A 3D printed injector shell blank for regenerative cooling of low-thrust rockets

Abstract

The present invention provides a 3D printed injector shell blank for regenerative cooling of a small thrust rocket. The blank adopts 3D printing technology as a whole, including a first cylinder, a first ring, a second ring and a third ring. The first ring is located at the outer circumference of the first cylinder, the second ring is located at the outer circumference of the first ring, and the upper end face of the second ring is lower than the upper end face of the first ring. The third ring is located at the outer circumference of the second ring, and the upper end face of the third ring is lower than the upper end face of the second ring. The outer side wall of the third ring is externally connected to an external flow channel, a vertical first flow channel is processed on the second ring, and a vertical third flow channel is processed on the external flow channel. The first flow channel and the third flow channel are connected at both ends of the second flow channel, and the three flow channels together constitute the cooling flow channel of the injector shell. The present invention can effectively reduce the manufacturing cost of rocket injectors, reduce the difficulty of production process, ensure the stability of mass production, optimize the cooling flow channel structure to make the structure more compact and reduce the weight of parts.

Description

Technical Field

[0001] The invention belongs to the technical field of rocket engine injector parts manufacturing, and in particular relates to a 3D printed injector shell blank for regenerative cooling of a small thrust rocket. Background Art

[0002] The injector is one of the parts of the thrust chamber of a rocket engine. It can fully atomize the propellant and spray it into the combustion chamber for combustion. Its design reliability has a significant impact on the combustion efficiency of the thrust chamber. Nowadays, 3D printing technology has been invested in the field of aerospace manufacturing on a large scale. 3D printing can effectively improve production efficiency, shorten the manufacturing cycle, simplify the production process, and reduce costs and material waste. Since 3D printing technology can accurately control the external dimensions, roughness and other parameters of parts, it can ensure the stability of part quality and improve product reliability. However, the tolerance accuracy of rocket injectors is high, and the errors caused by the production process have a huge impact on the performance of the thrust chamber. The tolerance accuracy of 3D printing cannot meet the processing of some precise dimensions of small thrust attitude control rocket engines, and fine processing is required on 3D printed blanks to ensure accuracy.

[0003] Regenerative cooling is an active thermal protection method that allows the propellant to flow through a cooling device before entering the combustion chamber to participate in combustion. Currently, the most common method is to machine a cooling jacket between the inner and outer walls of the engine to remove the heat, but this structure results in the engine being a multi-layer thin-walled structure, which is difficult to process. Currently, there are also pipeline cooling channels that connect the combustion chamber and the solenoid valve, but the channel design does not pass through the injector housing, which results in a complex channel structure and an overall structure that is not compact enough, making it difficult to meet the design requirements of a precision and miniaturized regenerative cooling low-thrust rocket engine. Summary of the invention

[0004] The technical problem solved by the present invention is to provide a 3D printed injector shell blank for regenerative cooling of small thrust rockets, taking into account the advantages of 3D printing and traditional machining, and adding a cooling channel design to the injector shell to solve the above-mentioned problem.

[0005] The technical solution adopted by the present invention is: a 3D printed injector shell blank for regenerative cooling of a small thrust rocket, the blank as a whole is a cylindrical structure with a stepped annular surface, including a first cylinder, a first ring, a second ring and a third ring, an axially penetrating propellant through hole is processed on the first cylinder, the first ring is located on the outer circumference of the first cylinder, the second ring is located on the outer circumference of the first ring, and the upper end face of the second ring is lower than the upper end face of the first ring, the third ring is located on the outer circumference of the second ring, and the upper end face of the third ring is lower than the upper end face of the second ring, and an external flow control valve is connected to the outer side wall of the third ring The external flow channel is a cylinder whose upper part is embedded with the third ring. A vertical first flow channel is processed on the second ring. The inlet of the first flow channel is located on the upper end surface of the second ring. A vertical third flow channel is processed on the external flow channel. The outlet of the third flow channel is located on the bottom surface of the external flow channel. The second flow channel is arranged inside the blank of the injector housing. The inlet end of the second flow channel is connected to the outlet of the first flow channel, and the outlet end of the second flow channel is connected to the inlet of the third flow channel. The first flow channel, the second flow channel and the third flow channel together constitute the cooling flow channel of the injector housing. The blank is integrally formed by 3D printing technology, and the overall tolerance accuracy is 0.1mm.

[0006] Preferably, the first flow channel is a cavity with a long arc-shaped cross-section arranged close to the outer wall of the first circular ring, the width of the first flow channel is less than half the width of the second circular ring, and the second circular ring outside the first flow channel is used to connect the second circular ring with the end face of the combustion chamber to prevent insufficient welding allowance or deformation of the first flow channel during welding, or interference of the nut during flange connection.

[0007] Preferably, injection holes are processed on the first ring.

[0008] Preferably, the inlet of the first flow channel is connected to the outlet of the combustion chamber regeneration cooling flow channel, and the outlet of the third flow channel is connected to the inlet of the valve regeneration cooling flow channel, so as to realize the cooling flow channel connection between the upstream and downstream structures of the injector.

[0009] Preferably, the shortest distance between the second flow channel side wall and the outer wall of the blank is H, and the shortest distance between the second flow channel side wall and the inner wall of the blank is h. The shortest distance H between the second flow channel side wall and the outer wall of the blank and the shortest distance h between the second flow channel side wall and the inner wall of the blank are both greater than or equal to 2 mm to ensure that the shell wall thickness meets the strength requirements.

[0010] Preferably, the second flow channel is inclined, and the cross-sectional area of ​​the second flow channel is smaller than the cross-sectional area of ​​the third flow channel. The outlet end of the second flow channel is beveled to one side of the inlet end of the third flow channel, and the other side of the inlet end of the third flow channel still retains a right-angle end face to facilitate tool entry during machining.

[0011] The beneficial effects of the present invention are as follows: the present invention can effectively reduce the manufacturing cost of small thrust rocket injectors, reduce the difficulty of the production process, ensure the stability of mass production, and reduce the defective rate. The present invention optimizes the cooling channel structure to make the structure more compact and reduce the weight of parts, which is convenient for subsequent machining operations, improves operating efficiency while ensuring machining accuracy, and realizes mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Schematic diagram of the injector housing blank structure.

[0013] Figure 2 A top view of the injector housing blank.

[0014] Figure 3 This is a bottom view of the injector housing blank.

[0015] Figure 4 Schematic diagram of the cooling channel structure.

[0016] Figure numerals: 1 - first cylinder, 2 - propellant through hole, 3 - first circular ring, 4 - second circular ring, 5 - third circular ring, 6 - external flow channel, 7 - first flow channel, 8 - second flow channel, 9 - third flow channel. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. The description of directions such as up, down, inside, outside and Figure 4 The view direction is consistent.

[0018] like Figures 1 to 4As shown, a 3D printed injector shell blank for regenerative cooling of a small thrust rocket is designed with a reserve for later fine machining. The injector injection holes, regenerative cooling channels and other details are machined to ensure that the manufacturing acceptance meets the design requirements. The blank is a cylindrical structure with a stepped annular surface, including a first cylinder 1, a first ring 3, a second ring 4 and a third ring 5. The first cylinder 1 is a cylinder, and a vertically penetrating propellant through hole 2 is machined on the first cylinder 1. The first ring 3 is a torus, and the first ring 3 is located on the outer circumference of the first cylinder 1. The second ring 4 is a torus, and the second ring 4 is located on the outer circumference of the first ring 3, and the upper end face of the second ring 4 is lower than the upper end face of the first ring 3. The third ring 5 is a torus, and the third ring 5 is located on the outer circumference of the second ring 4, and the third ring 5 is a torus. The upper end face of the ring 5 is lower than the upper end face of the second ring 4. In order to prevent the circumferential dimensions of the injector and the valve from being inconsistent, and to ensure that factors such as the temperature of the regenerated cooling fluid do not affect the inside of the injector, an external flow channel 6 is connected to the outer wall of the third ring 5. The external flow channel 6 is a cylinder whose upper part is embedded with the third ring 5, and its upper end face is flush with the upper end face of the third ring 5. The lower end faces of the first cylinder 1, the first ring 3, the second ring 4 and the third ring 5 are located in the same plane, and the lower end face of the external flow channel 6 protrudes from the plane where the lower end face of the third ring 5 is located. A vertical first channel 7 is processed on the second ring 4, and the inlet of the first channel 7 is located at the upper end face of the second ring 4. A vertical third channel 9 is processed on the external channel 6, and the outlet of the third channel 9 is located at the lower end face of the external channel 6. The second channel 8 is arranged inside the shell blank, and the inlet end of the second channel 8 is connected to the outlet of the first channel 7, and the outlet end of the second channel 8 is connected to the inlet of the third channel 9. The first channel 7, the second channel 8 and the third channel 9 together constitute the cooling channel of the injector shell. The blank is integrally formed using 3D printing technology, and the overall tolerance accuracy is 0.1mm. Since the center of the injector is vertical, the first channel 7 and the third channel 9 are designed as vertical channels to better fit the outlet end face of the combustion chamber regeneration cooling channel and the inlet end face of the valve regeneration cooling channel. Moreover, designing the third channel 9 as a vertical cylindrical channel can stabilize the flow direction and the flow in the cooling channel.

[0019] The inlet of the first flow channel 7 is connected to the outlet of the combustion chamber regeneration cooling flow channel, and the outlet of the third flow channel 9 is connected to the inlet of the valve regeneration cooling flow channel, so as to realize the cooling flow channel connection between the upstream and downstream structures of the injector. The outlet of the third flow channel 9 is connected to the regeneration cooling flow channel of the solenoid valve. Considering the sealing design requirements, the third flow channel needs to be machined to improve the accuracy.

[0020] like Figure 2As shown, based on the background that the second circular ring 4 has a small area, in order to increase the flow area of ​​the first flow channel 7 as much as possible and avoid too large changes in the flow area of ​​each flow channel, the first flow channel 7 is designed as a cavity with a long arc cross section. The change in flow area will cause the flow resistance to change, affecting the supply pressure of the upstream tank. Moreover, the first flow channel 7 is a cavity with a long arc cross section that is arranged close to the outer wall of the first circular ring 3. The width of the first flow channel 7 is less than half the width of the second circular ring 4. The plane structure of the second circular ring 4 outside the first flow channel 7 is used to connect the second circular ring 4 with the end face of the combustion chamber, so as to prevent insufficient welding allowance or deformation of the first flow channel 7 during welding or too deep welding penetration, resulting in welding residues being retained in the first flow channel 7, or interference of the nut during flange connection.

[0021] During subsequent machining, small injection holes are machined on the first ring 3 .

[0022] like Figure 4 As shown, the shortest distance between the side wall of the second flow channel 8 and the outer wall of the blank is H, and the shortest distance between the side wall of the second flow channel 8 and the inner wall of the blank is h. The shortest distance H between the side wall of the second flow channel 8 and the outer wall of the blank and the shortest distance h between the side wall of the second flow channel 8 and the inner wall of the blank should be greater than or equal to 2mm to ensure that the wall thickness of the injector shell meets the strength requirements. The second flow channel 8 is inclined, and the cross-sectional area of ​​the second flow channel 8 is smaller than the cross-sectional area of ​​the third flow channel 9. The outlet end of the second flow channel 8 is obliquely connected to one side of the inlet end of the third flow channel 9, and the other side of the inlet end of the third flow channel 9 still retains a right-angle end face for easy entry of the tool during machining.

[0023] The above are specific embodiments of the present invention and the technical principles used. Any modifications and equivalent changes based on the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A 3D printed injector housing blank for regenerative cooling of a low-thrust rocket, characterized in that: The blank as a whole is a cylindrical structure with a stepped annular surface, including a first cylinder, a first ring, a second ring and a third ring. An axially penetrating propellant through hole is processed on the first cylinder. The first ring is located on the outer circumference of the first cylinder, the second ring is located on the outer circumference of the first ring, and the upper end face of the second ring is lower than the upper end face of the first ring. The third ring is located on the outer circumference of the second ring, and the upper end face of the third ring is lower than the upper end face of the second ring. An external flow channel is connected to the outer side wall of the third ring. The external flow channel is a cylinder whose upper part is embedded with the third ring. A vertical first flow channel is processed on the second ring, and the inlet of the first flow channel is located on the upper end face of the second ring. A vertical third flow channel is processed on the external flow channel, and the outlet of the third flow channel is located on the outer side wall of the third ring. The cooling channel of the injector housing is formed on the lower end surface of the flow channel, the second flow channel is arranged inside the blank of the injector housing, the inlet end of the second flow channel is connected to the outlet of the first flow channel, and the outlet end of the second flow channel is connected to the inlet of the third flow channel. The first flow channel, the second flow channel and the third flow channel together constitute the cooling channel of the injector housing, the inlet of the first flow channel is connected to the outlet of the combustion chamber regeneration cooling channel, and the outlet of the third flow channel is connected to the inlet of the valve regeneration cooling channel. The second flow channel is inclined, and the cross-sectional area of ​​the second flow channel is smaller than the cross-sectional area of ​​the third flow channel. The outlet end of the second flow channel is beveled to one side of the inlet end of the third flow channel, and the other side of the inlet end of the third flow channel still retains a right-angle end face for easy entry of the tool during machining. The blank is integrally formed using 3D printing technology, and the overall tolerance accuracy is 0.1mm.

2. A 3D printed injector housing blank for regenerative cooling of a low-thrust rocket according to claim 1, characterized in that: The first flow channel is a cavity with a long arc-shaped cross section and is arranged closely to the outer side wall of the first circular ring. The width of the first flow channel is less than half of the width of the second circular ring.

3. The 3D printed injector housing blank for regenerative cooling of a low-thrust rocket according to claim 1, characterized in that: The first ring is processed with injection holes.

4. The 3D printed injector housing blank for regenerative cooling of a low-thrust rocket according to claim 1, characterized in that: The shortest distance between the second flow channel side wall and the outer wall of the blank is H, and the shortest distance between the second flow channel side wall and the inner wall of the blank is h. The shortest distance H between the second flow channel side wall and the outer wall of the blank and the shortest distance h between the second flow channel side wall and the inner wall of the blank are both greater than or equal to 2 mm.

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