Rocket engine injector insulation structure and reliability examination method thereof

Abstract

The application provides a rocket engine injector heat insulation structure and a reliability checking method thereof, and can solve the problems of high temperature of the upper surface of the injector body and use reliability. The rocket engine injector heat insulation structure comprises an injector body, a heat insulation structure body, a boss and an arc-shaped groove. The outlet section of the injector body is improved from a traditional solid structure to a multi-boss arc-shaped groove structure, the thermal resistance of the high-temperature nozzle to the upstream conduction of the injector is increased, the temperature of the upper surface of the injector body can be reduced, the design difficulty and production cost of the upstream components are reduced, good mechanical resistance and high-temperature structural strength are ensured, the structure weight is reduced without affecting the central flow channel, and the problems of high temperature of the upper surface of the injector body and use reliability are solved.

Description

Technical Field

[0001] This invention belongs to the field of liquid rocket engines, specifically relating to a heat insulation structure for a rocket engine injector and a method for evaluating its reliability. Background Technology

[0002] Rocket engines provide the power for spacecraft orbital maneuvers and attitude adjustments. High-energy propellant flows out through the injector channels, burns inside a slender, thin-walled nozzle, generating high-temperature, high-pressure gas, which is then ejected to produce thrust. During engine operation, the temperature of the high-temperature, high-pressure gas can reach 2700°C, and the temperature of the nozzle outer wall can reach 1200–1500°C. This results in the upstream injector being at a high temperature level, while the temperature control components on the injector typically have a temperature resistance limit of only 350°C, and the safe operating temperature limit of the valve core assemblies installed on the injector is usually no higher than 80°C. The engine is connected to satellites and other spacecraft via docking brackets through the injector body. Due to the weight constraints of the brackets, their temperature resistance is limited.

[0003] Rocket engines operate under drastic temperature and pressure cycles, while also withstanding the immense vibrations and impacts of rocket launches. The rocket engine's nozzle exit section is directly welded to the high-temperature nozzle, bearing both high temperature and high pressure. While structurally serving a connecting function, it must also provide thermal insulation. Furthermore, to match the slender dimensions of the thin-walled nozzle, the nozzle exit section is much smaller than the main nozzle body, resulting in a small contact area at the connection point and making it relatively weak in resisting mechanical forces. Therefore, the nozzle exit section also requires high structural strength.

[0004] In the relevant prior art, a liquid rocket engine injector flange heat insulation structure and liquid rocket engine (patent document CN202311787791.2) provides a liquid rocket engine injector flange heat insulation structure and liquid rocket engine, in which the heat insulation hole is located on the cross rib, and the cross rib is connected to the heat insulation block at the bottom of the injector frame; the root of the cross rib is provided with a semi-circle, and the injector frame increases the thermal resistance to achieve heat insulation by cooperating with the semi-circle and the heat insulation hole. However, since the intersection of the cross rib is prone to forming a stress concentration area, it is prone to cracking under long-term thermal cycling, and the cross rib structure is not strong enough when used for heavier large-size nozzles. This technical solution is only suitable for attitude control engines with small size and light nozzle structure.

[0005] Looking at the current state of technology both domestically and internationally, the connection between rocket engine injectors and nozzles is typically designed as a solid structure to ensure sufficient connection strength and operational reliability. These solid structures have undergone decades of ground testing and on-orbit flight verification, exhibiting outstanding characteristics such as safety, reliability, and high structural strength. However, with the development of high-performance rocket engines, the nozzle temperature has gradually increased, leading to intensified heat conduction upstream to the injector. This results in a significant increase in the temperature of the injector body, upstream propellant control valves, and satellite connection brackets. It has even caused the temperatures of temperature control components, valve core assemblies, and brackets on the injector to exceed safe operating temperature ranges, posing new challenges and risks to the engine's on-orbit operation. Therefore, it is urgent to optimize and improve the existing injector structure and assess its reliability. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a thermal insulation structure for rocket engine injectors and a method for evaluating its reliability.

[0007] A rocket engine injector heat insulation structure according to the present invention includes: an injector body, a heat insulation structure body, a boss, and a flow channel hole;

[0008] The heat insulation structure is located at the outlet section of the injector body; the outer periphery of the heat insulation structure is provided with a plurality of evenly distributed protrusions; the interior of the injector body is provided with flow channel holes.

[0009] Preferably, the rocket engine injector heat insulation structure further includes: an arc-shaped groove and a nozzle; the arc-shaped groove is uniformly arranged between the protrusions; the outlet port of the injector body and the nozzle are welded together as a whole using a high-energy beam.

[0010] Preferably, the bottom of the arc-shaped groove is far from the flow channel hole, the distance from the bottom of the arc-shaped groove to the flow channel hole is not less than 5mm, and the ratio of the depth to the width of the arc-shaped groove is 0.3 to 0.5.

[0011] Preferably, the outer contour of the outlet section of the injector body is cylindrical with a diameter of 30mm to 80mm.

[0012] Preferably, the distance from the end of the heat insulation structure to the outlet end of the injector body is not less than 5 mm.

[0013] Preferably, the width of the boss is 5mm to 10mm; the ratio of the width of the boss to the distance between adjacent bosses is not greater than 0.3.

[0014] Preferably, the number of the bosses and the arc-shaped grooves is the same, both being no less than four.

[0015] Preferably, the body of the injector is made of titanium alloy.

[0016] Preferably, the outer contour of the outlet section of the injector body is cylindrical with a diameter of 70mm; the width of the boss is 6mm; the number of the boss and the number of the arc-shaped groove are the same, both being six; the distance from the bottom of the arc-shaped groove to the flow channel hole is 15mm; the material of the injector body is titanium alloy, grade 7715D or TC4.

[0017] A reliability assessment method for a rocket engine injector heat insulation structure according to the present invention includes:

[0018] Step S1: Design and fabricate the rocket engine injector heat insulation structure provided by the present invention according to the mission requirements;

[0019] Step S2: High-energy beam welding is used to weld the injector body and nozzle, and the thermal effect of high-energy beam welding on the overall structure is assessed. After welding, the structure is not allowed to deform or be damaged.

[0020] Step S3: Conduct a strength test on the rocket engine. The heat insulation structure of the rocket engine injector is tested for a set time under a set multiple of the working pressure. The structure is not allowed to deform or be damaged.

[0021] Step S4: Conduct vibration and impact mechanics tests on the rocket engine in its condition. Perform qualification-level vibration and impact tests on the thermal insulation structure of the rocket engine injector. The structure is not allowed to deform or be damaged.

[0022] Step S5: Conduct a high-altitude simulated hot test on the rocket engine. The heat insulation structure of the rocket engine injector is subjected to high temperature, high pressure and structural tests under real high-altitude simulated working conditions. If the heat insulation structure of the rocket engine injector does not deform or break after the test, the design of the heat insulation structure of the rocket engine injector is considered reasonable.

[0023] If the thermal insulation structure of the rocket engine injector is deformed or damaged in any step, the process must return to step S1 and be redesigned and remanufactured.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. This invention improves the outlet section of the injector from a traditional solid structure to a multi-protrusion arc-shaped groove structure, which increases the thermal resistance of the high-temperature nozzle to the upstream of the injector, and ensures good mechanical resistance and high-temperature structural strength. This can reduce the temperature of the upstream components, thereby reducing the design difficulty and production cost of the upstream components.

[0026] 2. Through structural design, this invention reduces structural weight without affecting the central flow channel; it eliminates stress concentration points and distributes stress evenly, which can reduce thermal deformation stress; the distribution of multiple protrusions forms a ring-shaped symmetrical support, which reduces local load, improves fatigue resistance, has adaptive thermal deformation capability, and balances structural strength and thermal insulation.

[0027] 3. This invention can effectively assess the reliability of the injector's heat insulation structure, ensuring the flight safety of spacecraft;

[0028] 4. The structure of this invention optimizes heat flow distribution by improving the ratio of boss width to spacing, thereby reducing the temperature gradient; and ensures a balance between structural rigidity and thermal insulation performance by setting a reasonable ratio of arc groove depth to width. Attached Figure Description

[0029] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0030] Figure 1 This is a schematic cross-sectional view of the overall heat insulation structure of a rocket engine injector according to the present invention.

[0031] Figure 2 for Figure 1 Enlarged view of the cross-section of BB.

[0032] Figure 3 This is a schematic diagram illustrating the application of the present invention in rocket engine assembly.

[0033] The diagram shows:

[0034] Detailed Implementation

[0035] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0036] like Figures 1 to 3 As shown, an embodiment of the present invention provides a heat insulation structure for a rocket engine injector, including: an injector body 1 and a heat insulation structure body 2, bosses 3, and flow channel holes 5; the heat insulation structure body 2 is disposed at the outlet section of the injector body 1, and a plurality of evenly distributed bosses 3 are disposed on the outer periphery of the heat insulation structure body 2, and the flow channel holes 5 are disposed inside the injector body 1.

[0037] The rocket engine injector heat insulation structure further includes: an arc-shaped groove 4 and a nozzle 6; the arc-shaped groove 4 is evenly arranged between the bosses 3; the bottom of the arc-shaped groove 4 is far away from the flow channel hole 5; the outlet port of the injector body 1 and the nozzle 6 are welded together by high-energy beam welding.

[0038] Furthermore, the outer contour of the outlet section of the injector body 1 is cylindrical with a diameter of 30mm to 80mm. If the diameter is too small, the addition of the heat insulation structure body 2 will result in insufficient structural strength. If the diameter is too large, the injector body 1 itself has a large heat capacity, and the heat insulation effect after adding the heat insulation structure body 2 will not be obvious. The distance from the end of the heat insulation structure body 2 to the outlet end of the injector body 1 is not less than 5mm. If the distance is too small, the heat insulation structure body 2 will be affected by the heat of high-energy beam welding, resulting in deformation. The width of the boss 3 is 5mm to 10mm, which can take into account both good machinability and heat insulation performance. The number of the boss 3 and the arc-shaped groove 4 is the same, both not less than four. The distance from the bottom of the arc-shaped groove 4 to the flow channel hole 5 is not less than 5mm, ensuring that the heat insulation structure body 2 does not affect the flow of propellant in the central flow channel. Furthermore, the ratio of the width of the boss 3 to the distance between adjacent bosses 3 is no greater than 0.3; the ratio of the depth to the width of the arc-shaped groove 4 is 0.3 to 0.5; setting a reasonable ratio of the width to the distance between the bosses 3 optimizes the heat flow distribution and achieves a decrease in the temperature gradient; setting a reasonable ratio of the depth to the width of the arc-shaped groove 4 ensures a balance between structural rigidity and thermal insulation performance.

[0039] The body 1 of the injector is made of titanium alloy, specifically grade 7715D or TC4. Both 7715D and TC4 are high-temperature, high-strength titanium alloy materials with excellent mechanical strength properties, and can be applied to injectors for space attitude and orbit control liquid rocket engines.

[0040] Furthermore, the present invention provides a more specific embodiment in which the outer contour of the outlet section of the injector body 1 is cylindrical with a diameter of 70 mm; the width of the boss 3 is 6 mm; the number of the boss 3 and the number of the arc-shaped groove 4 are the same, both being six; the distance from the bottom of the arc-shaped groove 4 to the flow channel hole 5 is 15 mm; the material of the injector body 1 is titanium alloy, with the grade being 7715D or TC4.

[0041] In a more specific embodiment, the width of the boss 3 is 6mm, the distance between any two bosses 3 is 29.2mm, and the ratio of the width of the boss 3 to the distance between any two bosses 3 is 0.21; the depth of the arc-shaped groove 4 is 10.7mm, the width is 29.2mm, and the depth-to-width ratio is 0.37.

[0042] Furthermore, embodiments of the present invention also provide a reliability assessment method for the rocket engine injector heat insulation structure described in the present invention; including:

[0043] Step S1: Design and fabricate a heat insulation structure for the rocket engine injector described in this invention according to mission requirements;

[0044] Step S2: High-energy beam welding is used to weld the main body 1 of the injector and the nozzle 6. The thermal effect of high-energy beam welding on the overall structure is assessed. After welding, the structure is not allowed to deform or be damaged.

[0045] Step S3: Conduct a strength test on the rocket engine. The thermal insulation structure of the rocket engine injector is tested for 5 minutes or more under twice the working pressure. The structure is not allowed to deform or be damaged.

[0046] Step S4: Conduct vibration and impact mechanics tests on the rocket engine in its condition. Perform qualification-level vibration and impact tests on the thermal insulation structure of the rocket engine injector. The structure is not allowed to deform or be damaged.

[0047] Step S5: Conduct a high-altitude simulated hot test on the rocket engine. The heat insulation structure of the rocket engine injector is subjected to high temperature, high pressure and structural tests under real high-altitude simulated working conditions. If the heat insulation structure of the rocket engine injector does not deform or break after the test, the design of the heat insulation structure of the rocket engine injector is considered reasonable.

[0048] If the thermal insulation structure of the rocket engine injector is deformed or damaged in any step, the process must return to step S1 and be redesigned.

[0049] In summary, this invention provides a thermal insulation structure for a rocket engine injector and its reliability assessment method, which can solve the problems of excessively high surface temperature of the injector body and operational reliability. The outlet section of the injector body 1 is improved from a traditional solid structure to a structure with multiple protrusions 3 and arc-shaped grooves 4, increasing the thermal resistance conducted from the high-temperature nozzle to the upstream of the injector, thus reducing the surface temperature of the injector body and consequently reducing the design difficulty and production cost of upstream components. The special design of the arc-shaped grooves 4 replaces the traditional right-angle intersections, eliminating stress concentration points, and, combined with the overall arc-shaped structure, evenly distributes thermal stress, reducing thermal deformation stress. The distribution of multiple protrusions 3 further forms a ring-shaped symmetrical support, reducing local loads and improving fatigue resistance, enabling the overall structure to possess adaptive thermal deformation capability, balancing structural strength and thermal insulation. Overall, it ensures good mechanical resistance and high-temperature structural strength, reduces structural weight without affecting the central flow channel, and solves the problems of excessively high surface temperature of the injector body and operational reliability.

[0050] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0051] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A heat insulation structure for a rocket engine injector, characterized in that, include: Injector body (1), heat insulation structure body (2), boss (3), flow channel hole (5); The heat insulation structure body (2) is located at the outlet section of the injector body (1); The outer periphery of the heat insulation structure body (2) is provided with a plurality of evenly distributed protrusions (3); The injector body (1) has flow channel holes (5) inside. It also includes: arc-shaped groove (4) and nozzle (6); Arc-shaped grooves (4) are uniformly arranged between the bosses (3); The outlet port of the injector body (1) and the nozzle (6) are welded together as a whole using a high-energy beam.

2. The rocket engine injector heat insulation structure according to claim 1, characterized in that, The bottom of the arc-shaped groove (4) is far away from the flow channel hole (5), the distance from the bottom of the arc-shaped groove (4) to the flow channel hole (5) is not less than 5mm, and the ratio of the depth to the width of the arc-shaped groove (4) is 0.3~0.

5.

3. The rocket engine injector heat insulation structure according to claim 1, characterized in that, The outer contour of the outlet section of the injector body (1) is cylindrical with a diameter of 30mm to 80mm.

4. The rocket engine injector heat insulation structure according to claim 1, characterized in that, The distance from the end of the heat insulation structure body (2) to the outlet end of the injector body (1) is not less than 5 mm.

5. The rocket engine injector heat insulation structure according to claim 1, characterized in that, The width of the boss (3) is 5mm to 10mm; the ratio of the width of the boss (3) to the distance between adjacent bosses (3) is not greater than 0.

3.

6. The rocket engine injector heat insulation structure according to claim 1, characterized in that, The number of the boss (3) and the arc-shaped groove (4) is the same, both being no less than four.

7. The rocket engine injector heat insulation structure according to claim 1, characterized in that, The body of the injector (1) is made of titanium alloy.

8. The rocket engine injector heat insulation structure according to any one of claims 1 to 7, characterized in that, The outer contour of the outlet section of the injector body (1) is cylindrical with a diameter of 70 mm; the width of the boss (3) is 6 mm; the number of the boss (3) and the number of the arc-shaped groove (4) are the same, both being six; the distance from the bottom of the arc-shaped groove (4) to the flow channel hole (5) is 15 mm; the material of the injector body (1) is titanium alloy, grade 7715D or TC4.

9. A reliability assessment method for a rocket engine injector heat insulation structure, characterized in that, include: Step S1: Design and fabricate the rocket engine injector heat insulation structure according to any one of claims 1 to 8 according to mission requirements; Step S2: High-energy beam welding is used to weld the main body (1) of the injector and the nozzle (6) to assess the thermal effect of high-energy beam welding on the overall structure. After welding, the structure is not allowed to deform or be damaged. Step S3: Conduct a strength test on the rocket engine. The heat insulation structure of the rocket engine injector is tested for a set time under a set multiple of the working pressure. The structure is not allowed to deform or be damaged. Step S4: Conduct vibration and impact mechanics tests on the rocket engine in its condition. Perform qualification-level vibration and impact tests on the thermal insulation structure of the rocket engine injector. The structure is not allowed to deform or be damaged. Step S5: Conduct a high-altitude simulated hot test on the rocket engine. The heat insulation structure of the rocket engine injector is subjected to high temperature, high pressure and structural tests under real high-altitude simulated working conditions. If the heat insulation structure of the rocket engine injector does not deform or break after the test, the design of the heat insulation structure of the rocket engine injector is considered reasonable. If the thermal insulation structure of the rocket engine injector is deformed or damaged in any step, the process must return to step S1 and be redesigned and remanufactured.

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