A venturi type micro-nano bubble generator based on adjustable multi-channel parallel connection

Abstract

The utility model discloses a kind of Venturi tube type micro-nano bubble generators based on adjustable multi-channel parallel, Venturi tube includes front section and rear end, wherein, front section includes inlet section, multiple contraction sections of parallel arrangement, multiple throat sections of parallel arrangement, which are coaxially arranged in turn along water flow direction, contraction section and throat section are equipped with outer ring, rear section includes multiple throat pipe sections of parallel arrangement, multiple expansion sections of parallel arrangement and outlet section, which are coaxially arranged in turn along water flow direction, throat pipe section and expansion section are equipped with outer ring, corresponding contraction section, throat section, throat pipe section, expansion section form an independent Venturi tube channel;The front section and rear section of Venturi tube form air cavity by the outer ring of each other. The utility model effectively avoids the design defect of micro-bubble generator design in the prior art, solves the technical problems of large average particle size of bubble formation, uneven bubble distribution, low bubble formation efficiency, easy to block injection inlet, incomplete liquid atomization, difficult installation and maintenance, excessive energy consumption, low bubble overflow efficiency.

Description

Technical Field

[0001] This utility model relates to the field of wastewater purification and liquid atomization technology, specifically to a venturi tube micro / nano bubble generator based on adjustable multi-channel parallel connection. Background Technology

[0002] Micro- and nanobubbles possess characteristics such as large specific surface area, strong adhesion, high mass transfer efficiency, surface charge, and a large number of hydroxyl radicals. They are currently widely used in chemical reaction processes, mineral flotation, pollution control, ecological restoration, aquaculture, fruit and vegetable cleaning, and hydroponics. Specialized equipment for generating micro- and nanobubbles is commonly referred to as a micro- and nanobubble generator, which can be classified according to its working mechanism into types such as dissolved gas release, gas-entraining dispersion, microporous gas dispersion, and swirling shearing. Generating high-quality and sufficient quantities of micro- and nanobubbles and ensuring their complete separation are prerequisites and guarantees for achieving the aforementioned engineering applications.

[0003] In the field of liquid atomization, the micro-nano size, density, and uniformity of bubbles in the gas-liquid two-phase mixing process are the key factors that determine the atomization effect. High-viscosity liquids can easily cause blockages in narrow pipes, and solving the problem of smooth injection of high-viscosity liquids is the fundamental requirement for achieving atomization. For example, patents such as ZL202110559011.3 (a high-temperature oily wastewater flotation bubble cutting device), ZL201910048816.4 (a multi-stage swirling microbubble releaser and dissolved gas release system), ZL202011338828.X (a swirling micro / nano bubble generator), ZL201820826891.X (a swirling aerator), ZL202010092827.5 (a swirling aerator), CN219588936U (a bubble atomizing nozzle based on multi-channel series Venturi tubes), etc., all aim to improve the structure of microbubble generators and solve existing problems.

[0004] In summary, improvements have been made to address the shortcomings of conventional swirling shear microbubble generators and traditional Venturi tube microbubble generators, resulting in some improvements in bubble quality. However, problems remain, including large average bubble size, uneven distribution, high energy consumption, insufficient gas-liquid separation, easy clogging of the injection port by high-viscosity liquids, and difficult installation and maintenance. Therefore, large bubble size, uneven distribution, low bubble overflow efficiency, and easy clogging of the injection port are the core issues in bubble formation of Venturi tube microbubble generators. Improving the design of technical parameters such as the air inlet structure, inlet position, air inlet angle, diffusion angle, swirling shear of the liquid outlet, and pressure reduction delay, as well as the injection port structure, addressing the clogging issue, and improving the swirl structure and flow channel structure to enhance bubble breaking effect, thereby reducing bubble size, improving gas-liquid mixing, increasing bubble dispersion uniformity, achieving high bubble quality and efficiency, and reducing operating energy consumption are urgent technical problems to be solved by those skilled in the art. In view of this, a venturi tube-type micro / nano bubble generator based on adjustable multi-channel parallel connection is proposed. Utility Model Content

[0005] The technical problem to be solved by this utility model is to overcome the existing defects and provide a venturi tube-type micro-nano bubble generator based on adjustable multi-channel parallel connection, so as to solve the technical problems of the current micro bubble generator design defects, such as large average bubble size, uneven bubble distribution, low bubble formation efficiency, easy blockage of injection port, difficult installation and maintenance, excessive energy consumption, and insufficient gas-liquid separation.

[0006] To achieve the above objectives, this utility model provides the following technical solution: An adjustable multi-channel parallel Venturi tube micro / nano bubble generator includes a Venturi tube and an air intake unit. The Venturi tube includes a front section and a rear section. The front section includes an inlet section, multiple converging sections, and multiple throat sections arranged in parallel, all arranged coaxially along the water flow direction. The converging sections and throat sections are provided with outer rings. The rear section includes multiple throat sections, multiple expanding sections, and an outlet section arranged in parallel, all arranged coaxially along the water flow direction. The throat sections and expanding sections are provided with outer rings. The corresponding converging sections, throat sections, and expanding sections form an independent Venturi tube channel. The air intake unit is located at the tail end of the front or rear section of the Venturi tube.

[0007] Furthermore, the internal channel of the contraction segment is a continuously contracting conical structure, with a rounded transition between the contraction segment and the throat segment; the internal channel of the expansion segment is a continuously expanding conical structure, with a rounded transition between the expansion segment and the throat segment.

[0008] Furthermore, the ratio of the sum of the inner diameter cross-sectional areas of the throat segment and the larynx segment to the inner diameter cross-sectional area of ​​the inlet segment is 0.05-0.1, and the ratio of the sum of the lengths of the throat segment and the larynx segment to their inner diameter is 1.5-3.

[0009] Furthermore, the contraction angle of the contraction segment is 30° to 120°, and the expansion angle of the expansion segment is 30° to 120°.

[0010] Furthermore, the parallel throat segment and throat tube segment are respectively connected to the convex and concave parts of the corresponding contraction segment and expansion segment conical structure, and the taper of the convex and concave surfaces is consistent, with an angle of 60°-90°.

[0011] Furthermore, the intake unit includes an intake chamber, an intake gap, and an intake pipe. The front and rear sections of the venturi tube form the intake chamber through their respective outer rings. An intake gap is provided at the connection between the throat section and the throat tube section, with the gap size between 0.05-0.5mm. The intake pipe is located outside the intake chamber and is perpendicularly connected to the intake chamber. The intake pipe is connected to the outside through a pipe. A silencer, filter, flow metering system, or pressure pump can be installed on the pipe for subsequent optimization and improvement.

[0012] Furthermore, it also includes a swirl-starting unit, which is coaxially installed inside the front end of the outlet section. The swirl-starting unit includes a spiral swirl-starting pressure-reducing guide vane and a guide fluid. The guide fluid has a streamlined bullet-shaped structure, and multiple spiral swirl-starting pressure-reducing guide vanes are arranged at equal arcs at the rear end of the guide fluid. The pitch of the spiral swirl-starting pressure-reducing guide vane is 1.2-2.5 times the inner diameter of the outlet section. The blade height of the spiral swirl-starting pressure-reducing guide vane is smaller than the radius of the outlet section, and the number of blades is equal to the number of parallel Venturi tube channels or an integer multiple thereof.

[0013] Furthermore, it also includes a deswirl unit, which includes deswirl ribs. The deswirl ribs 1 are set on the inner wall of the rear end of the outlet section. The deswirl ribs are multiple acute-angled concave and convex ribs or multiple irregularly distributed protrusions.

[0014] Furthermore, the ribs are either straight or spiral structures with staggered protrusions.

[0015] Furthermore, it also includes an intake gap adjustment unit, which includes an adjustment sleeve one and an adjustment sleeve two. The adjustment sleeve one and the adjustment sleeve two are dynamically sealed together, and the adjustment sleeve two is dynamically sealed together with the front or rear section of the venturi tube. One of the front or rear sections can move back and forth along the central axis under the action of the two adjustment sleeves to adjust the intake gap.

[0016] Compared with the prior art, the beneficial effects of this utility model are as follows: This adjustable multi-channel parallel venturi tube micro / nano bubble generator has the following advantages: This invention effectively avoids the design defects of existing microbubble generators and solves the technical problems of large average bubble size, uneven bubble distribution, low bubble generation efficiency, easy blockage of the injection port, incomplete liquid atomization, difficult installation and maintenance, high energy consumption, and low efficiency of bubble overflow. Attached Figure Description

[0017] Figure 1 This is a schematic cross-sectional view of a venturi tube-type micro / nano bubble generator based on an adjustable multi-channel parallel connection according to this utility model. Figure 2 This is a schematic diagram illustrating the working principle of a venturi tube-type micro / nano bubble generator based on an adjustable multi-channel parallel connection. Figure 3 This is a schematic diagram of the air intake unit of an adjustable multi-channel parallel venturi tube micro / nano bubble generator according to this utility model. Figure 4 This is a schematic diagram of the swirl-starting unit of a venturi tube-type micro / nano bubble generator based on an adjustable multi-channel parallel connection. Figure 5 This is a schematic diagram of the deswirl unit of an adjustable multi-channel parallel Venturi tube micro / nano bubble generator according to the present invention. Figure 6 This utility model relates to a static pressure cloud diagram of an adjustable multi-channel parallel venturi tube micro / nano bubble generator. Figure 7 This utility model relates to a velocity cloud map of an adjustable multi-channel parallel Venturi tube micro / nano bubble generator. Figure 8 This is a turbulence dissipation cloud map of an adjustable multi-channel parallel Venturi tube micro / nano bubble generator according to this utility model.

[0018] In the attached diagram, 1 is the Venturi tube, 11 is the inlet section, 12 is the contraction section, 13 is the throat section, 14 is the throat tube section, 15 is the expansion section, 16 is the outlet section, 2 is the intake unit, 21 is the intake chamber, 22 is the intake gap, 23 is the intake pipe, 3 is the swirl unit, 31 is the spiral swirl-starting pressure-reducing guide vane, 32 is the guide fluid, 4 is the deswirl unit, 41 is the deswirl rib, 5 is the intake gap adjustment unit, 51 is the adjustment sleeve one, and 52 is the adjustment sleeve two. Detailed Implementation

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] In the description of this utility model, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0021] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to 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 utility model according to the specific circumstances.

[0022] Please see Figure 1-5 The present invention provides the following technical solution: like Figure 1 As shown, an adjustable multi-channel parallel Venturi tube micro / nano bubble generator includes a Venturi tube 1 and an air intake unit 2. The Venturi tube 1 includes a front section and a rear section. The front section includes an inlet section 11, a plurality of constriction sections 12, and a plurality of throat sections 13 arranged in parallel along the water flow direction, all arranged coaxially. The constriction sections 12 and throat sections 13 are provided with outer rings. The rear section includes a plurality of throat sections 14, a plurality of expansion sections 15, and an outlet section 16 arranged in parallel along the water flow direction, all arranged coaxially. The throat sections 14 and expansion sections 15 are provided with outer rings. The corresponding constriction sections 12, throat sections 13, throat sections 14, and expansion sections 15 form an independent Venturi tube channel. The air intake unit 2 is located at the front or rear end of the Venturi tube 1.

[0023] Among them, such as Figure 1 , 3 As shown, the intake unit 2 includes an intake chamber 21, an intake gap 22, and an intake pipe 23. The front and rear sections of the venturi tube 1 form the intake chamber 21 through their respective outer rings. An intake gap 22 is provided at the connection between the throat section 13 and the throat tube section 14, with the gap size between 0.05-0.5mm. The intake pipe 23 is located outside the intake chamber 21 and is perpendicularly connected to the intake chamber 21. The intake pipe 23 is connected to the outside through a pipe. A silencer, filter, flow metering system, or pressure pump can be installed on the pipe for subsequent optimization and improvement.

[0024] The contraction section 12 has a continuously contracting conical structure within its internal channel, with a rounded transition between the contraction section 12 and the throat section 13. The expansion section 15 has a continuously expanding conical structure within its internal channel, with a rounded transition between the expansion section 15 and the throat section 14. The ratio of the sum of the inner diameter cross-sectional areas of the throat section 13 and the throat section 14 to the inner diameter cross-sectional area of ​​the inlet section 11 is 0.05-0.1, and the ratio of the sum of the lengths of the throat section 13 and the throat section 14 to their inner diameters is 1.5-3. The contraction angle of the contraction section 12 is 30°–120°, and the expansion angle of the expansion section 15 is 30°–120°. The parallel throat sections 13 and 14 connect to the convex and concave portions of the corresponding conical structures of the contraction section 12 and the expansion section 15, respectively, with the convex and concave surfaces having the same taper angle of 60°–90°.

[0025] As an optional implementation method, such as Figure 4 As shown, it also includes a swirl-starting unit 3, which is coaxially installed inside the front end of the outlet section 16. The swirl-starting unit 3 includes a spiral swirl-starting pressure-reducing guide vane 31 and a guide fluid 32. The guide fluid 32 has a streamlined bullet-shaped structure, and multiple spiral swirl-starting pressure-reducing guide vanes 31 are arranged at equal arcs at the rear end of the guide fluid 32. The pitch of the spiral swirl-starting pressure-reducing guide vane 31 is 1.2-2.5 times the inner diameter of the outlet section 16. The blade height of the spiral swirl-starting pressure-reducing guide vane 31 is less than the radius of the outlet section 16, and the number of blades is equal to the number of parallel Venturi tube channels or an integer multiple thereof. The ratio of the inner diameter of the guide fluid 32 to the inner diameter of the outlet section 16 is 0.20-0.50, the ratio of the height of the spiral swirl-starting pressure-reducing guide vane 31 to the length of the outlet section 16 is 0.15-0.3, and the thickness of the blades is 1.2-2 mm. The spiral-shaped swirl-inducing and pressure-reducing guide vane 31 and the guide fluid 32 cause the parallel two-phase flow to swirl, forming a swirling flow. The strong swirling shear force generated by this flow effectively breaks up the initial bubbles and reduces the bubble size.

[0026] As an optional implementation method, such as Figure 1-2 As shown in Figure 5, the system also includes a deswirl unit 4, which includes deswirl ribs 41. These ribs 41 are located on the inner wall of the rear end of the outlet section 16. Each deswirl rib 41 is a straight, acute-angled, concave-convex rib evenly distributed along the inner wall of the outlet section 16, with a rib height of 0.2-1 mm and a width of 1.5-3 mm. When the two-phase flow passes through the outlet section 16, the two-phase flow of the swirling flow contacts the acute-angled edge of the deswirl ribs 41, deswirls the swirling water flow, allowing the two-phase flow to be subjected to forces in different directions during the flow process. This enhances gas-liquid layer mixing, strengthens gas-liquid dissolved gas mass transfer, and improves the uniformity of bubble dispersion.

[0027] As an optional implementation method, such as Figure 1-2As shown, it also includes an intake gap adjustment unit 5, which includes an adjustment sleeve 1 51 and an adjustment sleeve 2 52. The adjustment sleeve 1 51 and the adjustment sleeve 2 52 are dynamically sealed together, and the adjustment sleeve 2 52 is dynamically sealed to the front or rear section of the venturi tube 1. One of the front or rear sections can move back and forth along the central axis under the action of the two adjustment sleeves to adjust the intake gap 22.

[0028] This invention is based on the working principle of an adjustable multi-channel parallel Venturi tube micro / nano bubble generator: through the synergistic action of the Venturi tube 1, the air intake unit 2, the swirl-inducing unit 3, the deswirl-de-swirl unit 4, and the air intake gap adjustment unit 5, when the liquid enters the inlet section 11 through the air intake gap adjustment unit 5, it enters the contraction section 12 of each Venturi tube. According to Bernoulli's principle, the liquid flow rate increases and the pressure decreases, thus forming a negative pressure in the throat section 13 and the throat tube section 14. Gas is drawn in through the air intake gap 22 set at the connection of the throat section 13 and the throat tube section 14 for mixing, shearing, foaming, and breaking. Since the gas enters in a thin annular, multi-channel manner, it forms a multi-stream gas-liquid two-phase flow rich in microbubbles. After this two-phase flow passes through the expansion section 15, the jet flow is converted into a low-pressure swirling flow by the spiral swirl-inducing and pressure-reducing guide plate 31. Because it is a parallel multi-channel Venturi tube, the multi-stream two-phase flow generates swirling shearing and collision. Under this action, the initial two-phase flow is further broken up and refined, and the flow velocity of the two-phase flow is reduced. Subsequently, multiple two-phase flows merge into a single two-phase flow and diffuse along the sidewall at the rear end of the outlet section 16. Due to the presence of swirling flow, the swirling flow collides, cuts, and deswirls with multiple sharp-angled ribs on the inner wall, converting the swirling flow into a jet, eliminating kinetic energy, and reducing collision and aggregation between microbubbles. Under this influence, the bubbles will break up and disperse again, thereby further reducing the bubble size to achieve efficient generation of micro- and nano-bubbles, improving the uniformity of bubble distribution and bubble formation efficiency. Due to the reduced kinetic energy, slower flow velocity, and near-disappearance of pressure, bubbles overflow more easily and for a longer time, resulting in more complete gas-liquid separation and easier bubble collection and processing.

[0029] In the field of liquid atomization technology, after the incoming liquid and gas are switched into the inlet channel, the gas chamber becomes a liquid chamber. When the high-pressure gas passes through the throat section from the contraction section 12, according to Bernoulli's principle, the gas velocity increases and the pressure decreases, thus forming a negative pressure in the throat section. Liquid is drawn in from the gap at the connection between the throat section 13 and the throat section 14 to form multiple two-phase flows. The two-phase flow is ejected from the expansion section and cut and converted into a swirling flow by the spiral swirl-reducing pressure guide plate 31. It then swirles out along the wall of the outlet section 16. The swirling flow collides, cuts, and deswirls with multiple sharp-angled concave and convex ribs or multiple protrusions on the inner wall, turning the swirling flow into a jet flow. This reduces the collision and aggregation between microbubbles, and the bubbles will break again under this influence, thereby further reducing the bubble size and achieving efficient generation of micro-nano bubbles. When the two-phase flow flows out from the outlet section 16, a very fine liquid mist is generated due to the bursting effect of the bubbles. When atomizing various high-viscosity liquids, a certain pressure can be applied to the liquid flow in advance to facilitate better liquid intake by the micro / nano bubble generator. Because the inlet gap 22 is adjustable, the injection pressure is adjustable, the gas-liquid mixing degree is high, and the atomization quality is good, the micro / nano bubble generator is well-suited for atomizing various high-viscosity liquids.

[0030] This invention analyzes the computational fluid dynamics (CFD) numerical simulation results of a multi-channel parallel Venturi tube micro / nano bubble generator. Specifically, the boundary condition for the liquid inlet of the contraction section 12 is set to volumetric flow rate of 450 L / min; the boundary condition for the gas injection gap 22 is set to ambient pressure outlet one with a pressure of 101325 Pa; and the boundary condition for the water outlet of the outlet section 16 is set to ambient pressure outlet two with a pressure of 101325 Pa.

[0031] (1) Analysis of Static Pressure Simulation Results Figure 6 To capture the static pressure distribution cloud map at x=0, it can be seen that along the axial direction, the pressure is greatest at the inlet of the contraction section 12. After entering the contraction section 12, the pressure gradient decreases with increasing flow velocity, forming a low-pressure region in the throat section 14 to facilitate the entry of external gas. In the expansion section 15, due to the decrease in flow velocity, the pressure increases, and a large amount of gas dissolved in the water is released, generating a large number of micro- and nano-bubbles. Before and after the swirl unit 3, the pressure distribution changes significantly because the swirling flow field increases the pressure gradient at that point. As a result, the bubbles in the two-phase flow are subjected to swirling shear force, causing the bubbles to break up. After passing through the fluid control unit, the pressure during the process of the swirling flow being converted into a jet flow is close to the ambient pressure, which facilitates the escape and separation of bubbles in the two-phase flow.

[0032] (2) Analysis of velocity simulation results Figure 7To capture the velocity gradient distribution cloud map at x=0, it can be seen that when the liquid flow passes through the throat section 14, according to Bernoulli's principle, the cross-sectional area of ​​the flow channel decreases, leading to an increase in velocity. When the gas-liquid two-phase flow passes through the expansion section 15, the cross-sectional area of ​​the flow channel increases, and the flow velocity decreases, thus resulting in a large velocity gradient. When the two-phase flow enters the deswirl unit 4, the velocity decreases significantly. The main reason is that after the two-phase flow starts to swirl in the swirl unit 3, when it passes through the deswirl unit 4, it breaks up the swirling flow, turning the fluid from a swirling flow back into a jet flow, thus producing a significant velocity reduction. In addition, during the deswirl breaking process, the two-phase flow is fully mixed, thereby promoting bubble breakage and enhancing the mass transfer effect.

[0033] (3) Analysis of simulation results of turbulent energy dissipation rate Figure 8 The turbulent energy dissipation rate contour plot of the x=0 plane shows that the turbulent energy dissipation rate is relatively high in the areas before and after the swirl-initiating unit 3, the deswirl-initiating unit 4, and the sidewall region of the expansion section 15. The main reason is that when the mixed flow passes through the above regions, the large radial velocity difference forms turbulent eddies, which significantly increases the turbulent energy dissipation rate and reduces the stability of the gas-liquid interface, making the bubbles more prone to breakage.

[0034] Conclusion and Analysis: Through CFD numerical simulation calculations of specific embodiments of this utility model and analysis of the flow field static pressure distribution cloud map, velocity gradient distribution cloud map, and turbulent energy dissipation rate cloud map, the results fully demonstrate that the specific embodiments of this utility model have high bubble formation efficiency, proving the effectiveness and feasibility of this utility model.

[0035] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.

Claims

1. A venturi tube-type micro / nano bubble generator based on adjustable multi-channel parallel connection, characterized in that: The system includes a venturi tube (1) and an air intake unit (2). The venturi tube (1) includes a front section and a rear section. The front section includes an inlet section (11) arranged coaxially along the water flow direction, multiple converging sections (12) arranged in parallel, and multiple throat sections (13) arranged in parallel. The converging sections (12) and throat sections (13) are provided with outer rings. The rear section includes multiple throat sections (14) arranged coaxially along the water flow direction, multiple expanding sections (15) arranged in parallel, and an outlet section (16). The throat sections (14) and expanding sections (15) are provided with outer rings. The corresponding converging sections (12), throat sections (13), throat sections (14), and expanding sections (15) form an independent venturi tube channel. The air intake unit (2) is located at the front or rear end of the venturi tube (1).

2. The Venturi tube-type micro / nano bubble generator based on adjustable multi-channel parallel connection according to claim 1, characterized in that: The internal channel of the contraction section (12) is a continuously contracting conical structure, and there is a rounded transition between the contraction section (12) and the throat section (13); the internal channel of the expansion section (15) is a continuously expanding conical structure, and there is a rounded transition between the expansion section (15) and the throat section (14).

3. The Venturi tube-type micro / nano bubble generator based on adjustable multi-channel parallel connection according to claim 2, characterized in that: The ratio of the sum of the inner diameter cross-sectional areas of the throat segment (13) and the throat tube segment (14) to the inner diameter cross-sectional area of ​​the inlet segment (11) is 0.05-0.1, and the ratio of the sum of the lengths of the throat segment (13) and the throat tube segment (14) to their inner diameter is 1.5-3.

4. A venturi tube-type micro / nano bubble generator based on adjustable multi-channel parallel connection according to claim 2, characterized in that: The contraction angle of the contraction segment (12) is 30° to 120°, and the expansion angle of the expansion segment (15) is 30° to 120°.

5. A venturi tube-type micro / nano bubble generator based on adjustable multi-channel parallel connection according to claim 2, characterized in that: The parallel throat segment (13) and throat tube segment (14) are respectively connected to the convex and concave parts of the conical structure of the corresponding contraction segment (12) and expansion segment (15). The taper of the convex and concave surfaces is consistent, and the angle is 60°-90°.

6. A venturi tube-type micro / nano bubble generator based on adjustable multi-channel parallel connection according to claim 1, characterized in that: The intake unit (2) includes an intake chamber (21), an intake gap (22), and an intake pipe (23). The front and rear sections of the venturi tube (1) form the intake chamber (21) through their respective outer rings. An intake gap (22) is provided at the connection between the throat section (13) and the throat tube section (14). The gap size is between 0.05-0.5mm. The intake pipe (23) is located outside the intake chamber (21) and is perpendicularly connected to the intake chamber (21). The intake pipe (23) is connected to the outside through a pipe.

7. A venturi tube-type micro / nano bubble generator based on adjustable multi-channel parallel connection according to claim 1, characterized in that: It also includes a swirl unit (3), which is coaxially installed inside the front end of the outlet section (16). The swirl unit (3) includes a spiral swirl pressure reducing guide vane (31) and a guide fluid (32). The guide fluid (32) has a streamlined bullet head structure, and multiple spiral swirl pressure reducing guide vanes (31) are arranged at the rear end of the guide fluid (32) with equal arc. The pitch of the spiral swirl pressure reducing guide vane (31) is 1.2-2.5 times the inner diameter of the outlet section (16). The blade height of the spiral swirl pressure reducing guide vane (31) is less than the radius of the outlet section (16), and the number of blades is equal to the number of parallel Venturi tube channels or an integer multiple thereof.

8. A venturi tube-type micro / nano bubble generator based on adjustable multi-channel parallel connection according to claim 1, characterized in that: It also includes a deswirl unit (4), which includes a deswirl rib (41). The deswirl rib (41) is set on the inner wall of the rear end of the outlet section (16). The deswirl rib (41) is a series of acute-angled concave and convex ribs or a series of irregularly distributed protrusions.

9. A venturi tube-type micro / nano bubble generator based on adjustable multi-channel parallel connection according to claim 8, characterized in that: The ribs are either straight or spiral, with staggered arrangement of protrusions.

10. A venturi tube-type micro / nano bubble generator based on adjustable multi-channel parallel connection according to claim 1, characterized in that: It also includes an intake gap adjustment unit (5), which includes an adjustment sleeve one (51) and an adjustment sleeve two (52). The adjustment sleeve one (51) and the adjustment sleeve two (52) are dynamically sealed together, and the adjustment sleeve two (52) is dynamically sealed together with the front or rear section of the venturi tube (1).

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