JP6169749B1 - Microbubble generator - Google Patents

Abstract

An object of the present invention is to efficiently generate microbubbles and improve the ejection efficiency of a liquid containing microbubbles. A fine bubble generating device includes a main channel through which a liquid flows and an air supply channel for introducing gas into the main channel. Specifically, the main flow path includes a throttle portion whose inner diameter is smaller than the surroundings, and a suction chamber that is provided on the downstream side of the throttle portion and mixes liquid and gas, and the air supply path is a suction chamber. The air supply hole is connected to the suction chamber while inclining in the liquid flow direction in a vertical cross-sectional view of the fine bubble generating device, and generates a spiral swirl flow in the main channel by introducing the gas. Thus, the central axis of the air supply hole and the central axis of the main flow path are arranged so as not to intersect. [Selection] Figure 1

Description

  The present invention relates to a microbubble generator.

  Conventionally, various techniques for generating minute bubbles called so-called microbubbles have been proposed. For example, a circulating flow generator has been proposed in which a gas blowing hole is inclined at an acute angle with respect to the liquid traveling direction in the flow path and has a tangential component of the wall surface surrounding the flow path. (Patent Document 1). In the present technology, a compressor is connected and gas is blown into a flow path through a gas blowing hole, thereby generating a swirling flow in the flow path and simultaneously generating a circulating flow and gas-liquid mixing.

  Also proposed is a technology that employs a so-called Venturi tube in the microbubble generator, and the gas introduced into the main passage may be pumped into the gas introduction hole by a blower or the like, or may be naturally sucked into the main passage. (Patent Document 2). In addition, a technique for generating a negative pressure by using a venturi pipe in a bubble generating nozzle or a bubble generator has been proposed (Patent Documents 3 and 4).

Japanese Patent No. 3717767 Japanese Patent No. 5257819 Japanese Patent No. 49999996 JP 2014-33999 A

  Conventionally, various techniques for generating microbubbles have been proposed. On the other hand, the use of microbubbles includes washing and water purification. When used for cleaning, the microbubbles are crushed by colliding a water stream containing microbubbles with the object to be cleaned, and dirt can be easily separated from the object to be cleaned by the impact pressure. In addition, when used for water purification of ponds and marshes, in order to supply microbubbles to the entire purification target, the greater the amount of bubbles relative to the water injection flow rate, the greater the jet force and the greater the agitation. The effect is increased.

  Therefore, an object of the present invention is to improve the ejection efficiency of a liquid containing microbubbles, together with the optimum structure of an apparatus that efficiently generates microbubbles.

  The fine bubble generating apparatus according to the present embodiment includes a main channel through which a liquid flows and an air supply channel that introduces gas into the main channel. Specifically, the main flow path includes a throttle portion whose inner diameter is smaller than the surroundings, and a suction chamber that is provided on the downstream side of the throttle portion and guides gas to the liquid flow of the liquid. It has air supply holes that communicate with the suction chamber, and the air supply holes are connected to the suction chamber at an angle in the liquid flow direction in a longitudinal sectional view of the fine bubble generating device, and spirally formed in the main flow path by introducing gas The central axis of the air supply hole and the central axis of the main flow path are arranged so as not to intersect with each other so as to generate a swirling flow.

In this way, the water flow from the throttle part provided in the main flow path becomes high speed, negative pressure is generated by the so-called venturi effect, and gas is supplied through the air supply holes in the suction chamber provided downstream of the throttle part. It becomes possible to suck smoothly. Further, since the air supply hole is connected to the suction chamber at an angle in the liquid flow direction in the main flow path, it is possible to reduce the loss of the liquid flow velocity due to the introduction of the gas. Therefore, the ejection efficiency of the fine bubble generating device can be improved. In addition, the configuration in which the central axis of the air supply hole and the main flow path is shifted can generate a swirling flow having various strengths in the main flow path, and the fine bubbles can be efficiently generated by the shearing force generated in the main flow path. it can.

  Further, the throttle portion may be configured such that the downstream end thereof protrudes into the suction chamber. In this way, the flow of the gas-liquid flow in the suction chamber can be controlled.

  The suction chamber may have an inner diameter that gradually decreases toward the downstream side of the main flow path. In this way, liquid and gas can be smoothly guided to the throat portion.

  The contents described in the means for solving the problems can be combined as much as possible without departing from the problems and technical ideas of the present invention.

  While generating microbubbles efficiently, the ejection efficiency of the liquid containing microbubbles can be improved.

It is the longitudinal cross-sectional view which cut | disconnected the microbubble production | generation nozzle along the main flow path direction through which the liquid flows. It is an internal permeation | transmission perspective view of a microbubble production | generation nozzle. It is the cross-sectional perspective view which cut | disconnected the micro bubble production | generation nozzle along the main flow path direction through which the liquid flows. It is a front view of a microbubble production | generation nozzle. It is a top view of a microbubble production | generation nozzle. It is a left view of a microbubble production | generation nozzle. It is BB sectional drawing in FIG. 5 of a microbubble production | generation nozzle. It is CC sectional drawing in FIG. 5 of a microbubble production | generation nozzle. It is an internal permeation | transmission perspective view which shows the state which decomposed | disassembled the upstream member and the downstream member. It is the internal permeation | transmission figure which showed the air supply hole in a microbubble production | generation nozzle from the front. It is a graph which shows the result of having simulated the pressure and flow velocity in an apparatus. The magnitude of the water pressure when the extension line of the axial center of the air supply hole is offset from the central axis of the main flow path and when the extension line of the axial center of the supply air hole intersects the central axis of the main flow path It is a graph which shows the result of having simulated. It is a figure for demonstrating the air supply hole provided so that the extension line of the axial center of an air supply hole might cross the center axis | shaft of a main flow path. It is a graph which shows the result of having measured the number of fine particles produced | generated with a microbubble production | generation nozzle with the fine particle measuring device. It is a graph which shows the amount of dissolved oxygen when the apparatus is operated using the microbubble generating nozzle according to the embodiment and when the apparatus is not operated. It is a longitudinal cross-sectional view which shows the upstream member in which the rate of change of the diameter of a reduced diameter part is not constant.

Hereinafter, a microbubble generating nozzle according to an embodiment of the present invention will be described with reference to the drawings. However, the embodiment described below is an example of an apparatus, and the apparatus according to the present invention is not limited to the following configuration.

  In the present embodiment, bubbles having a diameter of 100 μm or less are collectively referred to as “fine bubbles”. Of the fine bubbles, those having a diameter of 1 to 100 μm are referred to as “micro bubbles”, and those having a diameter of 1 μm or less are referred to as “ultra fine bubbles (nano bubbles)”. Microbubbles are not visible as bubbles and are recognized as white turbidity in water. Ultra fine bubbles are bubbles having a size that cannot be visually confirmed. In addition, bubbles having a diameter of 50 μm or more have a property of rising while immediately expanding. On the other hand, bubbles having a diameter of 6 μm to 50 μm float at a speed of about several mm / s to several tens μm / s while contracting due to surface tension.

  The apparatus according to the present embodiment mainly generates microbubbles. However, the production | generation of an ultra fine bubble is not excluded, The apparatus which concerns on this embodiment may produce | generate the fine bubble containing an ultra fine bubble. The fine bubbles are also referred to as “micro bubbles” according to the present invention.

<Configuration and action>
FIG. 1 is a longitudinal sectional view of the microbubble generating nozzle 1 according to the present embodiment cut along the direction of the main flow path through which the liquid flows. FIG. 2 is an internal transparent perspective view of the microbubble generating nozzle 1. 3 is a cross-sectional perspective view of the microbubble generating nozzle 1 cut at the same position as in FIG. The microbubble generating nozzle 1 includes a main flow path (indicated by an alternate long and short dash line in FIG. 1) through which a liquid such as water flows in a straight line, and an air supply path (two lines in FIG. Dotted line arrows). Note that the one-dot chain line arrow and the two-dot chain line arrow represent the direction in which the fluid flows, respectively.

  In the present embodiment, description will be made assuming that water is supplied to the main flow path and air is sucked from the air supply path. Water may be pumped by connecting a pump or the like, or water may be fed in connection with water. Further, air is sucked by the venturi effect without needing to be pumped as will be described later. And while mixing water and air in the microbubble production | generation nozzle 1, a microbubble is produced | generated and the water containing a microbubble is injected. In this embodiment, for the sake of convenience, the direction in which water containing microbubbles is jetted is referred to as the front, and the side to which water is supplied is referred to as the back. The direction in which the air supply path is provided is referred to as “up”.

  FIG. 4 is a front view of the microbubble generating nozzle 1 as seen from the front. FIG. 5 is a plan view of the microbubble generating nozzle 1 as seen from above. FIG. 6 is a left side view of the microbubble generating nozzle 1. Moreover, FIG. 1 mentioned above is AA sectional drawing in FIG. 5, and is corresponded to the longitudinal cross-sectional view which cut | disconnected the microbubble production | generation nozzle 1 in the center of the width direction. FIG. 7 is a cross-sectional view taken along the line B-B in FIG. 5, and is a vertical cross-sectional view in which the microbubble generating nozzle 1 is cut at a position to the right of the front from the center in the width direction. FIG. 8 is a cross-sectional view taken along the line CC in FIG. 5, and is a cross-sectional view of the microbubble generating nozzle 1 cut along a plane perpendicular to the main flow path at the center of the air supply path.

  As shown in the cross-sectional view and the internal permeation diagram described above, the microbubble generating nozzle 1 is formed by combining two members. Specifically, the microbubble generating nozzle 1 includes an upstream member 2 that is a first member located on the upstream side of the main flow path, and a downstream member 3 that is a second member located on the downstream side of the main flow path. With. The upstream member 2 and the downstream member 3 can be formed using a metal such as stainless steel or other materials, for example.

FIG. 9 is an internally transparent perspective view of the microbubble generating nozzle 1 showing a state in which the upstream member 2 and the downstream member 3 are disassembled. As can be seen from FIG. 9 and the cross-sectional views described above, the upstream member 2
And the downstream member 3 has a portion where the inner diameter of the upstream member 2 and the outer diameter of the downstream member 3 are the same, and the downstream member 3 is inserted into the upstream member 2. To connect them. Specifically, the inner diameter of the downstream end of the upstream member 2 is the same as the outer diameter of the corresponding portion of the downstream member 3.

  Further, the downstream member 3 has a portion whose outer diameter is smaller than the inner diameter of the upstream member 2, and the gas suction chamber 4 is interposed between the upstream member 2 and the downstream member 3 in a combined state. It is formed. Specifically, the outer diameter of the upstream end portion of the downstream member 3 is smaller than the inner diameter of the corresponding portion of the upstream member 2. The gas suction chamber 4 is an annular space provided in the microbubble generating nozzle 1. The sucked air is introduced into the main channel from the periphery of the main channel via the gas suction chamber 4.

  Further, as can be seen from the longitudinal sectional view and the like, the size of the diameter of the main channel changes in the microbubble generating nozzle 1. Even if the size of the diameter changes, the center of the axis in the flow direction of the main channel can be said to be substantially linear.

  The upstream member 2 of the microbubble generating nozzle 1 includes a water supply path 21 through which water is supplied from a water supply pipe 5 (only the inner diameter is shown in FIG. 1) connected to the upstream side of the main flow path. The water supply path 21 is a cylindrical space having a constant diameter.

  The upstream member 2 has a reduced diameter portion 22 whose diameter gradually decreases on the downstream side of the water supply channel 21. That is, the reduced diameter portion 22 is a frustoconical space. The main flow path is a so-called Venturi tube, and in the reduced diameter portion 22, the flow rate of water passing through the inside increases and the pressure decreases.

  Further, the upstream member 2 has a throttle portion 23 that is a cylindrical space having the smallest inner diameter on the downstream side of the reduced diameter portion 22. The inner diameter of the throttle portion 23 is about 0.1 to 0.4 times the inner diameter of the water supply passage 21. At the downstream end of the throttle portion 23, there is provided a protruding tube 24 in which a circular tube protrudes in the downstream direction. The flow rate of the water that has risen in the reduced diameter portion 22 becomes faster in the throttle portion 23. Further, in the throttle portion 23, the pressure decreases to near vacuum according to the flow velocity. Further, when the pressure drops below the saturated vapor pressure, cavitation bubbles are generated by the liberation of dissolved air with the bubble nuclei existing in water as nuclei.

  The upstream member 2 has an air supply path 25 at a position communicating with the gas suction chamber 4 described above. Air is supplied to the air supply path 25 through an air supply pipe 6 (only the inner diameter is shown in FIG. 1). The air supply path 25 is connected to, for example, outside air via the air supply pipe 6. Further, the supply pipe 6 may be provided with an adjustment valve 7 (a symbol is shown in FIG. 1) for adjusting the inflow amount of outside air.

  Further, the downstream member 3 of the microbubble generating nozzle 1 has a suction chamber 31 at its upstream end. The diameter of the suction chamber 31 gradually decreases toward the downstream side. That is, the suction chamber 31 can also be said to be a truncated cone space. Further, in a state where the upstream member 2 and the downstream member 3 are connected, the protruding tube 24 of the upstream member 2 protrudes into the suction chamber 31. A plurality of air supply holes 32 for supplying air are provided between the suction chamber 31 and the gas suction chamber 4, and the suction chamber 31 and the gas suction chamber 4 communicate with each other. In the suction chamber 31, negative pressure is generated by the venturi effect, and outside air is sucked from the air supply holes 32.

As can be seen from the longitudinal sectional view and the like, the air supply holes 32 are inclined toward the downstream side of the main flow path. In other words, the air supply holes 32 extend from the connecting portion with the suction chamber 31 slightly inclined to the upstream side of the main flow path. That is, the air supply holes 32 merge with the main channel in a direction that does not oppose the water flow in the main channel. Due to this inclination, for example, water and air can be smoothly joined as compared with the case where the main flow path and the air supply holes 32 are vertically connected. In other words, the loss of momentum of the water flow caused by the supply of air can be reduced. The angle between the air supply hole 32 and the central axis of the main flow path is preferably about 50 to 80 degrees. Further, the taper provided in the suction chamber 31 serves to smooth the merging of water and air and to maintain the speed of the water flow rising at the reduced diameter portion 22 and the throttle portion 23. Further, since the protruding tube 24 protrudes into the suction chamber 31, it is possible to prevent the backflow of the water flow. In order to prevent backflow, it is preferable that the downstream end of the protruding tube 24 protrudes to a position where it intersects with the extension line of the air supply hole 32.

  FIG. 10 is an internal transmission view of the air supply holes 32 in the microbubble generating nozzle 1 as seen from the front. As can be seen from FIG. 10, a cross-sectional view, and the like, the air supply holes 32 are provided so that the extension line of the axial center is shifted from the central axis of the main flow path. Specifically, each air supply hole 32 is provided at a position substantially corresponding to a tangent to the inner wall of the main flow path in a cross-sectional view. That is, the air supply holes 32 are provided so as to intersect the main flow path in a cross-sectional view, and the inner wall of the air supply holes 32 and the inner wall of the main flow path are almost in contact with each other. However, for convenience of manufacture, it is practical to provide the air supply holes 32 closer to the central axis of the main flow path than the inner wall of the main flow path. When air is introduced at such an angle, the air swirls in the suction chamber 31 and flows. Along with this, the water flowing in from the upstream member 2 also swirls in the suction chamber 31 and flows.

  The downstream member 3 has a throat portion 33 that is a cylindrical space having a constant inner diameter on the downstream side of the suction chamber 31. In the throat portion 33, the internal pressure rises above the suction chamber 31, and the water flowing through the main flow path and the air sucked in the suction chamber 31 are mixed. Further, the downstream side member 3 has a diffuser portion 34 whose inner diameter gradually increases on the downstream side of the throat portion 33. The swirling flow generated in the suction chamber 31 forms vortices in the throat portion 33 and the diffuser portion 34, and generates a strong shearing force. At the same time, the cavitation bubbles generated in the reduced diameter portion 22 and the throttle portion 23 collide with the air introduced from the air supply holes 32, so that the bubbles are refined. As described above, the air taken in from the air supply holes 32 is atomized to generate microbubbles. Then, a jet including microbubbles is ejected from the diffuser portion 34.

  According to the microbubble generating nozzle 1 according to the present embodiment, it is possible to reduce the loss of momentum (flow velocity) of the water flow supplied to the main flow path, and to generate a microbubble-containing jet having a high injection force.

  In the microbubble generating nozzle 1, in order to make the negative pressure region have an appropriate length, it is preferable to provide the throttle portion 23 and the diffuser portion 34. If these are not provided, the performance deteriorates. Further, if the throat portion 33 is not provided, a water flow that flows backward in the diffuser portion 34 may occur. By optimizing the ratio of the reduced diameter portion 22, the throttle portion 23, the air supply hole 32, the throat portion 33, and the diffuser portion 34, the microbubble generating nozzle 1 is capable of reducing the amount of water when the supplied water pressure is 0.3 MPa. 80% capacity of air can be self-primed.

<Comparative example>
FIG. 11 is a graph schematically showing the result of simulating the pressure in the apparatus. In the graph of FIG. 11, the vertical axis represents pressure, and the horizontal axis represents the distance from the upstream end of the throttle portion 23 in the apparatus. A solid line indicates a change in pressure when the regulating valve 7 of FIG. 1 is opened and air is introduced (model with air). A one-dot chain line shows a change in pressure when the regulating valve 7 in FIG. 1 is closed and no air is introduced (airless model). The water pressure of the supplied water (relative pressure to the atmosphere) is the same. Further, the generation of cavitation bubbles starts when the pressure becomes equal to or lower than the saturated vapor pressure (cavitation generation pressure in FIG. 11). As shown in FIG. 11, in both cases where air is introduced and not introduced, generation of cavitation bubbles starts in the throttle portion 23 in front of the suction chamber 31 into which outside air is introduced. Therefore, it can be said that the microbubbles are generated regardless of whether air is introduced from the air supply holes 32 or not.

  FIG. 12 shows a case where the extension line of the axial center of the air supply hole 32 is shifted from the central axis of the main flow path (with a helix), and a case where the air supply hole 32 is provided on the central axis of the main flow path (without a helix). It is a graph which shows typically the result of having simulated the magnitude | size of the water pressure. The water pressure of the supplied water (relative pressure to the atmosphere) is the same. A thick solid line is a graph which shows the water pressure in case the air supply hole 32 which concerns on this embodiment as shown in FIG. 10 is employ | adopted. Further, the thin broken line is a graph showing the water pressure when the air supply holes 32 that do not generate a spiral swirl flow as shown in FIG. 13 are employed. In the example of FIG. 13, the air supply holes are provided so that the extension line of the axial center intersects the central axis of the main flow path. When the air supply holes 32 according to the present embodiment are employed, the water pressure in the throttle portion 23 is equal to or lower than the saturated water vapor pressure (cavitation generation pressure in FIG. 12) generated by cavitation bubbles, and more cavitation bubbles are generated. it is conceivable that. On the other hand, when the air supply holes 32 as shown in FIG. 13 are employed, the generation amount of cavitation bubbles is reduced, and at the same time, the generation efficiency of microbubbles is considered to be reduced. That is, even if the pressure of the supplied water is the same, the flow rate is not sufficiently increased without the helix, and the cavitation generation pressure is not reached at the throttle portion.

<Effect>
FIG. 14 is a graph showing the results of measuring the number of particles generated by the microbubble generating nozzle 1 using a particle measuring machine (particle counter HIAC Royco) installed on the downstream side of the diffuser section 34. In the graph of FIG. 14, the horizontal axis represents the driving pressure (MPa), and the vertical axis represents the number of observations per mL. When the driving pressure is as small as about 0.05 MPa, fine particles are hardly observed, but when the driving pressure is higher than that, it is observed. For the convenience of the observation area of the apparatus, bubbles having a diameter of less than 4 μm are not counted, but it is considered that so-called ultra fine bubbles are also generated.

  FIG. 15 is a graph showing the amount of dissolved oxygen when the apparatus is operated using the microbubble generating nozzle 1 according to the embodiment and when the apparatus is not operated. In the graph of FIG. 15, the horizontal axis represents the ratio of dissolved oxygen amount, and the vertical axis represents time. Moreover, a thick line is a graph which shows the ratio (dissolved oxygen rate) of the dissolved oxygen amount with respect to the saturation amount at the time of connecting the microbubble production | generation nozzle 1 to a pump and circulating the water of a pond, and producing | generating a microbubble. . The operation of the apparatus was performed only during the day of the first day indicated as “MB operation” on the horizontal axis. Moreover, a thin line is a graph which shows a dissolved oxygen rate when not producing | generating a microbubble. Before the start, the oxygen dissolution rate was a little less than 90%, and the oxygen dissolution rate was higher when the apparatus was operated even on the second day. Since microbubbles and ultrafine bubbles remain in water for a long time, it is considered that the generated microbubbles remain. In addition, the microbubble generating nozzle 1 according to the embodiment has good injection efficiency, and was able to spread evenly in a pond of several meters square. Although this experiment was conducted in the early winter when the oxygen dissolution rate did not decrease relatively, it is considered that the usefulness of this device will increase because the oxygen dissolution rate is further decreased in summer due to temperature rise.

<Modification>
In the above-described embodiment, it has been described that microbubbles of air are generated in water. However, a liquid other than water may be supplied to the main channel. Further, a gas other than air may be introduced from the air supply path 25. When introducing a gas other than air from the air supply path 25, the air supply path 25 is connected to a cylinder or the like that holds the target gas, not the outside air. In this way, microbubbles of various gases such as oxygen, nitrogen, hydrogen, carbon dioxide and ozone can be generated.

  Further, the diameter of the water supply channel 21 is not constant and may be tapered as long as it is equal to or larger than a predetermined size at which a desired flow rate can be obtained. In addition, the taper angles of the reduced diameter portion 22, the suction chamber 31, the diffuser portion 34, and the like are not limited to the illustrated example, and appropriate values can be adopted.

  FIG. 16 is a longitudinal sectional view showing an example of the upstream member 2 in which the rate of change in the diameter of the reduced diameter portion 22 is not constant. In the example of FIG. 16, the boundary between the reduced diameter portion 22 and the water supply channel 21 of the main flow path of the upstream side member of the main flow path and the boundary between the reduced diameter portion 22 and the throttle portion 23 are smooth in the longitudinal sectional view. . In the above-described embodiment, the water supply channel 21, the reduced diameter portion 22, the throttle portion 23, and the like have been described separately for convenience, but the boundary may be ambiguous as shown in FIG. Even in such a mode, for example, if the diameter of the reduced diameter portion 22 monotonously decreases (if the inner diameter gradually decreases toward the downstream side of the main flow path), it functions in the same manner as the above-described embodiment. Moreover, the smoothening of the boundary can suppress a decrease in the flow velocity. The reduced diameter portion 22 having a constant diameter change rate can be formed by, for example, metal processing such as cutting, 3D printing, or the like. In addition, you may make it the shape where the magnitude | size of a diameter changes smoothly also about the other parts where the magnitude | size of a diameter changes like the suction chamber 31, the diffuser part 34, etc. FIG.

  In addition, an appropriate value can be adopted as the inclination angle of the air supply hole 32 with respect to the main flow path. Further, the number of air supply holes 32 is not limited to the illustrated example. The number of air supply holes 32 provided around the suction chamber 31 may be changed to an arbitrary number of 1 or more, and a plurality of rows of air supply holes 32 may be provided before and after the flow direction of the main flow path. .

  The size of the microbubble generating nozzle 1 is not particularly limited. For example, you may make it employ | adopt the microbubble production | generation nozzle 1 of the similar shape expanded and contracted by making the ratio of the magnitude | size of each part the same. If it does in this way, the microbubble production | generation nozzle 1 which processes the flow volume according to the scale of a use can be provided. Therefore, it can respond to various uses from a relatively small water tank to a larger pond.

1: Microbubble generating nozzle 2: Upstream member 21: Water supply path 22: Reduced diameter part 23: Restricted part 24: Thrust pipe 25: Air supply path 3: Downstream member 31: Suction chamber 32: Air supply hole 33: Throat Part 34: diffuser part 4: gas suction chamber 5: water supply pipe 6: air supply pipe 7: regulating valve

Claims (3)

A main flow path through which liquid flows;
An air supply path for introducing gas into the main flow path;
A microbubble generator comprising:
The main flow path includes a throttle portion having an inner diameter smaller than the surroundings, and a suction chamber that is provided downstream of the throttle portion and guides the gas to the liquid flow of the liquid,
The air supply path includes an air supply hole communicating with the suction chamber,
The air supply hole is connected to the suction chamber at an angle toward the liquid flow direction in a vertical cross-sectional view of the fine bubble generating device, and a spiral swirl flow is generated in the main channel by the introduction of the gas. Arranged so that the central axis of the air supply hole and the central axis of the main flow path do not intersect so as to generate ,
The suction chamber is a fine bubble generating device in which the inner diameter of the wall surface gradually decreases toward the downstream side of the main flow path, and the air supply holes communicate with the wall surface . The fine bubble generating device according to claim 1, wherein an end of the throttle portion on the downstream side protrudes into the suction chamber.   The air supply path includes a gas suction chamber that is an annular space around the suction chamber,
  A plurality of air supply holes are connected from the gas suction chamber to the suction chamber.
  The fine bubble production | generation apparatus of Claim 1 or 2.

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