Sealed low-temperature and low-pressure wind tunnel

Abstract

The invention discloses a sealed low-temperature and low-pressure wind tunnel which comprises a wind tunnel unit which is of a backflow type closed circuit structure, a power section is provided with a driving part for driving gas to flow and a first rectifying mechanism for adjusting rotating airflow generated by the driving part into direct-current airflow, and a rectifying and flow stabilizing section is provided with a second rectifying mechanism for reducing airflow turbulence. At least one temperature measuring component, at least one pressure measuring component and at least one wind speed measuring component are arranged in the wind tunnel unit; the refrigeration unit is used for cooling gas in the wind tunnel unit and comprises a heat exchange mechanism and a refrigerator connected with the heat exchange mechanism; the pressure maintaining unit is used for maintaining the pressure of the gas in the wind tunnel unit; the temperature measuring component, the pressure measuring component, the wind speed measuring component, the driving component, the refrigeration circulator, the vacuum pump and the three-way valve are in signal connection with the control unit. The sealed low-temperature and low-pressure wind tunnel provided by the invention can simulate typical low-pressure, low-temperature and low-wind-speed conditions of a stratosphere.

Description

Technical Field

[0001] This invention relates to the field of low-temperature simulation experiment technology, and in particular to a sealed low-temperature and low-pressure wind tunnel. Background Technology

[0002] Wind tunnels are ground-based infrastructure for aerodynamic research, used to artificially generate and precisely control airflow to simulate aerodynamic phenomena in real-world environments. With breakthroughs in in-situ wind measurement technology for near-space floating platforms (high-altitude balloons, high-altitude airships), there is an urgent need for testing and calibration in their operating range—the low-pressure, low-temperature stratosphere. However, traditional technical approaches present significant contradictions in this scenario: large-scale cryogenic wind tunnels or environmental chamber systems, while capable of reproducing the stratospheric environment, are bulky and expensive; while low-cost, easy-to-operate micro-wind tunnels lack the ability to simulate low pressure and low temperatures. More importantly, maintaining a low-turbulence, high-stability, and uniformly low-velocity flow field for extended periods in a confined, low-pressure space is technically extremely challenging, placing special demands on power units, flow channel design, and control systems. Therefore, there is an urgent need in this field for an integrated, miniaturized, dedicated solution to fill the gap in high-precision calibration equipment for the stratospheric environment. Summary of the Invention

[0003] Based on the above problems, the purpose of this invention is to provide a sealed low-temperature and low-pressure wind tunnel that can stably, controllably, and effectively simulate the typical low-pressure, low-temperature, and low-wind-speed conditions of the stratosphere.

[0004] To overcome the shortcomings of the prior art, the technical solution provided by this invention is as follows:

[0005] A sealed low-temperature, low-pressure wind tunnel, comprising:

[0006] The wind tunnel unit is a closed-loop recirculation structure, comprising a power section, a rectification and stabilization section, a contraction section, a test section, a diffusion section, and a recirculation guide section connected in sequence. The power section is equipped with a driving component that drives the gas flow and a first rectification mechanism that adjusts the rotating airflow generated by the driving component into a direct current airflow. The rectification and stabilization section is equipped with a second rectification mechanism that reduces the turbulence of the airflow. The wind tunnel unit is equipped with at least one temperature measuring component, at least one pressure measuring component, and at least one wind speed measuring component.

[0007] A refrigeration unit, used to cool the gas inside the wind tunnel unit, includes a heat exchange mechanism and a refrigerator connected to the heat exchange mechanism;

[0008] The pressure holding unit is used to maintain the pressure of the gas in the wind tunnel unit. It includes a ventilation pipe connected to the wind tunnel unit at one end, an inlet and outlet valves provided on the ventilation pipe, a vacuum pump connected to the other end of the ventilation pipe, an inlet pipe connected to the section of the ventilation pipe located between the inlet and outlet valves and the vacuum pump, and a three-way valve provided between the inlet pipe and the ventilation pipe.

[0009] The control unit, including the temperature measuring component, pressure measuring component, wind speed measuring component, drive component, refrigeration circulator, vacuum pump, and three-way valve, is connected to the control unit via signals.

[0010] In one embodiment, the wind tunnel unit includes a wind tunnel body and return pipes connected to the wind tunnel body at both ends. The portion of the return pipe near the air inlet of the wind tunnel body forms the power section. The rectification and stabilization section is located inside the wind tunnel body, and the contraction section is formed at the air outlet. The test section is located downstream of the contraction section inside the wind tunnel body. The diffusion section is located downstream of the test section inside the wind tunnel body. The portion of the return pipe near the air outlet of the wind tunnel body forms the return flow guiding section.

[0011] In one embodiment, the first rectification mechanism includes a support frame mounted on the inner wall of the return pipe and located downstream of the drive component, and a first rectification sleeve fixed to the support frame, the first rectification sleeve extending axially along the return pipe of the power section.

[0012] In one embodiment, the first rectifying sleeve includes a mounting portion coaxially arranged with the return pipe of the power section and a rectifying portion connected to the mounting portion. The rectifying portion is conical and tapers along the airflow direction. The support frame includes a plurality of connecting plates connecting the mounting portion and the inner wall of the return pipe.

[0013] In one embodiment, the second rectification mechanism includes a second rectification sleeve installed in the wind tunnel body and a flow stabilizing component installed in the second rectification sleeve. The flow stabilizing component includes a honeycomb rectifier installed on the inner wall of the second rectification sleeve and at least one layer of damping mesh arranged on the honeycomb rectifier.

[0014] In one embodiment, the second rectifier sleeve includes a first rectifier section and a second rectifier section that are detachably connected. The first rectifier section includes a connecting section connected to the return pipe, a flow stabilizing section, and a gradually expanding section connecting the connecting section and the flow stabilizing section. The second rectifier section includes a gradually contracting section extending in the airflow direction and an output section connected to the gradually contracting section. The rectifier assembly is installed at one end of the first rectifier section near the second rectifier section.

[0015] In one embodiment, the test section is provided with a support for fixing the sample, and a transparent observation window is detachably provided on the outer wall of the wind tunnel body at a position corresponding to the support.

[0016] In one embodiment, a fixed flange is provided on the outer wall of the wind tunnel body, and the transparent observation window is detachably connected to the fixed flange.

[0017] In one embodiment, the heat exchange mechanism includes a heat exchange coil installed inside the wind tunnel body, and a heat exchange fan is installed inside the wind tunnel body.

[0018] In one embodiment, an insulation layer is fixed to the outer wall of the wind tunnel unit.

[0019] Compared with the prior art, the advantages of the present invention are:

[0020] 1. It adopts a closed-loop recirculation compact structure, and the main body is made of low-cost general-purpose materials such as stainless steel 304. The cost is low and the overall volume is significantly reduced compared to traditional large wind tunnels. It does not require complex infrastructure investment, significantly reducing equipment manufacturing costs and space occupation, and is suitable for deployment in small-scale scenarios such as scientific research laboratories and corporate R&D centers.

[0021] 2. The pressure holding unit first draws air into the wind tunnel unit to the set target pressure, then adjusts it to a micro-intake through the three-way valve to make the entire wind tunnel system reach the target value. Finally, the inlet and outlet valves are closed to make the wind tunnel unit in a sealed state, thus achieving stable pressure maintenance.

[0022] 3. Fully enclosed structure for long-term stable operation: The wind tunnel unit adopts a fully enclosed ring-shaped pipeline design, abandoning the traditional intake and exhaust pressure regulation mode. This fundamentally avoids the ice blockage problem and ice crystal formation caused by intake in low-temperature environments, completely solving the technical pain points of ice crystal interference testing and the inability of equipment to operate continuously for a long time, ensuring the stability and continuity of extreme environment simulation.

[0023] 4. A first rectifier is set in the power section to adjust the rotating airflow to direct current, and a second rectifier is set in the rectifier and stabilization section to reduce the turbulence of the airflow, thereby ensuring a stable stratospheric wind speed environment in the test section. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1This is a schematic diagram of a sealed low-temperature and low-pressure wind tunnel embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the structure of the first rectifier mechanism in an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of the structure of the second rectifier mechanism in an embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram of the installation structure of the transparent observation window in an embodiment of the present invention;

[0029] Figure 5 This is a curve showing the temperature change over time within the wind tunnel in an embodiment of the present invention.

[0030] Figure 6 This refers to the wind speed range provided by the drive component rotation speed under different operating conditions in the embodiments of the present invention;

[0031] in:

[0032] 1. Wind tunnel body; 1-1. Fixed flange; 2. Return pipe; 3. Drive component; 4. First rectification mechanism; 4-1. Support frame; 4-2. First rectification sleeve; 4-2a. Mounting part; 4-2b. Rectification part; 5. Second rectification mechanism; 5-1. First rectification part; 5-1a. Connection part; 5-1b. Diverging part; 5-1c. Flow stabilizing part; 5-2. Second rectification part; 5-2a. Diverging part; 5-2b. Output part; 5-3. Flow stabilizing component; 6. Transparent observation window; 7. Heat exchange mechanism; 8. Refrigerator; 9. Heat exchange fan; 10. Vent pipe; 11. Vacuum pump; 12. Inlet and outlet valves; 13. Inlet pipe; 14. Three-way valve; 15. Bracket; 16. Sealing ring; 17. Screw. Detailed Implementation

[0033] The above-described solution will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. The implementation conditions used in the embodiments may be further adjusted according to the conditions of specific manufacturers, and the implementation conditions not specified are generally those in routine experiments.

[0034] like Figure 1 The diagram shown is a structural schematic of an embodiment of the present invention, which provides a sealed low-temperature and low-pressure wind tunnel, including a wind tunnel unit, a refrigeration unit, a pressure holding unit, and a control unit.

[0035] The wind tunnel unit is a closed-loop recirculation structure, comprising a power section, a rectification and stabilization section, a contraction section, a test section, a diffusion section, and a recirculation guide section connected in sequence. Specifically, it includes a cylindrical wind tunnel body 1 and recirculation pipes 2 connected to the wind tunnel body 1 at both ends. Both the wind tunnel body 1 and the recirculation pipes 2 are made of 304 stainless steel. The wind tunnel body 1 includes a cylindrical body and detachable end caps at both axial ends of the cylindrical body. The end caps are connected to the cylindrical body with screws and sealed with sealing rings. An air inlet is provided on one of the end caps, and an air outlet is provided at the end of the outer wall of the cylindrical body 1 away from the air inlet. First connecting flanges are provided at the air inlet and the air outlet, respectively. The two ends of the recirculation pipes 2 are fixedly connected to the first connecting flanges via second connecting flanges and sealed with sealing rings.

[0036] The loop pipe 2 is arranged in a ring shape from the outlet to the inlet. The part of the loop pipe 2 near the inlet of the wind tunnel body 1 forms the power section. The rectification and stabilization section is located inside the wind tunnel body 1 and forms a contraction section at the outlet. The test section is located downstream of the contraction section inside the wind tunnel body 1. The diffusion section is located downstream of the test section inside the wind tunnel body 1. The part of the return pipe 2 near the outlet of the wind tunnel body 1 is the return flow guiding section.

[0037] The power section is equipped with a drive component 3 that drives the gas flow and a first rectifier mechanism 4 that adjusts the rotating airflow generated by the drive component 3 into a direct current airflow. The drive component 3 uses a brushless DC fan, whose motor and bearings undergo special lubrication and sealing treatment, allowing it to operate continuously in extreme environments with air pressures as low as 1000 Pa and temperatures as low as -65℃. The fan has a maximum airflow of 54 CFM and achieves stepless speed regulation via a 0-5V PWM signal, corresponding to a simulated wind speed range of 0 to 20 m / s within the test section. Figure 6 The figure shows the wind speed range provided by the drive component 3 under different operating conditions. A wind speed detection component is also installed in the test section. Preferably, the wind speed detection component is a miniature hot-wire anemometer with a range of 0-25 m / s and an accuracy of <3%, to detect the wind speed and transmit the signal to the control unit. The control unit then adjusts the motor frequency of the brushless DC fan to regulate the wind speed.

[0038] like Figure 2As shown, the first rectifying mechanism 4 includes a support frame 4-1 installed on the inner wall of the return pipe 2 and located downstream of the drive component 3, and a first rectifying sleeve 4-2 fixed on the support frame 4-1. The first rectifying sleeve 4-2 extends axially along the return pipe 2 of the power section. Specifically, the first rectifying sleeve 4-2 includes a mounting portion 4-2a arranged coaxially with the return pipe 2 of the power section and a rectifying portion 4-2b connected to the mounting portion 4-2a. The rectifying portion 4-2b is conical and tapers along the airflow direction, thereby adjusting the rotating airflow into a direct current airflow. The support frame 4-1 includes multiple connecting plates connecting the mounting portion 4-2a and the inner wall of the return pipe 2. Preferably, the multiple connecting plates are evenly spaced circumferentially along the mounting portion 4-2a.

[0039] To facilitate the installation of the drive component 3 and the first rectifier mechanism 4, the return pipe 2 at the power section can be disconnected and connected via a flange. The drive component 3 is installed at the end of one section of the return pipe 2, while the first rectifier mechanism 4 is installed at the end of the other section of the return pipe 2. The first rectifier sleeve 4-2 and the support frame 4-1 are both made of 304 stainless steel. The support frame 4-1 is welded and fixed to the first rectifier sleeve 4-2 and the return pipe 3 respectively.

[0040] A second rectification mechanism 5 is provided in the rectification and stabilization section to reduce airflow turbulence, specifically, as follows: Figure 3 As shown, the second rectification mechanism 5 includes a second rectification sleeve installed inside the wind tunnel body 1 and a flow stabilizing component 5-3 installed inside the second rectification sleeve. The flow stabilizing component 5-3 includes a honeycomb rectifier installed on the inner wall of the second rectification sleeve and at least one layer of damping mesh arranged on the honeycomb rectifier. The wind speed can be reduced by the honeycomb rectifier and the damping mesh to achieve flow stabilization.

[0041] In this example, the second rectifying sleeve includes a detachably connected first rectifying section 5-1 and a second rectifying section 5-2. The first rectifying section 5-1 includes a connecting section 5-1a sealed to the return pipe 2, a flow stabilizing section 5-1c, and a gradually expanding section connecting the flow stabilizing section 5-1c and the connecting section 5-1a. The second rectifying section 5-2 includes a gradually contracting section 5-2a extending along the airflow direction and an output section 5-2b connected to the gradually contracting section 5-2a. A support platform is provided at one end of the first rectifying section 5-1 near the second rectifying section 5-2, and the flow stabilizing assembly 5-3 is mounted on the support platform by multiple screws. The airflow velocity entering the first rectifying section 5-1 from the power section is reduced and stabilized by the flow stabilizing assembly 5-3, and then accelerated and contracted by the second rectifying section 5-2 before being sent to the test section.

[0042] The test section is equipped with a support 15 for fixing the sample, such as a column fixed on the inner wall of the wind tunnel body 1 and extending radially. During the test, the sample is fixed on the column.

[0043] To facilitate the placement of test samples and the observation of the test, such as Figure 4 As shown, a transparent observation window 6 is detachably provided on the outer wall of the wind tunnel body 1 at a position corresponding to the support 15. Specifically, a fixing flange 1-1 is provided on the outer wall of the wind tunnel body 1, and the transparent observation window 6 is fixedly connected to the fixing flange 1-1. At the same time, a sealing ring 16 is provided between the transparent observation window 6 and the fixing flange 1-1 for sealing. When it is necessary to change the sample, the transparent observation window 6 is removed. After the sample is placed, the transparent observation window 6 is reinstalled to maintain the system's airtightness.

[0044] The cooling unit, used to cool the gas inside the wind tunnel body 1, includes a heat exchange mechanism 7 and a cooler 8 connected to the heat exchange mechanism 7. In this example, the heat exchange mechanism 7 includes heat exchange coils installed inside the wind tunnel body 1, the heat exchange coils being arranged in a spiral shape and connected to the cooler 8 at both ends. It should be understood that in other embodiments, heat exchange coils can also be installed on the outer wall of the wind tunnel body 7, or on the outer wall of the return pipe 2, both of which can achieve gas cooling.

[0045] The heat exchange coil is made of copper, with a total length of 50m and an inner diameter of 10mm, increasing the heat exchange area to improve cooling efficiency. Refrigerator 8 uses an external cascaded compressor refrigeration cycler with a cooling power of 4400 W and a minimum cooling temperature of -110℃ (no load), suitable for low-temperature environments at altitudes of 0-25 km. Anhydrous ethanol is selected as the low-temperature circulating medium; its freezing point is lower than the target minimum cooling temperature, and its boiling point makes it less prone to vaporization under the target low-pressure environment, ensuring stable operation of the refrigeration cycle.

[0046] To improve the uniformity of heat exchange, a heat exchange fan 9 is installed inside the wind tunnel body 1. The heat exchange fan 9 enhances gas circulation, making the temperature of the return gas more uniform.

[0047] Simultaneously, at least one temperature sensor is installed within the wind tunnel unit. The temperature sensor and the cooler 8 are connected to the control unit via signal connections. The temperature sensor provides feedback on the temperature within the wind tunnel unit, which in turn allows the control unit to adjust the medium flow rate and compressor power of the cooler 8, forming a closed-loop PID control system to achieve precise temperature regulation. The temperature control accuracy can reach ±2℃. In this example, one temperature sensor can be installed in the test section, and one each in the power section and the return flow guide section to achieve precise temperature regulation. Figure 5 As shown, this is a curve showing the temperature change over time inside the wind tunnel body 1.

[0048] It should be understood that in other implementations, the cooler 8 can also be -40°C; the TEC array achieves heat transfer by attaching thermally conductive silicone grease to the end of the copper coil.

[0049] To keep the entire system warm, an insulation layer is installed on the outer wall of the wind tunnel unit. The insulation layer is made of foam and is fixed to the outer wall of the wind tunnel unit with adhesive.

[0050] The pressure-maintaining unit, used to maintain the pressure of the gas within the wind tunnel unit, includes a ventilation pipe 10 connected to the wind tunnel unit at one end, inlet and outlet valves 12 installed on the ventilation pipe 10, a vacuum pump 11 connected to the other end of the ventilation pipe 10, an inlet pipe 13 connecting the ventilation pipe 10 to the section between the inlet and outlet valves 12 and the vacuum pump 11, and a three-way valve 14 installed between the inlet pipe 13 and the ventilation pipe 10. A pressure sensor is installed on the inner wall of the wind tunnel body 1. The pressure sensor, vacuum pump 11, and three-way valve 14 are all connected to the control unit. The vacuum pump 11 is a rotary vane pump with a pumping speed of 240 L / min and an ultimate vacuum of 0.06 Pa, which can meet the simulation requirements of low-pressure environments at altitudes of 0-25 km. It is equipped with a pressure sensor with a range of 0 Pa to atmospheric pressure and an accuracy of 0.1% FS.

[0051] The adjustment process is as follows: After setting the target pressure, open the main inlet and outlet valve 12, start the vacuum pump 11 to pump air, and after reaching the required vacuum level, turn off the vacuum pump 11. Switch to micro airflow intake through the three-way valve 14. After the pressure reaches the target value, close the inlet and outlet valves. Relying on the closed structure characteristics and excellent airtightness of the closed-loop wind tunnel, the pressure can be stably maintained, and the system pressure control accuracy can reach ±0.1 kPa.

[0052] The control unit uses a PLC controller and is equipped with a touch screen connected to the PLC controller to realize human-machine interaction, complete parameter setting and display, and can also be equipped with an alarm connected to the PLC controller to trigger an alarm when the parameters exceed the set range. These are existing technologies and will not be described in detail in this invention.

[0053] In summary, this wind tunnel system successfully simulated the 0-25km high-altitude environment with a wind speed simulation range of 0-20m / s within the test section. Relying on a fully enclosed sealed design and closed-loop precision control technology, it effectively avoided ice blockage and ice crystal interference problems in low-temperature environments, achieving stable long-term operation for more than 24 hours. It can provide a real and reliable test environment for the ground calibration and performance verification of stratospheric wind speed sensors, verifying the feasibility and superiority of the technical solution of this invention.

[0054] The above examples are merely illustrative of the technical concept and features of the present invention, intended to enable those skilled in the art to understand the content of the invention and implement it accordingly, and should not be construed as limiting the scope of protection of the present invention. All equivalent transformations or modifications made according to the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A sealed low-temperature, low-pressure wind tunnel, characterized in that, include: The wind tunnel unit is a closed-loop recirculation structure, comprising a power section, a rectification and stabilization section, a contraction section, a test section, a diffusion section, and a recirculation guide section connected in sequence. The power section is equipped with a driving component that drives the gas flow and a first rectification mechanism that adjusts the rotating airflow generated by the driving component into a direct current airflow. The rectification and stabilization section is equipped with a second rectification mechanism that reduces the turbulence of the airflow. The wind tunnel unit is equipped with at least one temperature measuring component, at least one pressure measuring component, and at least one wind speed measuring component. A refrigeration unit, used to cool the gas inside the wind tunnel unit, includes a heat exchange mechanism and a refrigerator connected to the heat exchange mechanism; The pressure holding unit is used to maintain the pressure of the gas in the wind tunnel unit. It includes a ventilation pipe connected to the wind tunnel unit at one end, an inlet and outlet valves provided on the ventilation pipe, a vacuum pump connected to the other end of the ventilation pipe, an inlet pipe connected to the section of the ventilation pipe located between the inlet and outlet valves and the vacuum pump, and a three-way valve provided between the inlet pipe and the ventilation pipe. The control unit, including the temperature measuring component, pressure measuring component, wind speed measuring component, drive component, refrigerator, vacuum pump, and three-way valve, is connected to the control unit via signals.

2. The sealed low-temperature and low-pressure wind tunnel according to claim 1, characterized in that: The wind tunnel unit includes a wind tunnel body and return pipes connected to the wind tunnel body at both ends. The portion of the return pipe near the air inlet of the wind tunnel body forms the power section. The rectification and stabilization section is located inside the wind tunnel body, and the contraction section is formed at the air outlet. The test section is located downstream of the contraction section inside the wind tunnel body. The diffusion section is located downstream of the test section inside the wind tunnel body. The portion of the return pipe near the air outlet of the wind tunnel body forms the return flow guiding section.

3. The sealed low-temperature and low-pressure wind tunnel according to claim 2, characterized in that: The first rectification mechanism includes a support frame installed on the inner wall of the return pipe and located downstream of the drive component, and a first rectification sleeve fixed to the support frame, the first rectification sleeve extending axially along the return pipe of the power section.

4. The sealed low-temperature and low-pressure wind tunnel according to claim 3, characterized in that: The first rectifying sleeve includes a mounting part coaxially arranged with the return pipe of the power section and a rectifying part connected to the mounting part. The rectifying part is conical and gradually narrows along the airflow direction. The support frame includes a plurality of connecting plates connecting the mounting part and the inner wall of the return pipe.

5. The sealed low-temperature and low-pressure wind tunnel according to claim 2, characterized in that: The second rectification mechanism includes a second rectification sleeve installed in the wind tunnel body and a flow stabilizing component installed in the second rectification sleeve. The flow stabilizing component includes a honeycomb rectifier installed on the inner wall of the second rectification sleeve and at least one layer of damping mesh arranged on the honeycomb rectifier.

6. The sealed low-temperature and low-pressure wind tunnel according to claim 5, characterized in that: The second rectifier sleeve includes a first rectifier section and a second rectifier section that are detachably connected. The first rectifier section includes a connecting section connected to the return pipe, a flow stabilizing section, and a gradually expanding section connecting the connecting section and the flow stabilizing section. The second rectifier section includes a gradually contracting section extending along the airflow direction and an output section connected to the gradually contracting section. The rectifier assembly is installed at one end of the first rectifier section near the second rectifier section.

7. The sealed low-temperature and low-pressure wind tunnel according to claim 2, characterized in that: The test section is equipped with a support for fixing the sample, and a transparent observation window is detachably provided on the outer wall of the wind tunnel body at a position corresponding to the support.

8. The sealed low-temperature and low-pressure wind tunnel according to claim 7, characterized in that: The wind tunnel body is provided with a fixed flange on its outer wall, and the transparent observation window is detachably connected to the fixed flange.

9. The sealed low-temperature and low-pressure wind tunnel according to claim 2, characterized in that: The heat exchange mechanism includes a heat exchange coil installed inside the wind tunnel body, and a heat exchange fan is installed inside the wind tunnel body.

10. The sealed low-temperature and low-pressure wind tunnel according to claim 1, characterized in that: An insulation layer is fixed to the outer wall of the wind tunnel unit.

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