Smoke-wire based low speed wind tunnel flat plate model 0 degree angle of attack adjustment system and method

Abstract

A low-speed wind tunnel flat plate model 0 degree attack angle adjusting system and method based on smoke line method, the system comprises a flat plate model, a smoke line generator, a smoke silk and an image acquisition device. The present application utilizes smoke flow display technology to form smoke flow trajectory on the upper and lower surfaces of the flat plate model, analyzes the smoke flow trajectory on the upper and lower surfaces of the flat plate model by using the image acquisition device, and judges whether the flat plate model reaches the 0 degree attack angle state by whether the smoke flow trajectory on the upper and lower surfaces of the flat plate model is symmetrically distributed; an arc surface is arranged on the leading edge of the flat plate model to form symmetric flow around; a fairing cone surface is arranged on the trailing edge of the flat plate model to reduce the disturbance of the wake flow to the overall flow field of the flat plate model, so that the flow around the leading edge of the flat plate model is closer to the ideal working condition, the reliability of 0 degree attack angle determination is improved, and the measurement accuracy is significantly improved; the whole process does not need complex flow field measuring equipment, and has the remarkable characteristics of low cost, simple operation and easy engineering.

Description

Technical Field

[0001] This invention belongs to the field of wind tunnel testing technology, and in particular relates to a system and method for adjusting the 0-degree angle of attack of a low-speed wind tunnel flat plate model based on the smoke line method. Background Technology

[0002] In low-speed wind tunnel tests, the flat plate model is widely used in the study of fundamental fluid mechanics problems such as boundary layer flow, transition, separation, and turbulence characteristics. The accuracy of the angle of attack of the flat plate model relative to the incoming flow is one of the key factors that determine the reliability of wind tunnel test data.

[0003] However, in engineering practice, the poor observability caused by the transparency of air makes it difficult to precisely adjust the flat plate model to a 0-degree angle of attack relative to the incoming flow. Furthermore, since installation errors of the flat plate model cannot be completely avoided in wind tunnel flow fields, it is often difficult to guarantee a strictly 0-degree angle of attack in actual wind tunnel tests.

[0004] In conventional wind tunnel tests, both theory and practice have shown that even a small deviation in the angle of attack can significantly affect the surface pressure distribution, friction drag coefficient, boundary layer development, and transition position of a flat plate model, leading to deviations in experimental data, affecting the correct understanding of the flow physics mechanism, and reducing the reliability of numerical simulation verification.

[0005] Currently, even in the most precise wind tunnels, the angle of attack deviation |Δ α It can only meet the requirement of ≤0.1°. In studies on the frictional resistance, boundary layer transition, and wall shear stress of the plate model, which are extremely sensitive to the angle of attack, even a deviation of 0.1° is enough to cause an asymmetric change in the surface pressure distribution of the plate model, thereby causing the measurement results to deviate from the actual physical conditions and seriously affecting the accuracy of the experimental conclusions. Summary of the Invention

[0006] To address the problems of existing technologies, this invention provides a 0-degree angle-of-attack adjustment system and method for a low-speed wind tunnel flat plate model based on the smoke line method. Utilizing smoke line flow display technology, smoke flow trajectories are formed on the upper and lower surfaces of the flat plate model. Image acquisition equipment is used to analyze these smoke flow trajectories on the upper and lower surfaces of the flat plate model. Whether the smoke flow trajectories on the upper and lower surfaces of the flat plate model are symmetrically distributed determines whether the flat plate model has reached the 0-degree angle-of-attack state. An arc-shaped surface is set at the leading edge of the flat plate model to form symmetrical flow around the incoming flow. A flow-rectifying cone surface is set at the trailing edge of the flat plate model to reduce the disturbance of the wake flow on the overall flow field of the flat plate model, making the flow around the leading edge of the flat plate model closer to the ideal working condition, improving the reliability of the 0-degree angle-of-attack determination, and significantly improving measurement accuracy. The entire process requires no complex flow field measurement equipment and has significant advantages such as low cost, simple operation, and ease of engineering application.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a 0-degree angle of attack adjustment system for a low-speed wind tunnel flat plate model based on the smoke line method, comprising a flat plate model, a smoke line generator, a smoke filament, and an image acquisition device; the flat plate model is disposed inside the wind tunnel; the smoke line generator is disposed outside the wind tunnel; the smoke filament is vertically fixed inside the wind tunnel, located directly in front of the leading edge of the flat plate model, and the smoke filament is electrically connected to the smoke line generator via a wire; the image acquisition device is horizontally fixed to the side of the flat plate model, and the central axis of the lens of the image acquisition device is perpendicular to the central axis of the wind tunnel.

[0008] The center point of the smoke filament is aligned with the center point of the leading edge of the flat plate model along the central axis of the wind tunnel.

[0009] An arc-shaped surface is provided at the leading edge of the flat plate model.

[0010] A flow-rectifying cone surface is provided at the trailing edge of the flat plate model.

[0011] The thickness of the flat plate model is 10mm to 20mm.

[0012] The smoking filament is made of a single metal wire, and a smoking agent is coated on the surface of the smoking filament.

[0013] The diameter of the smoking shreds is 0.1 mm to 0.3 mm.

[0014] The length of the smoking filament is 400mm to 1000mm.

[0015] The distance between the smoking filament and the leading edge of the flat plate model is 50mm to 200mm.

[0016] A method for adjusting the 0-degree angle of attack of a low-speed wind tunnel flat plate model based on the smoke line method, employing the aforementioned low-speed wind tunnel flat plate model 0-degree angle of attack adjustment system based on the smoke line method, includes the following steps: Step 1: Install the flat plate model inside the wind tunnel test section; Step 2: Install the smoke generator into the wind tunnel test section and connect the smoke generator to the smoke wire generator with a wire; Step 3: Start the wind tunnel and adjust the wind speed to the initial set value; Step 4: After the wind field in the wind tunnel stabilizes, start the smoke generator to heat the smoke filaments. The smoke-generating agent on the surface of the smoke filaments will generate continuous smoke veins when heated. Step 5: Start the image acquisition device to obtain real-time flow field distribution images of the flat plate model and the smoke trajectory; Step 6: Analyze the real-time flow field distribution image. When the smoke trails on the upper and lower surfaces of the flat plate model are symmetrically distributed, the angle of attack of the flat plate model is determined to be 0 degrees. If the smoke trails on the upper and lower surfaces of the flat plate model are not symmetrically distributed, the angle of attack of the flat plate model is determined to be less than 0 degrees. Then continue to adjust the attitude of the flat plate model until the smoke trails on the upper and lower surfaces of the flat plate model are symmetrically distributed. Step 7: Using the angle of attack of the flat plate model as 0 degrees as a basis, conduct subsequent wind tunnel tests; Step 8: Change the wind speed inside the wind tunnel and repeat steps 4 to 7 to conduct wind tunnel tests at different wind speeds.

[0017] The beneficial effects of this invention are: This invention relates to a low-speed wind tunnel flat plate model 0-degree angle of attack adjustment system and method based on the smoke line method. It utilizes smoke line flow display technology to form smoke flow trajectories on the upper and lower surfaces of the flat plate model. Image acquisition equipment is used to analyze these trajectories, and the symmetry of the smoke flow trajectories on the upper and lower surfaces determines whether the flat plate model has reached a 0-degree angle of attack. An arc-shaped surface is provided at the leading edge of the flat plate model to create symmetrical flow around the incoming flow. A flow-rectifying cone is provided at the trailing edge of the flat plate model to reduce the disturbance of the wake flow on the overall flow field of the flat plate model, making the flow around the leading edge of the flat plate model closer to the ideal operating condition, improving the reliability of the 0-degree angle of attack determination, and significantly improving measurement accuracy. The entire process requires no complex flow field measurement equipment and has significant advantages such as low cost, simple operation, and ease of engineering. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a 0-degree angle of attack adjustment system for a low-speed wind tunnel flat plate model based on the smoke line method according to the present invention. In the figure, 1—flat plate model, 2—smoke generator, 3—smoke filament, 4—image acquisition device, 5—wire, 6—arc-shaped surface, 7—rectifier cone surface. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0020] like Figure 1 As shown, a low-speed wind tunnel flat plate model 0-degree angle of attack adjustment system based on the smoke line method includes a flat plate model 1, a smoke line generator 2, a smoke filament 3, and an image acquisition device 4. The flat plate model 1 is set inside the wind tunnel; the smoke line generator 2 is set outside the wind tunnel; the smoke filament 3 is vertically fixed inside the wind tunnel, located directly in front of the leading edge of the flat plate model 1, and is electrically connected to the smoke line generator 2 through a wire 5; the image acquisition device 4 is horizontally fixed to the side of the flat plate model 1, and the central axis of the lens of the image acquisition device 4 is perpendicular to the central axis of the wind tunnel.

[0021] The center point of the smoke filament 3 is aligned with the center point of the leading edge of the flat plate model 1 along the central axis of the wind tunnel.

[0022] An arc-shaped surface 6 is provided at the leading edge of the flat plate model 1.

[0023] A rectifying cone surface 7 is provided at the trailing edge of the flat plate model 1.

[0024] The thickness of the flat plate model 1 is 10mm to 20mm.

[0025] The smoking filament 3 is made of a single metal wire, and a smoking agent is coated on the surface of the smoking filament 3.

[0026] The diameter of the tobacco filament 3 is 0.1 mm to 0.3 mm.

[0027] The length of the tobacco filament 3 is 400mm to 1000mm.

[0028] The distance between the smoking filament 3 and the front edge of the flat plate model 1 is 50mm to 200mm.

[0029] A method for adjusting the 0-degree angle of attack of a low-speed wind tunnel flat plate model based on the smoke line method, employing the aforementioned low-speed wind tunnel flat plate model 0-degree angle of attack adjustment system based on the smoke line method, includes the following steps: Step 1: Install the flat plate model 1 inside the wind tunnel test section; Step 2: Install the smoke generator 3 into the wind tunnel test section, and connect the smoke generator 3 to the smoke generator 2 through the wire 5; Step 3: Start the wind tunnel and adjust the wind speed to the initial set value; Step 4: After the wind field in the wind tunnel stabilizes, start the smoke generator 2 to heat the smoke filament 3. The smoke-generating agent on the surface of the smoke filament 3 will generate continuous smoke pulses when heated. Step 5: Start the image acquisition device 4 to acquire real-time flow field distribution images of the flat plate model 1 and the smoke trajectory; Step 6: Analyze the real-time flow field distribution image. When the smoke trajectory on the upper and lower surfaces of the plate model 1 is symmetrically distributed, the angle of attack of the plate model 1 is determined to be 0 degrees. If the smoke trajectory on the upper and lower surfaces of the plate model 1 is not symmetrically distributed, the angle of attack of the plate model 1 is determined to be less than 0 degrees. Then continue to adjust the attitude of the plate model 1 until the smoke trajectory on the upper and lower surfaces of the plate model 1 is symmetrically distributed. Step 7: Based on the angle of attack of flat plate model 1 being 0 degrees, conduct subsequent wind tunnel tests; Step 8: Change the wind speed inside the wind tunnel and repeat steps 4 to 7 to conduct wind tunnel tests at different wind speeds.

[0030] The solutions described in the embodiments are not intended to limit the scope of protection of the present invention. All equivalent implementations or modifications that do not depart from the present invention are included within the scope of protection of the present invention.

Claims

1. A 0-degree angle-of-attack adjustment system for a low-speed wind tunnel flat plate model based on the smoke line method, characterized in that: The system includes a flat panel model, a smoke generator, a smoke filament, and an image acquisition device. The flat panel model is installed inside the wind tunnel. The smoke generator is installed outside the wind tunnel. The smoke filament is vertically fixed inside the wind tunnel, located directly in front of the leading edge of the flat panel model, and is electrically connected to the smoke generator via a wire. The image acquisition device is horizontally fixed to the side of the flat panel model, with the central axis of the image acquisition device's lens perpendicular to the central axis of the wind tunnel.

2. The 0-degree angle of attack adjustment system for a low-speed wind tunnel flat plate model based on the smoke line method according to claim 1, characterized in that: The center point of the smoke filament is aligned with the center point of the leading edge of the flat plate model along the central axis of the wind tunnel.

3. The 0-degree angle of attack adjustment system for a low-speed wind tunnel flat plate model based on the smoke line method according to claim 1, characterized in that: An arc-shaped surface is provided at the leading edge of the flat plate model.

4. The 0-degree angle of attack adjustment system for a low-speed wind tunnel flat plate model based on the smoke line method according to claim 1, characterized in that: A flow-rectifying cone surface is provided at the trailing edge of the flat plate model.

5. The 0-degree angle of attack adjustment system for a low-speed wind tunnel flat plate model based on the smoke line method according to claim 1, characterized in that: The thickness of the flat plate model is 10mm to 20mm.

6. The 0-degree angle of attack adjustment system for a low-speed wind tunnel flat plate model based on the smoke line method according to claim 1, characterized in that: The smoking filament is made of a single metal wire, and a smoking agent is coated on the surface of the smoking filament.

7. The 0-degree angle of attack adjustment system for a low-speed wind tunnel flat plate model based on the smoke line method according to claim 1, characterized in that: The diameter of the smoking shreds is 0.1 mm to 0.3 mm.

8. The 0-degree angle of attack adjustment system for a low-speed wind tunnel flat plate model based on the smoke line method according to claim 1, characterized in that: The length of the smoking filament is 400mm to 1000mm.

9. The 0-degree angle of attack adjustment system for a low-speed wind tunnel flat plate model based on the smoke line method according to claim 1, characterized in that: The distance between the smoking filament and the leading edge of the flat plate model is 50mm to 200mm.

10. A method for adjusting the 0-degree angle of attack of a low-speed wind tunnel flat plate model based on the smoke line method, comprising the low-speed wind tunnel flat plate model 0-degree angle of attack adjustment system based on the smoke line method as described in claim 1, characterized in that, Includes the following steps: Step 1: Install the flat plate model inside the wind tunnel test section; Step 2: Install the smoke generator into the wind tunnel test section and connect the smoke generator to the smoke wire generator with a wire; Step 3: Start the wind tunnel and adjust the wind speed to the initial set value; Step 4: After the wind field in the wind tunnel stabilizes, start the smoke generator to heat the smoke filaments. The smoke-generating agent on the surface of the smoke filaments will generate continuous smoke veins when heated. Step 5: Start the image acquisition device to obtain real-time flow field distribution images of the flat plate model and the smoke trajectory; Step 6: Analyze the real-time flow field distribution image. When the smoke trails on the upper and lower surfaces of the flat plate model are symmetrically distributed, the angle of attack of the flat plate model is determined to be 0 degrees. If the smoke trails on the upper and lower surfaces of the flat plate model are not symmetrically distributed, the angle of attack of the flat plate model is determined to be less than 0 degrees. Then continue to adjust the attitude of the flat plate model until the smoke trails on the upper and lower surfaces of the flat plate model are symmetrically distributed. Step 7: Using the angle of attack of the flat plate model as 0 degrees as a basis, conduct subsequent wind tunnel tests; Step 8: Change the wind speed inside the wind tunnel and repeat steps 4 to 7 to conduct wind tunnel tests at different wind speeds.

Images