A secondary sealing system and method for passive ejection high altitude simulation test

Abstract

The application relates to a secondary sealing system and method for passive ejection high-altitude simulation test. The system comprises a test cabin, a diffuser, a sealing cover, a pulley assembly, a pneumatic execution structure, a gas supply system and a constant tension system. The test cabin and the diffuser are connected through flange bolts; the diffuser is connected with the sealing cover through a pin shaft; the sealing cover is connected with the diffuser through the pin shaft; a pulley assembly support rod is welded at a proper position near the ground of the high-altitude simulation test bed to ensure the fixation of the pulley assembly; the pneumatic execution structure is connected with the diffuser through a hinge bolt; a gas cylinder is connected with the pneumatic cylinder through a high-pressure gas pipe; a steel wire rope in the constant tension system is connected with a tension sensor and passes through a pulley sealing assembly and is connected with a connecting hole in the sealing cover. The application realizes the performance, structure and reliability examination of a double-pulse solid rocket engine during ignition under the high-altitude environment state by using the passive ejection technology, and expands the passive ejection high-altitude simulation test bed capacity.

Description

Technical Field

[0001] This invention relates to a dual-pulse solid rocket engine for high-altitude environment simulation tests, specifically to a secondary sealing system and method for passive ejection high-altitude simulation tests. Background Technology

[0002] Traditional solid rocket engines load propellant into a single combustion chamber, and upon ignition, all the propellant burns completely, producing only one thrust. In contrast, dual-pulse engines utilize a split mechanism to divide the engine casing into two combustion chambers, each loaded with propellant. By igniting the two chambers in series, a single engine can generate two thrusts, thereby extending missile range and increasing flight speed during the terminal guidance phase. To evaluate the ballistic performance and structural reliability of dual-pulse solid rocket engines during high-altitude flight, high-altitude simulation tests are necessary.

[0003] Currently, high-altitude simulation tests of dual-pulse solid rocket engines generally use active ejection tests. The principle is that, in addition to the pressurization and ejection effect of the exhaust diffuser, an external exhaust suction system is connected in series at the outlet of the exhaust diffuser to continuously pressurize the mixture of gas, air or steam discharged from the diffuser before venting it into the atmosphere. With the addition of the exhaust suction system, the low-pressure environment in the test chamber can be controlled throughout the test.

[0004] Research on high-altitude environment simulation testing technology for engines began both domestically and internationally in the 1970s. Based on differences in structure and ejection method, high-altitude environment simulation testing for solid rocket engines is divided into passive ejection and active ejection. The "engine + gas diffuser" type, also known as a passive ejection high-altitude environment simulation test bench, uses the supersonic jet ejected from the engine as the power source for ejection. The "engine + gas diffuser + external extraction system" type is called an active ejection high-altitude environment simulation test bench, which adds an external extraction system to the passive ejection system. Due to the differences in structure and ejection method, the two types of test benches differ significantly in system composition, construction scale, operational performance, and testing capabilities. Passive ejection high-altitude model test benches were widely used in early engine high-altitude model tests, but due to their limitations, active ejection high-altitude model test benches are generally used for high-altitude model tests of advanced solid rocket engines such as dual-pulse solid rocket engines and attitude control engines. However, due to the high investment cost, expensive testing fees, long testing cycle, and complex testing process of active ejection high-altitude environment simulation test rigs, there are few active ejection test rigs in China capable of conducting high-thrust, high-flow solid rocket engine high-altitude environment simulation tests, which cannot meet the needs of rapid model development.

[0005] When conducting high-altitude environment simulation tests on dual-pulse solid rocket engines, active ejection high-altitude simulation test stands are generally used. However, active ejection high-altitude simulation test stands have complex structures, long test cycles, and high costs per test. Traditional passive ejection high-altitude simulation test stands, which only use a "pump + diffuser" exhaust method without an external exhaust extraction system, require the test chamber to be sealed and isolated from the outside air environment before establishing a high-altitude low-pressure environment. After the engine finishes firing, outside air rapidly flows back into the test chamber through the diffuser, and the test chamber no longer has a low-pressure environment. Dual-pulse solid rocket engines, on the other hand, are filled with two separate propellant units in the combustion chamber, and each part of the propellant is burned separately at arbitrary timing. If a passive ejection high-altitude simulation test stand is used for the ignition test of a dual-pulse solid rocket engine, the diffuser will not operate between the two ignitions, causing outside air to enter the test chamber through the diffuser, connecting the outside with the test chamber. When subsequent pulse ignition occurs, a high-altitude low-pressure environment cannot be achieved inside the test chamber. Meanwhile, the complex test bench environment during the ignition gap is caused by the continuous flow of cooling water within the diffuser, the high-temperature erosion of the diffuser by the combustion gases, and the presence of unexpelled toxic gases. Manually sealing the diffuser at close range during the ignition gap poses a safety hazard. Therefore, to address the technical challenge of traditional passive ejector high-altitude simulation test benches being unable to establish multiple high-altitude low-pressure environments in a single test and to improve test safety, this invention proposes a secondary sealing method for passive ejector high-altitude simulation tests. This method enables the passive ejector high-altitude simulation test bench to achieve multiple pressurizations of the test chamber in a single test through remote operation. Summary of the Invention

[0006] The technical problem to be solved by the present invention

[0007] This invention proposes a secondary sealing method for passive ejection high-altitude simulation tests to solve the problem that passive ejection high-model test benches cannot continuously simulate high-altitude low-pressure environments in multiple cycles during a single test.

[0008] The technical solution adopted by this invention to solve the technical problem

[0009] A secondary sealing system for passive ejection high-altitude simulation experiments, comprising:

[0010] The test chamber provides a sealed environment for the engine, ensuring that the engine is in a high-altitude, low-pressure environment.

[0011] The diffuser is connected to the test chamber by flange bolts, with the mating surface sealed, and together with the engine installed in the chamber, it forms an ejection system.

[0012] The sealing plug is connected to the diffuser via a pin. A curved rod is welded to the sealing plug, and a positioning step is set at one end of the sealing surface to ensure the coaxiality of the plug and the diffuser and to reduce the radial displacement between the plug and the diffuser during the stress process.

[0013] The pulley assembly is used for changing the direction of the wire rope, ensuring that the wire rope changes direction smoothly three times during operation. The pulley assembly support rod is welded at an appropriate position near the ground of the high-altitude simulation test platform to ensure that the pulley assembly is firmly fixed during operation.

[0014] The pneumatic actuator consists of a support rod, a cylinder, a crank, and a spherical bearing. The cylinder is connected to the support rod and the crank via the spherical bearing. The pneumatic actuator is connected to the diffuser via a hinge bolt.

[0015] The gas supply system consists of a nitrogen cylinder, a pressure reducing valve, a high-pressure gas pipe, a three-way adapter, and a pressure sensor. The outlet of the high-pressure nitrogen cylinder is connected to the pressure reducing valve, and the high-pressure gas pipe is connected in sequence. A three-way adapter is added in the pipeline for installing the pressure sensor. The cylinder of the pneumatic actuator is connected to the nitrogen cylinder through the high-pressure gas pipe.

[0016] The constant tension system includes a tension sensor and a tension system. The tension system consists of a spring steel belt fixed by a reel, the end of which is connected to a steel wire rope. The steel wire rope is connected to the tension sensor and passes through a pulley sealing assembly, connecting to the connection hole of the sealing plug.

[0017] Furthermore, an O-ring seal is provided at the connection between the sealing plug and the diffuser.

[0018] Furthermore, the O-ring material is F111 fluororubber.

[0019] Furthermore, the contact surface between the sealing plug and the diffuser outlet is a double rectangular sealing structure.

[0020] Furthermore, the crank of the pneumatic actuator also includes a limiting rod.

[0021] Furthermore, the sealing plug is made of carbon structural steel.

[0022] A secondary sealing method for passive ejection high-altitude simulation experiments, the operation steps are as follows:

[0023] S1: Connect, assemble and fix the sealing plug, pulley assembly, pneumatic actuator and constant tension system according to the connection method. Before the test, the sealing plug should be in the open state.

[0024] S2: Set the outlet pressure on the pneumatic actuator pressure reducing valve according to the selected cylinder model;

[0025] S3: Calculate the required tension based on the designed length of the crank arm of the sealing plug, and input the tension value into the constant tension system;

[0026] S4: Pneumatic constant tension system, close the sealing plug;

[0027] S5: Start the vacuum pump on the high-altitude simulation test bench to evacuate the test chamber. After reaching the predetermined requirements, maintain the pressure for no less than 30 minutes and check the sealing of the test chamber. If there is leakage, check the system and re-evacuate to check the sealing.

[0028] S6: Before officially conducting the high-altitude simulation test of the solid rocket engine, the engine will first be installed, adjusted, and fixed inside the test chamber;

[0029] S7: With the sealing plug of the present invention in the open state, after the engine 1 pulse ignition is completed, start the constant tension system and close the sealing plug;

[0030] S8: Start the vacuum pump on the test bench to evacuate air and complete the secondary vacuuming of the high-altitude test chamber.

[0031] Furthermore, the pulley assembly includes a support rod and two sets of fixed pulleys, enabling adjustment in four degrees of freedom. This method achieves wire rope direction adjustment through three sets of this pulley assembly.

[0032] Furthermore, the tension sensor is a TDE1 type tension sensor with a nonlinearity error of ±0.1%FS and a sensitivity of ±0.05mV / V.

[0033] Beneficial effects obtained by the present invention

[0034] This invention addresses the problem that the test chamber of a passive ejection high-altitude simulation test bench cannot achieve multiple pressurizations in a single test. It proposes a secondary sealing method for passive ejection high-altitude simulation tests, which achieves a sealed environment in the test chamber during the ignition gap of the dual-pulse solid rocket engine. The test chamber is then pressurized twice by evacuating and depressurizing the sealed test chamber using a vacuum pump.

[0035] This invention effectively enhances the capabilities of the passive ejection high-altitude simulation test bench. Traditional passive ejection high-altitude simulation test benches can only conduct high-altitude simulation tests of single-chamber solid rocket engines, which cannot meet the needs of solid rocket engine technology development. This invention improves the testing capabilities of the passive ejection high-altitude simulation test bench, creating favorable hardware conditions for thrust testing and specific impulse evaluation of dual-pulse solid rocket engines.

[0036] This invention effectively reduces the fixed investment cost of experimental equipment, shortens the experimental cycle, and lowers experimental expenses. Compared to passive ejection high-altitude simulation test benches, active ejection test benches have higher investment costs, longer experimental cycles, and higher experimental expenses. This has constrained the progress of solid rocket engine technology development and increased development costs. This invention realizes the feasibility of conducting high-altitude simulation tests of dual-pulse solid rocket engines on a passive ejection test bench, effectively ensuring the needs of future solid rocket engine development. Attached Figure Description

[0037] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0038] Figure 1 Flowchart of external pressure test for pressure vessel heads;

[0039] Figure 2 : Schematic diagram of external pressure test scheme for pressure vessel head;

[0040] Figure 3 : Schematic diagram of the sealing plug structure;

[0041] Figure 4 : Schematic diagram of the sealing principle of the plug and diffuser;

[0042] Figure 5 Schematic diagram of pulley assembly structure;

[0043] Figure 6 : Simplified diagram of the force analysis of the sealing plug;

[0044] Figure 7 Schematic diagram of a pneumatic actuator;

[0045] Figure 8 Schematic diagram of a constant tension system;

[0046] The components are as follows: 1-Test chamber, 2-Diffuser, 3-Pneumatic actuator, 4-Water cooling system, 5-Plug, 6-First pulley assembly, 7-Second pulley assembly, 8-Wire rope, 9-Tension sensor, 10-Constant tension system, 11-Air supply pipeline, 12-T-connector, 13-Air source, 14-Pressure acquisition system, 15-Constant tension system, 16-Support rod, 17-Pulley, 18-Pulley, 31-Support rod, 32-Cylinder, 33-Spherical bearing, 34-Crank, 35-Limit rod, 51-O-ring, 52-Pre-drilled bolt hole, 53-Positioning step, 54-Diffuser outlet section component, 101-Spring steel belt, 102-Roller, 103-Wire rope, 104-Tension sensor. Detailed Implementation

[0047] This invention utilizes the lever principle and employs an axial sealing method with a sealing ring. A constant tension system applies force to the plug, and a tension monitoring system monitors the steel wire rope tension in real time, causing the sealing ring to compress and deform within the sealing groove. To ensure sealing reliability, a pneumatic actuator is designed above the plug to apply secondary force. A tee adapter is connected to the pipeline, and an external pressure sensor is connected to monitor the pipeline pressure in real time. Once a predetermined value is reached, the force application stops, thus achieving a secondary seal in the test chamber. The vacuum equipment on the test bench is activated to evacuate the test chamber, achieving a vacuum environment that meets the test requirements. Then, the steel wire rope tension is released, the cylinder is retracted, and the plug is fixed to the diffuser outlet face under the influence of atmospheric pressure difference. The test procedure of this invention is as follows: Figure 1 As shown.

[0048] To make the objectives, features, and advantages of the technical solution proposed in this invention more apparent and understandable, the embodiments of the technical solution proposed in this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the proposed technical solution, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0049] The specific scheme of this method is as follows: Figure 2 As shown, before the first pulse ignition of the dual-pulse solid rocket engine, a plug is installed at the diffuser outlet, a pulley assembly is fixed, and a pneumatic cylinder is connected to a pre-designed and machined fixing seat for the diffuser inlet water collection ring. A pneumatic actuator is installed directly above the diffuser outlet. A steel wire rope and high-pressure air pipe are connected. Pressure sensors are calibrated, and pressure sensors, tension sensors, and a data acquisition and monitoring system are connected. The outlet pressure value of the pressure reducing valve at the air source is preset. To reduce the impact of the plug's rotation under the action of the combustion gas on the water cooling system, industrial wool felt is adhered and fixed to the impact-prone parts of the water cooling system. The main components of this invention include: an experimental chamber, a diffuser, a sealing plug, a pulley assembly, a pneumatic actuator, an air supply system, and a constant tension system.

[0050] Test Chamber

[0051] The test chamber is primarily used to provide a sealed environment for the engine, ensuring it operates in a high-altitude, low-pressure environment. The test chamber should have pre-drilled flange connection holes for connection and fixation to the diffuser.

[0052] diffuser

[0053] The diffuser docks with the test chamber via pre-drilled flange bolt holes, and the docking surface is designed to be sealed. Together with the engine installed in the chamber, it forms an ejector system. Through the specific profile of the diffuser and the thermal protection scheme, the required high-altitude low-pressure environment at the nozzle outlet and inside the vacuum test chamber is maintained while ensuring the smooth discharge of exhaust gases, thus achieving the purpose of high-altitude simulation testing.

[0054] Sealing plug

[0055] As a key component, the sealing plug is made of high-quality carbon structural steel, with a curved rod welded to it. Due to the long weld, post-weld heat treatment is performed to reduce deformation of the plug, and the sealing surface undergoes secondary machining to ensure its flatness. Additionally, a positioning step is designed at one end of the sealing surface to ensure the coaxiality of the plug and diffuser, and to reduce radial displacement between them under stress, thus minimizing shear stress on the O-ring. The sealing plug structure is as follows... Figure 3 As shown. To ensure a reliable seal between the sealing plug and the diffuser, an O-ring seal is used. The O-ring material is F111 fluororubber. Due to the good self-tightening sealing effect of the double rectangular seal structure, a double rectangular seal structure is designed and machined on the contact surface between the plug and the diffuser outlet, as shown in the figure. Figure 4 As shown. The design value for the ratio A of the area of ​​the sealing groove to the area of ​​the O-ring is 1.1 to 1.4, and the formula is:

[0056]

[0057] Where: h—width of the sealing groove, unit: mm;

[0058] b—Depth of the sealing groove, in mm;

[0059] d—Diameter of the sealing ring, unit: mm.

[0060] The initial compression ε of the O-ring is designed to be 28%–35%, and the formula is as follows:

[0061]

[0062] Where: δ0—the difference between the O-ring diameter and the sealing groove depth, in mm;

[0063] d—Depth of sealing groove, unit: mm.

[0064] pulley assembly

[0065] The pulley assembly is mainly used for changing the direction of the wire rope, ensuring smooth three-way direction changes during operation. This method uses three sets of pulley assemblies to achieve wire rope direction adjustment. The pulley assembly includes a support rod and two sets of fixed pulleys, enabling adjustment in four degrees of freedom. The pulley assembly structure is as follows: Figure 5 As shown.

[0066] pneumatic actuator

[0067] Pneumatic actuators mainly consist of a support rod, cylinder, crank, limit rod, and spherical bearing, etc., specifically as follows: Figure 6 As shown. When the pneumatic actuator is not working, the cylinder piston rod retracts, the crank rotates counterclockwise around the shaft, the crank separates from the plug, and the plug is not subjected to the force of the crank. When the pneumatic actuator is performing machining work, the cylinder piston rod extends out of the cylinder chamber, and the crank acts on the plug. The cylinder structure is a double-acting cylinder, and the specific selection mainly depends on the pressure exerted on the plug by the crank structure. The crank force analysis can be based on... Figure 5 The force analysis diagram is used for calculation. The formula for calculating the cylinder pressure p is:

[0068]

[0069] Where: F—the given design value of the force on the plug;

[0070] r — cylinder bore.

[0071] Gas supply system

[0072] This method uses a high-pressure nitrogen cylinder as the gas source. A pressure reducing valve is connected to the outlet of the high-pressure nitrogen cylinder to reduce the pressure of the outflowing nitrogen and control the inlet pressure of the gasbag. A high-pressure gas hose is used for the gas pipeline, and a T-connector is added to the pipeline for installing a pressure sensor.

[0073] Constant tension system

[0074] To ensure the stability of the force value on the sealing plug and keep the sealing ring in a stable and reliable compressed state, a constant tension system is used for control. The constant tension system mainly consists of a tension sensor and a tension system. The tension sensor selected is a TDE1 type, with a nonlinearity error of ±0.1%FS and a sensitivity of ±0.05mV / V. The specific measurement range is mainly based on the curved rod structure on the plug. After simplifying the plug model, a force analysis is performed. Based on the principle of torque balance, its simplified force diagram is as follows... Figure 5 As shown, the pressure F2 generated by the tension of the steel wire rope on the plug is:

[0075]

[0076] Where: F1 is the tension of the wire rope;

[0077] l1—Lever arm length of the wire rope;

[0078] l2—Length of the pressure arm of the plug.

[0079] The key to the tension system lies in the constant-tension spring. In its free state, all the spring steel strips of this spring are tightly compressed together, and any segment of the spring steel strip has the same radius of deflection in the free state. A simplified structural diagram of a constant-tension spring is shown below. Figure 7 As shown. Because the sealing ring generates a reverse elastic force on the sealing can cap when compressed and deformed, a braking mechanism must be designed into the constant tension system. When starting the constant tension system, the displacement of the wire rope during the time period from the start of the tension reading to the set tension value should be measured to ensure that the sealing cap is not affected by the constant tension system when it opens.

[0080] In specific connection, the test chamber and diffuser are connected by flange bolts; the diffuser is designed with pin holes during the design and manufacturing stage to mate with the pin connection hole of the sealing plug, and the sealing plug is connected to the diffuser through the pin; the pulley assembly support rod is welded at an appropriate position near the ground of the high-altitude simulation test platform to ensure that the pulley assembly is firmly fixed during operation; the connection between the pneumatic actuator and the diffuser mainly relies on the interface reserved on the diffuser and is connected by hinge bolts; the cylinder and nitrogen cylinder are connected through a high-pressure gas pipe; the steel wire rope in the constant tension system is first connected to the tension sensor, and then passes through the pulley sealing assembly and is connected to the connection hole of the sealing plug.

[0081] The following description, in conjunction with the appendix of the present invention, Figure 1 The process flow clearly and completely describes the technical solution implemented in this invention:

[0082] Step 1: Connect, assemble, and fix the sealing plug, pulley assembly, pneumatic actuator, and constant tension system according to the connection method. Before the test, the sealing plug should be in the open position.

[0083] Step 2: Set the outlet pressure on the pneumatic actuator pressure reducing valve according to the selected cylinder model;

[0084] Step 3: Calculate the required tension based on the designed length of the crank arm of the sealing plug, and input the tension value into the constant tension system;

[0085] Step 4: Close the sealing plug of the pneumatic constant tension system;

[0086] Step 5: Start the vacuum pump on the high-altitude simulation test bench to evacuate the test chamber. After reaching the predetermined requirements, maintain the pressure for no less than 30 minutes and check the sealing of the test chamber. If there is leakage, check the system and re-evacuate to check the sealing.

[0087] Step 6: Before formally conducting the high-altitude simulation test of the solid rocket engine, the engine is first installed, adjusted, and fixed inside the test chamber;

[0088] Step 7: With the sealing plug of the present invention in the open state, after the engine 1 pulse ignition is completed, start the constant tension system and close the sealing plug;

[0089] Step 8: Start the vacuum pump on the test bench to evacuate the air and complete the secondary vacuuming of the high-altitude test chamber.

[0090] This invention enables the performance, structure, and reliability assessment of a dual-pulse solid rocket engine during ignition under simulated high-altitude conditions using passive ejection technology. It expands the capabilities of the passive ejection high-altitude simulation test stand and provides a new technical approach for high-altitude environment simulation testing of dual-pulse solid rocket engines.

[0091] The design method of this patent was applied to conduct experiments and tests in a scaled-down high-altitude simulation test of a solid rocket engine, successfully achieving secondary sealing of the test chamber. The key parameters such as thrust and pressure measured in the experiment met the requirements of the test mission, and the total impulse of the solid rocket engine reached the design specifications. In summary, the method proposed in this invention is feasible.

Claims

1. A secondary sealing method for a passive ejection high-altitude simulation test, characterized in that, The operating steps are as follows: S1: Connect, assemble and fix the sealing plug, pulley assembly, pneumatic actuator and constant tension system according to the connection method, and keep the sealing plug in the open state before the test; S2: Set the outlet pressure on the pneumatic actuator pressure reducing valve according to the selected cylinder model; S3: Calculate the required tension based on the designed length of the crank arm of the sealing plug, and input the tension value into the constant tension system; S4: Activate the constant tension system and close the sealing plug; S 5: Start the vacuum pump on the high-altitude simulation test bench to evacuate the test chamber. After reaching the predetermined requirements, maintain the pressure for no less than 30 minutes and check the sealing of the test chamber. If there is leakage, check the system and evacuate again to check the sealing. S6: Before officially conducting the high-altitude simulation test of the solid rocket engine, the engine was first installed, adjusted, and fixed inside the test chamber; S7: With the sealing plug in the open state, after the engine pulse ignition is completed, start the constant tension system and close the sealing plug; S8: Start the vacuum pump on the test bench to evacuate air and complete the secondary vacuuming of the high-altitude test chamber. This method employs a secondary sealing system for passive ejection high-altitude simulation experiments, comprising: The test chamber provides a sealed environment for the engine, ensuring that the engine operates in a high-altitude, low-pressure environment. The diffuser is connected to the test chamber by flange bolts, with the mating surface sealed, and together with the engine installed in the chamber, it forms an ejection system. The sealing plug is connected to the diffuser via a pin. A curved rod is welded to the sealing plug, and a positioning step is set at one end of the sealing surface to ensure the coaxiality of the plug and the diffuser and to reduce the radial displacement between the plug and the diffuser during the stress process. The pulley assembly is used for changing the direction of the wire rope, ensuring that the wire rope changes direction smoothly three times during operation. The pulley assembly support rod is welded at an appropriate position near the ground of the high-altitude simulation test platform to ensure that the pulley assembly is firmly fixed during operation. The pneumatic actuator consists of a support rod, a cylinder, a crank, and a spherical bearing. The cylinder is connected to the support rod and the crank via the spherical bearing. The pneumatic actuator is connected to the diffuser via a hinge bolt. When the pneumatic actuator is working, the cylinder piston rod pushes out of the cylinder chamber, and the crank acts on the plug, applying a secondary force to the plug. The gas supply system consists of a nitrogen cylinder, a pressure reducing valve, a high-pressure gas pipe, a three-way adapter, and a pressure sensor. The outlet of the high-pressure nitrogen cylinder is connected to the pressure reducing valve, which is connected to the high-pressure gas pipe. A three-way adapter is added to the pipeline for installing the pressure sensor. The cylinder of the pneumatic actuator is connected to the nitrogen cylinder through the high-pressure gas pipe. The constant tension system includes a tension sensor and a tension system. The tension system consists of a spring steel belt fixed by a reel, the end of which is connected to a steel wire rope. The steel wire rope is connected to the tension sensor and passes through a pulley sealing assembly to be connected to the connection hole of the sealing plug. The constant tension system is used to apply force to the plug. The sealing plug and the diffuser outlet contact surface have a double rectangular sealing structure.

2. The secondary sealing method for a passive ejection high-altitude simulation test according to claim 1, characterized in that: The pulley assembly includes a support rod and two sets of fixed pulleys, enabling adjustment in four degrees of freedom.

3. The secondary sealing method for a passive ejection high-altitude simulation test according to claim 1, characterized in that: The tension sensor used is a TDE1 type tension sensor with a nonlinearity error of ±0.1%FS and a sensitivity of ±0.05mV / V.

4. The secondary sealing method for a passive ejection high-altitude simulation test according to claim 1, characterized in that: An O-ring seal is provided at the connection between the sealing plug and the diffuser.

5. A secondary sealing method for a passive ejection high-altitude simulation test according to claim 4, characterized in that: The O-ring is made of F111 fluororubber.

6. The secondary sealing method for a passive ejection high-altitude simulation test according to claim 1, characterized in that: The crank of the pneumatic actuator also includes a limit rod.

7. A secondary sealing method for a passive ejection high-altitude simulation test according to claim 4, characterized in that: The sealing plug is made of carbon structural steel.

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