JP2011240211A - Mechanism for generating microbubbles - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mechanism for generating microbubbles effectively generating high speed flow advantageous to the micronization of bubbles.SOLUTION: A flow-introduction section 150 made to have a cross section smaller than that of a preparatory expanded section 156 at the end part connected to the preparatory expanded section 156 and greater than that of a throttle 21J, is formed. A stagnant area wherein the flow speed is low, is formed as a flow buffer space 155 on the circumference of the connecting opening of the flow-introduction section 150 at the upstream-side end part of the preparatory expanded section 156. The outer circumference of the main flow running straight into the preparatory expanded section 156 from the flow-introduction section 150 turns in the direction opposite to the main flow while spreading in the flow buffer space 155 to generate a swirling flow. Namely, the swirling flow generated in a manner of surrounding the main flow in the flow buffer space 155 reduces the pressure drop of the main flow resulting from the friction between the main flow and the wall face of a flow path FP, whereby the liquid flow can be kept at high speed in the preparatory expanded section 156.

Description

  The present invention relates to a microbubble generation mechanism.

  Microbubbles formed in water are classified into millibubbles or microbubbles (further, micro / nano bubbles, nano bubbles, etc.) depending on their sizes. Millibubbles are huge bubbles to some extent, which rise rapidly in water and eventually rupture and disappear at the surface of the water. On the other hand, bubbles with a diameter of 50 μm or less are fine, so they have a long residence time in water and are excellent in gas dissolving ability, so they further shrink in water, and finally disappear in water ( It has a special property of completely dissolving), and it is becoming common to call this microbubble (Non-patent Document 1).

  In recent years, such microbubbles have been applied to many applications, and various microbubble generators that can be incorporated into, for example, a bubble water jetting section for a bathtub or a shower have been proposed (Patent Documents 1 to 4). Basically, water is supplied to a throttling mechanism such as a venturi pipe, and the air dissolved in the water is removed by the pressure reducing effect caused by Bernoulli's principle when passing through the throttling mechanism at a high flow rate. A cavitation system that precipitates as microbubbles is adopted. Further, if the gas is previously dissolved in water under pressure and supplied to the squeezing mechanism, the amount of bubble deposition accompanying decompression foaming increases, and finer bubbles with a higher concentration can be obtained.

JP 2008-73432 A JP 2007-209509 A JP 2007-50341 A JP 2006-116518 A

Internet homepage (http://unit.aist.go.jp/emtech-ri/26env-fluid/pdf/takahashi.pdfResearch on microbubbles and nanobubbles')

  However, the conventional microbubble generation mechanism has a drawback that the flow velocity when passing through the throttle mechanism is likely to be insufficient, and the level of bubble miniaturization is not sufficient. In particular, in the case of a gas introduction member (also referred to as an ejector / nozzle) in which a nozzle hole for gas suction is formed in communication in the throttle part, suction is introduced into the liquid if the flow velocity when passing through the throttle mechanism is insufficient. This is directly linked to the problem of the absolute amount of gas being exhausted. In addition, in the conventional microbubble generation mechanism described above, as a flow element for further finely pulverizing the bubbles deposited in the water flow after passing, vortex generation accompanying the opening / turbulence of the water flow itself that has passed through the throttle hole I can only expect. Furthermore, when trying to generate high-concentration bubbles by pressure-dissolving the gas, it is a problem that the bubble coarsening due to the rapid precipitation of the gas is particularly easy to proceed.

  An object of the present invention is to provide a microbubble generation mechanism capable of effectively generating a high-speed flow advantageous for bubble miniaturization.

Means for Solving the Problems and Effects of the Invention

In order to solve the above problems, the microbubble generation mechanism of the present invention is:
A flow path forming member having a liquid inlet and a liquid outlet and having a flow path from the liquid inlet toward the liquid outlet formed therein,
A throttling portion formed between the liquid inlet and the liquid outlet in the flow direction, and having a smaller cross-sectional area and a higher flow velocity than both of the liquid inlet and the liquid outlet;
A preparatory enlarged portion formed adjacent to the upstream side of the throttle portion so that the cross-sectional area is larger than the throttle portion over the entire length in the flow direction;
Connected to form a stepped surface in the circumferential direction with respect to the flow axis in a form adjacent to the upstream side of the preparatory enlarged portion, and has a smaller cross-sectional area than the preparatory enlarged portion at the connection side end with the preparatory enlarged portion. And a flow introduction portion formed to have a larger cross-sectional area than the throttle portion,
The outer peripheral area of the preparation expansion section on the side connected to the flow introduction section forms a flow buffer space that protects the periphery of the main flow that goes straight from the flow introduction section into the preparation expansion section.

  In the microbubble generation mechanism of the present invention, when the liquid passes through the throttle portion provided in the middle of the flow path, the gas dissolved in the liquid is deposited under reduced pressure to generate bubbles. The liquid introduced into the flow path from the liquid inlet needs to increase the flow velocity while reducing the cross-sectional area of the flow path before reaching the throttle portion. On the other hand, as the cross-sectional area of the flow path decreases, the frictional resistance received from the inner surface of the flow path wall also increases, so an increase in flow rate proportional to the cross-sectional reduction rate cannot be expected. Therefore, in the microbubble generation mechanism of the present invention, this problem is solved by configuring the flow path as follows. First, as a result of geometrical necessity by forming the throttle part in the flow path, a region having a larger cross-sectional area than the throttle part is formed on the upstream side of the throttle part. In this specification, this region is referred to as a preparation enlargement unit.

  Then, a cross-sectional area smaller than that of the preparatory enlarged portion is formed at the end on the connection side with the preparatory enlarged portion so that a stepped surface is formed in the circumferential direction with respect to the flow axis in a form adjacent to the upstream side of the preparatory enlarged portion. Thus, a flow introducing portion having a larger cross-sectional area than the throttle portion is formed. In other words, the flow introduction part is connected in a stepped form with a smaller cross-sectional area than the area formed immediately before the throttle part (the area formed just before the throttle part is the flow introduction part. Since the channel cross-sectional area discontinuously expands on the connection side, the name “preparation expansion portion” is given).

  Since the cross-sectional area of the flow path is discontinuously enlarged as described above, a stagnation region having a small flow velocity is formed as a flow buffer space around the connection opening of the flow introduction portion at the upstream end portion of the preparation expansion portion. The outer peripheral portion of the main flow that goes straight from the flow introduction portion into the preparation expansion portion expands in the flow buffer space and swirls in the direction opposite to the main flow to generate a vortex flow. That is, in the flow buffer space, a vortex flow is generated so as to surround the main flow, thereby reducing the pressure loss of the main flow due to friction with the flow path wall surface, and maintaining the liquid flow inside the preparation expansion portion at high speed. Will be able to.

  As a first specific example, the above-mentioned preparation enlarged portion can be formed to have a channel cross-sectional area smaller than the liquid inlet over the entire length in the flow direction. The flow introduction part is formed between the inlet side introduction part connected to the preparation expansion part in a form following the liquid inlet, and between the inlet side introduction part and the preparation expansion part, and flows more upstream than the preparation expansion part on the upstream end side. It can be formed as having a reduced diameter portion that gradually reduces the cross-sectional area toward the preparatory enlarged portion so that the cross-sectional area is large and the flow passage cross-sectional area is smaller than the preparatory enlarged portion on the downstream end side. According to this configuration, the liquid flow increased at the preparation diameter-reducing portion is supplied to the throttle portion via the preparation enlargement portion having a smaller channel cross-sectional area than the liquid inlet. The high-speed liquid flow is reduced in loss due to the vortex flow formed in the flow buffer space of the preparatory expansion section, and is supplied to the throttle section while maintaining a sufficiently high flow rate state. Can be promoted.

  In the above configuration, the flow direction is such that, in the flow path, between the prepared reduced diameter portion and the prepared enlarged portion, the cross-sectional area is larger than the minimum portion of the throttle portion and smaller than the inlet-side introduction portion. It is possible to form a small-diameter portion having a uniform cross-sectional area. The flow of the liquid supplied from the liquid inlet is concentrated toward the throttle part by the preparation reduced diameter part, but is rectified by the preparation diameter small part having a uniform cross-sectional area immediately before reaching the throttle part. In addition, the flow of the liquid passing through the throttle portion can be made high-speed and uniform, and the precipitation and refinement of bubbles can be further promoted. The small preparation diameter portion can be formed to have the same cross-sectional area as the outlet side opening of the preparation reduced diameter portion.

  In the above configuration, it can be said that it is advantageous to maintain the passage flow velocity of the throttle portion at a high speed by not forming an additional cross-sectional reduction portion downstream of the throttle portion. Specifically, a nozzle passage that sucks and introduces gas into the liquid flowing through the throttle portion by the negative pressure generated in the throttle portion can be formed so as to communicate with the throttle portion. By making the flow of the liquid passing through the throttle part high-speed and uniform, the amount of gas sucked into the throttle part can be increased. In this case, the flow path can be formed such that the cross-sectional area of the flow path increases in a constant or monotonous manner in a section extending to the liquid outlet on the downstream side of the throttle portion.

  Next, as a second specific example, the flow introduction part is formed as an inlet side introduction part connected to the preparation expansion part in a form following the liquid inlet, and the preparation expansion part is formed on the connection side with the inlet side introduction part. A reduced diameter portion that has a larger cross-sectional area than the liquid inlet and that gradually decreases the cross-sectional area so that the flow-path cross-sectional area is smaller than the liquid inlet at the downstream end and larger than the throttle portion. Can be formed. By forming the preparation enlargement part itself as a part including a preparation reduced diameter part that gradually decreases the cross-sectional area toward the throttle part, it is possible to smoothly increase the speed of the liquid flow toward the throttle part.

  In addition, the preparation expansion portion has a larger cross-sectional area than the liquid inlet on the connection side with the inlet side introduction portion, so that the flow buffer space formed on the connection side with the flow introduction portion of the preparation expansion portion, and thus the flow buffer. The vortex formed in the space becomes larger and more prominent. As a result, even when a relatively coarse bubble is contained in the liquid flowing in from the liquid inlet, it can be preliminarily pulverized by the vortex generated in the flow buffer space.

  This configuration is particularly effective when a gas is forcibly dissolved in a liquid by pressure dissolution. Specifically, from a pressure dissolution unit that generates a pressurized concentrated gas solution in which the gas concentration is increased by forcibly dissolving the gas in the liquid by mixing the liquid with the liquid and forcibly dissolving the gas. A liquid outflow pipe for allowing the pressurized concentrated gas solution to flow out while reducing the pressure can be provided, and a flow path forming member can be provided on the liquid outflow pipe. By doing in this way, the dissolved gas density | concentration in the liquid supplied to a throttle part is raised by pressure dissolution, and the number formation density of the bubble which precipitates by a cavitation effect can be raised significantly. In this case, in the case of the pressurized concentrated gas solution, the concentration of dissolved liquid in the surroundings when the bubbles are deposited is high, so that the bubbles tend to grow rapidly. However, the above configuration makes it possible to preliminarily pulverize the vortex generated in the flow buffer space, and then to further pulverize the bubbles by entraining in the rapid flow of the constricted portion. Even when the gas solution is used, the bubbles can be sufficiently miniaturized. Also in this case, it is possible to form a preparation diameter small portion having a uniform cross-sectional area between the preparation reduced diameter portion and the narrowed portion and having a flow passage cross-sectional area smaller than the liquid inlet and larger than the throttle portion. it can.

  The inlet side introduction part can be formed in a cylindrical surface, for example. Further, at the rear end of the preparatory enlarged portion, a stepped surface that forms the periphery of the connection side opening of the inlet side introduction portion is formed as a vertical surface perpendicular to the flow axis, and the inner peripheral surface of the preparatory throttle portion is stepped. It can be formed in the shape of an inclined surface that continuously decreases the flow path cross-sectional area from the connection position with the surface toward the throttle portion. The small preparation diameter portion can be formed to have the same cross-sectional area as the outlet side opening of the preparation reduced diameter portion.

  The throttling portion includes a collision member disposed in the flow path and a throttling gap forming section facing the front end of the collision member in the flow path, and bypasses between the outer surface of the collision member and the inner surface of the flow path. A flow path portion was formed, and a narrowing gap was formed between the collision member and the narrowing gap forming portion to allow the liquid flow to pass while being narrowed so as to have a lower flow rate and a higher flow velocity than the bypass flow path portion. It can be configured as having a structure.

  According to said structure, a collision member is provided in a flow path, and the aperture_diaphragm | restriction gap formation part facing the protrusion direction front-end | tip part of a collision member is provided in this flow path. A water bypass channel portion is formed between the outer surface of the collision member and the inner surface of the channel, and a lower flow rate and a higher flow velocity than the water bypass channel portion are provided between the collision member and the throttle gap forming portion. A narrowing gap is formed so that the liquid passes through while narrowing. When a liquid flow is supplied to the throttle portion having such a structure, the liquid flow is throttled by the throttle gap and the flow velocity is increased. The high-speed liquid flow that passes through the gap is released from the gap outlet and forms a negative pressure region on the downstream side of the gap in accordance with Bernoulli's principle, so that dissolved gas in the liquid flow precipitates due to the cavitation (decompression) effect and bubbles Occurs.

  For example, in a method using a known throttling mechanism such as a venturi tube as in Patent Documents 1 and 2, the efficiency of generating turbulent flow for generating a fine vortex is low, and even if the mutual collision probability of bubbles increases, it becomes microbubbles. The grinding itself tends to be difficult to proceed. Unlike solid particles, bubbles in a liquid are likely to be combined even if they collide with each other. In the mechanisms disclosed in Patent Documents 1 and 2, since the generation efficiency of vortex is low, a relatively macro agitation effect is dominant for bubbles in the liquid flow. Further, since the flow velocity of the passing liquid flow is insufficient, the pressure reduction level downstream of the throttle hole is small and the degree of vortex generation is small. Therefore, the amount of bubble precipitation due to cavitation is small, and the bubble crushing due to the vortex flow is difficult to proceed, so that microbubbles cannot be sufficiently formed. After all, in order to obtain sufficiently reduced microbubbles, it is necessary to rely on a method of reducing the bubbles by dissolving the gas itself by circulating the bubbles with a relatively large particle size generated during passage through the throttle mechanism for a long time. Absent. As a result, in order to obtain water containing a high concentration of microbubbles, it is necessary to circulate for a long time while introducing gas, and there is a disadvantage that the production efficiency of water containing microbubbles is poor.

  However, in the above-described configuration, there is no structure in which a flow path portion other than a throttle hole, such as a conventional venturi tube or an orifice, does not exist, but the liquid that hits the collision member between the collision member forming the throttle gap and the flow path Since the water bypass flow path portion for bypassing the flow is formed, the fluid resistance does not increase excessively when the gap passes, and as a result, a liquid flow much faster than the conventional one passes through the throttle gap. As a result, the squeezing gap and the cavitation (decompression) effect downstream thereof are greatly enhanced, and a larger amount of bubbles can be deposited even in a liquid flow having the same dissolved gas concentration.

  In addition, since the passage flow velocity of the throttle gap is increased, a large number of minute vortices are formed over the entire three-dimensional negative pressure region that is formed in a three-dimensional wide-angle area on the downstream side. In addition to this, the liquid flow that hits the collision member and passed through the water bypass flow path portion flows downstream of the collision member, and a violent turbulent flow with a larger flow rate is superimposed on the negative pressure region. . The passing flux of the constriction gap containing the precipitated bubbles is vigorously and randomly stirred three-dimensionally by these two systems of turbulence, and a large number of micro vortices surrounding the precipitated bubbles attempt to draw the bubbles into themselves. , Bubble pulverization is greatly promoted.

  In the throttle portion having the above structure, the bypass flow path portion can be formed only on one side in the flow path when viewed from the liquid flow direction, but the collision member protrudes from the liquid flow direction. By forming detour channel sections on both sides of the direction, the bubble crushing effect is further enhanced by the turbulent flow coming from both sides of the collision member toward the negative pressure area on the downstream side where bubbles are deposited. Can be generated more efficiently, and it is advantageous in obtaining finer microbubbles.

  A decompression cavity can be formed on at least one of the opposing surfaces that form the aperture gap between the collision member and the aperture gap forming portion. That is, the decompression cavity formed on the surface of the collision member or the diaphragm gap forming portion facing the diaphragm gap functions as a stagnation space with a small flow velocity, so that the flow velocity difference with the inside of the diaphragm gap increases, and cavitation (decompression) according to the Bernoulli principle The effect can be remarkably enhanced. As a result, the amount of bubble deposition resulting from dissolved air in the liquid stream increases, and the concentration of microbubbles in the liquid stream can be increased. From the viewpoint of sufficiently securing the negative pressure region, the opening diameter of the decompression cavity is desirably 1 mm or more, and the depth is desirably larger than the opening diameter.

  Further, if the decompression cavity is resonated in the liquid flow, an ultrasonic band resonance wave is generated by the resonance, and cavitation for bubble deposition and bubble crushing by resonance vibration can be further promoted. In the case of forming a cylindrical decompression cavity, the opening diameter should be less than 10 mm (preferably less than 4 mm) and the depth should be opened from the viewpoint of setting the resonance wave band to an ultrasonic band (100 kHz or more). It is preferable to set it approximately equal to or larger than the aperture (preferably approximately an integral multiple of the aperture).

  Next, at least one of the opposing surfaces forming the narrowing gap of the collision member and the narrowing gap forming portion, the narrowing inclined surface that gradually reduces the distance of the narrowing gap from the upstream side to the downstream side on the liquid inflow side. Can be formed as As a result, the confronting distance of the narrowing gap continuously decreases from the narrowing gap inlet toward the back of the gap, so that the liquid flow can be smoothly narrowed toward the back of the gap, reducing the flow loss when passing through the gap. The flow rate can be increased. In addition, at least one of the opposing surfaces forming the aperture gap of the collision member and the aperture gap forming portion is an enlarged inclined surface that gradually increases the aperture gap distance from the upstream side to the downstream side on the liquid outflow side. It can also be formed.

  A liquid flow separation uneven portion can be formed on the outer peripheral surface of the protruding portion in the flow path of the collision member (or an opposing collision member described later). By forming the liquid flow separation uneven part as described above on the outer peripheral surface of the collision member, the liquid flow that flows in the direction of the central axis of the flow path easily gets separated when the liquid flow separation uneven part is overcome. Thus, the turbulence of the liquid flow can be further promoted. The liquid flow separation uneven portion can be a thread formed on the outer peripheral surface of the protruding portion in the flow path of the collision member. The screw thread has a constant inclination angle with respect to a virtual plane whose normal is the axis of the collision member. When a liquid flow flows into the collision member in a direction parallel to the virtual plane, the liquid flow direction To the downstream side of the collision member across a plurality of threads that are inclined with respect to. At this time, the liquid flow separation that contributes to the turbulent flow is particularly likely to occur when the liquid flow crosses the ridge portion of the thread from one valley side to the opposite valley side.

  In order to generate microbubbles at a sufficient level, the throttle gap has a maximum flow velocity of 8 m when the liquid is supplied so that the pressure difference between the liquid inlet and the liquid outlet is 0.2 MPa, for example. / Second or more (the upper limit value is not limited, but it is desirable that the upper limit value at a pressure difference of 0.2 MPa is 50 m / second, for example). In this case, the maximum negative pressure generated in the aperture gap is preferably 0.02 MPa or more (theoretical upper limit is 0.1 MPa). In particular, when the aforementioned vacuum cavity is formed, when the liquid is supplied so that the pressure difference is 0.2 MPa, the entire area of the vacuum cavity is easily maintained in a negative pressure state of 0.02 MPa or more. be able to. Moreover, the negative pressure region formed adjacent to the downstream side of the collision member by the wrapping turbulent flow is maintained in the negative pressure state of 0.02 MPa or more by making the entire area in the decompression cavity into the negative pressure state of the level. Is possible. Both contribute to the remarkable cavitation effect for bubble precipitation. The negative pressure level of the throttle gap, the decompression cavity, or the negative pressure region formed downstream thereof is more preferably 0.05 MPa or more.

  If the liquid is supplied so that the pressure difference becomes 0.2 MPa, for example, under the negative pressure generation condition as described above, in the case of the throttle portion having the above specific configuration, the bubbles contained in the liquid flow ejected from the liquid outlet port Greatly contributes to miniaturization. For example, when a collision member having a circular axial cross section is employed, when water at 10 ° C. is supplied so that the pressure difference is 0.2 MPa, the outer diameter and bypass flow path of the collision member having the circular axial cross section The flow cross-sectional area of the part is preferably adjusted so that the Reynolds number relating to the collision member disposed in the detour channel part is 10,000 or more.

When a collision member having a cylindrical cross section is arranged in a liquid flow, the Reynolds number Re is given by assuming that the outer diameter of the collision member is D, the flow velocity is U, and the kinematic viscosity coefficient of water is ν.
Re = UD / ν (Dimensionless number) (1)
It is known that the flow around the collision member having a cylindrical cross section is turbulent when the Reynolds number Re is 1500 or more, and particularly when the Re is 10,000 or more, the bubbles are finely pulverized by the wraparound turbulence. Since the effect is drastically enhanced, the bubble particle size at the number average value level can be more easily reduced. For example, if the flow cross-sectional area of the bypass channel is adjusted so that the average flow velocity is 8 m / sec or more, the Reynolds number can be adjusted by adjusting the outer diameter of the collision member having a circular axial cross section to 1 to 5 mm. The value of Re can be easily secured to a value of 10,000 or more.

  In particular, the cross-sectional area of the bypass channel is adjusted so that the average flow velocity when supplying water at 10 ° C. at a supply pressure of 0.55 MPa to the liquid inlet is 18 m / sec or more, If the outer diameter of the collision member having a diameter is adjusted to 1 to 5 mm, the Reynolds number Re relating to the collision member arranged in the detour channel portion is a value exceeding 20000. If the maximum flow velocity of the passing liquid flow in the narrowing gap formed by the collision member is 25 m / sec or more, the electrolyte is not positively added to the number average particle diameter of the microbubbles contained in the jetted liquid flow. It can be reduced to a value of 1 μm or less (for example, a value of 1 nm to 500 nm, preferably a value of 1 nm to 100 nm, and more preferably a value of 1 nm to 50 nm), which has been conventionally considered impossible in fresh water. Become. That is, microbubbles that become nanobubble regions at the number average value level can be easily generated without using a complicated and expensive bubble generator. In addition, under the conditions where the above flow rate conditions are satisfied, the negative pressure level in the throttle gap, the decompression cavity, or the downstream negative pressure region can be increased to 0.05 MPa or more, so that microbubbles that can be generated can be generated. Concentration is also greatly increased.

  Next, if the gap between the throttle gaps is reduced in the throttle part having the above-described configuration, the flow rate through the gap is reduced while the amount of water flowing into the detour channel part is increased. Therefore, if the aperture gap interval is reduced within a range where the flow velocity of the aperture gap does not decrease excessively, the effect of miniaturization due to the turbulent flow of microbubbles generated in the aperture gap can be enhanced, and bubbles with a smaller diameter can be generated. . On the other hand, if the gap between the narrowing gaps is increased, the flow resistance in the narrowing gap is reduced, so that the flow rate of the injection can be increased over the entire cross-section of the bypass channel (in this case, the gap interval is set). Depending on the value, the flow velocity in the throttle gap may tend to be slightly insufficient, but it is advantageous when priority is given to securing the injection flow rate). Therefore, if the aperture gap adjusting mechanism for adjusting the aperture gap interval to be variable is provided in the aperture section, the aperture gap interval can be appropriately adjusted according to the required level of the bubble diameter reduction and the injection flow rate. .

  The throttle gap forming portion can be formed as an opposing collision member that protrudes from the inner surface of the wall portion toward the collision member on the side opposite to the collision member with respect to the cross-sectional center of the flow path. And the front-end | tip part of the protrusion direction of an opposing collision member can be formed. For example, the throttle gap may be formed by making the front end surface of the collision member face the inner peripheral surface of the flow path wall. In this case, the portion of the flow path wall that faces the collision member constitutes the throttle gap forming portion. It becomes. However, in this configuration, since the throttle gap is located in the outer peripheral region of the cross section of the flow path shaft where the flow loss due to wall friction is large, the flow velocity through the throttle gap tends to be small. However, by providing an opposing collision member, the formation position of the narrowing gap can be brought closer to the center of the cross section where the flow velocity is large, the passage flow velocity of the narrowing gap is increased, the cavitation effect is enhanced, and microbubbles are generated more efficiently. Can be made.

In addition, a reduced diameter portion having a tapered peripheral side surface that decreases in diameter toward the distal end can be formed at a distal end portion facing at least one throttle gap between the collision member and the opposing collision member. By providing such a reduced diameter portion, the following effects are achieved.
In the vicinity of the outer peripheral surface tip of the reduced diameter portion of the collision member or the opposing collision member, the collision bypass length of the liquid flow is shorter than that near the outer peripheral surface proximal end, and the flow velocity increases. Further, the portion located on the upstream side in the liquid flow direction on the outer peripheral surface of the reduced diameter portion forms the above-described throttle inclined surface. As a result, the effect of generating turbulence near the throttle gap is further enhanced, and the generation efficiency of microbubbles is further improved.
・ Effects of vortex flow or turbulent flow due to the detour of the liquid flow are not only in the plane perpendicular to the opposing direction but also in the plane parallel to the opposing direction (i.e., contraction). This also occurs in the direction of crossing the diameter portion to the narrowing gap side), and the three-dimensional bubble pulverizing effect is further enhanced.

  In the case where the opposing collision member is provided, the above-described decompression cavity that retracts in the gap forming direction can be formed on one or both of the collision member and the opposing collision member at the tip surface facing the throttle gap. In particular, when a configuration is adopted in which a reduced pressure cavity is formed in one of the collision member and the opposing collision member and a reduced diameter portion is formed on the other side so that the tip of the collision member faces the opening of the reduced pressure cavity, the liquid flow in the throttle gap Can significantly increase the speed by the reduced diameter portion. The increased liquid flow comes into contact with the stagnation portion in the decompression cavity, so that a very large flow velocity difference is generated. Moreover, when the diameter of the reduced diameter portion is overcome, the liquid flow is diverted to the decompression cavity side in a bent form, so that the section length in which the flow velocity difference occurs is also increased (this effect is caused by a part of the reduced diameter portion on the tip side being decompressed). This is more noticeable when the position is adjusted to enter the interior of the cavity). Furthermore, as will be described later, there is a possibility that the resonance effect of the decompression cavity can be made more conspicuous by forming this reduced diameter portion. Both contribute effectively to improving the generation efficiency of microbubbles and further miniaturizing the bubble diameter.

  Specifically, the narrowing gap has a wedge-shaped cross section when a peripheral region forming an opening peripheral portion of the decompression cavity and a tapered peripheral side surface of the reduced diameter portion are opposed to each other at the front end surface of the collision member, and An annular gap peripheral space whose outer peripheral side opens to the detour channel portion and a decompression cavity are formed via an annular constriction gap portion formed at a position opposed to the inner peripheral edge of the opening of the decompression cavity and the peripheral side surface of the reduced diameter portion. Therefore, it can be configured to communicate with each other. As a result, portions of the outer peripheral surface of the reduced diameter portion located on both sides of the throttle gap in the liquid flow direction also function as auxiliary gaps. Therefore, the liquid flow that does not pass through the narrowing gap also causes cavitation when passing through the auxiliary gap, thereby contributing to improvement in the generation efficiency of microbubbles.

  In addition, when providing an opposing collision member, it is good to form a detour channel part in the form spanning the outer peripheral surface of a collision member and the outer peripheral surface of an opposing collision member. Thereby, both a collision member and a counter collision member wrap around and contribute to generation | occurrence | production of a turbulent flow, and the pulverization effect of precipitation bubbles improves further.

  Further, when the center of the gap interval at the liquid inflow side opening position of the throttle gap is defined as the gap center, the distance from the inner surface of the flow path wall portion to the gap center in the radial direction of the cross section of the flow path is the distance from the center of the cross section If the aperture gap formation position is adjusted so that the gap center is offset by a predetermined length in the radial direction from the center of the cross section within a range that does not become smaller than that, the generation efficiency of microbubbles in the aperture gap can be further increased. it can.

  Each of the collision member and the opposing collision member has a flow path wall so that the front end side protrudes into the flow path with respect to the flow path wall portion of the flow path forming member and the rear end side is exposed on the outer peripheral surface of the flow path forming member. It can arrange | position in the form which penetrates a part. And the opposing collision member can be set as the structure screwed in the female screw hole penetrated and formed in the flow-path wall part while a male screw part is formed in an outer peripheral surface. Thereby, the space | interval of an aperture gap can be adjusted according to the screwing amount of this opposing collision member in this internal thread hole. In addition, by configuring the collision member as a similar screw member, it is also possible to adjust the position of the narrowing gap in the cross section of the flow path (in particular, the offset amount from the center of the cross section in the radial direction). The male screw portion of the opposing collision member can also be used as the liquid flow separation uneven portion described above.

The schematic diagram which shows one structural example of the liquid production | generation apparatus containing a microbubble using the microbubble generation mechanism of this invention. The top view and cross-sectional view of a bubble miniaturization nozzle. The cross-sectional view which expands and shows the principal part of a bubble miniaturization nozzle. The expanded-axis sectional view of the aperture gap structure formed using a collision member. The cross-sectional view which shows the structure of a gas suction nozzle. Explanatory drawing which shows typically the turbulent flow formation effect | action by a collision member. The figure explaining the concept to which a bubble is torn and miniaturized by a plurality of eddy currents. Explanatory drawing of an effect | action of a collision member and a counter collision member. The figure explaining the concept that a bubble merges by collision. Action explanatory drawing of gap peripheral space. Explanatory drawing of the action of the screw thread on the water flow. The perspective view which shows an example of the collision member which formed the water flow peeling uneven | corrugated | grooved part in serrated form. The simulation image (cross-sectional view) which shows the flow analysis result in a bubble miniaturization nozzle. The simulation image (plan view) which shows the flow analysis result in the bubble miniaturization nozzle. The cross-sectional view which shows the 1st modification of a bubble miniaturization nozzle. The cross-sectional view which shows the 2nd modification of a bubble miniaturization nozzle. The axial sectional view showing the 1st modification of an aperture gap. The axial sectional view which shows the 2nd modification similarly. The axial sectional view which shows a 3rd modification similarly. The axial sectional view which shows the 4th modification similarly. The axial sectional view which shows the 5th modification similarly. The axial sectional view and top view showing the 6th modification similarly. Similarly, an axial sectional view and a transverse sectional view showing a seventh modification. Similarly, an axial sectional view and a transverse sectional view showing an eighth modification. The cross-sectional view which shows the 3rd modification of a bubble miniaturization nozzle.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic diagram showing an example of the configuration of a microbubble-containing liquid generating apparatus using the microbubble generating mechanism of the present invention. The microbubble-containing liquid generating apparatus 1 employs water as a liquid that serves as a bubble introduction medium, and passes through a raw water introduction pipe 372 (provided with a valve 2 that opens and closes the introduction of raw water). The raw water is supplied to the main tank 319. The liquid used as the bubble introduction medium may be other than water depending on the application (for example, fossil fuels such as gasoline, light oil, heavy oil, etc. in addition to alcohol, but are not limited thereto). Not) An air release port 319L is formed on the upper surface of the main tank 319 so that the internal pressure is maintained at atmospheric pressure. Reference numeral 319k denotes a take-out port for taking out water containing fine bubbles from the tank.

  A circulation pipe 313 extends from the main tank 319, and its end is connected to the suction side of the pump 301, and a gas suction nozzle 315 is provided on the way. A gas supply pipe 309 is connected to the gas suction nozzle 315, and a gas serving as a bubble medium is sucked into the gas suction nozzle 315 through the gas supply pipe 309 and mixed and introduced into the liquid passing through the circulation line 313. Is done. On the other hand, a pressurized introduction line 311 extends from the discharge side of the pump 301, and its end is connected to the pressurized dissolution tank 310. The liquid mixed with gas by the gas suction nozzle 315 is pumped to the pressurized dissolution tank 310 by the pump 301. In the pressurized dissolution tank 310, gas and water are pressurized while being mixed, and the gas is forcibly dissolved in water to increase the gas concentration, thereby generating pressurized concentrated gas-dissolved water. In other words, the gas suction nozzle 315 and the pressurized dissolution tank 310 pressurize in a state where the gas and the liquid are in contact with each other, and the pressurized concentrated gas dissolved liquid in which the gas concentration is increased by forcibly dissolving the gas in the liquid. The pressure dissolution unit to be generated is configured.

  A water outflow pipe 312 for allowing the pressurized concentrated gas dissolved water in the pressurized dissolution tank 310 to flow out while reducing the pressure extends from the pressurized dissolution tank 310, and its end is connected to the main tank 319. A bubble miniaturization nozzle 21 configured as a microbubble generating mechanism of the present invention is provided on the water outflow pipe 312, and the pressurized concentrated gas-dissolved water flowing out from the pressure dissolution tank 310 passes through the bubble miniaturization nozzle 21. As a result, water containing microbubbles is returned to the main tank 319. In addition, on the upstream side of the bubble miniaturization nozzle 21 on the water outflow pipe 312, the liquid pressure of the pressurized concentrated gas-dissolved water to the bubble miniaturization nozzle 21 (and thus the internal pressure of the pressure dissolution tank 310) is set. A pressure valve 316 to adjust is provided.

FIG. 2A is a plan view and a cross-sectional view showing a configuration example of the bubble miniaturization nozzle 21. FIG. 2B is an enlarged cross-sectional view showing the main part. The bubble miniaturization nozzle 21 includes a liquid inlet 31 and a liquid outlet 106, and includes a hollow flow path forming member 20 in which a flow path FP from the liquid inlet 31 toward the liquid outlet 106 is formed. In the present embodiment, the flow path FP is formed in a rotating body shape with respect to the central axis O, and the flow direction coincides with the direction of the central axis O. Specifically, the flow path FP includes the following elements.
The throttle portion 21J is formed between the liquid inlet 31 and the liquid outlet 106 in the flow direction, and has a smaller cross-sectional area and a higher flow velocity than both the liquid inlet 31 and the liquid outlet 106. .
-Enlarged portion 151: formed subsequent to the narrowed portion 21J so that the cross-sectional area becomes larger than the narrowed portion 21J. In this embodiment, the enlarged portion 151 is formed as a uniform cross-section having a uniform cross-sectional area in the flow direction, specifically, a cylindrical surface.

Flow receiving portion 152: The flow receiving port 152p has a smaller cross-sectional area than the enlarged portion 151, and the flow receiving port 152p overlaps with the opening of the constricted portion 21J when projected onto a plane orthogonal to the flow direction. The flow is formed following the enlarged portion 151 so as to generate the flow, and the flow discharged from the narrowed portion 21J to the enlarged portion 151 is received by the flow receiving port 152p and guided to the liquid outlet 106. In this embodiment, the flow receiving portion 152 is also formed in a cylindrical surface shape.

Outward flow swirling unit 153: The flow is formed around the flow receiving port 152p, and the outer flow FS flowing along the outer peripheral region of the expanding unit 151 among the flow discharged to the expanding unit 151 is swirled while the expanding unit 151 side is swung. Return to. In this embodiment, the enlarged portion 151 is formed in a cylindrical shape, the flow receiving port 152p is concentrically opened with respect to the enlarged portion 151, and forms the flow receiving portion 152 with the inner peripheral surface of the wall forming the enlarged portion 151. A step portion connecting the inner peripheral surface of the wall portion forms the outward flow swirl portion 153.

Preparation enlarged portion 156: It is formed adjacent to the upstream side of the throttle portion 21J so that the cross-sectional area is larger than that of the throttle portion 21J.
Flow introduction part 150: Connected in the form of forming a stepped surface in the circumferential direction adjacent to the upstream side of the preparation enlargement part 156, and the preparation enlargement part 156 at the connection side end with the preparation enlargement part 156 The cross-sectional area is smaller than that of the narrowed portion 21J.
The outer peripheral region of the preparation expansion unit 156 on the connection side with the flow introduction unit 150 forms a flow buffer space 155 that protects the periphery of the main flow FM that goes straight from the flow introduction unit 150 into the preparation expansion unit 156.

  The flow introducing portion 150 is formed as a cylindrical surface-side inlet-side introducing portion (hereinafter also referred to as the inlet-side introducing portion 150) connected to the preparation expanding portion 156 in a form following the liquid inlet 31, and the preparation expanding portion 156 is connected to the inlet expanding portion 156. The cross-sectional area is larger than that of the liquid inlet 31 on the connection side with the side introduction portion 150, and the flow passage cross-sectional area is smaller than that of the liquid inlet 31 at the downstream end portion and larger than that of the throttle portion 21J. Thus, it has a preliminarily reduced diameter portion 30 that gradually reduces the cross-sectional area. Further, between the prepared diameter-reduced portion 30 and the throttle portion 21J, there is a prepared diameter small portion 157 having a uniform cross-sectional area that has a channel cross-sectional area smaller than the liquid inlet 31 and larger than the throttle portion 21J. Formed.

  At the rear end of the preparatory enlarged portion 156, a stepped surface 156f that forms the periphery of the connection side opening of the inlet side introduction portion 150 is formed as a vertical surface perpendicular to the flow direction, and the inner peripheral surface of the preparatory reduced diameter portion 30 is It is formed in the shape of an inclined surface (here, a conical surface) that continuously decreases the flow path cross-sectional area from the connection position with the stepped surface 156f toward the throttle portion 21J. The small preparation diameter portion 157 is formed to have the same cross-sectional area as the outlet side opening of the preparation reduced diameter portion 30.

In addition, the inner diameter of the inlet side introduction section 150 is D ₁ , the inner diameter of the upstream end of the preparation expansion section 156 is D ₂ , the inner diameter of the preparation diameter small section 157 is D ₃ , and the inner diameter of the expansion section 151 is D ₄ . the inner diameter of the part 152 as _{D 5,}
D ₁ <D ₂ ;
D ₃ <D ₁ ;
D ₄ > D ₃ ;
D ₅ <D ₄ ;
The dimensions of each part are set so that In this embodiment,
D ₂ > D ₄ > D ₁ (= D ₅ )> D ₃
It is set to become.

  Next, the structure of the aperture 21J will be described. The restricting portion 21J includes an restricting gap 21G and a bypass channel portion 251 (FIG. 3). The narrowing gap 21G is formed by the collision member 22 disposed radially inward of the flow path wall 25 in the flow path forming member 20 and the forward end portion of the collision member 22 in the protrusion direction in the flow path FP. And a diaphragm gap forming portion 23 facing each other. As shown in FIG. 3, a detour channel portion 251 is formed between the outer peripheral surface of the collision member 22 and the inner surface of the channel wall portion 25 in the bubble miniaturization nozzle 21. In addition, the narrowing gap 21G is formed between the collision member 22 and the narrowing gap forming portion 23 so as to allow the water flow to pass while being narrowed so as to have a lower flow rate and a higher flow velocity than the bypass flow path portion 251.

  The flow path forming member 20 is made of metal, ceramic, or resin. As shown in FIG. 2A, the narrowing gap forming portion 23 is a counter-collision member (hereinafter referred to as counter-collision) that protrudes from the inner surface of the wall portion toward the collision member 22 on the side opposite to the collision member 22 with respect to the cross-sectional center O of the flow path FP. The diaphragm gap 21G (FIG. 3) is formed between the protruding end of the collision member 22 and the protruding end of the opposing collision member 23. Both ends of the flow path forming member of the bubble miniaturization nozzle 21 can be connected to the front and rear pipes by, for example, one-touch joints (however, other connection structures such as screw joints may be adopted).

  Each of the collision member 22 and the opposing collision member 23 is configured as a screw member made of metal (for example, stainless steel: for example, SUS316 material), and both of the front end side protrudes into the flow path FP with respect to the flow path wall portion 25, and It arrange | positions in the form which penetrates this flow-path wall part 25 so that an end side may be exposed to the outer peripheral surface of the flow-path wall part 25. FIG. A male threaded portion 22t is formed on the outer peripheral surface of the collision member 22, and is screwed into a female threaded hole 22u formed through the flow path wall 25. The interval of the aperture gap 21G can be adjusted according to the amount of screwing of the collision member 22 in the female screw hole 22u. A male threaded portion 23t is also formed on the outer peripheral surface of the opposing collision member 23, and is screwed into a female threaded hole 23u formed through the flow path wall 25. The interval of the throttle gap 21G can be adjusted according to the amount of screwing of the opposing collision member 23 in the female screw hole 23u. Further, if both the collision member 22 and the counter collision member 23 are screwed in the same direction, the position of the throttle gap 21G in the radial direction of the axial cross section of the flow path FP can be changed. In order to facilitate the adjustment of the screwing of these members, a tool mechanism that engages a tool such as a hexagon wrench with each head end surface of the collision member 22 and the opposing collision member 23 that protrudes outside the flow path wall portion 25. Joint holes 222 and 232 are respectively formed. Further, sleeves 22 </ b> S and 23 </ b> S for projecting the outer end portions of the collision member 22 and the opposing collision member 23 are formed on the outer peripheral surface of the flow path forming member 20.

  When adjustment is not particularly performed with the interval or position of the aperture gap 21G being fixed, the collision member 22 and the opposing collision member 23 are fixed and integrated with the flow path wall 25 so as not to be screwed by insert molding or the like. It is also possible to configure. Furthermore, only one of the collision member 22 and the opposing collision member 23 can be screwed, and the other can be fixed and integrated with the flow path wall portion 25 so as not to be screwed.

  As shown in FIG. 3, the collision member 22 is formed with a decompression cavity 221 that is retracted in the gap forming direction at the tip surface facing the throttle gap 21G. Further, the opposing collision member 23 is formed with a reduced diameter portion 23k in such a positional relationship that the tip faces the opening of the decompression cavity 221 (however, the opposing collision member 23 is formed with a reduced pressure cavity and the collision member 22 has a reduced diameter. Part may be formed). The reduced diameter portion 23k formed on the opposing collision member 23 has a tapered peripheral side surface 231 (specifically, a conical surface) that decreases in diameter toward the tip. A portion of the tapered peripheral side surface 231 located on the water inflow side (upstream side of the flow) forms a throttle inclined surface that gradually reduces the interval of the throttle gap 21G from the upstream side toward the downstream side. Moreover, the part located in the water outflow side (flow downstream) comprises the expansion inclination surface which expands gradually the space | interval of the aperture gap 21G toward the downstream from the upstream. The collision member 22 and the opposing collision member 23 are disposed concentrically. The decompression cavity 221 has a cylindrical inner peripheral surface that is concentric with the outer peripheral surface of the collision member 22. Further, the position of the reduced diameter portion 23k is adjusted in the axial direction so that a part of the distal end side enters the inside of the decompression cavity 221.

  The narrowing gap 21G has an annular shape having a wedge-shaped cross section when the peripheral region 224 forming the opening peripheral portion of the decompression cavity 221 and the tapered peripheral side surface 231 of the reduced diameter portion 23k are opposed to each other at the front end surface of the collision member 22. A gap peripheral space 251n is formed. The space outer peripheral side of the gap peripheral space 251n is opened to the bypass flow path portion 251, and an annular constriction gap portion 21n formed at an opposing position between the inner peripheral edge of the decompression cavity 221 and the peripheral side surface of the reduced diameter portion 23k. And a structure communicating with the decompression cavity 221 through each other. The detour channel portion 251 spans the outer peripheral surface of the collision member 22 and the outer peripheral surface of the opposing collision member 23 on both sides in the flow direction of the collision member 22 when viewed from the water flow direction in the flow channel FP. Is formed.

  Further, as shown in FIG. 2B, the enlarged portion 151 formed on the downstream side of the throttle portion 21J has an upstream end thereof in the flow direction from the axial cross-sectional center λ of the collision member 22 (and the opposing collision member 23). Is also formed so as to overlap with a portion located on the front side.

Next, FIG. 4 is a cross-sectional view showing the internal structure of the gas suction nozzle 315 (components that are conceptually common to the bubble miniaturization nozzle 21 are given the same reference numerals). The gas suction nozzle 315 is also made of metal, ceramic or resin, and includes a hollow flow path forming member 20 in which a flow path FP from the liquid inlet 31 to the liquid outlet 106 is formed. Specifically, the flow path FP includes the following elements.
The throttle portion 21J is formed between the liquid inlet 31 and the liquid outlet 106 in the flow direction, and has a smaller cross-sectional area and a higher flow velocity than both the liquid inlet 31 and the liquid outlet 106. .
Preparation enlarged portion 156: It is formed adjacent to the upstream side of the throttle portion 21J so that the cross-sectional area is larger than that of the throttle portion 21J.
Flow introduction part 150: Connected in the form of forming a stepped surface in the circumferential direction adjacent to the upstream side of the preparation enlargement part 156, and the preparation enlargement part 156 at the connection side end with the preparation enlargement part 156 The cross-sectional area is smaller than that of the narrowed portion 21J.
The outer peripheral region of the preparation expansion unit 156 on the connection side with the flow introduction unit 150 forms a flow buffer space 155 that protects the periphery of the main flow that goes straight from the flow introduction unit 150 into the preparation expansion unit 156.

The preparation enlarged portion 156 (inner diameter d ₂ ) is formed to have a smaller channel cross-sectional area than the liquid inlet 31 (inner diameter d ₁ ). The flow introduction part 150 is formed between the inlet side introduction part 25L connected to the preparation enlargement part 156 in a form following the liquid inlet 31, and between the inlet side introduction part 25L and the preparation enlargement part 156, and is connected to the upstream end side. The prepared enlarged portion 156 has a flow passage cross-sectional area larger than that of the prepared enlarged portion 156 at (inner diameter d ₁ ) and smaller than that of the prepared enlarged portion 156 at the downstream end (inner diameter d ₀ ). And a preliminarily reduced diameter portion 30 that gradually reduces the cross-sectional area. Further, the gap between the prepared reduced diameter portion 30 and the prepared enlarged portion 156 is cut in the flow direction so as to have a larger cross-sectional area than the minimum portion of the narrowed portion 21J and a smaller cross-sectional area than the inlet-side introduction portion 25L. A prepared diameter small portion 157 (inner diameter d ₀ ) having a uniform area is formed. The prepared small diameter portion 157 forms the flow introducing portion 150 together with the prepared reduced diameter portion 30, and is formed in a cylindrical surface shape here as having the same cross-sectional area as the outlet side opening of the prepared reduced diameter portion 30. ing.

  Further, a nozzle passage 226 that sucks and introduces gas into the liquid flowing through the throttle portion 21J due to the negative pressure generated in the throttle portion 21J is formed in communication with the throttle portion 21J. The channel FP has a constant channel cross-sectional area in the section 26 extending to the liquid outlet 106 on the downstream side of the restricting portion 21J, and is formed in a cylindrical surface here. The preparatory enlarged portion 156 is formed in a cylindrical surface shape so as to coincide with the extended surface of the section 26 on the narrowed portion 21J side.

  The formation form of the restricting portion 21J of the gas suction nozzle 315 will be described with reference to FIG. 3 in that the restricting gap 21G and the bypass flow passage portion 251 (FIG. 3) are formed using the collision member 22 and the opposing collision member 23. This is exactly the same as the narrowed portion 21J of the bubble miniaturized nozzle 21. Hereinafter, only the differences will be described in detail, and descriptions of common parts will be omitted.

  That is, a nozzle passage 226 is formed in the collision member 22 in the gas suction nozzle 315. The nozzle passage 226 penetrates the collision member 22 (as a result, the flow path wall portion 25) in the protruding direction into the flow path FP, and one end side of the nozzle passage 226 is the throttle gap 21G at the front end side of the collision member 22. The gas injection port 226d is opened in the inside, and the other end side is formed so as to penetrate the flow path wall portion 25 and open the gas intake port 226e on the outer surface of the wall portion (the tool engagement hole 222 and the decompression cavity described above). 221 can also be seen as forming part of the nozzle passage). The sleeve 22S for accommodating the collision member 22 is formed with a gas supply hole 309J penetratingly formed at a position outside the end surface of the collision member 22 in the sleeve 22S, and the gas supply pipe 309 is connected thereto. . In the sleeve 22S, the opening of the accommodation hole of the collision member 22 formed in the axial direction is sealed with a cap 22C. The type of gas supplied to the gas supply pipe 309 is not particularly limited, but is, for example, air, oxygen, ozone, carbon dioxide, hydrogen, etc., and one or more of them, or further dilution A mixed gas with a gas (for example, nitrogen, argon, etc.) can be used. When these gases are supplied to the gas inlet 226e of the nozzle passage 226 through the gas supply pipe 309, the gas is sucked and taken in through the nozzle passage 226 by the negative water flow pressure generated in the throttle gap 21G. It ejects from the ejection hole 226d into the aperture gap 21G.

  As shown in FIG. 4, a connecting female thread portion 274 is formed on the outer peripheral surface on the downstream side of the flow path forming member 20. Further, a connecting female thread portion 278u is formed on the inner peripheral surface on the upstream side. The flow path forming member 20 is connected to the pipe by screwing at the connecting male screw portion 274 and the connecting female screw portion 278u. Note that the flow path connecting portion is not limited to the threaded portion, and other known pipe connecting structures such as a one-touch joint may be adopted as long as the necessary pressure resistance can be secured.

  Hereinafter, the operation of the microbubble-containing liquid generating apparatus 1 of FIG. 1 will be described. First, the valve 2 is opened, and the pump 301 is operated while supplying raw water into the main tank 319. The pump 301 sucks the raw water from the main tank 319 through the gas suction nozzle 315. As shown in FIG. 4, when the raw material water passes through the gas suction nozzle 315, the flow is reduced by the preparation reduced diameter portion 30 and the flow velocity is increased, and then the preparation water passes through the preparation diameter small portion 157 and the preparation enlarged portion 156. It is supplied to the diaphragm unit 21J.

  The prepared diameter small portion 157 and the prepared enlarged portion 156 that form the end of the flow introducing portion 150 discontinuously increase the cross-sectional area by forming a stepped surface at the connection position between them. As the cross-sectional area of the flow path expands discontinuously as described above, a stagnation region with a low flow velocity is formed as a flow buffer space 155 around the connection opening of the preparation diameter small portion 157 at the upstream end of the preparation expansion portion 156. It is formed. The outer peripheral portion of the main flow FM that goes straight from the preparation diameter small portion 157 into the preparation expansion portion 156 spreads in the flow buffer space 155 and swirls in the direction opposite to the main flow FM to generate a vortex flow SW. That is, in the flow buffer space 155, the vortex SW is generated so as to surround the periphery of the main flow FM, thereby reducing the pressure loss of the main flow FM due to friction with the flow path wall surface.

  In other words, the liquid flow increased in speed by the preparatory diameter reducing unit 30 is supplied to the throttle unit 21J via the preparatory enlargement unit 156 having a smaller channel cross-sectional area than the liquid inlet 31, but the high-speed liquid flow is prepared and enlarged. Loss is reduced by the eddy current SW formed in the flow buffer space 155 of the portion 156 and is supplied to the throttle portion 21J in a state where the high flow rate state is sufficiently maintained, so that the gas to the throttle portion 21J via the nozzle passage 226 The amount of suction can be increased. Note that, in the channel FP, the entire section 26 extending to the liquid outlet 106 on the downstream side of the throttle portion 21J is formed in a cylindrical surface shape having a constant channel cross-sectional area. That is, no additional cross-sectional reduction portion is formed downstream of the throttle portion 21J, and consideration is given to maintaining the passage flow velocity of the throttle portion 21J at a high speed.

  As shown in FIG. 3, the restricting portion 21J employs a unique structure in which the restricting gap 21G and the bypass flow passage portion 251 are combined by the impact member 22 and the opposing impact member 23. The fine pulverization of bubbles formed by gas suction proceeds remarkably. The specific action will be described in detail when the bubble miniaturization nozzle 21 that adopts the same narrowing gap structure is described.

  Returning to FIG. 1, the gas thus supplied is efficiently refined in the gas suction nozzle 315, becomes water containing fine bubbles, and is pumped to the pressurized dissolution tank 310 by the pump 301. On the outlet side of the pressurized dissolution tank 310, that is, the liquid outflow amount is limited by the pressure valve 316 provided on the water outflow pipe 312, so that water containing microbubbles is pumped into the pressurized dissolution tank 310. As the liquid level rises, the pressure in the tank rises, and the dissolution of the gas supplied in the bubble state proceeds to produce a pressurized concentrated gas solution. The amount of dissolved gas increases as the pressure in the tank increases, but when the amount of liquid flowing into the pressurized dissolution tank 310 via the pressurized introduction pipe 311 and the amount of liquid flowing out of the pressure valve 316 become equal. The rise of the liquid level in the pressurized dissolution tank 310 is stopped, and the internal pressure becomes substantially constant. The tank internal pressure that governs the amount of gas dissolved in the liquid can be determined by the opening of the pressure valve 316.

  The pressurized concentrated gas solution flowing out from the pressurized dissolution tank 310 through the pressure valve 316 to the water outflow pipe 312 flows into the bubble miniaturization nozzle 21 in FIG. 2A while being decompressed. As shown in FIG. 2B, in this case as well, the end of the inlet side introduction portion 150 and the preparation reduced diameter portion 30 forming the preparation enlarged portion 156 are discontinuously disconnected by forming a stepped surface 156f at the connection position between them. Increase area. As a result, a flow buffer space 155 is formed around the connection opening of the inlet side introduction portion 150 at the upstream end portion of the preliminarily reduced diameter portion 30, and a larger and more remarkable eddy current SW is generated. The generation of the vortex SW reduces the pressure loss of the main flow FM due to friction with the flow path wall surface, and even if the supersaturated gas dissolved under pressure is precipitated as relatively coarse bubbles, The swirl flow SW generated in the buffer space 155 can be preliminarily pulverized. In the case of pressurized concentrated gas-dissolved water, since the concentration of dissolved liquid around the bubble is high, the bubble tends to grow rapidly. However, the air bubbles can be further finely pulverized by preliminarily pulverizing the vortex generated in the flow buffer space 155 and then entraining the vortex in the rapid flow of the throttle portion 21J.

  Thus, the water flow speed-up by the preliminarily reduced diameter portion 30 and the coarse bubbles preliminarily pulverized is supplied to the throttle portion 21J. As shown in FIGS. 7B and 7C, a water flow negative pressure is generated in the throttle gap 21G, and dissolved gas is precipitated by the cavitation effect, and bubbles BM are precipitated in the gap passing water flow WF. On the other hand, in FIG. 3, not all of the water flow is supplied to the throttle gap 21G, and a corresponding portion collides with the collision member 22 and detours toward the detour channel portion 251. As shown in FIG. 5, this detouring water flow forms a wraparound turbulent flow CF that wraps around the downstream side of the collision member 22 while generating a large number of small vortex flows SWE three-dimensionally. The precipitated bubbles BM formed in the gap passing water flow WF are entangled in the wraparound turbulent flow CF and pulverized into the micro bubbles BF.

  As described above, by forming the throttle gap 21G using the collision member 22, not only the negative pressure is generated in the throttle gap 21G, but also the collision member 22 collides at a high speed and wraps downstream, thereby causing severe disturbance. A flow is generated three-dimensionally, whereby a large number of small vortex flows can be formed densely in the region immediately downstream of the restricting gap 21G. As shown in FIG. 7A, the flow WF of the pressurized concentrated gas solution is increased by, for example, about 10 to 20 m / second by passing through the preliminarily reduced diameter portion 30 (FIG. 2A). Flow towards the. On the other hand, as shown in FIG. 3, the collision member 22 and the opposing collision member 23 that form the throttle gap 21G form a detour channel portion 251 that detours the water flow WF that collides with the channel wall portion. Yes. That is, since the outer peripheral edge of the throttle gap 21G is open to the detour channel portion 251, the fluid resistance at the time of passing through the gap does not increase excessively. As a result, the water flow WF in the throttle gap 21G is, for example, 25 m / It can pass at high speeds exceeding seconds. As a result, a strong negative pressure region is generated in the narrow gap 21G and a wide region downstream thereof, so that dissolved gas contained in the flow WF is precipitated and a large amount of bubbles BM are generated.

  The throttle gap 21G has a maximum liquid flow velocity of 8 m / sec or more when the liquid is supplied so that the pressure difference between the liquid inlet 31 and the liquid outlet 106 is, for example, 0.2 MPa (the upper limit is not limited). However, it is desirable that the upper limit possible at a pressure difference of 0.2 MPa is adjusted to be, for example, 50 m / sec. In this case, the maximum negative pressure generated in the aperture gap is preferably 0.02 MPa or more (theoretical upper limit is 0.1 MPa). In particular, when the pressure reducing cavity 221 is formed in the collision member 22, when the liquid is supplied so that the pressure difference becomes 0.2 MPa, the entire area of the pressure reducing cavity 221 is in a negative pressure state of 0.02 MPa or more. Can be easily maintained. In addition, since the entire region of the decompression cavity 221 is in the negative pressure state at the level, the negative pressure region formed adjacent to the downstream side of the collision member 22 by the wraparound turbulent flow is also maintained in a negative pressure state of 0.02 MPa or more. It becomes possible to do. Both contribute to the remarkable cavitation effect for bubble precipitation. The negative pressure level of the negative pressure region formed on the narrowing gap 21G or the decompression cavity 221 or downstream thereof is more preferably 0.05 MPa or more.

  If the liquid is supplied so that the pressure difference becomes 0.2 MPa, for example, under the negative pressure generation condition as described above, in the case of the throttle portion having the above specific configuration, the bubbles contained in the liquid flow ejected from the liquid outlet port Greatly contributes to miniaturization. For example, when the collision member 22 having a circular axial section is adopted, when water at 10 ° C. is supplied so that the pressure difference becomes 0.2 MPa, the outer diameter and the detour of the collision member 22 having the circular axial section are bypassed. The flow cross-sectional area of the flow path portion 251 is preferably adjusted so that the Reynolds number relating to the collision member disposed in the detour flow path portion is 10,000 or more.

When the collision member 22 having a cylindrical cross section is disposed in the liquid flow, the Reynolds number Re is given by assuming that the outer diameter of the collision member is D, the flow velocity is U, and the kinematic viscosity coefficient of water is ν.
Re = UD / ν (Dimensionless number) (1)
It is known that the flow around the collision member 22 having a cylindrical cross section is turbulent when the Reynolds number Re is 1500 or more, and particularly when Re is 10,000 or more, the flow of bubbles due to wraparound turbulence The pulverizing effect is greatly enhanced. For example, if the flow cross-sectional area of the bypass channel is adjusted so that the average flow velocity is 8 m / sec or more, the Reynolds number can be adjusted by adjusting the outer diameter of the collision member having a circular axial cross section to 1 to 5 mm. The value of Re can be easily secured to a value of 10,000 or more.

  In particular, the flow cross-sectional area of the detour channel portion 251 is adjusted so that the average flow velocity when the water at 10 ° C. is supplied to the liquid inlet 31 at a supply pressure of 0.55 MPa is 18 m / sec or more. If the outer diameter of the collision member 22 having a cross section is adjusted to 1 to 5 mm, the Reynolds number Re related to the collision member 22 arranged in the detour channel portion 251 becomes a value exceeding 20000.

  Thus, as shown in FIG. 5, the water flow WF that has collided with the collision member 22 and passed through the detour channel portion 251 circulates downstream of the collision member 22, and has a large flow rate that is assumed from the Reynolds number Re level. A violent turbulent CF is formed. Thereby, on the downstream side of the collision member 22, a minute vortex SWE (turbulent flow) is formed at a very high density over the entire area. Further, since the generation density of the eddy current SWE is increased, the negative pressure region is formed not only inside the throttle gap 21G but also on the downstream side thereof so as to widen in a three-dimensional wide angle. Therefore, as shown in FIG. 7C, the passing flow of the constricted gap 21G including the precipitated bubbles BM is agitated by a large number of vortex flows while continuing bubble precipitation in the negative pressure region on the downstream side of the gap. . Further, as shown in FIG. 9 (the JJ cross section in FIG. 5), the peripheral region of the narrowing gap 21G has a wedge-shaped cross section, and an annular gap peripheral space in which the outer peripheral side of the space is open to the detour channel portion 251. 251n are formed, and in particular, portions of the outer peripheral surface of the reduced diameter portion 23k located on both sides of the throttle gap 21G with respect to the direction of the water flow WF also function as auxiliary gaps. Therefore, cavitation also occurs in the water flow passing through the auxiliary gap, and the generated bubble BM is caught in the vortex SWE on the outlet side and pulverized, so that the generation efficiency of microbubbles is further improved.

  The individual vortex flow SWE generated by turbulent flow has a lower pressure at the center than at the outer periphery of the vortex, and therefore acts to draw the flow around the vortex flow SWE into the vortex center. Under the turbulent flow, as described above, a large number of fine eddy currents SWE are densely formed three-dimensionally. As shown in the upper part of FIG. 6, the bubble BM precipitated and grown by the cavitation effect at the time of passing through the throttle gap is A three-dimensional coordination by a plurality of eddy currents SWE is always received. Since each vortex SWE applies a suction force to the bubble BM toward the center of the bubble BM, as shown in the lower part of FIG. 6, the bubble BM is sucked in all directions by the surrounding vortex SWE. In this state, crushing into microbubbles BF is promoted and the bubble diameters are averaged. In other words, rather than colliding the precipitated bubbles BM with each other and pulverizing them, the image is surrounded by a large number of small eddy currents SWE each having a suction force and teared in a plurality of different directions. In addition, since the negative pressure region is greatly extended to the downstream side of the gap, it is possible to expect an effect that the bubble particles grown to a certain level or more are expanded by the negative pressure and burst to be miniaturized.

  Further, as shown in FIG. 10, the outer peripheral surface of the collision member 22 (or the opposing collision member 23) is a male screw portion 22t (23t) in this embodiment, but the outer peripheral surface of each member is a smooth cylindrical surface. The fact that it is a threaded surface contributes to increasing the efficiency of turbulent flow generation. That is, since the collision member 22 or the opposing collision member 23 is erected in a positional relationship in which the central axis is substantially perpendicular to the water flow direction, the screw thread (water flow unevenness portion) 22m formed on the outer peripheral surface It has a certain inclination angle φ (for example, 2 ° or more and 15 ° or less) with respect to the virtual plane VP having the normal of the member axis. When the water flow WF flows toward the collision member in a direction parallel to the imaginary plane VP, the water flow WF crosses the plurality of screw threads 22m inclined with respect to the water flow direction and flows downstream of the collision member. At this time, when the water flow WF gets over the ridge line portion 22b of the thread from one valley side to the opposite valley side, water flow separation that contributes to turbulence is likely to occur. In addition, as shown in FIG. 11, it is also possible to form a water flow peeling uneven | corrugated | grooved part as a serration part 22S along the axial direction of the collision member 22 (or opposing collision member 23).

Further, an important point in this embodiment is that a pressure reducing cavity 221 is formed at the tip of the collision member 22 so as to face the throttle gap 21G. The following actions and effects can be expected from the decompression cavity 221.
-The inside of the decompression cavity 221 is in a high negative pressure region, and bubble precipitation by cavitation is promoted, and bursting due to expansion of the precipitated bubble is likely to occur, which contributes to miniaturization of the bubble.

An ultrasonic band resonance wave is generated by the resonance of the decompression cavity 221 in the water flow, and cavitation for bubble deposition and bubble crushing by resonance vibration are promoted. The following mechanisms can be considered as factors. As shown in FIG. 7, since the tip of the opposing collision member 23 facing the decompression cavity 221 is reduced in diameter, the water flow that runs along the tip is, for example, at a high speed exceeding 30 m / second in the decompression cavity 221. , And multiple reflection is repeated between the inner wall surfaces of the decompression cavity 221. Due to the multiple reflection of the water flow, an ultrasonic band resonance wave is excited at a natural frequency determined from the shape of the decompression cavity 221. For example, assuming that the inner diameter dx of the decompression cavity 221 is 2 mm and the sound velocity c in water is 1500 m / second, the natural frequency of vibration in the cavity radial direction is considered to be almost an integral multiple of c / 2dx although it is a somewhat rough approximation. (Acoustics engineering theory (by Satoshi Ito, 1955) p. 270-271, Corona). Thereby, the frequency of the lowest order vibration can be calculated to be about 375 kHz, and it is understood that the vibration is an ultrasonic band.

  The throttle gap 21G having the above-described structure is also provided in the gas suction nozzle 315. However, in the pressure inflow side bubble miniaturization nozzle 315, the gas sucked from the nozzle passage 226 becomes bubbles and enters the water flow. This is quickly pulverized in the throttle gap 21G by the same mechanism as the above-described bubble miniaturization nozzle 21, that is, by the action of the wraparound turbulent flow CF and the decompression cavity 221. Further, by opening the nozzle passage 226 into the decompression cavity 221, there is an effect that the outside air suction force is enhanced by the large negative pressure in the decompression cavity 221. Further, when the water reaching the narrowing gap 21G contains dissolved gas as in the case where the water containing fine bubbles is circulated and supplied, the dissolved gas is precipitated just like the bubble miniaturizing nozzle 21. Bubbles BM are generated, and they are wrapped around the turbulent flow CF and crushed into micro bubbles.

  Next, when the pressurized concentrated gas-dissolved water dissolves the gas into the supersaturated region at normal pressure, coarse bubbles may remain even after passing through the throttle gap 21G. Therefore, in the bubble miniaturization nozzle 21 of FIG. 2A, such residual coarse bubbles are effectively pulverized by a specific flow element provided on the downstream side of the throttle portion 21J. That is, as shown in FIG. 2B, the flow discharged from the narrowed portion 21J to the enlarged portion 151 spreads outward in the enlarged portion 151 and generates an outward flow FS that flows along the outer peripheral area of the enlarged portion 151. An outer flow swirling portion 153 that swirls the outer flow FS radially inward is formed around the flow receiving port 152p based on the cross-sectional area difference between the enlarged portion 151 and the flow receiving portion 152. Thus, the swirling outward flow flows back into the enlarged portion 151 together with bubbles while winding. As a result, the bubbles contained in the liquid remain in the enlarged portion 151 together with the vortex and can be sufficiently pulverized by being vigorously stirred.

  FIG. 12 (cross-sectional view) and FIG. 13 (plan view) show the flow in the flow path of the bubble miniaturized nozzle 21 having the shape shown in FIG. 2A by using commercially available thermal fluid analysis software (EFD.Lab, Structural Planning Co., Ltd.). The simulation result analyzed using a laboratory is shown. The arrows in the image indicate the direction of the flow at each location, and the flow speed is indicated by the brightness of the arrow (the higher the brightness, the higher the flow speed). The pressure difference applied between the liquid inlet 31 and the liquid outlet 106 is 0.2 MPa. First, on the upstream side of the throttle portion 21J, in the flow buffer space 155 of the preparatory diameter reducing portion 156 that forms the preparatory expansion portion, the main flow FM is regulated by the stepped surface 156f on the rear end side of the preparatory diameter reducing portion 156. It can be seen that a vortex swirl swirling in a tangential direction is generated around the axis of the main flow FM. Due to the effect of reducing the flow loss due to the vortex SW, the main flow FM flows into the constricted portion 21J via the preparation diameter small portion 157 at a high speed exceeding 20 m / sec. It has been confirmed from the simulation results that the flow velocity at the aperture gap 21G greatly exceeds 25 m / sec.

  As shown in FIG. 12, in the enlarged portion 151 formed on the downstream side of the narrowing gap 21G, the direction in which the narrowing gap 21G is formed (that is, the facing direction between the collision member 22 and the opposing collision member 23) is the vertical direction in the drawing. When defined, the flow is directed downward (opposite collision member 23 side) immediately after the narrowing gap 21G, and after reaching the lower surface of the enlarged portion 151, flows along the lower surface in the forward direction toward the rear end side of the enlarged portion 151. Therefore, a large swirl flow SW2 that swirls upward by the outward flow swirl 153 formed in a step shape and flows in the reverse direction along the upper surface of the enlargement 151 toward the constriction gap 21G is the internal space of the enlargement 151. It can be seen that it is formed in a form that fully utilizes. Further, the upstream end of the swivel flow SW2 is formed so that the upstream end of the enlarged portion 151 overlaps with the portion located in front of the axial cross-sectional center of the collision member 22 in the flow direction. It can also be seen that the upstream edge of the swirl flow SW2 is closer to the restriction gap 21G by entering the overlapping region. Thereby, a large amount of bubbles ejected from the narrowing gap 21G can be taken into the swirl flow SW2 more effectively, and the effect of finely crushing the bubbles is enhanced. As shown in FIG. 13, the swirl flow SW2 is paired on both sides with respect to the central axis of the collision member 22 corresponding to the bypass flow path portions 251 (FIG. 3) formed on both sides of the throttle gap 21G. It can also be seen that it has occurred.

  Hereinafter, various modifications of the bubble miniaturization nozzle will be described (elements common to those already described are given the same reference numerals and detailed description thereof will be omitted). The configuration of the bubble miniaturization nozzle 21 shown in FIG. 14 is substantially the same as the configuration of FIG. 2A, but the stepped surface 153 r that forms the outward flow swirl 153 and the outer peripheral edge of the rear end portion of the prepared reduced diameter portion 30. The cross-sectional shape of 155r is formed in a curved shape (that is, a rounded shape). As a result, the swirling flow becomes smoother, the flow velocity of the swirling flow is increased, and the effect of finely crushing the bubbles is enhanced.

  FIG. 15 shows a configuration in which the inner diameter of the enlarged portion 151 is matched with the inner diameter of the flow receiving portion 152 and the outward flow swirl portion is omitted. Although the outer flow swirl portion is omitted, the configuration upstream of the throttle portion 21J is exactly the same as in FIG. 2B, and the flow velocity improvement effect by the flow buffer space 155 and the bubble pulverization effect can be similarly enjoyed. Not too long.

  Hereinafter, various modifications for forming the aperture gap will be described. FIG. 16 shows an example in which the bottom of the cavity is formed in a curved surface in order to make the water flow in the decompression cavity 221 formed in the collision member 22 smoother. FIG. 17 shows an example in which the opening inner peripheral surface of the decompression cavity 221 is a counterbore tapered surface 1224 corresponding to the tapered peripheral side surface 231 of the tip of the opposing collision member 23. By forming the tapered surface 1224, the effect of guiding the water flow to the tip side of the opposing collision member 23 is enhanced.

  FIG. 18 shows an example in which the decompression cavity 221 is omitted from the collision member 22 and the tip surface is formed flat. A tapered peripheral side surface 231 is formed at the distal end portion of the opposing collision member 23, but the distal end surface facing the collision member 22 is formed flat. FIG. 19 shows an example in which a shallow decompression cavity 1232 is formed on the front end surface of the opposing collision member 23. The collision member 22 is not formed with a decompression cavity, and the outer peripheral edge of the tip is a tapered peripheral side surface 225. FIG. 20 shows an example in which the collision member 22 and the opposing collision member 23 are integrally connected in the axial direction by the constriction connecting portion 21C, and the constriction gap 21G 'is formed through the constriction connecting portion.

  FIG. 21 shows that neither the collision member 22 nor the opposing collision member 23 is formed with a decompression cavity, a narrowing gap 21G is formed between the flat opposed surfaces, and the axis of both members is the cross section of the flow path forming member 20. An example in which the detour channel portion 251 is formed only on one side of the collision member 22 (and the opposing collision member 23) is shown by being arranged close to one side with respect to the center.

  Furthermore, FIG. 22 is an example in which the opposing collision member is eliminated and the diaphragm gap 21G is formed in such a manner that the collision member 22 is opposed to the inner surface of the flow path forming member 20 as the throttle gap forming part 20c. The front end surface of the collision member 22 has a convex curved surface corresponding to the inner surface of the wall portion of the flow path forming member 20. FIG. 23 shows an example in which the opposing collision member 123 is formed so as to be wider than the collision member 22 so that the detour channel portion 251 is not formed on the side of the opposing collision member 123.

  FIG. 24 shows an example in which the aperture 21Q is formed as a normal venturi-type aperture mechanism.

1 Microbubble-containing liquid generator 21 Bubble miniaturization nozzle (microbubble generation mechanism)
21J Constriction part 21G Constriction gap 21n Constriction gap part 22 Collision member 22t, 23t Male thread part 22m Screw thread (water flow separation convex part)
22u, 23u Female screw hole 23 Opposing collision member (diaphragm gap forming portion)
23k Reduced diameter part 30 Prepared reduced diameter part FP flow path 31 Liquid inlet 106 Liquid outlet 150 Flow introducing part 151 Enlarged part 152 Flow receiving part FM Main flow FS Outer flow 153 Outer flow swirl part 155 Flow buffer space 156 Prepared enlarged part 157 Preparation diameter small portion 221 Depressurization cavity 226 Nozzle passage 231 Tapered circumferential side surface (aperture inclined surface, enlarged inclined surface)
251 Detour channel section 310 Pressure dissolution tank (pressure dissolution unit)
312 Water outflow pipe 319 Main tank

Claims (12)

A flow path forming member having a liquid inlet and a liquid outlet and having a flow path from the liquid inlet toward the liquid outlet formed therein;
Formed between the liquid inlet and the liquid outlet in a flow direction;
A throttle portion formed to have a smaller cross-sectional area and a higher flow velocity than both the liquid inlet and the liquid outlet;
A preparatory enlarged portion formed adjacent to the upstream side of the throttle portion, so that the cross-sectional area is larger than the throttle portion;
Connected to form a stepped surface in the circumferential direction with respect to the flow axis in a form adjacent to the upstream side of the preparatory enlarged portion, and has a smaller cross-sectional area than the preparatory enlarged portion at the connection side end with the preparatory enlarged portion. And a flow introduction portion formed to have a larger cross-sectional area than the throttle portion,
A micro-bubble characterized in that an outer peripheral region of the preparation expansion portion on the side connected to the flow introduction portion forms a flow buffer space that protects the periphery of the main flow that goes straight from the flow introduction portion into the preparation expansion portion. Generation mechanism. The preparatory enlarged portion is formed with a channel cross-sectional area smaller than the liquid inlet over the entire length in the flow direction,
The flow introduction part is formed between an inlet side introduction part connected to the preparation expansion part in a form following the liquid inlet, and the inlet side introduction part and the preparation expansion part.
The cross-sectional area is gradually reduced toward the preparatory enlarged portion so that the flow passage cross-sectional area is larger than the preparatory enlarged portion on the upstream end side and the flow passage cross-sectional area is smaller than the preparatory enlarged portion on the downstream end side. The microbubble generating mechanism according to claim 1, further comprising a preliminarily reduced diameter portion. A flow direction between the prepared reduced diameter portion and the prepared enlarged portion in the flow path so as to have a larger cross-sectional area than a minimum portion of the throttle portion and a smaller cross-sectional area than the inlet-side introduction portion. The microbubble generating mechanism according to claim 2, wherein a small diameter portion having a uniform cross-sectional area is formed. The microbubble generation according to claim 2 or 3, wherein a nozzle passage for sucking and introducing a gas into the liquid flowing through the throttle portion is formed in communication with the throttle portion due to the negative pressure generated in the throttle portion. mechanism. The microbubble generating mechanism according to claim 4, wherein the flow path is formed so that a cross-sectional area of the flow path is constant or monotonously increased in a section extending to the liquid outlet on the downstream side of the throttle portion. The flow introduction part is formed as an inlet side introduction part connected to the preparation expansion part in a form following the liquid inlet, and the preparation expansion part is larger than the liquid inlet on the connection side with the inlet side introduction part. A preliminarily reduced diameter portion that has a cross-sectional area and gradually decreases the cross-sectional area so that the flow-path cross-sectional area is smaller than the liquid inlet at the downstream end and larger than the throttle portion. The microbubble generation mechanism according to 1. A pressure dissolution unit that generates a pressurized concentrated gas solution in which the gas concentration is increased by forcibly dissolving the gas in the liquid by mixing the gas with the liquid and forcibly dissolving the gas;
A liquid outflow pipe for allowing the pressurized concentrated gas solution to flow out from the pressure dissolution unit while reducing the pressure, and
The microbubble generation mechanism according to claim 6, wherein the flow path forming member is provided on the liquid outflow pipe. A preparation diameter small portion having a uniform cross-sectional area is formed between the preliminarily reduced diameter portion and the constriction portion, which has a smaller channel cross-sectional area than the liquid inlet and larger than the constriction portion. The microbubble generation mechanism according to claim 6 or 7. The throttle part includes a collision member disposed in the flow path, and a throttle gap forming part facing the tip of the collision member in the flow path,
A bypass flow path is formed between the outer surface of the collision member and the inner surface of the flow path, and a lower flow rate and higher than the bypass flow path between the collision member and the throttle gap formation section. The microbubble generation mechanism according to any one of claims 1 to 8, wherein the microbubble generating mechanism has a structure in which a constriction gap is formed to allow the liquid flow to constrict while passing at a flow velocity. The micro bubble generating mechanism according to claim 9, wherein the bypass flow path portion is formed on both sides of the collision member in the flow direction when viewed from the water flow direction. 11. The microbubble generating mechanism according to claim 9, wherein a decompression cavity is formed in at least one of the opposing surfaces forming the aperture gap of the collision member and the aperture gap forming portion. The narrowing gap forming portion is formed as an opposing collision member that protrudes from the inner surface of the wall portion toward the collision member on the side opposite to the collision member with respect to the cross-sectional center of the flow path,
The microbubble generation mechanism according to any one of claims 9 to 11, wherein the throttle gap is formed between a protruding end portion of the collision member and a protruding end portion of the opposing collision member.