Semi-open type heat protection device for wind tunnel test and heat protection method

Abstract

The invention relates to a semi-open type heat-proof device for a wind tunnel test and a heat-proof method, a heat-proof cover of the device is fixedly connected to the end part of a supporting tool arm, one side of the supporting tool arm is connected to a fixed sealing cover through two guide rails, a cylinder rod of an oil cylinder is fixedly connected to the other side of the supporting tool arm, and a cylinder body of a high-speed oil cylinder is fixedly connected to the fixed sealing cover; the fixed sealing cover is fixedly connected to the test cabin, an oil supply port of the hydraulic driving system penetrates through the fixed sealing cover through an oil supply pipe to be connected with an oil port in one end of the oil cylinder, an oil return port of the hydraulic driving system penetrates through the fixed sealing cover through an oil return pipe to be connected with an oil port in the other end of the high-speed oil cylinder, and a hydraulic servo valve of the hydraulic driving system switches the oil supply direction and the oil return direction. The control module is used for controlling cylinder rods of the high-speed oil cylinders to extend and retract; the heat shield is used for being put into a flow field to prevent high-temperature airflow from flowing through a wind tunnel model area, heating of local areas of the upper surfaces and the lower surfaces of the test model and the force measuring balance and the area close to the supporting tool arm side is avoided, and the heating degree of the local area of the test model close to the open face of the heat shield is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of wind tunnel tests and relates to a semi-open heat protection device and a heat protection method for wind tunnel tests. Background Art

[0002] The semi-open heat protection device and heat protection method for wind tunnel test involved in the present invention are a heat protection system for testing models and force balances in low total pressure, high total temperature and pure gas medium wind tunnels. The operation of this type of wind tunnel test is mainly divided into three stages: the first stage is the wind tunnel pressure and temperature adjustment stage, which is mainly to obtain airflow with stable pressure and temperature; the second stage is the wind tunnel test stage, which is to obtain effective model measurement data; the third stage is the deflation stage at the end of the test, which is to discharge the high-temperature gas in the heater cavity after the test. This type of wind tunnel adopts graphite resistance heating technology to obtain a high-temperature pure gas test medium above 1000K. The temperature and pressure adjustment stage lasts for tens of seconds; at the same time, the total temperature of the restricted airflow is too high, and a high-temperature stop valve and an independent exhaust path cannot be set downstream of the heater. After the test, the high-temperature airflow in the heater cavity can only be discharged through the nozzle, test section, and exhaust equipment path in sequence, and the deflation stage lasts for several minutes. In these two stages, the high-temperature airflow will flow through the wind tunnel test section, which will have a serious impact on the measurement accuracy and effectiveness of the force test system in the test section. The low total pressure of this type of wind tunnel results in low static pressure in the flow field, that is, below 10Pa. The boundary layer in the nozzle grows significantly, resulting in a small uniform area of ​​the wind tunnel flow field, about Φ100mm. When conducting force measurement tests, due to the small size of the wind tunnel flow field and low static pressure, the force load is small, the force balance (within Φ10mm in diameter) and the model (within Φ50mm in diameter) are small in size, and the beam unit of the force balance (within 1mm) is even smaller in size. Because the model and the force balance are very small, it is difficult to use sufficient conventional heat protection measures between the two, such as water cooling and insulation layers. The force balance is severely heated during the temperature and pressure adjustment stage and the air release stage, and there is a large temperature drift effect, which may even directly cause the force balance to be damaged and fail, directly affecting the accuracy and effectiveness of the wind tunnel force measurement test.

[0003] In conventional wind tunnels with high total pressure, moderate total temperature and pure gas medium, the total temperature is moderate, below 800K, and metal heating technology is generally used. Due to the high total pressure, the static pressure of the flow field is high, about 100Pa or more, the surface layer in the nozzle grows slowly, and the flow field size is large, reaching Φ300mm or more. In such conventional wind tunnels, force measurement tests are carried out because the wind tunnel flow field size is large and the static pressure is high, and the force measurement load is large. The force measurement balance and model size are large, and the beam unit size of the force measurement balance is moderate. Sufficient conventional heat protection measures (water cooling, heat insulation) can usually be used between the model and the force measurement balance, and combined with the heat protection method of the launch-type angle of attack mechanism, the temperature drift and effectiveness problems of the force measurement test caused by high-temperature airflow can be solved. The heat protection method based on the drop-type angle-of-attack mechanism in a conventional wind tunnel is as follows: during the temperature and pressure adjustment stage, the model and the force balance are withdrawn from the flow field through the drop-type angle-of-attack mechanism, so that the model and the force balance are not in the high-temperature airflow, thereby preventing the model and the force balance from being heated; after the pressure and temperature are stable, the wind tunnel starts the force measurement test, and the model and the force balance are quickly dropped into the flow field through the drop-type angle-of-attack mechanism, and then the force measurement test is carried out within the effective start-up time of the wind tunnel; during the deflation stage after the test, the model and the force balance are withdrawn from the flow field again through the drop-type angle-of-attack mechanism, so that the model and the force balance are not in the high-temperature airflow, thereby preventing the model and the force balance from being heated.

[0004] In a low total pressure, high total temperature, pure gas medium wind tunnel, because the force measurement model and force measurement balance are small in size, if a fast-release angle of attack mechanism (on the order of 500mm / s) is used for heat protection, the fast release and fast stop process will cause strong vibration of the model and force measurement balance, which will directly damage the tiny beam unit of the force measurement balance. If a slow-release angle of attack mechanism (on the order of 50mm / s) is used for heat protection, the release and withdrawal time will be on the order of 10s, which will greatly reduce the effective force measurement test time of the wind tunnel, and vibration damage to the small force measurement balance will also be unavoidable. Summary of the invention

[0005] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art, to provide a semi-open heat protection device and a heat protection method for wind tunnel tests, to reduce the force measurement temperature drift effect caused by high temperature airflow in low total pressure, high total temperature, pure gas medium wind tunnel tests, to improve the force measurement test accuracy, and to solve the problem of small force measuring balances being damaged and failing due to continuous heating or vibration.

[0006] The solution to the technical problem of the present invention is: a semi-open heat protection device for wind tunnel test, the heat protection device comprises a heat protection cover, a support knife arm, an oil cylinder, a fixed sealing cover, and a hydraulic drive system;

[0007] The heat shield is fixedly connected to the end of the support blade arm, one side of the support blade arm is connected to the fixed sealing cover through two heavy-duty guide rails, the cylinder rod is fixedly connected to the other side of the support blade arm, the cylinder body of the high-speed cylinder is fixedly connected to the fixed sealing cover, the fixed sealing cover is fixedly connected to the test cabin, the oil supply port of the hydraulic drive system passes through the fixed sealing cover through the oil supply pipe and is connected to the oil port at one end of the cylinder, the oil return port of the hydraulic drive system passes through the fixed sealing cover through the oil return pipe and is connected to the oil port at the other end of the high-speed cylinder, the hydraulic servo valve of the hydraulic drive system switches the oil supply and return directions, and is used to control the extension and retraction of the cylinder rod of the high-speed cylinder, so as to realize the deployment and withdrawal of the support blade arm and the heat shield; the fixed sealing cover realizes the vacuum sealing of the test section;

[0008] The heat shield is used to be placed in the flow field to prevent high-temperature airflow from flowing through the wind tunnel model area, to avoid heating of the upper and lower surfaces of the test model and the force measuring balance and the area close to the supporting blade arm, and to reduce the degree of heating in the local area of ​​the test model close to the open surface of the heat shield.

[0009] Preferably, the heat shield is a semi-open structure of beam + thin shell.

[0010] Preferably, the overall shape of the heat shield wraps the test model area, the upper and lower surfaces of the heat shield are both rectangular flat plate structures, the two are symmetrical and parallel to the horizontal plane, the part of the heat shield close to the nozzle is the front part, the front surface of the heat shield is spliced ​​by two upper and lower rectangular flat plate structures to form a wedge structure with a certain angle, and the vertical cross-section aerodynamic shape of the entire heat shield is a wedge + rectangular aerodynamic shape.

[0011] Preferably, the included angle of the wedge structure is ≤50°.

[0012] Preferably, the side of the heat shield close to the supporting blade arm is a flat plate structure spliced ​​by a front triangular flat plate and a rear rectangular flat plate, so that the upper surface, lower surface, front surface and side of the heat shield close to the supporting blade arm are fully enclosed, preventing airflow from passing through this part and flowing through the model area, while avoiding collision between the heat shield and the model during the deployment and withdrawal process.

[0013] Preferably, a triangular flat plate is provided at the front portion of the side surface of the heat shield opposite to the supporting blade arm, and the rear portion is an open space. Two sides of the triangular flat plate are respectively connected to the upper and lower surface edges of the heat shield, and a gap is provided between the third side and the front edge of the model area to reduce the amount of airflow bypassing the model area from this side, and to avoid collision between the heat shield and the model during the deployment and withdrawal process.

[0014] Preferably, a rectangular flat plate structure is provided on the rear end face of the heat shield near the supporting blade arm side, the rectangular flat plate structure is connected to the upper surface, the lower surface and the edge of the side flat plate structure near the supporting blade arm of the heat shield, and the other side of the rear end face away from the supporting blade arm is open, so as to reduce the depth of the airflow flowing through the model area from the open side of the heat shield, and at the same time avoid the collision between the heat shield and the model support rod during the deployment and withdrawal process.

[0015] Preferably, a certain gap is set between the front end of the heat shield and the nozzle outlet plane, preferably 50 mm.

[0016] Preferably, in the horizontal section, its aerodynamic shape when viewed from above is a rectangular structure, the gap between the inner net space boundary of the heat shield close to the supporting blade arm and the model area is ≥50mm, and the outer edge of the heat shield opposite to the supporting blade arm protrudes from the model area 4 by ≥20mm; in the vertical section, a gap is reserved between the inner net space boundary of the heat shield and the model area, and the gap is ≥50mm.

[0017] A semi-open heat protection method for wind tunnel testing using the above heat protection device comprises the following steps:

[0018] S1, test preparation stage, the wind tunnel test model is supported in the center of the flow field through the angle of attack mechanism, and the wind tunnel test model is adjusted to a 0° angle of attack attitude, and then the heat shield is dropped into the flow field to protect the wind tunnel test model and the force balance;

[0019] S2, temperature and pressure adjustment stage, start to adjust the pressure regulating valve, the cold airflow passes through the pressure regulating valve and heater, obtains high-temperature airflow at the nozzle inlet, and then expands through the nozzle to accelerate and flow into the test section area. The airflow is diverted through the heat shield to bypass the model area and flow to the downstream super expansion section for discharge;

[0020] S3. After the temperature and pressure of the nozzle inlet airflow are stable, remove the heat shield from the nozzle flow field area, observe the pressure changes in the test cabin, and after confirming that the flow field is quickly established, carry out the force measurement test;

[0021] S4. After the test, the model is adjusted to a 0° angle of attack through the angle of attack mechanism, the heat shield is dropped into the flow field, the pressure regulating valve is closed, and the high-temperature airflow inside the heater cavity flows into the test section through the nozzle, and then bypasses the model area through the upper and lower diversions of the heat shield, and flows to the downstream super-expansion section for discharge.

[0022] The beneficial effects of the present invention compared with the prior art are:

[0023] (1) The semi-open heat protection device proposed in the present invention adopts a specially designed semi-open heat protection shield structure, and optimizes the heat protection shield wedge angle, the gap between the inner net space boundary of the heat protection shield and the model area, the gap between the front end of the heat protection shield and the nozzle outlet, the heat protection shield material, the heat protection shield delivery speed and other heat protection device parameters, so as to prevent the high-temperature airflow from flowing through the model area during the temperature and pressure adjustment stage and the post-test venting stage of the low total pressure, high total temperature, pure gas medium wind tunnel, avoid the high-temperature airflow from continuously heating the model and the force measuring balance, reduce the temperature drift effect of the force measuring balance, and avoid the force measuring balance from being damaged due to continuous heat, thereby improving the accuracy and effectiveness of the force measuring test; at the same time, avoid the collision between the heat protection shield and the test model during the delivery and withdrawal process.

[0024] (2) The heat protection method of release protection-withdrawal test-re-release protection proposed in the present invention replaces the existing heat protection method of withdrawal protection-release test-re-withdrawal protection based on the release-type angle of attack mechanism, avoids the rapid release-withdrawal behavior of the model and the force measuring balance, solves the inherent problem of damage to the tiny beam unit of the small force measuring balance due to vibration induced by the release-type angle of attack mechanism, and improves the effectiveness of the force measuring test. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A top view of a heat protection device system for wind tunnel testing according to an embodiment of the present invention (withdrawn outside the flow field);

[0026] Figure 2 This is a front view of a heat protection device system for wind tunnel testing according to an embodiment of the present invention;

[0027] Figure 3 This is a top view of a heat protection device system for wind tunnel testing according to an embodiment of the present invention (placed in a flow field). DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the embodiments.

[0029] The present invention aims to design a semi-open heat protection device and a heat protection method, so as to avoid continuous heating of the model and the force measuring balance during the temperature and pressure adjustment stage and the deflation stage after the test, reduce the temperature drift effect of the force measuring balance, and solve the problem of continuous heat damage to the force measuring balance; at the same time, the angle of attack mechanism does not adopt a launching method, so as to avoid the rapid launching and withdrawal of the model and the force measuring balance during the test, and solve the problem of vibration damage of the small force measuring balance due to launching.

[0030] like Figures 1 to 3As shown, the semi-open heat protection device provided by the present invention is composed of a heat protection cover 6, a support knife arm 7, a high-speed oil cylinder 8, a fixed sealing cover 9, and a hydraulic drive system 10. The heat protection cover 6 is fixedly connected to the end of the support knife arm 7 by bolts, one side (for example, the lower surface) of the support knife arm 7 is connected to the fixed sealing cover 9 by two heavy-duty guide rails, the cylinder rod of the high-speed oil cylinder 8 is fixedly connected to the other side (for example, the upper surface) of the support knife arm 7 by an adapter, the cylinder body of the high-speed oil cylinder 8 is fixedly connected to the fixed sealing cover 9 by an adapter, and the fixed sealing cover 9 is fixedly connected to the test cabin 2 by bolts, the oil supply port of the hydraulic drive system 10 is connected to the oil port at one end of the high-speed oil cylinder through the oil supply pipe passing through the fixed sealing cover 9, and the oil return port of the hydraulic drive system 10 is connected to the oil port at the other end of the high-speed oil cylinder through the oil return pipe passing through the fixed sealing cover 9. The hydraulic servo valve of the hydraulic drive system 10 switches the oil supply and return directions, and then controls the extension and retraction of the cylinder rod of the high-speed cylinder 8 to achieve the deployment and withdrawal of the support knife arm 7 and the heat shield 6; the vacuum sealing of the test section is achieved by fixing the sealing cover 9.

[0031] The overall shape of the heat shield 6 wraps the test model area 4, and is a semi-open structure of beam + thin shell. The upper and lower surfaces of the heat shield 6 are both rectangular flat plate structures, which are symmetrical and parallel to the horizontal plane. The part of the heat shield 6 close to the nozzle 1 is the front part. The front surface of the heat shield 6 is a splicing of two upper and lower rectangular flat plate structures to form a wedge structure with a certain angle. The vertical cross-section aerodynamic shape of the entire heat shield 6 is a wedge + rectangular aerodynamic shape. The angle of the wedge structure is ≤50°.

[0032] The side of the heat shield 6 close to the support blade arm is a flat plate structure composed of a front triangular flat plate and a rear rectangular flat plate, so that the upper surface, lower surface, front surface and side of the heat shield close to the support blade arm are fully enclosed, preventing airflow from flowing through this part and flowing through the model area, and at the same time avoiding the heat shield from colliding with the wind tunnel test model 5 during the deployment and withdrawal process;

[0033] The side of the heat shield 6 opposite to the support blade arm is provided with a triangular flat plate only at the front side, and the rear side is an open space, the two sides of the triangular flat plate are respectively connected to the edges of the upper and lower rectangular flat plates on the front surface of the heat shield 6, and a gap is provided between the third side and the front edge of the model area, so that the side opposite to the support blade arm is a partially open plane with a closed front, reducing the air flow bypassing the model area from this side, and avoiding the collision between the heat shield and the model during the launch-withdrawal process;

[0034] The rear end face of the heat shield 6 is a rectangular flat plate structure near the support blade arm side, the upper and lower sides of the rectangular flat plate structure are respectively connected to the upper and lower surface flat plate structures of the heat shield 6, one side of the rectangular flat plate structure is connected to the side flat plate structure near the support blade arm, and the other side of the rectangular flat plate structure is a certain gap away from the center of the model area, so that the tail plane is a partially open plane, reducing the depth of the airflow bypassing the model area from the open side of the heat shield, and avoiding the collision between the heat shield and the model support rod during the launch-withdrawal process. In addition, the overall shape of the heat shield wraps the test model area.

[0035] When the heat shield is placed in the flow field, the structure of the heat shield can prevent the high-temperature airflow from flowing through the model area 4, avoiding heating of the main areas of the upper and lower surfaces of the model and the force balance and the areas close to the supporting knife arm side, and reducing the heating degree of the local area of ​​the test side model close to the open surface of the heat shield, thereby reducing the temperature drift effect of the force balance, and solving the problem of continuous heat damage to the model and the force balance, thereby improving the accuracy and effectiveness of the force measurement test.

[0036] This aerodynamic configuration is more conducive to achieving the self-guiding of the heat shield, reducing the thermal load on the leading edge of the heat shield and avoiding self-overheating damage; at the same time, the guided high-temperature airflow deviates from the model area and is discharged to the super-expansion section 3 at the rear in the form of up and down split flows, thereby reducing the local thermal load on the test model close to the open side of the heat shield, reducing the temperature drift effect of the force balance due to heating, solving the problem of continuous heat damage to the model and the force balance, and improving the accuracy and effectiveness of the force measurement test.

[0037] In the vertical section, there should be enough clearance between the inner clear space boundary of the heat shield and the model area, preferably ≥50mm. When the support blade arm + heat shield vibrates during rapid launch, avoid the heat shield from hitting the test model to prevent damage to the model and force balance.

[0038] In horizontal section, its aerodynamic shape when viewed from above is a rectangular structure, the clearance between the inner net space boundary near the support blade arm 7 and the model area is ≥50mm, and the outer edge of the heat shield opposite to the support blade arm 7 protrudes from the model area 4 by ≥20mm. This setting can effectively reduce the heat load borne by the local part of the test model near the open side of the heat shield, reduce the temperature drift effect of the force balance due to heating, solve the problem of continuous heat damage to the model and the force balance, and improve the accuracy and effectiveness of the force test.

[0039] A certain gap is set between the front end of the heat shield and the outlet plane of the nozzle 1, preferably 50 mm. This setting can effectively prevent the heat shield from colliding with the nozzle when the heat shield is quickly deployed; this setting can reduce the blocking effect of the heat shield with a large blockage degree on the nozzle flow to a certain extent.

[0040] The heat shield is made of lightweight high-strength aluminum alloy. The density of this material is about 1 / 3 of that of stainless steel, which reduces the weight load of the heat shield and then reduces the vibration amplitude of the support blade arm + heat shield induced by rapid launch, avoiding the heat shield from hitting the test model due to excessive amplitude, causing damage to the model and force balance.

[0041] The release speed of the heat shield driven by the high-speed cylinder is set to 200mm / s. This speed is moderate, which can reduce the vibration amplitude of the support blade arm + heat shield induced by the rapid release, prevent the heat shield from hitting the test model due to excessive amplitude, and prevent the cylinder rod of the high-speed cylinder from damaging its internal sliding seal due to excessive amplitude.

[0042] The wind tunnel test heat protection method based on the semi-open heat protection device provided by the present invention is as follows: in the test preparation stage, the wind tunnel test model is supported at the center of the flow field by the angle of attack mechanism, and the wind tunnel test model is adjusted to a 0° angle of attack posture, and then the heat protection cover is put into the flow field to protect the wind tunnel test model and the force balance, such as Figure 3 ; In the temperature and pressure adjustment stage, the pressure regulating valve is adjusted. The cold airflow passes through the pressure regulating valve and the heater, and obtains a high-temperature airflow at the nozzle inlet. Then it expands and accelerates into the test section through the nozzle. The main airflow is diverted by the heat shield to bypass the model area and flow to the downstream super expansion section for discharge, so as to avoid continuous heating of the model and the force balance, reduce the temperature drift effect of the force balance, and improve the accuracy of the force measurement test. After the temperature and pressure of the airflow at the nozzle inlet are stable, the heat shield is withdrawn from the nozzle flow field area. Figure 1 Observe the pressure change in the test chamber, and after confirming that the flow field is quickly established, use the angle of attack mechanism, model support rod 11, force balance 12, model, etc. to carry out force measurement test; the angle of attack mechanism includes turbine 13, worm 14 and drive device 15. After the test, adjust the model to 0° angle of attack posture again through the angle of attack mechanism, put the heat shield into the flow field, close the pressure regulating valve, and the high-temperature airflow inside the heater cavity flows into the test section through the nozzle, and then bypasses the model area through the upper and lower diversions of the heat shield, and flows to the downstream super expansion section for discharge. In the deflation stage, the high-temperature airflow in the test section flow field is prevented from continuously heating the model and the force balance, so as to prevent the force balance from being damaged due to overheating and affecting the effectiveness of the force measurement test. The use of this heat protection method can effectively prevent the model and the force balance from being continuously heated during the temperature and pressure adjustment stage and the air release stage, reduce the temperature drift effect of the force balance, avoid damage to the force balance due to continuous heating, and improve the accuracy and effectiveness of the force measurement test; at the same time, the use of this heat protection method can avoid the rapid deployment and withdrawal of the model and the force balance, and can avoid the inherent problem of damage to the tiny beam unit of the small force balance due to vibration induced by the deployment angle of attack mechanism, thereby improving the effectiveness of the force measurement test.

[0043] In summary, the semi-open heat protection device and the heat protection method proposed in the present invention adopt a semi-open heat shield structure of "upper and lower surfaces, front surface, and side surface close to the support blade arm are fully closed surfaces, the side surface opposite to the support blade arm is a partially open plane closed in the front, the tail surface is a partially open plane closed near the support blade arm side, and the front is a wedge aerodynamic shape", and the heat protection device parameters such as the wedge angle of the heat shield, the gap between the inner net space boundary of the heat shield and the model area, the gap between the front end of the heat shield and the nozzle outlet, the heat shield material, and the heat shield delivery speed are optimized. In the temperature and pressure adjustment stage and the deflation stage, the high-temperature airflow bypasses the model area to avoid the high-temperature airflow from continuously heating the model and the force balance, and at the same time, the vibration of the support blade arm and the heat shield is reduced to avoid the heat shield from damaging the model and the force balance during the delivery and withdrawal process, thereby improving the accuracy and effectiveness of the force measurement test. A heat protection method based on a semi-open heat protection device for deployment protection, withdrawal test, and re-deployment protection is adopted to avoid the rapid deployment and withdrawal behavior of the model and the force balance in the heat protection method based on the deployment angle attack mechanism, solve the inherent problem of damage to the tiny beam unit of the small force balance due to vibration induced by the deployment angle attack mechanism, and improve the effectiveness of the force measurement test.

[0044] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A semi-open heat protection device for wind tunnel testing, characterized in that: It comprises a heat shield (6), a supporting blade arm (7), an oil cylinder (8), a fixed sealing cover (9), and a hydraulic drive system (10); The heat shield (6) is fixedly connected to the end of the support blade arm (7), one side of the support blade arm (7) is connected to the fixed sealing cover (9) through two heavy-duty guide rails, the cylinder rod of the oil cylinder (8) is fixedly connected to the other side of the support blade arm (7), the cylinder body of the high-speed oil cylinder (8) is fixedly connected to the fixed sealing cover (9), the fixed sealing cover (9) is fixedly connected to the test cabin, the oil supply port of the hydraulic drive system (10) is connected to the oil port at one end of the oil cylinder through the oil supply pipe passing through the fixed sealing cover (9), the oil return port of the hydraulic drive system (10) is connected to the oil port at the other end of the high-speed oil cylinder through the oil return pipe passing through the fixed sealing cover (9), the hydraulic servo valve of the hydraulic drive system (10) switches the oil supply and return directions, and is used to control the extension and retraction of the cylinder rod of the high-speed oil cylinder (8), so as to realize the deployment and withdrawal of the support blade arm (7) and the heat shield (6); the fixed sealing cover (9) realizes the vacuum sealing of the test section; The heat shield is used to be placed in the flow field to prevent high-temperature airflow from flowing through the wind tunnel model area (4), thereby preventing the upper surface and lower surface local areas of the test model and the force balance and the area close to the supporting blade arm from being heated, and reducing the degree of heating of the local area of ​​the test model close to the open surface of the heat shield.

2. A semi-open heat protection device for wind tunnel testing according to claim 1, characterized in that: The heat shield (6) is a semi-open structure of beam + thin shell.

3. A semi-open heat protection device for wind tunnel testing according to claim 2, characterized in that: The overall shape of the heat shield wraps the test model area, the upper and lower surfaces of the heat shield (6) are both rectangular flat plate structures, the two are symmetrical and parallel to the horizontal plane, the part of the heat shield (6) close to the nozzle is the front part, the front surface of the heat shield (6) is spliced ​​by two upper and lower rectangular flat plate structures to form a wedge structure with a certain angle, and the vertical cross-section aerodynamic shape of the entire heat shield (6) is a wedge + rectangular aerodynamic shape.

4. A semi-open heat protection device for wind tunnel testing according to claim 4, characterized in that: The included angle of the wedge structure is ≤50°.

5. A semi-open heat protection device for wind tunnel testing according to claim 4, characterized in that: The side surface of the heat shield (6) close to the supporting blade arm is a flat plate structure formed by splicing a front triangular flat plate and a rear rectangular flat plate, so that the upper surface, the lower surface, the front surface and the side surface close to the supporting blade arm of the heat shield are fully enclosed, thereby preventing airflow from flowing through this part and passing through the model area, and at the same time avoiding collision between the heat shield and the model during the deployment and withdrawal process.

6. A semi-open heat protection device for wind tunnel testing according to claim 4, characterized in that: A triangular flat plate is arranged at the front side of the side opposite to the supporting blade arm of the heat shield (6), and the rear side is an open space. Two sides of the triangular flat plate are respectively connected to the upper and lower surface edges of the heat shield (6), and a gap is arranged between the third side and the front edge of the model area to reduce the amount of airflow bypassing the model area from this side, and to avoid collision between the heat shield and the model during the delivery and withdrawal process.

7. A semi-open heat protection device for wind tunnel testing according to claim 4, characterized in that: A rectangular flat plate structure is arranged on the rear end face of the heat shield (6) near the support blade arm side, and the rectangular flat plate structure is connected to the upper surface, the lower surface, and the edge of the side flat plate structure near the support blade arm of the heat shield (6). The other side of the rear end face away from the support blade arm is open, so as to reduce the depth of the airflow bypassing the model area from the open side of the heat shield, and at the same time avoid the heat shield from colliding with the model support rod during the launch and withdrawal process.

8. A semi-open heat protection device for wind tunnel testing according to claim 1, characterized in that: A certain gap is set between the front end of the heat shield and the nozzle outlet plane, preferably 50mm.

9. A semi-open heat protection device for wind tunnel testing according to claim 1, characterized in that: In the horizontal section, the aerodynamic shape when viewed from above is a rectangular structure, the clearance between the inner clear space boundary of the heat shield near the support blade arm (7) and the model area is ≥50mm, and the outer edge of the heat shield opposite to the support blade arm (7) protrudes from the model area 4 by ≥20mm; in the vertical section, a clearance is reserved between the inner clear space boundary of the heat shield and the model area, and the clearance is ≥50mm, so as to avoid collision between the heat shield and the model support rod during the deployment and withdrawal process.

10. A semi-open heat protection method for wind tunnel testing using the heat protection device according to any one of claims 1 to 9, characterized in that The steps include: S1, test preparation stage, the wind tunnel test model is supported in the center of the flow field through the angle of attack mechanism, and the wind tunnel test model is adjusted to a 0° angle of attack attitude, and then the heat shield is dropped into the flow field to protect the wind tunnel test model and the force balance; S2, temperature and pressure adjustment stage, start to adjust the pressure regulating valve, the cold airflow passes through the pressure regulating valve and heater, obtains high-temperature airflow at the nozzle inlet, and then expands through the nozzle to accelerate and flow into the test section area. The airflow is diverted through the heat shield to bypass the model area and flow to the downstream super expansion section for discharge; S3. After the temperature and pressure of the nozzle inlet airflow are stable, remove the heat shield from the nozzle flow field area, observe the pressure changes in the test cabin, and after confirming that the flow field is quickly established, carry out the force measurement test; S4. After the test, the model is adjusted to a 0° angle of attack through the angle of attack mechanism, the heat shield is dropped into the flow field, the pressure regulating valve is closed, and the high-temperature airflow inside the heater cavity flows into the test section through the nozzle, and then bypasses the model area through the upper and lower diversions of the heat shield, and flows to the downstream super-expansion section for discharge.

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