Extrusion type rocket Laval nozzle based on mature industrial manufacturing system and preparation method

Abstract

The invention discloses an extrusion type rocket Laval nozzle based on a mature industrial manufacturing system and a preparation method. The extrusion type rocket Laval nozzle comprises an outer Laval nozzle body, a combustion chamber, a diffusion nozzle body, an upper spiral flow guide belt and a lower spiral flow guide belt. The preparation method of the structure is matched with a mature industrial system, all equipment and processes are mature technologies in the fields of nuclear power equipment, civil boilers, pressure vessels and the like, aerospace customization equipment is not needed, the production threshold is lowered, and the manufacturing cost is reduced to the minimum; according to the preparation method, after all girth welding is completed, refined weld joint grains are forged and pressed in a heated state through forging and pressing treatment, the strength and the sealing performance are improved, and the problems that a traditional spray pipe weld joint is prone to cracking and leakage are solved; the combustion chamber and the diffusion spray pipe are in cold fitting interference fit, stress-free sleeving is achieved through cooling shrinkage, natural attachment is achieved after temperature returning, and a stable spiral cooling flow channel is formed in the pipe wall.

Description

Technical Field

[0001] This invention specifically relates to a squeeze-type rocket Laval nozzle and its preparation method. Background Technology

[0002] Currently, launch vehicles include two main types: solid fuel and liquid fuel. Solid fuel rockets have the disadvantages of high cost and low payload capacity, while liquid fuel rockets mostly require complex turbopumps to pressurize the fuel, resulting in disadvantages such as complex structure, low reliability, and high cost.

[0003] Extrusion rockets eliminate the need for expensive turbopumps, offering advantages such as low cost, simple structure, and reliability. The Laval nozzle is the core thrust component of an extrusion rocket engine, requiring a unique curved surface configuration in its contraction, throat, and expansion sections to accelerate the propellant gas from subsonic to supersonic speeds. Its operating environment involves high-temperature gas scouring and circulating cooling medium pressure, placing stringent requirements on structural strength, sealing performance, and high-temperature stability. Current Laval nozzles for extrusion rocket engines still suffer from numerous insurmountable defects in traditional nozzle structures and mainstream manufacturing processes.

[0004] Firstly, while current mainstream 3D printing processes can achieve integrated manufacturing of complex structures, they still have significant technical limitations: industrial-grade metal 3D printers require investments of millions to tens of millions of yuan, and the cost of special metal powder materials is 3-5 times that of traditional materials. Furthermore, the printing process is prone to internal defects such as micropores, incomplete fusion, and delamination, resulting in poor batch performance consistency of nozzles. At the same time, 3D printing has a long molding cycle; even printing small and medium-sized nozzles takes several days or even weeks, making it difficult to meet the large-scale, rapid iteration production needs of commercial aerospace. Moreover, subsequent complex post-processing processes such as hot isostatic pressing are required to compensate for material performance shortcomings, further increasing manufacturing costs.

[0005] Secondly, the spiral cooling channel processing technology has inherent defects: traditional machining methods form the channel by slotting the inner tube wall, which is difficult to process and difficult to control the precision, and is prone to the risk of cooling medium leakage; while 3D printing can form an integrated channel, the inner wall of the channel has a high roughness, which can easily generate flow resistance, and there is a risk of channel blockage during the printing process. At the same time, the interlayer bonding strength of metal 3D printed parts is usually lower than the intralayer strength, and the channel is prone to cracking and failure under high temperature and high pressure cycling conditions.

[0006] Currently, the nuclear power equipment, boiler, pressure vessel, and shipbuilding industries have established a complete design system for double-layer jacketed, spiral flow-guiding, and nuclear-grade sealing structures. These structures possess core advantages such as high strength, high sealing performance, and fatigue resistance, and can be mass-produced using conventional industrial equipment. This invention provides a rocket Laval nozzle based on a mature industrial manufacturing system. By adapting its structural design to mature processes in nuclear power equipment, civilian boilers, and pressure vessels, it achieves low-cost molding and highly reliable operation of a double-walled spiral cooling structure, particularly suitable for the needs of extrusion-type liquid rocket engines. Summary of the Invention

[0007] To overcome the shortcomings mentioned above, this invention aims to solve the problems of incompatibility between existing rocket Laval nozzle structure design and industrial manufacturing processes, high manufacturing costs, and insufficient sealing and reliability.

[0008] This invention proposes a squeeze-type rocket Laval nozzle based on a mature industrial manufacturing system, which includes: an outer Laval nozzle, a combustion chamber, a diffuser nozzle, an upper spiral guide band, and a lower spiral guide band; The bottom of the combustion chamber has a converging section, and the top of the diffuser nozzle has a neck section. The converging section and the neck section are fixed together by circumferential welding. The outer Laval tube is coaxially sleeved on the outside of the connection structure between the combustion chamber and the diffuser nozzle; the outer Laval tube, combustion chamber, and diffuser nozzle are all made of stainless steel. The upper spiral guide strip and the lower spiral guide strip are made of flat steel. The upper spiral guide strip is wound around and welded to the outer wall of the combustion chamber according to a preset pitch, and the lower spiral guide strip is wound around and welded to the outer wall of the diffuser nozzle according to a preset pitch. The upper spiral guide strip and the lower spiral guide strip do not contact each other. The upper spiral guide band and the lower spiral guide band form a spiral cooling channel between the outer Laval tube and the combustion chamber and the diffuser nozzle; Preferably, the combustion chamber has an annular upper seal on its top outer side, and the outer edge of the upper seal is fixed to the top of the outer Laval tube by circumferential welding. The diffuser nozzle has an annular lower seal on its bottom outer side, and the outer edge of the lower seal is fixed to the bottom of the outer Laval tube by circumferential welding. Preferably, the outer outer wall at the upper end and the outer outer wall at the lower end of the outer Laval tube are respectively provided with a fuel outlet pipe and a fuel inlet pipe. The diameter of the fuel outlet pipe is larger than the band size of the upper spiral guide band, and the diameter of the fuel inlet pipe is larger than the band size of the lower spiral guide band.

[0009] A method for preparing an extruded rocket Laval nozzle based on a mature industrial manufacturing system, applicable to any of the above-mentioned extruded rocket Laval nozzles based on a mature industrial manufacturing system, comprising: split molding preparation, assembly of the whole tube structure, and sealing of the whole tube structure. Preferably, the split molding preparation includes: Select stainless steel plates of a preset size and use a three-roll plate rolling machine to roll the combustion chamber, convergent section and diffuser nozzle respectively. The three parts are then machine-welded around the circumferential seam and subjected to post-weld forging treatment. The combustion chamber and the convergent section are circumferentially welded and then forged after welding to form an integral piece. Cut nuclear-grade stainless steel flat bars to the design dimensions, and prepare upper and lower spiral guide strips by winding them with a spiral coiling machine. The upper spiral guide strip is wound and welded to the outer wall of the combustion chamber and the converging section, and the lower spiral guide strip is wound and welded to the outer wall of the diffuser nozzle. The annular upper and lower seals are manufactured using a stamping process, and the upper seal is welded to the top of the combustion chamber, while the lower seal is welded to the bottom of the diffuser nozzle. Preferably, the forging process is as follows: After all circumferential welds are completed, forging should be carried out immediately while the weld is still hot using a forging press, wherein the arc-shaped structure of the forging press head is adapted to the weld contour. Preferably, the integrated pipe structure kit includes: The combustion chamber and diffuser nozzle are cooled to below -50°C, causing their outer diameters to shrink. Remove the diffuser nozzle and place it vertically. Then, coaxially fit the outer Laval tube onto the outside of the diffuser nozzle from top to bottom. Remove the combustion chamber and insert it from top to bottom into the upper end of the outer Laval nozzle, so that the converging section abuts against the neck section of the diffuser nozzle; After the combustion chamber and diffuser nozzle naturally cool down, their volumes expand, causing the upper and lower spiral guide bands to adhere to the inner wall of the outer Laval tube. Preferably, the integral pipe structure sealing includes the following steps: A 30° nuclear power standard V-groove is opened at the junction of the converging section and the neck section, and a composite welding process of argon arc welding for the root pass and plasma welding for the cover pass is used for circumferential welding. Adjust the coaxiality between the outer edge of the upper seal and the top of the outer Laval tube, and the coaxiality between the outer edge of the lower seal and the bottom of the outer Laval tube, and perform sealing welding using an automatic circumferential welder; The fuel outlet pipe and fuel inlet pipe are respectively inserted into the pre-set mounting holes of the outer Laval pipe and then welded.

[0010] Compared with the prior art, the advantages of the present invention are: The preparation method of the structure of this invention is compatible with mature industrial systems. All equipment and processes rely on mature technologies in fields such as nuclear power equipment, civil boilers, pressure vessels, and shipbuilding. No aerospace-customized equipment is required, which lowers the production threshold and minimizes manufacturing costs.

[0011] In the preparation method of the present invention, after all circumferential welds are completed, they are subjected to forging treatment to refine the weld grains under heat forging, thereby improving strength and sealing performance and avoiding the problems of easy cracking and leakage of traditional nozzle welds.

[0012] The cold-fitting interference fit of the combustion chamber and diffuser nozzle of this invention achieves stress-free assembly through cooling contraction, and naturally fits together after warming up, thus forming a stable spiral cooling flow channel inside the pipe wall of this invention.

[0013] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is an exploded view of the structure of the present invention.

[0016] Figure 2 This is a cross-sectional view of the structure of the present invention. Detailed Implementation

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] In the description of this invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "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 invention 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 invention.

[0019] Furthermore, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components; they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0020] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0021] Please see Figures 1-2 In this embodiment of the invention, a squeeze-type rocket Laval nozzle based on a mature industrial manufacturing system includes: an outer Laval nozzle 1, a combustion chamber 3, a diffuser nozzle 2, an upper spiral guide band 5, and a lower spiral guide band 6.

[0022] The combustion chamber 3 has a converging section 4 at its bottom and a neck section at its top, with the converging section 4 and the neck section fixed together by circumferential welding. An outer Laval tube 1 is coaxially sleeved on the outside of the connection structure between the combustion chamber 3 and the diffuser nozzle 2. The outer Laval tube 1, combustion chamber 3, and diffuser nozzle 2 are all made of stainless steel. This structure can be manufactured and mass-produced based on a mature industrial manufacturing system, thereby reducing manufacturing costs.

[0023] The upper spiral guide band 5 and the lower spiral guide band 6 are made of flat steel. The upper spiral guide band 5 is wound around the outer wall of the combustion chamber 3 according to a preset pitch and welded to the outer wall of the diffuser nozzle 2 according to a preset pitch. The upper spiral guide band 5 and the lower spiral guide band 6 do not contact each other. Therefore, when installing the combustion chamber 3 and the diffuser nozzle 2, no precise calibration is required. The spiral cooling channel can be unobstructed by any contact between the converging section 4 of the combustion chamber 3 and the neck section of the diffuser nozzle 2. This avoids the interruption of the spiral cooling channel due to installation misalignment, improves the fault tolerance rate of installation docking, and thus improves installation efficiency.

[0024] The upper spiral guide band 5 and the lower spiral guide band 6 form a spiral cooling channel between the outer Laval tube 1, the combustion chamber 3, and the diffuser nozzle 2.

[0025] An annular upper seal 7 is provided on the outer side of the top of the combustion chamber 3. The outer edge of the upper seal 7 is fixed to the top of the outer Laval tube 1 by circumferential welding. An annular lower seal 8 is provided on the outer side of the bottom of the diffuser nozzle 2. The outer edge of the lower seal 8 is fixed to the bottom of the outer Laval tube 1 by circumferential welding.

[0026] The outer outer wall of the outer Laval pipe 1 is provided with a fuel outlet pipe 9 and a fuel inlet pipe 10 at its upper and lower ends, respectively. The diameter of the fuel outlet pipe 9 is larger than the width of the upper spiral guide band 5, and the diameter of the fuel inlet pipe 10 is larger than the width of the lower spiral guide band 6.

[0027] In this embodiment of the invention, the extrusion-type rocket Laval nozzle of the present invention is manufactured based on a mature industrial manufacturing system, and its preparation method is as follows.

[0028] The combustion chamber 3, converging section 4, diffuser nozzle 2, upper seal 7, lower seal 8, upper spiral guide band 5, and lower spiral guide band 6 are all made of 304 stainless steel plate. This material has strong corrosion resistance, temperature resistance, and pressure resistance. The manufacturing equipment selected includes a three-roll plate rolling machine, an automatic circumferential welding machine, and a hydraulic forging press, all of which are commonly used in nuclear power equipment, pressure vessels, shipbuilding, and new energy equipment. Through mature processes such as rolling, circumferential welding, and forging, the combustion chamber 3 and converging section 4, as well as the upper spiral guide band 6, are manufactured. The integrated semi-finished prototype of seal 7 and the integrated semi-finished prototype of diffuser nozzle 2 and lower seal 8 are machine-welded and then forged after welding. In addition, the upper spiral guide belt 5 is wound around the outer wall of combustion chamber 3 and convergent section 4, and the lower spiral guide belt 6 is wound around the outer wall of diffuser nozzle 2, using a commonly used spiral coiling machine and hydraulic tensioning machine. The lower spiral guide belt 6 only covers the main body of diffuser nozzle 2, and its neck section is left empty, ensuring that the upper spiral guide belt 5 and the lower spiral guide belt 6 do not come into contact.

[0029] The forging process involves forging the weld seams immediately after all circumferential welds are completed, using a forging press while the weld seams are still hot. This process refines the weld grains and improves strength and sealing, avoiding the problems of cracking and leakage that are common in traditional nozzle weld seams. The arc-shaped structure of the forging press head is adapted to the weld seam profile.

[0030] The integrated pipe structure refers to the welding and splicing of individual components manufactured in separate molding processes to form a unified Laval nozzle structure, with a spiral cooling channel inside the pipe wall. The specific steps are as follows: The combustion chamber 3 and diffuser nozzle 2 are placed in a cryogenic freezer and cooled to below -50°C, causing their outer diameters to shrink; the diffuser nozzle 2 is removed using a robotic arm and placed vertically, and the outer Laval tube 1 is coaxially fitted onto the outside of the diffuser nozzle 2 from top to bottom; the combustion chamber 3 is removed using a robotic arm and embedded into the upper end of the outer Laval tube 1 from top to bottom, so that the converging section 4 abuts against the neck section of the diffuser nozzle 2; after the combustion chamber 3 and diffuser nozzle 2 naturally warm up, their volumes expand, causing the upper spiral guide band 5 and the lower spiral guide band 6 to adhere to the inner wall of the outer Laval tube 1. After the integrated pipe structure is assembled, a spiral cooling channel naturally forms inside the pipe wall from bottom to top.

[0031] The entire pipe structure is sealed. A 30° nuclear power standard V-groove is opened at the joint between the converging section 4 and the neck section. A composite welding process of argon arc welding for the root pass and plasma welding for the cover pass is used for circumferential welding. The coaxiality of the outer edge of the upper seal 7 with the top of the outer Laval tube 1 and the coaxiality of the outer edge of the lower seal 8 with the bottom of the outer Laval tube 1 are adjusted and sealed using an automatic circumferential welding machine. The fuel outlet pipe 9 and the fuel inlet pipe 10 are respectively embedded into the pre-set mounting holes of the outer Laval tube 1 and welded. After the entire pipe structure is sealed, the Laval nozzle is connected to the injector and propellant tank for further test runs.

[0032] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A Laval extrusion nozzle for rockets based on a mature industrial manufacturing system, characterized in that, include: External Laval nozzle, combustion chamber, diffuser nozzle, upper spiral guide band and lower spiral guide band; The bottom of the combustion chamber has a converging section, and the top of the diffuser nozzle has a neck section. The converging section and the neck section are fixed together by circumferential welding. The outer Laval tube is coaxially sleeved on the outside of the connection structure between the combustion chamber and the diffuser nozzle; the outer Laval tube, combustion chamber, and diffuser nozzle are all made of stainless steel. The upper spiral guide strip and the lower spiral guide strip are made of flat steel. The upper spiral guide strip is wound around and welded to the outer wall of the combustion chamber according to a preset pitch, and the lower spiral guide strip is wound around and welded to the outer wall of the diffuser nozzle according to a preset pitch. The upper spiral guide strip and the lower spiral guide strip do not contact each other. The upper and lower spiral guide bands create a spiral cooling channel between the outer Laval tube and the combustion chamber and diffuser nozzle.

2. The extrusion-type Laval rocket nozzle based on a mature industrial manufacturing system according to claim 1, characterized in that, The combustion chamber has an annular upper seal on its top outer side, and the outer edge of the upper seal is fixed to the top of the outer Laval tube by circumferential welding. The diffuser nozzle has an annular lower seal on its bottom outer side, and the outer edge of the lower seal is fixed to the bottom of the outer Laval tube by circumferential welding.

3. The extrusion-type Laval nozzle for rockets based on a mature industrial manufacturing system as described in claim 1, characterized in that, The outer Laval tube has a fuel outlet pipe and a fuel inlet pipe on its upper and lower outer walls, respectively. The diameter of the fuel outlet pipe is larger than the width of the upper spiral guide band, and the diameter of the fuel inlet pipe is larger than the width of the lower spiral guide band.

4. A method for preparing an extrusion-type rocket Laval nozzle based on a mature industrial manufacturing system, applicable to the extrusion-type rocket Laval nozzle based on a mature industrial manufacturing system as described in any one of claims 1-3, characterized in that, include: Separate molding process, assembly of complete tube structure, and sealing of the complete tube structure.

5. The method for preparing a Laval extrusion rocket nozzle based on a mature industrial manufacturing system according to claim 4, characterized in that, The split molding preparation includes: Select stainless steel plates of a preset size and use a three-roll plate rolling machine to roll the combustion chamber, convergent section and diffuser nozzle respectively. The three parts are then machine-welded around the circumferential seam and subjected to post-weld forging treatment. The combustion chamber and the convergent section are circumferentially welded and then forged after welding to form an integral piece. Cut nuclear-grade stainless steel flat bars to the design dimensions, and prepare upper and lower spiral guide strips by winding them with a spiral coiling machine. The upper spiral guide strip is wound and welded to the outer wall of the combustion chamber and the converging section, and the lower spiral guide strip is wound and welded to the outer wall of the diffuser nozzle. The annular upper and lower seals are manufactured using a stamping process. The upper seal is welded to the top of the combustion chamber, and the lower seal is welded to the bottom of the diffuser nozzle.

6. The method for preparing an extrusion-type rocket Laval nozzle based on a mature industrial manufacturing system according to claim 4, characterized in that, The forging process is as follows: After all circumferential welds are completed, forging should be carried out immediately while the weld is still hot using a forging press, with the arc-shaped structure of the forging press head matching the weld contour.

7. The method for preparing a Laval extrusion rocket nozzle based on a mature industrial manufacturing system according to claim 4, characterized in that, The complete pipe structure assembly includes: The combustion chamber and diffuser nozzle are cooled to below -50°C, causing their outer diameters to shrink. Remove the diffuser nozzle and place it vertically. Then, coaxially fit the outer Laval tube onto the outside of the diffuser nozzle from top to bottom. Remove the combustion chamber and insert it from top to bottom into the upper end of the outer Laval nozzle, so that the converging section abuts against the neck section of the diffuser nozzle; After the combustion chamber and diffuser nozzle naturally cool down, their volumes expand, causing the upper and lower spiral guide bands to adhere to the inner wall of the outer Laval tube.

8. The method for preparing a Laval extrusion rocket nozzle based on a mature industrial manufacturing system according to claim 4, characterized in that, The sealing of the entire pipe structure includes the following steps: A 30° nuclear power standard V-groove is opened at the junction of the converging section and the neck section, and a composite welding process of argon arc welding for the root pass and plasma welding for the cover pass is used for circumferential welding. Adjust the coaxiality between the outer edge of the upper seal and the top of the outer Laval tube, and the coaxiality between the outer edge of the lower seal and the bottom of the outer Laval tube, and perform sealing welding using an automatic circumferential welder; The fuel outlet pipe and fuel inlet pipe are respectively inserted into the pre-set mounting holes of the outer Laval pipe and then welded.

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