Method for optimizing the design of an integrated structure of an ion thruster anode assembly based on additive manufacturing

Abstract

The application relates to the technical field of space electric propulsion, and particularly discloses an ion thruster anode assembly integrated structure design optimization method based on additive manufacturing, which comprises the following steps: determining the external size of a discharge chamber gas distribution ring in combination with input parameters of an ion thruster discharge chamber; calculating the circumferential pressure distribution of the gas distribution ring; completing the design of the number of apertures and the size of the gradually-changing apertures in combination with the pressure distribution and aperture diameter matching; designing a bidirectional spiral pressurizing flow channel; carrying out simulation analysis on the gas uniformity in combination with CFD; and finally, carrying out integrated modeling design and forming processing on the pressure gradient compensation type ion thruster anode and the gas distribution ring based on additive manufacturing. The application aims at the core requirement of the circumferential gas supply uniformity of the ion thruster discharge chamber, realizes the balanced distribution of the gas through flow channel pressure compensation and gradually-changing aperture reverse adjustment, overcomes the problem of the circumferential gas supply unevenness caused by the flow channel pressure gradient of the traditional gas distribution ring, and realizes the uniform gas supply in the ion thruster discharge chamber.

Description

Technical Field

[0001] This invention relates to the field of aerospace electric propulsion technology, specifically to a method for optimizing the integrated structure design of an ion thruster anode assembly based on additive manufacturing. Background Technology

[0002] Electric propulsion, with its advantages of high specific impulse and long lifespan, has become a hallmark of advanced satellite platforms, providing power for spacecraft. In the field of interplanetary deep space exploration, electric thrusters have received widespread attention and engineering applications from various countries. Ion thrusters generate thrust by ionizing gaseous working fluids into plasma and accelerating the extraction of ions.

[0003] The existing ion thruster gas distribution ring has a high pressure at the near end and a low pressure at the far end due to the position of the inlet pipe, resulting in different intake volumes. The pressure concentration at the inlet pipe end leads to the difference in flow rate between the near and far ends, causing uneven thruster discharge and poor uniformity of ion beam current density. This exacerbates sputtering and etching of the ion thruster, restricting the stability of thruster discharge and the extension of its lifespan.

[0004] Some designs use uniformly distributed openings of equal or simple linearly varying orifices, without considering the dynamic pressure attenuation law within the flow channel. Furthermore, due to limitations in manufacturing processes, traditional machining cannot achieve the integrated molding and manufacturing of micron-level varying orifices and complex internal flow channels.

[0005] Therefore, an integrated structure and design method for the anode assembly of an ion thruster based on additive manufacturing is proposed to overcome the problem of uneven circumferential gas supply caused by the pressure gradient in the flow channel of the traditional gas distribution ring. At the same time, the integrated design and manufacturing of the anode, complex internal flow channel, and gradient hole gas distribution ring are realized based on additive manufacturing. Summary of the Invention

[0006] The purpose of this invention is to provide an integrated structural design optimization method for the anode assembly of an ion thruster based on additive manufacturing. Addressing the core requirement of uniform circumferential gas supply in the discharge chamber of the ion thruster, this invention achieves balanced gas distribution through flow channel pressure compensation and reverse adjustment of the gradient orifice, overcoming the problem of uneven circumferential gas supply caused by the flow channel pressure gradient in traditional gas distribution rings. At the same time, based on additive manufacturing, the integrated design and manufacturing of the anode, complex internal flow channel, and gradient orifice gas distribution ring are realized, ultimately achieving uniform gas supply in the discharge chamber of the ion thruster.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] The method for optimizing the integrated structure design of the anode assembly of an ion thruster based on additive manufacturing includes the following steps:

[0009] Step S1: Determine the external dimensions of the gas distribution ring of the discharge chamber based on the structure, dimensions, gas supply method, and working fluid input parameters of the ion thruster discharge chamber;

[0010] Step S2: Calculate the circumferential pressure distribution of the gas distribution ring; a one-dimensional annular flow channel pressure attenuation model is used to model the circumferential pressure field of the gas distribution ring's annular track. The pressure distribution is as follows:

[0011] ;

[0012] Here, P1 is the pressure at the inlet where the inlet pipe connects to the gas distribution ring, D1 is the annular diameter of the gas distribution ring, h is the diameter of the gas distribution ring flow channel, K is the Knudsen number, μ is the gas dynamic viscosity, and Q is the flow rate at the outlet of the gas distribution ring. Based on the gas flow characteristics of the ion thruster under vacuum conditions, the gas flow is in the slip flow region. The flow rate at the outlet of the gas distribution ring of the ion thruster is calculated using the modified Poiseuille equation.

[0013] ;

[0014] Here, d is the outlet diameter, P i It is the pressure upstream of the orifice, P d It is the pressure in the discharge chamber of the ion thruster. L is the effective length of the gas distribution ring outlet channel.

[0015] Step S3: Combine pressure distribution and gas distribution ring orifice diameter matching to complete the design of orifice quantity and gradient orifice size; in order to achieve circumferential flow balance of the gas distribution ring, the pressure compensation gradient outlet orifice diameter distribution of the gas distribution ring is obtained by solving the flow equations simultaneously:

[0016] ;

[0017] ;

[0018] Q1 is the total input flow rate, N is the number of pressure-compensated gradient outlet holes in the gas distribution ring, Q avg This represents the average flow rate of a single air outlet.

[0019] Simplified to:

[0020] ;

[0021] d b Design aperture as a reference, d i Let be the diameter of the i-th air outlet.

[0022] Step S4: Design of a bidirectional spiral booster channel; Two air inlets are designed. The spiral booster channel connected to inlet pipe one is integrated with the anode wall of the ion thruster, spiraling clockwise and connecting diagonally to the gas distribution ring. The spiral booster channel connected to inlet pipe two is also integrated with the anode wall of the ion thruster, spiraling clockwise and connecting diagonally to the gas distribution ring. Pressure attenuation is compensated by shrinking the cross-sectional area of ​​the channel. The cross-sectional area of ​​the spiral booster channel shrinks exponentially, with the cross-sectional area A(y) at a distance y along the channel direction as follows:

[0023] ;

[0024] A0 is the initial cross-sectional area of ​​the flow channel, and the shrinkage coefficient k is:

[0025] ;

[0026] P ref This refers to the pressure at the air inlet.

[0027] Step S5: Combine CFD gas uniformity simulation analysis; combine CFD with simulation analysis to iteratively verify and optimize the integrated structure of the pressure gradient compensated ion thruster anode and gas distribution ring designed according to the above steps. Step S6: Based on additive manufacturing, model and design the integrated structure of the pressure gradient compensated ion thruster anode and gas distribution ring and perform molding processing.

[0028] As a further aspect of the present invention: In step S3, the design of the number of orifices and the size of the gradual orifice is completed by combining the pressure distribution and the orifice diameter matching of the gas distribution ring. The orifice diameter is small at the near end and large at the far end, reaching the maximum at the farthest end from the air inlet. Triangular micro-rib structures are set in the flow channel inside the gas distribution ring. The flow channel is divided by the triangular micro-ribs to form a periodic velocity gradient, induce local vortices, and enhance gas mixing.

[0029] As a further aspect of the present invention: Step S6 involves the integrated modeling and molding of the anode and gas distribution ring of the pressure gradient compensated ion thruster based on additive manufacturing. The gas distribution ring outlet is designed to be conical, with a larger outer diameter and a smaller inner diameter, to prevent printing powder residue during additive manufacturing and reduce the risk of foreign matter inside the pipeline.

[0030] The beneficial effects of this invention are as follows: This invention addresses the core problems of existing ion thruster gas distribution rings, where the pressure is high at the proximal end and low at the distal end due to the location of the inlet pipe, resulting in different gas intake volumes. The concentrated pressure at the inlet pipe end leads to flow rate differences between the proximal and distal ends, causing uneven thruster discharge, poor ion beam current density uniformity, and aggravated sputtering etching in the ion thruster. By achieving balanced gas distribution through flow channel pressure compensation and reverse adjustment of the gradient aperture, this invention overcomes the circumferential gas supply unevenness caused by the flow channel pressure gradient in traditional gas distribution rings. Furthermore, based on additive manufacturing, the anode, complex internal flow channel, and gradient aperture gas distribution ring are designed and manufactured as a single unit, ultimately achieving uniform gas supply within the ion thruster discharge chamber. Attached Figure Description

[0031] The invention will now be further described with reference to the accompanying drawings.

[0032] Figure 1 This is a flowchart illustrating the integrated structure design of the ion thruster anode assembly in this invention.

[0033] Figure 2 This is a schematic diagram of the integrated structure of the ion thruster anode assembly in this invention;

[0034] Figure 3 This is a half-sectional schematic diagram of the integrated structure of the ion thruster anode assembly in this invention;

[0035] Figure 4 This is a cross-sectional view of the integrated structure of the ion thruster anode assembly in this invention;

[0036] Figure 5 This is a schematic diagram of the gas distribution ring in this invention;

[0037] Figure 6 This is a partially enlarged schematic diagram of the gas distribution ring outlet in this invention;

[0038] Figure 7 This is a beam density distribution diagram after the implementation of the conventional uniformly distributed perforated gas distribution ring with equal aperture in this invention;

[0039] Figure 8 This is a beam density distribution diagram after implementation in this invention.

[0040] In the diagram: 1. Anode; 2. Gas distribution ring; 3. Spiral booster channel; 4-1. Inlet pipe one; 4-2. Inlet pipe two; 5. Conical outlet; 6. Triangular micro ribs. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0042] Please see Figures 1-8 As shown, the present invention is a design optimization method for an integrated structure of an ion thruster anode assembly based on additive manufacturing. The pressure gradient compensation type ion thruster anode assembly structure based on additive manufacturing mainly includes: anode 1, gas distribution ring 2, spiral pressurization channel 3, inlet pipe 1 4-1, and inlet pipe 2 4-2.

[0043] like Figure 1 As shown, the integrated structure and design method of the ion thruster anode assembly based on additive manufacturing includes the following steps:

[0044] Step S1: Determine the external dimensions of the gas distribution ring of the discharge chamber based on the structure, dimensions, gas supply method, and working fluid input parameters of the ion thruster discharge chamber;

[0045] Step S2: Calculate the circumferential pressure distribution of the gas distribution ring; use a one-dimensional annular flow channel pressure attenuation model to model the circumferential pressure field of the gas distribution ring's annular track.

[0046] The pressure distribution is as follows:

[0047] ;

[0048] Here, P1 is the pressure at the inlet where the inlet pipe connects to the gas distribution ring, D1 is the annular diameter of the gas distribution ring, h is the diameter of the gas distribution ring flow channel, K is the Knudsen number, μ is the gas dynamic viscosity, and Q is the flow rate at the outlet of the gas distribution ring.

[0049] Based on the gas flow characteristics of the ion thruster in a vacuum environment, the gas flow is in the slip flow region. The modified Poisson's equation is used to calculate the flow rate at the outlet of the gas distribution ring of the ion thruster.

[0050] ;

[0051] Here, d is the outlet diameter, P i It is the pressure upstream of the orifice, P d It is the pressure in the discharge chamber of the ion thruster. L is the effective length of the gas distribution ring outlet channel.

[0052] Step S3: Combine pressure distribution and gas distribution ring orifice diameter matching to complete the design of orifice quantity and gradient orifice size; in order to achieve circumferential flow balance of the gas distribution ring, the pressure compensation gradient outlet orifice diameter distribution of the gas distribution ring is obtained by solving the flow equations simultaneously:

[0053] ;

[0054] ;

[0055] Q1 is the total input flow rate, N is the number of pressure-compensated gradient outlet holes in the gas distribution ring, Q avg This represents the average flow rate of a single air outlet.

[0056] Simplified to:

[0057] ;

[0058] d b Design aperture as a reference, d i Let be the diameter of the i-th air outlet.

[0059] Step S4: Design of bidirectional spiral booster channel; Design two air inlets. The spiral booster channel 3, which is connected to the inlet pipe 1 4-1, is designed to spiral up clockwise along the anode wall of the ion thruster and connects to the gas distribution ring at the diagonal. The spiral booster channel, which is connected to the inlet pipe 2 4-2, is designed to spiral up clockwise along the anode wall of the ion thruster and connects to the gas distribution ring at the diagonal.

[0060] Pressure attenuation is compensated by shrinking the cross-sectional area of ​​the flow channel. The cross-sectional area of ​​the spiral pressurizing flow channel shrinks exponentially, and the cross-sectional area A(y) at a distance y along the flow channel direction is:

[0061] ;

[0062] A0 is the initial cross-sectional area of ​​the flow channel, and the shrinkage coefficient k is:

[0063] ;

[0064] P ref This refers to the pressure at the air inlet.

[0065] Step S5: Combine CFD gas uniformity simulation analysis; combine CFD to perform simulation analysis, iterative verification and optimization of the integrated structure of the pressure gradient compensated ion thruster anode and gas distribution ring designed according to the above steps;

[0066] Step S6: Integrated modeling and molding of the anode and gas distribution ring of the pressure gradient compensated ion thruster based on additive manufacturing.

[0067] Step S3 combines pressure distribution and gas distribution ring orifice diameter matching to complete the design of the number of orifices and the size of the gradually changing orifice diameter, in which the gas distribution ring ( Figure 5 As shown, the locations connected to the spiral booster channel are A and C, respectively. When designing the gradual aperture size, start from A and C, and design gradually from both sides according to Formula 3. The aperture is small at the near end and large at the far end, reaching its maximum at B and D, which are the two points furthest from the air inlet.

[0068] Figure 6 The diagram shows a partial enlarged view of the gas outlet of the gas distribution ring. Triangular micro-rib structures 6 are set in the flow channel inside the gas distribution ring. The flow channel is divided by the triangular micro-ribs to form a periodic velocity gradient, induce local vortices, and enhance gas mixing.

[0069] Step S6: Integrated modeling and molding of the anode and gas distribution ring of the pressure gradient compensated ion thruster based on additive manufacturing. The gas distribution ring outlet 5 is designed as a cone shape, larger on the outside and smaller on the inside, to prevent printing powder residue during additive manufacturing and reduce the risk of foreign matter inside the pipeline.

[0070] Example: According to the additive manufacturing-based integrated structure and design method of the anode assembly of an ion thruster provided by the present invention, with the annular diameter D1 of the gas distribution ring being 340 mm, the reference design aperture d b With Xe as the initial parameters (0.5mm, intake pipe diameter 2mm, air supply volume 100sccm), and optimized according to the method of this patent, the number of holes N is 48, and the initial cross-sectional area A0 of the spiral flow channel is 1.8mm². 2 The shrinkage coefficient k is 0.015~0.025mm. －1 The triangular micro-ribs 6 have a height of 0.12 mm, a spacing of 0.48 mm, and an aperture range from 0.505 mm (near end) to 0.540 mm (far end). The effectiveness of this patent was evaluated by measuring the beam density distribution extracted from the ion thruster; beam uniformity was improved by 27%. Figure 7 Beam density distribution diagram after implementation of a traditional uniformly distributed gas distribution ring with equal aperture. Figure 8 This is a beam density distribution diagram after the implementation of the present invention.

[0071] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

[0072] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A method for optimizing the integrated structure design of an ion thruster anode assembly based on additive manufacturing, characterized in that, Includes the following steps: Step S1: Determine the external dimensions of the gas distribution ring in the discharge chamber based on the input parameters of the ion thruster discharge chamber; Step S2: A one-dimensional annular flow channel pressure decay model is used to model the circumferential pressure field of the gas distribution ring annular track and calculate the circumferential pressure distribution of the gas distribution ring. At the same time, based on the characteristics of the gas flow in the slip flow region under the vacuum environment of the ion thruster, the modified Poisson's equation is used to calculate the flow rate at the gas distribution ring outlet. Step S3: Combine pressure distribution and gas distribution ring orifice diameter matching to complete the design of orifice number and gradient orifice size; Step S4: Design a bidirectional spiral booster channel with two air inlets. The two spiral booster channels connected to each other are designed as an integral part of the anode along the anode wall of the ion thruster, spiraling upwards in a clockwise direction and connecting to the gas distribution ring at the opposite corner. The cross-sectional area of ​​the spiral booster channel shrinks exponentially to compensate for the pressure decay. Step S5: Combine CFD to perform gas uniformity simulation analysis on the integrated structure of the anode and gas distribution ring of the pressure gradient compensated ion thruster, and complete the structural optimization through iterative verification; Step S6: Perform integrated modeling and design of the optimized pressure gradient compensated ion thruster anode and gas distribution ring, and complete the forming process based on additive manufacturing technology.

2. The method for optimizing the integrated structure design of the anode assembly of an ion thruster based on additive manufacturing according to claim 1, characterized in that, In step S2, the calculation model for the circumferential pressure distribution of the gas distribution ring is as follows: ； Where P1 is the pressure at the inlet of the gas distribution ring at the connection between the inlet pipe and the gas distribution ring, D1 is the annular diameter of the gas distribution ring, h is the diameter of the gas distribution ring flow channel, K is the Knudsen number, μ is the gas dynamic viscosity, and Q is the flow rate at the outlet of the gas distribution ring. The corrected Poiseuille equation is: ； Where d is the outlet diameter, P i It is the pressure upstream of the orifice, P d It is the pressure in the discharge chamber of the ion thruster. L is the effective length of the gas distribution ring outlet channel.

3. The method for optimizing the integrated structure design of the anode assembly of an ion thruster based on additive manufacturing according to claim 2, characterized in that, Step S3 specifically includes: The pressure-compensated, gradually varying orifice diameter distribution of the gas distribution ring is obtained by simultaneously solving the flow equations: ； ； Where Q1 is the total input flow rate, N is the number of pressure-compensated gradient outlet holes in the gas distribution ring, and Q avg The average flow rate of a single air outlet; Simplified, we get: ； Where, d b Design aperture as a reference, d i Let be the diameter of the i-th air outlet.

4. The method for optimizing the integrated structure design of the anode assembly of an ion thruster based on additive manufacturing according to claim 3, characterized in that, Step S4 specifically includes: Pressure attenuation is compensated by shrinking the cross-sectional area of ​​the flow channel. The cross-sectional area of ​​the spiral pressurizing flow channel shrinks exponentially, and the cross-sectional area A(y) at a distance y along the flow channel direction is: ； Where A0 is the initial cross-sectional area of ​​the flow channel, and k is the shrinkage coefficient; The shrinkage coefficient k is calculated as follows: ； Among them, P ref This refers to the pressure at the air inlet.

5. The method for optimizing the integrated structure design of the anode assembly of an ion thruster based on additive manufacturing according to claim 1, characterized in that, In step S3, the design of the number of orifices and the size of the gradually changing orifices is completed by combining the pressure distribution and the orifice diameter matching of the gas distribution ring. The orifice diameter gradually increases from the near end to the far end, and reaches its maximum at the farthest end from the air inlet.

6. The method for optimizing the integrated structure design of the anode assembly of an ion thruster based on additive manufacturing according to claim 5, characterized in that, In step S3, a triangular micro-rib structure is set in the flow channel inside the gas distribution ring. The triangular micro-ribs divide the flow channel to form a periodic velocity gradient, induce local vortices, and enhance gas mixing.

7. The method for optimizing the integrated structure design of the anode assembly of an ion thruster based on additive manufacturing according to claim 1, characterized in that, In step S6, the anode and gas distribution ring of the pressure gradient compensated ion thruster based on additive manufacturing are integrated in modeling and forming. The gas distribution ring outlet is set to be conical, gradually decreasing in size from the outside to the inside.

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