JP2011240209A - Mechanism for generating microbubble - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mechanism for generating microbubbles exhibiting a dramatically enhanced effect of micronizing bubbles, sufficiently achieving the micronization of bubbles even upon generating high-concentration bubbles by pressurizing/dissolving a gas.SOLUTION: A circumferential flow FS constituting a part of a flow of a bubble-containing liquid discharged from an accelerated flow guide 150 into an expanded section 151 becomes a swirl flow flowing across a reflection section 154 and the expanded section 151, whereby bubbles contained therein are vigorously stirred. In particular, coarse bubbles are readily incorporated into the circumferential flow FS forming the swirl flow, due to its tendency to be affected by buoyancy and centrifugal force, while micronized bubbles slightly affected by buoyancy and centrifugal force tend to be incorporated into a high speed central flow FM. As a result, coarser bubbles tend to stay longer in the swirl flow, and bubbles having been sufficiently micronized therein tend to be incorporated into the central flow FM, and hence the micronization of bubbles can sufficiently and uniformly be allowed to proceed.

Description

  The present invention relates to a microbubble generation mechanism.

  The microbubbles formed in the 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, in the conventional microbubble generation mechanism, as the flow element for further finely pulverizing the bubbles deposited in the water flow after passing through the throttle mechanism, the water flow itself that has passed through the throttle hole is associated with opening / turbulence. Only vortex generation can be expected, and there is a drawback that the level of bubble refinement is not sufficient. In addition, 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 likely to proceed.

  The object of the present invention is to provide a microbubble generation mechanism that can sufficiently achieve the miniaturization of bubbles even when the effect of micronization of bubbles is dramatically improved and gas is pressurized and dissolved to generate high-concentration bubbles. It is to provide.

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 hollow channel forming member having a liquid inlet and a liquid outlet and having a channel formed 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;
An accelerating flow guide portion that is formed subsequent to the throttle portion so that the cross-sectional area is smaller than the liquid outlet and discharges the flow accelerated at the throttle portion from the guide discharge port at the end;
An enlarged portion formed subsequent to the speed increasing flow guide portion so that the cross-sectional area is larger than the speed increasing flow guide portion;
The flow receiving port has a smaller cross-sectional area than the enlarged portion, and is enlarged so that the flow receiving port overlaps with the guide discharge port of the speed increasing flow guide portion by projection onto a plane orthogonal to the flow direction. A flow receiving portion that is formed linearly in a shape following the portion and is discharged from the guide discharge port of the speed increasing flow guide portion through the enlarged portion and is received at the flow receiving port and led to the liquid outlet; ,
The flow receiving portion is configured to communicate with the enlarged portion radially outside the flow receiving port while being substantially partitioned and separated from the flow receiving portion by the flow separation partition wall at the radially outer side with respect to the central axis of the flow receiving portion. The flow separation partition wall portion is formed so as to surround the downstream end and is separated from the flow receiving port by the flow separation partition portion. And a flow reflection portion that reflects the ambient flow component at the downstream end and returns it to the enlarged portion.

  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. In addition, the bubbles present in the liquid when supplied to the throttle unit are crushed into finer bubbles when passing through the throttle unit at high speed. As described above, in the conventional microbubble generation mechanism, the flow element for further finely pulverizing the bubbles precipitated in the water flow after passing through the throttle portion is not considered, and the growth of the precipitated bubbles and the originally coarse are not considered. Since the pulverization of the bubbles that existed in the state did not proceed sufficiently, microbubbles could not be generated efficiently.

  However, the microbubble generation mechanism of the present invention has succeeded in solving the above problems by forming a unique flow element having the following function of finely pulverizing bubbles. That is, an accelerating flow guide portion having a cross-sectional area smaller than that of the liquid outlet is formed following the throttle portion, and the water flow containing bubbles is maintained downstream from the squeezed portion while maintaining the state of speed increase. It is discharged to an enlarged part with a large road cross-sectional area. When the water flow straightened by the speed increasing flow guide portion is discharged from the guide discharge port to the enlarged portion, it tends to spread in the radially outward direction in the enlarged portion and the central flow component that tends to go straight by the inertial force. Divided into ambient flow components.

  And on the opposite side of the speed increasing flow guide part across the enlarged part in the flow direction, the flow receiving part opens in a positional relationship where the flow receiving inlet overlaps the guide discharge opening, and the central flow component is received by the flow receiving part. It flows from the entrance to the flow receiving part. On the other hand, the ambient flow component is separated from the central flow component by the flow separation partition that forms the peripheral edge of the flow receiving port and divides the flow receiving portion from the flow reflecting portion outside the flow receiving portion. It flows along the outer surface of the flow separation partition wall. Thereafter, the ambient flow component is reflected at the downstream end of the blocked flow reflecting portion and returned to the outer peripheral side of the enlarged portion. On the other hand, in the enlarged portion, the high-speed central flow ejected from the speed increasing flow guide portion has a lower pressure than the surroundings, so that the ambient flow component reflected and returned is re-entrained in the central flow near the guide discharge port.

  In this way, the liquid flow including bubbles released from the speed increasing flow guide part to the enlarged part becomes a swirl flow in which the surrounding flow component that forms part of the flow flows over the reflective part and the enlarged part, and the contained bubbles are vigorously stirred. To do. In particular, coarse bubbles are susceptible to the influence of buoyancy and centrifugal force, so they are easily incorporated into the surrounding flow components that form a swirl flow, while the high-speed central flow contains finer bubbles that are less affected by buoyancy and centrifugal force. There is a tendency to be easily taken in. As a result, the larger the bubble, the longer it stays in the swirl flow, and if it becomes sufficiently finer, it tends to be taken into the central flow, so that the bubble can be made sufficiently small and uniform.

  Hereinafter, various requirements that can be added to the present invention will be described. First, in the present invention, 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 and pressurizing the gas with the liquid, and the pressure dissolution A liquid outflow pipe for allowing the pressurized concentrated gas solution to flow out from the unit 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. Further, in the case of a pressurized concentrated gas solution, the concentration of dissolved liquid in the surroundings when the bubbles are deposited is high, so that it tends to grow rapidly. However, in the present invention, as described above, swirling flow is generated in the enlarged portion following the throttle portion, and a high-concentration bubble specific to pressure dissolution is generated by a unique mechanism that selectively takes in fined bubbles into the central flow. It can be uniformly miniaturized, and a large amount of microscopic and long-life bubbles can be generated extremely efficiently.

  The speed increasing flow guide portion is preferably formed as a uniform cross-sectional portion having a uniform cross-sectional area in the flow direction in order to make the central flow formation in the enlarged portion more remarkable. Further, in order to generate the central flow more remarkably, it is desirable to form the flow receiving port with a diameter larger than the guide discharge port (for example, 3 to 20% in diameter).

  Further, the guide discharge port of the speed increasing flow guide portion and the flow reception port of the flow receiving portion are preferably formed concentrically with respect to the central axis. As a result, the ambient flow component can be uniformly generated around the central axis, and as a result, the swirl flow for finely pulverizing the bubbles can be generated remarkably and evenly around the central axis. This effect becomes more remarkable when the enlarged portion, the guide discharge port, and the flow reflecting portion are formed concentrically with respect to the central axis.

  Next, a preliminary throttle mechanism that accelerates the water flow from the liquid inlet and guides it to the throttle gap can be provided between the liquid inlet and the throttle gap. By providing such a preparation throttle mechanism, the throttle gap and the flow velocity around it can be further increased, and the bubbles can be further miniaturized and concentrated. Specifically, the preliminary throttle mechanism is adjacent to the upstream side of the throttle part in the flow path, and has a smaller cross-sectional area than the enlarged part and a larger cross-sectional area than the minimum part of the throttle part. A preparatory diameter small portion having a uniform cross-sectional area in the direction, and a preliminarily reduced diameter portion adjacent to the upstream side of the preparatory diameter small portion and continuously reducing the channel cross-sectional area toward the inlet of the preparatory diameter small portion; Can be formed. 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 inner peripheral surface of the flow reflecting portion formed by the flow separation partition wall can be an inclined surface that increases in diameter toward the downstream side. In this way, the ambient flow component separated to the outside of the central flow by the flow separation partition is reflected while being guided radially outward along the inner peripheral surface of the flow reflecting portion forming the inclined surface, and the enlarged portion It is possible to smoothly return to the guide discharge port through the outer peripheral portion, and to generate a swirl flow for pulverizing coarse bubbles more efficiently.

  Further, in the flow path, the radial direction of the guide discharge port is substantially separated from the increased flow guide portion by the second flow separation partition portion on the radially outer side of the increased flow guide portion with respect to the central axis. Surrounding the speed increasing flow guide part in a form communicating with the enlarged part on the outside, the upstream end is formed to be closed, reflected by the flow reflecting part, and then returned to the outside of the guide discharge port through the enlarged part. A second flow reflecting portion may be formed that receives the flow along the outer surface of the second flow separation partition wall portion, reflects the flow at the upstream end, and returns the flow to the enlarged portion. In this way, the ambient flow component reflected by the flow reflecting portion and returning to the enlarged portion passes through the enlarged portion and enters the second flow reflecting portion, and is further reflected again along the outer surface of the second flow separating partition. , Can return smoothly to the guide discharge port. As a result, a swirl flow for pulverizing coarse bubbles can be generated more efficiently. In this case, if the inner peripheral surface of the second flow reflecting portion formed by the second flow separation partition is an inclined surface that is reduced in diameter toward the downstream side, this effect is further enhanced. In addition, it is desirable to form the second flow reflecting portion concentrically with respect to the central axis.

  In addition, when the second flow reflecting portion is formed on the flow path forming member together with the second flow separation partition portion, the first portion including the speed increasing flow guide portion and the first portion including the flow receiving portion are provided for the convenience of manufacturing the member. It can be divided into two parts.

  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 bypass flow path is formed between the outer surface of the collision member and the inner surface of the flow path, and the flow rate is lower and higher than the bypass flow path between the collision member and the throttle gap forming section. A squeezing gap that allows liquid to pass therethrough is formed. 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 bypass flow path portion for bypassing the flow is formed, the fluid resistance does not increase excessively when passing through the gap, and as a result, a liquid flow that is much faster than in the past 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. Separately from this, the liquid flow that has collided with the collision member and passed through the detour channel portion flows around the downstream side 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 above configuration, the accelerating flow guide portion can be formed as a uniform cross-sectional portion having a uniform cross-sectional area in the flow direction, and the uniform cross-sectional portion is extended to a predetermined length beyond the throttle portion on the upstream side in the flow direction. The above-mentioned preparation diameter small part can be formed. By making the cross section uniform before and after the throttle part, it is possible to further increase the speed of the flow passing through the throttle part. Further, if the preparation diameter small portion and the speed increasing flow guide portion are formed as cylindrical surfaces, there is an advantage that the preparation diameter small portion and the speed increasing flow guide portion can be formed in a lump by drill drilling or the like.

  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 gas in the liquid flow increases, and the concentration of microbubbles in the liquid flow 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.

  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.

  When the speed increasing flow guide portion and the preparation diameter small portion are formed by the inner peripheral surface of the cylindrical flow path wall portion, the collision member and the opposing collision member are the speed increasing flow guide portion and the preparation diameter reducing portion in the flow direction. Can be provided in such a manner as to project in the radial direction with respect to the central axis from the inner peripheral surface of the flow path wall.

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 expanded-axis sectional view of the aperture gap structure formed using a collision member. The figure explaining the three-dimensional structure of the downstream from the aperture | diaphragm | squeeze part of a bubble miniaturization nozzle. The axial direction projection figure which shows the formation relationship of a guide discharge port and a flow receiving port. 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. Action | operation explanatory drawing of a bubble miniaturization nozzle. The simulation image 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 pressure introduction conduit 311 extends from the discharge side of the pump 301, and its end is connected to a pressure dissolution tank 310 (pressure dissolution unit). 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. 2 is a plan view and a cross-sectional view showing a configuration example of the bubble miniaturization nozzle 21. 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. 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. . 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.
Speed increasing flow guide portion 150: formed following the throttle portion 21J so that the cross-sectional area is smaller than that of the liquid outlet 106, and the flow increased at the throttle portion 21J is discharged from the guide discharge port 150p at the end. . In this embodiment, the accelerating flow guide 150 is formed as a uniform cross-section having a uniform cross-sectional area in the flow direction, specifically, a cylindrical surface.
Enlarged portion 151: formed following the accelerating flow guide portion 150 so that the cross-sectional area is larger than that of the accelerating flow guide portion 150. In this embodiment, the enlarged portion 151 is formed as a cylindrical surface that is flush with the inner peripheral surfaces of the reflecting portion 154 and the second reflecting portion 156 described later.

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 is a guide for the accelerating flow guide unit 150 by projection onto a plane orthogonal to the flow direction. It is linearly formed following the enlarged portion 151 so as to overlap the discharge port 150p. The central flow FM (FIG. 14) component discharged from the guide discharge port 150p of the accelerating flow guide portion 150 through 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 formed in a cylindrical surface shape having a larger diameter than the speed increasing flow guide portion 150.

Flow reflecting portion 154: The flow receiving partition 152 is substantially partitioned and separated from the flow receiving portion 152 by the flow separation partition 153 on the radially outer side with respect to the central axis of the flow receiving portion 152, and the enlarged portion is radially outside the flow receiving inlet 152p. 151 is formed so as to surround the flow receiving portion 152 so as to communicate with 151 and to close the downstream end. The flow separation partition 153, while the peripheral flow FS (FIG. 14) spreading outward in the radial direction of the central flow FM (FIG. 14) component in the enlarged portion 151 is separated to the outside of the flow receiving port 152 p by the flow separation partition 153. And the ambient flow FS is reflected at the downstream end and returned to the enlarged portion 151. The inner peripheral surface of the flow reflecting portion 154 formed by the flow separation partition wall portion 153 is an inclined surface that increases in diameter toward the downstream side, in this embodiment, a conical surface.

Second flow reflection portion 156: The guide flow is released while being substantially separated from the acceleration flow guide portion 150 by the second flow separation partition portion 155 on the radially outer side of the acceleration flow guide portion 150 with respect to the central axis O. The speed increasing flow guide portion 150 is surrounded in a form communicating with the enlarged portion 151 on the radially outer side of the outlet 150p, and the upstream end is closed. After being reflected by the flow reflecting portion 154, the flow returning to the outside of the guide discharge port 150p through the enlarged portion 151 is received along the outer surface of the second flow separating partition 155, and the flow is reflected at the upstream end. To return to the enlargement unit 151. The inner peripheral surface of the second flow reflecting portion 156 formed by the second flow separation partition wall portion 155 is an inclined surface that decreases in diameter toward the downstream side, in this embodiment, a conical surface.

  FIG. 4 schematically shows the three-dimensional shape of the main part of the mechanism formed on the downstream side of the throttle part. The guide discharge port 150p of the speed increasing flow guide portion 150 and the flow receiving port 152p of the flow receiving portion 152 are formed concentrically with respect to the central axis O. In the present embodiment, the enlarged portion 151, the guide discharge port 150p, the flow reflecting portion 154, and the second flow reflecting portion 156 are further formed concentrically with respect to the central axis O line. Further, as shown in FIG. 5, the flow receiving port 152p is formed larger in diameter (about 10%) than the guide discharge port 150p. As shown in FIG. 2, the flow path forming member 20 is divided into a first portion 25 </ b> A including the speed increasing flow guide portion 150 and a second portion 25 </ b> B including the flow receiving portion 152. The symbol PL is a divided surface that divides the first portion 25A and the second portion 25B, and the first portion 25A and the second portion 25B are in a known coupling form such as adhesion, press-fitting, and screwing. Integrated.

  Next, in the flow path FP, the cross-sectional area is uniform in the flow direction so as to be adjacent to the upstream side of the throttle portion 21J and to have a smaller cross-sectional area than the enlarged portion 151 and a larger cross-sectional area than the throttle portion 21J. A preparation diameter small portion 157 (in this embodiment, a cylindrical surface shape) is formed. Further, adjacent to the upstream side of the prepared small diameter portion 157, a prepared reduced diameter portion 30 that continuously reduces the channel cross-sectional area toward the inlet of the prepared small diameter portion 157 is formed. In the present embodiment, the prepared reduced diameter portion 30 is formed in a conical surface shape.

  Next, the structure of the aperture 21J will be described. As shown in FIG. 3, the throttle portion 21J includes a throttle gap 21G and a bypass flow path portion 251. 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.

  Returning to FIG. 2, the flow path forming member 20 is made of metal, ceramic or resin. As shown in FIGS. 2 and 3, the narrowing gap forming portion 23 is an opposing collision member (hereinafter referred to as “projecting”) 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 sectional center O of the flow path FP. The constriction gap 21G is formed between the front end of the collision member 22 in the protruding direction and the front end of the opposing collision member 23 in the protruding direction. As shown in FIG. 2, a connection external 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.

  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.

Next, FIG. 6 is a cross-sectional view showing the internal structure of the gas suction nozzle 315 (the same reference numerals are given to components that are conceptually common to the bubble miniaturization nozzle 21). 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 1156: 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.
The flow introducing portion 1150 is connected in a form adjacent to the upstream side of the preparation expanding portion 1156 so as to form a stepped surface in the circumferential direction with respect to the central axis O, and at the connection side end with the preparation expanding portion 1156 The cross-sectional area is smaller than that of the preparatory enlarged portion 1156, and the cross-sectional area is larger than that of the throttle portion 21J.
The outer peripheral region of the preparation expansion unit 1156 on the connection side with the flow introduction unit 1150 forms a flow buffer space 1155 that protects the periphery of the main flow that goes straight from the flow introduction unit 1150 into the preparation expansion unit 1156.

The preparation enlarged portion 1156 (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 introducing portion 1150 is formed between the inlet side introducing portion 25L connected to the preparation expanding portion 1156 in a form following the liquid inlet 31, and between the inlet side introducing portion 25L and the preparation expanding portion 1156, and is located on the upstream end side. The preparation enlargement section 1156 has a flow passage cross-sectional area larger than the preparation enlargement section 1156 at (inner diameter d ₁ ) and smaller than the preparation enlargement section 1156 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 diameter-reduced portion 30 and the prepared enlarged portion 1156 is cut in the flow direction so as to have a larger cross-sectional area than the minimum portion of the throttle 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 a flow introducing portion 1150 together with the prepared reduced diameter portion 30 and has a cross-sectional area equal to the outlet side opening of the prepared reduced diameter portion 30 and is formed in a cylindrical surface here. 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 1156 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 is the bubble miniaturization described with reference to FIG. 3 in that the restricting gap 21G and the bypass flow passage portion 251 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 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. (FIG. 3) is formed with a gas outlet 226d opened in the inside, and the other end penetrating the flow passage wall 25 and opening the gas intake 226e on the outer surface of the wall (the aforementioned tool engagement hole). 222 and the vacuum cavity 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 through the nozzle passage 226 due to the negative flow pressure generated in the throttle gap 21G (FIG. 3). The gas is taken in and ejected from the gas ejection port 226d into the narrowing gap 21G.

  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. 6, 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 raw water passes through the preparation diameter reduced portion 157 and the preparation enlarged portion 1156. It is supplied to the diaphragm unit 21J.

  The preparation diameter small portion 157 and the preparation expansion portion 1156 that form the end of the flow introduction portion 1150 discontinuously increase the cross-sectional area by forming a stepped surface at the connection position between them. Since the cross-sectional area of the flow path is discontinuously enlarged as described above, a stagnation region having a low flow velocity is formed as a flow buffer space 1155 around the connection opening of the preparation diameter small portion 157 at the upstream end portion of the preparation expansion portion 1156. It is formed. An outer peripheral portion of the main flow FD that goes straight from the preparation diameter small portion 157 into the preparation expansion portion 1156 spreads in the flow buffer space 1155 and swirls in the direction opposite to the main flow FD to generate a vortex flow SW. That is, in the flow buffer space 1155, the vortex SW is generated so as to surround the periphery of the main flow FD, so that the pressure loss of the main flow FD due to friction with the flow path FP wall surface is reduced.

  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 1156 having a smaller channel cross-sectional area than the liquid inlet 31, but the high-speed liquid flow is preparatory enlargement. Loss is reduced by the vortex SW formed in the flow buffer space 1155 of the portion 1156, 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.

  Then, the pressurized concentrated gas solution flowing out from the pressurized dissolution tank 310 to the water outflow pipe 312 through the pressure valve 316 flows into the bubble miniaturization nozzle 21 of FIG. In the bubble miniaturization nozzle 21, when pressurized concentrated gas-dissolved water is supplied from the liquid inlet 31 to the flow path FP, a negative water flow pressure is generated in the throttle gap 21G, as shown in FIGS. Then, the dissolved gas is precipitated by the cavitation effect, and bubbles BM are generated 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. 7, 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 gas precipitation bubbles BM formed in the gap-passing water flow WF are entrained in the wraparound turbulent flow CF and crushed into microbubbles 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. 9A, 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. 2). 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 21 </ b> G form a detour channel portion 251 that detours the water flow that collides with the channel wall portion. . 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 222 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 222 is brought into a negative pressure state of 0.02 MPa or more. Can be easily maintained. In addition, since the entire region in the decompression cavity 222 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 the 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 in the throttle gap 21G, the decompression cavity 222, or the downstream side 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. 7, 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. 9C, the flow through the constricted gap 21G including the precipitated bubbles BM is subjected to agitation by a number of vortexes while continuing bubble precipitation in the negative pressure region on the downstream side of the gap. . As shown in FIG. 3, the peripheral region of the narrowing gap 21G has an annular gap peripheral space 251n having a wedge-shaped cross section and the space outer peripheral side opening to the detour channel portion 251. Portions located on both sides of the narrowing gap 21G in the water flow direction on the outer peripheral surface of the portion 23k also function as auxiliary gaps. Therefore, as shown in FIG. 11 (the JJ cross section in FIG. 7), cavitation occurs also in the water flow passing through the auxiliary gap, and the generated bubble BM is entangled in the vortex SWE on the outlet side and crushed. 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 turbulent flow, as described above, a large number of fine eddy currents SWE are densely formed in a three-dimensional manner, and as shown in the upper part of FIG. 8, 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. 8, 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. 12, 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 cylindrical surface that is smooth. 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. 13, it is also possible to form a water flow peeling uneven | corrugated | grooved part as a serration part 22SR 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 becomes a high negative pressure region, and bubble precipitation due to 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. 9, the diameter of the tip of the opposing collision member 23 facing the decompression cavity 221 is reduced, so that 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, the bubble miniaturization nozzle 21 contains relatively coarse bubbles that are deposited and excessively grown after passing through the throttle portion 21J, or that are not sufficiently miniaturized even after passing through the throttle portion 21J. There is a case. In particular, when the pressurized concentrated gas solution dissolves gas up to the supersaturated region at normal pressure, there is a relatively high possibility that coarse bubbles remain even after passing through the throttle gap 21G. In the bubble miniaturization nozzle 21 that employs the microbubble generation mechanism of the present invention, such residual coarse bubbles are effectively finely pulverized by a specific flow element provided on the downstream side of the throttle portion 21J.

  FIG. 14 schematically shows the operation. That is, as shown in the upper part of FIG. 14, the speed increasing flow guide portion 150 having a cross-sectional area smaller than that of the liquid outlet 106 is formed following the throttle portion 21J, so that the water flow containing bubbles increases at the throttle portion 21J. While maintaining the speeded state, it is discharged to the enlarged portion 151 having a large flow path cross-sectional area formed downstream thereof. The water flow linearized by the accelerating flow guide section 150 is a radial direction within the expansion section 151 and the central flow FM component that is going to go straight by inertia when it is discharged from the guide discharge port 150p to the expansion section 151. It is divided into an ambient flow FS that tries to spread outward.

  And on the opposite side of the accelerating flow guide portion 150 across the enlarged portion 151 in the flow direction, the flow receiving portion 152 opens in a positional relationship where the flow receiving port 152p overlaps the guide discharge port 150p, The flow FM component flows into the flow receiving unit 152 from the flow receiving port 152p. On the other hand, the ambient flow FS is separated from the central flow FM component by the flow separation partition wall 153 that forms the peripheral edge of the flow receiving port 152p and partitions the flow receiving portion 152 from the flow reflecting portion 154 outside the flow receiving port 152p. Flows along the outer surface of the flow separating partition 153 into the flow reflecting portion 154 communicating with the flow.

  Thereafter, as shown in the center of FIG. 14, the ambient flow FS returning to the enlarged portion 151 passes through the enlarged portion 151 and enters the second flow reflecting portion 156, and is reflected once again to be reflected to the second flow separation partition wall portion 155. The guide discharge port 150p can be smoothly returned to along the outer surface. The ambient flow FS is reflected at the downstream end of the blocked flow reflecting portion 154 and returned to the outer peripheral side of the enlarged portion 151. In the enlarged portion 151, the high-speed central flow FM ejected from the accelerating flow guide portion 150 has a lower pressure than the surroundings, so that the ambient flow FS that is reflected back returns to the central flow FM near the guide discharge port 150p. Get involved in.

  As shown in the lower part of FIG. 14, in the flow of liquid containing bubbles released from the accelerating flow guide unit 150 to the expansion unit 151, the ambient flow FS that forms a part of the flow flows, and the reflection unit 154, the expansion unit 151, A swirling flow that spans the bubbles and vigorously stirs the contained bubbles. In particular, coarse bubbles are susceptible to the influence of buoyancy and centrifugal force, and therefore are easily incorporated into the surrounding flow FS that forms a swirling flow. On the other hand, the high-speed central flow FM has finer bubbles that are less affected by buoyancy and centrifugal force. Tend to be captured. As a result, coarser bubbles stay longer in the swirling flow and tend to be taken into the central flow FM if the micronization is sufficiently advanced. Therefore, the micronization of the bubbles can be sufficiently and uniformly advanced.

  The flow receiving port 152p is formed slightly larger in diameter than the guide discharge port 150p, and the ratio of the ambient flow FS that remains as a swirling flow in the enlarged portion 151 is appropriately adjusted. Moreover, as shown in FIG. 4, each inner peripheral surface of the flow reflection part 154 and the second flow reflection part 156 formed by the flow separation partition part 153 and the second flow separation partition part 155 approaches the end of each reflection part. The inclined surface becomes larger in diameter, and the formation of a swirling flow over the reflecting portions 154 and 156 and the enlarged portion 151 is promoted, and the effect of crushing coarse bubbles is further enhanced.

  FIG. 15 shows simulation results obtained by analyzing the flow in the flow path of the bubble miniaturized nozzle 21 having the shape shown in FIG. 2 using commercially available thermal fluid analysis software (EFD.Lab, manufactured by Structural Planning Laboratory Co., Ltd.). It 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. It can be seen that a high-speed central flow FM and an ambient flow FS that forms a swirl flow across the flow reflecting portion 154, the expanding portion 151, and the second flow reflecting portion 156 are remarkably formed in the expanding portion 151. The swirl flow also includes a flow component along the circumferential direction of the outer circumferential surface of the conical surface of the flow separation partition wall portion 153 and the second flow separation partition wall portion 155, and is evenly distributed around the central axis of the enlarged portion 151. You can see that Furthermore, it can be seen that the swirling flow is drawn in concentratedly slightly downstream of the guide discharge port 150p. It was also confirmed that the flow velocity in the restricting portion 21J and the restricting gap 21G exceeded 25 m / sec.

  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. 16 is substantially the same as the configuration of FIG. 2, but the cross-sectional shapes of the downstream end surface 153r of the reflecting portion 154 and the upstream end surface 155r of the second reflecting portion 156 are curved ( That is, it is formed in a rounded surface shape. The cross-sectional shapes of the outer peripheral surfaces 153p 'and 155p' of the flow separation partition 153 and the second flow separation partition 155 are also curved in a concave 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. 17 shows a configuration in which the second flow separation partition and the second reflecting part are omitted. The total length of the accelerating flow guide portion 150 is shortened by the amount that the second flow separation partition wall is omitted. The upstream end face of the reflecting portion 154 has a cut-off surface shape, and the reflection form on the upstream side may be slightly disturbed, but the formation of the swirling flow itself is still remarkable by the reflecting portion 154 on the downstream side, and bubbles are finely pulverized. The effect can be fully expected.

  Hereinafter, various modifications for forming the aperture gap will be described. FIG. 18 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. 19 shows an example in which the opening inner peripheral surface of the decompression cavity 221 is a counterbore taper surface 1224 corresponding to the tapered peripheral side surface 231 at the tip of the opposing collision member 23. By forming the taper surface 1224, the effect of guiding the water flow to the front end side of the opposing collision member 23 is enhanced.

  FIG. 20 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. 21 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. 22 shows an example in which the collision member 22 and the opposing collision member 23 are integrally coupled in the axial direction by the constriction connecting portion 21C, and the constriction gap 21G 'is formed through the constriction coupling portion.

  In FIG. 23, 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.

  Further, FIG. 24 shows 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 wall portion 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. 25 shows an example in which the opposing collision member 123 is formed wider than the collision member 22 so that the detour channel portion 251 does not occur on the side of the opposing collision member 123.

  FIG. 26 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 (throttle gap forming part)
23k diameter-reduced part 30 preparation diameter-reduced part FP flow path 31 liquid inlet 106 liquid outlet 150 speed increasing flow guide part 150p guide discharge port 151 enlarged part 152p flow receiving inlet 152 flow receiving part FM central flow FS ambient flow 153 flow separation partition part 154 Flow reflection part 155 Second flow separation partition part 156 Second flow reflection part 157 Preparation diameter small part 221 Depressurization cavity 226 Nozzle passage 231 Tapered peripheral side surface (throttle inclined surface, enlarged inclined surface)
241 Nozzle passage 251 Detour channel section 310 Pressure dissolution tank (pressure dissolution unit)
312 Water outflow pipe 319 Main tank

Claims (12)

A hollow 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;
An accelerating flow guide portion that is formed subsequent to the throttle portion so as to have a smaller cross-sectional area than the liquid outlet, and discharges the flow accelerated at the throttle portion from a guide discharge port at the end;
An enlarged portion formed subsequent to the speed increasing flow guide portion so that a cross-sectional area is larger than the speed increasing flow guide portion;
The flow receiving port has a smaller cross-sectional area than the enlarged portion, and the flow receiving port overlaps with the guide discharge port of the speed increasing flow guide portion by projection onto a plane orthogonal to the flow direction. Is formed linearly in a form following the enlarged portion,
A flow receiving portion for receiving a central flow component discharged from the guide discharge port of the speed increasing flow guide portion through the enlarged portion and guiding the component to the liquid outlet;
The flow is communicated with the enlarged portion radially outside the flow receiving port while being substantially separated from the flow receiving portion by the flow separation partition wall at a radially outer side with respect to the central axis of the flow receiving portion. It surrounds the receiving part and is formed so that the downstream end is closed.
The peripheral flow component spreading radially outward of the central flow component in the enlarged portion is received along the outer surface of the flow separation partition while being separated to the outside of the flow receiving port by the flow separation partition. A microbubble generating mechanism, comprising: a flow reflecting portion that reflects a surrounding flow component at a downstream end and returns the reflected component to the enlarged portion. 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;
2. A microbubble according to claim 1, wherein a liquid outflow pipe for allowing the pressurized concentrated gas solution to flow out from the pressure dissolution unit while reducing pressure is provided, and the flow path forming member is provided on the liquid outflow pipe. Generation mechanism. The microbubble generation mechanism according to claim 1 or 2, wherein the guide discharge port of the speed increasing flow guide portion and the flow reception port of the flow receiving portion are formed concentrically with respect to the central axis. The microbubble generating mechanism according to claim 3, wherein the flow receiving port is formed larger in diameter than the guide discharge port. The microbubble generation according to any one of claims 1 to 4, wherein an inner peripheral surface of the flow reflecting portion formed by the flow separation partition wall is an inclined surface that increases in diameter toward the downstream side. mechanism. With respect to the central axis, on the radially outer side of the accelerating flow guide portion, the second flow separation partition portion substantially separates the accelerating flow guide portion from the accelerating flow guide portion, and the enlarged portion on the radially outer side of the guide discharge port. It is formed in such a way that it surrounds the speed-increasing flow guide part in a communicating form and the upstream end is closed.
After being reflected by the flow reflecting portion, the flow returning to the outside of the guide discharge port through the enlarged portion is received along the outer surface of the second flow separation partition wall, and the flow is reflected at the upstream end. 6. The microbubble generating mechanism according to claim 1, further comprising a second flow reflecting portion that returns to the enlarged portion. The microbubble generating mechanism according to claim 6, wherein an inner peripheral surface of the second flow reflecting portion formed by the second flow separation partition is an inclined surface having a diameter reduced toward the downstream side. The throttle portion includes a collision member disposed in the flow path,
A throttle gap forming portion 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 generating mechanism according to any one of claims 1 to 7, wherein the microbubble generating mechanism has a structure in which a constriction gap is formed to allow the liquid flow to pass while constricting so as to have a flow velocity. The speed increasing flow guide portion is formed as a uniform cross-sectional portion having a uniform cross-sectional area in the flow direction, and the uniform cross-sectional portion is extended to the upstream side in the flow direction by a predetermined length beyond the throttle portion. The microbubble generation mechanism according to claim 8, wherein a small portion is formed. 10. The microbubble generating mechanism according to claim 8, 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 in the flow path. 11. The microbubble generating mechanism according to claim 8, wherein a decompression cavity is formed on 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 flow path 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 narrowing gap is formed as the collision member The microbubble generating mechanism according to any one of claims 8 to 11, wherein the microbubble generating mechanism is formed between a forward end portion of the opposite impact member and a forward end portion of the opposing collision member.