A temperature-controllable open low-Reynolds number intelligent wind tunnel

Abstract

A temperature-controllable open low-Reynolds number intelligent wind tunnel, which relates to the field of blade wind tunnel tests in the field of turbomachinery. The present invention solves the problem that the existing low-Reynolds number wind tunnel test bench can only perform simulations at room temperature and there is a problem that low-Reynolds number tests cannot be performed with heating. The air intake device (A-11) of the present invention is connected to the air intake heater (A-14) through a main air intake regulating valve (A-12) and an auxiliary air intake regulating valve (A-13) arranged in parallel, and the air flow sucked from the atmosphere by the air intake device (A-11) enters the first expansion joint (A-15) after being heated by the air intake heater (A-14) and is connected to the wind tunnel body (B), the secondary flow system (C) is connected to the experimental cabin (B-23) in the wind tunnel body (B), and the exhaust system (D) is connected to the exhaust side of the experimental cabin (B-23). ​​The present invention is used for gas-thermal performance experiments of key components of turbomachinery and high-altitude aircraft simulation tests in low-Reynolds number environments.

Description

Technical Field

[0001] The present invention relates to an aerodynamic performance test technology for key components of turbine machinery of high-altitude aircraft, aero-engines and gas turbines, and in particular to a temperature-controllable open low-Reynolds number intelligent wind tunnel. Background Art

[0002] When an aircraft operates at high altitudes (above 10,000 meters), the density of the atmosphere is significantly reduced compared to that on the ground, and the Reynolds number, a key aerodynamic parameter affecting flow, becomes very low, which leads to low-Reynolds-number flow problems. This is a problem that must be solved in the design of high-altitude aircraft and aircraft engines. At the same time, the demand for high-altitude aircraft and aircraft engines at home and abroad is on the rise. The lack of a low-Reynolds-number database for engines restricts engine development. The number of test benches in China with low-Reynolds-number wind tunnels that can simulate high altitudes is limited, resulting in high testing costs and an inability to meet the large demands of various research and development units. A survey of domestic low-Reynolds-number test benches found that domestic low-Reynolds-number wind tunnel test benches only perform simulations at room temperature and do not have the ability to perform heated low-Reynolds-number tests.

[0003] For example, the patent application number CN108254130B, entitled "Continuous High-Temperature Sealing Performance Testing Wind Tunnel Apparatus," includes an air compressor, a gas cylinder, a normal-temperature pressure gauge, a shutoff valve (a), a pressure reducing valve, an air flow meter (a), a ducted air heater, a shutoff valve (b), a high-temperature thermometer (a), a high-temperature pressure gauge, a test section, an air flow meter (b), and a high-temperature thermometer (b). The apparatus uses an air compressor to pressurize air and store it in a gas cylinder. The pressure is then regulated by a pressure reducing valve, followed by heating by a ducted air heater, before passing through the test section. The test piece is secured within a specific groove within the test section. Adjusting the distance between the test section's upper cover and base by replacing adjustable gaskets of varying sizes changes the compression of the test piece. High-temperature thermometers (a), high-temperature pressure gauges, air flow meter (b), and high-temperature thermometers (b) installed before and after the sealing apparatus allow the sealing and thermal insulation parameters of the test piece to be measured under varying compressions, pressure differentials, and temperatures. While wind tunnel testing is possible, it is primarily a test focused on sealing performance. It is not suitable for blade performance tests of aircraft engines under low Reynolds number conditions and at different temperatures.

[0004] Among them, when aircraft engines operate at low Reynolds numbers, the flow in the blade slots is often in a laminar or laminar-turbulent mixed flow state, which easily produces flow separation on the suction surface of the blade. In severe cases, it will cause flow blockage, which in turn affects the matching between the compressor and turbine blade rows, resulting in reduced efficiency and performance of engine components, and ultimately causing reduced engine thrust, increased fuel consumption, and poor working stability and reliability, which has a huge impact on the completion of flight missions.

[0005] In summary, the existing low Reynolds number wind tunnel test bench can only perform simulations at room temperature, and there is a problem that low Reynolds number tests with heating cannot be performed. Summary of the Invention

[0006] The present invention aims to address the problem that existing low-Reynolds number wind tunnel test rigs can only perform simulations at room temperature and are unable to perform heated low-Reynolds number tests. Furthermore, it provides a temperature-controllable open low-Reynolds number intelligent wind tunnel.

[0007] The technical solution of the present invention is:

[0008] A temperature-controllable open low-Reynolds number intelligent wind tunnel includes an air intake system, a wind tunnel body, a secondary flow system and an exhaust system. The air intake system includes an air intake device, a main air intake regulating valve, an auxiliary air intake regulating valve, an air intake heater and a first expansion joint. The air intake device is connected to the air intake heater through the main air intake regulating valve and the auxiliary air intake regulating valve arranged in parallel, and the air flow drawn from the atmosphere by the air intake device enters the first expansion joint after being heated by the air intake heater; the first expansion joint is connected to the wind tunnel body, the secondary flow system is connected to the experimental cabin in the wind tunnel body, and the exhaust system is connected to the exhaust side of the experimental cabin.

[0009] Furthermore, the air intake system also includes a flow guide device and an air intake pipe, which are installed between the air intake device and the main air intake regulating valve; the flow guide device includes a conical shell and a metal mesh, the conical shell is connected to the air intake pipe in sequence, and the metal mesh is installed at the large end of the conical shell, wherein the metal mesh includes an outer metal mesh and an inner metal mesh, and the outer metal mesh and the inner metal mesh are installed in sequence at the large end of the conical shell.

[0010] Furthermore, the wind tunnel body includes a diffuser section, a stabilizer section and a test chamber, which are connected sequentially from left to right, wherein the test chamber includes a convergence section, a nozzle section and a test section, which are connected sequentially from left to right.

[0011] Furthermore, the test section includes an inner shell, an outer shell, a positioning block assembly, a plurality of connecting limit members, an inner disc, an outer disc, an angle of attack adjustment drive member, an upper baffle assembly and a lower baffle assembly; the inner shell and the outer shell are connected by a plurality of connecting limit members, the positioning block assembly is installed on the air inlet side of the inner shell and the outer shell, one end of the upper baffle assembly is rotatably connected to the positioning block assembly, and is used to clamp on the blade of the upper part of the blade to be tested, and the lower baffle assembly slides with the side of the positioning block assembly and moves up and down to support the lower part of the blade to be tested; the inner disc and the outer disc are rotatably installed on the inner shell and the outer shell respectively, and rectangular holes are respectively opened on the inner disc and the outer disc, wherein the blade to be tested is installed in the rectangular hole, and scales are engraved on the outer side of the inner shell to measure the rotation angle of the inner disc and the outer disc, and the angle of attack adjustment drive member is installed on the outer side of the inner disc, and the angle of attack adjustment drive member drives the inner disc and the outer disc to rotate simultaneously to achieve a change in the angle of attack of the blade to be tested.

[0012] Preferably, the positioning block assembly includes an upper positioning block and a lower positioning block, which are fixedly mounted on the air inlet side of the inner shell and the outer shell, and are arranged in parallel.

[0013] Preferably, the end of the lower positioning block is provided with a 45° bevel.

[0014] Preferably, the connection limiter includes a distance sleeve and a bolt. The bolt passes through the outer shell and is inserted into the distance sleeve between the inner shell and the outer shell, extends out of the inner shell, and is then installed on the inner shell through a nut.

[0015] Furthermore, the secondary flow system includes an air compressor, a dryer, a gas tank, a first switch valve, a first regulating valve and a flow meter, and the air compressor, the dryer, the gas tank, the first switch valve, the first regulating valve and the flow meter are connected in sequence.

[0016] Furthermore, it also includes an electrical system, a test system, a video surveillance system, auxiliary process equipment and a cooling water system. The electrical system, the test system, the video surveillance system and the auxiliary process equipment are electrically connected to the air intake system, the wind tunnel body and the secondary flow system respectively, and the cooling water system is connected to the exhaust system.

[0017] Furthermore, the exhaust system includes a second expansion joint, a heat exchanger, multiple second switch valves and multiple vacuum pumps. The multiple second switch valves are connected in parallel, and each second switch valve is connected to a vacuum pump. After the second expansion joint and the heat exchanger are connected, they are connected to the multiple second switch valves arranged in parallel.

[0018] Compared with the prior art, the present invention has the following effects:

[0019] 1. Compared to existing low-Reynolds number wind tunnels, the present invention utilizes variable frequency control for the suction unit (referring to vacuum pump D-44), and the main and auxiliary regulating valves at the inlet of intake system A effectively adjust the low Reynolds number range. The intake heater A-14 in intake system A controls the inlet airflow temperature to meet test requirements. Furthermore, the nozzle section and test section in the test chamber can be installed or removed according to test requirements, allowing for performance testing of fan, compressor, and turbine blades or model testing of three-dimensional high-altitude aircraft. In summary, a temperature-controlled, open-type, low-Reynolds number intelligent wind tunnel is capable of testing high-altitude aircraft, aircraft engine fans, compressors, and turbine blades, respectively, meeting the requirements for temperature control and measurement within a relatively low Reynolds number range.

[0020] 2. The wind tunnel of the present invention can provide a test environment for high-altitude aircraft and aircraft engines under low Reynolds number conditions, and the inlet temperature of the wind tunnel is controllable. Blade profile research is a fundamental and key task in the development of aircraft engines. To improve the overall performance of the engine, the blade profile optimization and improvement of components such as fans, compressors, and turbines is a long-term, iterative process. Plane cascade tests are relatively routine and are conducted more frequently. This test bench can meet the test and testing needs of high-altitude aircraft and aircraft engines under low Reynolds number conditions. Specific tests that can be carried out include: low-Reynolds number cascade performance tests, low-Reynolds number cascade cooling effect tests, low-Reynolds number flow display tests, digital twin technology for cascade tests, and modeling tests of high-altitude aircraft.

[0021] 3. Test section B-26 of the present invention is constructed by mounting the cascade test piece on the rectangular holes of the inner and outer discs and securing them thereto with a plurality of bolts. When the cascade test piece is mounted on the cascade test piece, the upper nut-screw pair first drives the upper retractable wall plate to lift via the upper lifting connector. After the cascade test piece is secured, the distal end of the upper retractable wall plate rests against the uppermost cascade. The lower nut-screw pair then pushes the lower retractable wall plate upward along the inclined surface of the lower positioning block, thereby dragging the lower end of the cascade test piece. When the angle of attack needs to be adjusted for cascade testing, the handle is rotated. After the steering assembly turns, the handle drives the worm, which in turn drives the worm gear, which in turn drives the inner and outer discs to rotate simultaneously. Since the cascade test piece is mounted on the inner and outer discs, the angle of attack of the cascade test piece can be changed by rotating the worm gear while maintaining the direction of the inlet airflow. This allows for cascade wind tunnel testing at various angles of attack.

[0022] 4. The upper and lower retractable panels of the present invention are capable of rotation and movement, making them suitable for wind tunnel testing of various cascade blade types. Furthermore, wind tunnel testing of turbine and compressor cascades of varying designs requires only replacing the test blades themselves, while other components remain installed and usable, minimizing testing costs.

[0023] 5. The present invention adopts manual control of the worm gear to achieve effective and high-precision adjustment of the test blade angle, avoiding the failure and adverse problems caused by the use of an electronic control structure in a high temperature environment.

[0024] 6. The test section disc structure of the present invention can change the rotation angle of the adjustable blade cascade. During the blade cascade test, the blade attack angle value of the test blade cascade can be monitored and adjusted, thereby optimizing the adjustable angle blade cascade test process. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0026] Figure 2 It is a schematic diagram of the structure of the guide device A-16 and the air intake duct A-17.

[0027] Figure 3 It is a schematic diagram of the structure of the stable segment B-22.

[0028] Figure 4 This is an axonometric view of test section B-26.

[0029] Figure 5 yes Figure 4 Schematic diagram of the structure after removing the four-degree-of-freedom displacement mechanism 23.

[0030] Figure 6 yes Figure 5 Exploded diagram.

[0031] Figure 7 yes Figure 4 Bottom view of .

[0032] Figure 8 It is a structural diagram of the air flow channel.

[0033] Figure 9 It is a schematic diagram of the overall framework of the video surveillance system G.

[0034] Figure 10 This is a graph showing the relationship between the Mach number and mass flow rate at the inlet of the test piece under the throttling and heating conditions at the blade inlet (pressure 10000Pa, temperature 800K).

[0035] Figure 11This is a graph showing the relationship between the Mach number and mass flow rate at the inlet of the test piece under the throttling and heating conditions at the blade inlet (pressure 10000Pa, temperature 800K).

[0036] in:

[0037] A. Air intake system, A-11. Air intake device, A-12. Main air intake regulating valve, A-13. Auxiliary air intake regulating valve, A-14. Air intake heater, A-15. First expansion joint, A-16. Flow guide device, A-17. Air intake duct;

[0038] B, wind tunnel main body, B-21, diffuser section, B-22, stabilization section, B-23, test chamber, B-24, convergence section, B-25, nozzle section, B-26, test section;

[0039] C, secondary flow system, C-31, air compressor, C-32, dryer, C-33, gas tank, C-34, first switch valve, C-35, first regulating valve, C-36, flow meter,

[0040] D, exhaust system, D-41, second expansion joint, D-42, heat exchanger, D-43, second on-off valve, D-44, vacuum pump,

[0041] 1. Inner housing, 2. Outer housing, 3. Inner disc, 4. Outer disc, 5. Rectangular hole, 6. Upper positioning block, 7. Lower positioning block, 8. Distance sleeve, 9. Bolt, 10. Worm gear, 11. Worm, 12. Handle, 13. Steering assembly, 14. Worm mounting seat, 15. Upper retractable wall plate, 16. Rotating connector, 17. Upper lifting connector, 18. Upper nut and screw pair, 19. Lower retractable wall plate, 20. Lifting support, 21. Lower lifting connector, 22. Lower nut and screw pair, 23. Four-degree-of-freedom displacement mechanism, 20-1. Bracket, 20-2. Slide rail, 20-3. Slider;

[0042] E. Electrical system, F. Testing system, G. Video surveillance system, H. Auxiliary process equipment, I. Cooling water system. DETAILED DESCRIPTION

[0043] Specific implementation method 1: Combination Figures 1 to 11To illustrate this embodiment, this embodiment includes an air intake system A, a wind tunnel body B, a secondary flow system C and an exhaust system D. The air intake system A includes an air intake device A-11, a main air intake regulating valve A-12, an auxiliary air intake regulating valve A-13, an air intake heater A-14 and a first expansion joint A-15. The air intake device A-11 is connected to the air intake heater A-14 through the main air intake regulating valve A-12 and the auxiliary air intake regulating valve A-13 arranged in parallel, and the air flow drawn from the atmosphere by the air intake device A-11 is heated by the air intake heater A-14 and then enters the first expansion joint A-15; the first expansion joint A-15 is connected to the wind tunnel body B, the secondary flow system C is connected to the experimental cabin B-23 in the wind tunnel body B, and the exhaust system D is connected to the exhaust side of the experimental cabin B-23.

[0044] This embodiment adopts an open wind tunnel system, which works in a suction mode under the suction action of the exhaust unit (referring to the vacuum pump D-44) (the exhaust unit adopts variable frequency control, which can reduce the energy consumption in the test project and improve the efficiency of test parameter adjustment); its inlet condition is the atmospheric environment, and the air flow at the outlet of the test section passes through the heat exchanger and is connected to the exhaust unit (referring to the vacuum pump D-44), and finally discharged into the atmosphere; after the test is started, the exhaust unit (referring to the vacuum pump D-44) forms a low back pressure at the outlet of the test section to meet the low Reynolds number requirement, and the air passes through the intake pipe and is heated by the heater (which can be Oil, electric heating, maximum temperature heated to 800K), the main and auxiliary pressure regulating valves are adjusted, the diffuser section enters the pressure regulating box for rectification, and then enters the two-dimensional nozzle through the convergent section (when simulating high-altitude aircraft, the nozzle section and test section in the test chamber can be removed, and then the high-altitude aircraft can be tested under the low-altitude Reynolds number state in three-dimensional space), forming an airflow of a certain speed into the test section to carry out a blowing test on the model test piece; according to needs, the cooling effect test research of related secondary flows can be carried out to simulate the blade cooling; among them, under the heating and throttling state, when the Mach number is 0.7, the maximum Reynolds number is 1.6953×10 4 .

[0045] like Figure 1 As shown, by jointly controlling the vacuum pump in the exhaust system and using variable frequency control to vary the vacuum pump's speed to adjust the unit's power, the main and auxiliary intake control valves are simultaneously adjusted to control the Mach and Reynolds numbers at the cascade inlet. When the vacuum exhaust unit achieves the Mach number at the cascade inlet at a specific speed, the test piece inlet valve is controlled to regulate the pressure and, in turn, the Reynolds number. Because the unit utilizes combined extraction, the fan outlet pressure must be above atmospheric pressure to ensure proper exhaust.

[0046] Specific implementation method 2: Combination Figure 1To illustrate this embodiment, the air intake system A of this embodiment further includes a flow guide device A-16 and an air intake duct A-17. The flow guide device A-16 and the air intake duct A-17 are installed between the air intake device A-11 and the main air intake regulating valve A-12.

[0047] The guide device A-6 includes a conical shell and a metal mesh. The conical shell is connected in sequence with the air intake pipe A-17. The metal mesh is installed at the large end of the conical shell. The metal mesh includes an outer metal mesh and an inner metal mesh. The outer metal mesh and the inner metal mesh are installed in sequence at the large end of the conical shell.

[0048] The present invention adopts an open cycle, that is, the air flow of the intake system comes from the atmospheric environment, flows into the guide device and the intake pipe (such as Figure 2 As shown in the figure, the flow guide device is conical in shape, with two layers of metal mesh added at its entrance: one coarse mesh and one fine mesh. Airflow passes through the fine mesh first, then the coarse mesh, following the direction of airflow. The coarse mesh provides support and prevents larger objects such as birds from entering. The fine mesh filters out dust and impurities, protecting the heater, test piece, heat exchanger, and vacuum pump unit. After adjustment by the main and auxiliary control valves, the airflow enters the heater for heating. The heater can use oil or electricity to heat the airflow to the required temperature under test conditions (taking aviation kerosene heating as an example, its calorific value is 43.5×106 J / kg. Assuming a maximum intake system flow of 5.5 kg / s, an atmospheric air temperature of 288.15 K, a combustion efficiency of 0.9, and an isentropic index of 1.33 for the fuel gas, heating the airflow to 800 K requires a maximum fuel system supply of 323 kg / h). The heated fluid passes through expansion joint 15 and enters the wind tunnel body 2.

[0049] Specific implementation method three: Combination Figure 1 To describe this embodiment, the wind tunnel body B of this embodiment includes a diffuser section B-21, a stabilizer section B-22, and a test chamber B-23, which are connected sequentially from left to right. The test chamber B-23 includes a convergent section B-24, a nozzle section B-25, and a test section B-26, which are connected sequentially from left to right.

[0050] The airflow entering the wind tunnel body of the present invention first enters the diffusion section, and the outlet of the diffusion section is the stable section. The structure of the stable section is as follows: Figure 3 As shown, the stabilization section is typically 2 to 3 times the length of the nozzle and consists of a shell, perforated plate, damping mesh, and honeycomb. The purpose of the stabilization section is to uniformize the airflow entering the nozzle and reduce turbulence, thereby ensuring the quality of the airflow at the inlet of the convergent section and the nozzle section, and thus ensuring the quality of the airflow field at the nozzle outlet entering the test section.

[0051] The airflow out of the stable section enters the experimental cabin, which includes a convergence section, a nozzle section and a test section. The test cabin provides stable low pressure and sealing conditions for its test section. The airflow entering the experimental cabin first reaches the convergence section, where the function of the convergence section is to accelerate the airflow and at the same time make it reach the speed required for the test, and should meet the following requirements: when the airflow flows along the convergence section, there is no separation on the cave wall; the airflow at the outlet of the convergence section is required to be uniform, straight and stable; the airflow out of the convergence section enters the nozzle section, and the function of the nozzle is to ensure that the test section entrance obtains a uniform airflow of the designed Mach number to ensure the quality of the test flow field; finally, the airflow enters the test section.

[0052] Specific implementation method four: Combination Figures 4 to 8 Explain this embodiment, this embodiment comprises inner shell 1, outer shell 2, positioning block assembly, multiple connection limiters, inner disc 3, outer disc 4, angle measuring ruler, attack angle adjustment drive member, upper baffle assembly and lower baffle assembly; inner shell 1 and outer shell 2 are connected by multiple connection limiters, positioning block assembly is installed on the air inlet side of inner shell 1 and outer shell 2, one end of upper baffle assembly is rotatably connected with positioning block assembly, used for being clamped on the cascade of the upper part of cascade to be tested piece, lower baffle assembly and side sliding engagement of positioning block assembly The combined lifting motion is used to support the lower part of the blade to be tested; the inner disk 3 and the outer disk 4 are rotatably mounted on the inner shell 1 and the outer shell 2 respectively, and rectangular holes 5 are respectively opened on the inner disk 3 and the outer disk 4, wherein the blade to be tested is installed in the rectangular hole 5, the angle measuring ruler is installed on the outside of the inner shell 1 to measure the rotation angle of the inner disk 3 and the outer disk 4, and the angle of attack adjustment drive is installed on the outside of the inner disk 3, and the angle of attack adjustment drive drives the inner disk 3 and the outer disk 4 to rotate simultaneously to realize the change of the angle of attack of the blade to be tested.

[0053] The test section of this embodiment is the core part of the wind tunnel, and its function is to install and fix the test piece. The cascade test section also has the function of adjusting the angle of attack of the cascade inlet. The adjustment range of the angle between the test piece's frontal line and the incoming airflow is -20° to 70° (the angle between the cascade's frontal line and the vertical line), and the adjustment accuracy is not less than 0.10°. The main test parameters are also measured in the test section; Figure 4 The disc mechanism of the test section is shown, which has the function of adjusting the inlet angle of attack of the cascade, adjusting the height of the upper and lower plates, and performing manual adjustment.

[0054] In this embodiment, the rectangular holes 5 formed on the inner and outer disks 3 and 4 are of different sizes, forming stepped rectangular holes. Multiple threaded holes are also formed around the inner and outer disks 3 and 4. Since the distance between the inner and outer disks 3 and 4 is relatively limited in actual use, there are two ways to install the cascade test piece: one is to form the cascade test piece as a single unit and fit it into the stepped rectangular hole; the other is to first attach an upper mounting plate to the inner disk 3 using multiple bolts, then attach multiple cascades to the upper mounting plate, and finally attach the lower mounting plate to the multiple cascades while simultaneously attaching it to the outer disk 4. The entire installation process takes into account that different cascade test pieces are suitable for different installation methods, making testing more flexible.

[0055] In actual use, the inner disc 3 and the outer disc 4 are positioned and connected by multiple latches, ensuring the reliability of the connection between the inner disc 3 and the outer disc 4 and the consistency of the angle during rotation. In addition, the latches between the inner disc 3 and the outer disc 4 are easy and quick to install.

[0056] Specific implementation method five: Combination Figure 6 and Figure 8 This embodiment describes a positioning block assembly comprising an upper positioning block 6 and a lower positioning block 7. The upper positioning block 6 and the lower positioning block 7 are fixedly mounted on the air inlet side of the inner housing 1 and the outer housing 2, and are arranged parallel to each other. Other components and connections are the same as those in the first embodiment.

[0057] The upper and lower positioning blocks 6 and 7 of this embodiment connect the inner and outer shells 1 and 2, and also serve as air inlets, providing the largest opening in the air intake passage. During installation, bolts connect the upper and lower positioning blocks 6 and 7, as well as the inner and outer shells 1 and 2. The lower positioning block 7 also secures the lower retractable panel, preventing it from shifting during movement.

[0058] Specific implementation method six: combination Figure 6 and Figure 8 To describe this embodiment, the end of the lower positioning block 7 of this embodiment is provided with a 45° bevel.

[0059] This arrangement ensures that the lower shrinkage wall panel moves along its oblique edge during movement, with smooth transition and high movement precision of the lower shrinkage wall panel. Other components and connection relationships are the same as those in the first or second embodiment.

[0060] Specific implementation method seven: combination Figure 6To illustrate this embodiment, the connection limiter of this embodiment includes a distance sleeve 8 and a bolt 9. The bolt 9 passes through the outer shell 2 and is inserted into the distance sleeve 8 located between the inner shell 1 and the outer shell 2, and extends out of the inner shell 1, and is then installed on the inner shell 1 through a nut.

[0061] With this arrangement, this embodiment does not directly connect the inner shell 1 and the outer shell 2 with bolts. Instead, a distance sleeve 8 is mounted on the bolts, which not only achieves positioning but also serves as a connection. The other components and connection relationships are the same as any of the specific embodiments 1 to 3.

[0062] This embodiment is also convenient for assembly and disassembly, which is mainly reflected in that when testing different blade cascade test pieces, different lengths of distance sleeves 8 can be selected, which has a wide range of applications and is more flexible. One testing machine can be used to test blade cascades of various models.

[0063] Specific implementation method eight: combination Figure 1 To describe this embodiment, the attack angle adjustment drive component of this embodiment includes a worm wheel 10, a worm 11, a handle 12, a steering assembly 13, and a worm mounting seat 14. The worm wheel 10 is fixedly mounted on the circumferential wall of the outer side of the inner disk 3, the worm mounting seat 14 is mounted on the inner shell 1, the worm 11 is rotatably mounted on the worm mounting seat 14, the steering assembly 13 is mounted on one end of the worm 11, the handle 12 is connected to the steering assembly 13, and the handle 12 drives the worm 11 to rotate after being turned by the steering assembly 13, and the worm 11 is engaged with the worm wheel 10.

[0064] With this arrangement, the angle-of-attack adjustment driver primarily drives the rotation of the inner and outer discs 3 and 4. Since the air inlet passage is fixed, when the rotation angles of the inner and outer discs 3 and 4 change, the airflow impacts the cascade blades at different locations, thereby enabling testing at different angles of attack. The remaining structure and components are identical to any of the first to fourth embodiments.

[0065] In this embodiment, the worm gear 10 uses one-third or one-half of the worm gear strips and is mounted on the inner casing 1 near the air inlet side. In other words, the rotation angle of the cascade test piece is preferably 30°-90°, which can meet the requirements of most angle of attack tests.

[0066] The steering assembly 13 of this embodiment preferably adopts the form of a bevel gear set to achieve steering. The structure is simple and the steering is stable, which is more suitable for high temperature environments.

[0067] This embodiment uses a handle as the driving force instead of a motor or other forms. One reason is that the high temperature environment during the test is taken into consideration, and the motor working at high temperature is prone to adverse effects. The other reason is that manual control can adjust the rotation angle at any time.

[0068] Specific implementation method nine: Combination Figure 6 To illustrate this embodiment, the upper baffle assembly of this embodiment includes an upper retractable wall panel 15, a rotating connection 16, an upper lifting connection 17 and an upper nut screw pair 18. One end of the upper retractable wall panel 15 is rotatably mounted on the upper positioning block 6 through the rotating connection 16, the upper nut screw pair 18 is mounted on the inner shell 1, and the screw end of the upper nut screw pair 18 is connected to the other end of the upper retractable wall panel 15 through the upper lifting connection 17.

[0069] This arrangement primarily serves to raise and lower the upper retractable panel 15. When raised, it prevents interference with the cascade test piece during installation. When lowered, it abuts the upper portion of the cascade test piece after installation, further securing the cascade. Other components and connections are the same as those in any of the first to third embodiments.

[0070] This embodiment uses an upper nut screw pair 18 to connect the end of the upper contraction wall plate 15, so that the blade can maintain its position and state unchanged when it is impacted by airflow, thereby achieving self-locking.

[0071] Specific implementation method ten: Combination Figure 6 To illustrate this embodiment, the lower baffle assembly of this embodiment includes a lower shrinkage wall panel 19, two lifting supports 20, a lower lifting connection member 21 and a lower nut screw pair 22. The curved portion of the lower shrinkage wall panel 19 is fitted with the end of the lower positioning block 7 and installed on the inner shell 1, and the lower end of the horizontal portion of the lower shrinkage wall panel 19 is connected to the lower nut screw pair 22 installed on the inner shell 1 through the lower lifting connection member 21. The two lifting supports 20 are respectively installed on the curved portion and the lower end of the horizontal portion of the lower shrinkage wall panel 19.

[0072] This arrangement facilitates the downward movement of the lower retractable wall plate 19 to hold the cascade test piece. Other components and connection relationships are the same as those in any one of the specific embodiments 1 to 6.

[0073] Specific implementation method 11: Combination Figure 6 and Figure 8 To illustrate this embodiment, the diameter of the channel formed between the upper contraction wall plate 15 and the lower contraction wall plate 19 is gradually reduced from the air inlet side.

[0074] This arrangement ensures and simulates the airflow entering the cascade test piece to conform to the actual situation of the model by contracting the intake airflow. The other components are the same as any one of the specific embodiments 1 to 7.

[0075] As a preferred embodiment, the air flow channel in this embodiment has a constant diameter near the cascade test piece, that is, the upper contraction wall panel 15 and the lower contraction wall panel 19 are arranged in parallel.

[0076] Specific implementation method 12: Combination Figure 8 To illustrate this embodiment, the lifting support member 20 of this embodiment includes a bracket 20-1, a slide rail 20-2 and a slider 20-3. The slide rail 20-2 is installed obliquely on the inner shell 1, and the slider 20-3 is slidably installed on the slide rail 20-2. One end of the bracket 20-1 is connected to the slider 20-3, and the other end of the bracket 20-1 is connected to the lower retractable wall panel 19.

[0077] This arrangement facilitates the support of the lower shrinkage wall panel 19, and the lower shrinkage wall panel 19 is smooth and does not get stuck during the lifting and lowering process. The other components are the same as any one of the specific embodiments 1 to 8.

[0078] Furthermore, the slide rail 20 - 2 in this embodiment is installed on the inner shell 1 at an angle of 45°, which matches the structural shape of the lower shrinkage wall panel 19 to ensure that no deviation occurs during the lifting and lowering process of the lower shrinkage wall panel 19.

[0079] Specific implementation method 13: Combination Figure 7 To explain this embodiment, this embodiment further includes a four-degree-of-freedom displacement mechanism 23 , which is mounted on the outer surface of the outer shell 2 .

[0080] Such an arrangement facilitates the accurate movement of the disc mechanism of the present invention to the test position for air intake. The other components are the same as any one of the specific embodiments 1 to 9.

[0081] The structure inside the test chamber of this embodiment can be disassembled according to the test requirements, including the nozzle section and test section after the contraction section, to provide a three-dimensional space for simulating high-altitude aircraft under low Reynolds number conditions; at the same time, the contraction section can also be designed into a plane and a fan-shaped structure according to the test requirements, thereby realizing plane blade cascade tests and fan-shaped blade cascade tests.

[0082] Specific implementation method 14: Combination Figure 4 To illustrate this embodiment, the secondary flow system C of this embodiment includes an air compressor C-31, a dryer C-32, a gas tank C-33, a first switch valve C-34, a first regulating valve C-35 and a flow meter C-36. The air compressor C-31, the dryer C-32, the gas tank C-33, the first switch valve C-34, the first regulating valve C-35 and the flow meter C-36 are connected in sequence.

[0083] Such an arrangement facilitates the introduction of airflow into the test section. The other components are the same as any one of the specific embodiments 1 to 9.

[0084] Specific implementation method 15: Combination Figure 4 To illustrate this embodiment, the secondary flow system C in this embodiment also includes an electrical system E, a test system F, a video monitoring system G, auxiliary process equipment H and a cooling water system I.

[0085] The electrical system E, test system F, video surveillance system G, and auxiliary process equipment H are electrically connected to the air intake system A, wind tunnel body B, and secondary flow system C, respectively. The cooling water system I is connected to the exhaust system D.

[0086] This arrangement facilitates the control of the entire wind tunnel test. The other components are the same as any one of the specific embodiments 1 to 9.

[0087] Specific implementation method 16: Combination Figure 4 To illustrate this embodiment, the exhaust system D of this embodiment includes a second expansion joint D-41, a heat exchanger D-42, a plurality of second on-off valves D-43 and a plurality of vacuum pumps D-44.

[0088] Multiple second switch valves D-43 are connected in parallel, and each second switch valve D-43 is connected to a vacuum pump D-44. The second expansion joint D-41 and the heat exchanger D-42 are connected and then connected to the multiple second switch valves D-43 arranged in parallel.

[0089] This arrangement facilitates exhaust. Other components are the same as any one of the specific embodiments 1 to 9.

[0090] Combine Figures 1 to 11 To illustrate the working principle of the present invention:

[0091] According to the test requirements, the cascade test can consider the influence of secondary flow, that is, the mixing test of cooling air (secondary flow) and mainstream flow, as well as the study of the cooling effect of cooling air flow on turbine blades. The layout of the secondary flow system is as follows: Figure 1 As shown, its structure includes an air compressor, a dryer, a pressure-surge tank, a switch valve, a regulating valve and a flow meter.

[0092] The airflow passing through the experimental chamber is discharged into the exhaust system. If a high-temperature test is being conducted, the incoming airflow needs to be cooled by heat exchange until it reaches the working range of the vacuum pump. The vacuum pump can then be used for suction work; the heat exchanger D-42 uses water cooling for heat exchange.

[0093] Test system F mainly includes conventional test systems and specialized test systems. The conventional test system mainly includes air path pressure and temperature measurement. The measured parameters provide the test basis for adjusting the wind tunnel test conditions. The specialized test system is mainly determined by the test requirements of the test section, such as related flow field testing, heat transfer testing, optical testing, etc.

[0094] The control system of the wind tunnel test bench (video monitoring system G) is mainly composed of the blade performance analysis system, the suction unit control system, the valve control system, the displacement mechanism remote control system, the actuator (electrically controlled switch valve, electronically controlled regulating valve, motion controller, displacement mechanism, stepper motor), and the measurement sensor (analog pressure sensor, grating ruler, etc.). The overall architecture of the control system is shown in the figure below. Figure 9 shown.

[0095] The measurement signal sent by the measuring sensor is processed by the corresponding acquisition module or measuring instrument and converted into an engineering value and displayed on the computer; at the same time, the test status value is output manually or automatically through the computer operation interface, and the output signal of the control board is used to drive the corresponding electrical actuator, so that the actuator completes the corresponding action to achieve the test requirement state.

[0096] The "Suction Unit Control System" enables safe and smooth startup and shutdown of the unit.

[0097] The "valve control system" automatically or manually controls the electronically controlled switch valves and electronically controlled regulating valves of the test equipment's air supply pipeline, air extraction pipeline, bypass air intake pipeline according to the test status, so as to achieve the air pressure state required for the tester's suction test and air-cooled mixing test.

[0098] The "displacement mechanism proximal control system" controls the four-degree-of-freedom displacement mechanism, controlling the probe's position and attitude to measure the flow field at the test piece's outlet and the boundary layer at the test piece's inlet. The four-degree-of-freedom displacement mechanism includes three linear degrees of freedom (X, Y, and Z directions) and one α angular degree of freedom about the Z direction.

[0099] When the inlet size of the test section is 90 mm × 300 mm, the inlet is throttled, the inlet pressure of the test piece is 10 kPa, the temperature is heated to 800 K, and the maximum mass flow rate is 3.3 kg / s, the relationship between the inlet flow rate of the test piece and the Mach number is as follows: Figure 10 As shown in the figure, when the inlet pressure is 10kPa and the temperature is 800K, the maximum mass flow rate is 0.33kg / s; when the cascade test aspect ratio is 2, the cascade chord length is 50mm, and the inlet temperature is 800K, the relationship between the incoming flow Mach number and the Reynolds number is as follows: Figure 11 As shown in the figure, when the Mach number is 0.7, the maximum Reynolds number is 1.6953×10 4 .

[0100] Assembly of the cascade test piece:

[0101] Blade-shaped holes are opened on the upper mounting plate and the lower mounting plate, and a plurality of blade cascades are sequentially mounted in the blade-shaped holes on the upper mounting plate and the lower mounting plate from top to bottom to form a blade cascade to be tested.

[0102] Installation of cascade test piece:

[0103] The cascade test piece is installed in the rectangular holes of the inner and outer disks by bolts.

[0104] Adjustment of the attack angle of the cascade test piece:

[0105] When the angle of attack needs to be adjusted for cascade testing, the handle is turned. After the steering assembly turns, the worm is driven to rotate, the worm drives the worm wheel to rotate, and the worm wheel drives the inner and outer discs to rotate at the same time. Since the cascade test piece is installed on the inner and outer discs, the angle of attack of the cascade test piece can be changed by rotating the worm wheel while keeping the direction of the inlet airflow unchanged.

[0106] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A temperature-controllable open low-Reynolds number intelligent wind tunnel, characterized by: It includes the air intake system (A), the wind tunnel body (B), the secondary flow system (C) and the exhaust system (D). The air intake system (A) includes an air intake device (A-11), a main air intake regulating valve (A-12), an auxiliary air intake regulating valve (A-13), an air intake heater (A-14), and a first expansion joint (A-15). The air intake device (A-11) is connected to the air intake heater (A-14) through the main air intake regulating valve (A-12) and the auxiliary air intake regulating valve (A-13) arranged in parallel. The air flow drawn from the atmosphere by the air intake device (A-11) is heated by the air intake heater (A-14) and then enters the first expansion joint (A-15). The first expansion joint (A-15) is connected to the wind tunnel body (B). The secondary flow system (C) is connected to the test chamber (B-23) in the wind tunnel body (B). The exhaust system (D) is connected to the exhaust side of the test chamber (B-23). The wind tunnel body (B) consists of a diffuser section (B-21), a stabilizer section (B-22), and a test chamber (B-23). ​​The diffuser section (B-21), stabilizer section (B-22), and test chamber (B-23) are connected in sequence from left to right. The test chamber (B-23) consists of a convergent section (B-24), a nozzle section (B-25), and a test chamber (B-26). The convergent section (B-24), nozzle section (B-25), and test chamber (B-26) are connected in sequence from left to right. The test section (B-26) includes an inner shell (1), an outer shell (2), a positioning block assembly, a plurality of connection limiters, an inner disc (3), an outer disc (4), an angle of attack adjustment drive, an upper baffle assembly, and a lower baffle assembly; the inner shell (1) and the outer shell (2) are connected via a plurality of connection limiters, the positioning block assembly is mounted on the air inlet side of the inner shell (1) and the outer shell (2), one end of the upper baffle assembly is rotatably connected to the positioning block assembly, and is used to be clamped on the blade of the blade to be tested. The lower baffle assembly is slidably matched with the side of the positioning block assembly and moves up and down, and is used to The inner disc (3) and the outer disc (4) are respectively rotatably mounted on the inner shell (1) and the outer shell (2), and rectangular holes (5) are respectively opened on the inner disc (3) and the outer disc (4), wherein the cascade test piece is mounted in the rectangular hole (5), and scales are engraved on the outer side of the inner shell (1) to measure the rotation angles of the inner disc (3) and the outer disc (4), and an angle of attack adjustment driving member is mounted on the outer side of the inner disc (3), and the angle of attack adjustment driving member drives the inner disc (3) and the outer disc (4) to rotate simultaneously, thereby realizing a change in the angle of attack of the cascade test piece; The secondary flow system (C) includes an air compressor (C-31), a dryer (C-32), a gas tank (C-33), a first on-off valve (C-34), a first regulating valve (C-35), and a flow meter (C-36). The air compressor (C-31), the dryer (C-32), the gas tank (C-33), the first on-off valve (C-34), the first regulating valve (C-35), and the flow meter (C-36) are connected in sequence. The exhaust system (D) includes a second expansion joint (D-41), a heat exchanger (D-42), a plurality of second switching valves (D-43) and a plurality of vacuum pumps (D-44). A plurality of second switch valves (D-43) are connected in parallel, each second switch valve (D-43) is connected to a vacuum pump (D-44), and the second expansion joint (D-41) and the heat exchanger (D-42) are connected to the plurality of second switch valves (D-43) arranged in parallel.

2. The temperature-controllable open low-Reynolds number intelligent wind tunnel according to claim 1, characterized in that: The air intake system (A) further includes a flow guide device (A-16) and an air intake duct (A-17), wherein the flow guide device (A-16) and the air intake duct (A-17) are installed between the air intake device (A-11) and the main air intake regulating valve (A-12); The guide device (A-16) includes a conical shell and a metal mesh, the conical shell is connected to the air intake pipe (A-17) in sequence, and the metal mesh is installed at the large end of the conical shell, wherein the metal mesh includes an outer metal mesh and an inner metal mesh, and the outer metal mesh and the inner metal mesh are installed in sequence at the large end of the conical shell.

3. The temperature-controllable open low-Reynolds number intelligent wind tunnel according to claim 2, characterized in that: The positioning block assembly comprises an upper positioning block (6) and a lower positioning block (7), wherein the upper positioning block (6) and the lower positioning block (7) are fixedly mounted on the air inlet side of the inner shell (1) and the outer shell (2), and the upper positioning block (6) and the lower positioning block (7) are arranged in parallel.

4. The temperature-controllable open low-Reynolds number intelligent wind tunnel according to claim 3, characterized in that: The end of the lower positioning block (7) is provided with a 45° bevel.

5. The temperature-controllable open low-Reynolds number intelligent wind tunnel according to claim 4, characterized in that: The connection limiter comprises a distance sleeve (8) and a bolt (9). The bolt (9) passes through the outer shell (2) and is inserted into the distance sleeve (8) between the inner shell (1) and the outer shell (2), and extends out of the inner shell (1) and is then mounted on the inner shell (1) through a nut.

6. The temperature-controllable open low-Reynolds number intelligent wind tunnel according to claim 5, characterized in that: It also includes electrical system (E), test system (F), video surveillance system (G), auxiliary process equipment (H) and cooling water system (I), The electrical system (E), test system (F), video monitoring system (G) and auxiliary process equipment (H) are electrically connected to the air intake system (A), wind tunnel body (B) and secondary flow system (C), respectively. The cooling water system (I) is connected to the exhaust system (D).

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