A capping plug for an engine nozzle, a method of manufacture, a test apparatus and a test method

Abstract

This invention provides an engine nozzle plug, its manufacturing method, testing apparatus, and testing method. The plug includes a pressure-bearing body, an adhesive layer, and an elastic transition layer for bonding to the expansion section of the engine nozzle. The pressure-bearing body includes a bottom and a support portion. The support portion is a rotating body with a gradually increasing diameter from one end to the other. One end of the support portion is connected to the bottom, and the other end is a free end. The adhesive layer is located on the outer surface of the support portion, and the transition layer is bonded to the support portion through the adhesive layer. The pressure-bearing body is made of metal. This invention solves the problem that existing engine nozzle plugs cannot simultaneously possess good reverse pressure-bearing capacity, forward opening, and sealing functions.

Description

Technical Field

[0001] This invention relates to the field of aerospace engine nozzle plug testing technology, and particularly to an engine nozzle plug, its manufacturing method, testing apparatus, and testing method. Background Technology

[0002] A rocket engine consists of main components such as propellant grains, a combustion chamber shell, a nozzle, and an ignition device. The nozzle, connected to the combustion chamber shell, is the energy conversion device of the rocket engine, converting the chemical energy generated by the combustion of the propellant grains into kinetic energy to provide power for the engine.

[0003] The nozzle consists of three parts: a converging section, a throat liner, and a diverging section. Its inner surface serves as a combustion gas passage, boosting the combustion gases in the combustion chamber to subsonic, sonic, and even supersonic speeds. The nozzle cap is a crucial component, performing the following functions: 1) sealing the engine combustion chamber, providing moisture and dust protection; 2) providing an instantaneous sealed environment for the engine, establishing ignition pressure, shortening ignition delay time, and ensuring reliable ignition. If the cap opens under low pressure, the ignition delay results in significant propellant energy loss, potentially leading to engine stall; if the cap opens under high pressure, the initial ignition pressure peak is excessively high, potentially causing an engine explosion.

[0004] However, for special engines, the engine needs to be ejected from the launch canister before ignition. Therefore, the nozzle plug also needs to have a reverse pressure-bearing function. That is, when the engine is ejected from the launch canister, the nozzle plug's own structural strength resists the aerodynamic force generated by the launch device, creating a reverse force to propel the engine. Generally, nozzle plugs are of two types: flexible and metal, both located in the nozzle's convergent section. Flexible plugs are molded from nylon fabric with the strength and sealing properties of rubber, primarily using nylon fabric for strength. Metal plugs rely on a designed annular thinning area to set the opening pressure. Both solutions have sealing and forward opening functions, but lack reverse pressure-bearing capabilities. Therefore, it is necessary to develop an engine nozzle plug with reverse pressure-bearing capabilities, a manufacturing method, a testing device, and a testing method to ensure that the nozzle plug has good reverse pressure-bearing capacity, forward opening, and sealing functions. Summary of the Invention

[0005] The purpose of this invention is to provide an engine nozzle plug, a manufacturing method, a testing device, and a testing method to solve the problem that existing engine nozzle plugs cannot simultaneously possess good reverse pressure resistance, forward opening, and sealing functions.

[0006] To solve the above-mentioned technical problems, the present invention provides a plug for an engine nozzle, comprising a pressure-bearing body, an adhesive layer, and an elastic transition layer for bonding with the expansion section of the engine nozzle. The pressure-bearing body includes a bottom and a support portion. The support portion is a rotating body with a diameter that gradually increases from one end to the other. One end of the support portion is connected to the bottom, and the other end of the support portion is a free end. The adhesive layer is located on the outer surface of the support portion, and the transition layer is bonded to the support portion through the adhesive layer. The pressure-bearing body is made of metal.

[0007] Optionally, the process includes: fabricating a pressure-bearing body; applying an adhesive to the outer surface of the support portion of the pressure-bearing body and one side of the annular member, bonding the annular member to the outer surface of the support portion, and curing it to form an adhesive layer between the support portion and the annular member; and cutting the annular member, cutting off the portion of the annular member that extends beyond the support portion to ensure that the annular area of ​​the cut annular member is consistent with the bonding area of ​​the support portion, so as to form a transition layer.

[0008] The present invention also provides a test device for the above-mentioned engine nozzle plug, comprising: a base, a core ring, and a top seat. The top seat has an air inlet. The top seat is sealed and mounted on the base, and a working cavity is formed between the base and the top seat. The working cavity communicates with the air inlet. A stepped hole is formed on the end face of the base near the working cavity. The core ring is mounted on the stepped surface of the stepped hole. The core ring and the hole wall of the stepped hole are connected by static sealing putty. The inner wall shape and size of the core ring are the same as the expansion section of the engine nozzle. The inner wall of the core ring is bonded to the transition layer of the engine nozzle plug by an adhesive. One end of the inner cavity of the core ring communicates with the working cavity, and the other end of the inner cavity of the core ring communicates with the stepped hole.

[0009] Optionally, the core ring includes an inner layer and an outer layer, the inner layer is disposed inside the outer layer, and the outer layer mates with the inner wall of the stepped hole of the base, and the transition layer of the inner layer and the plug of the engine nozzle are bonded together with an adhesive.

[0010] Optionally, the core ring is made by impregnation and winding, wherein the inner layer is a carbon fiber tape layer and the outer layer is a high-silica tape layer.

[0011] Optionally, the core ring is flush with the end of the stepped hole near the working cavity.

[0012] Optionally, the diameter of the smaller section of the stepped hole gradually increases from the end closer to the working cavity to the end farther away from the working cavity.

[0013] Optionally, when the core ring is installed, if the end of the inner wall of the core ring with a smaller diameter is closer to the working cavity than the end with a larger diameter, the end of the segment with a smaller diameter in the stepped hole smoothly transitions to the inner wall of the core ring, and the diameter of the segment with a smaller diameter in the stepped hole is greater than or equal to the diameter of the end of the core ring away from the working cavity.

[0014] The present invention also provides a test method for testing the above-mentioned test apparatus for engine nozzle plugs, comprising: The engine nozzle cap is test-installed on the inner wall of the core ring so that the shape of the support part matches the shape of the inner wall of the core ring. The bonding surface position is marked on the inner wall of the core ring, and then the bonding surface is treated. Apply adhesive to the transition layer of the engine nozzle plug, then bond the engine nozzle plug to the inner wall of the core ring and cure it. Perform one of the following tests: forward sealing test, forward opening test, and reverse pressure test: The positive sealing test includes: The core ring is installed on the stepped surface of the stepped hole using static sealing putty, so that the core ring is installed on the stepped surface in a first direction, and the smaller diameter end of the inner wall of the core ring is positioned away from the base, to simulate the forward installation posture of the engine nozzle expansion section. The top mount is installed on the base, and the top mount and the base form a working cavity. Gas is introduced into the working chamber at a predetermined time and a first pressure, and the sealing performance of the engine nozzle plug is measured. The forward opening test includes: The core ring is installed on the stepped surface of the stepped hole using static sealing putty, so that the core ring is installed on the stepped surface in a first direction, and the smaller diameter end of the inner wall of the core ring is positioned away from the base, to simulate the forward installation posture of the engine nozzle expansion section. The top mount is installed on the base, and the top mount and the base form a working cavity. Gas is introduced into the working chamber at a second pressure, and the pressure at which the plug of the engine nozzle is opened in the forward direction is measured. The reverse bearing test includes: The core ring is installed on the step surface of the stepped hole using static sealing putty, so that the core ring is installed on the step surface in a second direction, and the larger diameter end of the inner wall of the core ring is set away from the base to simulate a reverse pressure posture. The top seat is mounted on the base, and the top seat and the base form a working cavity; Gas is introduced into the working chamber at a third pressure, and the reverse pressure that the engine nozzle plug can withstand is measured.

[0015] Optionally, it also includes: after the positive sealing test, peeling off the core ring, cleaning the static sealing putty on the contact surface between the core ring and the step hole, and reapplying the static sealing putty, then reassembling the core ring in the reverse direction with the base to complete the reverse pressure test, and finally peeling off the core ring, cleaning the static sealing putty on the contact surface between the core ring and the step hole, and reapplying the static sealing putty, and then reassembling the core ring in the positive direction with the base to complete the positive opening test.

[0016] The present invention provides an engine nozzle plug, a manufacturing method, a testing apparatus, and a testing method, which have the following beneficial effects: First, the plug simultaneously possesses reverse pressure bearing, forward opening, and sealing functions. Specifically, a metal pressure-bearing body provides high reverse pressure bearing capacity, an elastic transition layer achieves reliable sealing, and it can be opened controllably under forward pressure, perfectly solving the technical challenges of the "ejection before ignition" condition in special engines. The plug has a simple structure and high reliability, specifically employing a three-layer composite structure of "metal cone + elastic layer," with no moving parts. Functional conversion relies on the inherent properties of the materials, resulting in a compact structure with superior high-temperature resistance and erosion resistance compared to purely flexible plugs. The plug's opening pressure is controllable: by designing the thickness of the transition layer, the elastic modulus, and the cone angle of the pressure-bearing body, the forward opening pressure threshold can be precisely designed, avoiding engine instability caused by opening too early (energy loss) or too late (explosion risk).

[0017] Secondly, this manufacturing method is simple and inexpensive. Specifically, it eliminates the need for complex molding dies; a simple "gluing then cutting" method can produce caps with complex shapes and high fit, significantly reducing manufacturing costs and time. During curing, the use of a standard nozzle's inner profile for support ensures the contour of the transition layer for each product, contributing to consistent opening pressure during mass production.

[0018] Furthermore, this testing device boasts the advantages of multi-functionality and integrated design. Specifically, by installing the mandrel in either the forward or reverse direction, the same device can perform forward sealing / opening tests and reverse pressure tests separately, eliminating the need to manufacture two different sets of tooling. This testing device can realistically simulate working conditions. Specifically, the inner wall of the mandrel is completely consistent with the profile of the actual nozzle expansion section and is made of a composite material (carbon cloth / high silica cloth) similar to that of the actual nozzle, maximally replicating the actual adhesion and stress state between the plug and the nozzle wall, resulting in highly reliable test data. This testing device exhibits excellent sealing performance. Specifically, static sealing putty is used to fill the gap between the mandrel and the base, ensuring that high-pressure gas acts only on the plug and does not leak through the bypass, thus ensuring the accuracy of the test results.

[0019] Furthermore, the testing process is scientific and efficient: utilizing a reusable core ring and static sealing putty, both forward and reverse ultimate load tests are sequentially performed on the same test piece, with clear logic and strong operability. Comprehensive data acquisition: it can simultaneously measure and record multiple key performance parameters such as seal holding time, forward opening pressure, forward opening delay time, and reverse ultimate load pressure, providing complete data support for the design improvement of the plug. Attached Figure Description

[0020] Figure 1 This is a cross-sectional view of the plug for the engine nozzle in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the engine nozzle plug installed in the expansion section of the engine nozzle in an embodiment of the present invention; Figure 3 yes Figure 2 A partially enlarged schematic diagram of the engine nozzle plug installed on the expansion section of the engine nozzle; Figure 4 This is a cross-sectional view of the engine nozzle plug installed in the test apparatus during positive sealing and opening tests in an embodiment of the present invention. Figure 5 This is a cross-sectional view of the base of the engine nozzle plug test device in an embodiment of the present invention; Figure 6 This is a cross-sectional view of the top seat of the engine nozzle plug test device in an embodiment of the present invention; Figure 7 This is a cross-sectional view of the core ring of the engine nozzle plug test device in an embodiment of the present invention; Figure 8 This is a cross-sectional view of the engine nozzle plug installed in the test apparatus during a reverse pressure test, according to an embodiment of the present invention.

[0021] Explanation of reference numerals in the attached figures: 100 - Engine nozzle plug; 110 - Pressure-bearing body; 111 - Bottom; 112 - Support; 120 - Adhesive layer; 130 - Transition layer; 200 - Test apparatus; 210 - Base; 211 - Stepped hole; 2111 - Stepped surface; 220 - Core ring; 221 - Inner layer; 222 - Outer layer; 230 - Top seat; 231 - Air inlet; 232 - Exhaust port; 240 - Working chamber; 300 - Expansion section. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but these embodiments should not be construed as limiting the present invention.

[0023] refer to Figure 1 , Figure 1 This is a cross-sectional view of the plug for the engine nozzle in an embodiment of the present invention. Figure 2 This is a schematic diagram of the structure of the engine nozzle plug installed on the expansion section of the engine nozzle in an embodiment of the present invention. Figure 3 yes Figure 2 A partially enlarged schematic diagram of a plug installed on the expansion section of an engine nozzle. Figure 4 This is a cross-sectional view of the engine nozzle plug installed in the test apparatus during positive sealing and opening tests in an embodiment of the present invention. Figure 5 This is a cross-sectional view of the base of the engine nozzle plug test device in an embodiment of the present invention. Figure 6 This is a cross-sectional view of the top seat of the engine nozzle plug test device in an embodiment of the present invention. Figure 7 This is a cross-sectional view of the core ring of the engine nozzle plug test device in an embodiment of the present invention. Figure 8 This is a cross-sectional view of an engine nozzle plug installed in a test apparatus during a reverse pressure test, according to an embodiment of the present invention. This embodiment provides an engine nozzle plug 100, comprising a pressure-bearing body 110, an adhesive layer 120, and an elastic transition layer 130 for bonding to the expansion section 300 of the engine nozzle. The pressure-bearing body 110 includes a bottom 111 and a support portion 112. The support portion 112 is a rotating body, with its diameter gradually increasing from one end to the other. One end of the support portion 112 is connected to the bottom 111, and the other end is a free end. The adhesive layer 120 is located on the outer surface of the support portion 112. The transition layer 130 is bonded to the support portion 112 via the adhesive layer 120. The pressure-bearing body 110 is made of metal.

[0024] The plug adopts a composite structure of "metal pressure-bearing body + elastic transition layer". When the plug is installed inside the nozzle expansion section 300, the elastic transition layer 130 (such as rubber) undergoes elastic deformation under the installation pre-tightening force, tightly adhering between the inner wall of the expansion section 300 and the support part 112 of the pressure-bearing body 110, forming a reliable static seal to isolate external moisture and dust (sealing function). At the same time, the elastomer is firmly fixed to the metal body through the adhesive layer 120.

[0025] Under reverse pressure conditions (external pressure acting on the bottom 111 of the plug), the pressure tends to push the pressure-bearing body 110 towards the inside of the nozzle. However, because its support part 112 is a conical structure with an outwardly expanding diameter, the inner wall of the expansion section 300 will exert a radially inward restraining force on it. This restraining force balances with the external pressure, making the overall structure of the plug stable and preventing it from falling out. The pressure-bearing body 110 made of metal (especially aluminum alloy) has high specific strength and can withstand huge axial compressive loads without buckling instability, thus achieving a reliable reverse pressure-bearing function.

[0026] Under forward opening conditions (engine ignition, internal high-pressure gas acting on the bottom 111 of the plug), the gas pressure pushes the plug to move outward from the nozzle. At this time, as the conical support 112 moves outward along the axial direction, it radially compresses the elastic transition layer 130. When the gas pressure reaches the designed opening pressure threshold, the elastic deformation of the transition layer 130 reaches its limit, causing it to tear or allowing the pressure-bearing body 110 to slide out from the nozzle, thereby opening the gas passage and enabling the engine to operate normally.

[0027] In this embodiment, the plug simultaneously possesses reverse pressure bearing, forward opening, and sealing functions. Specifically, the metal pressure-bearing body 110 provides high reverse pressure bearing capacity, the elastic transition layer 130 achieves reliable sealing, and it can be opened controllably under forward pressure, perfectly solving the technical challenges of the "ejection before ignition" condition in special engines. The plug has a simple structure and high reliability. Specifically, it adopts a three-layer composite structure of "metal cone + elastic layer," with no moving parts. It relies on the inherent properties of the material to achieve functional conversion, resulting in a compact structure with superior high-temperature resistance and erosion resistance compared to purely flexible plugs. The opening pressure of the plug is controllable: by designing the thickness and elastic modulus of the transition layer 130 and the cone angle of the pressure-bearing body 110, the forward opening pressure threshold can be precisely designed, avoiding engine instability caused by opening too early (energy loss) or too late (explosion risk).

[0028] The bottom 111 protrudes from one end of the support 112 to the other end of the support 112. The protruding bottom 111 structure can more effectively and evenly transfer the reverse pressure load to the support 112, avoid stress concentration at the connection fillet of the bottom 111 and the support 112, and improve the structure's resistance to damage.

[0029] For example, the axial cross-section of the pressure-bearing body 110 is M-shaped.

[0030] The pressure-bearing body 110 is made of aluminum alloy. Aluminum alloy has low density and high specific strength, which minimizes negative mass while meeting pressure requirements, thus improving the engine's thrust-to-weight ratio.

[0031] The transition layer 130 is made of rubber. The use of rubber provides both good elasticity and good sealing properties.

[0032] The pressure-bearing body 110 is made of 7A09 lightweight high-strength aluminum alloy (a metal structural pressure-bearing component that enables reverse pressure bearing of the nozzle plug). The transition layer 130 is made of RP101 natural rubber molded component (the rubber body is destroyed, enabling the nozzle plug to open in the forward direction). The adhesive used for bonding the pressure-bearing body 110 and the transition layer 130, and the transition layer 130 and the expansion section 300, is epoxy adhesive, forming a "sandwich"-like structure. The epoxy adhesive has the characteristics of high strength, good toughness, low temperature resistance, good sealing performance, and rapid curing at room temperature.

[0033] In this embodiment, the plug can withstand a large reverse ejection pressure without deformation (not less than 5MPa). Based on the requirement of a forward opening pressure of 0.7MPa~1.5MPa, the transition layer 130 is designed with a thickness of t=2mm, and the annular area is the same as the plug area. The forward opening pressure is controlled by the destruction of the RP101 rubber layer.

[0034] This embodiment also provides a method for manufacturing the above-mentioned engine nozzle plug 100, including: Fabricate the pressure-bearing body 110; Adhesive is applied to the outer surface of the support portion 112 of the pressure-bearing body 110 and one side of the annular member, and the annular member is bonded to the outer surface of the support portion 112 and cured to form an adhesive layer 120 between the support portion 112 and the annular member. Cut the annular part: cut off the portion of the annular part that extends beyond the support part 112 to ensure that the annular area of ​​the cut annular part is consistent with the bonding area of ​​the support part 112, so as to form a transition layer 130.

[0035] The principle of this manufacturing method lies in "bonding before molding". Since the support portion 112 of the pressure-bearing body 110 is a spatial curved surface, directly molding an elastomer onto it is difficult and results in poor consistency. Therefore, this method first manufactures a precise metal pressure-bearing body 110, and then uses a flat or simply shaped annular component (such as a rubber sheet) to bond it with an adhesive. After the bonding has cured, the excess annular material is precisely trimmed according to the actual contour line of the support portion 112, ultimately forming a perfectly matched and firmly bonded transition layer 130. This method is simple, low-cost, and easy to mass-produce.

[0036] This manufacturing method is simple and inexpensive. Specifically, it eliminates the need for complex molding dies; a simple "gluing then cutting" method can produce caps with complex shapes and high fit, significantly reducing manufacturing costs and time. During curing, the use of a standard nozzle's inner profile for support ensures a 130° profile for each product's transition layer, contributing to consistent opening pressure during mass production.

[0037] Before applying adhesive to the outer surface of the support portion 112 of the pressure-bearing body 110 and one side of the annular part, the outer surface of the support portion 112 is sandblasted and roughened.

[0038] Sandblasting roughening treatment increases the surface roughness of the support 112 at the microscopic level, thereby significantly increasing the wetting area and mechanical locking force of the adhesive, and greatly improving the shear peel resistance of the adhesive layer 120.

[0039] During curing, the adhesive is supported and compressed by the inner surface of the engine nozzle, and the curing time is not less than 24 hours. Using the inner surface of the nozzle for support and compression during curing ensures that the transition layer 130 always fits the theoretically designed surface during the adhesive curing process, guaranteeing the dimensional accuracy of the final plug and its fit with the nozzle. At the same time, the curing time of more than 24 hours ensures that the adhesive reaches its optimal mechanical properties.

[0040] This manufacturing method ensures high bonding quality. Specifically, through sandblasting roughening and contour-guided pressure curing, the bonding strength between the transition layer 130 and the metal body is guaranteed, which can resist the risk of peeling under high and low temperatures and complex stress conditions.

[0041] This embodiment also provides a test apparatus 200 for the engine nozzle plug 100 described above, comprising: a base 210, a core ring 220, and a top seat 230. The top seat 230 has an air inlet 231. The top seat 230 is sealed and mounted on the base 210, and a working cavity 240 is formed between the base 210 and the top seat 230. The working cavity 240 communicates with the air inlet 231. A stepped hole 211 is provided on the end face of the base 210 near the working cavity 240. The ring 220 is installed on the stepped surface 2111 of the stepped hole 211. The core ring 220 is connected to the hole wall of the stepped hole 211 by static sealing putty. The inner wall shape and size of the core ring 220 are the same as the expansion section 300 of the engine nozzle. The inner wall of the core ring 220 is bonded to the transition layer 130 of the engine nozzle plug 100 by adhesive. One end of the inner cavity of the core ring 220 is connected to the working chamber 240, and the other end of the inner cavity of the core ring 220 is connected to the stepped hole 211.

[0042] The core of this experimental device 200 lies in simulating different operating conditions of the nozzle expansion section 300 using a reversible "core ring 220". The working chamber 240 is connected to an external air source via an air inlet 231 to simulate the pressure environment within an engine combustion chamber. The stepped hole 211 on the base 210 is used to position and fix the core ring 220. Static sealing putty is used to fill the gap between the outer wall of the core ring 220 and the inner wall of the stepped hole 211, preventing gas leakage during the test and ensuring that all pressure is applied to the plug. Because the inner wall of the core ring 220 is completely identical to the actual nozzle expansion section 300, the bonding fit between the plug and the core ring 220 accurately reflects its assembly state with the actual nozzle.

[0043] During the forward sealing and opening tests, the core ring 220 is installed with its smaller end closer to the working chamber 240 and its larger end further away from the working chamber 240 (i.e., simulating the direction of gas flow from the converging section to the expanding section 300). At this time, the bottom 111 of the pressure-bearing body 110 of the plug faces the working chamber 240. When pressure is applied to the working chamber 240, the pressure pushes the plug to move outward of the stepped hole 211, simulating the forward opening process of the plug.

[0044] During the reverse pressure test, the core ring 220 is installed in reverse, with its large end close to the working chamber 240 and its small end away from the working chamber 240. At this time, the bottom 111 of the plug faces away from the working chamber 240. When pressure is applied to the working chamber 240, the pressure first acts on the transition layer 130 and the inner wall of the core ring 220, and then is transmitted to the free end of the support part 112 of the pressure-bearing body 110, simulating the reverse pressure process of external aerodynamic force pushing the plug from the outside of the nozzle inward.

[0045] This test apparatus 200 boasts the advantages of multi-functionality and integrated design. Specifically, by installing the core ring 220 in both forward and reverse directions, the same apparatus can perform forward sealing / opening tests and reverse pressure tests separately, eliminating the need to manufacture two different sets of tooling. The test apparatus 200 can realistically simulate working conditions. Specifically, the inner wall of the core ring 220 is completely identical to the profile of the actual nozzle expansion section 300, and it is made of a composite material (carbon cloth / high silica cloth) similar to that of the actual nozzle, maximally replicating the actual adhesion and stress state between the plug and the nozzle wall, resulting in highly reliable test data. The test apparatus 200 exhibits excellent sealing performance. Specifically, static sealing putty is used to fill the gap between the core ring 220 and the base 210, ensuring that high-pressure gas acts only on the plug and does not leak through the bypass, thus ensuring the accuracy of the test results.

[0046] The material of the static sealing putty is D03 rubber-based static sealing putty.

[0047] The core ring 220 includes an inner layer 221 and an outer layer 222. The inner layer 221 is disposed inside the outer layer 222, and the outer layer 222 is engaged with the inner wall of the stepped hole 211 of the base 210. The inner layer 221 is bonded to the transition layer 130 of the engine nozzle plug 100 by an adhesive.

[0048] The core ring 220 is manufactured by impregnation and winding, with the inner layer 221 being a carbon fiber tape layer and the outer layer 222 being a high-silica tape layer. The core ring 220 is made of carbon fiber tape / high-silica tape winding, and its strength and rigidity are similar to those of the actual nozzle expansion section 300 composite material. It is also easy to process into inner surfaces with different tapers. At the same time, the double-layer structure ensures both compatibility with the adhesive (inner layer 221) and adaptability to the seal of the base 210 (outer layer 222).

[0049] The core ring 220 is flush with the end of the stepped hole 211 near the working chamber 240. This eliminates airflow disturbance and pressure loss: the flush alignment of the core ring 220 end face with the stepped hole 211 end face (i.e., the end near the working chamber 240) means that a smooth, continuous plane without abrupt changes is formed between the inlet edge of the core ring 220 inner wall and the wall surface of the stepped hole 211. This design avoids eddies, turbulence, or pressure pulsations caused by structural steps or gaps when high-pressure airflow enters the core ring 220 from the working chamber 240. This ensures that the pressure load acting on the cap is uniform, stable, and highly consistent with theoretical calculations, significantly improving the accuracy and repeatability of reverse pressure and forward opening pressure test results. It also avoids edge stress concentration: the flush mating surfaces eliminate any overhang or excessive extension of the core ring 220 end face. Under high pressure, if the core ring 220 end face protrudes or is recessed, additional bending stress will be generated at the bonding interface or the root of the core ring 220 body. The flush design allows the pressure load to be smoothly transferred from the end face of the core ring 220 to the base 210, avoiding localized stress concentration, protecting the integrity of the adhesive structure between the core ring 220 and the plug, and preventing accidental damage before formal testing. It simplifies installation and positioning, ensuring coaxiality: using the flush end face as an axial positioning reference allows for very intuitive and precise control of the axial installation position of the core ring 220 in the stepped hole 211. This ensures that the position of the plug relative to the working chamber 240 and the air inlet 231 is fixed during each test, eliminating systematic errors introduced by differences in installation position and improving the repeatability and data comparability of the test. Simultaneously, the flush end face helps ensure that the inner axis of the core ring 220 coincides with the overall axis of the base 210 and the top seat 230, ensuring that the force is entirely axial.

[0050] The diameter of the smaller section of the stepped hole 211 gradually increases from the end closer to the working cavity 240 to the end farther away from the working cavity 240.

[0051] In this way, the airflow channel of the nozzle expansion section 300 can be realistically simulated: the expansion section 300 of the engine nozzle itself is a conical channel whose diameter gradually increases from the throat to the outlet, in which the gas accelerates and expands. By designing the corresponding section of the stepped hole 211 of the base 210 to also have a gradually increasing diameter, the flow pattern of gas entering the expansion section 300 from the converging section through the throat in an actual engine can be more realistically simulated after the core ring 220 is installed. This avoids the flow field distortion caused by the stepped hole 211 being a straight hole, making the pressure distribution acting on the plug during the forward opening test closer to the actual ignition condition.

[0052] When the core ring 220 is installed, and the end of the inner wall of the core ring 220 with a smaller diameter is closer to the working chamber 240 than the end with a larger diameter, the end of the smaller diameter segment of the stepped hole 211 smoothly transitions with the inner wall of the core ring 220, and the diameter of the smaller diameter segment of the stepped hole 211 is greater than or equal to the diameter of the end of the core ring 220 furthest from the working chamber 240. The special angle design of the stepped hole 211 ensures smooth airflow and avoids additional pressure loss or disturbance.

[0053] The test device 200 also includes a sealing ring, and a sealing groove is provided on the base 210, with the sealing ring installed in the sealing groove.

[0054] The top seat 230 and the base 210 are connected by bolts. The bolt connection between the top seat 230 and the base 210 makes assembly and disassembly convenient.

[0055] The top seat 230 also includes an exhaust port 232, which is connected to the top seat 230.

[0056] This embodiment also provides a test method for conducting tests using the test apparatus 200 for the engine nozzle plug 100 described above, including: The engine nozzle plug 100 is test-fitted onto the inner wall of the core ring 220 so that the shape of the support part 112 is adapted to the shape of the inner wall of the core ring 220. The bonding surface position is marked on the inner wall of the core ring 220, and then the bonding surface is processed. Apply adhesive to the transition layer of the engine nozzle plug 100, then bond the engine nozzle plug 100 to the inner wall of the core ring 220 and cure it. Perform one of the following tests: forward sealing test, forward opening test, and reverse pressure test: The positive sealing test includes: The core ring 220 is installed on the stepped surface 2111 of the stepped hole 211 using static sealing putty, so that the core ring 220 is installed on the stepped surface 2111 in a first direction, and the smaller diameter end of the inner wall of the core ring 220 is positioned away from the base to simulate the forward installation posture of the engine nozzle expansion section 300. The top seat 230 is mounted on the base 210, and the top seat 230 and the base 210 form a working cavity 240. Gas is introduced into the working chamber 240 at a predetermined time and a first pressure, and the sealing performance of the engine nozzle plug 100 is measured. The forward opening test includes: The core ring 220 is installed on the stepped surface 2111 of the stepped hole 211 using static sealing putty, so that the core ring 220 is installed on the stepped surface 2111 in a first direction, and the smaller diameter end of the inner wall of the core ring 220 is positioned away from the base 210 to simulate the forward installation posture of the engine nozzle expansion section 300. The top seat 230 is mounted on the base 210, and the top seat 230 and the base 210 form a working cavity 240. Gas is introduced into the working chamber 240 at a second pressure, and the pressure when the engine nozzle plug 100 is opened in the forward direction is measured. The reverse bearing test includes: The core ring 220 is installed on the step surface 2111 of the step hole 211 using static sealing putty, so that the core ring 220 is installed on the step surface 2111 in a second direction, and the larger diameter end of the inner wall of the core ring 220 is set away from the base 210 to simulate a reverse pressure posture. The top seat 230 is mounted on the base 210, and the top seat 230 and the base 210 form a working cavity 240; Gas is introduced into the working chamber 240 at a third pressure, and the reverse pressure that the engine nozzle plug 100 can withstand is measured.

[0057] The testing process is scientific and efficient: utilizing the reusable and removable core ring 220 and static sealing putty, both forward and reverse ultimate load assessments, as well as sealing tests, are sequentially performed on the same test piece. The logic is clear and the operation is highly practical. Comprehensive data acquisition: It can simultaneously measure and record multiple key performance parameters, such as seal holding time, forward opening pressure, forward opening delay time, and reverse ultimate load pressure, providing complete data support for the design improvement of the plug.

[0058] The treatment of the bonding surface includes: sanding the marked area with sandpaper and cleaning with ethyl acetate to remove dust. By sanding and cleaning the bonding surface of the core ring 220 with ethyl acetate, oil stains and weak surface layers are effectively removed, ensuring that the bonding strength between the plug and the core ring 220 does not become a weak point during the test, and ensuring that the test is on the performance of the plug itself rather than the bonding performance.

[0059] The test method further includes: after performing the forward sealing test, peeling off the core ring 220, cleaning the static sealing putty on the contact surface between the core ring 220 and the stepped hole 211, and reapplying static sealing putty, then reassembling the core ring 220 in reverse with the base 210 to complete the reverse pressure test; finally, peeling off the core ring 220, cleaning the static sealing putty on the contact surface between the core ring 220 and the stepped hole 211, and reapplying static sealing putty, then reassembling the core ring 220 in the forward direction with the base 210 to complete the forward opening test. By repeatedly using the same core ring 220 and test device 200, it is not necessary to manufacture new test pieces and tooling for each test item, significantly reducing R&D costs and material waste.

[0060] For example, the composite plug first undergoes a forward airtightness test at 0.1 MPa for 12 hours, followed by a reverse pressure test at no less than 5 MPa, and finally a forward opening test at 0.7 MPa to 1.5 MPa. Specifically, the core ring 220 is first assembled with the base 210 in the forward direction to complete the airtightness test. Then, the core ring 220 is peeled off, and after cleaning and reapplying D03 putty to all surfaces, the core ring 220 is assembled with the base 210 in the reverse direction to complete the reverse pressure test. Finally, the core ring 220 is peeled off, and after cleaning and reapplying D03 putty to all surfaces, the core ring 220 is assembled with the base 210 in the forward direction to complete the forward opening test.

[0061] After multiple tests and verifications, the composite nozzle plug passed the forward 0.1MPa, 12h airtightness test and the reverse 5 (0, +0.2)MPa pressure test. The forward opening pressure was 1.14MPa, 1.28MPa, 0.98MPa and 1.06MPa, which meets the forward opening pressure requirements of 0.7MPa~1.5MPa.

[0062] The principle of this test method is to use the same set of equipment to simulate the forward and reverse stress states of the plug in the engine by changing the installation direction of the core ring 220, thereby completing a comprehensive test of the plug's sealing performance, forward opening pressure / time, and reverse pressure resistance. Specifically, the accuracy of the bonding position is ensured through "trial installation-marking-treatment," and the bonding strength is improved through grinding and solvent cleaning. After completing a test under one working condition (such as forward), the core ring 220 can be quickly installed in reverse to conduct a test under another working condition (such as reverse) by cleaning and reapplying static sealing putty. The key to the "repeated" test process is the use of detachable static sealing putty to connect the core ring 220 and the base 210, allowing the core ring 220 to be easily removed from the base 210, cleaned, and reinstalled. This allows the same core ring 220 and the same test piece (plug) to undergo multiple continuous tests under multiple working conditions, greatly saving test costs and time, and accurately obtaining the limit performance data of the plug under both forward and reverse loads.

[0063] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A plug for an engine nozzle, characterized in that, The device includes a pressure-bearing body, an adhesive layer, and an elastic transition layer for bonding with the expansion section of an engine nozzle. The pressure-bearing body includes a bottom and a support portion. The support portion is a rotating body with a gradually increasing diameter from one end to the other. One end of the support portion is connected to the bottom, and the other end of the support portion is a free end. The adhesive layer is located on the outer surface of the support portion, and the transition layer is bonded to the support portion through the adhesive layer. The pressure-bearing body is made of metal.

2. A method for manufacturing an engine nozzle plug as described in claim 1, characterized in that, include: Fabricate the pressure-bearing body; Adhesive is applied to the outer surface of the support portion of the pressure-bearing body and one side of the annular component, and the annular component is bonded to the outer surface of the support portion and cured to form an adhesive layer between the support portion and the annular component. Cut the ring-shaped part: cut off the portion of the ring-shaped part that extends beyond the support part, ensuring that the ring area of ​​the cut ring-shaped part is consistent with the bonding area of ​​the support part, so as to form a transition layer.

3. A test apparatus for an engine nozzle plug as described in claim 1, characterized in that, include: The system comprises a base, a core ring, and a top seat. The top seat has an air inlet and is sealed and mounted on the base. A working chamber is formed between the base and the top seat, and the working chamber communicates with the air inlet. A stepped hole is formed on the end face of the base near the working chamber. The core ring is mounted on the stepped surface of the stepped hole. The core ring and the wall of the stepped hole are connected by static sealing putty. The inner wall shape and size of the core ring are the same as the expansion section of the engine nozzle. The inner wall of the core ring is bonded to the transition layer of the engine nozzle plug with adhesive. One end of the inner cavity of the core ring communicates with the working chamber, and the other end of the inner cavity of the core ring communicates with the stepped hole.

4. The test apparatus as described in claim 3, characterized in that, The core ring includes an inner layer and an outer layer. The inner layer is disposed inside the outer layer, and the outer layer mates with the inner wall of the stepped hole of the base. The transition layer of the inner layer and the plug of the engine nozzle are bonded together with an adhesive.

5. The test apparatus as described in claim 4, characterized in that, The core ring is made by impregnation and winding, the inner layer is a carbon cloth tape layer, and the outer layer is a high-silica cloth tape layer.

6. The test apparatus as described in claim 3, characterized in that, The core ring is flush with the end of the stepped hole near the working cavity.

7. The test apparatus as described in claim 3, characterized in that, The diameter of the smaller section of the stepped hole gradually increases from the end closer to the working cavity to the end farther away from the working cavity.

8. The test apparatus as described in claim 7, characterized in that, When the core ring is installed, and the end of the inner wall of the core ring with a smaller diameter is closer to the working cavity than the end with a larger diameter, the end of the segment with a smaller diameter in the stepped hole smoothly transitions to the inner wall of the core ring, and the diameter of the segment with a smaller diameter in the stepped hole is greater than or equal to the diameter of the end of the core ring away from the working cavity.

9. A test method for conducting tests using the test apparatus for engine nozzle plugs as described in any one of claims 3-8, characterized in that, include: The engine nozzle cap is test-installed on the inner wall of the core ring so that the shape of the support part matches the shape of the inner wall of the core ring. The bonding surface position is marked on the inner wall of the core ring, and then the bonding surface is treated. Apply adhesive to the transition layer of the engine nozzle plug, then bond the engine nozzle plug to the inner wall of the core ring and cure it. Perform one of the following tests: forward sealing test, forward opening test, and reverse pressure test: The positive sealing test includes: The core ring is installed on the stepped surface of the stepped hole using static sealing putty, so that the core ring is installed on the stepped surface in a first direction, and the smaller diameter end of the inner wall of the core ring is positioned away from the base, to simulate the forward installation posture of the engine nozzle expansion section. The top mount is installed on the base, and the top mount and the base form a working cavity. Gas is introduced into the working chamber at a predetermined time and a first pressure, and the sealing performance of the engine nozzle plug is measured. The forward opening test includes: The core ring is installed on the stepped surface of the stepped hole using static sealing putty, so that the core ring is installed on the stepped surface in a first direction, and the smaller diameter end of the inner wall of the core ring is positioned away from the base, to simulate the forward installation posture of the engine nozzle expansion section. The top mount is installed on the base, and the top mount and the base form a working cavity. Gas is introduced into the working chamber at a second pressure, and the pressure at which the plug of the engine nozzle is opened in the forward direction is measured. The reverse bearing test includes: The core ring is installed on the step surface of the stepped hole using static sealing putty, so that the core ring is installed on the step surface in a second direction, and the larger diameter end of the inner wall of the core ring is set away from the base to simulate a reverse pressure posture. The top seat is mounted on the base, and the top seat and the base form a working cavity; Gas is introduced into the working chamber at a third pressure, and the reverse pressure that the engine nozzle plug can withstand is measured.

10. The test method as described in claim 9, characterized in that, Also includes: After the forward sealing test, the core ring is peeled off, the static sealing putty on the contact surface between the core ring and the stepped hole is cleaned, and the static sealing putty is reapplied. Then, the core ring is reassembled with the base in the reverse direction to complete the reverse pressure test. Finally, the core ring is peeled off, the static sealing putty on the contact surface between the core ring and the stepped hole is cleaned, and the static sealing putty is reapplied. Then, the core ring is reassembled with the base in the forward direction to complete the forward opening test.

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