Tapered spiral channel type bubble generator

Abstract

This application discloses a tapered spiral channel bubble generator, comprising a first chamber, a second chamber, and a third chamber connected in sequence. The diameter of the second chamber gradually decreases along the flow direction of the medium, and spiral blades are provided on the inner wall of the second chamber. During operation, after the medium enters the second chamber, whose diameter gradually narrows along the flow direction, the continuously shrinking flow cross-sectional area induces passive acceleration of the fluid. The spiral blades with a fixed spiral angle force the medium to generate a spiral vortex. Under the synergistic effect of multiple effects such as tapered acceleration, spiral shearing, centrifugal classification, and throat cavitation, the gas mass is continuously torn apart and broken down into submicron-sized micro-nano bubbles. The mixed fluid carrying the microbubbles flows into the third chamber, whose diameter gradually expands along the flow direction. The medium flow velocity decreases, and the pressure recovers smoothly. The microbubbles avoid coalescence in the low-shear flow field and are eventually stably output to the outside.

Description

Technical Field

[0001] This application relates to the technical field of micro / nano bubble preparation, and in particular to a tapered spiral channel bubble generator. Background Technology

[0002] Micro- and nanobubble technology is a rapidly developing interdisciplinary field that has emerged in the last two decades, involving multiple disciplines such as fluid mechanics, interface science, physical chemistry, and engineering thermophysics. The diameter of micro- and nanobubbles typically ranges from tens of nanometers to tens of micrometers, much smaller than conventional bubbles (millimeters in size). This scale effect endows micro- and nanobubbles with a series of superior properties not possessed by conventional bubbles. From a physical perspective, micro- and nanobubbles possess an extremely large specific surface area. When the bubble diameter decreases from the millimeter to the micrometer scale, the specific surface area can increase by more than three orders of magnitude. This dramatic increase in specific surface area directly leads to a significant improvement in gas-liquid mass transfer rate. According to the two-film theory, the mass transfer rate is directly proportional to the interphase contact area. Experimental studies have shown that the oxygen mass transfer coefficient of micro- and nanobubbles can reach 5-10 times that of traditional aeration methods. From a kinetic perspective, micro- and nanobubbles rise very slowly in liquids. According to Stokes' law, the terminal rise velocity of a bubble is directly proportional to the square of its diameter. When the bubble diameter decreases to below 1 μm, Brownian motion becomes the dominant transport mechanism, allowing the bubbles to maintain suspension stability in the liquid phase for hours or even days without escaping. This quasi-dissolved state characteristic enables micro- and nano-bubbles to be transported with the liquid phase to distant target areas, offering irreplaceable advantages in deep aquatic oxygenation and groundwater remediation. Submicron-sized bubbles are a promising frontier in microbubble technology. However, the preparation of submicron-sized bubbles also faces greater technical challenges, as traditional bubble generation methods are difficult to economically and efficiently produce in large quantities. Summary of the Invention

[0003] The summary section introduces a series of simplified concepts, which will be further explained in detail in the detailed description section. This part of the invention is not intended to limit the key features and essential technical features of the claimed technical solution, nor is it intended to determine the scope of protection of the claimed technical solution.

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

[0005] In view of this, embodiments of this application propose a tapered spiral channel bubble generator, comprising: The first cavity, the second cavity, and the third cavity are connected in sequence; The first cavity is connected to a gas inlet pipe and a liquid inlet pipe. The diameter of the second cavity gradually decreases along the direction of medium transport, and the inner wall of the second cavity is provided with helical blades.

[0006] In one feasible implementation, the gas inlet pipe is arranged along the axial direction of the first cavity, the liquid inlet pipe is arranged along the tangential direction of the first cavity, and the first cavity is connected to the second cavity through a plurality of jet holes.

[0007] In one feasible implementation, the number of jet holes is 4 to 12, and the angle between the axial direction of the jet holes and the axial direction of the second cavity is less than or equal to 8°.

[0008] In one feasible implementation, the diameter of the jet orifice gradually increases along the transport direction of the medium, and the ratio of the diameter of the input end of the jet orifice to the diameter of the input end of the second cavity is 0.05 to 0.2.

[0009] In one feasible implementation, the helical blades are continuously arranged in the second cavity, with a fixed helical angle, and the pitch of the helical blades is proportional to the diameter of the second cavity; In one feasible implementation, the formula for determining the pitch of the helical blade is: P = πD·tan(β) Where P is the pitch, D is the diameter of the second cavity, and β is the helix angle, ranging from 10° to 45°.

[0010] In one feasible implementation, the helical blades are 6 to 15; The helical blade is connected to the second cavity, and the ratio of the gap between the helical blade and the second cavity to the diameter of the second cavity is less than or equal to 1%. The upstream end of the helical blade is streamlined or rounded, and the downstream end of the helical blade is sharp or tapered.

[0011] In one feasible implementation, the diameter of the third cavity gradually increases along the direction of medium transport.

[0012] In one feasible implementation, the ratio of the axial length of the first cavity to the diameter of the input end of the second cavity is 1 to 3.

[0013] In one feasible implementation, the ratio of the diameter of the input end of the second cavity to the diameter of the output end of the second cavity is 1.5 to 3.0. The ratio of the axial length of the second cavity to the diameter of the input end of the second cavity is 2 to 5.

[0014] Compared with the prior art, the present invention has at least the following beneficial effects: The tapered spiral channel bubble generator provided in this application includes a first chamber, a second chamber, and a third chamber connected in sequence. The diameter of the second chamber gradually decreases along the transport direction of the medium. The inner wall of the second chamber is provided with spiral blades. During operation, the gas and liquid two-phase mediums are introduced into the first chamber through the gas inlet pipe and the liquid inlet pipe, respectively. The liquid forms a swirling flow inside the first chamber, and multiple jets are ejected at high speed from the jet holes of the first chamber. The gas and liquid are initially mixed by jet entrainment and turbulence, forming a gas-liquid two-phase mixture, which is then transported to the second chamber. After the medium enters the second chamber, whose diameter gradually narrows along the flow direction, the continuous reduction in the flow cross-sectional area causes passive acceleration of the fluid. The spiral blades with a fixed spiral angle force the medium to generate a spiral swirling flow. Under the synergistic effect of tapered acceleration, spiral shearing, centrifugal classification, and throat cavitation, the gas mass is continuously torn apart, broken up, and refined into submicron-sized micro-nano bubbles. The mixed fluid carrying microbubbles flows into the third chamber, and the diameter of the third chamber gradually expands along the flow direction. The medium velocity decreases and the pressure recovers slowly. The microbubbles avoid coalescence in the low shear flow field and are eventually stably output to the outside.

[0015] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0016] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 A schematic structural diagram of a tapered spiral channel bubble generator according to an embodiment of this application.

[0017] in, Figure 1 The correspondence between the reference numerals and component names in the attached drawings is as follows: 110 First cavity, 120 Second cavity, 130 Third cavity, 140 Spiral blade, 150 Jet orifice; 111 Gas inlet pipe, 112 Liquid inlet pipe. Detailed Implementation

[0018] The following description provides numerous specific details to offer a more thorough understanding of the technical solutions provided by this invention. However, it will be apparent to those skilled in the art that the technical solutions provided by this invention can be implemented without one or more of these details.

[0019] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of the stated features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or combinations thereof.

[0020] Exemplary embodiments according to the present invention will now be described in more detail with reference to the accompanying drawings. However, these exemplary embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. It should be understood that these embodiments are provided so that the disclosure of the invention is thorough and complete, and that the concept of these exemplary embodiments is fully conveyed to those skilled in the art.

[0021] like Figure 1 As shown in the figure, this application proposes a tapered spiral channel bubble generator, including: a first cavity 110, a second cavity 120 and a third cavity 130 connected in sequence; wherein, the first cavity 110 is connected to a gas inlet pipe 111 and a liquid inlet pipe 112; wherein, the diameter of the second cavity 120 gradually decreases along the conveying direction of the medium, and the inner wall of the second cavity 120 is provided with spiral blades 140.

[0022] like Figure 1As shown, the tapered spiral channel bubble generator provided in this application embodiment includes a first cavity 110, a second cavity 120, and a third cavity 130 connected in sequence. The diameter of the second cavity 120 gradually decreases along the conveying direction of the medium. The inner wall of the second cavity 120 is provided with spiral blades 140. During operation, the gas and liquid two-phase mediums are introduced into the first cavity 110 through the gas inlet pipe 111 and the liquid inlet pipe 112, respectively. The liquid forms a swirling flow inside the first cavity 110, and multiple jets are ejected at high speed from the jet holes 150 of the first cavity 110. The gas and liquid are initially mixed by jet entrainment and turbulence, forming a gas-liquid two-phase mixture and conveying it to the second cavity 120. After the medium enters the second cavity 120, whose diameter gradually narrows along the flow direction, the continuously shrinking flow cross-sectional area induces passive acceleration of the fluid. The fixed helical blades 140 force the medium to generate a helical vortex. Under the synergistic effect of multiple effects such as gradual acceleration, helical shearing, centrifugal classification, and throat cavitation, the gas mass is continuously torn apart and broken down into submicron-sized micro- and nano-bubbles. The mixed fluid carrying the microbubbles flows into the third cavity 130, whose diameter gradually expands along the flow direction. The medium velocity decreases, the pressure recovers smoothly, and the microbubbles avoid coalescence in the low-shear flow field, eventually stabilizing and being output outward.

[0023] The gradually narrowing spiral channel bubble generator provided in this application embodiment has a first chamber 110 that relies on tangential liquid inlet swirling flow and multiple sets of jet holes 150 to form a high-speed jet, which enhances the initial dispersion effect of gas and liquid, greatly improves the premixing uniformity, and avoids large gas clumps directly entering the second chamber 120 to reduce the crushing efficiency; the second chamber 120 has a gradually narrowing structure, and the gas-liquid two-phase mixture simultaneously undergoes passive acceleration, forced swirling flow, centrifugal classification and cavitation crushing processes in the gradually narrowing spiral channel, so as to achieve efficient refinement of bubbles to the submicron level. It can achieve passive acceleration of fluid without external energy consumption. With a fixed helix angle of 140° helical blades, the pitch naturally decreases with the channel diameter, eliminating the need for complex variable pitch machining and reducing manufacturing costs. Multiple coupling effects significantly improve Weber number and cavitation intensity, stably producing submicron bubbles below 1μm, with a gas-liquid mass transfer coefficient far higher than traditional aeration equipment. Finally, the 130° gradually expanding structure of the third chamber achieves medium pressure stabilization and deceleration, eliminates flow backflow and strong shear, inhibits micro-nano bubble collision and aggregation, and prolongs the suspension time of bubbles in water. The equipment is adaptable to various gas-liquid systems, has a wide applicable flow range, and significantly improves overall energy utilization.

[0024] The tapered spiral channel bubble generator provided in this application is used to solve the technical problems of insufficient bubble refinement ability, low energy utilization rate, and difficulty in achieving efficient preparation of submicron-sized bubbles in existing constant cross-section swirl cavitation technology.

[0025] The tapered spiral channel bubble generator provided in this application adopts a three-section cavity structure design: a first cavity 110 (swirling-jet coupling cavity), a second cavity 120 (tapered spiral channel cavity), and a third cavity 130 (tapered expanding stable output cavity), achieving efficient mixing of gas and liquid phases, strong bubble fragmentation and refinement, and stable output of the gas-liquid mixture. The second cavity 120 adopts a tapered channel design, with spiral blades 140 having a fixed spiral angle inside. The passive acceleration effect of the tapered channel and the forced swirling effect of the spiral blades 140 synergistically enhance the gas-liquid shear and cavitation intensity, enabling the bubble diameter to reach submicron levels below 1 μm.

[0026] Another objective of the tapered spiral channel bubble generator provided in this application is to offer a micro / nano bubble generating device that is simple in structure, easy to process, low in manufacturing cost, low in energy consumption, and high in energy utilization. This invention employs a fixed spiral angle, significantly simplifying the manufacturing process of the spiral blade 140° and reducing production costs.

[0027] Another objective of the tapered spiral channel bubble generator provided in this application is to provide a micro-nano bubble generating device that is applicable to a wide range of flow rates, is flexible in operation, and can be used in various gas-liquid systems (air-water, oxygen-water, ozone-water, carbon dioxide-water, etc.), so as to meet the needs of different industrial fields for large-scale preparation of submicron-level bubbles.

[0028] The tapered spiral channel bubble generator provided in this application operates as follows: gas is introduced into the first chamber 110 through the gas inlet pipe 111. After the liquid forms an initial swirling flow within the first chamber 110, it is accelerated through the jet orifice 150 to form a high-speed liquid jet. According to Bernoulli's equation, the relationship between the jet velocity vj and the pressure difference Δp before and after the jet orifice 150 is: ,in Fluid density, kg / m³ 3 After exiting the jet orifice 150, the high-speed liquid jet enters the downstream space of the first cavity 110, where it encounters the gas introduced by the gas inlet pipe 111. Under the action of jet entrainment effect and turbulent pulsation, the gas is torn into larger-scale gas clusters or filaments by the high-speed liquid jet. The initial size of the gas clusters or filaments depends on factors such as jet velocity, gas-liquid flow ratio, and interfacial tension. The initially dispersed gas-liquid two-phase mixture flows out of the first cavity 110 and enters the second cavity 120 for further refinement and breakup.

[0029] like Figure 1 As shown, in one feasible embodiment, the gas inlet pipe 111 is arranged along the axial direction of the first cavity 110, the liquid inlet pipe 112 is arranged along the tangential direction of the first cavity 110, and the first cavity 110 is connected to the second cavity 120 through a plurality of jet holes 150.

[0030] In this technical solution, a layout of gas inlet pipe 111 and liquid inlet pipe 112 is further provided. The axial gas inlet pipe 111 can smoothly introduce the gas phase, so that the liquid enters the first cavity 110 under pressure and forms a preliminary swirling flow field around the axis in the first cavity 110. With the help of multiple sets of jet holes 150, the mixed fluid is injected into the second cavity 120 at high speed. The gas phase is fully broken up by jet entrainment and turbulent tearing, realizing efficient gas-liquid premixing. This avoids large gas masses from directly entering the second cavity 120, reduces the processing load of the core crushing section, improves the uniformity of bubble refinement, optimizes the flow distribution in the cavity, reduces local resistance loss, and improves the overall energy utilization efficiency of the device.

[0031] like Figure 1 As shown, in one feasible embodiment, the number of jet holes 150 is 4 to 12, preferably 6 to 8. The angle between the axial direction of the jet holes 150 and the axial direction of the second cavity 120 is less than or equal to 8°, so that the liquid is accelerated through the jet holes 150 and ejected axially to form multiple uniformly distributed high-speed liquid jets.

[0032] This technical solution further provides the arrangement parameters of the jet orifices 150. The number of jet orifices 150 is limited to 4 to 12, which can form multiple uniformly distributed high-speed liquid jets, expand the gas-liquid contact range, and improve the premixing uniformity. The axial angle between the jet orifices 150 and the second cavity 120 is ≤8°, which can ensure that the jets are delivered into the second cavity 120 along the near-axial direction, reducing the impact loss and backflow caused by the radial displacement of the fluid. The simultaneous tearing of the gas phase by multiple jets avoids the accumulation of local gas clusters, reduces the crushing pressure of the second cavity 120, and at the same time reduces the flow resistance, reduces ineffective energy consumption, improves the overall cavitation crushing efficiency, and ensures the stable quality of subsequent submicron bubble generation.

[0033] like Figure 1 As shown, in one feasible embodiment, the diameter of the jet orifice 150 gradually increases along the medium conveying direction, and the ratio of the diameter of the input end of the jet orifice 150 to the diameter of the input end of the second cavity 120 is 0.05 to 0.2.

[0034] In this technical solution, the arrangement parameters of the jet orifice 150 are further provided. The jet orifice 150 adopts a gradually expanding structure along the flow direction, which can reduce the jet outflow resistance and reduce energy loss. The ratio of the input end diameter to the inlet diameter of the second cavity 120 is controlled at 0.05~0.2, which can ensure that the jet forms a sufficiently high speed to tear the gas phase and avoid the jet velocity being insufficient and the gas-liquid premixing effect being poor due to an excessively large ratio. It can also prevent the pipeline resistance from surging and energy consumption from rising due to an excessively small ratio, thus balancing the flow rate and shear strength and providing a high-quality gas-liquid mixing precursor fluid for the efficient refinement of bubbles in the second cavity 120.

[0035] Understandably, when the ratio of the diameter of the input end of the jet orifice 150 to the diameter of the input end of the second cavity 120 is less than 0.05, the flow resistance is too high, resulting in a significant increase in system energy consumption; when the ratio of the diameter of the input end of the jet orifice 150 to the diameter of the input end of the second cavity 120 is greater than 0.2, the jet velocity is too low, the shear strength of the initial gas-liquid mixture is insufficient, and the gas cannot be effectively torn apart and dispersed.

[0036] like Figure 1 As shown, in one feasible embodiment, in the second cavity 120, the helical blades 140 are continuously arranged with a fixed helical angle, and the pitch of the helical blades 140 is proportional to the diameter of the second cavity 120.

[0037] This technical solution further provides an arrangement of the helical blades 140. The continuous arrangement of the helical blades 140 can constrain the fluid movement throughout the entire process, ensuring that the gas-liquid mixture maintains a stable and complete helical swirling flow field within the second cavity 120, avoiding flow field turbulence and local gas phase accumulation. A fixed helical angle design is adopted, relying on the characteristic that the pitch is proportional to the diameter of the second cavity 120. As the channel diameter contracts along the flow direction, the pitch automatically and synchronously decreases, eliminating the need for more complex variable-pitch blades, significantly simplifying the processing technology and reducing manufacturing costs. The reduced pitch in the downstream region increases the blade's guiding density, prolonging the duration of bubble shearing, and fully enhancing the synergistic crushing effect of gradual acceleration, helical shearing, and centrifugal cavitation, stably producing submicron-sized bubbles. Without increasing energy consumption, this significantly improves the bubble refinement uniformity and the overall energy utilization efficiency of the equipment.

[0038] like Figure 1 As shown, in one feasible implementation, the formula for determining the pitch of the helical blade 140 is: P = πD·tan(β) Wherein, P is the pitch, D is the diameter of the second cavity 120, and β is the helix angle, which ranges from 10° to 45°, preferably from 20° to 35°.

[0039] This technical solution further provides a specific calculation method for the pitch of the helical blade 140, fixing the helical angle β within the range of 10° to 45°. The pitch is linearly matched to the diameter of the second cavity 120, eliminating the need for separately designed variable-pitch blades and significantly simplifying modeling and manufacturing processes. As the diameter of the second cavity 120 decreases, the pitch automatically narrows synchronously, increasing downstream flow density and continuously enhancing the fluid's helical shearing and centrifugal cavitation effects. A fixed helical angle allows for stable control of the swirling intensity, avoiding insufficient axial flow velocity due to an excessively large angle or weak shearing due to an excessively small angle. This balances bubble breakage efficiency with fluid flow resistance, resulting in the stable production of submicron bubbles with uniform particle size.

[0040] It is understandable that when the helix angle is greater than 45°, the circumferential component of the helical flow may be insufficient, the swirling intensity may be weak, and the centrifugal classification effect and interfacial shear effect may be limited. When the helix angle is less than 10°, the proportion of axial velocity converted into tangential velocity may be too high, the axial propulsion capacity may be insufficient, and the flow channel resistance may increase significantly.

[0041] Understandably, the spiral blade 140 can decrease naturally. On the one hand, the blade guide density increases in the downstream region, and the contact and mixing of the gas and liquid phases are more complete. On the other hand, the local wrap angle of the spiral blade 140 in the downstream region increases, and the action time of the bubbles on the blade guide surface is prolonged, resulting in more thorough breakup.

[0042] Understandably, the helical blade 140 is integrally formed onto the inner wall of the tapered channel of the second cavity 120 via (3D printing, welding, or any related process). The root of the helical blade 140 is smoothly connected to the wall surface, and the blade tip points towards the central axis of the channel. The helical blade 140 extends radially inward. A helical flow channel gap is formed between adjacent helical blades 140, through which the gas-liquid two-phase mixture passes.

[0043] like Figure 1 As shown, in one feasible embodiment, the helical blade 140 has 6 to 15 blades, preferably 8 to 10 blades; the helical blade 140 is connected to the second cavity 120, and the ratio of the gap between the helical blade 140 and the second cavity 120 to the diameter of the second cavity 120 is less than or equal to 1%; the upstream end of the helical blade 140 is streamlined or rounded, and the downstream end of the helical blade 140 is sharp or tapered.

[0044] This technical solution further provides the arrangement quantity and structural parameters of the helical blades 140. The number of helical blades 140 is 6 to 15, preferably 8 to 10, which can form a multi-layered uniform guiding vortex, fully segment the gas-liquid mixture, and increase the shear contact frequency. Too few blades will result in blank flow field and gas cloud escape, while too many blades will increase fluid resistance and energy consumption. The diameter ratio of the gap between the blades and the second cavity 120 is ≤1%, which can prevent the fluid from short-circuiting through the wall gaps and force all the medium to pass through the helical flow channel of the blades, ensuring sufficient cavitation and fragmentation. The upstream end adopts a streamlined / rounded corner structure, which can reduce fluid impact loss and reduce eddies and pressure loss; the downstream end is set with a sharp, gradually thinning shape, which can enhance the fluid stripping and tearing effect and intensify the gas-liquid interface instability and fragmentation. The overall structural combination can simultaneously reduce frictional resistance, eliminate fluid bypass, and enhance the bubble shearing and pulverizing effect, improve the fineness and uniformity of micro-nano bubbles while controlling energy consumption, prolong the cavitation duration, and optimize the mass transfer performance of the device.

[0045] It is understandable that when the number of spiral blades (n) is less than 6, the spiral guiding effect is insufficient and the swirling intensity is low; when n is greater than 15, the blades block the flow channel too much, the flow resistance increases sharply, and the energy consumption is too high.

[0046] In some examples, the helical blade 140 has an airfoil of uniform or variable thickness twisted blade, with the outer edge of the blade fitting against or maintaining a small gap (not exceeding 1% of the channel diameter) with the inner wall of the tapering channel, and the inner edge of the blade connected to or integrally formed with the central hub. The leading edge (upstream end) of the blade adopts a streamlined or rounded design to reduce inlet impact loss; the trailing edge (downstream end) of the blade adopts a sharp or tapered design to reduce wake loss.

[0047] It is understood that in the tapered spiral channel bubble generator provided in this application embodiment, the second cavity 120 can coexist, and the synergistic effect of four physical effects jointly promotes the efficient refinement of bubbles to the submicron level: (1) Gradual acceleration effect like Figure 1 As shown, according to the law of conservation of mass (continuity equation), the axial velocity v of the gas-liquid mixture in the converging channel... a It increases as the flow cross-sectional area decreases. The flow cross-sectional area A of the tapered channel is A = πD² / 4 (without a central hub structure, the cross-sectional area occupied by the blades is relatively small and can be ignored or included as a correction factor; D is the diameter). Therefore, the axial velocity v at the outlet of the second cavity 120 is... a2 With the axial velocity v at the inlet a1 The ratio is:

[0048] Among them, v a2 v is the axial velocity at the outlet of the second cavity 120. a1 The axial velocity at the inlet of the second cavity 120, where D1 is the diameter at the inlet of the second cavity 120, and D2 is the diameter at the inlet of the second cavity 120. Since D1 > D2, the ratio is always greater than 1, indicating that the fluid undergoes passive acceleration in the converging channel. For example, when D1 / D2 = 2.0, That is, the axial velocity at the exit is approximately 3.8 times that at the inlet. When D1 / D2 = 2.5, This means that the axial velocity at the exit is approximately 6.25 times that at the inlet. This acceleration effect is entirely determined by the channel geometry and requires no additional external energy input, which is the core energy-saving advantage of the tapered channel.

[0049] (2) Helical shear effect The helical blades 140 exert a circumferential guiding effect on the fluid, causing it to undergo helical motion within the narrowing channel. The trajectory of the fluid particles is a helix that rotates around the axis while simultaneously advancing axially. Under a fixed helix angle β, the axial velocity v... a With tangential velocity v t The following relationship must be satisfied:

[0050] Among them, v a v is the axial velocity. t This represents the tangential velocity.

[0051] Because of v a v gradually increases along the axial direction t The pressure also increases accordingly. The gas and liquid phases experience intense shearing on the guide surface of the spiral blade 140. The bubbles are stretched and deformed in the shear flow field. When the inertial force acting on the bubbles (caused by shear) exceeds the constraint of the interfacial tension, the bubbles break up.

[0052] The stability of a bubble in a shear flow field is determined by the Weber number We:

[0053] Where We is the Weiber number, ρ l v is the density of the liquid. rel Let d be the relative velocity between the gas and liquid. b Let be the bubble diameter, and σ be the gas-liquid interfacial tension. The critical value of the Weber number is approximately 1-2; when the actual Weber number exceeds this critical value, the bubble breaks up. As the fluid accelerates, v... rel As the diameter increases, the We number increases, and the bubbles become more easily broken. When the taper ratio D1 / D2 = 2.0 and the helix angle β = 30°, the We number at the outlet can reach more than 10 times that at the inlet.

[0054] (3) Centrifugal grading effect In a rotating flow field, the gas and liquid phases react due to the density difference ρ l Much greater than ρ g The gas phases are subjected to different centrifugal forces due to their varying density. Under the influence of a larger centrifugal force, the liquid phase is thrown outwards (towards the channel wall), while the gas phase accumulates in the central low-pressure area, forming a slender central gas core. The radius of the central gas core depends on the gas-liquid flow ratio and the rotation intensity.

[0055] Intense gas-liquid interfacial shear is formed between the central gas core and the rapidly rotating liquid phase. Interfacial instability (Kelvin-Helmholtz instability) causes fluctuations, wrinkles, tears, and detachment on the gas core surface, forming numerous microbubbles. The detached bubbles are then entrained into the surrounding high-shear liquid phase, undergoing further stretching and breakup.

[0056] The radial pressure gradient in the centrifugal force field is:

[0057] in, For radial pressure gradient, ρ m Let be the density of the gas-liquid mixture, and r be the radial coordinate. With the tangential velocity v... t As the axial direction increases, the radial pressure gradient also increases, the centrifugal classification effect intensifies, the stability of the gas core decreases, and the interface detachment becomes more severe. In the exit region of the converging channel, all three effects (converging acceleration, helical shearing, and centrifugal classification) reach their strongest simultaneously, forming a highly efficient bubble breakup zone that enables bubbles to reach submicron scale.

[0058] (4) Jet cavitation effect Given that the throat diameter is d, the orifice length is l, the throat outlet diameter is d, the throat inlet diameter is D, the pressure in the throat negative pressure zone is P2, the inlet pressure is P1, the outlet pressure is atmospheric pressure P0; the flow velocity at the throttling orifice is V2, the flow velocities at the outlet and inlet are V1, and the flow rate in the pipe is Q.

[0059] According to the orifice throttling equation: in, C v This is the orifice velocity coefficient. Since dissolved oxygen in the water is only released when the negative pressure P2 at the throat of the injection device is lower than the oxygen separation pressure of -98957.2 Pa, the various dimensional parameters of the equipment can be obtained using Bernoulli's equation. With a flow rate of Q=10m in the injection pipe 3 Taking d=9mm and D=40mm as an example, the throat pressure P2 can be calculated as -1.03MPa, which is lower than the oxygen separation pressure, thus preliminarily proving that the throat structure design meets the requirements.

[0060] In one feasible implementation, the diameter of the third cavity 130 gradually increases along the direction of medium transport.

[0061] In this technical solution, the style of the third cavity 130 is further provided. The third cavity 130 with a gradually increasing diameter along the medium transportation direction forms a gradually expanding pressure stabilizing flow channel. The gas-liquid mixture refined by the second cavity 120 decelerates and stabilizes in the gradually expanding channel, the pressure gradually recovers, and the microbubbles remain stable in a lower shear environment without coalescing, and finally are discharged from the outlet. After the mixed fluid carrying the microbubbles enters, the flow velocity decreases gently, and the shear strength of the flow field weakens synchronously, avoiding the secondary collision and coalescence of micro-nano bubbles caused by high-speed and strong shear; the pressure in the cavity slowly rises, eliminating the turbulent vortex caused by the sudden change of negative pressure at the outlet of the second cavity 120, and reducing the bubble collapse loss. At the same time, the gradually expanding structure smoothly guides the fluid, reduces the resistance at the pipeline outlet, realizes the stable output of submicron bubble liquid with uniform particle size, effectively prolongs the suspension retention time of microbubbles in the liquid phase, and improves the overall gas-liquid mass transfer effect.

[0062] In some examples, the third cavity 130 is a gradually expanding channel structure. The diameter of the inlet of the channel third cavity 130 is D2 (the same as the outlet diameter of the second cavity 120), the outlet diameter is D3, and D2 < D3. The gradually expanding angle δ of the gradually expanding channel is 5° to 15°, preferably 6° to 10°. The ratio L3 / D2 of the axial length L3 of the channel to the outlet diameter D2 of the second cavity 120 is 1 to 4, preferably 1.5 to 3.

[0063] It can be understood that the definition of the gradually expanding angle δ is twice the angle (full angle) between the generatrix of the gradually expanding channel wall and the axis, or the angle (half angle) between the generatrix of the wall and the axis. The full angle definition is adopted in this invention. When δ is less than 5°, the gradual expansion is too gentle, the pressure recovery is slow, and the axial length of the device is too large; when δ is greater than 15°, the gradual expansion is too sharp, the flow may undergo boundary layer separation, generating a recirculation zone, which is not conducive to the stability of microbubbles.

[0064] The inlet diameter D2 and the outlet diameter D3 of the third cavity 130 satisfy the following relationship: the ratio D2 / D3 of the inlet diameter D2 to the outlet diameter D3 is 0.8 - 1.5. When D2 / D3 is greater than 1.5, the gradually expanding angle is too large and the flow is unstable; when D2 / D3 is less than 0.8, the degree of gradual expansion is insufficient and the pressure recovery effect is limited.

[0065] The tapered spiral channel bubble generator provided in this embodiment has a first chamber 110, a second chamber 120, and a third chamber 130 arranged coaxially in series, with the axes of the three chambers coinciding. The outlet end of the first chamber 110 is connected to the inlet end of the second chamber 120, and the outlet end of the second chamber 120 is connected to the inlet end of the third chamber 130. The connection points can be sealed and fixed using flange connections, threaded connections, or welding to ensure the sealing and coaxiality of the connection. The above proportional relationship ensures the flow matching and functional coordination among the three chambers. The first chamber 110 provides sufficient gas-liquid premixing time, the second chamber 120 provides sufficient bubble refinement path length, and the third chamber 130 provides an appropriate deceleration and stabilization distance. The three chambers are connected sequentially, allowing the gas and liquid phases to successively undergo three stages: premixing, strong shear refinement, and stable output, forming a complete bubble generation process chain.

[0066] like Figure 1 As shown, in one feasible embodiment, the ratio of the axial length of the first cavity 110 to the diameter of the input end of the second cavity 120 is 1 to 3, preferably 1.5 to 2.5.

[0067] In this technical solution, the ratio of the axial length of the first chamber 110 to the diameter of the input end of the second chamber 120 is limited to 1 to 3. This allows for sufficient space for swirling mixing, ensuring thorough contact and mixing of gas and liquid within the swirling field formed by tangential liquid inlet. A ratio that is too small will result in insufficient premixing stroke, causing large gas clumps to flow into the second chamber 120 without being broken up, thus reducing crushing efficiency. A ratio that is too large will increase fluid friction resistance and energy consumption. This dimensional ratio balances the premixing effect and flow loss, ensuring uniform gas-liquid dispersion of the fluid output through the jet orifice 150, reducing the bubble crushing load in the second chamber 120, and improving overall cavitation refinement stability.

[0068] It is understandable that if the ratio of the axial length of the first cavity 110 to the diameter of the input end of the second cavity 120 is too small, the swirl development will be insufficient and the gas-liquid premixing effect will be poor; if it is too large, it will increase unnecessary pressure drop losses along the path and reduce the system energy utilization rate.

[0069] like Figure 1 As shown, in one feasible embodiment, the ratio of the diameter of the input end of the second cavity 120 to the diameter of the output end of the second cavity 120 is 1.5 to 3.0, preferably 2.0 to 2.5; the ratio of the axial length of the second cavity 120 to the diameter of the input end of the second cavity 120 is 2 to 5, preferably 2.5 to 4.

[0070] In this technical solution, the structural parameters of the second chamber 120 are further provided. The ratio of the inlet and outlet diameters of the second chamber 120 is 1.5 to 3.0, which can form a reasonable tapering amplitude, allowing the fluid to accelerate smoothly and continuously, generating sufficient negative pressure to achieve cavitation and gas release. If the ratio is too small, the acceleration and cavitation intensity will be insufficient; if it is too large, the flow resistance will increase dramatically. The ratio of axial length to inlet diameter is 2 to 5 to ensure that the fluid has sufficient breaking stroke within the spiral blades 140, fully completing shearing and centrifugal refinement. The two sets of dimensional parameters are matched with each other, taking into account the fluid acceleration amplitude, cavitation duration, and flow resistance, effectively improving the degree of bubble breakage, stably preparing submicron bubbles, and balancing the refinement performance and energy consumption level of the device.

[0071] Understandably, when the ratio of the diameter of the input end of the second cavity 120 to the diameter of the output end of the second cavity 120 is less than 1.5, the cavitation is insufficient, the passive acceleration effect is limited, and the bubble refinement ability is not strong. When the ratio of the diameter of the input end of the second cavity 120 to the diameter of the output end of the second cavity 120 is greater than 3.0, the cavitation is too large, the flow velocity at the channel outlet is too high, which may cause excessive cavitation development, leading to bubble coalescence and flow instability.

[0072] It is understood that the tapered spiral channel bubble generator provided in this application embodiment can be widely used in the following technical scenarios: uranium leaching gas injection operations, gas-liquid mass transfer enhancement in chemical reactors, advanced oxidation treatment of industrial wastewater and domestic sewage, dissolved oxygenation of agricultural irrigation water, bottom oxygenation in high-density aquaculture, in-situ chemical oxidation remediation of groundwater, air flotation oil removal from oilfield produced water, and preparation of functional bubble liquids in the food, beverage, and pharmaceutical fields, as well as other industrial and civilian fields that require a large number of submicron-sized micro-nano bubbles.

[0073] In this invention, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more unless otherwise explicitly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "link" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0074] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0075] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present 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.

[0076] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A gradually narrowing spiral channel bubble generator, characterized in that, include: The first cavity, the second cavity, and the third cavity are connected in sequence; The first cavity is connected to a gas inlet pipe and a liquid inlet pipe. The diameter of the second cavity gradually decreases along the direction of medium transport, and the inner wall of the second cavity is provided with helical blades.

2. The gradually narrowing spiral channel bubble generator according to claim 1, characterized in that, The gas inlet pipe is arranged along the axial direction of the first cavity, and the liquid inlet pipe is arranged along the tangential direction of the first cavity. The first cavity is connected to the second cavity through a plurality of jet holes.

3. The gradually narrowing spiral channel bubble generator according to claim 2, characterized in that, The number of jet holes is 4 to 12, and the angle between the axial direction of the jet holes and the axial direction of the second cavity is less than or equal to 8°.

4. The tapered spiral channel bubble generator according to claim 3, The diameter of the jet orifice gradually increases along the direction of medium transport, and the ratio of the diameter of the input end of the jet orifice to the diameter of the input end of the second cavity is 0.05 to 0.

2.

5. The gradually narrowing spiral channel bubble generator according to claim 1, characterized in that, In the second cavity, the helical blades are continuously arranged with a fixed helical angle, and the pitch of the helical blades is proportional to the diameter of the second cavity.

6. The tapered spiral channel bubble generator of claim 5, wherein, The formula for determining the pitch of the helical blade is: P = πD·tan(β) Where P is the pitch, D is the diameter of the second cavity, and β is the helix angle, ranging from 10° to 45°.

7. The tapered spiral channel bubble generator according to claim 6, characterized in that, The spiral blades consist of 6 to 15 blades; The helical blade is connected to the second cavity, and the ratio of the gap between the helical blade and the second cavity to the diameter of the second cavity is less than or equal to 1%. The upstream end of the helical blade is streamlined or rounded, and the downstream end of the helical blade is sharp or tapered.

8. The gradually narrowing spiral channel bubble generator according to any one of claims 1 to 6, characterized in that, The diameter of the third cavity gradually increases along the direction of medium transport.

9. The tapered spiral channel bubble generator according to any one of claims 1 to 6, characterized in that, The ratio of the axial length of the first cavity to the diameter of the input end of the second cavity is between 1 and 3.

10. The tapered spiral channel bubble generator according to any one of claims 1 to 6, characterized in that, The ratio of the diameter of the input end of the second cavity to the diameter of the output end of the second cavity is 1.5 to 3.0; The ratio of the axial length of the second cavity to the diameter of the input end of the second cavity is 2 to 5.

Images