A demonstration experimental device for the internal friction effect in liquid hydrodynamics

Abstract

The present application provides a demonstration experimental device for the internal friction effect in liquid fluid mechanics, belonging to the technical field of experimental demonstration devices; it solves the problem that the existing devices cannot accurately and quantitatively verify the internal friction force of liquids; it includes a main body frame, on which a support rod is fixed. On the support rod, a viscometer bracket and a container bracket are respectively connected through two fastening devices. The end of the viscometer bracket is fixedly connected with a viscometer, and a viscometer rotor is connected to the viscometer. The end of the container bracket is rotatably connected with a second container connector, and a second container is detachably connected to the second container connector; a turntable is arranged on the top of the main body frame, and a first container is placed on the turntable. An electric motor is also fixed inside the main body frame, and a laser velocimeter for measuring the rotation speed of the second container is fixed on the main body frame on one side of the turntable; the present application is applicable to the teaching, research and related experiments of fluid mechanics courses.

Description

Technical Field

[0001] This application relates to the technical field of teaching demonstration devices, and particularly to a demonstration experimental device for the internal friction effect in liquid fluid mechanics. Background Art

[0002] With the vigorous development of the education cause, teaching methods are increasingly showing a diversified trend. At the same time, teaching experimental demonstration devices for specific subject experiments are also emerging continuously. In the process of teachers carrying out teaching activities, using various teaching equipment or demonstration devices with simple structures can not only vividly explain some basic concepts in the classroom, but also make the teaching process more interesting, effectively improve the teaching quality, and enable students to learn and understand knowledge more easily.

[0003] The internal frictional force of a liquid, that is, the viscous force, is the resistance generated by the intermolecular interaction force during the liquid flow process. It is related to the flow characteristics of the liquid and is usually closely related to factors such as the viscosity of the liquid, the flow velocity, and the geometric shape of the flow space. In fluid mechanics, the study of internal frictional force is the basis for understanding fluid motion and its behavior. Therefore, its accurate measurement and quantitative analysis have important theoretical significance and practical value.

[0004] However, most traditional internal frictional force demonstration devices lack sufficient flexibility and adjustment functions. Many existing devices cannot adjust the viscosity, flow velocity of the liquid, or the geometric shape of the container, and cannot provide a diversified experimental environment. Therefore, researchers and students are often restricted by fixed conditions during the experiment and it is difficult to comprehensively and accurately explore various influencing factors of the internal frictional force in the liquid.

[0005] In addition, although some existing devices can demonstrate the basic laws of liquid flow, their teaching and research value is limited to a certain extent because they cannot perform accurate quantitative experimental verification. Accurately measuring and adjusting parameters such as viscosity, flow velocity, and container spacing are crucial for deeply understanding the internal frictional force of the liquid. Therefore, there is an urgent need for a new experimental device that can simultaneously adjust and measure these key factors for quantitative verification. Summary of the Invention

[0006] In order to solve the problem that the existing devices cannot perform accurate quantitative verification when demonstrating the internal frictional force of the liquid, this application proposes a demonstration experimental device for the internal friction effect in liquid fluid mechanics.

[0007] The technical solution adopted by this application is as follows: A demonstration experimental device for the internal friction effect in liquid fluid mechanics, including a main frame, a support rod is fixed on the main frame, a viscometer bracket and a container bracket are respectively connected to the support rod through two fastening devices, a viscometer is fixedly connected to the end of the viscometer bracket, a viscometer rotor is connected to the viscometer, a second container connector is rotatably connected to the end of the container bracket, and a second container is detachably connected to the second container connector;

[0008] A turntable is arranged on the top of the main frame, a first container is placed on the turntable, and a motor is also fixed inside the main frame, and the output shaft of the motor is key-connected to the turntable;

[0009] A laser velocimeter for measuring the rotational speed of the second container is fixed on the main frame on one side of the turntable;

[0010] A speed display screen and a speed regulator are also arranged on the top of the main frame, the laser velocimeter is connected to the speed display screen through a wire, and the speed regulator is connected to the controller of the motor through a wire.

[0011] Further, length-adjustable regulators are respectively arranged at the four corners of the bottom of the main frame, chassis are installed at the bottoms of the four regulators, and a level is also arranged on the top of the main frame.

[0012] Further, the top end of the second container connector is a shaft, a second angular contact ball bearing is connected to the shaft, the second angular contact ball bearing is fixed at the end of the container bracket, the lower end of the second container connector is provided with a thread, and a connecting screw hole matching the thread on the second container connector is fixed at the top of the second container.

[0013] Further, a bearing support frame is also fixed inside the main frame, a first angular contact ball bearing is fixed on the bearing support frame, a shaft sleeve matching the first angular contact ball bearing is arranged at the bottom of the turntable, and a keyway is also arranged at the center of the bottom of the turntable, and the output shaft of the motor is matched with the keyway at the bottom of the turntable through a key.

[0014] Further, a plurality of air holes are opened at the bottom of the second container.

[0015] Further, the fastening device includes an open socket sleeve sleeved on the support rod and a screw for fastening the open socket sleeve. When the open socket sleeve is not tightened, the fastening device can move and rotate on the support rod.

[0016] Further, the size of the second container is smaller than that of the first container, so that the second container can be placed inside the first container.

[0017] Further, both the first container and the second container are made of a transparent material resistant to chemical corrosion.

[0018] Further, a spiral marking line is provided on the second container.

[0019] Further, the governor is engraved with angular velocity scales.

[0020] The beneficial effects of the present application compared with the prior art are as follows: A demonstration experimental device for the internal friction effect in liquid fluid mechanics provided by the present application can accurately adjust the viscosity, flow rate, and container spacing of the liquid, and has high flexibility, capable of meeting the requirements of different experimental conditions. This device can effectively display the law of the change of liquid internal friction force with these variables, providing a more intuitive and accurate experimental platform for the teaching and research of liquid fluid mechanics. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The following further describes the present application with reference to the drawings:

[0022] Figure 1 It is a schematic structural diagram of a demonstration experimental device for the internal friction effect in liquid fluid mechanics (excluding the second container) provided by an embodiment of the present application;

[0023] Figure 2 It is a front view of the device provided by an embodiment of the present application when measuring the viscosity of the liquid;

[0024] Figure 3 It is Figure 2 a sectional view taken along A - A in

[0025] Figure 4 It is a front view of the device provided by an embodiment of the present application when measuring the internal friction force of the liquid;

[0026] Figure 5 It is Figure 4 a sectional view taken along B - B in

[0027] In the figure: 1 is the chassis, 2 is the regulator, 3 is the main body frame, 4 is the laser velocimeter, 5 is the viscometer, 6 is the support rod, 7 is the viscometer rotor, 8 is the first container, 9 is the first angular contact ball bearing, 10 is the turntable, 11 is the motor, 12 is the bearing support frame, 13 is the spirit level, 14 is the viscometer support, 15 is the speed display screen, 16 is the governor, 17 is the container support, 18 is the second angular contact ball bearing, 19 is the fastening device, 20 is the second container connecting piece, 21 is the second container. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] As Figures 1 to 5As shown in the figure, the present application provides a demonstration experimental device for the internal friction effect in liquid fluid mechanics, aiming to intuitively demonstrate the viscous properties of liquids and their internal friction effects, including a main frame 3. At the four corners of the bottom of the main frame 3, regulators 2 with controllable telescopic lengths are respectively arranged. The bottoms of the four regulators 2 are all installed with chassis 1, which is used to adapt to rough surfaces and ensure the horizontal stability of the device. A level 13 is also arranged at the top of the main frame 3. The regulators 2 can adjust the height and angle of the chassis 1 according to different experimental environments, and then the level 13 is used to check the horizontal state of the device. The settings of the regulators 2 and the level 13 can ensure that the device remains horizontal on rough or uneven surfaces, thereby avoiding experimental errors caused by instability.

[0029] A support rod 6 is fixed on the main frame 3. A viscometer bracket 14 and a container bracket 17 are respectively connected to the support rod 6 through two fastening devices 19. A viscometer 5 is fixed at the end of the viscometer bracket 14. A viscometer rotor 7 is connected to the viscometer 5. The introduction of the viscometer 5 and the viscometer rotor 7 can measure the viscosities of different liquids for the analysis of quantitative experiments. Moreover, the viscometer 5 and the viscometer rotor 7 are tightly connected and can measure the viscosity of liquids under different liquid conditions. By selecting different types of liquids, researchers can measure the frictional force of liquids during flow and correlate it with variables such as the viscosity and flow rate of liquids. This function can not only help demonstrate the importance of liquid viscosity but also provide more intuitive and specific experimental data support for students.

[0030] A second container connector 20 for connecting second containers 21 of different sizes is fixed at the end of the container bracket 17. The height of the viscometer bracket 14 and the container bracket 17 can be adjusted through the fastening device 19, and the viscometer bracket 14 and the container bracket 17 can be rotated to the side of the device when not in use through the fastening device 19.

[0031] A turntable 10 is also arranged at the top of the main frame 3. A first container 8 is placed on the turntable 10. A raised ring is arranged around the turntable 10. In actual use, the first container 8 is selected to match the diameter of the turntable 10, and the first container 8 is exactly stuck in the turntable 10 by the raised ring around the turntable 10 and will not move. A laser velocimeter 4 is fixed on the main frame 3 on one side of the first container 8. A motor 11 and a bearing support frame 12 are installed inside the main frame 3. A first angular contact ball bearing 9 is fixed on the bearing support frame 12. A bushing that cooperates with the first angular contact ball bearing 9 is arranged at the bottom of the turntable 10. A keyway is also arranged at the center of the bottom of the turntable 10. The output shaft of the motor 11 is matched with the keyway at the bottom of the turntable 10 through a key. The turntable 10 is driven to rotate by the rotation of the motor 11, so that the first container 8 rotates.

[0032] At the top of the main frame 3, there are also a speed display screen 15 and a speed governor 16. Among them, the laser speed detector 4 is connected to the speed display screen 15 through a wire. The laser speed detector 4 is used to accurately measure the rotation speed of the second container 21 and display it in real time through the speed display screen 15. The high-precision characteristic of the laser speed detector 4 makes it possible to measure the change of the liquid flow state at different flow rates, which helps to demonstrate the rotation and flow characteristics of the liquid under different experimental conditions. In addition, the data provided by the laser speed detector 4 can be directly correlated with the internal friction force of the liquid, further verifying the relationship between the liquid viscosity and the flow rate.

[0033] The speed governor 16 is connected to the controller of the motor 11 through a wire. The motor 11 provides rotational power with adjustable angular velocity through the speed governor 16, thereby adjusting the speed of the liquid flow. And there are angular velocity scales engraved on the speed governor 16, which can conveniently set different flow rate values, facilitating the adjustment of the rotation speed of the first container 8 for quantitative experiments, so as to demonstrate the internal friction effect of the liquid at different angular velocities. The precise adjustment of the liquid flow rate is an important step in the experiment because the flow rate directly affects the magnitude of the internal friction force of the liquid.

[0034] The top end of the second container connecting piece 20 is a shaft, and a second angular contact ball bearing 18 is connected to the shaft. The second angular contact ball bearing 18 is fixed at the end of the container support 17. The lower end of the second container connecting piece 20 is provided with a thread, and a connecting screw hole matching the thread on the second container connecting piece 20 is fixed at the top of the second container 21. When in use, the second container 21 can be directly screwed onto the second container connecting piece 20. And the setting of the second container connecting piece 20 can facilitate the disassembly and replacement of the second container 21 with different bottom diameters to adjust the container spacing. Through this design, users can replace the second container 21 with different sizes according to experimental needs, thereby changing the container spacing, which directly affects the internal friction force when the liquid flows. The ability to adjust the container spacing makes the experiment more flexible and can accurately verify the law of the internal friction force changing with the size of the second container 21 under different experimental conditions.

[0035] The fastening device 19 includes an open socket piece sleeved on the support rod 6 and a screw for fastening the open socket piece. When the open socket piece is not tightened, the fastening device 19 can move and rotate on the support rod 6.

[0036] To ensure the repeatability and stability of the experimental conditions, both the first container 8 and the second container 21 are made of chemically corrosion-resistant transparent materials to adapt to a variety of liquid experimental environments and facilitate observation. This design not only helps to observe the internal friction effect generated during the liquid flow process but also facilitates the observation of the state and morphological changes of the liquid flow.

[0037] There are air holes provided inside the bottom of the second container 21, and several ventilation openings are provided at the top of the second container 21. This design can discharge the excess gas in the liquid during liquid addition, avoid the interference of bubbles on the liquid flow and experimental results, and ensure the stability of the liquid and pressure balance during the experiment. Moreover, there are spiral marking lines provided on the second container 21 for observing the rotation phenomenon.

[0038] Both the first container 8 and the second container 21 can adopt the shape of a measuring cup. In this embodiment, the first container 8 is a cylindrical measuring cup with a fully open top, and the second container 21 is a cylindrical measuring cup, and the bottom diameter of the second container 21 is smaller than the bottom diameter of the first container 8.

[0039] The following will describe in detail the process of quantitatively verifying the internal friction through the device of this application.

[0040] 1. Experiment preparation and viscosity measurement

[0041] First, level the device through the regulator 2 and the level 13. Before conducting the internal friction experiment, it is first necessary to measure the viscosity of the liquid through the viscometer 5. The specific process is as follows:

[0042] According to the required experimental conditions, add the experimental liquid into the first container 8. The viscometer 5 contacts the liquid through the viscometer rotor 7, and the viscometer 5 and the viscometer rotor 7 are fixed on the support rod 6 of the device through the fastening device 19. At this time, the liquid is in full contact with the viscometer rotor 7. When ensuring that the position of the viscometer rotor 7 is appropriate, measure the viscosity of the liquid through the viscometer 5.

[0043] After the viscosity measurement is completed, use the fastening device 19 to adjust the positions of the viscometer 5 and the viscometer rotor 7 to one side to facilitate the subsequent experimental operations.

[0044] 2. Installation of the second container 21 and internal friction experiment

[0045] After completing the viscosity measurement, the experimenter first adjusts the second container connecting member 20 to directly above the first container 8 through the fastening device 19, then installs the second container 21 and ensures its stable connection with the second container connecting member 20. Then adjust the container spacing between the second container 21 and the first container 8. Finally, tighten the fastening device 19 to ensure that the container bracket 17 will not shake or move during the experiment.

[0046] Next, start the motor 11 and precisely control the rotation speed of the motor 11 through the speed regulator 16. Real-time monitor the rotation speed of the second container 21 through the laser velocimeter 4 and transmit the data to the speed display screen 15 for the experimenter to observe and record the change in the rotation speed of the second container 21 during the experiment.

[0047] By observing and recording the flow state of the liquid at different rotational speeds, the experimenters can analyze the change in the rotational speed of the second container 21, i.e., the internal friction force, of the liquid under different viscosities, flow rates, and container spacings.

[0048] Then, replace the second container 21 with different bottom diameters to adjust the container spacing between the second container 21 and the first container 8. Repeat the above experimental process to conduct experiments on the internal friction force of the liquid under different container spacings.

[0049] 3. Data Acquisition and Analysis

[0050] During the experiment, the laser velocimeter 4 continuously measures the rotational speed of the second container 21 and displays the rotational speed data in real time through the speed display screen 15. By adjusting the rotational speed of the motor 11 and the viscosity of the liquid and the container spacing, the experimenters can obtain the rotational speed data of the second container 21 under different conditions.

[0051] In the experiment, viscous shear flow is used, and when the internal friction force of the liquid is reflected by adjusting the rotational speed of the second container 21, a formula related to the viscosity, flow rate, and container spacing of the liquid can be derived.

[0052] Considering the shear flow caused by the rotation of the second container 21, the internal friction force mainly comes from the shear stress of the liquid, and this shear stress is directly related to the viscosity and velocity gradient (i.e., the rate of change of velocity) of the liquid. This embodiment gives a formula for the internal friction force related to the rotational speed of the second container 21 and the container spacing.

[0053] Assume that the rotational speed of the second container 21 generates a velocity gradient between liquid layers. In viscous shear flow, the following relationship exists between the shear stress of the liquid and the velocity gradient:

[0054] ;

[0055] In the formula: is the shear stress (internal friction force) of the liquid, with the unit of Pa, is the viscosity of the liquid, with the unit of Pa·s, is the velocity gradient, with the unit of s -1 , representing the rate of change of the liquid flow velocity in the radial direction, is the small change in velocity, with the unit of m / s, is the small change in the distance perpendicular to the fluid flow direction, with the unit of m.

[0056] For the second container 21 rotating in this device, the velocity gradient can be expressed as:

[0057] ;

[0058] In the formula: is the angular velocity of the second container, in rad / s is the radius of the second container, in m is the distance between containers, in m

[0059] The relationship between the change in the internal friction force of the liquid and the viscosity, rotational speed, and distance between containers of the liquid can be quantitatively calculated through the aforementioned formula and is intuitively reflected in the rotational speed of the second container 21 measured by the laser velocimeter 4. Based on these data, the experimenter can verify the relationship between the internal friction force of the liquid and viscosity, flow rate, and distance between containers and further analyze the hydrodynamic characteristics under different experimental conditions.

[0060] By integrating multiple experimental functions, this application can effectively demonstrate the viscous characteristics of liquids under different flow conditions, meet the requirements for quantitative experiments and dynamic demonstrations in liquid hydrodynamics teaching and research, and has high application value.

[0061] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A demonstration experimental device for the internal friction effect in liquid hydrodynamics, characterized in that: It includes a main frame (3), a support rod (6) is fixed on the main frame (3), a viscometer bracket (14) and a container bracket (17) are respectively connected to the support rod (6) through two fastening devices (19), a viscometer (5) is fixedly connected to the end of the viscometer bracket (14), a viscometer rotor (7) is connected to the viscometer (5), a second container connector (20) for connecting second containers (21) of different sizes is rotatably connected to the end of the container bracket (17), and the second container (21) is detachably connected to the second container connector (20); A turntable (10) is arranged on the top of the main frame (3), a first container (8) is placed on the turntable (10), and a motor (11) is also fixed inside the main frame (3), and the output shaft of the motor (11) is key-connected to the turntable (10); The size of the second container (21) is smaller than that of the first container (8) so that the second container (21) can be placed inside the first container (8); A laser velocimeter (4) for measuring the rotation speed of the second container (21) is fixed on the main frame (3) on one side of the turntable (10); A speed display screen (15) and a speed regulator (16) are also arranged on the top of the main frame (3), the laser velocimeter (4) is connected to the speed display screen (15) through a wire, and the speed regulator (16) is connected to the controller of the motor (11) through a wire.

2. The demonstration experimental device for the internal friction effect in liquid hydrodynamics according to claim 1, characterized in that: Adjusters (2) with adjustable lengths are respectively arranged at the four corners of the bottom of the main frame (3), chassis (1) are installed at the bottoms of the four adjusters (2), and a spirit level (13) is also arranged on the top of the main frame (3).

3. A demonstration experimental device for the internal friction effect in liquid hydrodynamics according to claim 1 or 2, characterized in that: The top end of the second container connector (20) is a shaft, a second angular contact ball bearing (18) is connected to the shaft, the second angular contact ball bearing (18) is fixed at the end of the container bracket (17), the lower end of the second container connector (20) is provided with a thread, and a connecting screw hole matching the thread on the second container connector (20) is fixed at the top of the second container (21).

4. A demonstration experimental device for internal friction effect in liquid hydrodynamics according to claim 1 or 2, characterized in that: A bearing support frame (12) is also fixed inside the main frame (3), a first angular contact ball bearing (9) is fixed on the bearing support frame (12), a shaft sleeve matching the first angular contact ball bearing (9) is arranged at the bottom of the turntable (10), a keyway is also arranged at the center of the bottom of the turntable (10), and the output shaft of the motor (11) is matched with the keyway at the bottom of the turntable (10) through a key.

5. A demonstration experimental device for the internal friction effect in liquid hydrodynamics according to claim 1, characterized in that: A plurality of air holes are opened at the bottom of the second container (21).

6. A demonstration experimental device for the internal friction effect in liquid hydrodynamics according to claim 1, characterized in that: The fastening device (19) includes an open socket sleeve sleeved on the support rod (6) and a screw for fastening the open socket sleeve. When the open socket sleeve is not tightened, the fastening device (19) can move and rotate on the support rod (6).

7. A demonstration experimental device for the internal friction effect in liquid hydrodynamics according to claim 1, characterized in that: Both the first container (8) and the second container (21) are made of a transparent material resistant to chemical corrosion.

8. A demonstration experimental device for the internal friction effect in liquid hydrodynamics according to claim 5, characterized in that: A spiral marking line is provided on the second container (21).

9. The demonstration experimental device for the internal friction effect in liquid hydrodynamics according to claim 1, wherein: The speed regulator (16) is engraved with angular velocity scales.

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