is 2mm, the edge thickness is 1mm, the upper surface is a conical surface, the lower surface is a plane, the rotary disc (1) is fixed on the rotating shaft (10), the upper surface and the lower surface of the disc are 9mm away from the upper surface and the lower surface of the fluid testing inner sleeve, and the edge of the disc is 5mm away from the side surface of the inner sleeve. The fluid test inner sleeve comprises an upper round cover plate and a lower round cover plate, the diameters of which are 160mm, and cylindrical side surfaces, the diameters of which are 160mm and the heights of which are 20mm, the upper and lower cover plates and the side surfaces are made of transparent PC plastic with the thickness of 2mm, a first liquid inlet (5) with the diameter of 4mm is formed in the position, which is 40mm away from the edge, of the right side of the upper cover plate, a liquid outlet (6) with the diameter of 4mm is formed in the position, which is the center of the circle, of the lower cover plate, and meanwhile, the upper cover plate is fixed on a stainless steel shell (7) of a rotating shaft (10), and the lower cover plate is adhered with the cylindrical side surfaces into a whole and is fixed with the upper cover plate through screws (4). The fluid testing area soaks outer sleeve (3) and comprises upper and lower circular apron and diameter 180mm, the high cylinder side that is 50mm of diameter all are 180mm, and lower surface and side are made by transparent PC plastics of thickness 3mm, and upper cover plate left and right sides is located to open second inlet (8) of diameter 4mm apart from edge 50mm, fixes upper cover plate on stainless steel shell (7) of pivot (10) to guarantee upper cover plate second inlet (8) and inner skleeve upper surface first inlet (5) are on same perpendicular line. The lower surface and the cylindrical side surface are adhered into a whole, the position of the cylindrical side surface with the height of 30mm is fixed on the upper surface of the outer sleeve in a groove type connection mode, namely, the side surface of the outer sleeve is 20mm higher than the upper surface of the outer sleeve, so that the fluid testing inner sleeve (2) and the infiltrating outer sleeve (3) are ensured to be completely filled with testing fluid.
The torque test system consists of a torque sensor (9), a rotating shaft (10), a first elastic coupler (11), a second elastic coupler (12), a motor (13) and a torque test control system (14), as shown in fig. 1. The torque sensor (9) is of an MCK-H101C type, the torque testing range is 0-5Nm, the maximum measuring error is +0.05Nm, the torque sensor (9) is fixed on a supporting rod (39) through a mounting supporting platform (37), the lower end of the torque sensor (9) is fixedly connected with a testing disc rotating shaft (10) in a concentric mode through a first elastic coupler (11), the upper end of the torque sensor (9) is fixedly connected with the motor rotating shaft (10) in a concentric mode through a second elastic coupler (12), and the first elastic coupler (11) and the second elastic coupler (12) are elastic couplers for reducing influences caused by vibration.
The polymer structure imaging observation system comprises a femtosecond laser emitter (15), a scanner (16), a microscope (17), a CCD sensor (18) and a computer (19) with an imaging system, wherein the femtosecond laser emitter (15) emits laser, the laser is focused on a testing fluid in a cylinder testing area sequentially through the scanner (16) and the microscope (17), fluorescent imaging is achieved on a polymer internal structure in the testing fluid, an optical signal of fluorescent imaging is transmitted to the CCD sensor (18) by the microscope (17) so that the optical signal is converted into an electric signal, and the computer (19) with the imaging system converts the received electric signal into a microscopic image of the polymer high molecular internal structure in the testing fluid. Before the experiment, a certain amount of fluorescent probe should be added to the test fluid. Wherein, the microscope (17) and the rotating shaft (10) are fixed on the same plane, so that the microscope (17) and the soaking outer sleeve (3) are kept vertical.
The electromagnetic control system comprises a direct current power supply (20), a voltage stabilizer (21), a resistor box (22), a switch (23), an ammeter (24) and an induction coil (25), as shown in fig. 3. The induction coil is made by uniformly winding copper wires on a steel cylindrical surface (26) with the diameter of 182mm, the height of 35mm and the thickness of 4mm, the number of turns of the wires is 400, four stainless steel hooks (27) are welded on the top of the steel cylindrical surface (26), the induction coil can be hung on a fluid testing area to infiltrate an outer sleeve (3), and the internal magnetic field of the induction coil (25) directly acts on the testing fluid area. The direct current power supply (20) selects a linear direct current power supply with input alternating current voltage of 220V and output voltage of 0-100V, and the power supply has an automatic protection function and can ensure the safe operation of a circuit. The resistor box (22) is a ZX25a direct current resistor box, and the resistance value of the resistor box is controllable within the range of 0.01-11.111 k omega. The ammeter (24) is a DC5A precision 0.5-level single-phase direct current meter, and the measuring range is 0-15A. The direct-current power supply (20), the voltage stabilizer (21), the resistor box (22), the switch (23), the ammeter (24) and the induction coil (25) are connected in series to form an excitation closed loop, and the intensity of the induction magnetic field is indirectly controlled through control voltage and resistance.
The test liquid injection and discharge system consists of an injection pipeline with the diameter of 3mm and a model 2PB8008 advection pump (28). When the test fluid is injected, an injection pipeline passes through the first liquid inlet (5) and the second liquid inlet (8), the advection pump (28) is started, the test fluid is firstly filled with the sleeve (2) in the test fluid field and then filled with the impregnating outer sleeve (3), and the liquid level of the test fluid reaches the 40mm scale of the impregnating outer sleeve, so that the test fluid field is ensured to be completely filled with the test fluid; when the test fluid is discharged, the soaking outer sleeve (3) is rotated to open the groove-shaped connection, the soaking outer sleeve (3) is removed, and the test fluid in the test inner sleeve is discharged from the liquid outlet (6) on the lower surface.
The temperature monitoring and controlling system comprises a water bath temperature control system and a temperature monitoring system. The water bath temperature control device consists of a water bath tank (32), a super constant-temperature water bath (33) and a water bath circulating pipe (34); the temperature monitoring system consists of a first temperature sensor (29), a second temperature sensor (30) and a paperless recorder (31). The first temperature sensor probe (29) penetrates through the fluid testing area through the fluid inlet and infiltrates the outer sleeve into the testing fluid area, when an experiment is started, the first temperature sensor probe is fixed on the upper cover plate of the infiltrating outer sleeve (3), and after the experiment is finished, the first temperature sensor probe is removed to facilitate the next experiment liquid inlet; and the probe of the second temperature sensor (30) is placed in a water bath tank (32) to monitor the water bath temperature in real time. The paperless recorder (31) has a temperature dual-channel display function, the first temperature sensor (29) and the second temperature sensor (30) are connected into the paperless recorder (31) at the same time, dual-channel temperature data monitoring is achieved, the paperless recorder has a data recording function, and external storage equipment can be connected to copy data.
The auxiliary system includes a signal transmission system, a power system, and a structural support system. The signal transmission system includes a test torque output signal, a test fluid temperature, and a polymer structure imaging output signal; the power system provides auxiliary power for power equipment by depending on 220V power supply voltage of a laboratory; the structural support system comprises an equipment base (35), a liftable table (36), a support platform (37), a support rod (39) and a flexible rubber pad (38).
Drawings
The purpose of the attached drawings is as follows: in order to more clearly illustrate the embodiments and technical solutions of the present invention, the drawings that are required for the embodiments will be simply labeled and described below.
FIG. 1 is a schematic diagram of a polymer turbulence drag reduction testing device under the action of a variable magnetic field
FIG. 2 is a schematic diagram of a disk test system
FIG. 3 is a schematic diagram of an electromagnetic control system
Detailed Description
In order that those skilled in the art will better understand the technical solutions in this specification, a clear and complete description of the technical solutions in one or more embodiments of this specification will be provided below with reference to the accompanying drawings in one or more embodiments of this specification, and it is apparent that the described embodiments are only some embodiments of the specification, not all embodiments. All other embodiments, which may be made by one or more embodiments of the disclosure without undue effort by one of ordinary skill in the art, are intended to be within the scope of the embodiments of the disclosure.
Embodiment 1: variable magnetic field effect test on drag reduction efficiency of polymer solution
The polymer turbulence drag reduction evaluation device under the action of the variable magnetic field can be used for evaluating the influence of the magnetic field on the turbulence drag reduction efficiency of the polymer solution.
Before testing, polymer solutions of different concentrations were first prepared and left to stand for one week to completely dissolve or disperse the polymer in the solvent. When the test is started, pouring the polymer solution into a container, starting a advection pump (28) to inject the polymer solution into the test inner sleeve (2), continuously injecting the test liquid after the solution is filled in the test inner sleeve (2), and enabling the liquid level to exceed the scale mark of the infiltrating outer sleeve (3) by more than 40mm, so that the test inner sleeve (2) is completely immersed in the test liquid, and simultaneously, preventing air from entering a test area; the method comprises the steps of connecting a resistor box (22) in an excitation circuit to a maximum resistance value, opening a direct current power supply (20), closing a switch (23), adjusting the connection resistance value of the resistor box (22), and observing the reading of an ammeter; the super constant temperature water bath (33) is opened, the reading of the 1 and 2 channels of the paperless recorder (31) is observed, and as the induction coil (25) is arranged in the constant temperature water bath (32), the temperature in the constant temperature water bath (32) is higher than the control temperature of the super constant temperature water bath (33) due to the heating of the electrified coil during working, the temperature of the super constant temperature water bath (33) is required to be regulated according to the reading of the 1 and 2 channels of the paperless recorder (31), so that the temperature of the test liquid is accurately controlled; opening a polymer turbulence drag reduction efficiency test program at the PC end, and setting parameters such as fluid rheological property, magnetic field strength, experimental temperature, shear rate range, shear rate change rate and the like; after the parameter setting is finished, confirming whether the temperature, the voltage and the current readings in the exciting circuit are consistent with the set values, starting a test program after the reading number is stable, starting rotary shearing of the rotary disc (1), and formally starting a test experiment; after the test is finished, the PC end turbulence drag reduction test program records and displays the shear rate gamma (·), the shear stress tau, the solution viscosity eta, the rotation speed n, the torsion resistance M, the friction coefficient f and the Reynolds number Re, and meanwhile, the magnetic field strength H is calculated according to the ammeter reading, and the calculation expression is as follows:
Wherein H is the magnetic field intensity, A/m;
N is the number of turns of the coil, n=400;
I is exciting current, A;
le is the effective magnetic path length, m.
The effect of magnetic field on turbulent drag reduction of polymer solution affects the computational expression:
Wherein K is the influence constant of the magnetic field on the drag reduction efficiency of the polymer solution; (K >0 exhibits positive acceleration, K <0 exhibits negative acceleration, K=0 exhibits no effect of the magnetic field on the drag reduction efficiency of the polymer turbulence.)
Τ, τ 0 are the shear stresses of the polymer solutions under the same test conditions with and without the application of a magnetic field, respectively.
In the embodiment, the current of the induction coil (25) can be regulated by changing the connection resistance value of a resistance changing box (22) in the exciting circuit, so that the magnetic field is indirectly controlled; meanwhile, the current direction can be changed by changing the positive and negative binding posts of the direct current power supply (20), so that the magnetic field direction can be changed, and the size and the direction of the magnetic field can be controlled.
Embodiment 2: test of influence of variable magnetic field on polymer turbulence drag reduction degradation rate
The polymer turbulence drag reduction evaluation device under the action of the variable magnetic field can be used for testing the mechanical degradation rate of the polymer turbulence drag reduction, and evaluating the mechanical degradation resistance of the polymer under the action of the magnetic field in the turbulence drag reduction process.
The polymer turbulence drag reduction mechanical degradation rate test is carried out by adopting a constant magnetic field and a constant shear rate. The experimental operation steps are the same as the testing steps in the embodiment 1, and the difference is that a polymer turbulence drag reduction testing program is opened at the PC end, the shear rate range and the shear rate change rate in the embodiment 1 are changed into constant shear rate, meanwhile, the continuous shear time is set, the other parameter setting modes are kept consistent, and the test experiment can be started after the parameter setting is completed; after the test is completed, the PC end turbulence drag reduction test program records and displays the shear rate gamma (·), the shear stress tau, the solution viscosity eta, the rotation speed n, the torsion resistance M, the friction coefficient f, the Reynolds number Re and the test time t.
The polymer turbulence drag reduction testing device under the action of the variable magnetic field can be used for testing polymer solutions with different magnetic field intensities, different types and different concentrations, and the turbulence drag reduction efficiency DR deg under the actions of different shearing rates, different temperatures and different shearing times is used for further evaluating the polymer turbulence drag reduction mechanical degradation rate under the action of the magnetic field, and the calculation expression is as follows:
wherein DR deg (t), DR (t) is the turbulent drag reduction efficiency of polymer solution with or without magnetic field under the same test conditions.
Embodiment 3: molecular behavior observation of polymer turbulence drag reduction under variable magnetic field
The polymer turbulence drag reduction testing device under the action of the variable magnetic field can be used for observing the molecular behaviors of the polymer, so that the analysis and research on the molecular behaviors of the polymer under the conditions of different flow fields and different magnetic field intensities are realized. The prior researches show that the influence of the magnetic field on the static flow field and the dynamic flow field is different, and the magnetic field is mainly characterized in that in the static polymer fluid, the magnetic field changes the molecular arrangement mode of the polymer to mainly overcome the viscous resistance of the fluid, and when the magnetic torque is larger than the intermolecular environmental resistance after the magnetic field is fully magnetized, the polymer molecules are regularly arranged parallel to magnetic force lines under the action of the magnetic field; in contrast, polymer molecules are subjected to larger flow shear stress in a dynamic flow field, the intermolecular environmental resistance is increased, and the magnetic field promotes more difficult regular arrangement of the polymer molecules. Therefore, the flow field state should be fully considered in the polymer molecular behavior test in the polymer turbulence drag reduction process under the action of the magnetic field, the viscous resistance of the polymer solution is represented by adopting the temperature, and the flow condition of the polymer in the turbulence is represented by the Reynolds number.
The polymer molecular behavior test mode in the polymer turbulence drag reduction process under the action of a magnetic field is the same as that of the embodiments 1 and 2, and the difference is that a proper amount of fluorescent probes are added into the test fluid before the experiment, a femtosecond laser emitter (15), a scanner (16), a microscope (17), a CCD sensor (18) and a computer (19) with an imaging system are required to be started in the formal experiment, the femtosecond laser emitter (15) emits laser, and the laser sequentially passes through the scanner (16) and the microscope (17) to focus the laser on the test fluid in a cylinder test area, so that fluorescent imaging is realized on the internal structure of the polymer in the test fluid, the microscope (17) transmits optical signals of fluorescent imaging to the CCD sensor (18) to convert optical signals into electric signals, and the computer (19) with the imaging system converts the received electric signals into microscopic images of the internal structure of the polymer in the test fluid. By observing microscopic images of the high polymer in the flow field under the action of different magnetic fields, the action influence of the magnetic fields on the polymer molecules in turbulent flow is analyzed.
The polymer turbulence drag reduction evaluation device based on the variable magnetic field can realize the influence test of the magnetic field on the drag reduction efficiency of the polymer solution, the influence test of the magnetic field on the drag reduction degradation rate of the polymer turbulence and the observation and evaluation of the polymer molecular behaviors in the polymer turbulence drag reduction process under the action of the magnetic field.
Claims (7)
1. The method for evaluating the polymer turbulence drag reduction performance under the condition of a variable magnetic field is based on a polymer turbulence drag reduction evaluation device under the action of the variable magnetic field, and is characterized by being capable of realizing the evaluation of the influence of the variable magnetic field on the drag reduction efficiency of a polymer solution, the evaluation of the influence of the variable magnetic field on the drag reduction degradation rate of the polymer turbulence and the evaluation of the influence of polymer molecular behaviors in the polymer turbulence drag reduction process under the action of the variable magnetic field, and comprises the following steps:
1) The method comprises the steps of evaluating the influence of a variable magnetic field on the drag reduction efficiency of a polymer solution, forming an induced magnetic field with controllable magnetic field intensity and direction by an excitation circuit, directly loading the induced magnetic field in a test fluid field, respectively testing shear stress tau of polymer solutions with different magnetic field intensities, directions and different concentrations and types under the same conditions by a disc test system during test, and calculating turbulent drag reduction efficiency values of the polymer solutions with different concentrations and types under the action of the magnetic fields with different intensities and directions, so as to evaluate the influence of the different magnetic fields on the turbulent drag reduction efficiency of the polymer solutions with different concentrations and types;
2) During testing, the turbulent drag reduction mechanical degradation rate of the polymer turbulence under the action of the magnetic field is evaluated by the turbulent drag reduction efficiency of the polymer solution with different types and different concentrations under different shearing rates, different temperatures and different shearing times of the magnetic field of the disk testing system under different intensities;
3) The method is characterized in that in the polymer turbulence drag reduction process under the action of a variable magnetic field, the influence of polymer molecular behaviors is evaluated, microscopic images of high polymer in a flow field under the action of different magnetic fields are observed through a polymer structure observation system, and therefore the molecular behaviors of polymer turbulence drag reduction under different magnetic field intensities are evaluated:
The polymer turbulence drag reduction evaluation device under the action of the variable magnetic field consists of a disc test system, a torque test system, a polymer structure observation system, an electromagnetic control system, a test liquid injection and discharge system, a temperature control system and other auxiliary systems; the disc test system is used for rotating shear test solution and comprises a rotating disc (1), a fluid test inner sleeve (2) and a fluid test field infiltration outer sleeve (3), wherein the fluid test inner sleeve (2) is composed of an upper round cover plate and a lower round cover plate which are both 160mm in diameter and a cylindrical side surface which is 160mm in diameter and 22mm in height, the upper round cover plate and the lower round cover plate are both made of PC plastics with the thickness of 2mm, the fluid test field infiltration outer sleeve (3) is composed of an upper round cover plate and a lower round cover plate which are both 180mm in diameter and a cylindrical side surface which is both 180mm in diameter and 50mm in height, the lower surface and the side surface are both made of PC plastics with the thickness of 3mm, and an induction coil (25) is hung on the cylindrical side surface of the fluid test field infiltration outer sleeve (3); the torque testing system is used for testing the torque resistance of the rotating disc; the polymer structure observation system is fixed right above the testing fluid domain and is used for testing the polymer molecular behavior information; the electromagnetic control system is formed by connecting a linear direct current power supply (20) with the voltage of 0-100V, a voltage stabilizer (21), a ZX25a type direct current resistor box (22), a switch (23), an ammeter (24) and an induction coil (25) in series; the induction coil is made of copper wires uniformly wound on a steel cylindrical surface (26) with the diameter of 182mm, the height of 35mm and the thickness of 4mm, the number of turns of the wires is 400, four stainless steel hooks (27) are welded at the top of the steel cylindrical surface (26), the coil can be directly hung on an outer soaking sleeve, and the coil is directly loaded outside the disc test system to provide an induction magnetic field for a fluid test area; the test liquid injection and discharge system is directly connected with the disc test system and is used for injecting and discharging test liquid; the temperature control system is used for controlling and monitoring the temperature of the test fluid; the auxiliary system includes a transmission system, a power system, and a structural support system.
2. The method for evaluating the resistance reduction of the polymer turbulence under the action of a variable magnetic field according to claim 1, wherein the diameter of the rotating disc (1) is 150mm, the middle thickness is 2mm, the edge thickness is 1mm, the upper surface is a conical surface, the lower surface is a plane, the rotating disc (1) is fixed on a rotating shaft (10), the upper surface and the lower surface of the disc are 9mm away from the upper surface and the lower surface of an inner sleeve for fluid testing, and the edge of the disc is 5mm away from the side surface of the inner sleeve; a first liquid inlet (5) with the diameter of 4mm is formed in the position 40mm away from the edge on the right side of an upper cover plate of the fluid testing inner sleeve (2), a liquid outlet (6) with the diameter of 4mm is formed in the center of a lower cover plate, meanwhile, the upper cover plate is fixed on a stainless steel shell (7) of a rotating shaft (10), and the lower cover plate is adhered with the side face into a whole and is fixed with the upper cover plate through a screw (4); the fluid testing area infiltrates second liquid inlets (8) with the diameter of 4mm are formed in the positions, 50mm away from the edge, of the left side and the right side of an upper cover plate of the outer sleeve (3), the upper cover plate is fixed on a stainless steel shell (7) of a rotating shaft (10), the second liquid inlets (8) and the first liquid inlets (5) on the upper surface of the inner sleeve are guaranteed to be on the same straight line, the lower surface and the side surfaces are adhered into a whole, the position with the height of 30mm on the side surfaces is fixed on the upper surface of the outer sleeve in a groove type connection mode, and namely the side surfaces of the outer sleeve are 20mm higher than the upper surface of the outer sleeve.
3. The method for evaluating the resistance reduction of the polymer turbulence under the action of the variable magnetic field according to claim 1, wherein the torque testing system comprises an MCK-H101C type torque sensor (9), a rotating shaft (10), a first elastic coupler (11), a second elastic coupler (12), a motor (13) and a torque testing control system (14); the torque sensor (9) is fixed on the supporting rod (39) through the mounting supporting platform (37), the lower end of the torque sensor (9) is fixedly connected with the rotating shaft (10) through the first elastic coupling (11), and the upper end of the torque sensor (9) is fixedly connected with the rotating shaft (10) through the second elastic coupling (12).
4. The method for drag reduction evaluation of polymer turbulence under the action of a variable magnetic field according to claim 1, wherein the polymer structure imaging observation system comprises a fluorescent probe, a femtosecond laser transmitter (15), a scanner (16), a microscope (17), a CCD sensor (18) and a computer (19) with an imaging system.
5. The method for evaluating the resistance reduction of the polymer turbulence under the action of the variable magnetic field according to claim 1, wherein the test liquid injection and discharge system consists of an injection pipeline with the diameter of 3mm, a model 2PB8008 advection pump (28), a first liquid inlet (5), a second liquid inlet (8) and a liquid outlet (6).
6. The method for evaluating turbulent drag reduction of polymer under the action of a variable magnetic field according to claim 1, wherein the water bath temperature control device consists of a water bath tank (32), a super constant temperature water bath (33) and a water bath circulating pipe (34); the temperature monitoring system consists of a first temperature sensor (29), a second temperature sensor (30) and a dual-channel paperless recorder (31); the first temperature sensor (29) is arranged on the test inner sleeve, and the second temperature sensor (30) is arranged on the test outer sleeve.
7. The method for drag reduction evaluation of polymer turbulence under the action of a variable magnetic field according to claim 1, wherein the auxiliary system comprises a signal transmission system, an electric power system and a structural support system; the power system provides auxiliary power for power equipment by depending on 220V power supply voltage of a laboratory; the structural support system comprises an equipment base (35), a liftable table (36), a support platform (37), a support rod (39) and a flexible rubber pad (38).
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