Demonstration experiment device for internal friction effect in gas fluid mechanics

Abstract

The invention provides a demonstration experiment device for an internal friction effect in gas fluid mechanics, and belongs to the technical field of teaching demonstration devices. The problem that a traditional teaching aid is single in function, dispersed in data and insufficient in visualization, so that the experiment effect is abstract is solved. Comprising a main body shell, the main body shell is hermetically connected with a vacuum cover, the vacuum cover is filled with fluorescent powder, and the vacuum cover is connected with an air extractor through an air valve; the middle of the main body shell is an area communicated with the interior of the vacuum cover, the periphery of the main body shell is a sealed shell, the middle of the main body shell is provided with an impeller rotating speed adjusting mechanism, the top of the sealed shell of the main body shell is provided with a display screen, and the sealed shell of the main body shell is internally provided with a high-speed brushless motor and a distance adjusting mechanism; by adjusting the air pressure, the rotating speed of the impeller and the distance, students can observe the conversion of gas flow from laminar flow to turbulent flow and the stagnation phenomenon of the impeller in a vacuum environment, and the linear relation between internal friction and gas density is verified.

Description

Technical Field

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

[0002] With the development of teaching, the teaching methods are becoming more and more diversified, and various experimental demonstration equipment for specific subjects are constantly emerging. In the teaching process of teachers, the use of specific teaching or demonstration equipment can help explain some basic concepts, while making the teaching process more vivid and interesting, improving the teaching quality, and helping students learn and understand more easily.

[0003] The internal friction of gas, also known as viscosity, is the resistance generated by the intermolecular interaction during gas flow, and is an important topic for understanding fluid viscosity, momentum transfer, and energy dissipation mechanisms. Traditional teaching demonstration devices mostly use single variable design experiments, such as adjusting only air pressure or speed, and lack multi-parameter coordinated control functions, which limits the experimental content and makes it difficult to fully demonstrate the complex mechanism of gas internal friction.

[0004] In the prior art, the traditional teaching demonstration device has the following technical problems: 1. Single function: Traditional devices are usually unable to synchronously adjust parameters such as air pressure and impeller spacing, which limits the diversity of experimental design.

[0005] 2. Lack of visualization methods: Most devices rely on theoretical derivation to assist teaching and lack dynamic flow field display functions. It is difficult for students to intuitively observe the experimental phenomena of internal friction in gases and the transition process between laminar flow and turbulent flow, and the teaching effect relies on abstract understanding.

[0006] 3. Data is scattered and fragmented: key parameters such as rotation speed and air pressure need to be measured by independent instruments. The data are scattered and difficult to correlate in real time, and a complete experimental closed loop cannot be formed, which affects students' systematic understanding of the friction mechanism of gas. Summary of the invention

[0007] In order to solve the problem that traditional teaching aids have single functions, scattered data, and insufficient visualization, resulting in abstract experimental effects, this application proposes a demonstration experimental device for the internal friction effect in gas fluid mechanics.

[0008] The technical solution adopted in the present application is: a demonstration experimental device for the internal friction effect in gas fluid mechanics, comprising a main body shell, a vacuum cover is sealedly connected to the main body shell, the vacuum cover is filled with fluorescent powder, and the vacuum cover is connected to a vacuum pump through an air valve; The middle of the main body shell is an area connected to the inside of the vacuum cover, and the surrounding of the main body shell is a sealed shell, wherein an impeller speed adjustment mechanism is installed in the middle of the main body shell, a display screen is installed on the top of the sealed shell of the main body shell, and a high-speed brushless motor and a spacing adjustment mechanism are installed inside the sealed shell of the main body shell; The impeller speed regulating mechanism comprises an upper impeller and a lower impeller, the upper impeller is connected to a bearing, the bearing is fixed on a support frame, and the lower impeller is connected to a high-speed brushless motor; The spacing adjustment mechanism includes a reduction motor, a driven gear and a rack. A driving gear meshing with the driven gear is installed on the output shaft of the reduction motor. The driven gear meshes with the rack. One end of the rack extending out of the sealing housing is fixedly connected to the support frame. An air pressure sensor for detecting the air pressure in the vacuum cover is installed in the area where the main body shell communicates with the vacuum cover; A Hall speed sensor for non-contact measurement of the upper impeller speed is installed on the support frame; A UV light strip is installed on the sealed housing located outside the lower impeller to excite the fluorescent powder and display the gas flow trajectory; The display screen is connected to the Hall speed sensor and the air pressure sensor through wires.

[0009] Furthermore, a speed regulator for adjusting the speed of the high-speed brushless motor and two spacing regulators for adjusting the forward and reverse rotation of the reduction motor are installed on the top of the sealed shell of the main shell. The speed regulator and the two spacing regulators are connected to the display screen through wires respectively.

[0010] Furthermore, the vacuum pump is used to adjust the air pressure in the vacuum hood, and the air pressure adjustment range is 1000Pa to normal pressure.

[0011] Furthermore, the high-speed brushless motor is connected to the lower impeller through magnetic coupling transmission, and the speed of the high-speed brushless motor is adjusted by a speed regulator, and the speed adjustment range is 0-2000rpm.

[0012] Furthermore, the speed regulator is provided with scales corresponding to different speeds.

[0013] Furthermore, a magnet is installed at the axis of the upper impeller, and the Hall speed sensor cooperates with the magnet to detect the speed of the upper impeller and transmit the data to the display screen in real time.

[0014] Furthermore, the vacuum cover is made of a transparent double-layer acrylic material.

[0015] Furthermore, an airtight seal is achieved between the vacuum cover and the main body shell through a rubber gasket.

[0016] Furthermore, the UV light strip adopts an ultraviolet light strip with a power of ≤5W, and a protective filter is installed on the outside of the UV light strip.

[0017] Furthermore, the spacing adjustment mechanism controls the forward and reverse rotation of the reduction motor through two spacing adjusters, drives the driven gear and rack transmission, realizes the vertical displacement control of the upper impeller, and thus dynamically adjusts the spacing between the upper and lower impellers. The adjustment range of the upper and lower impeller spacing is 5-50mm.

[0018] The beneficial effects of this application compared to the prior art are: 1. Multivariable collaborative control and precise measurement: The device of this application integrates the functions of air pressure regulation, impeller speed control and dynamic spacing adjustment, supporting complex experimental scene design; the magnetic coupling non-contact speed measurement eliminates the interference of mechanical friction and ensures that the data can accurately reflect the friction effect inside the gas; 2. Dynamic flow field visualization enhancement: safe ultra-light fluorescent powder is mixed into the vacuum cover, combined with UV light strip to stimulate the fluorescent trajectory, and the gas flow state is displayed in real time, intuitively presenting the transition process from laminar flow to turbulent flow; 3. Data integration and teaching closed loop: The rotation speed and air pressure data are displayed synchronously on the display screen, and the experimental report template is provided to guide students to record data and fit formulas (such as), forming a complete logical chain of "operation-observation-deduction". BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present application is further described below with reference to the accompanying drawings: Figure 1 A schematic diagram of the structure of a demonstration experimental device for the internal friction effect in gas fluid mechanics provided in an embodiment of the present application; Figure 2 A front view of the main structure of a demonstration experimental device for the internal friction effect in gas fluid mechanics provided in an embodiment of the present application; Figure 3 A top view of the main structure of a demonstration experimental device for the internal friction effect in gas fluid mechanics provided in an embodiment of the present application; Figure 4 A top view of the internal structure (excluding the vacuum cover) of the main structure part of a demonstration experimental device for the internal friction effect in gas fluid mechanics provided in an embodiment of the present application; Figure 5 for Figure 3 Sectional view of AA in the middle; In the figure: 1 is a vacuum pump, 2 is a main body shell, 3 is a rubber gasket, 4 is a UV light strip, 5 is a vacuum cover, 6 is an air valve, 7 is a connecting piece, 8 is a Hall speed sensor, 9 is a support frame, 10 is an upper impeller, 11 is a rack, 12 is a driven gear, 13 is a driving gear, 14 is a bearing, 16 is a high-speed brushless motor, 17 is an air pressure sensor, 18 is a lower impeller, 19 is a display screen, 20 is a speed regulator, and 21 is a spacing adjuster. DETAILED DESCRIPTION

[0020] like Figures 1 to 5 As shown, the present application provides a demonstration experimental device for the internal friction effect in gas fluid mechanics, which adopts multi-parameter collaborative control and dynamic visualization technology. The core of the device is to integrate air pressure regulation, impeller speed control, dynamic adjustment of spacing and real-time flow field display functions, which can fully demonstrate the physical mechanism of gas internal friction.

[0021] Specifically, the demonstration experimental device of the internal friction effect in gas fluid mechanics provided in the embodiment of the present application is composed of two parts, namely, a main structure part and an air pump 1, wherein the main structure part is mainly composed of a main shell 2 and a vacuum cover 5, which are sealed and connected by a rubber gasket 3, and when in use, the vacuum cover 5 can be filled with safe ultra-light fluorescent powder with a particle size of about 25 μm. In this embodiment, the vacuum cover 5 can be made of transparent double-layer acrylic.

[0022] An air valve 6 is installed on the top of the vacuum cover 5. The vacuum pump 1 is connected to the vacuum cover 5 through the air valve 6 for adjusting the internal air pressure. In this embodiment, the air pressure adjustment range is 1000 Pa to normal pressure.

[0023] The middle of the main shell 2 is an area connected to the inside of the vacuum cover 5, and the four sides of the main shell 2 are sealed shells, wherein an impeller speed adjustment mechanism is installed in the middle of the main shell 2, a display screen 19, a speed regulator 20 and two spacing adjusters 21 are installed on the top of the sealed shell of the main shell 2, and a high-speed brushless motor 16 and a spacing adjustment mechanism are installed inside the sealed shell of the main shell 2.

[0024] The impeller speed regulating mechanism includes an upper impeller 10 and a lower impeller 18. The upper impeller 10 is connected to the bearing 14 through a connecting piece 7, and the bearing 14 is fixed on the support frame 9. The lower impeller 18 is driven by a high-speed brushless motor 16, and the high-speed brushless motor 16 adjusts the speed through a speed regulator 20. The spacing regulating mechanism includes a reduction motor, a driven gear 12 and a rack 11, wherein a driving gear 13 meshing with the driven gear 12 is installed on the output shaft of the reduction motor, the driven gear 12 meshes with the rack 11, and the rack 11 extends out of the sealed housing. One end is fixedly connected to the support frame 9, and the rack 11 can move in the slide groove opened inside the sealing shell of the main shell 2, thereby driving the support frame 9 to move up and down, and then realizing the adjustment of the spacing between the upper impeller 10 and the lower impeller 18; the forward and reverse rotation of the reduction motor is realized by two spacing adjusters 21, and the reduction motor drives the driven gear 12 and the rack 11 to transmit by receiving the signal of the spacing adjuster 21, so as to realize the vertical displacement control of the upper impeller 10, thereby dynamically adjusting the spacing (5-50mm) between the upper impeller 10 and the lower impeller 18.

[0025] A Hall speed sensor 8 is installed on the support frame 9 for non-contact measurement of the speed of the upper impeller 10 (accuracy ±1rpm). A magnet is installed at the axis of the upper impeller 10, and the Hall speed sensor 8 can achieve real-time measurement of the speed of the upper impeller 10 by cooperating with the magnet. In this embodiment, a neodymium magnet can be used in conjunction with the Hall speed sensor 8 to achieve real-time measurement of the speed of the upper impeller 10.

[0026] A circle of UV light strip 4 is installed on the sealed shell outside the lower impeller 18 to excite the fluorescent powder to display the gas flow trajectory; in this embodiment, a UV light strip 4 with a wavelength of 365nm and a power of ≤5W is selected, and a protective filter is installed to avoid direct ultraviolet rays.

[0027] In this embodiment, the high-speed brushless motor 16 and the lower impeller 18 are connected through magnetic coupling transmission, and the speed is adjusted by the speed regulator 20 in the range of 0-2000rpm, and the speed regulator 20 is marked with a scale corresponding to the speed.

[0028] An air pressure sensor 17 may be installed in the communication area in the middle of the main housing 2 to monitor the air pressure inside the vacuum cover 5 in real time.

[0029] A touch controller is integrated on the display screen 19. The Hall speed sensor 8, the air pressure sensor 17, the speed regulator 20, and the spacing adjuster 21 are all connected to the display screen 19. The rotation speed of the upper impeller 10, the air pressure in the vacuum cover 5, and the spacing between the upper and lower impellers can be synchronously displayed (refresh rate ≥ 10Hz), and the display screen 19 also supports remote control of the wireless module.

[0030] Here’s how this application works: By adjusting the speed of the high-speed brushless motor 16, the lower impeller 18 is driven to rotate, which drives the gas flow and drives the upper impeller 10 to rotate. The fluorescent track is displayed as an orderly laminar flow through the UV light strip 4; the air pressure in the vacuum hood 5 is reduced by the vacuum pump 1, the gas density is reduced, the internal friction is weakened, the speed of the upper impeller 10 is significantly reduced, and the fluorescent track turns into turbulent turbulence. By adjusting the speed of the high-speed brushless motor 16 by the speed regulator 20, the law of the change of the gas internal friction effect with the speed can be intuitively observed. By changing the spacing between the upper and lower impellers by the spacing regulator 21, the change of the gas momentum transfer efficiency under different upper and lower impeller spacings can be observed. The above experimental data can be observed in real time through the display screen 19, and students can fit the quantitative relationship between the viscosity coefficient and the gas density and speed, forming a complete teaching closed loop of "operation-observation-derivation".

[0031] The following is a detailed description of the operation steps and data analysis methods of this application, combining the experimental process with theoretical derivation. By introducing formulas, it helps students transition from experimental phenomena to quantitative analysis and deepen their understanding of the internal friction mechanism of gases.

[0032] 1. Comparison experiment between normal pressure and vacuum 1. Experimental steps Normal pressure group: Start the high-speed brushless motor 16 to the set speed (such as 1000rpm), observe the scale on the display screen 19 and the speed regulator 20, and record the speed of the upper impeller 10 , the speed of the lower impeller 18 and air pressure .

[0033] Vacuum group: Start the vacuum pump 1 to reduce the air pressure in the vacuum cover 5 to the target value (such as 1000Pa), keep the speed of the high-speed brushless motor 16 unchanged, and record The speed of the impeller 10 decreases significantly (eg <10 rpm), and finally the upper impeller 10 only trembles slightly.

[0034] 2. Formula application and derivation The relationship between viscosity and density: Viscosity coefficient of internal friction of gas With gas density Approximately a linear relationship, that is: ; in is the proportionality constant.

[0035] By measuring the different air pressures , it can be deduced The law of change; Data calculation: using the ideal gas state equation ,in is the gas constant, is the temperature, and the pressure Convert to gas density .

[0036] 3. Draw conclusions Air pressure in a vacuum state The corresponding gas density is reduced Reduce viscosity The power transmission efficiency of the upper impeller 10 decreases, that is, the internal friction of the gas decreases.

[0037] 2. Impeller speed adjustment experiment 1. Experimental steps Fixed air pressure It is normal pressure (i.e. 101kPa), and the distance between the upper and lower impellers is 20mm.

[0038] The speed of the high-speed brushless motor 16 is set to 500 rpm, 1000 rpm, 1500 rpm, and 2000 rpm in sequence by the speed regulator 20, and the speed at each speed is recorded. .

[0039] 2. Formula application and derivation Newton's Law of Viscosity: Shear stress caused by internal friction of the gas (internal friction) With velocity gradient The following relations are satisfied: ; Where: represents the viscosity coefficient (unit: Pa·s), Indicates a small change in speed (in m / s). Indicates the small distance change perpendicular to the fluid flow direction (in m); in It can be estimated by the lower impeller speed and the upper and lower impeller spacing: ; Where: is the impeller radius, is the distance between upper and lower impellers.

[0040] In this experiment, the radii of the upper and lower impellers are set to be the same. .

[0041] 3. Draw conclusions As the speed of the high-speed brushless motor 16 increases from 500 rpm to 1000 rpm, 1500 rpm, and 2000 rpm, the The reason for this experimental phenomenon can be deduced from the above formula: as the speed of the high-speed brushless motor 16 increases, the speed gradient increases and the internal friction effect increases.

[0042] 3. Impeller spacing adjustment experiment 1. Experimental steps Fixed air pressure The pressure is normal (ie 101 kPa), and the rotation speed of the high-speed brushless motor 16 is 1000 rpm.

[0043] The distance between the upper and lower impellers is set by the distance adjuster 21 They are 10mm, 15mm, and 20mm respectively. data.

[0044] 2. Formula application and derivation The same formula as Newton's law of viscosity used in the above impeller speed regulation experiment. The experimental variable in this experiment is the distance between the upper and lower impellers. .

[0045] 3. Draw conclusions The distance between the upper and lower impellers When adjusted to 10mm, 15mm, and 20mm respectively, the corresponding The reason for this experimental phenomenon can be deduced by the formula: the distance between the upper and lower impellers As the velocity increases, the velocity gradient decreases and the internal friction effect decreases.

[0046] This application transforms a number of abstract theories into actionable experiments through magnetic coupling non-contact speed measurement, fluorescence tracing and multivariable collaborative control technology, significantly improving teaching effectiveness and students' practical cognitive ability.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, 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 gas fluid mechanics, characterized by: It comprises a main body shell (2), a vacuum cover (5) being sealedly connected to the main body shell (2), the vacuum cover (5) being filled with fluorescent powder, and the vacuum cover (5) being connected to the vacuum pump (1) via an air valve (6); The middle of the main housing (2) is an area connected to the inside of the vacuum cover (5), and the surrounding of the main housing (2) is a sealed housing, wherein an impeller speed adjustment mechanism is installed in the middle of the main housing (2), a display screen (19) is installed on the top of the sealed housing of the main housing (2), and a high-speed brushless motor (16) and a spacing adjustment mechanism are installed inside the sealed housing of the main housing (2); The impeller speed regulating mechanism comprises an upper impeller (10) and a lower impeller (18), the upper impeller (10) is connected to a bearing (14), the bearing (14) is fixed on a support frame (9), and the lower impeller (18) is connected to a high-speed brushless motor (16); The spacing adjustment mechanism comprises a reduction motor, a driven gear (12) and a rack (11); a driving gear (13) meshing with the driven gear (12) is mounted on the output shaft of the reduction motor; the driven gear (12) meshes with the rack (11); one end of the rack (11) extending out of the sealing housing is fixedly connected to the support frame (9); An air pressure sensor (17) for detecting the air pressure in the vacuum cover (5) is installed in the area where the main housing (2) communicates with the vacuum cover (5); A Hall speed sensor (8) for non-contact measurement of the speed of the upper impeller (10) is mounted on the support frame (9); A UV light strip (4) for exciting fluorescent powder to display the gas flow trajectory is installed on the sealed housing located outside the lower impeller (18); The display screen (19) is connected to the Hall speed sensor (8) and the air pressure sensor (17) respectively through wires.

2. The demonstration experimental device for the internal friction effect in gas fluid mechanics according to claim 1, characterized in that: A speed regulator (20) for adjusting the rotation speed of the high-speed brushless motor (16) and two spacing regulators (21) for adjusting the forward and reverse rotation of the reduction motor are also installed on the top of the sealed housing of the main housing (2). The speed regulator (20) and the two spacing regulators (21) are respectively connected to the display screen (19) through wires.

3. The demonstration experimental device for the internal friction effect in gas fluid mechanics according to claim 1, characterized in that: The vacuum pump (1) is used to adjust the air pressure in the vacuum cover (5), and the air pressure adjustment range is from 1000 Pa to normal pressure.

4. The demonstration experimental device for the internal friction effect in gas fluid mechanics according to claim 2, characterized in that: The high-speed brushless motor (16) is connected to the lower impeller (18) via magnetic coupling transmission, and the speed of the high-speed brushless motor (16) is adjusted via a speed regulator (20), with the speed adjustment range being 0-2000 rpm.

5. The demonstration experimental device for the internal friction effect in gas fluid mechanics according to claim 4, characterized in that: The speed regulator (20) is provided with scales corresponding to different rotation speeds.

6. The demonstration experimental device for the internal friction effect in gas fluid mechanics according to claim 1, characterized in that: A magnet is installed at the axis of the upper impeller (10), and the Hall speed sensor (8) cooperates with the magnet to detect the speed of the upper impeller (10) and transmit the data to the display screen (19) in real time.

7. The demonstration experimental device for the internal friction effect in gas fluid mechanics according to claim 1, characterized in that: The vacuum cover (5) is made of a transparent double-layer acrylic material.

8. The demonstration experimental device for the internal friction effect in gas fluid mechanics according to claim 1, characterized in that: An airtight seal is achieved between the vacuum cover (5) and the main body shell (2) via a rubber gasket (3).

9. The demonstration experimental device for the internal friction effect in gas fluid mechanics according to claim 1, characterized in that: The UV light strip (4) is an ultraviolet light strip with a power of ≤5W, and a protective filter is installed on the outside of the UV light strip (4).

10. The demonstration experimental device for the internal friction effect in gas fluid mechanics according to claim 2, characterized in that: The spacing adjustment mechanism controls the forward and reverse rotation of the reduction motor through two spacing adjusters (21), drives the driven gear (12) and the rack (11) to achieve vertical displacement control of the upper impeller (10), thereby dynamically adjusting the spacing between the upper impeller (10) and the lower impeller (18), and the upper and lower impeller spacing adjustment range is 5-50 mm.

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