A hydrostatic test tooling for a multi-nozzle structure fiber-wound ignition engine shell and its design method

Abstract

The present invention discloses a hydrostatic test tooling for a multi-nozzle structure fiber-wound ignition engine housing and its design method. A front cover plate for sealing the front joint of the engine housing is provided, and a pressure measuring interface and a pressure boosting interface communicating with the inside of the housing are arranged on the front cover plate. The nozzles of the engine housing are connected through nozzle seals that are hermetically connected to the inner wall of the housing. The present invention is applied to the strength evaluation and verification of a multi-nozzle structure fiber-wound ignition engine housing. By designing the front cover plate, connecting seals, main and auxiliary nozzle locking studs, and sealing gaskets, a test cavity is formed inside the ignition engine housing. By injecting water and pressurizing it to verify the ignition engine housing, the strength and strain conditions of the front joint, rear joint, and fiber winding layer are checked, and the structural reliability of the ignition engine housing and the feasibility of the fiber winding process are evaluated. The present invention can ensure good test sealing effect, accurate test results, and simple structure.

Description

Technical Field

[0001] The invention belongs to the technical field of test tooling, and particularly relates to a water pressure test tooling for a multi-nozzle structure fiber-wound ignition engine shell and a design method thereof. Background Art

[0002] In the field of design and manufacture of solid rocket engines, reducing the engine weight is a continuous pursuit goal under the condition of meeting the structural strength and functional requirements. With the rapid development of fiber composite materials, high-strength, high-modulus, and low-density fiber composite materials are widely used in the design and manufacture of solid rocket engine shells. For a solid rocket engine, the ignition engine is essentially a small solid rocket engine used to ignite the propellant in the solid rocket engine. In the design and manufacture application of large solid rocket engines, there are often multiple nozzles on the ignition engine shell structure, and the shell material is also replaced by fiber composite materials instead of traditional aluminum alloy metal materials.

[0003] For the water pressure test of the ignition engine shell with an aluminum alloy material structure, a water pressure test seal connection interface is usually reserved in the design stage to verify its structural strength through the water pressure test. However, for the multi-nozzle fiber-wound ignition engine shell, there is no publicly available application plan for the water pressure strength test. Summary of the Invention

[0004] Aiming at the problems existing in the background art, the purpose of the present invention is to provide a water pressure test tooling for a multi-nozzle structure fiber-wound ignition engine shell and a design method thereof, which are used to verify the structural strength and material properties of the fiber-wound ignition engine shell.

[0005] To achieve the above purpose, a water pressure test tooling for a multi-nozzle structure fiber-wound ignition engine shell designed by the present invention is characterized in that: a front cover plate that seals the front joint of the engine shell is provided, and a pressure measuring interface and a pressure boosting interface that communicate with the inside of the shell are arranged on the front cover plate; the nozzles of the engine shell are connected through nozzle seals that are sealingly connected to the inner wall of the shell.

[0006] Preferably, a first seal is provided between the front cover plate and the front joint.

[0007] More preferably, the first seal includes a front joint seal groove arranged on the end face of the front joint and an O-ring arranged in the front joint seal groove.

[0008] Preferably, the front cover plate is detachably connected to the front joint through a plurality of connecting bolts; the tightening torque of the connecting bolts is determined by the bolt material strength, a safety factor usually taken as 2, the inner diameter of the O-ring, and the water pressure test pressure.

[0009] Preferably, the nozzle seal includes a nozzle locking stud and a nozzle locking nut, and a nozzle gasket is provided between the nozzle locking stud and the inner wall of the engine housing; the force for sealing the nozzle is applied by the nozzle locking nut.

[0010] More preferably, a nozzle cover plate is provided between the nozzle locking nut and the nozzle end face. In this way, different nozzle cover plates with different shapes and sizes can be used to adapt to different nozzles, which is convenient for standardizing the nozzle locking nut.

[0011] More preferably, before sealing the nozzle, the nozzle gasket is pre-bonded to the position where the nozzle locking stud is adapted to the nozzle seal by a fixture.

[0012] Even more preferably, the fixture includes a positioning ring adapted to the position to be sealed of the nozzle. A groove for accommodating the nozzle gasket is provided at one end of the positioning ring, and a pre-tightening force is applied at the other end through a pressing cover plate; the pressing cover plate applies a pre-tightening force through a pressing nut threadedly connected to the nozzle locking stud.

[0013] A design method for a hydrostatic test tooling of a multi-nozzle structure fiber-wound ignition engine housing designed by the present invention includes the following steps:

[0014] S1. Determine the load conditions borne by the hydrostatic test tooling structure according to the test input conditions;

[0015] S2. Determine the specification of the O-ring according to the size of the sealing groove of the front joint of the ignition engine housing;

[0016] S3. Determine the diameter and thickness of the front cover plate structure according to the structure of the front joint of the ignition engine housing, the test pressure, and the strength of the cover plate material of the safety factor;

[0017] S4. Based on the design theory of the engine connection bolts, determine the length of the connection bolts according to the thickness of the front cover plate and the thread length of the front joint, and determine the bolt tightening torque according to the bolt material strength, safety factor, inner diameter of the O-ring, and hydrostatic test pressure;

[0018] S5. Determine the structure of the nozzle locking stud and the structure of the nozzle locking stud cover plate according to the structure and size of the nozzle of the ignition engine housing;

[0019] S6. Determine the material, diameter, and thickness of the nozzle gasket according to the structure of the nozzle and the nozzle locking stud;

[0020] S7. Determine the bonding and forming die for the sealing gasket according to the structure of the nozzle locking stud and the diameter and thickness of the nozzle gasket;

[0021] S8. Determine the pre-tightening force and tightening torque when the nozzle locking stud is connected to the nozzle locking nut according to the compression amount required for the gasket to be sealed under the test pressure;

[0022] S9. Use finite element software to calculate and analyze the ignition engine, and the stress and strain conditions of the front cover plate and the nozzle locking stud under the test pressure;

[0023] S10. According to the finite element analysis results, confirm whether the structure of the front cover plate, the strength and tightening torque of the connecting bolts, the nozzle locking stud and the tightening torque meet the test strength requirements. Compare the deformation matching of the gasket and the ignition engine housing at the nozzle of the ignition engine housing to see if it meets the sealing requirements.

[0024] The beneficial effects of the present invention are as follows: The water pressure test tooling for the multi-nozzle structure fiber-wound ignition engine housing and its design method of the present invention are applied to the strength evaluation and verification of the multi-nozzle structure fiber-wound ignition engine housing. The water pressure test tooling for the multi-nozzle structure fiber-wound ignition engine housing of the present invention forms a test cavity inside the ignition engine housing by designing the front cover plate and the connecting seal, and the main and auxiliary nozzle locking stud connections and the sealing gasket. By injecting water and pressurizing to verify the ignition engine housing, the strength and strain conditions of the front joint, the rear joint and the fiber winding layer, evaluate the structural reliability of the ignition engine housing and the feasibility of the fiber winding process. This kind of water pressure test tooling can ensure good test sealing effect, accurate test results and simple structure. Description of the Drawings

[0025] Figure 1 is a schematic structural diagram of a multi-nozzle structure fiber-wound ignition engine housing;

[0026] Figure 2 is Figure 1 a side view schematic diagram of

[0027] Figure 3 is a schematic structural diagram of the water pressure test tooling for the ignition engine housing of the present invention;

[0028] Figure 4 is a schematic diagram of the bonding of the main nozzle locking stud and the gasket of the present invention;

[0029] Figure 5 is a schematic diagram of the bonding of the auxiliary nozzle locking stud and the gasket of the present invention.

[0030] Among them: 1. Pressure measuring interface, 2. Pressurizing interface, 3. Connecting bolt, 4. Front cover plate, 5. O-ring, 6. Auxiliary nozzle locking stud, 7. Auxiliary nozzle gasket, 8. Auxiliary nozzle cover plate, 9. Auxiliary nozzle locking nut, 10. Main nozzle locking stud, 11. Main nozzle gasket, 12. Main nozzle cover plate, 13. Main nozzle locking nut. Detailed Embodiments

[0031] The technical solutions (including the preferred technical solutions) of the present invention will be further described in detail below by way of the accompanying drawings and by listing some optional embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts fall within the scope of protection of the present invention.

[0032] As Figure 1 and 2 shown, the shell of a certain ignition engine is 1080 mm long and has a diameter of φ500 mm. It adopts a fiber winding design structure, and its main structure includes: a front joint 21, a rear spherical joint 22, an inner insulation layer 23, an outer insulation layer 24, an ablation-resistant layer 25, and a fiber winding layer 26. At the rear spherical joint 22, there is a main nozzle 27 and four auxiliary nozzles 28, which are used to ignite the propellant in the combustion chamber shell of the engine when the ignition engine burns.

[0033] As Figures 3 to 5 shown, a hydrostatic test tooling for the shell of a multi-nozzle structure fiber-wound ignition engine includes: a pressure measurement interface 1, a pressure injection interface 2, connecting bolts 3, a front cover plate 4, an O-ring 5, auxiliary nozzle locking studs 6, auxiliary nozzle gaskets 7, auxiliary nozzle cover plates 8, auxiliary nozzle lock nuts 9, main nozzle locking studs 10, main nozzle gaskets 11, main nozzle cover plates 12, and main nozzle lock nuts 13.

[0034] Sealing at the front joint 21 is formed by the front cover plate 4, the O-ring 5, and the connecting bolts 3. The O-ring and sealing structure at the front joint 21 are simple and reliable. Ultra-high-strength bolts are used for connection, and a reasonable tightening torque is given under the safety factor to ensure that there is sufficient adhesion between the front cover plate and the front joint when withstanding the water pressure to meet the compression amount requirements for O-ring sealing.

[0035] Sealing at the main nozzle is formed by connecting and pressing with the main nozzle locking stud 10, the main nozzle gasket 11, the main nozzle cover plate 12, and the main nozzle lock nut 13.

[0036] Sealing at the four auxiliary nozzles is formed by the auxiliary nozzle locking stud 6, the auxiliary nozzle gasket 7, the auxiliary nozzle cover plate 8, and the auxiliary nozzle lock nut 9.

[0037] Nozzle cover plates of different shapes and sizes are used to adapt to different nozzles, which is convenient for standardizing the nozzle lock nuts.

[0038] Before sealing the nozzle, the nozzle gasket is pre-bonded to the position where the nozzle locking stud and the nozzle seal are adapted through a fixture. The fixture includes a positioning ring 14 adapted to the position to be sealed of the nozzle. One end of the positioning ring 14 is provided with a groove for accommodating the nozzle gasket, and the other end applies a pre-tightening force through a pressing cover plate 15. The pressing cover plate 15 applies a pre-tightening force through a pressing nut 16 threadedly connected to the nozzle locking stud.

[0039] The design method of the hydrostatic test tooling for the multi-nozzle structure fiber-wound ignition engine shell includes the following steps:

[0040] S1. According to the burst pressure of 25 MPa in the test input conditions, determine the load conditions borne by the designed hydrostatic test tooling structure.

[0041] S2. According to the size of the O-ring seal groove at the front joint of the ignition engine shell, determine the O-ring seal specification of φ190x3.5, and the material is silicone rubber.

[0042] S3. According to the structure of the front joint of the ignition engine shell, the test pressure of 25 MPa, determine the structural dimensions of the front cover plate with a diameter of φ240 mm and a thickness of 30 mm. When the safety factor is taken as 2 times, the material 30CrMnSiA is selected, and the heat treatment is not less than 1200 MPa to ensure the strength and stiffness requirements of the front cover plate structure.

[0043] S4. Based on the design theory of the engine connection bolts, determine the connection bolts as M10x40 hexagon head bolts according to the cover flange thickness of 20 mm and the front joint thread length of 22 mm. According to the bolt material strength of 1440 MPa, the safety factor of 2 times, the O-ring inner diameter of φ190, and the hydrostatic test pressure of 25 MPa, determine the tightening torque of the connection bolts as 35 N﹒m.

[0044] S5. According to the structure and throat dimensions at the main and auxiliary nozzles of the ignition engine shell, determine the structure of the nozzle locking stud. The nozzle locking stud should have a clearance of about 0.2 - 0.3 mm at the mating part with the nozzle to avoid damaging the ablative layer at the nozzle. The structure of the nozzle locking stud backing plate should have a locking clearance not greater than 0.5 mm to avoid deformation at the rear joint during the hydrostatic test, resulting in skew between the locking stud and the backing plate. Since the nozzle locking stud has a small compression surface during the hydrostatic test, the nozzle locking stud is made of 45 steel and its strength after heat treatment is not less than 800 MPa.

[0045] S6. According to the structure of the main nozzle and the nozzle locking stud, determine that the material of the main nozzle gasket is ordinary soft natural rubber, which has good elasticity and good sealing effect after being in contact with the ablative insulation layer under pressure. The outer diameter x inner hole x thickness of the gasket is φ150 mm x φ150 mm x 5 mm.

[0046] S7. Based on the structure of the auxiliary nozzle and the nozzle locking stud, it is determined that the material of the auxiliary nozzle gasket is ordinary soft natural rubber, which has good elasticity and good sealing effect after being compressed in contact with the ablative insulation layer. The outer diameter x inner hole x thickness of the gasket is φ80mm x φ50mm x 5mm;

[0047] S8. According to the structure of the main nozzle locking stud and the nozzle gasket structure, a gasket bonding and forming die is determined. The bonding and forming die is used for the forming of the rubber gasket, and at the same time, the gasket is bonded to the main nozzle locking stud to ensure the sealing performance of the contact surface between the main nozzle locking stud and the gasket;

[0048] S9. According to the structure of the auxiliary nozzle locking stud and the nozzle gasket structure, a gasket bonding and forming die is determined. The bonding and forming die is used for the forming of the rubber gasket, and at the same time, the gasket is bonded to the main nozzle locking stud to ensure the sealing performance of the contact surface between the auxiliary nozzle locking stud and the gasket. Since the auxiliary nozzle is an asymmetric structure, the auxiliary nozzle locking stud, the gasket and the gasket bonding and forming die are all space-shaped special structures. Using the forming die to bond and form the rubber gasket can improve the fitting degree of the rubber gasket with the locking stud and the ablative layer at the auxiliary nozzle, and improve the sealing reliability. When assembling the auxiliary nozzle locking stud with the forming die and the auxiliary nozzle at the rear joint of the ignition engine housing after the ignition engine housing is assembled, anti-misassembly marks should be designed;

[0049] S10. According to the about 35% compression amount required for the sealing of the φ150mm x φ150mm x 5mm natural rubber gasket under the test pressure of 25MPa, it is determined that the tightening torque when the main and auxiliary nozzle locking studs are connected with the M30 locking nut is 150N﹒m;

[0050] S11. According to the about 35% compression amount required for the sealing of the φ80mm x φ50mm x 5mm natural rubber gasket under the test pressure of 25MPa, it is determined that the tightening torque when the auxiliary nozzle locking stud is connected with the M24 locking nut is 120N﹒m;

[0051] S12. With the help of a computer, finite element software such as ANSYS is used to calculate and analyze the ignition engine. The front cover plate and the main and auxiliary nozzle locking studs are loaded on the inner cavity of the ignition engine housing and the pressure-bearing surface of the tooling according to the test pressure of 25MPa, and the overall stress and strain of the theoretical calculation structure are obtained;

[0052] S13. According to the finite element analysis results, confirm whether the structure of the front cover plate, the strength of the connecting bolts and the tightening torque, and whether the main and auxiliary nozzle locking studs and the tightening torque meet the test strength requirements under the safety factor. Compare the deformation matching situation between the gasket and the ignition engine housing at the main and auxiliary nozzles of the ignition engine housing to see if it meets the sealing requirements and whether there is room for further optimization.

[0053] Those skilled in the art can easily understand that the above are only the preferred embodiments of the present invention and do not limit the present invention. Any modifications, combinations, substitutions, improvements, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A hydrostatic test tooling for a multi-nozzle structure fiber-wound ignition engine housing, characterized in that: It includes a front cover plate for sealing the front joint of the engine housing. The front cover plate and the front joint are sealed by an O-ring seal. The front cover plate is detachably connected to the front joint through a plurality of connecting bolts. A pressure measuring interface and a pressure boosting interface communicating with the inside of the housing are provided on the front cover plate. The nozzle of the engine housing is connected through a nozzle seal member sealingly connected to the inner wall of the housing. The nozzle seal member includes a nozzle locking stud and a nozzle locking nut. A nozzle gasket is provided between the nozzle locking stud and the inner wall of the engine housing. The force for sealing the nozzle is applied through the nozzle locking nut.

2. The hydrostatic test tooling for a multi-nozzle structure fiber-wound ignition engine housing according to claim 1, characterized in that: A front joint seal groove is provided on the end face of the front joint. The O-ring seal is located in the front joint seal groove.

3. The hydrostatic test tooling for a multi-nozzle structure fiber-wound ignition engine housing according to claim 1, characterized in that: The tightening torque of the connecting bolt is determined by the bolt material strength, a safety factor usually taken as 2, the inner diameter of the O-ring seal, and the hydrostatic test pressure.

4. The hydrostatic test tooling for a multi-nozzle structure fiber-wound ignition engine housing according to claim 1, characterized in that: A nozzle cover plate is provided between the nozzle locking nut and the nozzle end face.

5. The hydrostatic test tooling for a multi-nozzle structure fiber-wound ignition engine housing according to claim 1 or 4, characterized in that: Before sealing the nozzle, the nozzle gasket is pre-bonded to the position where the nozzle locking stud is adapted to the nozzle seal through a fixture.

6. The hydrostatic test tooling for a multi-nozzle structure fiber-wound ignition engine housing according to claim 5, characterized in that: The fixture includes a positioning ring adapted to the position to be sealed of the nozzle. A groove for accommodating the nozzle gasket is provided at one end of the positioning ring, and a pre-tightening force is applied through a pressing cover plate at the other end. The pressing cover plate applies a pre-tightening force through a pressing nut threadedly connected to the nozzle locking stud.

7. A design method for the hydrostatic test tooling for a multi-nozzle structure fiber-wound ignition engine housing according to any one of claims 1 to 6, comprising the following steps: S1. Determine the load conditions borne by the structure of the hydrostatic test tooling according to the test input conditions. S2. Determine the O-ring seal specification according to the size of the front joint seal groove of the ignition engine housing. S3. Determine the diameter and thickness of the front cover plate structure according to the structure of the front joint of the ignition engine housing, the test pressure, and the cover plate material strength of the safety factor. S4. Based on the engine connecting bolt design theory, determine the length of the connecting bolt according to the thickness of the front cover plate and the thread length of the front joint. Determine the bolt tightening torque according to the bolt material strength, safety factor, inner diameter of the O-ring seal, and hydrostatic test pressure. S5. Determine the structure of the nozzle locking stud and the structure of the nozzle locking stud cover plate according to the structure and size of the nozzle of the ignition engine housing. S6. Determine the material, diameter, and thickness of the nozzle gasket according to the structure of the nozzle and the nozzle locking stud. S7. Determine the sealing washer bonding and forming die according to the structure of the nozzle locking stud and the diameter and thickness of the nozzle gasket. S8. Determine the pre-tightening force and tightening torque when the nozzle locking stud is connected to the nozzle locking nut according to the compression amount required for the gasket to seal under the test pressure. S9. Use finite element software to calculate and analyze the stress and strain conditions of the ignition engine, the front cover plate, and the nozzle locking stud under the test pressure. S10. According to the finite element analysis results, confirm whether the front cover plate structure, the strength and tightening torque of the connecting bolts, the nozzle locking stud and the tightening torque meet the test strength requirements. Compare whether the deformation matching of the gasket and the ignition engine housing at the nozzle of the ignition engine meets the sealing requirements.

Images