Lightweight cross-scale double-low-temperature injector and 3D printing manufacturing method

Abstract

The invention relates to the technical field of fluid machinery, and discloses a lightweight cross-scale double-low-temperature inspirator which comprises a disc-shaped upper liquid collecting disc and a butterfly-shaped lower liquid collecting device, and four cavities of the upper liquid collecting disc correspondingly communicate with four annular cavities of the lower liquid collecting device; each annular cavity of the lower liquid collector is provided with two groups of annularly arranged nozzles, and the nozzles are perpendicular to the surfaces of the annular cavities where the nozzles are located. The invention further provides a 3D printing method of the injector, firstly, multi-scale three-dimensional modeling is carried out and divided into a macroscopic structure layer and a microcosmic feature layer, then layered printing is carried out, and when interface transition areas of different materials are printed, integrated forming of the multifunctional gradient material is achieved through material alternate deposition. According to the injector, low-temperature sufficient gasification and efficient combustion of fuel are guaranteed structurally, the cross-scale 3D printing technology adopted in manufacturing supports integrated forming of a complex internal flow channel and a functional structure, and the hydrodynamic performance and the combustion efficiency are further improved.

Description

Technical Field

[0001] This invention belongs to the field of fluid machinery technology, specifically relating to a lightweight, multi-scale dual cryogenic injector and a 3D printing manufacturing method. Background Technology

[0002] As aerospace propulsion systems evolve towards high performance and reusability, liquid methane (LCH4) / liquid oxygen (LOX) combinations have become ideal fuels for next-generation cryogenic engines due to their advantages such as high specific impulse, low coking, and good propellant compatibility. However, traditional injectors face a series of challenges when used with such cryogenic propellants.

[0003] I. Combustion Efficiency Issues: Under 6MPa high pressure and ultra-low temperature conditions (methane -182℃, oxygen -183℃), the shrinkage characteristics of materials and changes in fluid viscosity lead to decreased atomization uniformity and lower combustion efficiency. Traditional injectors struggle to achieve complete fuel vaporization and efficient combustion in low-temperature and high-pressure environments.

[0004] II. Combustion instability risk: The wide distillation range of methane can easily cause delayed liquid phase breakup and pressure oscillations during mixing with oxygen, threatening the safety of the engine structure. Existing designs are unable to effectively suppress combustion instability in low-temperature environments, increasing the risk of engine operation.

[0005] 3. Uneven atomization particle size distribution: Existing DC / centrifugal injectors struggle to achieve fine atomization with a Sottle mean diameter (SMD) of <50μm under high pressure, affecting the combustion reaction rate. In low-temperature environments, uneven atomization particle size distribution further reduces combustion efficiency.

[0006] IV. Lightweight Requirements: Traditional injectors often employ a multi-part assembly structure, which not only increases overall weight and complexity but also reduces structural strength and reliability. Existing injector designs, while meeting low-temperature, high-pressure performance requirements, often struggle to meet lightweight requirements, leading to an increase in overall engine weight and impacting its performance and fuel economy.

[0007] V. Cross-Scale Design Challenges: Injector performance optimization requires collaborative design at both macro and micro scales. At the macro scale, the injector needs to meet overall structural strength, flow channel layout, and thermal management requirements; at the micro scale, the structure, size, and distribution of the injection orifices directly affect atomization and combustion efficiency. Furthermore, in cryogenic and high-pressure environments, cross-scale design must also consider the material's coefficient of thermal expansion, hydrodynamic characteristics, and manufacturing process feasibility. Current injector designs are mostly optimized for kerosene or hydrogen fuels, and directly transplanting them to methane / oxygen systems presents inherent limitations. Therefore, a novel injector specifically designed for LCH4 / LOX high-pressure cryogenic conditions needs to be developed. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a lightweight, multi-scale dual cryogenic injector and a 3D printing manufacturing method, so as to use 3D integrated printing to create a new type of injector specifically for LCH4 / LOX high-pressure cryogenic conditions, achieving lightweight, efficient atomization and high combustion efficiency of the injector while ensuring combustion stability.

[0009] To address the aforementioned technical problems, this invention provides a lightweight, multi-scale, dual cryogenic injector, comprising an upper collecting plate and a lower collecting device arranged coaxially. The upper collecting plate is divided into four chambers from the inside out, wherein the second and fourth chambers are interconnected to form an upper fuel chamber, and the first and third chambers are interconnected to form an upper oxidizer chamber. A first injection port and a second injection port are provided on the upper collecting plate, the first injection port being connected to the upper fuel chamber and the second injection port being connected to the upper oxidizer chamber.

[0010] The lower liquid collector is disc-shaped and divided into four isolated annular cavities from the inside out; the four cavities of the upper liquid collector are connected to the four annular cavities of the lower liquid collector through connecting pipes.

[0011] The lower liquid collector has a downward-facing dish-shaped opening, and each annular cavity is equipped with two sets of nozzles arranged in a circular pattern.

[0012] As an improvement of the present invention, a lightweight, multi-scale dual cryogenic injector is as follows:

[0013] The nozzle has auxiliary jet holes evenly arranged circumferentially; the nozzle is perpendicular to the surface of its respective annular cavity.

[0014] As a further improvement to the lightweight, multi-scale dual cryogenic injector of the present invention:

[0015] The first cavity of the upper liquid collection plate is circular, the second and third cavities are C-shaped, and the fourth cavity is annular. The side walls of the C-shaped heads of the second and third cavities are composed of tangent circular arcs.

[0016] The first and second annular cavities of the lower liquid collector are located on the bottom surface of the dish and are parallel to the upper liquid collecting plate, while the third and fourth annular cavities are located on the curved surface of the dish and form a 45° angle with the upper liquid collecting plate.

[0017] This invention also provides a 3D printing method for a lightweight, multi-scale dual cryogenic injector, comprising the following steps:

[0018] S1. Multi-scale three-dimensional modeling of the lightweight multi-scale dual cryogenic injector is performed. The three-dimensional model is divided into a macroscopic structural layer and a microscopic feature layer. Then, the structure is optimized by topology optimization and simulation analysis.

[0019] S2. The optimized 3D model is sliced ​​into layers, and different layer thicknesses are assigned to the macroscopic structure layer and the microscopic feature layer, and the optimal laser scanning path is planned for each layer.

[0020] S3. After calibrating the printing equipment, selective laser melting (SLM) technology is used for layer printing. The macroscopic structure layer is printed using the first combination of process parameters, and the microscopic feature layer is printed using the second combination of process parameters. In-situ quality inspection is performed during the printing process, and process parameters are adjusted in real time.

[0021] S4. When printing the interface transition area of ​​different materials, the integrated molding of multifunctional gradient materials is achieved by alternating material deposition.

[0022] S5. After printing, perform segmented temperature-controlled gradient heat treatment, surface treatment, and performance testing.

[0023] An improvement to the 3D printing method of a lightweight, multi-scale dual cryogenic injector as described in this invention:

[0024] The three-dimensional model includes a lightweight, multi-scale dual cryogenic injector divided into three layers from the outside to the inside: an outer shell region, a sealing connection region, and an internal flow channel region. The outer shell region is further divided into an inlet region, a main load-bearing frame region, and a nozzle region. The inlet region is located at the location of the first and second injection ports. The main load-bearing frame region is located at the location of the upper liquid collection tray, connecting pipe, and lower liquid collector. The nozzle region is located at the location of the nozzle.

[0025] The core dimensions of the macroscopic structural layer range from 0.1mm to 10mm, including the inlet region, the main load-bearing frame region, and the sealing connection region. The core dimensions of the microscopic feature layer range from 1μm to 100μm, including the internal flow channel region and the nozzle region.

[0026] As a further improvement to the 3D printing method of the lightweight multi-scale dual cryogenic injector of the present invention:

[0027] The first combination of process parameters includes: laser power of 300-400W, spot diameter of 80-100µm, layer thickness of 40-60µm, and scanning speed of 800-1200mm / s;

[0028] The second combination of process parameters includes: laser power of 70-150W, spot diameter of 20-40µm, layer thickness of 10-25µm, and scanning speed of 400-600mm / s.

[0029] As a further improvement to the 3D printing method of the lightweight multi-scale dual cryogenic injector of the present invention:

[0030] The thickness of the macroscopic structure layer is 40-60 μm, and the thickness of the microscopic feature layer is 10-25 μm;

[0031] The optimal laser scanning path is planned by employing a long vector chessboard partitioning strategy for the macroscopic structural layer and a contour offset and short vector filling strategy for the microscopic feature layer.

[0032] As a further improvement to the 3D printing method of the lightweight multi-scale dual cryogenic injector of the present invention:

[0033] The integrated molding method for the multifunctional gradient material is as follows:

[0034] When the printing interface transitions from one functional area to another, within the transition area, the laser power is gradually adjusted from the typical value of the initial material to the typical value of the target material using a gradient adjustment method. At the same time, the scanning speed is adjusted synchronously, forming a metallurgical bonding transition zone at the interface. The microstructure of the metallurgical bonding transition zone exhibits a continuous compositional gradient change.

[0035] As a further improvement to the 3D printing method of the lightweight multi-scale dual cryogenic injector of the present invention:

[0036] The in-situ quality inspection includes real-time monitoring of the printing status, adjusting the laser power and scanning speed when abnormal melt pool temperature is detected, and adaptively adjusting the powder feed amount or initiating secondary finishing of local areas when geometric defects are detected.

[0037] As a further improvement to the 3D printing method of the lightweight multi-scale dual cryogenic injector of the present invention:

[0038] The gradient heat treatment involves setting up segmented temperature control zones, and carrying out differentiated aging treatments for the nozzle area, inlet area, internal flow channel area, main load-bearing frame area, and sealing connection area respectively.

[0039] The surface treatment includes surface polishing of the internal flow channel area and surface high-temperature and corrosion-resistant coating treatment of the nozzle area.

[0040] The beneficial effects of this invention are mainly reflected in:

[0041] 1. This invention employs a structural design for the upper liquid collection tray with a gradually curved arc wall. By optimizing stress distribution, it significantly improves the stiffness and stability of the injector. It effectively addresses material stress changes caused by low-temperature contraction and high-pressure expansion, offering higher load-bearing capacity and overall structural strength compared to traditional flat-wall designs. This innovation not only enhances the reliability of the injector under extreme conditions but also extends its service life, providing a safer and more stable solution for complex engineering applications.

[0042] 2. This invention employs a disc-shaped lower liquid collector design, increasing the injection area and allowing for the arrangement of more rings and nozzles. Simultaneously, the curved nozzle arrangement reduces axial velocity, increases vaporization length and combustion turbulence, thereby improving combustion efficiency. Compared to planar injectors, it eliminates the pressure unevenness problem caused by uneven radial mass distribution, ensuring complete fuel vaporization and efficient combustion at low temperatures, further enhancing combustion stability and overall performance.

[0043] 3. The nozzle of this invention employs a structural design with multiple sets of auxiliary jet holes on the main body sidewall. The lateral jets and the main jet form a high-speed shear layer, tearing the initial liquid film through momentum exchange, resulting in more complete atomization. In low-temperature environments, it can effectively overcome the low-temperature and high-viscosity characteristics of liquid oxygen and liquid methane, achieving a more uniform atomization effect and significantly improving combustion efficiency. Compared with existing technologies, this innovative design has significant advantages in low-temperature atomization effect and combustion efficiency, providing a new technical path for the efficient utilization of low-temperature fuels.

[0044] 4. This invention employs a multifunctional gradient material manufacturing method based on cross-scale 3D printing. By precisely controlling the material composition and microstructure of different parts, the performance of the injector is optimized. In high-temperature and high-pressure regions (such as the nozzle region), GRX-810 ODS alloy is used to enhance high-temperature strength and creep resistance; in low-temperature regions (such as the inlet region), a nickel-based alloy with better low-temperature toughness is used to improve brittleness resistance and low-temperature adaptability. Through material gradient design, the injector achieves synergistic performance optimization at both the macroscopic and microscopic scales, meeting the strength requirements under high-temperature and high-pressure environments while ensuring structural stability under low-temperature environments. This material gradient design method provides a novel solution for the reliability and performance of injectors under extreme conditions, offering higher overall performance and broader application prospects compared to existing technologies.

[0045] 5. The cross-scale 3D printing technology used in this invention supports the integrated molding of complex internal flow channels and functional structures, further improving fluid dynamics performance and combustion efficiency. Attached Figure Description

[0046] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0047] Figure 1 This is a schematic diagram of the overall structure of a lightweight, multi-scale dual cryogenic injector according to the present invention;

[0048] Figure 2 This is a side view of a lightweight, multi-scale dual cryogenic injector according to the present invention;

[0049] Figure 3 This is a side sectional view of a lightweight, multi-scale, dual cryogenic injector according to the present invention;

[0050] Figure 4 (a) is a bottom view of a lightweight multi-scale dual cryogenic injector of the present invention, and (b) is a top view of a lightweight multi-scale dual cryogenic injector.

[0051] Figure 5 This is a schematic diagram of the nozzle of the present invention;

[0052] Figure 6 This is a schematic diagram illustrating the functional area division of a lightweight, multi-scale dual cryogenic injector according to the present invention.

[0053] Figure 7 This is a diagram showing the correspondence between the functional regions and materials of a lightweight, multi-scale, dual cryogenic injector according to the present invention.

[0054] Figure 8 This is a flowchart of a 3D printing manufacturing method for a lightweight, multi-scale, dual cryogenic injector according to the present invention.

[0055] Figure 9 This is a simulation cloud map of a lightweight, multi-scale, dual cryogenic injector atomization according to the present invention.

[0056] Figure 10 This is a simulated cloud map of a conventional configuration atomization. Detailed Implementation

[0057] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto:

[0058] Example 1: A lightweight, multi-scale dual cryogenic injector, such as... Figures 1-5 As shown, it consists of a first injection port 1, a second injection port 2, an upper liquid collection plate 3, a connecting pipe 4, a lower liquid collector 5, and a nozzle 6. The upper liquid collection plate 3 and the lower liquid collector 5 are arranged coaxially, one above the other.

[0059] The upper liquid collecting plate 3 is equipped with a first injection port 1 and a second injection port 2. The upper liquid collecting plate 3 is generally disc-shaped, as shown below. Figure 4As shown in (b), the device is divided into four concentric cavities from the inside out, with the first cavity 31 at the center and the fourth cavity 34 on the outside. The first cavity 31 is circular, the second cavity 32 and the third cavity 33 are C-shaped, and the fourth cavity 34 is annular. The second cavity 32 and the fourth cavity 34 are interconnected to form the upper fuel cavity 7, and the first injection port 1 is connected to the upper fuel cavity 7 to introduce the propellant (liquid methane). The first cavity 31 and the third cavity 33 are interconnected to form the upper oxidizer cavity 8, and the second injection port 2 is connected to the upper oxidizer cavity 8 to introduce the oxidizer (liquid oxygen). From a structural mechanics perspective, the sidewalls of the C-shaped heads of the second cavity 32 and the third cavity 33 are composed of tangent circular arcs, ensuring that there are no abrupt changes or sharp corners at all connections, achieving continuous curvature of the geometric shape. By optimizing the stress distribution, the stiffness and stability of the injector are significantly improved. This gradually curved wall design efficiently disperses and redistributes the concentrated stress caused by low-temperature contraction and high-pressure expansion, avoiding the stress concentration problem at corners inherent in traditional flat wall designs. This improves the overall stiffness, structural stability, and load-bearing capacity of the injector under extreme conditions. This innovation not only enhances the reliability of the injector under extreme conditions but also extends its service life, providing a safer and more stable solution for complex engineering applications.

[0060] The lower liquid collector 5 is located below the upper liquid collecting plate 3 and has a disc-shaped structure with the disc opening facing downwards. The lower liquid collector 5 includes four mutually isolated annular cavities, such as... Figure 4 As shown in (a), the first annular cavity 51 is circular at its center, and from the inside out, there are sequentially circular second annular cavities 52, third annular cavities 53, and fourth annular cavities 54. Among them, the first annular cavity 51 and the second annular cavity 52 are located on the bottom surface of the dish and are parallel to the upper liquid collecting plate 3, while the third annular cavity 53 and the fourth annular cavity 54 are located on the curved surface of the dish and form a 45° angle with the upper liquid collecting plate 3. The four cavities of the upper liquid collecting plate 3 are respectively connected to the four annular cavities of the lower liquid collecting device 5 via connecting pipes 4 (i.e., the first cavity 31 of the upper liquid collecting plate 3 is connected to the first annular cavity 51 of the lower liquid collecting device 5, the second cavity 32 of the upper liquid collecting plate 3 is connected to the second annular cavity 52 of the lower liquid collecting device 5, and so on). The connecting pipes 4 are used to introduce the propellant (liquid methane) into the second annular cavity 52 and the fourth annular cavity 54 of the lower liquid collecting device 5, and to introduce the oxidant (liquid oxygen) into the first annular cavity 51 and the third annular cavity 53 of the lower liquid collecting device 5. They also serve to connect and fix the upper liquid collecting plate 3 and the lower liquid collecting device 5 together. The lower liquid collecting device 5 of this invention adopts a disc-shaped structural design, which increases the injection area and allows for the arrangement of more rings and nozzles. At the same time, the curved surface of the nozzle arrangement reduces the axial velocity, increases the vaporization length and combustion turbulence, thereby improving combustion efficiency.

[0061] The coaxial nested four-ring double-layer liquid collection chamber design of the upper liquid collecting plate 3 and the lower liquid collecting device 5 adjusts the correspondence between the inlet channel and the nozzle 6, resulting in an alternating "oxidizer-fuel-oxidizer-fuel" phase distribution pattern of oxidizer and fuel on the outlet plane of the nozzle 6. This increases the contact area between the two phases on a macroscopic scale, creating optimal initial conditions for subsequent atomization and mixing, thereby effectively promoting rapid and uniform mixing and laying the foundation for improved combustion efficiency.

[0062] Each annular cavity of the lower liquid collector 5 is provided with two sets of circularly arranged nozzles 6, which are connected to the inner cavity of their respective annular cavities. The angle between the nozzles 6 and the lower liquid collector 5 can be adjusted according to actual working conditions. In this embodiment, the nozzles 6 are arranged perpendicularly to the surface of their respective annular cavities. Multiple sets of auxiliary jet holes are formed on the main sidewall of the nozzle 6. In this embodiment, four sets of auxiliary jet holes are evenly arranged circumferentially for each nozzle 6, and each set contains nine auxiliary jet holes. This invention adopts a structural design with multiple sets of auxiliary jet holes on the sidewall of the nozzle main body. The lateral jet and the main jet form a high-speed shear layer, which tears the initial liquid film through momentum exchange, resulting in more complete atomization.

[0063] The working process of a lightweight, multi-scale dual cryogenic injector of the present invention is as follows: a propellant (liquid methane) is introduced into the first injection port 1, and an oxidant (liquid oxygen) is introduced into the second injection port 2, flowing into the upper fuel chamber 7 (the second chamber 32 and the fourth chamber 34 of the upper liquid collecting plate 3) and the upper oxidant chamber 8 (the first chamber 31 and the third chamber 33 of the upper liquid collecting plate 3), respectively. The propellant (liquid methane) in the upper fuel chamber 7 flows into the second annular chamber 52 and the fourth annular chamber 54 of the lower liquid collector 5 through the connecting pipe 4, and the oxidant (liquid oxygen) in the upper oxidant chamber 8 flows into the first annular chamber 51 and the third annular chamber 53 of the lower liquid collector 5 through the connecting pipe 4, and then is sprayed out through the nozzle 6, where it is atomized, mixed, and combusted in the thrust chamber.

[0064] The functional area division of a lightweight, multi-scale dual cryogenic injector according to the present invention is as follows: Figure 6As shown, the system is divided into three functional areas from the outside in: the outer shell area P1, the sealing connection area P2, and the internal flow channel area P3. The outer shell area P1 is the main load-bearing structure and external boundary of the injector, and can be further divided into the inlet area P11, the main load-bearing frame area P12, and the nozzle area P13. The inlet area P11 is located at the uppermost part of the outer shell area P1, mainly including the locations of the first injection port 1 and the second injection port 2. It is responsible for receiving and initially distributing the cryogenic propellant. This area needs to possess excellent cryogenic toughness and structural stability to resist the risk of brittle fracture under extreme cryogenic conditions. The main load-bearing frame area P12 is located in the middle of the outer shell area P1, mainly including the upper liquid collection plate 3, the connecting pipe 4, and the lower liquid collector 5. It is the main structural part connecting the inlet area P11 and the nozzle area P13. Its main function is to bear the main mechanical loads such as the internal pressure and vibration loads of the injector. Therefore, it needs to have high rigidity and strength, while achieving structural lightweighting under these conditions. The nozzle region P13 is located at the downstream end of the outer shell region P1, where nozzle 6 is located, and directly faces the high-temperature and high-pressure environment of the combustion chamber. It must maintain excellent high-temperature strength, creep resistance, and oxidation resistance to ensure the integrity of its morphology and function in the flame environment. The sealing connection region P2 is a functional area located between the outer shell region P1 and the internal flow channel region P3. Its core task is to ensure the absolute sealing integrity of the system under extreme operating conditions. This functional area needs high thermal conductivity to balance thermal stress, good low-temperature toughness and plasticity to accommodate structural deformation, and sufficient strength to maintain effective sealing pressure. The internal flow channel region P3 is in direct contact with the propellant and must have excellent corrosion resistance and a smooth flow channel surface to reduce flow resistance and ensure fluid transmission efficiency.

[0065] This invention discloses a lightweight, multi-scale dual cryogenic injector manufactured using 3D printing technology. Employing a multi-scale design, it utilizes a gradient multi-material scheme matching different materials to different functional areas. This reduces the development cost of the lightweight, multi-scale dual cryogenic injector, improves production efficiency, significantly shortens the production cycle, and contributes to enhanced product reliability and yield. Furthermore, the integrated structural design reduces many manual steps such as welding and bonding, creating conditions for automated batch production of the lightweight, multi-scale dual cryogenic injector. The specific process is as follows... Figure 8 As shown:

[0066] 1. Initial Requirements Analysis

[0067] In the initial stage of multi-scale, multi-layer 3D printing, a comprehensive analysis of the injector's functional requirements, operating conditions, and performance targets is necessary. The core functions of the injector in liquid oxygen and methane must be clearly defined, such as efficient atomization, combustion stability, and lightweighting. The operating conditions of the injector under extreme low temperatures (liquid methane -182℃, liquid oxygen -183℃) and high pressures (6MPa level) must be analyzed. Key performance indicators of the injector must be determined, such as Sottle mean diameter (SMD < 50μm), combustion efficiency, structural strength, and fatigue resistance. Based on functional requirements and operating conditions, suitable high-performance materials should be preliminarily screened. Figure 7 As shown, this invention divides the hot-air injector into three functional zones from the outside in. For each functional zone, a combination of high-performance materials is used to meet performance requirements under extreme operating conditions. Specifically:

[0068] Inlet area P11: Made of Inconel 718, a nickel-based alloy with excellent low-temperature toughness. This material exhibits excellent resistance to brittleness (fracture toughness ≥100MPa·m^1 / 2) and structural stability at low temperatures, which can effectively prevent the injector from brittle fracture in the low-temperature environment of liquid oxygen and methane, ensuring its safe operation under extreme low-temperature conditions.

[0069] Main load-bearing frame area P12: Uses titanium alloy Ti-6Al-4V, which has high specific strength (≥900MPa) and excellent stiffness, while achieving lightweight design, reducing the overall weight of the injector, adapting to mechanical stress under extreme working conditions, and improving the overall structural strength and durability.

[0070] Nozzle area P13: Utilizes GRX-810 ODS alloy, a material with excellent high-temperature strength (tensile strength ≥1200MPa), oxidation resistance, and creep resistance, maintaining mechanical properties under extreme high-temperature (≥1000℃) and high-pressure (≥6MPa) environments. Its optimized microstructure effectively inhibits grain growth, further improving the material's fatigue resistance and ensuring the reliability of the injector under complex operating conditions.

[0071] Sealed connection area P2: Made of copper-based alloy C18150. This material has good thermal conductivity (thermal conductivity ≥200W / m·K) and sealing performance, which can effectively adapt to thermal stress changes under extreme working conditions, improve the overall reliability and thermal management efficiency of the injector, and ensure the stability of system operation.

[0072] Internal flow channel area P3: Made of 316L stainless steel. This material has excellent corrosion resistance (corrosion rate ≤0.01mm / year) and fluid dynamics performance, which can optimize fluid transmission efficiency, reduce energy loss, and ensure long-term stable operation of the injector in complex media environments, thereby reducing maintenance costs.

[0073] 2. Multi-scale modeling

[0074] Based on the initial requirements, a multi-scale 3D model of the injector was constructed, covering both the macroscopic structural layer and the microscopic feature layer:

[0075] Macroscopic structural layer: The part with core dimensions ranging from 0.1mm to 10mm, including the inlet area P11, the main load-bearing frame area P12, and the sealed connection area P2.

[0076] Microscopic feature layer: The core scale ranges from 1μm to 100μm, including the internal flow channel region P3 and the nozzle region P13.

[0077] 3. Topology Optimization and Simulation

[0078] Through topology optimization and simulation analysis, the structural design and performance of the injector were further optimized.

[0079] Topology optimization: Finite element analysis (FEA) is used to optimize the topology of the injector structure. FEA can discretize a complex, continuous geometry into a finite number of simple, tiny elements. By assigning material properties, applying loads and constraints, it calculates the stress, strain, and displacement field distribution of the structure under working conditions, thereby accurately identifying high-stress critical areas and low-stress redundant areas. Then, while meeting strength requirements, the material in the low-stress area P1 of the outer shell is iteratively removed to generate an optimal material distribution scheme characterized by lattice structures or biomimetic ribs, achieving lightweighting under the same load.

[0080] Simulation Analysis: Fluent software was used to simulate the injector's operation under low temperature and high pressure to verify its atomization effect and combustion efficiency. Based on the results, the following design parameters were optimized and adjusted: nozzle diameter, number, length, and installation angle; area of ​​the liquid collection chamber and the included angle of the disc-shaped curved surface; and nozzle diameter. For example, while keeping other conditions constant, simulations were performed comparing three nozzle installation angles of 40°, 45°, and 50°, and the final scheme was selected based on performance.

[0081] 4. Layered Slicing and Path Planning

[0082] The optimized 3D model is sliced ​​into layers, and printing paths are planned. First, an adaptive layering algorithm discretizes the model into a series of 2D sections along the forming direction, and different layer thicknesses are allocated according to the scale difference between the macroscopic structural layer and the microscopic feature layer (40-60μm for macroscopic structural layer; 10-25μm for microscopic feature layer). Then, for the feature requirements of different regions, the optimal laser scanning path is planned respectively—the macroscopic structural layer adopts a long vector chessboard partitioning strategy to improve efficiency and control thermal stress, while the microscopic feature layer adopts a contour offset and short vector filling strategy to ensure feature accuracy and surface quality. Finally, the key instruction set that drives the printing device to perform cross-scale forming is generated.

[0083] 5. Printing equipment calibration

[0084] Before the actual printing, the 3D printing equipment is calibrated to ensure printing accuracy and stability. First, the working status of core hardware components such as the optical system, powder delivery system, and motion platform is checked. Second, based on material properties and printing requirements, process parameters such as laser power, spot diameter, layer thickness, and scanning speed are adjusted to ensure print quality. Small-scale trial printing is conducted to verify the equipment calibration effect, and parameters are optimized based on the trial printing results. If defects such as spheroidization or lack of fusion are found, the laser power is appropriately increased or the scanning speed is decreased to increase energy input; if over-melting or thermal stress deformation occurs, the opposite adjustment is made to reduce energy. Through this iterative process, the optimal parameter combination is finally determined.

[0085] 6. Layered printing

[0086] Using selective laser melting (SLM) technology, the inkjet printer is printed layer by layer:

[0087] Macroscopic structural layer printing: A combination of high laser power (300-400W), large spot diameter (80-100μm), thick layer (40-60μm), and fast scanning speed (800-1200mm / s) is used to ensure the strength and forming efficiency of the main structure.

[0088] Microscopic feature layer printing: The process combination of low laser power (70-150W), small spot diameter (20-40μm), thin layer (10-25μm) and slow scanning (400-600mm / s) ensures the detail accuracy and surface quality of internal flow channels and auxiliary jet holes.

[0089] Alternating Material Deposition: Different powders are deposited alternately according to the material requirements of functional areas to achieve integrated molding of multifunctional gradient materials. Alternating material deposition is achieved through programmed control of the powder delivery system and laser scanning strategy, precisely laying the corresponding metal powder in different functional areas of the injector. When the printing interface transitions from one functional area to another (i.e., from one material to another, such as from GRX-810 ODS alloy to copper-based alloy C18150), a power gradient change program is initiated: in the transition area (usually designed for 3-5 printing layers, 0.5-1mm wide), the laser power is gradually adjusted from the typical value of the initial material (e.g., 300W) at a gradient of 50-80W / layer to the typical value of the target material (e.g., 150W), while the scanning speed is adjusted synchronously (gradually decreasing from 800mm / s to 500mm / s). This progressive energy control ensures sufficient atomic interdiffusion between dissimilar materials in the molten pool, forming a metallurgical bonding transition zone with a thickness of about 100-200 μm at the interface. Its microstructure exhibits a continuous compositional gradient change, thereby effectively eliminating defects such as the formation of brittle phases and residual stress concentration at the bonding interface caused by differences in thermophysical properties, and ensuring the interface stability and structural integrity of the gradient material under extreme thermal cycling conditions.

[0090] 7. In-situ quality inspection

[0091] During the printing process, print quality is monitored in real time to ensure the structural integrity and accuracy of each layer: high-precision sensors and cameras are used to monitor the printing status of each layer in real time and detect any defects or deviations. When defects are found, the system adjusts process parameters in real time based on in-situ monitoring data: when the melt pool temperature is abnormal, the laser power (±5-10%) and scanning speed (±50-100mm / s) are dynamically adjusted; when geometric defects are identified, the powder feed is adaptively adjusted or a secondary finishing process is initiated in the local area.

[0092] 8. Heat treatment

[0093] After printing, the nozzle undergoes gradient heat treatment, which involves segmented temperature control for different material areas during a single heat treatment process. Multiple segmented temperature control zones are set up, and differentiated aging treatments are applied to the nozzle area P13, inlet area P11, internal flow channel area P3, main load-bearing frame area P12, and sealing connection area P2 to optimize overall performance. The specific process is as follows: the entire nozzle is heated to 1050℃-1100℃ for solution treatment and held at that temperature for 1-1.5 hours to eliminate residual stress and homogenize the microstructure. Subsequently, the nozzle area P13 (GRX-810 ODS alloy) was aged at 750℃-800℃ for 4-6 hours; the inlet area P11 (nickel-based alloy Inconel 718) was aged at 700℃-750℃ for 3-5 hours; the internal flow channel area P3 (316L stainless steel) was aged at 600℃-650℃ for 2-4 hours; the main load-bearing frame area P12 (titanium alloy Ti-6Al-4V) was aged at 500℃-550℃ for 4-6 hours; and the sealing connection area P2 (copper-based alloy) was aged at 400℃-450℃ for 2-3 hours. The entire heat treatment process was carried out in an inert gas or vacuum environment to ensure stable material properties, ultimately achieving high strength, corrosion resistance, and fatigue resistance for the entire injector under extreme operating conditions.

[0094] 9. Surface treatment

[0095] Surface treatment of the injector: Mechanical or chemical polishing is performed on the inner wall surface (i.e., the surface of the internal flow channel region P3) to reduce surface roughness, decrease fluid resistance, and optimize its hydrodynamic performance and corrosion resistance. A high-temperature and corrosion-resistant coating is applied to the surface of the nozzle region P13 to further enhance its performance.

[0096] 10. Performance Testing

[0097] A comprehensive performance test was conducted on the printed nozzles, and their adaptability to extreme working conditions was verified through quantitative testing: In terms of mechanical properties, the tensile strength of the sample at -196℃ must be ≥900MPa, and the high-cycle fatigue life (±350MPa stress amplitude) must be greater than 10. 7 The cycle is repeated; in terms of fluid and combustion performance, the flow uniformity of each nozzle is ≤±3% under a pressure difference of 6MPa, the average diameter of the atomized Sottle (SMD) is <50μm and the combustion efficiency is ≥98.5%; in terms of environmental reliability, the injector must pass a sealing test at -183℃ / 6MPa for 30 minutes, 1000 cycles of thermal shock from -180℃ to 800℃ and random vibration test at 20-2000Hz. All indicators must meet the design thresholds to ensure its long-term operational reliability in a liquid oxygen / methane environment.

[0098] 11. Design Optimization

[0099] Based on the performance test results, the design of the injection nozzle is optimized: defects found during testing are analyzed to identify shortcomings in design or manufacturing. Printing process parameters, material combinations, or structural designs are optimized to further improve the performance of the injection nozzle. Through multiple iterative optimizations, the injection nozzle is ultimately able to operate efficiently, stably, and reliably under extreme conditions.

[0100] experiment:

[0101] Under the same conditions of a single nozzle diameter of 0.2 mm and a total mass flow rate of 240 g / s, the lightweight multi-scale dual cryogenic injector manufactured using 3D printing technology in Embodiment 1 of the present invention was compared with the conventional configuration using the fluid simulation software Fluent. This was to verify the optimization of the injector of the present invention in terms of structure and mass, as well as the improvement in the spatial expansion and dispersion of the spray field compared with the conventional configuration.

[0102] (1) The injector of Embodiment 1 of the present invention has a disc-shaped structure, with the curved surface of the disc forming a 45° angle with the upper liquid collecting plate, and a total of 240 nozzles. In the conventional configuration, the lower liquid collecting device is a flat plane with a total of 240 nozzles, and the nozzles are parallel to each other. With the same number of nozzles, the overall area of ​​the injector of Embodiment 1 of the present invention is approximately 430 mm². 2 Compared to the conventional configuration of 610mm 2 It reduces the size by about 30%; if the overall area is the same, the injector solution of the present invention can accommodate more nozzles.

[0103] (2) The injector of Embodiment 1 of the present invention adopts a multi-functional gradient material design. The conventional configuration adopts a single nickel-based high-temperature alloy (Inconel 718), which reduces the overall weight by about 30% and achieves the goal of lightweighting.

[0104] (3) The simulation uses an explicit VOF (Volume of Fluid) multiphase flow model to describe the evolution of the liquid-gas interface and an SST k-omega turbulence model (Shear Stress Transport k-ω turbulence model) to describe the turbulent transport behavior. To improve the interface resolution and ensure the calculation accuracy, a level 2 mesh adaptive refinement is enabled to accurately capture the gas-liquid interface. Figure 9 and Figure 10 The transient spray structures of the injector of Embodiment 1 of the present invention and a conventional configuration are shown respectively. The results show that the longitudinal velocity of the injector of Embodiment 1 is lower than that of the conventional configuration, with a maximum longitudinal velocity of approximately 25 m / s, compared to approximately 30 m / s for the conventional configuration. The atomization cone angle of the injector of Embodiment 1 is larger than that of the conventional configuration, approximately 25°, compared to approximately 21° for the conventional configuration. Embodiment 1 of the present invention exhibits superior spatial spread and dispersion, demonstrating its effective improvement in promoting fuel and oxidant mixing.

[0105] Finally, it should be noted that the above examples are merely some specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A lightweight, cross-scale, dual cryogenic injector, characterized by: The coaxial upper liquid collecting disc (3) and lower liquid collector (5) are arranged in upper and lower positions, the upper liquid collecting disc (3) is divided into four cavities from inside to outside, the second cavity (32) and the fourth cavity (34) are in communication to form an upper fuel cavity (7), the first cavity (31) and the third cavity (33) are in communication to form an upper oxidant cavity (8); the first injection port (1) and the second injection port (2) are arranged on the upper liquid collecting disc (3), the first injection port (1) is in communication with the upper fuel cavity (7), and the second injection port (2) is in communication with the upper oxidant cavity (8); The lower liquid collector (5) is disc-shaped and divided into four ring cavities isolated from each other from inside to outside; the four cavities of the upper liquid collecting disc (3) are in communication with the four ring cavities of the lower liquid collector (5) through the connecting pipes (4) respectively; The disc-shaped opening of the lower liquid collector (5) faces downward, and two groups of circularly arranged nozzles (6) are arranged on each ring cavity.

2. The lightweight cross-scale dual cryogenic injector according to claim 1, wherein: the nozzles (6) are uniformly arranged with auxiliary jet holes in the circumferential direction; and the nozzles (6) are perpendicular to the surfaces of the ring cavities in which the nozzles (6) are arranged.

3. The lightweight cross-scale dual cryogenic injector according to claim 2, wherein: the first cavity (31) of the upper liquid collecting disc (3) is circular, the second cavity (32) and the third cavity (33) are C-shaped, and the fourth cavity (34) is circular annular; the side wall surfaces of the C-shaped heads of the second cavity (32) and the third cavity (33) are composed of tangent circular arcs; the first ring cavity (51) and the second ring cavity (52) of the lower liquid collector (5) are located on the disc-shaped bottom surface and are parallel to the upper liquid collecting disc (3), and the third ring cavity (53) and the fourth ring cavity (54) are located on the disc-shaped curved surface and form a 45° angle with the upper liquid collecting disc (3). The method comprises the following steps, S1. Multi-scale three-dimensional modeling of the lightweight cross-scale dual cryogenic injector according to any one of claims 1-3, the three-dimensional model being divided into a macroscopic structure layer and a microscopic feature layer; 4. A 3D printing method of a lightweight cross-scale dual cryogenic injector, characterized by: Then, the structure is optimized by a method of topological optimization and simulation analysis; S2. Layered slicing of the optimized three-dimensional model, different layer thicknesses being assigned to the macroscopic structure layer and the microscopic feature layer, and optimal laser scanning paths being planned respectively; S3. After the printing equipment is calibrated, the macroscopic structure layer is printed using a first process parameter combination, and the microscopic feature layer is printed using a second process parameter combination by selective laser melting technology; In-situ quality detection is performed during the printing process, and the process parameters are adjusted in real time; S4. When the interface transition area of different materials is printed, the integrated formation of the multifunctional gradient material is realized by material alternative deposition; S5. After printing is completed, gradient heat treatment of segmented temperature control, surface treatment and performance detection are implemented.

5. The 3D printing method of the lightweight cross-scale dual cryogenic injector according to claim 4, wherein: ​ ​ The three-dimensional model comprises three layers of functional areas from outside to inside, namely an external shell area (P1), a sealing connection area (P2), and an internal flow passage area (P3), the external shell area (P1) is further divided into an inlet area (P11), a main load-bearing frame area (P12), and a nozzle area (P13), the inlet area (P11) is located at the positions of the first injection port (1) and the second injection port (2), the main load-bearing frame area (P12) is located at the positions of the upper liquid collecting disc (3), the connecting pipeline (4), and the lower liquid collector (5), and the nozzle area (P13) is located at the position of the nozzle (6). The core scale range of the macrostructure layer is 0.1 mm-10 mm, including the inlet area (P11), the main load-bearing frame area (P12), and the sealing connection area (P2), and the core scale range of the microfeature layer is 1 µm-100 µm, including the internal flow passage area (P3) and the nozzle area (P13).

6. The 3D printing method of the lightweight cross-scale dual-cryogenic injector according to claim 5, characterized in that: The first process parameter combination comprises a laser power of 300-400 W, a light spot diameter of 80-100 µm, a layer thickness of 40-60 µm, and a scanning speed of 800-1200 mm / s; The second process parameter combination comprises a laser power of 70-150 W, a light spot diameter of 20-40 µm, a layer thickness of 10-25 µm, and a scanning speed of 400-600 mm / s.

7. The 3D printing method of the lightweight cross-scale dual-cryogenic injector according to claim 6, characterized in that: The macrostructure layer has a thickness of 40-60 µm, and the microfeature layer has a thickness of 10-25 µm; The optimal laser scanning path planning comprises a long vector chessboard partition strategy for the macrostructure layer and a contour biasing and short vector filling strategy for the microfeature layer.

8. The 3D printing method of the lightweight cross-scale dual-cryogenic injector according to claim 7, characterized in that: The method for integrally forming the multifunctional gradient material is: When the printing interface transitions from one functional area to another functional area, in the transition area, the laser power is gradually adjusted from the typical value of the initial material to the typical value of the target material in a gradient adjustment method, and the scanning speed is adjusted synchronously, a metallurgical bonding transition zone is formed at the interface, and the microstructure of the metallurgical bonding transition zone presents a continuous composition gradient change.

9. The 3D printing method of the lightweight cross-scale dual-cryogenic injector according to claim 8, characterized in that: The in-situ quality detection comprises real-time monitoring of the printing state, and when an abnormal molten pool temperature is identified, the laser power and the scanning speed are adjusted, and when a geometric defect is identified, the powder feeding amount is adaptively adjusted or local area secondary finishing is started.

10. The 3D printing method of the lightweight cross-scale dual-cryogenic injector according to claim 9, characterized in that: The gradient heat treatment is to set multiple segmented temperature control zones, and respectively perform differential aging treatment on the nozzle area (P13), the inlet area (P11), the internal flow passage area (P3), the main bearing frame area (P12) and the sealing connection area (P2); The surface treatment includes surface polishing of the internal flow passage area (P3) and surface high-temperature-resistant and corrosion-resistant coating treatment of the nozzle area (P13).

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