A device and method for measuring the lift of an airfoil

Abstract

The present invention discloses a device for measuring the lift of an airfoil, which is used to be placed in a wind tunnel. The device includes: two first columns, which are arranged vertically and oppositely; two upper flat plates, which are arranged horizontally and are respectively fixed at the upper ends of the corresponding first columns; two lower flat plates, which are arranged horizontally and are respectively fixed at the lower ends of the corresponding first columns; two linear guides, which are arranged vertically and oppositely, and whose two ends are respectively fixed on the corresponding upper flat plates and lower flat plates; two bearings, which are arranged oppositely and are respectively sleeved on the two linear guides. After the airfoil receives the upward or downward lift in the wind tunnel, the airfoil drives the bearings to move upward or downward along the linear guides, thereby measuring the upward or downward displacement value of the airfoil and obtaining the magnitude of the lift of the airfoil. The present invention is simple, reliable and intuitive; the present invention does not require a wind tunnel balance, reducing the experimental cost; the present invention can change the angle of attack of the airfoil by setting a motor and can measure multiple groups of data.

Description

Technical Field

[0001] The present invention belongs to the field of airfoil test equipment, and particularly relates to a device and method for measuring the lift of an airfoil. Background Art

[0002] An airfoil refers to the cross-section perpendicular to the leading edge on the wings, tail fins, missile wing surfaces, helicopter rotor blades, and propeller blades of an aircraft. For an aircraft, the airfoil is an important part of the wing and tail fin, directly determining the aerodynamic performance and flight quality of the aircraft.

[0003] In wind tunnel experiments, common airfoil test methods include the airfoil surface pressure measurement method and the balance force measurement method.

[0004] The pressure measurement method refers to opening a series of pressure measurement holes on the model surface and obtaining the lift and moment of the model through the integration of the surface pressure. There are the following disadvantages in using the pressure measurement method to measure the aerodynamic force of an airfoil:

[0005] 1. A large number of pressure measurement tubes need to be connected before the experiment, resulting in a high time cost;

[0006] 2. During the experiment, the pressure measured on the surface needs to be converted into a pressure coefficient and then integrated to obtain the aerodynamic coefficient, and the result is not intuitive.

[0007] The force measurement method refers to using a force measurement balance to obtain the aerodynamic force of the model. There are the following disadvantages in using the balance to measure the aerodynamic force of an airfoil:

[0008] 1. The balance is a precision measurement device and is easily damaged during use;

[0009] 2. The balance needs to be calibrated before use, and the process is relatively cumbersome.

[0010] Neither of the above two methods can meet the requirements of simple, fast, and intuitive quantitative demonstration of airfoil lift. Summary of the Invention

[0011] The purpose of the present invention is to provide a device and method for measuring the lift of an airfoil to solve the problems of long time, cumbersome process, high cost, and non-intuitive measurement results in measuring the lift of an airfoil.

[0012] The present invention adopts the following technical solutions: A device for measuring the lift of an airfoil, which is used to be placed in a wind tunnel and includes:

[0013] Two first columns, which are arranged opposite to each other and vertically,

[0014] Two upper flat plates, which are arranged horizontally and are respectively fixed at the upper ends of the corresponding first columns,

[0015] Two lower flat plates, which are arranged horizontally and are respectively fixed at the lower ends of the corresponding first columns,

[0016] Two linear guide rails are vertically and oppositely arranged, and their two ends are respectively fixed on the corresponding upper flat plate and lower flat plate.

[0017] Two bearings are oppositely arranged and sleeved on the two linear guide rails respectively. The two bearings are respectively used to fix the two ends of the airfoil, so that the airfoil is horizontally fixed between the two bearings.

[0018] Two upper springs are respectively sleeved on the upper half of the linear guide rails. Their upper ends are fixed and their lower ends abut against the upper ends of the corresponding side bearings.

[0019] Two lower springs are respectively sleeved on the lower half of the linear guide rails. Their lower ends are fixed and their upper ends abut against the lower ends of the corresponding side bearings.

[0020] Wherein, the two bearings are also used for the airfoil to drive the bearings to move up or down along the linear guide rails after receiving the upward or downward lift force in the wind tunnel, so as to measure the upward or downward displacement value of the airfoil and obtain the magnitude of the lift force of the airfoil.

[0021] Furthermore, there are also two second columns which are oppositely and vertically arranged. One ends of the two upper flat plates are respectively fixedly connected to the upper ends of the first columns, and the other ends are respectively fixedly connected to the upper ends of the corresponding second columns. One ends of the two lower flat plates are respectively fixedly connected to the lower ends of the first columns, and the other ends are respectively fixedly connected to the lower ends of the corresponding second columns. The two first columns, the two second columns, the two upper flat plates and the two lower flat plates cooperate with each other to form two opposite frame-shaped areas, and the two frame-shaped areas are both used to accommodate the linear guide rails, the bearings, the upper springs and the lower springs.

[0022] Furthermore, upper support plates and lower support plates are fixedly connected between the first column and the second column in the same frame-shaped area. The two ends of the two upper support plates and the lower support plates are respectively fixedly connected to the inner sides of the corresponding first column and the second column. The two upper support plates and the lower support plates are both arranged parallel to the upper flat plate. The two ends of the two linear guide rails are respectively fixed on the corresponding upper support plates and lower support plates. The first column, the second column, the upper support plates and the lower support plates in the same frame-shaped area cooperate with each other to form an accommodation space, and the accommodation space is used to accommodate the linear guide rails, the bearings, the upper springs and the lower springs.

[0023] Furthermore, a motor is fixedly connected to one bearing, and the output shaft of the motor is sleeved with the shaft of the airfoil. The motor is used to rotate the airfoil through the shaft of the airfoil, so as to change the angle of attack of the airfoil.

[0024] Furthermore, the other bearing fixes one end of the airfoil through a fixing member. The fixing member is fixedly connected to the corresponding bearing, and the fixing member and the motor cooperate with each other to fix the airfoil by fixing the shaft of the airfoil.

[0025] Further, a scale is adhered to any one of the two first columns or the two second columns from top to bottom, and a horizontally arranged pointer is fixedly connected to any one of the bearings. The pointer and the scale are arranged opposite to each other. The pointer is used to mark the upward or downward displacement value of the bearing, and the lift force of the airfoil is obtained by reading the value.

[0026] Further, an upper cross beam is fixedly connected between the two upper flat plates, and a lower cross beam is fixedly connected between the two lower flat plates. The upper cross beam, the lower cross beam, the two first columns, and the two second columns cooperate with each other to form a region for accommodating the airfoil.

[0027] Further, a base is fixedly connected below the lower cross beam, and a level is installed on the base. The base is used to support the entire device and is convenient to be placed in the wind tunnel.

[0028] A method for measuring the lift force of an airfoil based on the above device consists of the following steps:

[0029] Select two suitable end plates and sleeved them on both ends of the airfoil so that two-dimensional flow is generated on the airfoil.

[0030] Fix both ends of the airfoil between two bearings respectively.

[0031] Place the device for measuring the lift force of the airfoil in the wind tunnel.

[0032] Read the upward or downward displacement value of the pointer.

[0033] Start the motor and change the angle of attack of the airfoil.

[0034] Read the upward or downward displacement value of the pointer again until the measurement is completed.

[0035] The beneficial effects of the present invention are as follows: The present invention is simple, reliable, and intuitive; the present invention does not require a wind tunnel balance, reducing the experimental cost; the measurement result of the present invention is concise and intuitive; the present invention can change the angle of attack of the airfoil by setting a motor and can measure multiple groups of data; the present invention can also be used for demonstrating the mechanism of lift force generation of the airfoil and the variation law of the lift force of the airfoil with the angle of attack, wind speed, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic structural diagram of the present invention;

[0037] Figure 2 It is a schematic structural diagram of one side of the motor of the present invention;

[0038] Figure 3 It is a detailed view of the scale of the present invention.

[0039] Wherein: 1. The first column; 2. The upper flat plate; 3. The lower flat plate; 4. The linear guide rail; 5. The bearing; 6. The upper spring; 7. The lower spring; 8. The second column; 9. The upper support plate; 10. The lower support plate; 11. The fixing member; 12. The scale; 13. The pointer; 14. The upper cross beam; 15. The lower cross beam; 16. The base; 17. The motor; 18. The airfoil; 19. The end plate. Specific embodiments

[0040] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0041] The present invention discloses a device for measuring the lift of an airfoil, which is used to be placed in a wind tunnel. As Figure 1 shown, the device includes two first columns 1, two upper flat plates 2, two lower flat plates 3, two linear guide rails 4, two bearings 5, two upper springs 6, and two lower springs 7.

[0042] The two first columns 1 are arranged opposite to each other and vertically. The two upper flat plates 2 are arranged horizontally, and the two upper flat plates 2 are respectively fixed to the upper ends of the corresponding first columns 1. The two lower flat plates 3 are arranged horizontally, and the two lower flat plates 3 are respectively fixed to the lower ends of the corresponding first columns 1. The two linear guide rails 4 are arranged vertically and opposite to each other, and the two ends of the two linear guide rails 4 are respectively fixed to the corresponding upper flat plates 2 and lower flat plates 3. The two bearings 5 are arranged opposite to each other, and the two bearings 5 are respectively sleeved on the two linear guide rails 4. The two bearings 5 are respectively used to fix the two ends of the airfoil 18, so that the airfoil 18 is horizontally fixed between the two bearings 5. As Figure 2 shown, the two upper springs 6 are respectively sleeved on the upper half of the linear guide rail 4. The upper ends of the two upper springs 6 are fixed and the lower ends abut against the upper ends of the corresponding side bearings 5. The two lower springs 7 are respectively sleeved on the lower half of the linear guide rail 4. The lower ends of the two lower springs 7 are fixed and the upper ends abut against the lower ends of the corresponding side bearings 5. The two bearings 5 are also used for the airfoil 18 to drive the bearings 5 to move up or down along the linear guide rail 4 after receiving the upward or downward lift in the wind tunnel, thereby measuring the upward or downward displacement value of the airfoil 18 and obtaining the magnitude of the lift of the airfoil 18.

[0043] The present invention installs the linear guide rail 4 by setting two first columns 1, two upper flat plates 2, and two lower flat plates 3, and by sleeving the bearing 5 on the linear guide rail 4, the bearing 5 can slide up and down along the linear guide rail 4 after being stressed. By fixing the airfoil 18 between the two bearings 5, when the bearing 5 moves up or down, the displacement value of the bearing 5 is measured, and thus the lift of the airfoil 18 can be obtained. The structure is simple and reliable, and the obtained result is intuitive. There is no need to perform integration to obtain the aerodynamic coefficient and conversion to obtain the magnitude of the lift.

[0044] The device further includes two second vertical columns 8 arranged oppositely. One end of each of the two upper flat plates 2 is fixedly connected to the upper end of the first column 1, and the other end of each of the two upper flat plates 2 is fixedly connected to the upper end of the corresponding second column 8. One end of each of the two lower flat plates 3 is fixedly connected to the lower end of the first column 1, and the other end of each of the two lower flat plates 3 is fixedly connected to the lower end of the corresponding second column 8. The two first columns 1, the two second columns 8, the two upper flat plates 2, and the two lower flat plates 3 cooperate with each other to form two opposite frame-shaped areas, and both of the two frame-shaped areas are used to accommodate the linear guide 4, the bearing 5, the upper spring 6, and the lower spring 7.

[0045] By providing the second column 8, the area for accommodating the bearing 5 and the linear guide 4 can be enclosed, enabling the linear guide 4 to be installed more stably, and thus making the measured data more accurate. Moreover, by providing the second column 8, the second column 8 and the first column 1 cooperate with each other, making the device more compact and complete, facilitating movement, and ensuring the accuracy of the measurement results.

[0046] Upper support plates 9 and lower support plates 10 are fixedly connected between the first column 1 and the second column 8 in the same frame-shaped area. The two ends of the two upper support plates 9 and the lower support plates 10 are fixedly connected to the inner sides of the corresponding first column 1 and the second column 8 respectively. The two upper support plates 9 and the lower support plates 10 are arranged parallel to the upper flat plate 2. The two ends of the two linear guides 4 are fixedly connected to the corresponding upper support plates 9 and lower support plates 10 respectively. The first column 1, the second column 8, the upper support plates 9, and the lower support plates 10 in the same frame-shaped area cooperate with each other to form an accommodation space, and the accommodation space is used to accommodate the linear guide 4, the bearing 5, the upper spring 6, and the lower spring 7.

[0047] Since the lift force of the airfoil 18 is relatively small, the amplitude of the upward or downward movement of the bearing 5, that is, the displacement value, is relatively small. Therefore, if the two ends of the linear guide 4 are fixed to the upper flat plate 2 and the lower flat plate 3, a relatively long linear guide 4 is required, and the distance between the upper flat plate 2 and the lower flat plate 3 cannot be too small because the airfoil 18 needs to be accommodated. Therefore, by providing the upper support plates 9 and the lower support plates 10, the two ends of the linear guide 4 are fixed to the upper support plates 9 and the lower support plates 10, which not only meets the requirement of accommodating the airfoil 18 but also meets the requirement of setting a shorter linear guide 4, saving costs.

[0048] One of the bearings 5 is also fixedly connected with a motor 17. The output shaft of the motor 17 is sleeved with the shaft of the airfoil 18. The motor 17 is used to rotate the airfoil 18 through the shaft of the airfoil 18, thereby changing the angle of attack of the airfoil 18, and then multiple groups of data can be measured; that is, the lift force on the airfoil 18 at multiple angles can be measured to ensure the comprehensiveness of the final experimental results. If the motor 17 is not set, the airfoil 18 needs to be rotated manually multiple times to obtain the required angle of attack of the airfoil 18 by manual rotation. By setting the motor 17, the required angle of attack of the airfoil 18 can be obtained by rotating the motor 17, shortening the measurement time, with simple operation and not cumbersome.

[0049] The other bearing 5 fixes one end of the airfoil 18 through a fixing member 11. The fixing member 11 is fixedly connected with the corresponding bearing 5. The fixing member 11 and the motor 17 cooperate to fix the airfoil 18 by fixing the shaft of the airfoil 18. There is no requirement for the shape of the fixing member 11. It can fix the shaft of the airfoil 18 through a clamp or other means, as long as the shaft of the airfoil 18 is fixed to fix the airfoil 18.

[0050] Such as Figure 3 As shown, a scale 12 is pasted from top to bottom on any one of the two first columns 1 or the two second columns 8. A pointer 13 is also fixedly connected to any one of the bearings 5. The pointer 13 and the scale 12 are arranged opposite to each other. The pointer 13 is used to mark the upward or downward displacement value of the bearing 5, and the lift force of the airfoil 18 is obtained by reading the value. By setting the scale 12 and the pointer 13, the upward or downward displacement value of the bearing 5 can be observed quickly from outside the wind tunnel, and then the lift force of the airfoil 18 can be judged, which is convenient for operation and accurate in reading.

[0051] An upper cross beam 14 is also fixedly connected between the two upper flat plates 2, and a lower cross beam 15 is also fixedly connected between the two lower flat plates 3. The upper cross beam 14, the lower cross beam 15, the two first columns 1, and the two second columns 8 cooperate with each other to form a region for accommodating the airfoil 18. By setting the upper cross beam 14 and the lower cross beam 15, the region for accommodating the airfoil 18 can be enclosed, making the airfoil 18 more firmly fixed between the two bearings 5, and then making the measured data more accurate. Moreover, by setting the upper cross beam 14 and the lower cross beam 15, the upper cross beam 14, the lower cross beam 15, the first column 1 and the second column 8 cooperate with each other, making the device more compact and complete, convenient for movement, and ensuring the accuracy of the measurement results.

[0052] A base 16 is also fixedly connected below the lower cross beam 15. A spirit level is installed on the base 16. The base 16 is used to support the whole device and is convenient for placing in the wind tunnel. By setting the base 16 and installing a spirit level on the base 16, it is convenient to adjust the horizontal state of the whole device and convenient to place this device.

[0053] In the present invention, the spring is a special spring, and its elastic modulus is designed such that under the maximum negative or positive lift condition of the airfoil 18, the displacement above and below the model is within an appropriate range; the motor 17 is selected based on the fact that the holding torque of the motor 17 can enable the airfoil 18 to freely adjust its angle under the conditions of maximum wind speed and maximum torque; the scale 12 and the spring are calibrated in advance.

[0054] The present invention also discloses a method for measuring the lift of an airfoil using the above device, which consists of the following steps:

[0055] Select two suitable end plates 19 and sleeved them at both ends of the airfoil 18, so that two-dimensional flow is generated on the airfoil 18 by the end plates 19.

[0056] Fix both ends of the airfoil 18 between two bearings 5 respectively.

[0057] Place the device for measuring the lift of the airfoil in a wind tunnel.

[0058] Read the upward or downward displacement value of the pointer 13.

[0059] Turn on the motor 17 to change the angle of attack of the airfoil 18.

[0060] Read the upward or downward displacement value of the pointer 13 again until the measurement is completed.

[0061] The usage method of the device in the present invention is as follows:

[0062] Fix the entire device in a wind tunnel. Before the experiment starts, select two suitable end plates 19 and sleeved them at both ends of the airfoil 18, so that two-dimensional flow is generated on the airfoil 18 by the end plates 19; fix the airfoil 18 on the bearing 5 between the upper spring 6 and the lower spring 7 and keep it stationary. At this time, the pointer 13 points to a scale, and this scale is the weight of the airfoil 18. When the experiment starts, that is, when the wind tunnel starts to operate, due to the upward or downward lift received by the airfoil 18, the airfoil 18 drives the bearing 5 to compress the upper spring 6 or the lower spring 7, driving the pointer 13 to move. According to the force value indicated by the pointer 13 on the scale 12, the magnitude of the lift of the airfoil 18 is obtained.

Claims

1. A device for measuring the lift of an airfoil, characterized in that, For placement in a wind tunnel, comprising: Two first columns (1), arranged opposite to each other and vertically, Two upper flat plates (2), arranged horizontally and respectively fixed to the upper ends of the corresponding first columns (1), Two lower flat plates (3), arranged horizontally and respectively fixed to the lower ends of the corresponding first columns (1), Two linear guide rails (4), arranged vertically and opposite to each other, with their two ends respectively fixed to the corresponding upper flat plates (2) and lower flat plates (3), Two bearings (5), arranged opposite to each other and respectively sleeved on the two linear guide rails (4), and the two bearings (5) are respectively used to fix the two ends of the airfoil (18), so that the airfoil (18) is horizontally fixed between the two bearings (5), Two upper springs (6), respectively sleeved on the upper half of the linear guide rails (4), with their upper ends fixed and their lower ends abutting against the upper ends of the corresponding bearings (5), Two lower springs (7), respectively sleeved on the lower half of the linear guide rails (4), with their lower ends fixed and their upper ends abutting against the lower ends of the corresponding bearings (5), Two end plates (19), respectively sleeved on the two ends of the airfoil (18); Wherein, the two bearings (5) are also used for after the airfoil (18) receives an upward or downward lift force in the wind tunnel, the airfoil (18) drives the bearings (5) to move upward or downward along the linear guide rails (4), thereby measuring the upward or downward displacement value of the airfoil (18) and obtaining the magnitude of the lift force of the airfoil (18); Wherein, one of the bearings (5) is also fixedly connected to a motor (17), the output shaft of the motor (17) is sleeved with the shaft of the airfoil (18), the motor (17) is used to rotate the airfoil (18) through the shaft of the airfoil (18), thereby changing the angle of attack of the airfoil (18), and the other bearing (5) fixes one end of the airfoil (18) through a fixing member (11), the fixing member (11) is fixedly connected to the corresponding bearing (5), and the fixing member (11) and the motor (17) cooperate with each other to fix the airfoil (18) by fixing the shaft of the airfoil (18).

2. The device for measuring the lift of an airfoil according to claim 1, wherein It further comprises two second columns (8) arranged opposite to each other and vertically. One ends of the two upper flat plates (2) are respectively fixedly connected to the upper ends of the first columns (1), and the other ends are respectively fixedly connected to the upper ends of the corresponding second columns (8). One ends of the two lower flat plates (3) are respectively fixedly connected to the lower ends of the first columns (1), and the other ends are respectively fixedly connected to the lower ends of the corresponding second columns (8). The two first columns (1), the two second columns (8), the two upper flat plates (2), and the two lower flat plates (3) cooperate with each other to form two opposite frame-shaped areas, and the two frame-shaped areas are both used to accommodate the linear guide rails (4), the bearings (5), the upper springs (6), and the lower springs (7).

3. The device for measuring the lift of an airfoil according to claim 2, characterized in that, Upper support plates (9) and lower support plates (10) are fixedly connected between the first upright post (1) and the second upright post (8) located in the same frame-shaped area. The two ends of the two upper support plates (9) and lower support plates (10) are fixedly connected to the inner sides of the corresponding first upright post (1) and second upright post (8) respectively. The two upper support plates (9) and lower support plates (10) are arranged parallel to the upper flat plate (2). The two ends of the two linear guide rails (4) are fixed to the corresponding upper support plates (9) and lower support plates (10) respectively. The first upright post (1), second upright post (8), upper support plate (9) and lower support plate (10) located in the same frame-shaped area cooperate with each other to form an accommodation space, and the accommodation space is used to accommodate the linear guide rail (4), bearing (5), upper spring (6) and lower spring (7).

4. A method for measuring the lift of an airfoil using the device according to any one of claims 1-3, characterized in that, It consists of the following steps: Select two suitable end plates (19) and sleeved on both ends of the airfoil (18) so that the end plates (19) generate two-dimensional flow on the airfoil (18). Fix both ends of the airfoil (18) between the two bearings (5) respectively. Place the device for measuring the lift of the airfoil in the wind tunnel. Read the upward or downward displacement value of the pointer (13). Start the motor (17) to change the angle of attack of the airfoil (18). Read the upward or downward displacement value of the pointer (13) again until the measurement is completed. The device for measuring the lift of the airfoil is used to be placed in the wind tunnel and includes: Two first upright posts (1), which are arranged opposite to each other and vertically. Two upper flat plates (2), which are arranged horizontally and fixed to the upper ends of the corresponding first upright posts (1) respectively. Two lower flat plates (3), which are arranged horizontally and fixed to the lower ends of the corresponding first upright posts (1) respectively. Two linear guide rails (4), which are arranged vertically and opposite to each other, and the two ends are fixed to the corresponding upper flat plates (2) and lower flat plates (3) respectively. Two bearings (5), which are arranged opposite to each other and sleeved on the two linear guide rails (4) respectively. The two bearings (5) are respectively used to fix both ends of the airfoil (18) so that the airfoil (18) is horizontally fixed between the two bearings (5). Two upper springs (6), which are respectively sleeved on the upper half of the linear guide rail (4), and the upper ends are fixed and the lower ends abut against the upper ends of the corresponding side bearings (5). Two lower springs (7), which are respectively sleeved on the lower half of the linear guide rail (4), and the lower ends are fixed and the upper ends abut against the lower ends of the corresponding side bearings (5). Wherein, the two bearings (5) are also used for the airfoil (18) to drive the bearing (5) to move up or down along the linear guide rail (4) after receiving the upward or downward lift in the wind tunnel, so as to measure the upward or downward displacement value of the airfoil (18) and obtain the lift magnitude of the airfoil (18). It also includes two relatively arranged and vertically disposed second columns (8). One end of each of the two upper flat plates (2) is fixedly connected to the upper end of the first column (1), and the other end is fixedly connected to the upper end of the corresponding second column (8). One end of each of the two lower flat plates (3) is fixedly connected to the lower end of the first column (1), and the other end is fixedly connected to the lower end of the corresponding second column (8). The two first columns (1), the two second columns (8), the two upper flat plates (2), and the two lower flat plates (3) cooperate with each other to form two opposite frame-shaped areas, and both of the two frame-shaped areas are used to accommodate linear guides (4), bearings (5), upper springs (6), and lower springs (7). Upper support plates (9) and lower support plates (10) are fixedly connected between the first column (1) and the second column (8) located in the same frame-shaped area. Both ends of the two upper support plates (9) and the two lower support plates (10) are fixedly connected to the inner sides of the corresponding first column (1) and second column (8). The two upper support plates (9) and the two lower support plates (10) are arranged parallel to the upper flat plate (2). Both ends of the two linear guides (4) are fixed to the corresponding upper support plates (9) and lower support plates (10). The first column (1), the second column (8), the upper support plates (9), and the lower support plates (10) located in the same frame-shaped area cooperate with each other to form an accommodation space, and the accommodation space is used to accommodate linear guides (4), bearings (5), upper springs (6), and lower springs (7). One of the bearings (5) is also fixedly connected to a motor (17). The output shaft of the motor (17) is sleeved with the shaft of the airfoil (18). The motor (17) is used to rotate the airfoil (18) through the shaft of the airfoil (18), thereby changing the angle of attack of the airfoil (18). The other bearing (5) fixes one end of the airfoil (18) through a fixing member (11). The fixing member (11) is fixedly connected to the corresponding bearing (5). The fixing member (11) and the motor (17) cooperate with each other to fix the airfoil (18) by fixing the shaft of the airfoil (18). A scale (12) is pasted from top to bottom on any one of the two first columns (1) or the two second columns (8). A horizontally arranged pointer (13) is also fixedly connected to any one of the bearings (5). The pointer (13) and the scale (12) are arranged opposite to each other. The pointer (13) is used to mark the upward or downward displacement value of the bearing (5), and the lift force magnitude of the airfoil (18) is obtained by reading the value. An upper cross beam (14) is also fixedly connected between the two upper flat plates (2), and a lower cross beam (15) is also fixedly connected between the two lower flat plates (3). The upper cross beam (14), the lower cross beam (15), the two first columns (1), and the two second columns (8) cooperate with each other to form an area for accommodating the airfoil (18). A base (16) is also fixedly connected below the lower cross beam (15). A level is installed on the base (16). The base (16) is used to support the entire device and is convenient to be placed in a wind tunnel.

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