Demonstration instrument for showing dynamic prototype of fixed-wing aircraft

Abstract

The utility model discloses a demonstration instrument for showing the dynamic prototype of a fixed wing aircraft, which comprises a demonstration platform and a control device, a vertical frame is arranged on the demonstration platform, a wing model capable of freely ascending and descending is arranged on the vertical frame, a frequency conversion fan is arranged on one side of the demonstration platform, and an air pipe is arranged at an air outlet of the frequency conversion fan. An air outlet of the air pipe faces the direction of the wing model, a concave mirror is arranged on the demonstration platform on the rear side of the wing model, a schlieren imaging device is arranged on the demonstration platform at the position twice the focal length of the center of the concave mirror, a displayer connected with the schlieren imaging device is arranged on the demonstration platform, and the control device is communicated with the frequency conversion draught fan. According to the utility model, the fluid change phenomenon which cannot be seen by naked eyes when airflow passes through the wing-shaped structure can be visually displayed, and the generated acting force has the advantages of scientificity, objective authenticity, visual demonstration effect and the like when applied to the airplane model.

Description

Technical Field

[0001] The utility model relates to the technical field of popular science teaching of aviation knowledge, in particular to a demonstrator showing the power prototype of a fixed-wing aircraft. Background Art

[0002] The most important scientific and technological principles that allow airplanes to soar into the sky are thrust and lift. The existence of these two forces enables airplanes to take off and land and fly. The specific principles are as follows: the cross-section of an airplane wing is generally rounded at the front end, sharp at the rear end, with an arched upper surface and a relatively flat lower surface. When equal mass air passes through the upper and lower surfaces of the wing at the same time, the special configuration of the wing makes the airflow have different flow rates above and below the wing, and the pressure generated is also different. The air passing through the upper surface of the wing has a large flow rate and a small pressure, while the air passing through the lower surface of the wing has a small flow rate and a large pressure. In this way, the airflow will generate an upward combined force on the aircraft, which is lift. The lift allows the aircraft to leave the ground, and combined with the thrust, the aircraft flies forward, thus enabling the aircraft to fly in the air.

[0003] However, the understanding of the source of force, the existence of force, and the principles of aerodynamic pressure difference is often in an abstract concept, which is difficult to understand. In order to concretize these abstract concepts, some teaching aids and exhibits that demonstrate the lift of the wing will be used accordingly in the teaching of schools and the display of science and technology museums. The wing section model is used to illustrate that the airflow velocity difference forms pressure, and then lifts the model up. However, these teaching aids and exhibits often have the following problems during the demonstration: First, due to the colorless airflow and the fast flow rate, people still cannot intuitively observe the airflow changes with the naked eye, and the demonstration effect is still unsatisfactory; second, the teaching aids and exhibits are mostly fixed static demonstration forms, which cannot well demonstrate the running trajectory of the wing model, and people's experience and participation are not high, and the dynamic relationship between the force and the wing model cannot be well reflected, and there is a problem of poor demonstration effect. Therefore, it is an objective need to develop a demonstrator that can intuitively display airflow, can perform dynamic demonstration, and has a good demonstration effect to show the prototype of the power of fixed-wing aircraft. Utility Model Content

[0004] The utility model aims to provide a fixed-wing aircraft power prototype demonstrator which can visually display the fluid change phenomenon when the airflow passes through the wing-shaped structure which is invisible to the naked eye.

[0005] The purpose of the utility model is achieved in this way, including a demonstration platform and a control device, a stand is provided on the demonstration platform, a wing model that can be freely raised and lowered is provided on the stand, a variable frequency fan is provided on one side of the demonstration platform, an air duct is provided at the air outlet of the variable frequency fan, the air outlet of the air duct is facing the direction of the wing model, a concave mirror is provided on the demonstration platform on the rear side of the wing model, a Schlieren imaging device is provided on the demonstration platform at twice the focal length of the center of the concave mirror, a display connected to the Schlieren imaging device is provided on the demonstration platform, and the control device is connected to the variable frequency fan.

[0006] Furthermore, a heating element is arranged in the air duct.

[0007] Furthermore, the stand includes a base plate and two vertical rods arranged on the base plate, a cross rod is arranged between the two vertical rods, two ends of the cross rod are respectively connected to the two vertical rods in a freely sliding manner, and the wing model is installed on the cross rod.

[0008] Furthermore, a spring is arranged on the vertical rod below the horizontal rod.

[0009] Furthermore, a track is provided on the demonstration platform along its length direction, and the Schlieren imaging device is slidably installed on the track.

[0010] Furthermore, a flow equalizing net is provided at the air outlet end of the air duct.

[0011] The utility model is used for demonstrating the power prototype of fixed-wing aircraft, can be used for display in science and technology museums, and can also be used for teaching. During the display process, the variable frequency fan and the schlieren imaging device are started. The schlieren imaging device is a prior art and generally includes components such as a point light source, a high-speed camera, and a blade. The variable frequency fan generates an airflow, which is blown toward the wing model through an air duct. The wing model is continuously raised under the action of the airflow. At the same time, the light generated by the point light source is directed toward the wing model, passes through the airflow field around the wing model, and then continues to be directed toward the concave mirror. After being reflected by the concave mirror, the received image is recorded by the high-speed camera and transmitted to a display for display. In the present invention, the principle of Schlieren method is adopted to visualize the airflow. The principle is to use the refractive index gradient of light in the flow field to be proportional to the airflow density in the flow field, and to convert the change of density gradient in the flow field into the change of relative light intensity on the recording plane, so that the area with drastic density change in the compressible flow field becomes an observable and distinguishable image and is recorded. The colorless airflow under high-speed flow state is visualized on the display by the Schlieren method, and people can intuitively observe the airflow state around the wing model, especially the upper and lower sides and the rear side of the wing model with the naked eye. At the same time, people can also observe the situation of the area near the wing model while observing the image displayed on the display. The two are combined and compared with each other, and the airflow changes that are invisible to the naked eye are visualized on the display, which is more conducive to people's understanding of the airflow changes of the power prototype of the fixed-wing aircraft and improves the demonstration effect. Secondly, when the present invention is demonstrated, on the one hand, a variable frequency fan is arranged to generate dynamic airflow to blow to the machine The wing model is used to simulate the thrust of the aircraft during flight. On the other hand, a wing model that can be freely raised and lowered is set. The wing model will continue to rise under the action of the above-mentioned airflow to simulate the lift of the aircraft during flight. The entire demonstration process is a dynamic demonstration form. Compared with the currently commonly used static demonstration form, the demonstration process is more vivid, which can well demonstrate the operation trajectory of the wing model and make it easier for people to understand the power prototype of fixed-wing aircraft. In addition, people can control the wind force generated by the variable frequency fan through the control device. When the wind force increases, the wing model rises on the stand, and conversely, when the wind force decreases, the wing model descends on the stand. During the lifting and lowering process of the wing model, the changes in the airflow around it are always displayed on the display through the Schlieren imaging device. While people have a better sense of experience and participation, it is easier for people to observe and understand the power prototype of the aircraft, and it can also better reflect the dynamic relationship between force and the wing model, thereby improving the demonstration effect. In summary, the utility model has the advantages of being able to intuitively display the phenomenon of fluid changes when the airflow passes through the wing-shaped structure, which is invisible to the naked eye, and the generated force on the aircraft model has the advantages of scientificity, objective authenticity and visual demonstration effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the overall structure of the utility model;

[0013] Figure 2 It is a schematic diagram of the principle of the Schlieren imaging method in the utility model;

[0014] Figure 3 This is a schematic diagram of the structure of the neutral frame of the utility model;

[0015] In the figure: 1-demonstration table, 2-control device, 3-wing model, 4-frequency conversion fan, 5-air duct, 6-concave mirror, 7-schlieren imaging device, 8-display, 9-heating element, 10-bottom plate, 11-vertical rod, 12-cross rod, 13-spring, 14-track, 15-flow equalizing network, 16-point light source, 17-high-speed camera. DETAILED DESCRIPTION

[0016] The present invention is further described below in conjunction with the accompanying drawings, but the present invention is not limited in any way. Any changes or improvements made based on the present invention belong to the protection scope of the present invention.

[0017] like Figures 1 to 3 As shown, the utility model includes a demonstration platform 1 and a control device 2. A stand is provided on the demonstration platform 1. A wing model 3 that can be lifted and lowered freely is provided on the stand. The wing model 3 is used to simulate the wing of a fixed-wing aircraft. A variable frequency fan 4 is provided on one side of the demonstration platform 1. The variable frequency fan 4 is a prior art. When the utility model is actually used, the flow rate of the variable frequency fan 4 is 900m³ / h~1650m³ / h, the power is 0.25p~4p, and the total pressure is 275pa~315pa. A variable frequency fan 4 with special parameters can also be selected as needed. An air duct 5 is provided at the air outlet of the variable frequency fan 4. The air outlet of the air duct 5 faces the direction of the wing model 3. A concave mirror 6 is provided on the demonstration platform 1 on the rear side of the wing model 3. The diameter of the concave mirror 6 in the utility model is 300 mm, the focal length is 1200mm, and a Schlieren imaging device 7 is arranged on the demonstration platform 1 at twice the focal length of the center of the concave mirror 6. The Schlieren imaging device 7 is a prior art and can be purchased and installed on the market as needed. It generally includes a point light source 16, a high-speed camera 17, blades and other components. Combined with the concave mirror 6, the conditions for Schlieren imaging can be met. The wing model 3 to be imaged is placed in front of the concave mirror 6 to achieve Schlieren imaging, and the airflow image around the wing model 3 is obtained. A display 8 connected to the Schlieren imaging device 7 is arranged on the demonstration platform 1, and the control device 2 is connected to the variable frequency fan 4. The display 8 is used to display the image captured in the Schlieren imaging device 7. The operating device 2 is an existing structure, which is used to control the start and stop of the variable frequency fan 4 and the size of the wind force generated.

[0018] The utility model is used for demonstrating the power prototype of fixed-wing aircraft, can be used for display in science and technology museums, and can also be used in teaching and other occasions. During the display process, the variable frequency fan 4 and the schlieren imaging device 7 are started. The schlieren imaging device 7 is a prior art, generally including a point light source 16, a high-speed camera 17, blades and other components. The variable frequency fan 4 generates an airflow, and the airflow is blown toward the wing model 3 through the air duct 5. The wing model 3 is continuously raised under the action of the airflow. At the same time, the light generated by the point light source 16 is directed toward the wing model 3, passes through the airflow field around the wing model 3, and then continues to be directed toward the concave mirror 6. After being reflected by the concave mirror 6, the received image is recorded by the high-speed camera 17 and transmitted to the display 8 for display. Then, the airflow change image around the wing model 3 can be obtained on the display 8. In the present invention, the principle of Schlieren method is adopted to visualize the airflow. The principle is to use the refractive index gradient of light in the flow field to be proportional to the airflow density in the flow field, and convert the change of density gradient in the flow field into the change of relative light intensity on the recording plane, so that the area with drastic density change in the compressible flow field becomes an observable and distinguishable image and is recorded. The colorless airflow under high-speed flow state is visualized on the display 8 by the Schlieren method, and people can intuitively observe the airflow state around the wing model 3, especially the upper and lower sides and the rear side of the wing model 3 with the naked eye. At the same time, people can also observe the situation in the vicinity of the wing model 3 while observing the image displayed on the display 8. The two are combined and compared with each other, and the airflow changes that are invisible to the naked eye are visualized on the display 8, which is more conducive to people's understanding of the airflow changes of the power prototype of the fixed-wing aircraft and improves the demonstration effect. Secondly, when the present invention is demonstrated, on the one hand, a variable frequency fan 4 is set to generate dynamic airflow to blow to the wing model Type 3 is used to simulate the thrust of the aircraft during flight. On the other hand, a wing model 3 that can be freely raised and lowered is provided. The wing model 3 will continue to rise under the action of the above-mentioned airflow to simulate the lift of the aircraft during flight. The entire demonstration process is a dynamic demonstration form. Compared with the currently commonly used static demonstration form, the demonstration process is more vivid, which can well demonstrate the running trajectory of the wing model 3, and is also more convenient for people to understand the power prototype of the fixed-wing aircraft; in addition, people can control the wind force generated by the variable frequency fan 4 through the control device 2. When the wind force increases, the wing model 3 rises on the stand, conversely, when the wind force decreases, the wing model 3 descends on the stand, and during the lifting process of the wing model 3, the changes in the airflow around it are always displayed on the display 8 through the schlieren imaging device 7. While people have a better sense of experience and participation, it is more convenient for people to observe and understand the power prototype of the aircraft, and can also better reflect the dynamic relationship between the force and the wing model 3, thereby improving the demonstration effect.

[0019] A heating element 9 is provided in the air duct 5. The heating element 9 is a prior art and is provided in the air duct 5 to heat the airflow in the air duct 5. The heated airflow can form a more obvious cold and hot convection effect with the surrounding cold air, thereby improving the visualization effect of the airflow on the display 8 and making the airflow image captured by the Schlieren method clearer. It has been verified in practice that when the airflow temperature is heated to 40°C to 60°C, the airflow has a better visualization effect on the display 8. In actual use, in order to better heat the airflow, a plurality of heating tubes are selected, and the heating tubes are evenly spaced on the cross section of the air duct 5, while minimizing wind resistance, the airflow is evenly heated to improve the heating efficiency and heating effect of the airflow.

[0020] Preferably, the stand comprises a base plate 10 and two vertical rods 11 arranged on the base plate 10, a cross bar 12 is arranged between the two vertical rods 11, and the two ends of the cross bar 12 are respectively connected to the two vertical rods 11 for free sliding, and the wing model 3 is mounted on the cross bar 12. In the utility model, the wing model 3 rises or falls upward or downward under the action of the airflow, and then drives the cross bar 12 to move up and down along the vertical rods 11, and the vertical rods 11 have the functions of guiding and limiting. The detailed structure of the stand can also use other structural forms to ensure that the wing model 3 can rise or fall freely under the action of the airflow.

[0021] A spring 13 is arranged on the vertical rod 11 below the cross bar 12. During the demonstration process of the utility model, the cross bar 12 can slide freely up and down along the vertical rod 11. When the demonstration is completed and the power is turned off, the variable frequency fan 4 stops running, and there is no airflow blowing to the wing model 3. The wing model 3 falls under the action of its own gravity. When it falls to the bottom of the vertical rod 11, a collision will occur between the cross bar 12 and the bottom plate 10, which will generate noise and vibration. The vibration is transmitted to the wing model 3 and the demonstration platform 1, and then to the schlieren imaging device 7, demonstrator 8 and other components on the demonstration platform 1, reducing the service life of each component. In order to solve this problem, a spring 13 is arranged between the cross bar 12 and the bottom plate 10 to improve the effects of noise reduction, buffering and vibration reduction, and extend the service life of each component.

[0022] A track 14 is provided on the demonstration platform 1 along its length direction, and the Schlieren imaging device 7 is slidably installed on the track 14. During the installation and demonstration process of the utility model, it may be necessary to adjust the position of the Schlieren imaging device 7, and the Schlieren imaging device 7 needs to be moved to a position near the twice focal length of the concave mirror 6. During the demonstration process, the position of the Schlieren imaging device 7 is fine-tuned so as to obtain a clear airflow image on the display 8. The track 14 is provided for easy operation, and the Schlieren imaging device 7 can slide on the track 14. When operating, it is only necessary to push the Schlieren imaging device 7 to slide on the track 14. At the same time, considering that the Schlieren imaging device 7 is a high-value precision instrument, through the provision of the track 14, the Schlieren imaging device 7 only needs to slide when moving its position, thereby avoiding operations such as picking up and putting down, thereby reducing vibration, increasing its service life, and reducing the possibility of accidental falling and damage.

[0023] A flow balancing net 15 is provided at the air outlet end of the air duct 5. During the demonstration process of the utility model, the variable frequency fan 4 generates airflow, and the airflow blows toward the wing model 3 after passing through the air duct 5. During the demonstration process, it is found that after the airflow is blown out from the air duct 5, there is a problem of uneven distribution, and the uneven wind force blowing toward the wing model 3 will reduce the visualization effect of the airflow distribution around the wing model 3 in the display 8, thereby reducing the demonstration effect of the utility model. In order to change this problem, a flow balancing net 15 is provided. The flow balancing net 15 is a prior art, which can evenly arrange the airflow, so that the airflow can be evenly blown toward the wing model 3 when it is blown out from the air duct 5, thereby improving the demonstration effect of the entire demonstrator; in addition, the flow balancing net 15 also has a protective function, preventing people, especially children, from putting their hands into the air duct 5, thereby improving the safety of the device during demonstration.

[0024] In actual use, for safety and protection considerations, a protective cover can be made of transparent acrylic material on the demonstration platform 1 to cover all components except the control device 2. Under the premise of not affecting the demonstration effect, the safety during the demonstration is improved, and each component is protected to prevent each component from being touched, collided, dusted, or wet, thereby extending the service life of each component. For space saving considerations, the part of the demonstration platform 1 between the wing model 3 and the schlieren imaging device 7 can also be set as a push-pull structure, that is, when performing a demonstration, this part of the demonstration platform 1 is stretched, and vice versa, this part of the demonstration platform 1 is retracted. In order to improve the demonstration effect, an airplane model can also be placed on the demonstration platform 1.

[0025] The principle of Schlieren imaging is mainly based on the refraction and reflection of light. It visualizes airflow and other physical phenomena by capturing the change in refractive index caused by changes in airflow density. This technology utilizes the change in refractive index when light propagates in media of different densities. When light passes through a medium with uneven density, it will be deflected, resulting in changes in light and dark on the imaging plane, forming an observable image. When light passes through a medium with different densities, such as the junction of hot air and cold air, the light will be refracted or bent. The degree of this refraction depends on the refractive index of the medium, which in turn varies with factors such as the temperature, pressure and composition of the medium. Therefore, by observing the deflection of light in the medium, the change in medium density can be inferred, and then the airflow and other physical phenomena can be visualized. In general, Schlieren imaging technology realizes the visualization of invisible airflow and other physical phenomena by capturing and recording the refraction and reflection of light in a medium with uneven density. It is an important tool in scientific research and technological applications. The utility model adopts the method of Schlieren imaging, combined with the variable frequency fan 4, the wing model 3 and other parts, to demonstrate the power prototype of the fixed-wing aircraft. The structure is simple, the whole demonstration process is more vivid, it is easy for people to understand, deepens people's impression, and has a good demonstration effect.

Claims

1. A fixed-wing aircraft power prototype demonstrator, comprising a demonstration platform (1) and a control device (2), characterized in that The demonstration platform (1) is provided with a stand, and a freely liftable wing model (3) is provided on the stand. A variable frequency fan (4) is provided on one side of the demonstration platform (1). An air duct (5) is provided at the air outlet of the variable frequency fan (4), and the air outlet of the air duct (5) faces the direction of the wing model (3). A concave mirror (6) is provided on the demonstration platform (1) at the rear side of the wing model (3). A schlieren imaging device (7) is provided on the demonstration platform (1) at twice the focal length of the center of the concave mirror (6). A display (8) connected to the schlieren imaging device (7) is provided on the demonstration platform (1). The control device (2) is connected to the variable frequency fan (4).

2. A fixed-wing aircraft power prototype demonstrator according to claim 1, characterized in that A heating element (9) is arranged in the air duct (5).

3. The fixed-wing aircraft power prototype demonstrator according to claim 1, characterized in that The stand comprises a base plate (10) and two vertical rods (11) arranged on the base plate (10), a cross rod (12) is arranged between the two vertical rods (11), two ends of the cross rod (12) are respectively connected to the two vertical rods (11) in a freely slidable manner, and the wing model (3) is mounted on the cross rod (12).

4. A fixed-wing aircraft power prototype demonstrator according to claim 3, characterized in that A spring (13) is provided on the vertical rod (11) below the horizontal rod (12).

5. The fixed-wing aircraft power prototype demonstrator according to claim 1, characterized in that The demonstration platform (1) is provided with a track (14) along its length direction, and the schlieren imaging device (7) is slidably mounted on the track (14).

6. The fixed-wing aircraft power prototype demonstrator according to claim 1, characterized in that The air outlet end of the air duct (5) is provided with a flow equalizing net (15).

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