A Martian wind tunnel with sand and dust simulation

Abstract

The purpose of the present invention is to provide a Mars wind tunnel with sand and dust simulation, which is horizontally placed in a vacuum container, including a collector, a stabilizing section, a contraction section, a test section, an ejector section, an outlet diffusion section and an ejector, and also includes a first diffusion section, the test section is connected to the first diffusion section, the first diffusion section is connected to the ejector section, the ejector section is connected to the diffusion section, there is a transitional straight section between the ejector section and the diffusion section, the ejector section is installed at the inlet of the ejector section, the diffusion angle of the first diffusion section does not exceed 5°, and the inlet cross-sectional area of ​​the ejector section is larger than the outlet cross-sectional area of ​​the test section. Only a small amount of gas is consumed to achieve a large-span wind speed simulation of 5-100m / s at an air pressure of 100Pa, and the flow field of the test section is uniform and stable, and the sand and dust environment of Mars can be simulated at this low air pressure.

Description

Technical Field

[0001] The invention relates to a Martian wind tunnel with sand and dust simulation. Background Art

[0002] Wind tunnels are generally used to study the aerodynamic performance of aircraft and related designs. Conventional wind tunnels are developed for aircraft designed to fly in the surface atmosphere. The Mars wind tunnel is a test simulation device developed for the atmospheric flight environment of Mars. Unlike conventional wind tunnels, the Mars wind tunnel can simulate the gas composition, atmospheric pressure, density and flow field environment on the surface of Mars. The atmosphere of Mars is very thin. The main component of the atmosphere is carbon dioxide. The atmospheric density is about 1% of that of the Earth (similar to the density at an altitude of 30-40km on the Earth's surface). The average surface pressure of Mars is only 600Pa. Local or regional sandstorms on Mars can occur frequently in different seasons and different places on Mars. Due to the large difference in the atmospheric environment between the surface of Mars and the surface of the Earth, conventional atmospheric environment wind tunnels cannot meet the needs of further simulating the atmospheric environment of Mars. Conventional DC wind tunnels usually use motors or ejectors as the driving source. When using motors as the driving source, it is impossible to form the wind speed required for Mars simulation tests in a low-pressure environment. When using ordinary ejectors as the driving source, the ejected airflow is prone to saturation blockage at the outlet, and it is also impossible to achieve high wind speed simulation in a low-pressure environment. In addition, conventional sand and dust simulation is also difficult to maintain a high consistency with the wind speed in a low-pressure environment, and it is even more difficult to ensure the uniformity of sand and dust distribution in the test section. Therefore, in order to meet the needs of experimental research related to deep space exploration and the Martian environment, it is necessary to carry out research on Martian wind tunnels, and a Martian wind tunnel that can simulate the Martian dust environment is needed. Summary of the invention

[0003] Based on the above shortcomings, the purpose of the present invention is to provide a Martian wind tunnel with sand and dust simulation. The wind tunnel is horizontally placed in a low-pressure vacuum container. It only consumes a small amount of gas and can achieve a large-span wind speed simulation of 5-100m / s under an air pressure of 100Pa. The flow field of the test section is uniform and stable, and it can simulate the sand and dust environment of Mars under this low pressure.

[0004] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme to achieve it: a Mars wind tunnel with sand and dust simulation, which is placed horizontally in a vacuum container and adopts the structure of a direct current wind tunnel, including a collector, a stabilizing section, a contraction section, a test section, an ejector section, an outlet diffuser section and an ejector, the collector is connected to the stabilizing section, the stabilizing section is connected to the contraction section, the contraction section is connected to the test section, the wind tunnel also includes a first diffuser section, the test section is connected to the first diffuser section, the first diffuser section is connected to the ejector section, the ejector section is connected to the diffuser section, and there is a transitional straight section between the ejector section and the diffuser section, an ejector is installed at the inlet of the ejector section, the first diffuser section diffuses at a certain angle, the diffusion angle does not exceed 5°, the inlet cross-sectional area of ​​the ejector section is larger than the outlet cross-sectional area of ​​the test section, and the area ratio is more than 3 times. A first diffuser section is set between the test section and the ejector section to form a high cross-sectional area ratio between the ejector section and the test section, which helps to improve the efficiency of the ejector and avoid the problem of blockage of the airflow in the ejector due to low air pressure, which results in the wind speed being unable to be further increased, thereby increasing the upper limit of the wind speed in the wind tunnel.

[0005] The present invention also has the following technical features:

[0006] 1. A sand and dust nozzle is detachably connected to the interior of the contraction section. The height of the sand and dust nozzle coincides with the center line of the wind tunnel and is arranged in the opposite direction of the airflow. The sand and dust nozzle is far away from the entrance of the test section.

[0007] 2. The cross-sectional area of ​​the outlet of the test section is larger than the cross-sectional area of ​​the inlet. The inlet of the test section is square, and the upper and lower walls diffuse at a certain angle along the airflow direction. The outlet of the test section is rectangular, and its width is the same as the width of the inlet of the test section, but its height is larger than the inlet of the test section. By changing the diffusion angle set on the upper and lower walls of the test section to make the outlet of the test section larger than the inlet area, the boundary layer blocking effect of the wind tunnel test section can be significantly improved.

[0008] 3. The ejector comprises an ejector chamber shell, a plurality of ejector nozzles and an ejector connecting air pipe. The ejector chamber shell surrounds the outer wall of the ejector section and is sealed and connected to the outer wall of the ejector section to form a closed ejector chamber. The plurality of ejector nozzles are located in the ejector chamber and are parallel to each other and radially pass through the ejector section at a certain interval. The head and tail of each nozzle are respectively connected to the ejector chamber. The ejector nozzle portion located in the ejector section is provided with a plurality of trumpet-shaped small holes, and the small holes are symmetrically arranged in a square array.

[0009] 4. A test section gate is provided on one side of the test section. An observation window is provided on the gate and a mechanical handwheel is provided. An observation window is also provided on the top of the test section. The pitot tube for measuring wind speed and the dust concentration meter for measuring sand and dust concentration can be detachably installed on the upper wall of the test section. The pitot tube can measure wind speed and the gas pressure of the test section at the same time. The gate provided on one side of the test section can be quickly opened and closed by a mechanical handwheel. A support and a balance force measuring device are installed on the wall of the wind tunnel on the other side of the test section, which can realize the clamping and force measurement of the test piece during the test. In addition, through the observation windows on the top of the test section and the gate of the test section, the whole test process can be observed, or related tests such as PIV (particle image velocimetry) can be carried out.

[0010] Advantages and beneficial effects of the present invention: This wind tunnel is different from the traditional DC wind tunnel. It is driven by an ejector instead of a motor. It can ensure that under extremely low ambient pressure, a large-span test wind speed is formed in the test section while consuming very little gas flow. This wind tunnel is placed horizontally in a low-pressure vacuum container. By adjusting the pressure in the container, the pressure environment in the range of 100-1500Pa is simulated. Under this pressure environment, a large-span wind speed range of 5-100m / s can be simulated, and the wind speed can be continuously adjusted. By arranging a sand and dust injection device in the contraction section, a sand and dust simulation with a sand and dust particle size of 1-100μm at a certain wind speed under a low-pressure environment can be achieved, and the concentration range can reach 0.1-1g / m 3 , and the concentration can be continuously adjusted. The test gas medium of the Mars wind tunnel can be either air or gaseous carbon dioxide. The structure of the direct current wind tunnel is adopted, and the sand and dust injection is not easy to form backflow. The sand and dust are injected by reverse airflow. The sand and dust in the test section are evenly distributed, and the nozzle will not interfere with the flow field of the test section. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is the main view of a Martian wind tunnel with sand and dust simulation.

[0012] Figure 2 This is a left view of a Martian wind tunnel with sand and dust simulation.

[0013] Figure 3 yes Figure 2 Cross-sectional view of AA in .

[0014] In the figure: 1. collector, 2. stabilizing section, 3. contraction section, 4. test section, 5. first diffusion section, 6. ejector section, 6-1. straight section, 7. outlet diffusion section, 8. ejector, 8-1. ejector chamber shell, 8-2. ejector chamber, 9. ejector nozzle, 10. ejector connecting air pipe, 11. sand and dust nozzle, 12. sand and dust conveying pipeline, 13. connecting bolts, 14. outlet diffusion section flange, 15. test section door, 16. observation window, 17. connecting flange, 18. mechanical handwheel. DETAILED DESCRIPTION

[0015] The present invention will be further described below with reference to the accompanying drawings and examples.

[0016] Example 1

[0017] A Mars wind tunnel with sand and dust simulation, the wind tunnel is horizontally placed in a low-pressure vacuum container, adopts the structure of a direct-current wind tunnel, includes a collector 1, a stabilizing section 2, a contraction section 3, a test section 4, an ejector section 6, an outlet diffusion section 7 and an ejector 8, the collector 1 is in a trumpet shape, the collector 1 is connected to the inlet of the stabilizing section 2, the cross section of the stabilizing section 2 is square, a layer of honeycomb and a multi-layer damping net connection port are reserved inside, the honeycomb and the damping net are optional parts, and can be installed according to the needs of the test, the outlet of the stabilizing section 2 is connected to the inlet of the contraction section 3 through a flange, the outlet of the contraction section 3 is connected to the inlet of the test section 4 The outlet of the test section 4 is connected with the inlet of the first diffuser section 5 through a flange. The outlet of the first diffuser section 5 is connected with the inlet of the ejector section 6 through a flange. The outlet of the ejector section 6 is connected with the inlet of the diffuser section 7 through a flange. There is a transitional straight section 6-1 between the ejector section 6 and the outlet diffuser. An ejector is installed at the inlet of the ejector section 6. The first diffuser section 5 diffuses at a certain angle, and the diffusion angle does not exceed 5°. The inlet cross-sectional area of ​​the ejector section 6 is larger than the outlet cross-sectional area of ​​the test section 4, and the area ratio is more than 3 times. During the test, the wind tunnel is located in a vacuum container, which can provide the Mars wind tunnel with the air pressure required for the test (100-1500Pa). The gas required for the test enters the ejector chamber 8-1 through the ejector connecting air pipe 10, and is then quickly ejected through the small holes on the ejector nozzle 9. The gas forms suction in the form of rapid expansion, which can suck the airflow outside the wind tunnel from the wind tunnel entrance, pass through the test section, and then be discharged from the outlet diffusion section.

[0018] The interior of the contraction section 3 is detachably connected with a sand and dust nozzle 11, the height of which coincides with the center line of the wind tunnel, and is arranged in the opposite direction of the airflow. The sand and dust nozzle is away from the entrance of the test section 4, and the sand and dust nozzle 11 can be installed in reverse or forward direction.

[0019] A test section gate 15 is provided on one side of the test section 4, an observation window 16 is provided on the test section gate 15, and a mechanical hand wheel 18 is provided. A support and a balance force measuring device are installed on the wind tunnel wall on the other side of the test section 4. An observation window 16 is also provided on the top of the test section 4. A Pitot tube for measuring wind speed and a dust concentration meter for measuring sand and dust concentration are detachably installed on the upper wall of the test section 4.

[0020] The outlet cross-sectional area of ​​the test section is larger than the inlet cross-sectional area of ​​the test section. The inlet of the test section is square and diffuses at a small angle along the upper and lower walls in the direction of airflow. The outlet of the test section is rectangular and has the same width as that of the inlet of the test section, but a height greater than that of the inlet of the test section.

[0021] The ejector 8 comprises an ejector chamber shell 8-1, a plurality of ejector nozzles 9 and an ejector connecting air pipe 10. The ejector chamber shell 8-1 surrounds the outer wall of the ejector section 6 and is sealed and connected to the outer wall of the ejector section to form a closed ejector chamber 8-2. The plurality of ejector nozzles 9 are located in the ejector chamber 8 and are parallel to each other and radially pass through the ejector section 6 at a certain interval. The head and tail of each nozzle 9 are respectively connected to the ejector chamber 8-2. The ejector chamber 8 is connected to the ejector connecting air pipe 10. The ejector nozzle 9 is located in the ejector section 6. The part is provided with a plurality of trumpet-shaped small holes with narrow throat diameters. The small holes are symmetrically arranged in a square array.

[0022] Example 2

[0023] This embodiment adopts the structure of embodiment 1, and adjusts the air supply flow entering the ejector chamber 8 through a high-precision regulating valve, thereby changing the injection flow of the ejector and further changing the wind speed in the test section. Nine ejector nozzles 9 are arranged in parallel at equal intervals, and each nozzle has nine injection holes, for a total of 81 holes.

[0024] Example 3

[0025] This embodiment adopts the structure of embodiment 1. When conducting a sand and dust simulation test, a pressure-feeding method is used to convey sand and dust, so that a relatively high-pressure test gas enters the sand and dust conveying pipeline 12 and mixes with the sand and dust for conveying, passes through a venturi ejector, and is finally ejected from the sand and dust nozzle 11 of the contraction section. In order to make the sand and dust in the test section 4 disperse evenly, the outlet structure of the sand and dust nozzle 11 adopts a multi-layer staggered form, and adopts a reverse airflow injection direction. This method can also keep the nozzle away from the entrance of the test section, thereby improving the flow field quality of the test section. When it is not necessary to simulate a sand and dust test, the sand and dust nozzle and its pipeline can be removed, and the dust concentration meter can be removed at the same time to further improve the flow field quality of the test section. When the sand blowing test is carried out by spraying in a reverse airflow manner, the wind speed of the test section 4 needs to be above 32.5m / s. When the wind speed is lower than 32.5m / s and sand blowing is still required, the sand and dust nozzle 11 can be installed in a forward direction.

[0026] Example 4

[0027] This embodiment adopts the structure of embodiment 1. In order to enable the test section 4 to reach a wind speed of more than 100m / s under extremely low air pressure, the ejector section 6 is connected to the test section 4 through the first diffuser section 5. The diffusion angle of the first diffuser section 5 is about 4.6°. The ratio of the inlet area of ​​the ejector section 6 to the outlet area of ​​the test section 4 is 4 times, which can significantly improve the ejector efficiency and avoid the problem that the wind speed cannot be further increased due to the blockage of the air flow of the ejector caused by low air pressure. The airflow ejected by the ejector of the ejector section 6 is mixed with the airflow discharged from the test section 4 and then discharged through the outlet diffuser section 7. The diffusion angle of the outlet diffuser section 7 is 5°.

[0028] Example 5

[0029] This embodiment adopts the structure of embodiment 1, and the contraction ratio of the wind tunnel (the ratio of the cross-sectional area of ​​the outlet of the stable section 2 to the cross-sectional area of ​​the inlet of the test section 4) is selected as 12. A higher contraction ratio can reduce the longitudinal turbulence effect of the test section 4. According to the test needs, the honeycomb and damping net reserved in the stable section 2 can be installed to further reduce the turbulence of the test section 4.

[0030] The inlet cross-sectional dimensions of test section 4 are 210 mm wide × 210 mm high, the upper and lower wall diffusion angles are 0.5 degrees, and the outlet cross-sectional dimensions of test section 4 are 210 mm wide × 218 mm high. The increase in the outlet cross-sectional area of ​​test section 4 can improve the boundary layer blocking effect of wind tunnel test section 4.

Claims

1. A Mars wind tunnel with sand and dust simulation, the wind tunnel is horizontally placed in a vacuum container, adopts the structure of a direct current wind tunnel, comprises a collector (1), a stabilizing section (2), a contraction section (3), a test section (4), an ejector section (6), an outlet diffuser section (7) and an ejector (8), the collector (1) is connected to the stabilizing section (2), the stabilizing section (2) is connected to the contraction section (3), the contraction section (3) is connected to the test section (4), and is characterized in that: It also includes a first diffusion section (5), the test section (4) is connected to the first diffusion section (5), the first diffusion section (5) is connected to the ejector section (6), the ejector section (6) is connected to the diffusion section (7), there is a transitional straight section (6-1) between the ejector section (6) and the diffusion section (7), the inlet of the ejector section (6) is equipped with an ejector, the first diffusion section (5) diffuses at a certain angle, the diffusion angle does not exceed 5°, the inlet cross-sectional area of ​​the ejector section (6) is larger than the outlet cross-sectional area of ​​the test section (4), and the area ratio is more than 3 times; the interior of the contraction section (3) is detachably connected to a sand and dust nozzle (11), the height of the sand and dust nozzle (11) coincides with the center line of the wind tunnel, and is arranged in the opposite direction of the airflow, and the sand and dust nozzle is away from the test section. (4) entrance; the ejector (8) comprises an ejector chamber shell (8-1), a plurality of ejector nozzles (9) and an ejector connecting air pipe (10); the ejector chamber shell (8-1) surrounds the outer wall of the ejector section (6) and is sealed and connected to the outer wall of the ejector section to form a closed ejector chamber (8-2); the plurality of ejector nozzles (9) are located in the ejector chamber (8-2) and are parallel to each other and radially pass through the ejector section (6) at a certain interval; the head and tail of each nozzle (9) are respectively connected to the ejector chamber (8-2); the ejector chamber (8-2) is connected to the ejector connecting air pipe (10); the ejector nozzle (9) is provided with a plurality of trumpet-shaped small holes in the portion located in the ejector section (6); the small holes are symmetrically arranged in a square array.

2. A Mars wind tunnel with sand and dust simulation according to claim 1, characterized in that: The outlet cross-sectional area of ​​the test section (4) is larger than the inlet cross-sectional area. The inlet of the test section (4) is square and diffuses at a certain angle along the upper and lower walls of the airflow direction. The outlet of the test section (4) is rectangular and has the same width as the inlet of the test section (4), but a height greater than the inlet of the test section (4).

3. A Martian wind tunnel with sand and dust simulation according to claim 1 or 2, characterized in that: A test section door (15) is provided on one side of the test section (4), an observation window (16) is provided on the test section door (15), and a mechanical hand wheel (18) is provided. A support and a balance force measuring device are installed on the wind tunnel wall on the other side of the test section (4). An observation window (16) is also provided on the top of the test section (4). A pitot tube for measuring wind speed and a dust concentration meter for measuring sand and dust concentration are detachably installed on the upper wall of the test section (4).

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