Method for obtaining critical value of reynolds number of two-phase flow polishing medium, two-phase flow polishing method

Abstract

The present application relates to a kind of two-phase flow polishing medium reynolds number critical value acquisition method, two-phase flow polishing method, reynolds number critical value acquisition method includes the following steps: obtaining the flow channel caliber of micro internal flow channel structure, and the fluid viscosity of two-phase flow polishing medium, liquid phase density, abrasive grain size, abrasive grain mass concentration;Obtain the flow velocity and abrasive grain flow state when two-phase flow polishing medium is polished to micro internal flow channel structure;The reynolds number of two-phase flow polishing medium is calculated using flow channel caliber, fluid viscosity, liquid phase density, abrasive grain size, abrasive grain mass concentration and flow velocity;Determine the reynolds number critical value of two-phase flow polishing medium in combination with the flow state of abrasive grain, and the interval formed by reynolds number critical value is used as reynolds number control interval.This method realizes the key technology that high-efficiency polishing efficiency is compatible with while avoiding the "bullet flow" texture of two-phase flow polishing medium to surface over-polishing after polishing to micro complex internal flow channel.

Description

Technical Field

[0001] This invention belongs to the field of precision machining technology, specifically relating to a method for obtaining the critical value of the Reynolds number of a two-phase flow polishing medium and a two-phase flow polishing method. Background Technology

[0002] Components with micro-fine internal flow channels with a diameter ≤3mm and a length-to-diameter ratio >50:1 have wide applications in aerospace, shipbuilding, nuclear, and automotive fields, such as engine fuel nozzles, hydraulic components, and heat exchangers. The micro-fine complex internal flow channels can perform functions such as fluid transport, exchange, or application of hydraulic pressure.

[0003] Currently, the main processing technologies for micro-inner channel structures with a diameter ≤3mm and an aspect ratio >50:1 include precision machining, femtosecond / water-guided / long-pulse laser processing, electrical discharge machining, and additive manufacturing (3D printing). However, processing the surface of micro-complex inner channels using these technologies can lead to problems such as burrs, residues of adhering powder and sintered particles, rough surfaces, and remelted layers, severely impacting the service life, safety, and stability of the components. Therefore, certain surface finishing techniques are necessary to eliminate these adverse effects and meet product performance requirements.

[0004] Finishing micro-internal flow channel structures with a diameter ≤3mm and an aspect ratio >50:1 is a challenge in the metal manufacturing industry. It requires consideration of deburring, improving hole shape, chamfering and profile accuracy, surface powder removal, reducing or removing remelted layers, and polishing. The lack of effective polishing methods for such internal flow channels has become one of the key technical bottlenecks restricting the widespread application of these fluid components in the industrial field. For such micro-complex flow channel structures, water-based two-phase flow is currently a relatively ideal finishing method. Patent CN202210659821.0 describes a water-based two-phase flow finishing method that uses a low-viscosity water-based polishing medium (η<200cP) to improve its high fluidity in micro-complex internal flow channels. Under high speed and high pressure, the low-viscosity water-based polishing medium moves at high speed within the internal flow channel. The abrasive particles frequently collide with the wall surface under the action of the high-speed fluid movement, thus achieving high-speed, high-frequency micro-cutting to polish the wall surface, while simultaneously achieving effective fluid conformal micro-shaping. Water-based two-phase flow polishing is a physical polishing method with numerous significant advantages, including high passability and applicability to internal flow channel structures, high processing efficiency, no damage to the substrate structure, no heat-affected zone, and high polished surface quality. It is a green, low-carbon, and environmentally friendly technology that is dust-free, low-noise, and free of chemical pollution. For micro-complex internal flow channel structures, water-based two-phase flow polishing can significantly overcome the limitations of common polishing methods, such as low efficiency of chemical polishing, difficulty in placing contour electrodes in narrow flow channels for electrochemical polishing, poor passability of abrasive flow viscoelastic polishing media, water jets only acting on the surface area close to the nozzle, limited magnetorheological polishing, and magnetic field distribution only applicable to regular flow channel structures.

[0005] However, further engineering applications show that when polishing water-based two-phase flows with complex, micro-sized internal channels, especially when dealing with channels of different materials and structures, high flow velocities and pressures exceeding a certain critical value often result in "bullet-flow" pitting patterns on the polished channel surface. This leads to a significant decrease in surface quality and a substantial increase in roughness due to these pitting patterns. Conversely, when relatively conservative, lower values ​​are chosen for flow velocities and pressures, polishing efficiency decreases significantly. Given the wide variety of materials and structures used in micro-sized internal channels, engineering profiling and trial-and-error methods to find the optimal values ​​for flow velocities and pressures severely impact experimental costs, economics, timeliness, and accuracy, and lack reliability and universality. Summary of the Invention

[0006] To address the aforementioned problems in the prior art, this invention provides a method for obtaining the critical Reynolds number of a two-phase flow polishing medium and a two-phase flow polishing method. The technical problem to be solved by this invention is achieved through the following technical solution:

[0007] This invention provides a method for obtaining the Reynolds number critical value of a two-phase flow polishing medium. The two-phase flow polishing medium includes a liquid-solid two-phase flow polishing medium. The liquid phase includes a water-based Newtonian fluid, a water-based non-Newtonian fluid, an oil-based fluid, or an organic fluid; the solid phase includes abrasive particles. The two-phase flow polishing medium is used to perform surface finishing on a micro-internal flow channel structure under the condition of satisfying a controllable range constituted by the Reynolds number critical value. The method includes the following steps:

[0008] Obtain the flow channel diameter of the micro-internal flow channel structure, as well as the fluid viscosity, liquid phase density, abrasive particle size, and abrasive particle mass concentration of the two-phase flow polishing medium;

[0009] The flow rate and flow state of the abrasive particles were obtained when the two-phase flow polishing medium polished the micro-internal flow channel structure.

[0010] The Reynolds number of the two-phase flow polishing medium is calculated using the channel diameter, fluid viscosity, liquid phase density, abrasive particle size, abrasive mass concentration, and flow velocity.

[0011] The critical Reynolds number of the two-phase flow polishing medium is determined by combining the flow state of the abrasive particles, and the interval formed by the critical Reynolds number is used as the Reynolds number control interval.

[0012] In one embodiment of the present invention, obtaining the flow rate and abrasive grain flow state when the two-phase flow polishing medium polishes the micro-internal flow channel structure includes:

[0013] The flow velocity of the two-phase flow polishing medium and the flow state of the abrasive particles during polishing of the micro-internal flow channel structure are monitored using hydrodynamic characteristic detection technology, including tracer particle flow display technology and high-speed imaging technology; when the flow state of the abrasive particles reaches the bullet-shaped flow state, the flow velocity of the two-phase flow polishing medium is measured using a Doppler ultrasonic velocity meter.

[0014] In one embodiment of the present invention, the Doppler ultrasonic flow meter includes an ultrasonic emission source, a transducer, and a Doppler non-contact flow meter, wherein,

[0015] The ultrasonic transmitter is used to transmit ultrasonic signals using sonar technology, and the transmission frequency of the ultrasonic signal is <15KHz.

[0016] The transducer is used to convert the ultrasonic signal into a vibration signal to drive the two-phase flow polishing medium to perform ultrasonic vibration, wherein the power density of the vibration signal is >150W / cm². 2 The amplitude is greater than 60μm;

[0017] The Doppler non-contact flow meter is used to measure the flow velocity of the two-phase flow polishing medium using the Doppler effect;

[0018] The flow rate accuracy error of the Doppler ultrasonic flow meter is <0.5%.

[0019] In one embodiment of the present invention, the Reynolds number calculation formula for the two-phase flow polishing medium is as follows:

[0020]

[0021] Where Re* is the Reynolds number of the two-phase flow polishing medium, ρ is the liquid density, v is the flow velocity, d is the channel diameter, w is the abrasive particle mass concentration, μ is the fluid viscosity, and d s The abrasive grain size is denoted as .

[0022] In one embodiment of the present invention, the Reynolds number critical value of the two-phase flow polishing medium is determined in conjunction with the flow state of the abrasive particles, and the interval formed by the Reynolds number critical values ​​is used as the Reynolds number control interval, including:

[0023] The Reynolds number at which the liquid phase carrying the abrasive particles changes from laminar to turbulent flow in the micro-internal flow channel structure is taken as the first Reynolds number critical value. The Reynolds number at which the flow state of the abrasive particles reaches the bullet flow state is taken as the second Reynolds number critical value. The interval formed by the first Reynolds number critical value and the second Reynolds number critical value is taken as the Reynolds number control interval.

[0024] In one embodiment of the present invention, when the liquid phase is a water-based Newtonian fluid or a water-based non-Newtonian fluid, the Reynolds number control range is greater than 4000 and less than 9000; when the liquid phase is an oil-based fluid, the Reynolds number control range is greater than 5000 and less than 12000; when the liquid phase is an organic fluid, the Reynolds number control range is greater than 5000 and less than 10000.

[0025] In one embodiment of the present invention, when the micro-internal flow channel structure includes a CoCrMo alloy S-type flow channel with a flow channel diameter of 1-2.5 mm and an aspect ratio of 100, and the liquid phase includes an aqueous liquid phase, the density of the liquid phase is 2-20 kg / cm³. 3 The two-phase flow polishing medium has a fluid viscosity of 20–120 Cp, the abrasive grains have an average particle size of 20–50 μm, the abrasive grain mass concentration is 30–80 g / L, and the two-phase flow polishing medium has a flow rate of 10–20 m / s.

[0026] Another embodiment of the present invention provides a two-phase flow polishing method using turbulence control, comprising:

[0027] Under the condition of satisfying the Reynolds number control range, the micro-internal flow channel structure is polished using a liquid-solid two-phase flow polishing medium, wherein the Reynolds number control range is determined by the acquisition method described in the above embodiment.

[0028] In one embodiment of the present invention, the driving pressure of the liquid-solid two-phase flow polishing medium is 0.5MPa to 1.5MPa, and the polishing time is 60min to 80min.

[0029] Another embodiment of the present invention provides a micro-internal flow channel workpiece, which is obtained by polishing using the two-phase flow polishing method described in the above embodiments.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] This invention first clarifies that the Reynolds number of the two-phase flow polishing medium is a key influencing factor affecting the flow state of two-phase flow solid abrasive particles. Based on this, the Reynolds number of the two-phase flow polishing medium is calculated using the relevant parameters of the micro-internal flow channel structure and the two-phase flow polishing medium. Combined with the flow state of the abrasive particles, the critical Reynolds number is determined, and a method for obtaining the critical Reynolds number value of the two-phase flow polishing medium is established. When the high-speed two-phase flow polishing medium is used to polish micro-internal flow channels of different materials and structures under the condition of satisfying the control range constituted by the critical Reynolds number value, the resulting micro-internal flow channel structure has an overall smooth and flat surface with low average surface roughness and no obvious "bullet flow" pit texture. This invention achieves a key technical method that combines high polishing efficiency with avoiding the "bullet flow" pit texture caused by over-polishing of the surface after polishing micro-complex internal flow channels by the two-phase flow polishing medium. This method has the advantages of low cost, high accuracy, and high reliability. Attached Figure Description

[0032] Figure 1 A flowchart illustrating a method for obtaining the critical Reynolds number of a two-phase flow polishing medium, provided in an embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of the surface microstructure of the flow channel after polishing under a Reynolds number Re* of 8300.

[0034] Figure 3 This is a schematic diagram of the surface morphology of the flow channel after polishing, given a Reynolds number Re* of 5530. Detailed Implementation

[0035] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0036] Example 1

[0037] Two-phase flow technology utilizes a low-viscosity liquid-phase polishing medium (liquid phase viscosity η < 200 cP) to enhance its high fluidity in complex internal flow channels. Simultaneously, it significantly increases the hydraulic thrust of the equipment, causing the low-viscosity liquid-phase polishing medium to undergo high-speed turbulent motion within the internal flow channels. Driven by fluid turbulence, abrasive particles frequently collide with the wall surface at a certain angle of attack, greatly increasing particle aggregation and distribution near the wall surface and generating high-speed, high-frequency cutting of the wall material, ultimately achieving effective, conformal polishing. This embodiment reveals that the turbulence level of the two-phase flow polishing medium should not be too high, as excessive turbulence can easily lead to turbulent instability. The main core factor affecting the turbulence level is the combined Reynolds number Re* of the solid and liquid phases of the water-based two-phase flow polishing medium. That is, the higher the turbulence level of the two-phase flow polishing medium, the larger the Reynolds number Re*, and the more pronounced the bullet-shaped flow pattern generated by the aggregation of solid abrasive particles in the flow field. This easily produces a "bullet flow" pitted texture morphology after polishing the surface of the micro-internal flow channel structure.

[0038] It should be noted that the Reynolds number Re* of the two-phase flow polishing medium mentioned in this embodiment refers to the combined Reynolds number Re* of the two-phase flow of liquid phase and abrasive solid phase, not the Reynolds number Re of pure liquid phase.

[0039] Since the Reynolds number Re* of the two-phase flow polishing medium is a key influencing factor affecting the flow state of solid-phase abrasive particles in two-phase flow, this embodiment obtains an empirical formula for the Reynolds number Re* of the two-phase flow polishing medium based on engineering data, and thus clarifies the core parameter control method of the turbulence state in two-phase flow on the "bullet flow" texture.

[0040] The empirical formula for the Reynolds number Re* of a two-phase flow polishing medium is:

[0041]

[0042] Where ρ is the liquid density, v is the flow velocity, d is the channel diameter, w is the abrasive particle mass concentration, μ is the fluid viscosity, and d s The abrasive grain size is denoted as .

[0043] It is evident that the core parameters of the Reynolds number Re* for two-phase flow polishing media include liquid phase density ρ, flow velocity υ, fluid viscosity μ, and channel diameter d, as well as the abrasive solid phase parameter, i.e., abrasive particle size d. s The abrasive particle mass concentration w. By adjusting these core parameters, the turbulence state of the two-phase flow polishing medium can be controlled, thereby achieving the control of the "bullet flow" texture.

[0044] Based on the known core parameter of Reynolds number Re*, this embodiment develops a method for obtaining the critical value of Reynolds number Re* for two-phase flow polishing media with different materials and structures in micro-internal channels.

[0045] The two-phase flow polishing medium in this embodiment includes a liquid phase and a solid phase two-phase flow polishing medium.

[0046] Liquid phases, provided the viscosity η < 200 cP, include, but are not limited to, water-based Newtonian fluids, water-based non-Newtonian fluids, oil-based fluids, or organic fluids. Water-based liquid phases (including water-based Newtonian and water-based non-Newtonian fluids) refer to deionized water with the addition of a certain viscosity enhancer to give it a specific viscosity. Oil-based fluids include, but are not limited to, mineral oil or vegetable oil fluids, and organic fluids include, but are not limited to, cyclohexane or cyclohexanone fluids.

[0047] The solid phase includes abrasive particles, which can be one or more of carbide ceramics, oxide ceramics, nitride ceramics, and natural minerals. Carbide ceramics include silicon carbide and tungsten carbide; oxide ceramics include alumina, zirconium oxide, and cerium oxide; nitride ceramics include boron nitride and chromium nitride; and natural minerals include diamond / sand, mica, quartz, and olivine. For example, silicon carbide is used as the abrasive material.

[0048] The two-phase flow polishing medium in this embodiment is used to perform surface finishing on micro-internal flow channel structures under the condition of satisfying the control range formed by the Reynolds number critical value.

[0049] Please see Figure 1 , Figure 1 This is a flowchart illustrating a method for obtaining the critical Reynolds number of a two-phase flow polishing medium, provided in an embodiment of the present invention. The method includes the following steps:

[0050] S1. Obtain the flow channel diameter of the micro-internal flow channel structure, as well as the fluid viscosity, liquid phase density, abrasive particle size, and abrasive particle mass concentration of the two-phase flow polishing medium.

[0051] Specifically, the flow channel diameter d of the micro-internal flow channel structure is measured using measuring tools such as vernier calipers. The volume of the liquid phase is measured, and the total mass w1 of the liquid phase is weighed using an electronic balance to calculate the liquid phase density ρ. The total mass w2 of the abrasive particles is weighed, and the average particle size d of the abrasive particles is measured using a laser particle size analyzer. s The viscosity μ of the two-phase flow polishing medium was measured using a Brinell viscometer. The abrasive particle mass concentration was calculated using the total mass w2 of the liquid phase and the total volume v of the two-phase flow polishing medium.

[0052] For example, the micro-internal flow channel structure is a transparent tubular sample manufactured using a 3D printing device based on stereolithography apparatus (SAL). The micro-internal flow channel structure can also be fabricated using precision machining, femtosecond / water-conducting / long-pulse laser processing, electrical discharge machining, and other forming and processing technologies.

[0053] S2. Obtain the flow rate and abrasive particle flow state when the two-phase flow polishing medium polishes the micro-internal flow channel structure.

[0054] Specifically, fluid dynamics detection technology, including tracer particle flow display technology and high-speed imaging technology, is used to monitor the flow velocity of the two-phase flow polishing medium and the flow state of the abrasive particles during the polishing of the micro-internal flow channel structure. When the flow state of the abrasive particles reaches the bullet-shaped flow state, the flow velocity of the two-phase flow polishing medium is measured using a Doppler ultrasonic velocity meter.

[0055] Tracer particle flow visualization technology is a technique that utilizes the dye line method to monitor the flow characteristics of a flow field in real time. High-speed imaging technology is a means of visualizing the flow of tracer particles in a three-dimensional volume using a high-speed camera. Integrating tracer particle flow visualization technology and high-speed imaging technology into fluid dynamics characteristic detection technology enables precise dynamic monitoring of the flow velocity and abrasive flow regime of a two-phase flow polishing medium. Specifically, it allows for the observation of instantaneous images of particle motion vectors, particle vorticity, and abrasive particle distribution characteristics at the inlet, middle, and outlet of a transparent pipe under different pressure and flow velocity conditions, thereby obtaining the flow velocity and abrasive flow regime of the two-phase flow polishing medium. The fluid dynamics characteristic detection technology, including tracer particle flow visualization technology and high-speed imaging technology, is implemented using existing technologies and will not be elaborated upon here.

[0056] The flow regime of abrasive particles changes with the flow state of the liquid phase. When the liquid phase exhibits laminar flow, the liquid phase carries the abrasive particles in an orderly and regular flow within the inner channel; when the liquid phase exhibits turbulent flow, the abrasive particles frequently collide with the channel wall under the driving force of fluid turbulence; when the liquid phase exhibits a strong degree of turbulence, the abrasive particles agglomerate significantly in a localized manner, forming a distinct bullet-shaped flow regime.

[0057] Furthermore, the flow velocity of the two-phase flow polishing medium and the flow state of the abrasive particles during the polishing of the micro-internal flow channel structure are monitored using tracer particle flow display technology and high-speed imaging technology. The flow velocity is continuously increased until the flow state of the abrasive particles reaches the bullet-shaped flow state. Then, the flow velocity of the two-phase flow polishing medium is measured using a Doppler ultrasonic flow meter.

[0058] In one specific embodiment, the Doppler ultrasonic flow meter includes an ultrasonic emission source, a transducer, and a Doppler non-contact flow meter.

[0059] An ultrasonic transmitter is used to emit ultrasonic signals using sonar technology. A transducer converts the ultrasonic signal into a vibration signal to drive the two-phase flow polishing medium to undergo ultrasonic vibration. A Doppler non-contact flow meter is used to measure the flow velocity of the two-phase flow polishing medium using the Doppler effect.

[0060] It should be noted that the ultrasonic transmitter in this embodiment is a high-energy ultrasonic transmitter, capable of emitting ultrasonic signals with a frequency <15kHz. A high-load, large-amplitude transducer is selected to achieve an amplitude greater than 60μm and a power density >150W / cm². 2 The vibration signal. Based on the selection of a high-energy ultrasonic emission source and a high-load, large-amplitude transducer, the Doppler ultrasonic flow meter achieves a flow rate accuracy error of <0.5% in a two-phase flow polished medium environment.

[0061] Existing flow meters use ultrasonic transmitters and Doppler non-contact flow meters to measure flow velocity and flow rate, achieved through an ultrasonic transmitter and receiver. The ultrasonic transmitter and receiver can be installed inside or outside the pipe. In-pipe installation is more accurate, but in two-phase flow, abrasive particles inside the pipe can erode and damage the ultrasonic transmitter and receiver. When installed externally, the ultrasonic flow meter typically emits at a frequency greater than 16 kHz; higher frequencies weaken the penetration of abrasive particles. The ultrasonic amplitude and power density (0.5 W / cm²) of the ultrasonic flow meter are also relevant. 2 The lower density of the ultrasonic velocity meter results in weaker penetration. Existing flow meters require a pipe wall thickness of <1mm and a low number of solid particles to ensure accurate measurement. However, the Doppler ultrasonic flow meter in this embodiment uses high-energy sonar emission technology to achieve an ultrasonic emission frequency of <15kHz, combined with a high-load, large-amplitude transducer to achieve an amplitude greater than 60μm and a power density >150W / cm². 2 The vibration signal of the Doppler ultrasonic flow meter makes the flow rate accuracy error of the two-phase flow polishing medium less than 0.5%. This accuracy error is much smaller than the 2% accuracy of conventional ultrasonic flow meters. This solves the defect of conventional Doppler ultrasonic flow meters that can hardly monitor the flow rate of high-speed two-phase flow, and realizes the flow rate monitoring of high-speed two-phase flow polishing medium.

[0062] S3. Calculate the Reynolds number of the two-phase flow polishing medium using the channel diameter, fluid viscosity, liquid phase density, abrasive particle size, abrasive mass concentration, and flow velocity.

[0063] Specifically, the Reynolds number Re* of the two-phase flow polishing medium under different states is calculated using the empirical formula for the Reynolds number Re*. These different states can include: State 1: The liquid phase carrying abrasive particles flows in an orderly and regular manner within the inner channel; State 2: The liquid phase carrying abrasive particles transitions from laminar to turbulent flow within the inner channel; State 3: The liquid phase carrying abrasive particles undergoes turbulent motion within the inner channel, and the abrasive particles frequently collide with the wall under the driving force of fluid turbulence; State 4: The liquid phase carrying abrasive particles undergoes high-speed turbulent motion within the inner channel, and the abrasive particles significantly and locally aggregate to form a distinct bullet-shaped flow pattern.

[0064] S4. Determine the critical Reynolds number of the two-phase flow polishing medium by combining the liquid phase flow state of the two-phase flow polishing medium and the flow state of the abrasive particles. The range formed by the critical Reynolds number is used as the Reynolds number control range.

[0065] Specifically, in state 3, where the liquid phase carries abrasive particles in turbulent motion within the inner channel, and the abrasive particles frequently collide with the wall under the driving force of fluid turbulence, the aggregation and distribution of particles near the wall is significantly increased, resulting in high-speed, high-frequency cutting of the wall material, ultimately achieving effective, conformal polishing. Therefore, the Reynolds number at state 2, where the liquid phase carries abrasive particles and transitions from laminar to turbulent flow within the inner channel, is taken as the first Reynolds number critical value, which is the lower limit. The Reynolds number at state 4, where the liquid phase carries abrasive particles in high-speed turbulent motion within the inner channel, and the abrasive particles significantly aggregate locally to form a distinct bullet-shaped flow pattern, is taken as the second Reynolds number critical value, which is the upper limit. The interval formed by the first and second Reynolds number critical values ​​is designated as the Reynolds number control interval. Within this control interval, the liquid phase carries abrasive particles in turbulent motion within the inner channel, and the abrasive particles frequently collide with the wall under the driving force of fluid turbulence, achieving effective, conformal polishing.

[0066] In one specific embodiment, when the liquid phase is a water-based Newtonian fluid or a water-based non-Newtonian fluid, the Reynolds number control range is greater than 4000 and less than 9000. When the liquid phase is an oil-based fluid, the Reynolds number control range is greater than 5000 and less than 12000. When the liquid phase is an organic fluid, the Reynolds number control range is greater than 5000 and less than 10000.

[0067] When the Reynolds number Re* of the water-based two-phase flow polishing medium is less than or equal to 4000, it cannot effectively polish the surface of the fine internal flow channels of metal. This is because when the Reynolds number of the water-based two-phase flow polishing medium is below 4000, the water-based liquid phase exhibits a laminar flow pattern. The water-based liquid phase carries abrasive particles in an orderly and regular flow within the internal flow channels, which cannot promote multi-angle collisions and effective cutting between the abrasive particles and the flow channel walls. When the turbulence level, i.e., the Reynolds number Re*, is greater than or equal to 9000, the turbulence is too strong, and the abrasive particles accumulate locally to form a significant bullet-shaped flow pattern. This results in a "bullet flow" texture with high roughness appearing on the surface of the fine internal flow channels after polishing with water-based two-phase flow. Therefore, this embodiment selects a range greater than 4000 and less than 9000 as the Reynolds number control range for the water-based two-phase flow polishing medium.

[0068] It should be noted that the Reynolds number control range of water-based two-phase flow polishing media, greater than 4000 and less than 9000, is universal; that is, this Reynolds number control range is applicable to micro-internal channels with different materials and structures. Specifically, the diameter of the micro-internal channel is ≤3mm, the length-to-diameter ratio is >50:1, and the materials of the micro-internal channel include, but are not limited to, CoCrMo high-temperature alloys, titanium alloys, steel, ceramics, aluminum alloys, and polymer materials. The structure of the micro-internal channel includes, but is not limited to, three-dimensional spatially oriented structures with S-shaped bends, L-shaped bends, U-shaped bends, O-shaped bends, spiral bends, and other turning structures, or straight structures. For a micro-internal channel of a single material and structure, the Reynolds number control range needs to be calculated by combining the basic conditions of bullet flow control for abrasive particles with Reynolds numbers of 4000 < Re* < 9000 with the core parameter of the comprehensive Reynolds number Re* of the two-phase flow polishing medium.

[0069] Preferably, considering the basic conditions for bullet flow control of abrasive particles with a turbulent Reynolds number of 4000 < Re* < 9000, when the micro-internal flow channel structure includes a CoCrMo high-temperature alloy S-type flow channel with a diameter d of 1–2.5 mm and an aspect ratio of 100, and the liquid phase includes a water-based liquid phase, the density ρ of the water-based liquid phase is 2–20 kg / cm³. 3 The viscosity μ of the two-phase flow polishing medium is 20–120 Cp, and the average particle size d of the abrasive grains is... s The Reynolds number control range of the CoCrMo high-temperature alloy S-type flow channel is calculated based on the following conditions: the particle size is 20-50 μm, the abrasive particle mass concentration w is 30-80 g / L, and the flow velocity v of the two-phase flow polishing medium is 10-20 m / s.

[0070] Similarly, when the Reynolds number Re* of the oil-based two-phase flow polishing medium is less than or equal to 5000, it cannot effectively polish the surface of the metal micro-channels. When it is greater than or equal to 12000, the abrasive particles agglomerate significantly in a localized manner, forming a distinct bullet-shaped flow pattern. This results in a "bullet flow" texture with high roughness on the surface of the micro-channels after polishing with oil-based two-phase flow. Therefore, a range greater than 5000 and less than 12000 is selected as the Reynolds number control range for the oil-based two-phase flow polishing medium, and this control range has universality.

[0071] When the Reynolds number Re* of the organic two-phase flow polishing medium is less than or equal to 5000, it cannot effectively polish the surface of the metal micro-channels. When it is greater than or equal to 10000, the abrasive particles aggregate significantly in a localized manner, forming a distinct bullet-shaped flow pattern. This results in a "bullet flow" texture with high roughness on the surface of the micro-channels after polishing with organic two-phase flow. Therefore, a range greater than 5000 and less than 10000 is selected as the Reynolds number control range for the organic two-phase flow polishing medium, and this control range has universality.

[0072] This embodiment first clarifies that the Reynolds number of the two-phase flow polishing medium is a key influencing factor affecting the flow state of two-phase flow solid abrasive particles. Based on this, the Reynolds number of the two-phase flow polishing medium is calculated using the relevant parameters of the micro-internal flow channel structure and the two-phase flow polishing medium. Combined with the abrasive flow state, the critical Reynolds number is determined, and a method for obtaining the critical value of the Reynolds number of the two-phase flow polishing medium is established. When the high-speed two-phase flow polishing medium is used to polish micro-internal flow channels of different materials and structures under the condition of satisfying the control range formed by the critical value of the Reynolds number, the resulting micro-internal flow channel structure has an overall smooth and flat surface with low average surface roughness and no obvious "bullet flow" texture. This achieves the key technology of achieving both polishing efficiency and avoiding the "bullet flow" texture caused by over-polishing of the surface after polishing micro-complex internal flow channels by the two-phase flow polishing medium. This method has the advantages of low cost, high accuracy, and high reliability.

[0073] Example 2

[0074] Based on Example 1, this example provides a polishing method using a two-phase flow controlled by turbulence. Specifically, this method includes polishing a micro-internal flow channel structure using a liquid-solid two-phase flow polishing medium, under conditions satisfying the Reynolds number control range. The Reynolds number control range is determined using the method of Example 1.

[0075] The two-phase flow polishing medium in this embodiment includes a liquid-solid two-phase flow polishing medium. The liquid phase, provided the viscosity η < 200 cP, includes, but is not limited to, water-based Newtonian fluids, water-based non-Newtonian fluids, oil-based fluids, or organic fluids. The water-based liquid phase refers to deionized water with the addition of a certain viscosity enhancer. The solid phase includes abrasive particles, which can be one or more of carbide ceramics, oxide ceramics, nitride ceramics, and natural minerals. Carbide ceramics include silicon carbide, tungsten carbide, etc.; oxide ceramics include alumina, zirconium oxide, cerium oxide, etc.; nitride ceramics include boron nitride, chromium nitride, etc.; and natural minerals include diamond / sand, mica, quartz, olivine, etc.

[0076] The micro-internal flow channel structure of this embodiment has an aperture ≤3mm and an aspect ratio >50:1. The micro-internal flow channel structure can be made of different materials and has different structures. For example, the materials for the micro-internal flow channel include, but are not limited to, CoCrMo high-temperature alloys, titanium alloys, steel, ceramics, aluminum alloys, and polymer materials. The structures of the micro-internal flow channel include, but are not limited to, three-dimensional spatially oriented structures with S-shaped bends, L-shaped bends, U-shaped bends, O-shaped bends, spiral bends, etc., or straight structures. Micro-internal flow channels made of different materials and with different structures have different Reynolds number control ranges.

[0077] Specifically, the driving pressure of the liquid-solid two-phase flow polishing medium is 0.5 MPa to 1.5 MPa, and the polishing time is 60 min to 80 min. For example, the driving pressure of the liquid-solid two-phase flow polishing medium is 1.2 MPa, and the polishing time is 60 min.

[0078] Example 3

[0079] Based on Example 2, this example provides a micro-internal flow channel workpiece. This micro-internal flow channel workpiece is obtained by polishing using the polishing method of Example 2.

[0080] Specifically, the average surface roughness of the flow channel of the micro-internal flow channel workpiece is 2.3μm to 3.0μm.

[0081] In this embodiment, the surface roughness of the micro-internal flow channel workpiece is low, the flow channel is smooth and flat as a whole, and no obvious "bullet flow" pattern appears.

[0082] Example 4

[0083] Based on Examples 1, 2, and 3, this example uses a typical S-shaped flow channel of CoCrMo high-temperature alloy and a water-based two-phase flow polishing medium as examples to compare and illustrate the two-phase flow polishing method using turbulence control.

[0084] Specifically, for a typical S-shaped flow channel of CoCrMo high-temperature alloy with a diameter of 2.5mm and an aspect ratio of approximately 100, a scale-up transparent pipe sample was manufactured using SLA photopolymerization 3D printing equipment. A water-based two-phase flow polishing medium was prepared using silicon carbide as the abrasive material. The density ρ of the water-based liquid phase was weighed and calculated using an electronic balance to be 4 kg / cm³. 3 The viscosity μ of the polishing medium was measured to be 55 Cp using a Brinell viscometer, the flow channel diameter d was measured to be 2.5 mm using vernier calipers, and the average particle size d of the abrasive particles was measured using a laser particle size analyzer. s The abrasive particle size is 50 μm, and the abrasive particle mass concentration w is 80 g / L.

[0085] A fluid dynamics characteristic detection platform incorporating tracer particle flow display technology and high-speed imaging technology was used to observe instantaneous images of particle motion vectors, particle motion vorticity, and abrasive particle group distribution characteristics at the inlet, middle, and outlet of a transparent pipeline under different pressure and flow velocity conditions. When the flow velocity v of the water-based two-phase flow polishing medium exceeds 15 m / s, the solid-phase abrasive particle elastodynamic state is significant. The calculated Reynolds number critical value Re* for solid-phase abrasive particle elastodynamic state control is approximately 6900.

[0086] Under conditions exceeding the critical driving pressure of 1.1 MPa, with a flow velocity of 18 m / s and a Re* of approximately 8300, the CoCrMo high-temperature alloy sample was polished using a water-based two-phase flow polishing medium. The driving pressure of the polishing medium was 1.5 MPa, and the polishing time was 60 min. The surface morphology of the flow channel after polishing is shown in the figure below. Figure 2 As shown, Figure 2 This is a schematic diagram of the surface morphology of the flow channel after polishing, given a Reynolds number Re* of 8300. Figure 2 In the process, the "bullet flow" pit texture is more prominent. The average surface roughness of the flow channel before polishing is about 11.2 μm, and the average surface roughness of the flow channel after polishing is about 28.6 μm.

[0087] Meanwhile, at a pressure 1.1 MPa below the critical driving pressure, with a flow velocity of 12 m / s and a Re* of approximately 5530, the CoCrMo high-temperature alloy sample was polished using a water-based two-phase flow polishing medium. The driving pressure of the polishing medium was 0.5 MPa, and the polishing time was 60 min. The surface morphology of the flow channel after polishing is shown in the figure below. Figure 3 As shown, Figure 3 This is a schematic diagram of the surface morphology of the flow channel after polishing, given a Reynolds number Re* of 5530. Figure 3 In the process, the flow channel is smooth and flat overall, without obvious "bullet flow" patterns. The average surface roughness of the flow channel before polishing is about 11.2 μm, and the average surface roughness of the flow channel after polishing is about 2.4 μm.

[0088] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0089] Although this application has been described herein in conjunction with various embodiments, those skilled in the art, by reviewing the accompanying drawings, disclosure, and appended claims, will understand and implement other variations of the disclosed embodiments in carrying out the claimed application. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude a plurality. While different dependent claims may recite certain measures, this does not mean that these measures cannot be combined to produce a good effect.

[0090] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for obtaining the critical Reynolds number of a two-phase flow polishing medium, characterized in that, The two-phase flow polishing medium includes a liquid-solid two-phase flow polishing medium. The liquid phase includes water-based Newtonian fluid, water-based non-Newtonian fluid, oil-based fluid, or organic fluid. The solid phase includes abrasive particles. The two-phase flow polishing medium is used to perform surface finishing on micro-internal flow channel structures under the condition of satisfying a controllable range constituted by a Reynolds number critical value. The method includes the following steps: Obtain the flow channel diameter of the micro-internal flow channel structure, as well as the fluid viscosity, liquid phase density, abrasive particle size, and abrasive particle mass concentration of the two-phase flow polishing medium; The method for obtaining the flow velocity and abrasive grain flow state of the two-phase flow polishing medium during polishing of the micro-internal flow channel structure includes: monitoring the flow velocity of the two-phase flow polishing medium and the abrasive grain flow state during polishing of the micro-internal flow channel structure using hydrodynamic characteristic detection technology including tracer particle flow display technology and high-speed imaging technology; and measuring the flow velocity of the two-phase flow polishing medium using a Doppler ultrasonic flow meter when the flow state of the abrasive grains reaches a bullet-shaped flow state. The Reynolds number of the two-phase flow polishing medium is calculated using the channel diameter, fluid viscosity, liquid phase density, abrasive particle size, abrasive mass concentration, and flow velocity. The Reynolds number critical value of the two-phase flow polishing medium is determined by combining the flow state of the abrasive particles. The range formed by the Reynolds number critical values ​​is used as the Reynolds number control range, including: taking the Reynolds number when the liquid phase carrying the abrasive particles moves from laminar flow to turbulent flow in the micro-internal flow channel structure as the first Reynolds number critical value, taking the Reynolds number when the flow state of the abrasive particles reaches the bullet flow state as the second Reynolds number critical value, and taking the range formed by the first Reynolds number critical value and the second Reynolds number critical value as the Reynolds number control range; The Reynolds number of the two-phase flow polishing medium is calculated using the following formula: in, The Reynolds number of the two-phase flow polishing medium. The density of the liquid phase is... For flow rate, For the flow channel diameter, The abrasive grain mass concentration, For fluid viscosity, The abrasive grain size is denoted as .

2. The method for obtaining the critical Reynolds number of a two-phase flow polishing medium according to claim 1, characterized in that, The Doppler ultrasonic flow meter includes an ultrasonic transmitter, a transducer, and a Doppler non-contact flow meter, wherein... The ultrasonic transmitter is used to transmit ultrasonic signals using sonar technology, and the transmission frequency of the ultrasonic signal is <15KHz. The transducer is used to convert the ultrasonic signal into a vibration signal to drive the two-phase flow polishing medium to perform ultrasonic vibration, wherein the power density of the vibration signal is >150W / cm². 2 The amplitude is greater than 60μm; The Doppler non-contact flow meter is used to measure the flow velocity of the two-phase flow polishing medium using the Doppler effect; The flow rate accuracy error of the Doppler ultrasonic flow meter is <0.5%.

3. The method for obtaining the critical Reynolds number of a two-phase flow polishing medium according to claim 1, characterized in that, When the liquid phase is a water-based Newtonian fluid or a water-based non-Newtonian fluid, the Reynolds number control range is greater than 4000 and less than 9000. When the liquid phase is an oil-based fluid, the Reynolds number control range is greater than 5000 and less than 12000; When the liquid phase is an organic fluid, the Reynolds number control range is greater than 5000 and less than 10000.

4. The method for obtaining the critical Reynolds number of a two-phase flow polishing medium according to claim 1, characterized in that, When the micro-internal flow channel structure includes a CoCrMo alloy S-type flow channel with a flow channel diameter of 1~2.5mm and an aspect ratio of 100, and the liquid phase includes a water-based liquid phase, the density of the liquid phase is 2~20kg / cm³. 3 The two-phase flow polishing medium has a fluid viscosity of 20~120 Cp, the abrasive grains have an average particle size of 20~50 μm, the abrasive grain mass concentration is 30~80 g / L, and the two-phase flow polishing medium has a flow rate of 10~20 m / s.

5. A two-phase flow polishing method utilizing turbulence control, characterized in that, include: Under the condition of satisfying the Reynolds number control range, the micro-internal flow channel structure is polished using a liquid-solid two-phase flow polishing medium, wherein the Reynolds number control range is determined by the acquisition method described in any one of claims 1-4.

6. The two-phase flow polishing method using turbulence control according to claim 5, characterized in that, The driving pressure of the liquid-solid two-phase flow polishing medium is 0.5MPa~1.5MPa, and the polishing time is 60min~80min.

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