An integrally molded double-layer nozzle structure suitable for supercritical fluids

Abstract

This invention discloses an integrally molded double-layer nozzle structure suitable for supercritical fluids, comprising: an attitude and orbit control nozzle and an exhaust outer pipe; the attitude and orbit control nozzle is used to realize the flow of supercritical medium, which is accelerated through the throat of the attitude and orbit control nozzle and then ejected to obtain thrust; the exhaust outer pipe is integrated on the outside of the attitude and orbit control inner pipe and is used to realize the flow of exhaust medium. This invention provides attitude and orbit control thrust through the inner pipe and realizes the function of medium discharge through the outer pipe, which can reduce independent components, improve the propulsion efficiency and mission adaptability of the spacecraft, and achieve a generational upgrade of aerospace technology.

Description

Technical Field

[0001] This invention relates to an integrally molded double-layer nozzle structure suitable for supercritical fluids, belonging to the field of aircraft nozzle technology. Background Technology

[0002] The aircraft nozzle is the core actuator for attitude control, providing rapid and precise attitude adjustment capabilities through thrust regulation and vector control. In propulsion systems, supercritical media, due to their low viscosity, high density, and high diffusivity, allow for smoother energy release when the fluid expands through the nozzle, possessing the potential for efficient thrust conversion. Existing attitude and trajectory control nozzle designs only consider thrust realization without coupling with the system design, resulting in low structural design efficiency. Therefore, research on attitude and trajectory control nozzles suitable for high-pressure supercritical media is needed. Combining this with system characteristics, and while meeting thrust requirements, the design should also realize other functions such as system pre-cooling and media discharge. This will support the design and development of attitude and trajectory control thrust systems for relevant models in emerging fields, and through high integration with the system, effectively improve the structural efficiency of the product, possessing significant engineering application value. Summary of the Invention

[0003] The purpose of this invention is to overcome the aforementioned shortcomings and provide an integrally molded double-layer nozzle structure suitable for supercritical fluids. Through system coupling design, it solves the technical problem of low design efficiency in existing attitude and orbit control nozzle structures for high-pressure supercritical media. The inner tube of this invention provides attitude and orbit control thrust, while the outer tube performs the function of media discharge. This reduces independent components, improves the propulsion efficiency and mission adaptability of spacecraft, and achieves a generational upgrade in aerospace technology.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0005] This invention relates to an integrally molded double-layer nozzle structure suitable for supercritical media. The double-layer nozzle adopts an integrated design of inner and outer tubes. The inner tube provides attitude and trajectory control thrust, while the outer tube performs the function of media discharge. Through surface design, supercritical carbon dioxide generates momentum changes on the inner surface of the inner tube, forming thrust. The exhaust outer tube is fitted onto the outside of the attitude and trajectory control inner tube, integrally molded with the inner tube, and is used for media discharge, simultaneously achieving cooling of the main nozzle structure and ensuring the stability of the supercritical media flow state within the attitude and trajectory control inner tube.

[0006] An integrally molded double-layer nozzle structure suitable for supercritical fluids includes: an attitude control nozzle and an exhaust pipe;

[0007] The attitude control nozzle is used to realize the flow of supercritical media. The supercritical media is accelerated through the throat of the attitude control nozzle and then ejected to obtain thrust.

[0008] The exhaust pipe is integrated on the outside of the attitude control inner pipe to facilitate the flow of exhaust medium. In operation, the exhaust medium can be cold air, which cools the attitude control nozzle. In non-operational operation, the exhaust medium can be waste gas.

[0009] Furthermore, the throat area A of the attitude control nozzle t Determine according to the following formula:

[0010]

[0011] Among them, C F ρ is the thrust coefficient; F is the thrust; p1 is the inlet pressure; p2 is the outlet pressure; p3 is the ambient pressure; k c A1 represents the specific heat ratio of the supercritical medium; A2 represents the outlet area.

[0012] Furthermore, the expansion diameter of the expansion section at the exit of the attitude control nozzle is 0.3–0.5D. t The diameter of the inlet contraction section is 1-2D. t ;D t The diameter of the throat of the attitude control nozzle;

[0013] The attitude control nozzle expansion cone angle is 24–36°.

[0014] Furthermore, the inner diameter of the exhaust pipe inlet is determined according to the following formula:

[0015]

[0016] Among them, D wr Q is the inner diameter of the exhaust pipe inlet; m T0 is the mass flow rate of the exhaust medium; C is the inlet temperature of the exhaust pipe; p is the flow coefficient; T0 is the mass flow rate of the exhaust medium; T0 is the inlet temperature of the exhaust pipe; C is the flow coefficient; p is the mass flow rate of the exhaust medium ... 01 c is the inlet pressure of the exhaust pipe; m These are the physical properties of the exhaust medium.

[0017] Furthermore, c m Calculate using the following formula:

[0018]

[0019] Where m is the molecular weight of the exhaust medium; p 02 k is the outlet pressure of the exhaust pipe. p The specific heat ratio of the exhaust medium;

[0020]

[0021] Among them, c p is the specific heat capacity at constant pressure; R is the universal gas constant.

[0022] Furthermore, the angle between the inlet of the attitude control nozzle and the inlet of the exhaust pipe is 90°, and the outlet end of the exhaust pipe turns in the same direction as the outlet of the attitude control nozzle; the outlet of the exhaust pipe is fitted outside the outlet of the attitude control nozzle.

[0023] Furthermore, the outer diameter D of the attitude control nozzle outlet n and exhaust pipe outlet inner diameter D w Satisfy the following formula:

[0024]

[0025] Among them, D wr This refers to the inner diameter of the exhaust pipe inlet.

[0026] Furthermore, four symmetrical support legs are installed at the end of the exhaust pipe outlet to achieve local reinforcement of the structure; the two ends of each support leg are respectively connected to the inner wall of the exhaust pipe and the outer wall of the attitude control nozzle, and the direction of the support leg is along the radial direction of the exhaust pipe.

[0027] Furthermore, the supercritical medium is supercritical carbon dioxide.

[0028] Furthermore, the dual-layer nozzle structure is integrally formed using additive manufacturing technology;

[0029] During molding, the overhang angle is kept ≤45° at positions where the support is difficult to remove, thus achieving self-support; the surface roughness of the attitude control nozzle is kept ≤Ra6.3 by electrochemical polishing.

[0030] Compared with the prior art, the present invention has at least one of the following advantages:

[0031] (1) This invention addresses the system’s emission requirements by coupling the attitude and orbit control thrust system with the exhaust system and adopting an integrated solution of exhaust outer pipe fitted with attitude and orbit control inner pipe, which reduces independent components and improves structural design efficiency.

[0032] (2) Based on the physical properties and thrust index of supercritical medium under rated working conditions, this invention completes the nozzle attitude and trajectory control surface design and realizes efficient thrust conversion;

[0033] (3) The exhaust medium temperature is low. The delivery of the low-temperature exhaust medium in the outer pipe can achieve the cooling of the main structure of the nozzle, thereby eliminating the influence of temperature change on the flow state of the supercritical medium and ensuring the stability of the attitude and orbit control nozzle thrust.

[0034] (4) The main structure of the nozzle adopts an additive manufacturing integrated molding process to achieve near-net-shape forming of the double-layer sleeve structure. The overhang angle is guaranteed to be ≤45° in the positions where the support is not easy to remove, so as to achieve self-support. At the same time, the surface roughness of the inner flow channel is guaranteed to be ≤Ra6.3 through electrochemical polishing, and the process maturity is high. Attached Figure Description

[0035] Figure 1 This is a front view of the integrally molded double-layer nozzle structure applicable to supercritical media according to the present invention;

[0036] Figure 2 This is a side view of the integrally molded double-layer nozzle structure applicable to supercritical media according to the present invention;

[0037] Figure 3 This is a cross-sectional view of the integrally molded double-layer nozzle structure applicable to supercritical media according to the present invention. Detailed Implementation

[0038] The features and advantages of the present invention will become clearer and more apparent from the following detailed description.

[0039] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0040] This invention addresses the lightweight and high-efficiency requirements of the aerospace field by coupling the attitude and orbit control thrust system with the exhaust system through functional reuse and structural optimization, thereby improving structural design efficiency. This invention proposes a single-piece, double-layer nozzle structure that simultaneously provides attitude control and media discharge functions, thus reducing independent components, improving the propulsion efficiency and mission adaptability of the spacecraft, and achieving a generational upgrade in aerospace technology.

[0041] The purpose of this invention is to couple the attitude control thrust system with the exhaust system, and to conduct integrated design, providing an integrally molded double-layer nozzle structure suitable for supercritical media. This reduces independent components and improves structural design efficiency. The medium inside the nozzle is a low-viscosity, high-density, and highly diffusive supercritical carbon dioxide medium, which has the potential for efficient thrust conversion. The exhaust pipe circulates the exhaust medium, achieving the integration of attitude control and exhaust. Simultaneously, the circulation of the low-temperature exhaust medium cools the main nozzle structure and solves the problem of thrust being affected by changes in the flow state of the supercritical medium nozzle due to temperature variations.

[0042] like Figure 1 This integrated, double-layer nozzle structure is suitable for supercritical media. The inner tube serves as the attitude control nozzle, connecting to the media delivery pipeline to facilitate the flow of supercritical carbon dioxide. The high-pressure medium is accelerated through the nozzle throat and ejected at high speed to generate thrust. The exhaust pipe is integrated on the outside of the inner tube, completing the discharge of the cryogenic medium while simultaneously cooling the main nozzle structure. This prevents changes in the properties of the supercritical medium within the attitude control inner tube, ensuring stable thrust.

[0043] 1) Determination of the geometric parameters of the inner surface of the attitude control nozzle:

[0044] Based on the system thrust index and inlet pressure, combined with equation (1) and the physical properties of the supercritical medium under rated operating conditions, the area A of the nozzle throat is determined. t :

[0045]

[0046] in,

[0047] C F —Thrust coefficient;

[0048] F—Thrust, N;

[0049] p1—Inlet pressure, MPa;

[0050] p2—Outlet pressure, MPa;

[0051] p3—Ambient pressure, MPa;

[0052] k c —Specific heat ratio of supercritical media, K;

[0053] A t —Throat area, mm 2 ;

[0054] A2—Export area, mm 2 .

[0055] Meanwhile, the diameter of the expansion segment at the export end is 0.4D. t The diameter of the inlet contraction section is 1.5D. t The expansion cone angle is generally taken as 24 to 36°, and the value needs to be compromised according to the specific purpose and flight trajectory.

[0056] in,

[0057] D t —Throat diameter, mm.

[0058] In addition, such as Figure 3 As shown, the inner diameter of the attitude control nozzle inlet is set to D. nr .

[0059] 2) Determination of exhaust pipe geometry parameters:

[0060] The inner diameter of the exhaust pipe inlet can be determined by the inlet pressure, medium flow rate and temperature, as shown in equation (2).

[0061]

[0062] in,

[0063] D wr —Exhaust pipe inlet inner diameter, mm;

[0064] Q m —Exhaust medium mass flow rate, g / s;

[0065] T0—Exhaust pipe inlet temperature, K;

[0066] C—Flow coefficient;

[0067] p 01 —Exhaust pipe inlet pressure, MPa;

[0068] c m —Physical properties of the exhaust medium.

[0069] Among them, c m Calculated using equation (3):

[0070]

[0071] in,

[0072] m—Molecular weight of the exhaust medium, g / mol;

[0073] k p —Specific heat ratio of the exhaust medium, K;

[0074] p 02 —Exhaust pipe outlet pressure, MPa.

[0075] in,

[0076]

[0077] in,

[0078] c p —Specific heat capacity at constant pressure, J / (Kg·K);

[0079] R—Universal gas constant, typically taken as 8314.3 J / (Kg·mol·K);

[0080] To avoid interference between the outer and inner pipe inlets, the angle between the exhaust outer pipe inlet 1 and the attitude control nozzle inlet 2 (inner pipe inlet) is designed to be 90°. The exhaust outer pipe outlet 3 is rotated in the same direction as the attitude control nozzle outlet 4 (inner pipe outlet), and is fitted on the outside of the inner pipe to solve the influence of the outer pipe medium discharge on the inner pipe thrust. The nozzle mounting panel 5 is located on the outside of the exhaust outer pipe outlet and is used to connect the double-layer nozzle structure to the outer wall of the propulsion system. To avoid throttling, the outer pipe must meet equation (5):

[0081]

[0082] in,

[0083] D n—Inner tube outer diameter, mm;

[0084] D w —Outer tube inner diameter, mm.

[0085] In addition, four symmetrical support legs 7 are installed at the outlet end of the outer tube to achieve local reinforcement of the structure and avoid yielding, such as Figure 2 As shown. The inner and outer tube wall thicknesses are given based on structural loads and strength calculations.

[0086] 3) Integrated molding process solution:

[0087] The main nozzle structure 6 employs an additive manufacturing process to achieve near-net-shape forming of the double-layer sleeve structure. Overhang angles of ≤45° are maintained at locations where supports are difficult to remove, ensuring self-support. Simultaneously, electrochemical polishing ensures the surface roughness of the inner flow channel is ≤Ra6.3.

[0088] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

[0089] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A one-piece molded double-layer nozzle structure suitable for supercritical fluids, characterized in that, include: Attitude control nozzle and exhaust manifold; The attitude control nozzle is used to realize the flow of supercritical media. The supercritical media is accelerated through the throat of the attitude control nozzle and then ejected to obtain thrust. The exhaust pipe is integrated on the outside of the attitude control nozzle to facilitate the flow of exhaust medium; Attitude and trajectory control nozzle throat area Determine according to the following formula: ； in, This is the thrust coefficient; F For thrust; For inlet pressure; To alleviate export pressure; Due to environmental pressures; The specific heat ratio of a supercritical medium; For export area; The expansion diameter of the exit expansion section of the attitude control nozzle is 0.3~0.5 mm. The diameter of the inlet contraction section is 1~2 mm. ; The diameter of the throat of the attitude control nozzle; The attitude control nozzle expansion cone angle is 24~36°; The inner diameter of the exhaust pipe inlet is determined according to the following formula: ; in, This refers to the inner diameter of the exhaust pipe inlet. This refers to the mass flow rate of the exhaust medium. This refers to the inlet temperature of the exhaust pipe. For flow coefficient; This refers to the inlet pressure of the exhaust pipe. These are the physical properties of the exhaust medium; Calculate using the following formula: ； in, The molecular weight of the exhaust medium; This refers to the outlet pressure of the exhaust pipe. The specific heat ratio of the exhaust medium; ； in, Specific heat capacity at constant pressure; This is the universal gas constant; The angle between the inlet of the attitude control nozzle and the inlet of the exhaust pipe is 90°, and the outlet end of the exhaust pipe turns in the same direction as the outlet of the attitude control nozzle; the outlet of the exhaust pipe is fitted outside the outlet of the attitude control nozzle.

2. The integrally molded double-layer nozzle structure suitable for supercritical fluids according to claim 1, characterized in that, Attitude and trajectory control nozzle outlet outer diameter and the inner diameter of the exhaust pipe outlet Satisfy the following formula: ； in, This refers to the inner diameter of the exhaust pipe inlet.

3. The integrally molded double-layer nozzle structure suitable for supercritical fluids according to claim 1, characterized in that, Four symmetrical support legs are installed at the end of the exhaust pipe outlet to achieve local reinforcement of the structure; the two ends of each support leg are connected to the inner wall of the exhaust pipe and the outer wall of the attitude control nozzle, respectively, and the direction of the support leg is along the radial direction of the exhaust pipe.

4. The integrally molded double-layer nozzle structure suitable for supercritical fluids according to claim 1, characterized in that, The supercritical medium is supercritical carbon dioxide.

5. The integrally molded double-layer nozzle structure suitable for supercritical fluids according to claim 1, characterized in that, The dual-layer nozzle structure is integrally formed using additive manufacturing technology; During molding, the overhang angle is kept ≤45° at positions where the support is difficult to remove, thus achieving self-support; the surface roughness of the attitude control nozzle is kept ≤Ra6.3 by electrochemical polishing.

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