A weak tunnel wall interference device for 1-meter-scale transonic wind tunnel airfoil testing

Abstract

The present invention proposes a device for reducing tunnel wall interference for 1-meter-scale transonic wind tunnel airfoil tests, belonging to the field of wind tunnel testing technology. The device is intended to reduce the interference effects of the upper and lower tunnel walls during transonic wind tunnel airfoil tests. The present invention comprises a test section and a wind tunnel body within a station chamber. The wind tunnel body is located at the exit of the test section and comprises left and right sidewalls, upper and lower air-permeable walls, a hinged seat, an adjustment seat, left and right frames, and upper and lower frames. The sidewalls are solid walls mounted on the left and right frames, with the air-permeable walls connected to the hinged seat on the inflow side and the air-outflow side connected to the adjustment seat on the outflow side. Four ejector slot adjustment plates are positioned on the outside of the left and right sidewalls and upper and lower air-permeable walls. The outflow side is hinged to the wind tunnel body, and the inflow side is connected to a motor-driven pull rod on the station chamber. When closed, the ejector slot adjustment plates make linear contact with the outer sides of the left and right sidewalls and upper and lower air-permeable walls. The present invention can effectively reduce the interference effects of the upper and lower tunnel walls during transonic wind tunnel airfoil tests, thereby improving the data accuracy of airfoil tests conducted in transonic wind tunnels.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind tunnel testing, and in particular relates to a weak tunnel wall interference device for 1-meter-level transonic wind tunnel airfoil testing. Background Art

[0002] An airfoil test involves placing an airfoil model horizontally within a test section and supporting it on the left and right sidewalls. The pressure distribution along the chordwise direction of the airfoil surface at the center section of the airfoil model is measured, and the aerodynamic forces of the airfoil are then determined through integration. Generally, when conducting airfoil tests, the left and right sidewalls of the test section are solid walls, while the upper and lower walls are permeable walls with holes or slots. Using permeable walls with appropriate permeability can reduce the interference effects of the upper and lower walls. During airfoil tests, there are two different types of wall interference effects, namely, upper and lower wall interference and sidewall interference. Since the left and right sidewalls of the wind tunnel test section are solid walls, sidewall interference cannot be effectively eliminated or reduced. Therefore, when conducting airfoil tests, it is necessary to evaluate the effective spanwise two-dimensional area of ​​the airfoil model. This involves identifying areas on both sides of the airfoil model near the center section that are not affected by the left and right sidewalls. The pressure taps used to measure the airfoil pressure distribution must be completely within this two-dimensional area unaffected by the left and right sidewalls. Regarding the interference between the upper and lower tunnel walls in the form of air-permeable walls, considering that the cross-sectional area of ​​the wind tunnel test section is constant, increasing the test section height can reduce the disturbance caused by the upper and lower tunnel walls on the flow around the model. Therefore, airfoil tests are usually carried out in airfoil wind tunnels with a large height-to-width ratio (the aspect ratio is generally 2-4). However, in engineering applications, airfoil tests are often also carried out in conventional transonic wind tunnels.

[0003] Unlike airfoil wind tunnels, the height-to-width ratio of a conventional transonic wind tunnel test section is generally 1. Therefore, when conducting airfoil tests in conventional transonic wind tunnels, the upper and lower tunnel walls interfere with each other more significantly. In particular, compared to airfoil wind tunnels, conventional transonic wind tunnels are wider. To ensure model rigidity, the thickness and chord length of the airfoil model must be designed and processed larger, increasing the model's blockage and further exacerbating the wall interference effect. Upper and lower tunnel wall interference is an inviscid, two-dimensional flow problem. The most effective and direct way to mitigate this interference is to employ a weak wall interference structure to reduce this effect.

[0004] In summary, it is urgent to design a device that can reduce the interference effect of the upper and lower tunnel walls and improve the data accuracy when conducting airfoil tests in transonic wind tunnels. Summary of the Invention

[0005] A brief overview of the present invention is provided below to provide a basic understanding of certain aspects of the present invention. It should be understood that this overview is not an exhaustive overview of the present invention. It is not intended to identify key or important aspects of the present invention, nor is it intended to limit the scope of the present invention. Its purpose is simply to present certain concepts in a simplified form as a prelude to the more detailed description discussed later.

[0006] In view of this, in order to reduce the interference effect of the upper and lower tunnel walls during transonic wind tunnel airfoil tests, the present invention provides a weak tunnel wall interference device for 1-meter-scale transonic wind tunnel airfoil tests.

[0007] Solution: A weak tunnel wall interference device for 1-meter-class transonic wind tunnel airfoil testing, including a test section, a station chamber, an ejection slot adjustment plate, a wind tunnel body, and a motor-driven pull rod;

[0008] The stationary chamber is provided with a test section and a wind tunnel body, the wind tunnel body being located at the outlet side of the test section in the direction of the incoming flow; the test section comprises left and right side walls, upper and lower air permeable walls, a hinged seat, an electric adjustment seat, left and right frames, and upper and lower frames;

[0009] The left and right frames and the upper and lower frames are fixedly connected to form a rectangular frame, the left and right side walls are solid walls installed on the left and right frames, the upper and lower air-permeable walls include a first solid wall panel, a perforated wall panel, and a second solid wall panel, the three being arranged in sequence from the inflow side to the outflow side, the first solid wall panel being movably connected to the perforated wall panel, and the perforated wall panel being fixedly connected to the second solid wall panel; the first solid wall panel is fixedly connected to the hinged seats on the upper and lower frames, the inflow side of the perforated wall panel is hinged to the hinged seat, and the outflow side of the second solid wall panel is connected to the electric adjustment seat installed on the upper and lower frames;

[0010] Four ejection slit adjustment plates are placed on the outside of the left and right side walls and the upper and lower air-permeable walls. The outflow side is hinged on the wind tunnel body, and the inflow side is connected to the motor-driven pull rod fixed on the stationary chamber. When the ejection slit adjustment plates are closed, the ejection slit adjustment plates are in contact with the outer lines of the left and right side walls and the upper and lower air-permeable walls.

[0011] Furthermore, the left and right side walls are 1.2 m high, 3.8 m long, and 12 mm thick.

[0012] Furthermore, the total length of the upper and lower air-permeable walls is 3.8m, the width is 1.2m, and the thickness is 12mm; the length of the first solid wall panel is 398mm, the length of the perforated wall panel is 3190mm, and the length of the second solid wall panel is 212mm.

[0013] Furthermore, a vertical circular hole with a diameter of 10 mm is provided on the hole wall plate.

[0014] Furthermore, the air permeability of the upper and lower air permeable walls reaches 2.8%.

[0015] Furthermore, the electric adjustment seat drives the upper and lower air-permeable walls to adjust outward in a range of 0 to 1.5 degrees.

[0016] The present invention has the following beneficial effects compared to the prior art:

[0017] 1. The present invention significantly reduces the interference effect of the upper and lower cave walls during airfoil tests, improving the flow field environment of the model;

[0018] 2. The flow field pressure distribution of the airfoil model in the test section of the present invention is basically consistent with that in free flow. The airfoil pressure distribution test results are close to interference-free, which makes the obtained airfoil pressure distribution data more consistent with the standard data, providing more reliable data support for the calculation of the airfoil aerodynamic force, and improving the accuracy and credibility of the test results.

[0019] 3. While conventional transonic wind tunnels experience increased blockage due to model strength requirements, the present invention can still effectively alleviate the aggravated tunnel wall interference effect, ensuring the effectiveness of the test under complex conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0021] Figure 1 This is a rear view of a weak tunnel wall interference device used for 1-meter-class transonic wind tunnel airfoil testing;

[0022] Figure 2 This is a diagram showing the positional relationship between the test section, the ejection slot adjustment piece, and the wind tunnel body;

[0023] Figure 3 This is a positional relationship diagram of the articulated seat and the electric adjustment seat;

[0024] Figure 4 It is a structural diagram of the upper and lower air permeable walls;

[0025] Figure 5 This is the comparison curve between the test data and the standard data in the literature when the Mach number Ma=0.73 and the angle of attack α=3.19°.

[0026] In the figure: 1-left and right side walls, 2-upper and lower air permeable walls, 3-hinge seat, 4-electric adjustment seat, 5-left and right frames, 6-upper and lower frames, 7-stationary chamber, 8-injection slit adjustment plate, 9-wind tunnel body, 10-motor drive rod, 11-test section, 21-first solid wall panel, 22-hole wall panel, 23-second solid wall panel. DETAILED DESCRIPTION

[0027] To make the technical solutions and advantages of the embodiments of the present invention more clearly understood, exemplary embodiments of the present invention are further described in detail below with reference to the accompanying drawings. It should be noted that the embodiments described are only a portion of the embodiments of the present invention, and are not an exhaustive list of all embodiments. It should be noted that the embodiments of the present invention and the features thereof may be combined with each other unless they conflict.

[0028] Example 1, reference Figure 1-4 The present embodiment describes a weak tunnel wall interference device for 1-meter-class transonic wind tunnel airfoil testing, comprising a test section 11, a station chamber 7, an ejection slot adjustment plate 8, a wind tunnel body 9, and a motor-driven pull rod 10.

[0029] The stationary chamber 7 is provided with a test section 11 and a wind tunnel body 9, the wind tunnel body 9 being located at the outlet side of the test section 11 in the incoming flow direction; the test section 11 comprises left and right side walls 1, upper and lower air permeable walls 2, a hinged seat 3, an electric adjustment seat 4, left and right frames 5 and upper and lower frames 6;

[0030] The left and right frames 5 and the upper and lower frames 6 are fixedly connected to form a rectangular frame. The left and right side walls 1 are solid walls installed on the left and right frames 5. The upper and lower air-permeable walls 2 include a first solid wall panel 21, a hole wall panel 22, and a second solid wall panel 23. The three are arranged in sequence from the inflow side to the outflow side. The first solid wall panel 21 is movably connected to the hole wall panel 22, and the hole wall panel 22 is fixedly connected to the second solid wall panel 23; the first solid wall panel 21 is fixedly connected to the hinge seat 3 on the upper and lower frames 6, the inflow side of the hole wall panel 22 is hinged to the hinge seat 3, and the outflow side of the second solid wall panel 23 is connected to the electric adjustment seat 4 installed on the upper and lower frames 6;

[0031] Four ejection slit adjustment pieces 8 are placed on the outside of the left and right side walls 1 and the upper and lower air-permeable walls 2. The outflow side is hinged on the wind tunnel body 9, and the inflow side is connected to the motor-driven pull rod 10 fixed on the stationary chamber 7. When the ejection slit adjustment piece 8 is closed, the ejection slit adjustment piece 8 is in contact with the outer line of the left and right side walls 1 and the upper and lower air-permeable walls 2.

[0032] Furthermore, the left and right side walls 1 are 1.2 m high, 3.8 m long, and 12 mm thick.

[0033] Furthermore, the upper and lower air-permeable walls 2 have a total length of 3.8 m, a width of 1.2 m, and a thickness of 12 mm; the first solid wall panel 21 has a length of 398 mm, the perforated wall panel 22 has a length of 3190 mm, and the second solid wall panel 23 has a length of 212 mm.

[0034] Furthermore, the hole wall plate 22 is provided with a vertical circular hole with a diameter of 10 mm.

[0035] Furthermore, the air permeability of the upper and lower air permeable walls 2 reaches 2.8%.

[0036] Furthermore, the electric adjustment seat 4 drives the upper and lower air-permeable walls 2 to adjust outward within a range of 0 to 1.5°.

[0037] Further, refer to Figure 2-4 The direction of the arrow is the incoming flow direction.

[0038] Example 2, reference Figure 5 This embodiment describes a weak tunnel wall interference device for 1-meter-class transonic wind tunnel airfoil tests. During the airfoil test, the angle change of the upper and lower air permeable walls 2 has a negligible effect on the pressure distribution of the airfoil except for the shock wave position. Reducing the wall panel angle shifts the shock wave position rearward, while increasing the wall panel angle shifts the shock wave position forward. The position change of the ejector slot adjusting plate 8 has a negligible effect on the pressure distribution of the airfoil except for the shock wave position. Increasing the ejector slot shifts the shock wave position forward, while decreasing the ejector slot shifts the shock wave position rearward.

[0039] When the upper and lower air-permeable walls 2 are opened at an angle of 0.25° and the ejection slot adjustment piece 8 is closed, the shock wave position of the airfoil pressure distribution obtained in the experiment is completely consistent with the standard data.

[0040] Through the present invention, when conducting airfoil tests, the flow field pressure distribution of the airfoil model in the test section is basically consistent with that in the free flow, which significantly reduces the interference effect of the upper and lower hole walls and improves the flow field environment of the model; the airfoil pressure distribution test results are close to interference-free, so that the obtained airfoil pressure distribution data has a higher degree of consistency with the standard data, providing more reliable data support for the calculation of the airfoil aerodynamic force, and improving the accuracy and credibility of the test results.

[0041] The present invention can effectively alleviate the aggravated tunnel wall interference effect when the blockage degree of a conventional transonic wind tunnel increases due to the model strength requirements, thereby ensuring the effectiveness of the test under complex conditions.

[0042] Although the present invention has been described with respect to a limited number of embodiments, it will be apparent to those skilled in the art, having benefit of the foregoing description, that other embodiments are contemplated within the scope of the invention thus described. Furthermore, it should be noted that the language used in this specification has been selected primarily for readability and didactic purposes, rather than for the purpose of explaining or limiting the subject matter of the present invention. Consequently, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the present invention is intended to be illustrative rather than restrictive of the scope of the invention, which is defined by the appended claims.

Claims

1. A weak tunnel wall interference device for 1-meter-level transonic wind tunnel airfoil test, characterized in that: Includes a test section (11), a station chamber (7), an ejection slit adjustment plate (8), a wind tunnel body (9) and a motor drive rod (10); The stationary chamber (7) is provided with a test section (11) and a wind tunnel body (9), and the wind tunnel body (9) is located at the outlet side of the test section (11) in the incoming flow direction; the test section (11) includes left and right side walls (1), upper and lower air permeable walls (2), a hinge seat (3), an electric adjustment seat (4), left and right frames (5), and upper and lower frames (6); The left and right frames (5) and the upper and lower frames (6) are fixedly connected to form a rectangular frame. The left and right side walls (1) are solid walls installed on the left and right frames (5). The upper and lower air-permeable walls (2) include a first solid wall panel (21), a hole wall panel (22) and a second solid wall panel (23). The three are arranged in sequence from the inflow side to the outflow side. The first solid wall panel (21) is movably connected to the hole wall panel (22), and the hole wall panel (22) is fixedly connected to the second solid wall panel (23). The first solid wall panel (21) is fixedly connected to the hinge seat (3) on the upper and lower frames (6). The inflow side of the hole wall panel (22) is hinged to the hinge seat (3). The outflow side of the second solid wall panel (23) is connected to the electric adjustment seat (4) installed on the upper and lower frames (6). Four ejection slit adjustment pieces (8) are placed on the outside of the left and right side walls (1) and the upper and lower air-permeable walls (2), the outflow side is hinged on the wind tunnel body (9), and the inflow side is connected to the motor-driven pull rod (10) fixed on the stationary chamber (7). When the ejection slit adjustment piece (8) is closed, the ejection slit adjustment piece (8) is in contact with the outer lines of the left and right side walls (1) and the upper and lower air-permeable walls (2).

2. A weak tunnel wall interference device for 1-meter-level transonic wind tunnel airfoil test according to claim 1, characterized in that: The left and right side walls (1) are 1.2 m high, 3.8 m long and 12 mm thick.

3. A weak tunnel wall interference device for 1-meter-level transonic wind tunnel airfoil test according to claim 1, characterized in that: The upper and lower air-permeable walls (2) have a total length of 3.8 m, a width of 1.2 m, and a thickness of 12 mm; the first solid wall panel (21) of the upper and lower air-permeable walls (2) has a length of 398 mm, the perforated wall panel (22) has a length of 3190 mm, and the second solid wall panel (23) has a length of 212 mm.

4. A weak tunnel wall interference device for 1-meter-level transonic wind tunnel airfoil test according to claim 3, characterized in that: The hole wall plate (22) is provided with a vertical circular hole with a diameter of 10 mm.

5. A weak tunnel wall interference device for 1-meter-level transonic wind tunnel airfoil test according to claim 4, characterized in that: The air permeability of the upper and lower air permeable walls (2) reaches 2.8%.

6. A weak tunnel wall interference device for 1-meter-level transonic wind tunnel airfoil test according to claim 1, characterized in that: The electric adjustment seat (4) drives the upper and lower air-permeable walls (2) to adjust outwards in a range of 0 to 1.5°.

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