Tesla valve structure-imitated micro-flow controller and preparation method thereof

Abstract

According to the Tesla valve structure-imitated micro-flow controller and the preparation method thereof, improvement design is carried out on the basis of an existing Tesla valve structure, the pipe wall of a first branch straight pipe section is designed to be of an arc-shaped structure, the area is increased by 20%-30%, a sawtooth-shaped structure is arranged on the pipe wall, a tiny cavity is additionally formed in a second branch straight pipe section, and the area of the first branch straight pipe section is increased by 20%-30%; the diameter of the structure of the shunting section is modified to be gradually increased, so that the cross sectional area of the shunting section is expanded by 25%-30%, the inner diameter of the branch annular section is reduced, the outer diameter of the branch annular section is expanded, the area of the expanded branch annular section is increased by 25%-35%, and the length of the outlet section is prolonged to be 30%-40% of the original length. The micro-flow controller with the imitated Tesla valve structure prepared by the invention can effectively guide fluid to flow, reduce accumulation of micro-particles in a micro-channel and enhance the impurity particle embolism resistance of a system, so that the stability and reliability of the whole system are improved.

Description

Technical Field

[0001] This invention relates to the field of flow control design, specifically a Tesla valve-inspired microflow controller and its fabrication method. Background Technology

[0002] Hall effect propulsion is a typical spacecraft electric propulsion system, possessing advantages such as high thrust-to-power ratio, high thrust density, high specific impulse, and system simplicity and reliability. Hall thrusters have extremely stringent requirements for propellant flow control, requiring high inlet pressure and very low outlet flow. Reducing the outlet pressure to 5–10 kPa while maintaining an outlet flow rate of 0.1–20 mg / s is crucial for the stable operation of Hall thrusters. However, flow control within the microchannel is frequently affected by microparticles and other impurities. The accumulation of these impurities in the microchannel can lead to flow resistance or even embolism, severely impacting the system's stability and reliability. Particularly in Hall thrusters, where xenon is typically used as the propellant, the precision of its flow control is critical to propulsion efficiency and spacecraft orbit maintenance.

[0003] The microchannels used in flow controllers of commonly used Hall thrusters are single-inlet / single-outlet type. Once foreign matter (microparticles and other impurities) accumulates in the microchannels, it can lead to flow resistance or even blockage. For example, commonly used metal capillary microchannels, due to their small inner diameter and single-inlet / single-outlet structure, are easily clogged by impurities. Therefore, frequent capillary replacements are necessary to ensure normal operation of the equipment. However, capillary tubes are relatively expensive, increasing the cost of analyzing metal content. Summary of the Invention

[0004] To address the problems of existing technologies, this invention provides a Tesla valve-inspired microflow controller and its fabrication method, which can effectively guide fluid flow, reduce the accumulation of microparticles in microchannels, enhance the system's resistance to impurity particle embolism, and thus improve the stability and reliability of the entire system.

[0005] This invention provides a Tesla valve-inspired microflow controller, comprising a Tesla valve array structure fixed in a sealed cylinder. The Tesla valve array structure consists of several Tesla valves evenly spaced on a circumference. Each Tesla valve includes an inlet section, a branch section, a branch straight pipe section, a branch annular section, and an outlet section. The branch straight pipe section includes a first branch straight pipe section and a second branch straight pipe section. The inlet of the branch annular section connects to the outlet of the first branch straight pipe section, and the outlet of the branch annular section merges with the outlet of the second branch straight pipe section and connects to the outlet section. The wall of the first branch straight pipe section has an arc-shaped structure with serrated edges; the second branch straight pipe section has micro-cavities.

[0006] Further improvements include a gradual increase in the diameter of the branching section from the inlet section to the branch straight pipe section.

[0007] This invention also provides a method for preparing a Tesla-valve-inspired microflow controller, comprising the following steps: 1) Model the existing Tesla valve structure and adjust the model parameters as follows: 1.1) Adjust the parameters of the branch section so that the diameter of the branch section gradually increases from the inlet section to the branch straight pipe section. After expansion, the cross-sectional area of ​​the flow channel of the branch section is increased by 25% to 30% compared with the cross-sectional area of ​​the original corresponding area. 1.2) Adjust the parameters of the first branch straight pipe section, change the straight pipe of the first branch straight pipe section to an arc pipe to expand the area, and increase the area of ​​the first branch straight pipe section by 20%~30%. At the same time, design a sawtooth structure on the pipe wall. 1.3) Adjust the parameters of the second branch straight pipe section and add a small cavity on the inner wall of the second branch straight pipe section; 1.4) Adjust the parameters of the branch annular segment, reduce the inner diameter and expand the outer diameter. The inner diameter is reduced by 3% to 5% compared to before expansion, and the outer diameter is increased by 2% to 3% compared to before expansion. After expansion, the area of ​​the annular segment increases by 25% to 35%. 1.5) Adjust the parameters of the outlet section and extend the flow channel axially along the axis of the main flow channel, with an expansion amount of 30% to 40% of the original length of the outlet section; 2) Select materials and use 3D printing technology to construct pipes layer by layer based on the CAD model; 3) Set the printing parameters, fabricate a single Tesla valve structure, and perform surface treatment; 4) Multiple Tesla valve structure arrays are combined and fixed in a sealed cylinder to form a Tesla valve-like microflow controller.

[0008] Further improvements were made by selecting Ti-6Al-4V titanium alloy powder as the material in step 2), with a particle size of 15-45μm, and choosing selective laser melting (SLM) technology as the 3D printing technology.

[0009] Further improvements were made, with the printing parameters in step 3) being: laser power 250-300W, scanning speed 500-1000mm / s, layer thickness 0.05-0.1mm, and scanning spacing 0.1mm.

[0010] Further improvements, the surface treatment process in step 3) specifically involves: first, mechanically removing the support structure, then using sandblasting to achieve a surface roughness of less than Ra1.6μm, followed by chemical polishing.

[0011] The beneficial effects of this invention are as follows: 1. The Tesla-inspired valve-structured microflow controller utilizes its unique multi-wing structure and multi-deceleration channel design to effectively guide fluid flow and reduce the accumulation of microparticles in the microchannels. This design enhances the system's resistance to impurity particle embolism, thereby improving the overall system stability and reliability.

[0012] 2. The Tesla-inspired valve structure, while ensuring outlet pressure and flow rate, improves hydrodynamic performance and reduces potential flow resistance through optimized design of the Tesla valve's structural dimensions. It minimizes the risk of microparticles entering the front-end wing-shaped branch pipe, and fine-tunes the structure in the main channel and rear-end wing-shaped branch areas prone to embolism, while also designing micro-chambers to collect impurity particles. This anti-embolism strategy provides a comprehensive and effective solution by guiding impurity particles at the front end, diverting fluid at the rear end, and collecting impurity particles. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 The model and simulation results of a single Tesla valve structure are presented.

[0015] Figure 2 This is a schematic diagram of an improved section of a single Tesla valve structure.

[0016] Figure 3 Simulation comparison diagram of fine-tuning design for a single Tesla valve structure.

[0017] Figure 4 Design and simulation of the structural wall of a single Tesla valve.

[0018] Figure 5 This is a schematic diagram of a single Tesla valve structure.

[0019] Figure 6 This is a schematic diagram of the distribution of a single Tesla valve structure array.

[0020] Figure 7 This is a schematic diagram of the overall structure of a Tesla-style valve-based microflow controller. Detailed Implementation

[0021] 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.

[0022] Before designing this invention, the first step is to identify the easily clogged areas of the Tesla valve structure. The specific process is as follows: (1) Geometric modeling of Tesla valve The Tesla valve unit structure used is as follows: Figure 1 As shown in section a, a four-stage Tesla valve geometric model was established based on the actual structure of the Tesla valve. A turbulence model (kinetic energy - dissipation rate, kW) was adopted. Figure 1 Part b defines the physical properties and boundary conditions of the fluid, such as inlet flow rate and outlet pressure.

[0023] Introduce particles representing microparticles into the model, set their initial position, size, and density, define the equations of motion for the particles, and consider the interaction between the fluid and the particles.

[0024] (2) Analysis of simulation results Figure 1 The color coding in section c indicates the magnitude of the fluid velocity. The color bars show the velocity range, from low velocity (blue) to high velocity (red). The velocity gradient, i.e., how the velocity changes in different regions, can be observed through color changes. The more dramatic the color change, the greater the velocity gradient.

[0025] Streamlines show the flow path of fluid within a Tesla valve. The density of the streamlines reflects the speed of fluid flow; the denser the streamlines, the faster the fluid velocity.

[0026] from Figure 1 As can be seen from part d, the distribution of particles within the Tesla valve exhibits a certain regularity. The particles are mainly concentrated in certain specific regions, which may be areas with lower fluid velocities or more complex fluid dynamics.

[0027] (3) Identification of embolism-prone areas Cluster area identification: Figure 1 In section d, the darker colored areas (such as blue and green) indicate areas with more severe particle aggregation. These areas are typically where the fluid velocity is low, possibly due to obstructed or slowed fluid flow. These areas are highly likely to become emboli of impurity particles.

[0028] Analysis of aggregation causes: The aggregation of microparticles in these areas may be due to fluid eddies, backflow, or other complex fluid dynamic phenomena. These phenomena may cause microparticles to remain or deposit in these areas.

[0029] (II) Implementation of the anti-embolism program (1) Tesla valve end wing-shaped main structure design and anti-embolism ① Wing-shaped main structure design scheme like Figure 2 As shown, fine-tuning optimizations were performed at four different locations, including adjusting the channel shape and adding flow guiding structures, to improve fluid flow characteristics and reduce the accumulation of microparticles in these areas.

[0030] Through local structural optimization, the anti-embolism performance of Tesla valves in easily embolized areas is significantly improved. The following section... Figure 2 The flow field streamline diagrams before and after structural fine-tuning at position c are analyzed using particle simulation. The effects of structural fine-tuning at the other three positions are similar to those at position c, and will not be elaborated upon here.

[0031] Adjust the parameters of the branch section so that the diameter of the branch section gradually increases from the inlet section to the branch straight pipe section. After expansion, the cross-sectional area of ​​the flow channel of the branch section is increased by 25% to 30% compared with the cross-sectional area of ​​the original corresponding area. Adjust the parameters of the first branch straight pipe section, changing the straight pipe of the first branch straight pipe section to an arc pipe to expand the area. The area of ​​the first branch straight pipe section after expansion increases by 20% to 30%. Adjust the parameters of the branch annular segment, reduce the inner diameter and expand the outer diameter. The inner diameter is reduced by 3% to 5% compared to before expansion, and the outer diameter is increased by 2% to 3% compared to before expansion. After expansion, the area of ​​the annular segment increases by 25% to 35%. Adjust the parameters of the outlet section and extend the flow channel axially along the axis of the main flow channel, with an expansion amount of 30% to 40% of the original length of the outlet section; ② Analysis and confirmation of anti-embolism performance like Figure 3 The particle simulation results show that in the original structure, particle aggregation at position c is quite significant. The improved structure optimizes the flow field, resulting in a more uniform particle distribution in the fluid and reducing particle aggregation at position c. This uniform particle distribution helps prevent particle blockage within the pipe, and the improved structure also enhances particle transport efficiency, allowing particles to flow more smoothly with the fluid and reducing their residence time within the pipe.

[0032] As shown in Table 1, the area ratio of the fine-tuned region to the original region is 1.32, indicating that the area of ​​the fine-tuned region has increased, which helps the fluid flow more smoothly. The number of particles in the fine-tuned region increased by 1.04% compared to the original region, but this increase did not significantly increase the risk of clogging. The particle density in the fine-tuned region decreased by approximately 21.212 (i.e., a reduction of 21.2%) compared to the original region, demonstrating the effectiveness of the fine-tuned region in reducing the risk of clogging.

[0033] Fine-tuning area / original area Area ratio Particle number ratio Particle density ratio numerical values 1.32 1.04 0.788 illustrate Increased surface area helps fluid flow more smoothly. A slight increase in the particle number ratio did not significantly increase the risk of clogging. The particle density in the fine-tuned region was reduced by approximately 21.2% compared to the original region, directly demonstrating the effectiveness of the fine-tuned region in reducing the risk of clogging. The fine-tuned C-structure effectively reduces particle density by increasing area and slightly increasing particle number, thereby reducing the risk of clogging. This design optimization facilitates smoother fluid flow while maintaining system stability and reliability. The fine-tuned C-structure demonstrates a significant advantage in reducing embolism risk and is of great importance for applications requiring precise fluid flow control.

[0034] ③ Analysis of the influence of pressure on flow field regulation performance The improved velocity streamline diagram at position c, with a more uniform velocity distribution, is shown below. Figure 3 As shown, the fluid velocity distribution is more uniform. In the original structure, there might be a region with a large velocity gradient at position c, meaning the fluid velocity changes drastically. In the improved structure, the velocity transition is smoother, the fluid flows more smoothly within the pipe, and the possibility of particle deposition near the wall is reduced, thus lowering the risk of embolism. Furthermore, simulation results show that, while maintaining a constant inlet velocity of 11.24 m / s, the fine-tuned c-structure design slightly reduces the inlet and outlet pressure drop from 7437 Pa in the original structure to 7192 Pa. This small pressure drop change indicates that although the fine-tuned c-structure has some impact on fluid dynamics performance, this impact is small and controllable, thus ensuring the stability and reliability of fluid dynamics performance.

[0035] (2) Tesla valve pipeline inner wall structure design anti-aging plug ① Design of the inner wall structure of the wing-shaped structure like Figure 4 As shown, the pipe structure is designed with a serrated shape in the region where wing-shaped molecular particles tend to accumulate in the Tesla valve. This serrated structure reduces their accumulation in the main channel, thereby lowering the risk of blockage in a single channel.

[0036] Micro-chambers are designed within Tesla valves to collect impurity particles from the fluid. These micro-chambers, with low permeability, are strategically placed within the Tesla valve to allow fluid passage while effectively capturing microparticles. By collecting these microparticles, their accumulation within the main channel is reduced, thereby lowering the risk of embolism while maintaining fluid flow efficiency.

[0037] ②Antiembolic performance analysis according to Figure 4 The simulation results show that the velocity streamline diagram reveals a decrease in flow velocity in the zigzag region, and the particle simulation diagram confirms that particles aggregate in this area, reducing the probability of blockage in the main channel. The microchamber also exhibits an aggregation effect in the particle simulation, with a particularly significant effect on particle collection. Most particles appear to be "sucked" into the chamber, indicating that the microchamber successfully collects the particles.

[0038] ③ Analysis of the influence of pressure on flow field regulation performance Simulation results show that the inlet velocity for both structural types is 11.24 m / s, indicating that the wall type has almost no effect on the fluid inlet velocity. The pressure drop is 750 Pa for the original wall, 613 Pa for the serrated wall, and 790 Pa for the micro-chamber structure. This demonstrates that although the serrated wall and micro-chamber were designed to optimize fluid flow and reduce the risk of embolism, their impact on the inlet and outlet pressure drops is not significant, and the changes in pressure drop are within acceptable limits compared to the original wall structure.

[0039] (III) Manufacturing and Packaging of Tesla-Inspired Microflow Controller for Resistance to Impurity Particle Embolism (1) Tesla valve structural unit design and manufacturing Figure 5 The diagram shows the structure of a single Tesla valve in a microchannel array, clearly illustrating the details of structural improvements within the microchannels, such as fine-tuning design, serrated design, and micro-chambers. These improvements are flexibly designed based on the specific conditions of easily clogged areas within the Tesla valve, aiming to enhance the reliability and durability of the entire system. Through these targeted design optimizations, clogging in fluid flow can be effectively reduced, ensuring the efficient operation of the microchannel array.

[0040] The unit Tesla valve piping uses Ti-6Al-4V titanium alloy powder with a particle size of 15-45μm, ensuring high strength, low density, and good corrosion resistance, meeting the stringent material performance requirements of the aerospace industry. Selective laser melting (SLM) technology is used to construct the piping layer by layer based on a CAD model. Printing parameters were optimized after verification with previous test pieces: laser power 250-300W, scanning speed 500-1000mm / s, layer thickness 0.05-0.1mm, and scanning spacing 0.1mm, ensuring high precision and good mechanical properties. After printing, the support structure is mechanically removed, followed by sandblasting to achieve a surface roughness below Ra 1.6μm. Chemical polishing is then performed to further improve surface smoothness and corrosion resistance. Figure 5 As shown.

[0041] (2) Design of unit array combination method Figure 6The diagram illustrates the distribution of microchannel units in an array. Four microchannel units are uniformly distributed in a circular array, with equal angles θ between each unit, indicating a symmetrical layout. In the diagram, θ is taken as 90°. Determining the number of units N is a crucial step in designing microchannels or any fluid control system, typically depending on the system's pressure drop requirements and desired flow rate. This design and layout facilitates efficient fluid flow and mixing in microchannel systems, while also potentially taking into account the need for ease of manufacture and maintenance. By precisely controlling the number N of control unit structures, the overall system performance can be optimized to meet the system's pressure drop and flow rate requirements.

[0042] (3) Microflow controller packaging Outer cylinder manufacturing: 7075-T6 aerospace-grade aluminum alloy is used. The aluminum alloy blank is rough-machined on a CNC lathe for preliminary shaping, leaving a certain machining allowance. The cylinder is then precision-machined and precision-milled to ensure dimensional accuracy ±0.02mm and roundness error ≤0.01mm. Threads are machined with tolerances controlled at 6H grade and surface roughness Ra within 1.6μm.

[0043] Surface treatment: Anodizing to improve the corrosion resistance of the cylinder.

[0044] End cap manufacturing: The end caps, made of the same material as the cylinder, are precision machined using turning and other processes to ensure dimensional accuracy and thread fit precision. Special attention is paid to machining the sealing surface, with flatness controlled within 0.01mm and roughness below Ra0.8μm.

[0045] Encapsulation: All components are ultrasonically cleaned to remove oil and particles, then wiped with alcohol to ensure a clean assembly environment. The pipe is placed into the cylinder, and aerospace-grade silicone rubber sealant is applied to the sealing surface. High-strength bolts are selected and tightened to the designed torque to ensure connection strength and sealing performance. The assembled diagram is as follows. Figure 7 As shown, the sealed cavity consists of an end cap 1 and a cylinder 3, and the Tesla valve array structure 3 is fixed to the end cap 1 by screws and nuts 4.

[0046] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on its differences from other embodiments. In particular, for the device embodiments, the above descriptions are merely preferred embodiments of the present invention. Since they are fundamentally similar to the method embodiments, the descriptions are relatively simple, and relevant parts can be referred to the descriptions of the method embodiments. The above descriptions are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention, without departing from the principle of the present invention, should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A Tesla valve structure type micro flow controller, comprising a Tesla valve array structure fixed in a sealed cylinder, the Tesla valve array structure is arrayed by a plurality of Tesla valves at equal intervals on a circumference, each Tesla valve comprises an inlet section, a flow dividing section, a branch straight pipe section, a branch annular section and an outlet section, the branch straight pipe section comprises a first branch straight pipe section and a second branch straight pipe section, the inlet of the branch annular section is connected to the outlet of the first branch straight pipe section, the outlet of the branch annular section is connected to the outlet section after converging with the outlet of the second branch straight pipe section, characterized in that: The pipe wall of the first branch straight pipe section is arc-shaped structure, and a sawtooth structure is arranged on the pipe wall; the second branch straight pipe section is provided with a micro chamber.

2. The Tesla valve structured micro-flow controller of claim 1, wherein: The diameter of the flow distribution section gradually increases from the inlet section to the branch straight pipe section.

3. A method of fabricating a micro flow controller of the Tesla valve configuration, characterized in that The method comprises the following steps: 1) modeling the existing Tesla valve structure, and adjusting the model parameters as follows: 1.1) adjusting the flow distribution section parameters, so that the diameter of the flow distribution section gradually increases from the inlet section to the branch straight pipe section, and the cross-sectional area of the flow passage of the expanded flow distribution section is expanded by 25% to 30% compared with the corresponding area before expansion; 1.2) adjusting the first branch straight pipe section parameters, changing the straight pipe of the first branch straight pipe section to an arc pipe to expand the area, and the expanded area of the first branch straight pipe section is increased by 20% to 30%, and a sawtooth structure is designed on the pipe wall; 1.3) adjusting the second branch straight pipe section parameters, increasing the micro chamber on the inner wall of the second branch straight pipe section; 1.4) adjusting the branch annular section parameters, reducing the inner diameter and expanding the outer diameter, the inner diameter is reduced by 3% to 5% compared with before expansion, and the outer diameter is increased by 2% to 3% compared with before expansion, and the area of the expanded annular section is increased by 25% to 35%; 1.5) adjusting the outlet section parameters, extending the flow passage in the axial direction along the axis of the main flow passage, and the expansion amount is 30% to 40% of the original length of the outlet section; 2) selecting materials and layering and constructing the pipeline according to the CAD model by using 3D printing technology; 3) setting the printing parameters, preparing a single Tesla valve structure, and performing surface treatment; 4) combining multiple Tesla valve structure arrays, fixing them in a sealed cylinder, and forming a Tesla valve structure type micro flow controller.

4. The method of claim 1, wherein the method further comprises: The material selected in step 2 is Ti-6Al-4V titanium alloy powder with a particle size of 15-45μm, and the selected 3D printing technology is selective laser melting (SLM) technology.

5. The method of claim 1, wherein the method further comprises: The printing parameters in step 3 are: laser power 250-300W, scanning speed 500-1000mm / s, layer thickness 0.05-0.1mm, and scanning interval 0.1mm.

6. The method of claim 1, wherein the method further comprises: The surface treatment process in step 3 is as follows: first, mechanically remove the support structure, then use sandblasting to make the surface roughness less than Ra1.6μm, and then perform chemical polishing.

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