JP5170409B2 - Swirl type microbubble generator - Google Patents

Description

  The present invention relates to a swirling flow type microbubble generator and a pressure blocking nozzle, and is suitable for application to various processes using microbubbles.

  Microbubbles are fine bubbles having a bubble diameter of generally 10 to several tens of μm at the time of generation, and are extremely small compared to bubbles having a diameter of several millimeters that are normally generated in water. Since microbubbles are extremely small in this way, they have the property of adsorbing fine dust and floating on the surface of the water, and are applied to marine product cleaning and water purification.

  Conventionally, swirl type microbubble generators are often used as the microbubble generators. However, this swirl type microbubble generator 1) noise associated with the generation of sound waves, 2) re-inhalation of the released fluid when released in water, and 3) re-foaming of dissolved gas by generation of a low-pressure part at the center of the swirl flow There are many issues such as. The generation of sound waves of 1) causes noise problems when the swirl type microbubble generator is used for consumer goods or water quality improvement. Here, it is known that the sound wave emitted from the swirling flow type microbubble generator has vibrations of two kinds of frequencies, that is, the swirling frequency and the natural frequency of the air column formed inside the device. In 2), the floc is broken and dispersed in the liquid by re-inhaling the released fluid when the floc is floated and separated by microbubbles. 3) prevents the solubility of dissolved gas from increasing.

  2. Description of the Related Art Conventionally, a swirling fine bubble generating device is known in which a baffle plate (baffle plate) is installed at a swirling gas-liquid outlet of a conical space for swirling flow generation (see Patent Document 1). According to this, generation and diffusion of fine bubbles can be promoted.

  Further, a fine bubble generator in which a cap having a raised portion is installed at a nozzle outlet of a swirling flow and a fine bubble generator provided with the same are known (see Patent Document 2). According to this, it is said that the inside of the mixed fluid can be depressurized, fine bubbles can be efficiently generated, and the ejection amount and the number of swirling can be increased. Patent Document 2 also describes that the distance between the cap portion and the nozzle depends on the ejection hole, the volume of gas, the discharge pressure of the pump, and the like.

Further, as a bubble generating means for applying a shearing force to the swirling flow by using swirling flow, a bubble generating device is known in which a lattice is installed in the downstream portion at the nozzle outlet of the swirling flow (see Patent Document 3). ). According to this, it is described that a large shear can be applied to the swirling flow.
In addition, the swirl | vortex type | mold microbubble generator using a vortex collapse phenomenon is proposed (for example, refer patent document 4).

JP 2003-205228 A International Publication No. 01/097958 Pamphlet JP 2005-169286 A International Publication No. 06/075452 Pamphlet

However, according to the study of the present inventors, the techniques described in Patent Documents 1 to 3 cannot solve the above problems 1) to 3).
Therefore, the problems to be solved by the present invention are to effectively prevent noise accompanying the generation of sound waves, re-inhalation of the released fluid at the time of underwater discharge, re-foaming of dissolved gas due to generation of a low-pressure part at the center of the swirling flow, etc. The present invention provides a swirling flow type microbubble generator capable of performing the above and a pressure blocking nozzle suitable for use in the device.

In order to solve the above problem, the first invention is:
A second nozzle for pressure blocking provided on the end face on the downstream side of the first nozzle having a micro-bubble jet port, which is opposed to the first nozzle and provided coaxially;
A gap is formed between the downstream end surface of the first nozzle and the upstream end surface of the second nozzle,
The gap interval increases radially from the central axis of the first nozzle and the second nozzle,
The portion of the second nozzle that faces the jet outlet is configured to block the low-pressure portion at the center of the swirling flow coming out of the jet outlet from the downstream side of the second nozzle,
The swirling flow type microbubble generator is characterized in that a portion of the second nozzle facing the jet port does not penetrate the jet port.

In this swirling flow type microbubble generator, the microbubbles ejected from the outlet of the first nozzle are the gap between the downstream end surface of the first nozzle and the upstream end surface of the second nozzle. It is configured to go to the outside through. From the viewpoint of minimizing the pressure in the air column, in other words, maximizing the suction pressure, the apex angle of the downstream end face of the first nozzle is θ _VB , and the apex angle of the upstream end face of the second nozzle is θ _{When SU} is set, θ _SU ≦ θ _VB is preferable, and Δθ≡θ _VB −θ _SU = 0 to 20 ° is more preferable. In addition to this, from the viewpoint of minimizing the pressure in the air column, in other words, maximizing the suction pressure, the diameter of the jet outlet at the downstream end face of the first nozzle is set to _De , the first nozzle, and the second nozzle. when the distance between the first nozzle and the second nozzle on the central axis of the nozzle was t, it is preferable that t is approximately D _e / 4. The jet nozzle of the first nozzle is typically cylindrical, and in this case, the diameter _De is constant over the entire length of the cylindrical jet, but is not limited to this. Te, in the length direction of the jetting port may be changed diameter D _e.

  Typically, the first nozzle and the second nozzle are typically accommodated in a cylindrical tube (pipe), and the microbubbles ejected from the ejection nozzle of the first nozzle So as to be discharged to the outside through a space between the pipe and a plurality of grooves provided on the outer peripheral surface of the second nozzle in parallel with the central axis of the second nozzle. Composed. Alternatively, instead of forming a groove on the outer peripheral surface of the second nozzle, a portion of the second nozzle adjacent to the outer peripheral surface of the second nozzle is parallel to the central axis of the second nozzle. A plurality of holes may be provided. Alternatively, the first nozzle and the second nozzle are housed inside the tube, the second nozzle has a shape that is recessed downstream, and the second nozzle has the above-mentioned shape inside. There are provided a plurality of holes that communicate between the gap in the portion adjacent to the inner wall of the tube and the downstream end surface of the second nozzle and that merge with each other at the downstream end surface of the second nozzle. The microbubbles ejected from the ejection port pass through the gap, and are discharged to the outside through the plurality of holes of the second nozzle. The aspect ratio (length / inner diameter) of these grooves or holes is preferably greater than 1.

Typically, the first nozzle is a vortex breakdown nozzle having a contracted flow portion and a vortex breakdown portion sequentially from the upstream side toward the downstream side. Here, vortex breakdown is a phenomenon in which the structure of the vortex changes abruptly. There are two types: spiral type (type generated in the case of a delta wing) and bubble type (type generated in the case of flow in a circular pipe). Has two distinct types. Further, typically, an airfoil third nozzle for generating a swirling flow is provided on the upstream side of the first nozzle. In this case, typically, a swirl flow is generated by supplying a liquid to the upstream inlet of the third nozzle, a gas is introduced into the center of the swirl flow, and the gas is introduced into the center. By supplying the swirling flow to the contracted part of the first nozzle, microbubbles are generated from the vortex breaking part. The third nozzle typically has a swirl flow generating wing body accommodated in a cylindrical pipe (pipe) (or a swirl flow generation wing body covered with a pipe). It is. The swirling flow generating wing is typically streamlined at one end of a cylindrical main body (typically, a rotating body having a central axis of the main body as a rotation axis (eg, hemispherical)). A plurality of blades are formed in the longitudinal direction of the outer peripheral surface of the main body so that their rear portions are bent, and a gas injection hole is provided at the other end of the main body. The swirl flow generating wing body typically has an air supply hole provided in the outer peripheral surface of the main body and an injection hole provided in the other end of the main body, and the swirl flow generating blade. The number of body wings can be selected as needed. In the vortex breakdown nozzle, typically, the cross-sectional area of the contracted flow portion gradually decreases toward the vortex collapse portion (or the contracted flow portion is narrowed toward the vortex collapse portion). The cross-sectional shape is the same as that of the vortex breakdown part at the boundary (or connection part) with the vortex breakdown part. Preferably, the vortex collapse portion includes a first portion having a cylindrical shape and a second portion having a shape extending toward the outlet, and an inner peripheral surface of the first portion and an end surface of the second portion. when is the angle formed was theta _0, 0 degree <θ ₀ <180 deg or 90 deg <θ ₀ <180 °, for example, about 100 degrees. When the vortex breaking part has a first part having a cylindrical shape and a second part having a shape spreading toward the outlet, the inner peripheral surface of the first part and the end face of the second part are smoothly connected. It is desirable that By carrying out like this, a swirl flow can be made to adhere to the end surface of the 2nd part which is the ejection surface of the vortex collapse nozzle.

The liquid that generates the microbubbles may be basically any type, specifically, for example, water (including hot water), various organic solvents (alcohol, acetone, toluene, etc.), Liquid fuels such as oil and gasoline.
The gas supplied to the center of the swirling flow may be basically any one, but specifically, for example, air, oxygen, ozone, hydrogen, argon, or the like.

The second invention is
A pressure blocking nozzle that faces the nozzle on the downstream end face side of the nozzle having the microbubble jet of the swirling flow type microbubble generator and is provided coaxially,
A gap is formed between the downstream end surface of the nozzle having the jet port and the upstream end surface of the pressure blocking nozzle,
The gap interval increases in a radial direction from the central axis of the nozzle having the nozzle and the pressure blocking nozzle,
The portion of the pressure blocking nozzle that faces the jet port is configured to block the low pressure portion at the center of the swirling flow coming out of the jet port from the downstream side of the second nozzle,
A portion of the pressure blocking nozzle that faces the jet port is configured not to penetrate the jet port.

In the second invention, the nozzle having the microbubble jet nozzle and the pressure blocking nozzle correspond to the first nozzle and the second nozzle in the first invention, respectively.
In the second invention, what has been described in relation to the first invention is established.

  According to the present invention, it is possible to effectively prevent noise accompanying the generation of sound waves, re-inhalation of the released fluid when released in water, and re-foaming of dissolved gas due to generation of a low-pressure part at the center of the swirling flow.

Hereinafter, a swirling flow type microbubble generator according to an embodiment of the present invention will be described with reference to the drawings.
First, a swirl type microbubble generator that is the basis of a swirl type micro bubble generator according to this embodiment will be described (see Patent Document 4).
In the swirl type microbubble generator according to the first example, in order to generate microbubbles, a strong swirl from a liquid such as water flowing in the pipe by closing the center of the pipe and increasing the flow velocity in the circumferential direction. A turbine blade-type nozzle that generates a flow and a vortex breakdown nozzle that transitions a flow that is superior in circulation compared to the main flow to a smaller flow are arranged in series.

  1 shows a main body of a swirling flow type microbubble generator 1 according to the first example, FIGS. 2 to 4 show blade bodies of a turbine blade type nozzle of the swirling flow type microbubble generator 1, and FIG. 5 shows this turbine blade type. FIG. 6 is a development view of one wing of the wing body of the nozzle, FIG. 6 shows a vortex breaking nozzle of the microbubble generator 1, and FIG. 7 shows an air supply device of the swirl type microbubble generator 1.

  As shown in FIGS. 1 to 7, the swirl type microbubble generator 1 accommodates a turbine blade type nozzle 3 and a vortex breaking nozzle 4 which are coaxially coupled in series with each other inside a cylindrical pipe 2. And the air supply device 5. The turbine blade type nozzle 3 is formed by forming a front a of a cylindrical main body 3a into a hemispherical shape, and providing a plurality of blades 3b in the longitudinal direction of the outer peripheral surface b of the main body 3a so that their rear c bends. The outer side of the wing body provided with the injection hole 3f in d is covered with a pipe 2 in a tubular shape. The vortex breaking nozzle 4 is disposed at the tip end e of the pipe 2. The vortex breaking nozzle 4 is formed by connecting a tubular vortex breaking portion 4b to a contracted flow portion 4a formed into a tapered shape. The air supply device 5 detects the pressure difference of the vortex breakdown portion 4b of the vortex breakdown nozzle 4 and adjusts the amount of gas 5l (see FIG. 7) supplied to the turbine blade nozzle 3. In the pipe 2, the liquid 6 flows in the order of the inlet 2 a, the turbine blade nozzle 3, the vortex section 2 b, and the vortex breakdown nozzle 4. The pipe 2 can accommodate various sizes so that it can be connected to existing equipment.

In this swirling flow type microbubble generator 1, a liquid 6 such as water for generating microbubbles is caused to flow into an inlet 2 a of a pipe 2, and a liquid flow 6 a such as a water flow is caused to flow in a circumferential direction by a turbine blade type nozzle 3. The air column 6b is ejected while being directed to f, and the vortex collapse nozzle 4 is used to contract the vortex to cause the vortex to collapse. More specifically, the liquid 6 entering from the inlet 2a of the pipe 2 becomes a liquid flow 6a having an increased flow velocity because the central portion is closed by the turbine blade nozzle 3. The liquid flow 6a flows along the groove 3d existing on the outer peripheral surface b of the turbine blade type nozzle 3, and when the direction is changed in the circumferential direction f of the turbine blade type nozzle 3, the swirl flow 6c becomes the swirl portion 2b. Continue on. In the vortex section 2b, the air column 6b discharged from the injection hole 3f of the turbine blade type nozzle 3 flows spirally together with the swirl flow 6c. When entering the vortex breaking nozzle 4, the swirling flow 6 c is contracted, and vortex collapse occurs due to the superior flow compared to circulation. Due to this vortex breakdown, large bubbles are finely crushed and become microbubbles 6d which are discharged from the outlet of the vortex breakdown nozzle 4. Here, if the rotation frequency _fe of the swirling flow 6c in the minimum cross section of the vortex breaking nozzle 4, that is, the cross section of the vortex breaking portion 4b, is preserved in the contracted flow portion 4a, the swirling flow 6c in the swirl flow portion 2b. the rotational frequency f, when the inner diameter D of the pipe 2, the inner diameter of the vortex breakdown section 4b was D _e, a _{f e = (D / D e} ) 2 f.

The turbine blade-type nozzle 3 is an instrument that converts a liquid flow 6a such as a water flow into a spiral swirl flow 6c and discharges an air column 6b. A plurality of turbine blade-type nozzles 3 are disposed on the outer peripheral surface b of the main body 3a. The wing body provided with the wing 3b is fixed. The turbine blade nozzle 3 does not need to be rotated and does not require power. The air column 6b is a bubble in which a gas 51 such as air is vigorously jetted into a column shape.
The main body 3a has a cylindrical shape (the longitudinal section is rectangular), the front a is connected to the hemispherical portion 3c (the longitudinal section is semicircular), and has an injection hole 3f at the center of the back surface d.

  The wing 3b is a member provided so as to run vertically on the outer peripheral surface b of the main body 3a from the top 3u of the hemispherical portion 3c to the back end 3v of the main body 3a, and the direction of the liquid flow 6a is the circumferential direction of the main body 3a. In order to change to f, it curves toward the back end 3v. The blade 3b in the hemispherical portion 3c is also formed into a hemispherical shape as a whole. However, the blade 3b in the hemispherical portion 3c can be omitted as necessary. Since the blade 3b protrudes from the main body 3a, a groove 3d exists between the adjacent blade 3b and the blade 3b.

The hemispherical portion 3c is a portion that is rounded so that the liquid 6 that has entered from the inlet 2a of the pipe 2 smoothly flows into the groove 3d. The pipe 2 is necessary for generating a fluid with a large angular momentum from the jet in the circumferential direction f discharged from the turbine blade type nozzle 3.
The groove 3d is a passage through which the liquid 6 is partitioned by the blade 3b. Since the blade 3b is curved, the liquid flow 6a flowing in the horizontal direction (the central axis direction of the pipe 2) is gradually bent in the vertical direction to become a spiral swirl flow 6a. Go out from 3.
The injection hole 3f is a hole that discharges the air column 6b that is a base of the microbubble. The air column 6b is generated by supplying the gas 5l from the air supply hole 3e provided in the outer peripheral surface b of the main body 3a. The air column 6b exiting from the injection hole 3f flows together with the swirling flow 6c.

In order to divide the flow of the liquid 6 into equal parts, the blades 3b are arranged with the same shape at equal intervals. The blade interval 3g is an interval at which the blades 3b are arranged. In this case, since the number of blades is 6, the blade interval 3g is 60 degrees, but is not limited thereto.
The blade angle 3h determines the size of the blade 3b in the hemispherical portion 3c. The blade angle 3h extends from the center with a certain angle, and extends to the main body 3a while maintaining the same width. Note that, if the blade angle 3h is too large, the path of the liquid 6 is narrowed. For example, the blade angle 3h is preferably about 15 degrees, but is not limited thereto.
The groove depth 3n of the groove 3d serving as the passage for the liquid 6 is the depth of the groove 3d and also the height of the blade 3b. The groove depth 3n can be adjusted to an appropriate depth depending on the size of the turbine blade nozzle 3.

The nozzle length 3i is the total length of the turbine blade type nozzle 3, and is equal to the sum of the blade length 3k which is the length of the main body 3a and the outer radius 3l which is the radius of the hemispherical portion 3c. In addition, the magnitude | size of the turbine blade type nozzle 3 will also differ in an appropriate magnitude | size, if the magnitude | size of the pipe 2 differs.
The nozzle diameter 3 j is the diameter of the turbine blade type nozzle 3. The nozzle diameter 3j is also the diameter of the main body 3a including the portion of the blade 3b, and is also the diameter of the hemispherical portion 3c because it is connected to the main body 3a.

Since the rear c of the wing 3b is curved, the length of the wing 3b itself is longer than the wing length 3k. Further, the blade 3b in the hemispherical portion 3c is not included in the blade length 3k.
The outer radius 3l is the total radius including the portion of the wing 3b of the hemispherical portion 3c, and is also the length vertically descending from the top 3u of the hemispherical portion 3c to the main body 3a. Since the groove 3d exists between the adjacent wings 3b and 3b, the outer radius 3l means a radius when the groove 3d is considered to be filled.

The inner radius 3 m is a radius of a portion connected to the main body 3 a excluding the blade 3 b of the hemispherical portion 3 c. Since the inner radius 3m is spherical from the position corresponding to the groove depth 3n which is the difference from the outer radius 3l, the top 3u of the inner radius 3m coincides with the top 3u of the outer radius 3l.
The hole distance 3o is a distance from the rear end 3v of the turbine blade type nozzle 3 having the injection hole 3f to the position of the air supply hole 3e. For example, a position that is half the blade length 3k is preferable, but is not limited thereto. is not. The air supply holes 3e are preferably provided on the blades 3b through which the liquid 6 does not pass, but the present invention is not limited to this.

The air supply hole 3e and the injection hole 3f are connected inside the turbine blade type nozzle 3, and the gas 5l supplied from the air supply hole 3e provided in the outer peripheral surface b of the turbine blade type nozzle 3 is converted into the turbine blade type nozzle 3. From the injection hole 3f provided in the center of the back surface d of the nozzle.
The hole inner diameter 3p is the diameter of the air supply hole 3e and the injection hole 3f. The size of the hole inner diameter 3p affects the amount of the air column 6b coming out of the injection hole 3f, so it is necessary to adjust it to an appropriate size, and is determined according to the flow rate of the supplied gas 5l. For example, the hole inner diameter 3p is preferably about 2 mm, but is not limited thereto.

  FIG. 5 is a development view showing the shape of one blade 3 b of the turbine blade type nozzle 3, and shows a state in which the blade 3 b is curved on a graph. The horizontal axis of the graph represents the distance from the blade tip (tip of the blade) in the flow direction, and the vertical axis represents the distance in the circumferential direction. The curve drawn by the wing 3b exists in the range from 0 to the wing length 3k. The distance 3q is an arbitrary value between the distance from the blade tip of 0 and the blade length 3k, and the distance 3r is a value when the distance from the blade tip is the blade length 3k.

  The gradient 3s is a gradient at the distance 3q. When the distance 3q is 0, the gradient 3s is also 0 degrees, but the gradient 3s increases as the distance 3q increases. The gradient 3s of the blade 3b is given because it is necessary that the liquid flow 6a follows the flow when the distance 3q is 0, and that the liquid flow 6a is directed in the circumferential direction f at the distance 3r. Although the liquid flow 6a can be turned into the swirl flow 6c by the gradient 3s, the flow in the circumferential direction f becomes larger than the flow in the main flow direction by the blades 3b, and as a result, in the vortex collapse portion 4b of the vortex breakdown nozzle 4 In order to cause vortex breakdown, the gradient 3t at the end of the blade 3b needs to be larger than approximately 55 to 60 degrees. Specifically, for example, the angle between the blade 3b and the circumferential direction f of the main body 3a is 5 to 9 degrees (or 5 to 6 degrees), that is, the gradient 3t at the distance 3r is 81 to 85 degrees (or 84 to 85). However, the present invention is not limited to this.

  The vortex breaking nozzle 4 is an instrument that vortex breaks the air column 6b flowing through the vortex portion 2b of the pipe 2 together with the swirling flow 6c to generate the microbubble 6d, and is integrally connected to the end of the pipe 2. The vortex breaking nozzle 4 includes a contracted flow portion 4a and a vortex breaking portion 4b. The contracted portion 4a is a tube that is tapered, and the wide side is connected to the vortex portion 2b of the pipe 2 and the narrow side is connected to the vortex collapse portion 4b. The narrowing angle (taper angle) 4e of the contracted flow part 4a depends on the size of the pipe 2 and the like, and is selected as necessary. An example of the angle 4e is about 20 degrees, but is not limited to this. The vortex breaking portion 4b is a cylindrical tube that is thinner than the vortex portion 2b of the pipe 2, and one end is connected to the narrow side of the contracted flow portion 4a and the other end is an outlet. The inner diameter 4f of the vortex breaking portion 4b also depends on the size of the pipe 2, and is selected as necessary. The inner diameter 4f is, for example, 0.5 to 1.5 cm, but is not limited thereto.

The liquid 6 flowing in the pipe 2 enters the wide side of the contracted flow portion 4a from the vortex flow portion 2b, and reaches the vortex collapse portion 4b while increasing the flow velocity by decreasing the diameter of the contracted flow portion 4a. The air column 6b that has flowed together with the liquid 6 is made fine at the vortex breakdown part 4b and discharged from the outlet of the vortex breakdown nozzle 4 as microbubbles 6d.
The minimum nozzle diameter at which the vortex breakdown of the vortex breakdown nozzle 4 occurs, that is, the critical nozzle diameter is obtained as follows.

と表される。ここで、Ｒ＝Ｄ／２（＝図４に示す外半径３ｌ）、Ｑはパイプ２に供給される液体６の流量、ρは液体６の密度、ε＝ｒ_e ／Ｒ（ただし、ｒ_e ＝Ｄ_e ／２）、δ＝ｈ／Ｒ（ｈは図４に示す溝深さ３ｎと等しい）、κ＝Ｎ_v Δθ／２π（ただし、Ｎ_v は翼３ｂの枚数、Δθ（rad.）は溝３ｄの角度（溝角））、θ_f は図５に示す勾配３ｔと等しく、α₀ 、α₁ は定数でα₀ ＝０．４、α₁ ＝１である。 Although the details are omitted, the rotational frequency f of the swirling flow 6c generated by the blade 3b of the turbine blade type nozzle 3 is according to Cassidy et. Al., J. Fluid Mech., V.41, pp.727-736, 1970. obtained by the method, since the relationship of _{f e = (D / D e} ) 2 f is between f and f _e is satisfied,

It is expressed. Here, R = D / 2 (= outer radius 3l shown in FIG. 4), Q is the flow rate of the liquid 6 supplied to the pipe 2, ρ is the density of the liquid 6, and ε = r _e / R (where r _e = D _e / 2), δ = h / R (h is equal to the groove depth 3n shown in FIG. 4), κ = N _v Δθ / 2π (where N _v is the number of blades 3b, Δθ (rad.)) Is the angle of the groove 3d (groove angle)), θ _f is equal to the gradient 3t shown in FIG. 5, α ₀ and α ₁ are constants, and α ₀ = 0.4 and α ₁ = 1.

である。ただし、ｕ_e は渦崩壊用ノズル４の出口における流速、ω_e は渦崩壊部４ｂの断面における旋回流６ｃの回転角周波数である。この（２）式に（１）式のｆ_e を代入すると、Γ_e は

と求められる（Cassidy et. al., J. Fluid Mech., V.41, pp.727-736, 1970 を参照。)
。 The circulation number Γ _e in the constricted flow part 4a of the vortex breaking nozzle 4 is

It is. Where u _e is the flow velocity at the outlet of the vortex breaking nozzle 4 and ω _e is the rotational angular frequency of the swirling flow 6c in the cross section of the vortex breaking portion 4b. Substituting f _e in equation (1) into this equation (2), Γ _e becomes

(See Cassidy et. Al., J. Fluid Mech., V.41, pp.727-736, 1970)
.

In FIG. 8, the change of the circulation number Γ _e before the vortex breakdown with respect to θ _f when ε = 1.5 / 4.0 is obtained by changing δ to 0.4 / 2 and 0.9 / 2. Results are shown. However, Γ _cr in FIG. 8 is the critical circulation number Γ _cr = 2.0 (in this swirl type microbubble generator, Γ _{cr ≈2.0} , the average in the case of a more general swirl flow generator A typical value is Γ _cr ≈ 1 / 0.65 (for example, Spall et. Al., Phys. Fluid, 30 (11), pp. 3434-3440, 1987), as shown in FIG. That is, as the groove depth 3n = h increases, the circumferential momentum relative to the axial momentum becomes relatively small. As a result, the greater the groove depth 3n = h, and thus δ, the greater the circulation number Γ _e. Therefore, when the groove depth 3n = h is increased, vortex breakdown is less likely to occur.

When the groove depth 3n = h and θ _f are given, the minimum value of the nozzle radius at which vortex breakdown occurs, that is, the critical nozzle radius ε _cr (ε _cr = _recr / R where the critical radius is _recr ) is Γ By _{setting e} = Γ _cr, it is obtained as _follows . Therefore, by designing the turbine blade type nozzle 3 and the vortex breakdown nozzle 4 so as to satisfy ε> ε _cr , the vortex breakdown nozzle 4 can cause vortex breakdown.

と表される。ただし、ν_w は液体６の動粘性率である。この式においてΓ_e ＝Ｏ（１）であるから、ν_w が小さく、ｆ_e が大きいほど微細なマイクロバブル６ｄが生成されることが分かる。 FIG. 9 shows changes in ε = r _e / R of vortex breakdown nozzle 4 with respect to δ = h / R when vortex breakdown threshold is Γ _cr = 2.0, θ _f is 50 degrees, 60 degrees, The results obtained by changing to 70 degrees, 80 degrees, and 84 degrees are shown. However, κ = 3/4. In FIG. 9, ◯ and × indicate the case where vortex breakdown occurred and did not occur when the experiment was conducted with θ _f = 84 degrees, respectively. Although the details are omitted, the diameter d of the microbubble 6d discharged from the vortex breaking portion 4b of the vortex breaking nozzle 4 due to the classification effect by the swirling flow 6c is

It is expressed. Where ν _w is the kinematic viscosity of the liquid 6. Since Γ _e = O (1) in this equation, it can be seen that the smaller the ν _{w and the} larger the _fe , the finer microbubbles 6d are generated.

となる。したがって、ｆ_e を大きくすることでマイクロバブル６ｄを生成するには高揚程ポンプ（Ｒが小さい）が有利である。 When the power of the pump used to supply the liquid 6 to the pipe 2 is constant, _fe is

It becomes. Therefore, a high head pump (R is small) is advantageous for generating microbubbles 6d by increasing _fe .

  The air supply device 5 is a device that supplies gas 5l to the swirling flow type microbubble generator 1, and is connected to the air supply holes 3e of the turbine blade type nozzle 3, and discharges the air column 6b from the injection holes 3f. The pressure detector 4c and the pressure detector 4d are instruments for detecting the pressure in the vortex breakdown part 4b. The pressure detector 4c is provided on the side connected to the contracted part 4a, and the pressure detector 4d is provided on the outlet side. It has been. The pressure detector 4c and the pressure detector 4d detect the pressure difference and automatically adjust the supply amount of the gas 5l.

  The air supply device 5 includes members such as a cylinder 5a and a piston 5b. The connection between the air supply device 5 and the turbine blade type nozzle 3 and the vortex breakdown nozzle 4 includes an air supply hole 3e and a vent hole 5f, a pressure detector 4c and a high pressure part 5j, and a pressure detector 4d and a low pressure part 5k. This is done by connecting The cylinder 5a is an outer frame of the air supply device 5, and has a substantially cylindrical shape having a hollow portion inside. An example of the size of the cylinder 5a is about 7.0 cm in length and about 2.6 cm in diameter, but is not limited to this.

A vent hole 5f penetrating the side surface of the cylinder 5a is provided on the leading side of the cylinder 5a. One end of the vent hole 5f is connected to the air supply hole 3e by an air supply pipe 5i, and the other end is opened to release gas 5l. If a special gas is used, connect a cylinder.
The hollow part in the cylinder 5a is divided into a high pressure part 5j and a low pressure part 5k by the piston 5b and the diaphragm 5m. The high pressure portion 5j on the leading side is the pressure detected by the pressure detector 4c, and the low pressure portion 5k on the back side is the pressure detected by the pressure detector 4d.
The high pressure part 5j and the low pressure part 5k are provided with an air hole 5g and an air hole 5h, respectively. The air holes 5g and the air holes 5h are normally closed, but the internal air can be extracted by opening them.

  The piston 5b is a member that reciprocates inside the cylinder 5a, and includes a movable portion 5c, a spring 5d, a stopper 5e, and the like. By moving the piston 5b, the amount of the gas 5l supplied to the air supply hole 3e is adjusted. The movable portion 5c is a portion that moves back and forth in the cylinder 5a, and a columnar rear half that partitions the pile-shaped front half that opens and closes the air supply hole 3e, and the high-pressure portion 5j and the low-pressure portion 5k in the cylinder 5a. It consists of parts. When the movable part 5c moves most forward, the tip penetrates through the vent hole 5f and blocks the gas 5l. When the movable part 5c moves most recently, the tip moves away from the vent hole 5f. Pass 5 liters of gas.

The spring 5d controls the movement of the movable part 5c by expanding and contracting, and adjusts the position of the movable part 5c in conjunction with the pressure difference between the high pressure part 5j and the low pressure part 5k. If the pressure of the high pressure part 5j increases, the spring 5d contracts to move the movable part 5c backward, and if the pressure of the low pressure part 5k increases, the spring 5d extends to move the movable part 5c forward.
The stopper 5e is a member that supports the piston 5b by fixing the end of the piston 5b to the rear portion of the cylinder 5a. By pressing with the stopper 5e, the piston 5b is stabilized in the cylinder 5a, the expansion and contraction of the spring 5d works effectively, and the movable part 5c can be moved.
The movable part 5c and the stopper 5e are connected by a spring 5d. By making the movable part 5c and the stopper 5e slide inside the spring 5d, the stability of the part of the spring 5d is maintained and the movable range is increased. Control.

  The air supply device 5 controls the supply of the gas 5l by moving the piston 5b using the pressure difference between the high pressure portion 5j and the low pressure portion 5k. The high pressure part 5j and the low pressure part 5k are connected to the pressure detector 4c and the pressure detector 4d by pipes 5n and 5o, and reflect the pressure of the vortex breaking part 4b of the vortex breaking nozzle 4. Specifically, when vortex breakdown occurs in the vortex breakdown portion 4b between the pressure detector 4c and the pressure detector 4d, the pressure difference between the pressure detector 4c and the pressure detector 4d increases. When the pressure difference between the high pressure portion 5j and the low pressure portion 5k becomes larger than the reaction force of the spring 5d, the piston 5b moves to the right and the vent hole 5f is opened.

  When vortex breakdown does not occur in the vortex breakdown portion 4b between the pressure detector 4c and the pressure detector 4d, the amount of air supplied to the air supply hole 3e is large, and the pressure detector 4c and the pressure detector 4d. In order to control the air supply amount, the position of the piston 5b when the pressures of the high pressure portion 5j and the low pressure portion 5k are balanced is set to a position where the vent hole 5f is closed. deep.

FIGS. 10A and 10B are diagrams showing vortex breakdown in the vortex breakdown nozzle 4. The vortex breakdown nozzle 4 with vortex breakdown (FIG. 10A) and the vortex breakdown nozzle with no vortex breakdown (FIG. 10B). The state of 4 is shown. As shown in FIG. 10A, in the case of vortex breakdown, the air column 6b coming from the contracted flow part 4a vortex collapses near the middle of the vortex collapse part 4b and exits as a microbubble 6d. The pressure at the outlet of the vortex breakdown part 4b is smaller than the pressure at the inlet of the vortex breakdown part 4b.
If the pressure detector 4c detects the pressure at the inlet of the vortex collapse part 4b and the pressure detector 4d detects the pressure at the outlet of the vortex breakdown part 4b, There is a collapse, and the air is supplied as it is.

In the case of no vortex breakdown (FIG. 10B), the air column 6b coming from the contracted flow part 4a does not collapse in the vortex collapse part 4b and does not become the microbubble 6d, so the pressure at the outlet of the vortex collapse part 4b Is almost the same as the pressure at the inlet of the vortex breakdown part 4b. At this time, the pressure detector 4c detects the pressure at the inlet of the vortex collapse portion 4b, the pressure detector 4d detects the pressure at the outlet of the vortex collapse portion 4b, and if there is no pressure difference in the vortex collapse portion 4b, Suppress the air supply and adjust so that vortex collapse occurs.
Thus, if the air supply amount is not appropriate, the air column 6b does not collapse vortex and the microbubble 6d cannot be obtained. Therefore, in the first embodiment, whether or not the vortex collapse is detected. It can be confirmed by the pressure difference, and the air supply amount can be automatically adjusted using the pressure difference as described above.

で与えられる。ここで、ｄ₀ は次の式 (８) 〜（10）から算定される。

ただし、

である。ここで、γは気体５ｌと液体６との界面張力係数である。 Then, the supply amount of the gas 5l the relationship between the diameter d of the (gas flow) Q _a microbubble 6d will be described.
When the bubble diameter generated by the shear applied to the air column 6b attached to the front surface of the vortex breaking nozzle 4 is calculated according to the Hinze scale (diameter d _H in an equilibrium state where the dividing action by pressure and the surface tension are balanced), FIG. As shown. Although details are omitted, the supply amount Q _a of the gas 5 l when the microbubble 6 d is atomized to the Hinze scale d _H is

Given in. Here, d ₀ is calculated from the following equations (8) to (10).

However,

It is. Here, γ is an interfacial tension coefficient between the gas 5 l and the liquid 6.

FIGS. 12, 13 and 14 show the air supply amount Q _a when Γ _e = 2, 3 and 4, respectively.
The ratio between the flow rate Q _w of the supply quantity Q _a liquid 6 when generating Hinze scale microbubbles 6d is expressed by the following equation.

この式はΓ_e 〜２．５の実験における値Ｑ_a ／Ｑ_w 〜０．００５により検証されている（山田ら、流体力学会年会２００５、ＡＭ０５−２４−００２）。 15, 16 and 17 are plots of the ratio between the air supply amount Q _a and the flow rate Q _{w of the} liquid 6 when Γ _e is 2, 3 and 4, respectively. 15, from FIG. 16 and FIG. 17, within the range of f _e> 100 Hz and _{r e <2cm, Q a /} Q w is less dependent on f _e and r _e. When Q _a / Q _w at this time is calculated asymptotically, the following equation is obtained.

This equation is verified by the value Q _a / Q _w ˜0.005 in the experiment of Γ _e ˜2.5 (Yamada et al., Annual Meeting of Fluid Dynamics Society 2005, AM05-24-002).

At the edge of the outlet of the vortex breaking nozzle 4, a sound is generated due to the peeling of the swirling flow 6 c, and this sound is, for example, pasted with fine fibers (for example, cotton-like) on the edge, or the vortex breaking nozzle It is possible to mute by spreading a wire (for example, having a diameter of several millimeters) in the diameter direction at the entrance of the four contracted portions 4a and disturbing the upstream air column 6b.
A specific example of the turbine blade type nozzle 3 will be described. FIG. 18 shows specific examples 1 to 3 of the turbine blade type nozzle 3 and shows the shape of the turbine blade type nozzle 3. Since the number of blades 3b is 6, and the blades 3b are arranged at equal intervals, the blade interval 3g is 60 degrees, the blade angle 3h is 15 degrees, and the gradient 3s is 84 degrees. 3 is common.

  Specific example 1 is a case where the outer radius 3l of the hemispherical portion 3c is 0.85 cm, the blade length 3k is 2.03 cm, and the groove depth 3n is 0.3 cm. The nozzle length 3i is 2.88 cm because it is the sum of the blade length 3k and the outer radius 3l, and the inner radius 3m is 0.55 cm because it is smaller than the outer radius 3l by the groove depth 3n. Since the circumference of the main body 3a is 5.34 cm because the outer radius 3l is 0.85 cm, the blade width is 0.22 cm because the blade angle 3h is 15 degrees, and the groove width is the blade spacing. Since 3 g is 60 degrees, it is 0.89 cm. The circumferential angle of the wing 3b can be expressed by the formula 67.4 × (−0.0369 + 0.780 / (2.11-position)). The position is the distance from the blade tip, and is a value in the range from 0 to the blade length 3k. For example, when the position is 0, the circumferential angle of the blade 3b is 0 degree, and when the position is the blade length 3k, the circumferential angle of the blade 3b is 63.2 degrees.

  Specific example 2 is a case where the outer radius 3l of the hemispherical portion 3c is 1.6 cm, the blade length 3k is 3.82 cm, and the groove depth 3n is 0.5 cm. The nozzle length 3i is 5.42 cm because it is the sum of the blade length 3k and the outer radius 3l, and the inner radius 3m is 1.1 cm because it is smaller than the outer radius 3l by the groove depth 3n. The circumference of the main body 3a is 10.05 cm because the outer radius 3l is 1.6 cm, so the blade width is 0.42 cm because the blade angle 3h is 15 degrees, and the groove width is the blade spacing. Since 3 g is 60 degrees, it is 1.68 cm. The circumferential angle of the blade 3b can be expressed by an expression of 35.8 × (−0.0695 + 0.276 / (3.98−position)). The position is the distance from the blade tip, and is a value in the range from 0 to the blade length 3k. For example, when the position is 0, the circumferential angle of the blade 3b is 0 degrees, and when the position is the blade length 3k, the circumferential angle of the blade 3b is 59.3 degrees.

  Example 3 is a case where the outer radius 3l of the hemispherical portion 3c is 2.1 cm, the blade length 3k is 5.00 cm, and the groove depth 3n is 0.5 cm. The nozzle length 3i is 7.10 cm because it is the sum of the blade length 3k and the outer radius 3l, and the inner radius 3m is 1.6 cm because it is smaller than the outer radius 3l by the groove depth 3n. Since the circumference of the main body 3a is 13.19 cm because the outer radius 3l is 2.1 cm, the blade width is 0.55 cm because the blade angle 3h is 15 degrees, and the groove width is the blade spacing. Since 3 g is 60 degrees, it is 2.20 cm. The circumferential angle of the wing 3b can be expressed by an expression of 27.3 × (−0.0912 + 0.476 / (5.22−position)). The position is the distance from the blade tip, and is a value in the range from 0 to the blade length 3k. For example, when the position is 0, the circumferential angle of the blade 3b is −3.3 degrees, and when the position is the blade length 3k, the circumferential angle of the blade 3b is 56.6 degrees.

19A, 19B and 19C show specific examples 4 to 6 of the shape of the turbine blade type nozzle 3, the shape of the vortex breaking nozzle 4, and the distance from the turbine blade type nozzle 3 to the vortex breaking nozzle 4. FIG. Regarding the turbine blade type nozzle 3, the specific example 4 is the same as the specific example 1, the specific example 5 is the same as the specific example 2, and the specific example 6 is the same as the specific example 3.
Specific example 4 (FIG. 19A) is a case where the outer radius 3l of the turbine blade type nozzle 3 is about 0.85 cm, and the nozzle length of the turbine blade type nozzle 3 is 2.88 cm. Since the turbine blade type nozzle 3 fits in the pipe 2, the inner diameter of the pipe 2 is about 0.85 cm, and the diameter on the inlet side of the vortex breaking nozzle 4 is also about 0.85 cm. When the length of the vortex section 2b between the turbine blade type nozzle 3 and the vortex breaking nozzle 4 is about 1.7 cm and the length of the vortex breaking nozzle 4 is about 2.6 cm, the turbine blade type nozzle 3 The total length of the vortex section 2b and the vortex breakdown nozzle 4 is about 7.18 cm. The shape of the vortex breaking nozzle 4 is such that if the angle 4e in the contracted flow portion 4a is 20 degrees and the inner diameter 4f on the outlet side is 0.5 cm, the inlet side diameter is 0.85 cm. The length such as 4b is determined.

  Specific example 5 (FIG. 19B) is a case where the outer radius 3l of the turbine blade type nozzle 3 is about 1.6 cm, and the nozzle length of the turbine blade type nozzle 3 is 5.42 cm. Since the turbine blade type nozzle 3 fits in the pipe 2, the inner diameter of the pipe 2 is about 1.6 cm, and the diameter on the inlet side of the vortex breaking nozzle 4 is also about 1.6 cm. When the length of the vortex flow part 2b between the turbine blade type nozzle 3 and the vortex breaking nozzle 4 is about 3.2 cm and the length of the vortex breaking nozzle 4 is about 5.0 cm, the turbine blade type nozzle 3 The total length of the vortex section 2b and the vortex breakdown nozzle 4 is about 13.62 cm. The shape of the vortex breaking nozzle 4 is that if the angle 4e in the contracted flow part 4a is 20 degrees and the inner diameter 4f on the outlet side is 1.0 cm, the diameter on the inlet side is about 1.6 cm. The length of the part 4b and the like is determined.

Example 6 (FIG. 19C) is a case where the outer radius 3l of the turbine blade type nozzle 3 is about 2.1 cm, and the nozzle length of the turbine blade type nozzle 3 is 7.10 cm. Since the turbine blade type nozzle 3 fits in the pipe 2, the inner diameter of the pipe 2 is about 2.1 cm, and the diameter on the inlet side of the vortex breaking nozzle 4 is also about 2.1 cm. When the length of the vortex section 2b between the turbine blade nozzle 3 and the vortex breakdown nozzle 4 is about 4.2 cm and the length of the vortex breakdown nozzle 4 is about 7.0 cm, the turbine blade nozzle 3 The overall length of the vortex section 2b and the vortex breakdown nozzle 4 is about 18.3 cm. The shape of the vortex breaking nozzle 4 is that if the angle 4e in the contracted flow part 4a is 20 degrees and the inner diameter 4f on the outlet side is 1.5 cm, the diameter on the inlet side is about 2.1 cm. The length of the part 4b and the like is determined.
The dimensions of the pipe 2 in the specific examples 4 to 6 are examples of preferable numerical values for generating the microbubbles 6d, and the sizes of the turbine blade type nozzle 3 and the vortex breaking nozzle 4 are also determined according to the size of the pipe 2. It needs to be adjusted.

  As described above, in the swirling flow type microbubble generator 1 according to the first example, the turbine blade type nozzle 3 and the vortex breaking nozzle 4 which are constituent elements thereof are linearly arranged. Can be easily and directly connected to existing facilities. Further, since the gas supply device 5 supplies the gas 5 l to the air supply hole 3 e of the turbine blade nozzle 3, the air supply amount is automatically adjusted according to the pressure fluctuation in the vortex breaking portion 4 b of the vortex breaking nozzle 4. The microbubbles 6d can be generated with stable vortex breakdown. Moreover, since the generation mechanism of the microbubble 6d is clear, the microbubble generator 1 can be easily designed according to the performance of the pump used to supply the liquid 6 to the pipe 2.

Next, a swirling flow type microbubble generator according to a second example will be described.
As shown in FIG. 20, the swirling flow type microbubble generator 1 is characterized in that a tapered portion 4h is provided at the tip of the vortex breaking portion 4b of the vortex breaking nozzle 4 and the outlet is widened in a tapered shape. To do. That is, in the vortex breaking nozzle 4 of the microbubble generating device 1 according to the first example, the exit angle 4i that is the tip of the vortex breaking portion 4b is 0 degree, whereas the microbubble generation according to the second example is generated. The vortex breaking nozzle 4 of the apparatus 1 is provided with a tapered portion 4h having a sufficiently large exit angle (taper angle) 4i of the vortex breaking portion 4b. Specifically, the angle 4i is, for example, about 60 degrees or 80 degrees, but is not limited thereto.

In the case of the vortex breaking nozzle 4 of the first example, the air column 6b generated in the vicinity of the center of the swirl flow 6c in the vortex flow portion 2b is increased in flow velocity by the contraction flow portion 4a and finely crushed by the vortex breakup portion 4b. As a result, in the case of the vortex breaking nozzle 4 of the second example, the air column 6b passes through the vortex breaking portion 4b and bubbles are generated in the tapered portion 4h by the Coanda effect. It sticks. The bubbles stuck to the taper portion 4h are sheared or crushed by the swirling flow 6c that continues from the vortex portion 2b, and microbubbles 6d are generated. By sticking to the taper portion 4h in this way, the time during which the bubbles are subjected to shearing becomes longer, and the atomization of the bubbles is promoted.
The Coanda effect is a fluid property that changes the flow direction along the placed object when the object is placed in the flow. The swirling flow 6c enters the tapered portion 4h from the vortex collapse portion 4b. The air column 6b also spreads by spreading in a tapered shape, and bubbles stick to the tapered portion 4h.

The dimensions of the vortex breaking nozzle 4 of the second example are as follows: the inner diameter of the inlet of the contracted flow part 4a (= the inner diameter 2d of the pipe 2), the angle 4e of the contracted flow part 4a, and the inner diameter 4f of the vortex breaking part 4b. Although it is the same as that of the vortex breaking nozzle 4 of the example 1, the length 4 g of the cylindrical vortex breaking portion 4 b is approximately the same as the inner diameter 4 f.
21A, 21B, and 21C are diagrams comparing the generation states of the microbubbles 6d of the swirling flow type microbubble generating device 1 when the shape of the vortex breaking portion 4b is changed.

As shown in FIG. 21A, in the case of the vortex breaking nozzle 4 of the first example, the air column 6b that has flowed from the vortex portion 2b of the pipe 2 to the contracted portion 4a The bubble 6d is generated, but it spreads only in a narrow linear range.
The vortex breaking nozzle 4 shown in FIG. 21B is a case where the entire vortex breaking portion 4b is a tapered portion, but the range of microbubbles 6d generated in the tapered portion is slightly wider than in the case of FIG. 21A. Degree.
In the case of the vortex breaking nozzle 4 shown in FIG. 21C, microbubbles 6d are generated by shearing or crushing the bubbles stuck to the taper portion 4h, so that the microbubbles 6d are spread in a very wide range in a tapered shape.

  22A and 22B show two types of vortex breakdown. In any case, the vortex is unstable and vortex collapse occurs due to the presence of the sudden expansion portion of the tapered portion 4h at the exit of the vortex breakup nozzle 4, but in the vortex collapse shown in FIG. In the minimum cross section, the flow becomes supercritical and the disturbance cannot propagate upstream, whereas in the vortex breakdown shown in FIG. .

  According to the second example, in addition to the same advantages as the first example, the following advantages can be obtained. That is, since the tapered portion 4h is provided at the tip of the vortex breaking portion 4b of the vortex breaking nozzle 4, the swirl flow 6c sticks to the tapered portion 4h. For this reason, the generation efficiency of the microbubbles 6d can be improved, and the ejection direction of the microbubbles 6d can be easily controlled by selecting the angle 4i of the tapered portion 4h.

Next, the swirl type microbubble generator 1 according to the third example will be described.
As shown in FIG. 23, this swirling flow type microbubble generator 1 has a turbine blade type nozzle 3, a vortex breakdown nozzle 4, and an air supply device, as compared with the swirling flow type microbubble generating device 1 according to the first example. The connection method with 5 is different. Specifically, in the swirling flow type microbubble generator 1, the air hole 5f of the air supply device 5 and the air supply hole 3e of the turbine blade type nozzle 3 are connected to the high pressure portion 5j of the air supply device 5 and the vortex collapse. The pressure detector 4c on the inlet side of the vortex breaking portion 4b of the nozzle 4 for use is connected, and the low pressure portion 5k of the air supply device 5 and the pressure detector 4d provided outside the vortex breaking nozzle 4 are connected. It is characterized by automated air supply. The pressure detector 4 c detects the pressure of the air column 6 b passing through the inside of the vortex breaking nozzle 4, and the pressure detector 4 d detects the pressure of the microbubble 6 d outside the pipe 2.
Note that the one end of the air hole 5f of the air supply device 5 and the air supply hole 3e of the turbine blade type nozzle 3 are connected by the air supply pipe 5i as in the first example. The other end of the vent hole 5f is opened to take in the gas 51, but a cylinder or the like is connected when a special gas is used.

Next, a swirl type microbubble generator 1 according to a fourth example will be described.
As shown in FIG. 24, this swirling flow type microbubble generator 1 has a turbine blade type nozzle 3, a vortex breakdown nozzle 4, and an air supply device, as compared with the swirling flow type microbubble generating device 1 according to the first example. The connection method with 5 is different. Specifically, in this swirling flow type microbubble generator 1, the high pressure part 5j of the air supply device 5 is connected to a pressure detector 4d opened to the hydrostatic pressure around the outlet of the vortex breaking nozzle 4, The low pressure part 5k of the air supply device 5 is connected to a pressure detector 4c provided in the air supply hole 3e of the turbine blade type nozzle 3 to automate the supply of air. The pressure detector 4 c detects the pressure of the air column 6 b generated in the turbine blade type nozzle 3, and the pressure detector 4 d detects the pressure of the microbubble 6 d outside the pipe 2. The connection method of the swirl type microbubble generator 1 is simple because it is not necessary to install a pressure detector in the vortex breakdown nozzle 4.

When the pressure difference between the pressure of the internal air column 6b detected by the pressure detector 4c and the pressure of the external microbubble 6b detected by the pressure detector 4d is large, the microbubble 6b is generated efficiently. When the pressure difference is small, the amount of air is too large and the generation of microbubbles 6d is small.
When the pressure difference between the pressure of the internal air column 6b and the pressure of the external microbubble 6b is large, the piston 5b of the air supply device 5 is moved to the right to open the vent hole 5f, and the gas 51 is supplied to the air supply hole 3e. Supply.
On the contrary, when the pressure difference between the pressure of the internal air column 6b and the pressure of the external microbubble 6d is small, the piston 5b of the air supply device 5 is moved to the left to close the vent hole 5f. The amount of gas 5l supplied to 3e is suppressed.

Next, a swirl type microbubble generator 1 according to a fifth example will be described.
As shown in FIG. 25, in this swirling flow type microbubble generator 1, the swirling flow type microbubble generating device 1 according to the first example is that the pipe 2 is replaced with an expansion tube 11 in which the inner diameter 2 d of the inlet 2 a is narrowed. And different. The enlarged tube 11 has a shape in which the inner diameter 11d of the narrow tube portion 11a on the inlet 2a side is small and the inner diameter 11e of the thick tube portion 11c where the turbine blade nozzle 3 and the vortex breaking nozzle 4 are located is large.

As for the enlarged portion 11b extending from the thin tube portion 11a to the thick tube portion 11c, the inner diameter smoothly increases in an arc shape like two dotted circles shown in FIG. 25, and the rear portion of the enlarged portion 11b is a turbine blade. The shape is along the hemispherical portion 3 c of the mold nozzle 3. By smoothly expanding the enlarged portion 11b, the flowing water cross-sectional area does not increase rapidly when the liquid 6 flows through the enlarged tube 11, so that the turbine blade type nozzle 3 moves the liquid flow 6a from the axial direction of the enlarged tube 11 to the circumferential direction. can be effectively converted to f.
In the swirling flow type microbubble generator 1, the linear liquid flow 6a supplied to the inlet 2a of the expansion tube 11 from a liquid feed pump such as a water feed pump is efficiently converted into a spiral swirl flow 6c. Moreover, the influence of the contraction flow by the turbine blade type nozzle 3 is reduced, and the energy loss is reduced.
According to the fifth example, in addition to the same advantages as the first example, it is possible to obtain the advantage that the generation efficiency of the microbubbles 6d can be improved.

Next, a swirl type microbubble generator according to a seventh example will be described.
FIG. 26 and FIG. 27 show the spectrum of the sound wave and the spectrum of the image measured in order to confirm the generation state of the microbubble 6d of the swirling flow type microbubble generator 1, respectively. This shows that the rotational frequency of the swirling flow 6c can be predicted by measuring the sound (vortex whistle) generated when vortex breakdown occurs.

  The sound wave spectrum shown in FIG. 26 is a graph obtained by measuring the frequency of the sound generated by the swirling flow 6c by a hydrohorn capable of receiving sound propagating in the liquid. The spectrum of the image shown in FIG. It is the graph which measured the rotational frequency of the swirl flow 6c by the video image | video. However, the nozzle diameter 3j of the turbine blade type nozzle 3 is 4 cm, the inner diameter 4f of the vortex breaking portion 4b of the vortex breaking nozzle 4 is 1 cm, and the flow rate of water used as the liquid 6 is 700 cc / s.

  As shown in FIGS. 26 and 27, both the frequency in the sound wave spectrum and the frequency in the image spectrum are characterized by the value of the power spectrum at about 460 Hz. In the sound wave spectrum shown in FIG. 26, a peak appearing in the vicinity of 520 Hz on the right side of about 460 Hz indicates the generation state of the microbubble 6d. The power spectrum represents the mean square value of the vibration amount as a distribution of frequency components.

  According to the sixth example, whether or not the microbubbles 6d are generated efficiently can be confirmed by measuring the underwater sound without directly viewing the image of the microbubbles 6d. Instead of detecting the pressure of the vortex breakdown nozzle 4 as in the example of 5, it is possible to adjust the amount of gas 5l supplied to the air supply hole 3e only by measuring sound waves. Further, even when the liquid 6 is opaque, it is possible to easily grasp the generation state of the microbubbles 6d.

Next, a swirl type microbubble generator according to a seventh example will be described.
The swirling flow type microbubble generator 1 is characterized in that the edge of the outlet of the vortex breaking nozzle 4 is smoothed.
28A is an enlarged view of the vortex breaking nozzle 4 and FIG. 28B is an enlarged view of the edge 4k at the outlet of the vortex breaking nozzle 4. FIG.

By smoothing the edge 4k at the outlet of the vortex breaking nozzle 4, the air column 6b sticks to the front surface of the vortex breaking nozzle 4 (Coanda effect), and the air column 6b is crushed by shearing by the swirling flow 6c, Bubble 6d is generated. Further, the microbubbles 6d are dispersed in a wide range on the front surface of the vortex breaking nozzle 4. In order for the air column 6b to stick to the front surface of the vortex breaking nozzle 4, the centrifugal force generated by the swirling flow 6c needs to be larger than the centrifugal force in the main flow direction. Therefore, when the curvature radius of the edge 4k and [rho _{e,
ρ e ~ (u e / v} e) 2 r e = Γ e -2 r e (14)
It is necessary to do it above. Where v _e is the circumferential velocity of the swirling flow 6 c at the outlet of the vortex breaking nozzle 4. That is,
^{_{ρ e ≧ Γ e -2 r e}} (15)
And
The angle θ ₀ formed by the tubular vortex breaking portion 4b of the vortex breaking nozzle 4 and the front surface of the tapered portion 4h determines the direction in which the microbubbles 6d are ejected from the outlet of the vortex breaking nozzle 4.

FIG. 29 shows the case of supercritical vortex breakdown, which is Γ _{e to} Γ _cr . FIG. 30 shows the case of subcritical vortex breakdown, where Γ _e > Γ _cr .
FIGS. 31A, 31B, and 31C are the cases of θ _{0 to} 100 degrees, θ _{0 to} 90 degrees, and θ _{0 to} 45 degrees, respectively, and in any example, the swirl flow is caused by the curvature of the edge 4k at the exit of the vortex breaking nozzle 4 6c adheres to the front surface of the vortex breaking nozzle 4 and flows in the tangential direction of the front surface.

A swirl type microbubble generator according to an embodiment of the present invention will be described based on the above swirl type microbubble generator 1. In this swirling flow type microbubble generating device, the same or corresponding parts as those of the swirling flow type microbubble generating device 1 are denoted by the same reference numerals.
32A, B, and C show three installation forms of the pressure blocking nozzle in the swirling flow type microbubble generator according to this embodiment.

  In the installation form (type A) shown in FIG. 32A, coaxially with the vortex breakdown nozzle 4 on the downstream end face P1 side of the vortex breakdown portion 4b of the swirl flow type microbubble generator 1. In addition, a pressure blocking nozzle 21 is installed facing the vortex breaking part 4b. In this case, the outer shape of the vortex breaking nozzle 4 has a cylindrical shape. The outer shape of the pressure blocking nozzle 21 is also cylindrical, and has the same diameter as the diameter of the outer periphery of the vortex collapse portion 4b. The vortex breaking portion 4b has a cylindrical shape and a jet port Q of the microbubble 6d. A gap 22 is formed between the end face P1 on the downstream side of the vortex breaking portion 4b and the end face P2 on the upstream side of the pressure blocking nozzle 21. The interval of the gap 22 gradually increases linearly from the central axis of the vortex breaking nozzle 4 and the pressure blocking nozzle 21 in the radial direction. The portion of the pressure blocking nozzle 21 that faces the jet port Q is configured to block the low pressure portion at the center of the swirling flow coming out of the jet port Q from the downstream side of the pressure blocking nozzle 21. ing. In other words, in this case, a through hole is not provided in the portion of the pressure blocking nozzle 21 that faces the ejection port Q. Further, the portion of the pressure blocking nozzle 21 that faces the ejection port Q does not penetrate into the vortex collapse portion 4b, more specifically, the ejection port Q. In this case, a gas-liquid mixed phase flow (for example, a mixed phase flow such as water and air) is ejected from the jet outlet Q of the vortex breaking portion 4b, microbubbles are generated at the edge 4k and the tapered portion 4h, and the outside through the gap 22 Microbubbles are released into (liquid such as water).

In the installation form (type B) shown in FIG. 32B, the swirl flow type microbubble generator 1 has a vortex breaking nozzle 4 on the downstream end face P1 side of the vortex breaking portion 4b and coaxial with the vortex breaking nozzle 4. In addition, a pressure blocking nozzle 21 is installed facing the vortex breaking part 4b. These vortex breaking nozzle 4 and pressure blocking nozzle 21 are accommodated in the pipe 2. In this case, the outer shape of the vortex breaking nozzle 4 has a cylindrical shape. The outer shape of the pressure blocking nozzle 21 is also cylindrical, and has the same diameter as the diameter of the outer periphery of the vortex collapse portion 4b. The vortex breaking portion 4b has a cylindrical shape and a jet port Q of the microbubble 6d. A gap 22 is formed between the end face P1 on the downstream side of the vortex breaking portion 4b and the end face P2 on the upstream side of the pressure blocking nozzle 21. The interval of the gap 22 gradually increases linearly from the central axis of the vortex breaking nozzle 4 and the pressure blocking nozzle 21 in the radial direction. A plurality of grooves 21 a parallel to the central axis of the pressure blocking nozzle 21 are typically provided at equal intervals in the circumferential direction on the outer peripheral surface of the pressure blocking nozzle 21. The outer diameter is equal to the inner diameter of the pipe 2. When the depth of the groove 21a is d and the length of the groove 21a is h, the aspect ratio of these grooves 21a is h / d> 1. The portion of the pressure blocking nozzle 21 that faces the jet port Q is configured to block the low pressure portion at the center of the swirling flow coming out of the jet port Q from the downstream side of the pressure blocking nozzle 21. ing. In other words, in this case, a through hole is not provided in the portion of the pressure blocking nozzle 21 that faces the ejection port Q. Further, the portion of the pressure blocking nozzle 21 that faces the ejection port Q does not penetrate into the vortex collapse portion 4b, more specifically, the ejection port Q. In this case, a gas-liquid mixed phase flow (for example, a mixed phase flow of water and air) is ejected from the jet outlet Q of the vortex collapse portion 4b, microbubbles are generated at the edge 4k and the tapered portion 4h, pass through the gap 22, Microbubbles are discharged to the outside (in the air or a pipe) through the space between the pipe 2 and the groove 21 a formed on the outer peripheral surface of the pressure blocking nozzle 21.
Instead of forming the groove 21 a on the outer peripheral surface of the pressure blocking nozzle 21, a plurality of holes 21 b parallel to the central axis of the pressure blocking nozzle 21 are formed in a portion adjacent to the inner peripheral surface of the pressure blocking nozzle 21. May be provided at regular intervals in the circumferential direction. In this case, when the inner diameter of the hole 21b is d and the length of the hole 21b is h, the aspect ratio of these holes 21b is h / d> 1.

  In the installation mode (type C) shown in FIG. 32C, the vortex breaking nozzle 4 is coaxial with the vortex breaking nozzle 4 on the downstream end face P1 side of the vortex breaking portion 4b of the swirling flow type microbubble generator 1. In addition, a pressure blocking nozzle 21 is installed facing the vortex breaking part 4b. These vortex breaking nozzle 4 and pressure blocking nozzle 21 are accommodated in the pipe 2. In this case, the outer shape of the vortex breaking nozzle 4 has a cylindrical shape. The pressure blocking nozzle 21 has a shape that swells from upstream to downstream, and the upstream portion has the same diameter as the outer periphery of the vortex collapse portion 4b. The vortex breaking part 4b has a spout Q of a cylindrical microbubble 6d. A gap 22 is formed between the end face P1 on the downstream side of the vortex breaking portion 4b and the end face P2 on the upstream side of the pressure blocking nozzle 21. The interval of the gap 22 gradually increases linearly from the central axis of the vortex breaking nozzle 4 and the pressure blocking nozzle 21 in the radial direction. The pressure blocking nozzle 21 communicates with a gap 22 adjacent to the inner wall of the pipe 2 and a downstream end surface P3 of the pressure blocking nozzle 21, and merges with each other at the end surface P3. A plurality of holes 21b are provided. When the inner diameter of the hole 21b is d and the length of the hole 21b is h, the aspect ratio of these holes 21b is h / d> 1. In this case, a gas-liquid mixed phase flow (for example, a mixed phase flow of water and air) is ejected from the jet outlet Q of the vortex collapse portion 4b, microbubbles are generated at the edge 4k and the tapered portion 4h, pass through the gap 22, Microbubbles are discharged to the outside (in the air or in water (generally in liquid)) through the hole 21b of the pressure blocking nozzle 21.

According to the above-described types A to C, the following effects (a) to (c) can be obtained.
(A) Noise accompanying generation of sound waves can be reduced.
The generation of sound waves causes noise problems when the swirling flow type microbubble generator is used for consumer goods or water quality improvement, and the sound waves generated from the swirling flow type microbubble generator are formed in the swirling frequency and inside the device. There are two types of vibrations, the natural frequency of the air column. According to the types A to C, the pressure blocking nozzle 21 is installed on the downstream side of the vortex breakdown nozzle 4, so that the vortex breakdown can be changed from the spiral type to the bubble type. The bubble-type vortex collapse has a small external force to expand and contract the air column, so the air column sound is reduced. Further, since the pressure blocking nozzle 21 is fixed to the downstream end face P1 side of the vortex breaking nozzle 4, the turbulence of the swirling flow 6c is reduced, and the above-described swirling sound and air column noise are reduced.

(B) It is possible to prevent re-suction of the released fluid when released in water.
It is possible to prevent the floc from being broken and dispersed in the liquid by re-inhaling the released fluid when the floc is floated and separated by microbubbles. That is, according to the types A to C, the microbubble water discharged by the pressure blocking nozzle 21 is not re-sucked.
(C) Re-foaming of the dissolved gas due to the generation of the low-pressure part at the center of the swirling flow can be prevented.
In the swirl type microbubble generator, the pressure at the center of the swirl flow decreases, and this decrease in gas pressure means that dissolved gas precipitates as a gas simultaneously with the reduction of the generated bubble diameter. According to the types A to C, the pressure at the jet outlet Q of the vortex collapse part 4b can be increased by providing the contracted part by installing the pressure blocking nozzle 21.

According to types B and C, the following effects (d) and (e) can be obtained.
(D) It is possible to prevent the generation of fine bubbles due to the suction of air when released into the air.
This is important for the realization of an air radiating water jet nozzle containing microbubbles. When the downstream end face P1 of the vortex breaking nozzle 4 is in contact with the atmosphere, the air in the atmosphere is sucked in due to the negative pressure at the center, and a liquid film sheet is generated. According to types B and C, the low pressure part of the flow on the downstream end face P1 of the vortex breaking nozzle 4 can be shielded by the pressure blocking nozzle 21 and the groove 21a of the pressure blocking nozzle 21 is vortex collapsed. By providing at a position away from the central axis of the nozzle 4 in the radial direction, fine bubbles and jets can be generated.

(E) It is possible to prevent a reduction in bubble generation efficiency due to swirling of the entire liquid when installed in the middle of a pipeline.
In the case where only a space as large as the outer diameter of the vortex breaking nozzle 4 can be formed on the downstream end face P1 side of the vortex breaking nozzle 4, the efficiency of generating fine bubbles is lowered, and thus a device is required. That is, the flow that has passed through the swirling flow type microbubble generator excites the entire swirling flow in the pipe, and the energy of the swirling flow generated by the swirling flow type microbubble generating device is used to generate this swirling flow. In addition, the generation of vortices downstream of the swirl type microbubble generator causes bubbles to stay in the pipe and causes coalescence of fine bubbles. According to types B and C, the pressure blocking nozzle 21 can prevent the generation of vortices and the generation of swirling flow downstream of the swirling flow type microbubble generator.

The shape of the pressure blocking nozzle 21 will be described in detail again with the example shown in FIGS. 33A and 33B as an example.
The shape of the pressure blocking nozzle 21 satisfies the following conditions 1 to 4.
<Condition 1>
The end face P2 on the vortex breaking nozzle 4 side of the pressure blocking nozzle 21 depends on the shape of the end face P1 of the vortex breaking portion 4b of the vortex breaking nozzle 4, and the vortex breaking nozzle 4 and pressure blocking nozzle shown in FIG. The interval of the gap 22 in the direction parallel to the central axis of the nozzle 21 gradually increases linearly (outward) from the central axis in the radial direction.

<Condition 2>
A through hole is not provided in a portion of the pressure blocking nozzle 21 that faces the jet port Q of the vortex breaking nozzle 4.
<Condition 3>
The upstream end face P <b> 2 of the pressure blocking nozzle 21 does not penetrate into the vortex breaking portion 4 b of the vortex breaking nozzle 4, more specifically, the jet outlet Q.
<Condition 4>
The aspect ratio h / d> 1 of the groove 21a of the pressure blocking nozzle 21 is satisfied.

The inventor has determined that the apex angle θ _SU of the upstream end face P 2 of the pressure blocking nozzle 21, and the vortex breaking nozzle 4 and the pressure blocking nozzle on the central axis of the vortex breaking nozzle 4 and the pressure blocking nozzle 21. It was found that the pressure in the air column can be minimized, in other words, the suction pressure can be maximized, by appropriately selecting the interval t (see FIGS. 33A and B) with respect to 21. Specifically, the optimum value of the apex angle θ _SU of the end face P2 of the pressure blocking nozzle 21 and the interval t is approximately given by the following equation.
θ _SU ≦ θ _VB , t ≒ D _e / 4 (16)
Here, the theta _VB apex angle of the end face P1 of the downstream side of the vortex breakdown section 4b of the vortex breakdown nozzle 4, D _e is the diameter of the spout Q. The gap 22 increases in the radial direction from the central axis of the vortex breaking nozzle 4 and the pressure blocking nozzle 21, but this causes the low pressure position in the flow at the jet outlet Q of the vortex breaking portion 4 b to move upstream. It is known that the effect of sucking out the flow can be obtained (the principle of the diffuser).

となる。この場合には、上記の（ａ）〜（ｅ）の効果を得ることができる。ただし、この場合には流れの抵抗が大きいため、高揚程ポンプを用いる必要がある。また、旋回流型マイクロバブル発生装置１からの給気は困難となる。このＳ１に示す状態では、渦崩壊部４ｂの噴出口Ｑにおいて気体の加圧が促進され、間隙２２を通過するに伴って溶解気体の再気泡化が促進される。 As a result of the study by the present inventor, when the opening angle Δθ≡θ _VB −θ _{SU of} the gap 21 is 10 ° to 20 °, the pressure in the air column becomes the lowest. When Δθ is larger than 20 °, the gradually expanded flow in the gap 21 becomes unstable due to the occurrence of separation or the like, and conversely, the amount of decrease in the air column pressure decreases.
FIG. 34 schematically shows a qualitative relationship between the distance t between the vortex breaking nozzle 4 and the pressure blocking nozzle 21 and the air column pressure (suction pressure), the generated sound pressure, and the nozzle resistance. .
S1 to S4 in FIG. 34 correspond to FIGS. 35A to 35D, respectively. In the state of S1 shown in FIG. 35A, the interval t between the vortex breaking nozzle 4 and the pressure blocking nozzle 21 is extremely small, and the pressure deficit when the fluid passes through the gap 22 becomes larger than the pressure increase due to the swirling flow. As will be described in detail later, this interval t is approximately

It becomes. In this case, the effects (a) to (e) can be obtained. However, in this case, since the flow resistance is large, it is necessary to use a high head pump. In addition, it is difficult to supply air from the swirl type microbubble generator 1. In the state shown in S <b> 1, the pressurization of the gas is promoted at the spout Q of the vortex breaking portion 4 b, and the re-bubbled dissolved gas is promoted as it passes through the gap 22.

In the state of S2 shown in FIG. 35B, the flowing water resistance and the air column pressure are minimized, and the generated sound is small. T < _De / 4 (18) as a condition that no suction flow occurs at the outlet of the swirl type microbubble generator 1
Is mentioned. On the other hand, the interval t is of the same order as the minimum cross-sectional area of the outlet of the swirl type microbubble generator 1 so that the resistance of the gap 22 can be ignored compared to the resistance of the swirl type microbubble generator 1. It has become. This can be seen from πD _e ² / 4≈t · πD _e . The optimum value of this interval t (the position where the pressure in the air column is minimum) is t≈D _e / 4 (19)
It is. In this case, the effects (a), (b), (d), and (e) can be obtained. In the state of S2, bubble collapse is promoted.

In the state of S3 shown in FIG. 35C, the air column adheres to the pressure blocking nozzle 21. in this case,
_De / 2 <t < _De (20)
It is. In this case, the pressure in the air column does not decrease, and the microbubble generation efficiency decreases. In this case, the effects (a), (b), (d), and (e) can be obtained.

In the region of S4 shown in the figure, the air column adheres to the end face P1 on the downstream side of the vortex breaking nozzle 4, and the generated sound is large.
t> 2D _e (21)
In this case, the effects (b), (d), and (e) described above can be obtained. When the sound generated by the swirling flow type microbubble generator does not matter, this arrangement does not reduce the bubble generation efficiency.

Next, the result of verifying the effect of the pressure blocking nozzle 21 will be described.
In Experiment I, regarding the pressure in the air column and the sound pressure of the generated sound when the apex angle θ _SU of the end face P2 of the pressure blocking nozzle 21 and the interval t are changed, the pressure in the air column is t≈D _e / 4. It shows that the minimum value is taken and the generated sound is reduced. In Experiment II, the interval t was changed in detail, and it was verified that the air column pressure had a minimum value.

<Experiment I>
36A and B show a schematic of the experimental apparatus used. The experiment was performed using the following two types of swirl type microbubble generators.
(1) A turbine blade type nozzle 3 for high swirl flow with three blades 3b and a small depth of the groove 3d and a vortex breaking nozzle 4 with an apex angle θ _{VB of the} end face P1 of θ _VB = 240 ° The swirl flow type microbubble generator having is used.
(B) A turbine blade type nozzle 3 for intermediate swirling flow with five blades 3b and a large depth of the groove 3d and a vortex breaking nozzle 4 with an apex angle θ _{VB of the} end face P1 of θ _VB = 180 °. The swirl flow type microbubble generator having is used.

(Ia) Air column pressure (suction pressure)
First, the air column pressure was measured with no air supply. Shows D _e = 5 mm in (1), the water flow rate Q _w = 5L / min, the results when the circulation number gamma _e = 1.9 in FIG. 37. As shown in FIG. 37, the suction pressure becomes maximum when the interval t is smaller than 1 mm, and decreases as the interval t increases. FIG. 38 shows the results when D _e = 6.5 mm, water flow rate Q _w = 10 L / min, and circulation number Γ _e = 2.3 in (2). As shown in FIG. 38, the suction pressure becomes maximum when the interval t is about 1 mm. When the interval t increases, the suction pressure decreases once but then increases and gradually approaches a certain value. In either case (1) or (2), Δθ≡θ _VB −θ _SU = 10 ° to 20 ° (22)
It can be seen that there is an interval t at which the suction pressure is maximized.

(1b) Sound pressure It is shown that the sound pressure can be reduced by providing the pressure blocking nozzle 21 on the downstream side of the vortex breaking nozzle 4.
Two types of sound waves are mainly emitted from the swirl type microbubble generator. FIG. 39 shows the relationship between the swirling frequency and the natural frequency of the air column and the interval t when the turbine blade type nozzle 3 having five blades 3b is used and no air is supplied. These swirl frequencies and natural frequencies do not depend on the position of the pressure blocking nozzle 21 and the apex angle θ _SU as much as the difference. On the other hand, the figure shows how the energy of each sound wave changes with the interval t. It can be seen that the energy of the sound wave when the interval t is 2 mm or less is about 1/10 of the value when the interval t is large. Further, when θ _SU = 160 ° (Δθ = 20 °), sound wave attenuation is the largest. Further, it can be seen that when the interval t is 2 mm, the shielding of the sound wave emitted from the vibration of the air column is significant. It can be seen that this method particularly reduces air column noise.

Next, the result of obtaining the energy of the sound wave when the interval t is fixed to 1 mm and the air supply amount Q _a is changed will be described. The results are shown in FIGS. 42 and 43, it can be seen that the pressure blocking nozzle 21 having the suction effect has a smaller sound pressure, and that the effect of attenuating the sound pressure is maintained even if the air supply amount Q _a is increased. .

<Experiment II>
The experiment was performed using the vortex breaking nozzle 4 with θ _VB = 160 ° and D _e = 8 mm and the pressure blocking nozzle 21 with θ _SU = 140 ° and diameter D = 40 mm. The flow rate Q _w of water is 20L / min, Kyukiryou Q _a is 100cc / min.
FIG. 44 shows the pressure in the air column (suction pressure), and FIG. 45 shows the change in the pump flow rate with the interval t. 44 and 45, it can be seen that when the interval t is about 2 mm, the suction pressure becomes maximum, and at the same time, the pump flow rate is larger than t˜2D _e . An increase in pump flow indicates a decrease in fluid resistance.
Figure 46 shows the spectrum of _{t = 2.2mm (t ≒ D e} / 4) and t = generated sound in 15mm (t~2D _e). From FIG. 46, when the spectrum of the sound wave changes greatly depending on the interval t, that is, the position of the pressure cutoff nozzle 21 with respect to the vortex breaking nozzle 4, when t≈D _e / 4, the suction pressure takes the minimum value and the sound pressure is obtained. Can be seen to decrease. The sound pressure is reduced because the shape of the air column on the downstream side of the vortex breaking nozzle 4 has changed.

Next, a usage form of the pressure blocking nozzle 21 in the swirling flow type microbubble generator in the air, in the pipeline, and in water will be described.
First, the case where the above-mentioned type A (FIG. 32A) is used in water is demonstrated.
When the downstream end face P1 of the vortex breaking nozzle 4 has a sufficient spread and the swirling flow spreads in the radial direction, it is not necessary to provide a hole in the pressure blocking nozzle 21. At this time, the fluid flows out in the radial direction (FIG. 32A). In this case, the pressure blocking nozzle 21 is installed for the purpose of reducing the sound pressure of the sound wave. Further, since the sound wave is radiated from the end face P1 on the downstream side of the vortex breaking nozzle 4, it is effective to manufacture the pressure blocking nozzle 21 with a material that does not transmit the sound wave or to have a certain thickness.

Next, the case where the above-mentioned type B (FIG. 32B) is used in a pipe line is demonstrated.
It prevents the swirling flow from being formed downstream of the swirling flow type microbubble generator and simultaneously reduces sound waves. The groove 21a of the pressure blocking nozzle 21 is set to a <h (a is the width of the groove 21a) so that a swirling flow is not formed downstream (see FIGS. 47A and B). The distance in the radial direction of the groove 21a, in other words, the depth d is set so as not to reach the spout Q of the vortex breaking nozzle 4. In particular, the total flow cross-sectional area of the groove 21a is increased so that the resistance of the groove 21a is sufficiently smaller than the resistance of the swirl type microbubble generator.

Next, the case where the above-described type C (FIG. 32C) is used for aerial radiation will be described.
The radius of the pressure blocking nozzle 21 is preferably large so that the swirl flow on the downstream end face P1 of the vortex breaking nozzle 4 spreads. Further, the entire flowing water cross-sectional area of the groove 21a is increased so that the resistance of the groove 21a is sufficiently smaller than the resistance of the swirling flow type microbubble generator. Although the thickness of the pressure blocking nozzle 21 is determined as appropriate, the thicker the radiation of the sound wave to the outside decreases. Since a through hole cannot be provided near the center of the pressure blocking nozzle 21 (atmosphere is sucked into the air column), the thickness of the pressure blocking nozzle 21 is increased to provide a hole 21b in the pressure blocking nozzle 21. A water jet can be generated by making a flow path consisting of the above and controlling the direction of the jet, or by joining the flow path made of these holes 21b at the downstream end face P3 of the pressure blocking nozzle 21.

Next, a swirl type microbubble generator capable of generating microbubbles at a high concentration will be described.
FIG. 48 shows a pressure-dissolving swirl type microbubble generator using a high head pump. As shown in FIG. 48, a swirl type microbubble generator 102 for supplying air is attached to the suction port of the high head pump 101. By attaching the pressure blocking nozzle 21 to the end face P1 on the downstream side of the vortex breaking nozzle 4 of the swirling flow type microbubble generator 102, the liquid passing through the high head pump 101 does not swirl, and the supplied gas is fine. Turn into. Further, the gas that has passed through the high head pump 101 is pressurized and melted by the head of the high head pump 101, and the pressure is reduced by the swirl type microbubble generator 103 attached to the outlet of the high head pump 101 to re-bubble. . The pressure blocking nozzle 21 attached to the end face P1 on the downstream side of the vortex breaking nozzle 4 of the swirling flow type microbubble generator 103 reduces the generated sound. In the case of the equation (17) with a small interval t, the pressure effect increases while the flow resistance increases. At _De / 8/8 <t < _De / 4, there is no pressurizing effect, but the flow resistance is reduced and re-foaming is promoted. The position of the pressure blocking nozzle 21 is determined according to the performance of the high head pump 101.

である。ここで、Ｕは流速、ｒは渦崩壊用ノズル４および圧力遮断用ノズル２１の中心軸からの放射方向距離、ζ（ｒ）は流速の大きい流体層の厚さである。上式から

である。したがって、図３４に示すＳ３、Ｓ４の状態は

である。ζ（ｒ）の最大値はｒ＝Ｄ_e ／２より、渦崩壊用ノズル４の下流側の端面Ｐ１のすべての領域で式（２５）が満たされるためには

が必要である。式（２６）は前記の式（２０）、（２１）に対応する。 Next, the three cases shown in FIGS. 49 to 51 are classified based on the physical phenomenon, and the optimum value of the interval t between the vortex breaking nozzle 4 and the pressure blocking nozzle 21 is obtained according to the governing equation of the fluid. .
In the case shown in FIG. 49 (states S3 and S4 shown in FIG. 34), the flow in front of the outlet of the vortex breaking nozzle 4 of the swirling flow type microbubble generator satisfies the condition that the pressure is almost constant. It becomes constant (Bernoulli's theorem). The thickness of the fluid layer on the downstream end face P1 of the vortex breakdown nozzle 4 is calculated from a continuous equation (conservation law of volume flow rate).

It is. Here, U is the flow velocity, r is the radial distance from the central axis of the vortex breaking nozzle 4 and the pressure blocking nozzle 21, and ζ (r) is the thickness of the fluid layer with a large flow velocity. From the above formula

It is. Therefore, the states of S3 and S4 shown in FIG.

It is. Since the maximum value of ζ (r) is r = D _e / 2, in order for Expression (25) to be satisfied in all regions of the end face P1 on the downstream side of the vortex breakdown nozzle 4,

is necessary. Expression (26) corresponds to the above expressions (20) and (21).

である。間隔ｔは、渦崩壊用ノズル４の下流側の端面Ｐ１のすべての領域で式（２７）が満たされる場合には

渦崩壊用ノズル４の下流側の出口のみで満たされるとすれば

である。一般的には式（２９）が満たされると、前記の流体層が破壊され流体は平均的に渦崩壊用ノズル４と圧力遮断用ノズル２１とで囲まれた領域を流れると考えられ、このときｒ方向の流速はｖ_r は

で与えられる。ここで、Ｑは流量、Ｓは流水断面積である。また、旋回流は旋回方向の運動方程式

から算定される。ここで、ｆは抵抗係数で滑面乱流の場合には近似的に

で与えられる。ただし、Ｒ_e は渦崩壊用ノズル４と圧力遮断用ノズル２１との間の流れのレイノルズ数、νは動粘性係数である。一方、粗面乱流の場合には抵抗係数は

で与えられる。ここで、ｋ_S は相当粗度である。 Next, in the case shown in FIG. 50 (states S1 and S2 shown in FIG. 34), the flow velocity in front of the outlet of the vortex breaking nozzle 4 of the swirling flow type microbubble generator is pressure-blocked with the vortex breaking nozzle 4. It is determined by the interval t with the nozzle 21 for use (the interval is smaller than the thickness of the fluid layer). That is,

It is. The interval t is when the expression (27) is satisfied in all the regions of the end face P1 on the downstream side of the vortex breaking nozzle 4.

If it is filled only with the outlet on the downstream side of the vortex breaking nozzle 4

It is. In general, when the equation (29) is satisfied, the fluid layer is broken, and the fluid is considered to flow in an area surrounded by the vortex breakdown nozzle 4 and the pressure cutoff nozzle 21 on average. The flow velocity in the r direction is v _r

Given in. Here, Q is a flow rate, and S is a flowing water cross-sectional area. The swirling flow is the equation of motion in the swirling direction.

Calculated from Here, f is a resistance coefficient and is approximately in the case of smooth surface turbulence.

Given in. However, R _e is the Reynolds number of the flow between the vortex breakdown nozzle 4 and the pressure shut-off nozzle 21, [nu is the kinematic viscosity. On the other hand, in the case of rough surface turbulence, the resistance coefficient is

Given in. Here, k _S is a substantial roughness.

となる。ただし、Ω_e は渦崩壊用ノズル４の出口における角速度である。また、圧力遮断用ノズル２１の頂角θ_SUが１８０°に近いときのｒ方向の運動方程式から圧力勾配ｄＰ／ｄｒは

で与えられる。式（３５）の右辺第一項は流体の減速による圧力勾配、第二項は遠心力、第三項は運動量損失勾配である。式（３０）を式（３５）に代入すると、ｒ方向の圧力は流体の慣性により増加し摩擦により減少することが分かる。すなわち、Ｓ２で示される状態においては、渦崩壊用ノズル４の出口の圧力が極小値をとるためには、渦崩壊用ノズル４の下流側の端面Ｐ１のすべての領域でｄＰ／ｄｒ＞０となる必要がある。また、Ｓ１で示される状態においては、渦崩壊用ノズル４の出口の圧力が極大値をとるためには、渦崩壊用ノズル４の下流側の端面Ｐ１でｄＰ／ｄｒ＜０となる必要がある。 For simplicity, if you ignore the resistance in the turning direction, the law of conservation of angular momentum (ignoring momentum loss)

It becomes. Here, Ω _e is an angular velocity at the outlet of the vortex breakdown nozzle 4. Further, from the equation of motion in the r direction when the apex angle θ _SU of the pressure blocking nozzle 21 is close to 180 °, the pressure gradient dP / dr is

Given in. The first term on the right side of Equation (35) is the pressure gradient due to the deceleration of the fluid, the second term is the centrifugal force, and the third term is the momentum loss gradient. Substituting equation (30) into equation (35), it can be seen that the pressure in the r direction increases due to the inertia of the fluid and decreases due to friction. That is, in the state shown by S2, in order for the pressure at the outlet of the vortex breaking nozzle 4 to take a minimum value, dP / dr> 0 in all regions of the end face P1 on the downstream side of the vortex breaking nozzle 4 Need to be. Further, in the state indicated by S1, in order for the pressure at the outlet of the vortex breaking nozzle 4 to take the maximum value, it is necessary to satisfy dP / dr <0 at the downstream end face P1 of the vortex breaking nozzle 4. .

として式（３４）を用い、さらにｈ（ｒ）＝const.＝ｈ₀ の場合について議論する。
式（３５）から圧力勾配が０となるｒ＝ｒ_crを求めると

となる。また、

である。このとき圧力勾配は

である。 Below, for simplicity

The case where h (r) = const. = H ₀ is further discussed using equation (34).
When r = r _cr where the pressure gradient becomes 0 is obtained from the equation (35),

It becomes. Also,

It is. At this time, the pressure gradient is

It is.

流体が水の場合には条件式（４０）の境界値ｈ₀ はＤ_e ／２に比べて極めて小さいため、Ｓ２の条件は式（２８）、（２９）から

となる（本実験範囲（Ｄ〜５Ｄ_e ）では式（１８）がおよその目安となったが、Ｄの値如何によって式（４１）に基づきｈ₀ を決定すれば良い）。また、Ｓ１に関してはｈ₀ が小さいほど渦崩壊用ノズル４の出口の圧力は大きくなる。一方でｈ₀ が小さいとポンプに負荷が掛かるため、式（３８）を満たしポンプの効率が小さくならない範囲でｈ₀ を決定すべきである。式（３９）中のｒ_crをＤ_e ｒ_n ／２とおくと、ｈ₀ は近似的に

で与えられる。式（４２）でｒ_n ＝１と置いたｈ₀ の場合には渦崩壊用ノズル４の下流側の端面Ｐ１のすべての領域で圧力勾配は負となり、渦崩壊用ノズル４の中心の圧力は必ず増加する。この場合、前記の実験ＩＩの値を代入するとｈ₀ ＝０．１２ｍｍとなる。このような小さなｈ₀ に対しては式（３１）から抵抗が支配的となり式（３４）は適用できず、近似式

の方が妥当である。この場合には式（４２）の右辺第２項を０と置くことができる。最終的にＳ１の状態を実現するためには上記の式（１７）が必要である。ここで、ｒ_n ＝１＋（Ｄ／Ｄ_e −１）／２は渦崩壊用ノズル４の下流側の端面Ｐ１と圧力遮断用ノズル２１の上流側の端面Ｐ２とで囲まれた狭窄部の放射方向半分の距離まで圧力が減少し後半で増加するとした場合である。特に、Ｓ１に示す状態の場合にも、渦崩壊用ノズル４の出口（ｒ＜Ｄ_e ／２）の旋回流は微細気泡の生成に重要であることを実験的に確かめた。 In the state of S1, the pressure at the outlet of the vortex breaking nozzle 4 is increased by the pressure blocking nozzle 21 and needs to be decreased in the state of S2, and it is determined that the following equation is satisfied.

When the fluid is water, the boundary value h ₀ of the conditional expression (40) is extremely small compared to _De / 2, and therefore the condition of S2 is determined from the expressions (28) and (29).

(In the present experimental range (D to 5D _e ), equation (18) is an approximate guide, but h ₀ may be determined based on equation (41) depending on the value of D). The pressure at the outlet of the vortex breakdown nozzle 4 more h ₀ is small becomes large with respect to S1. On the other hand, if h ₀ is small, a load is applied to the pump. Therefore, h ₀ should be determined within a range that satisfies equation (38) and does not reduce the efficiency of the pump. When placing the r _cr in formula (39) and _{D e r n / 2, h} 0 is approximately

Given in. In the case of h ₀ where r _n = 1 is set in the equation (42), the pressure gradient is negative in all regions of the downstream end face P1 of the vortex breaking nozzle 4, and the pressure at the center of the vortex breaking nozzle 4 is Will definitely increase. In this case, if the value of Experiment II is substituted, h ₀ = 0.12 mm. For such a small h ₀ , the resistance is dominant from Equation (31), and Equation (34) cannot be applied.

Is more reasonable. In this case, the second term on the right side of Equation (42) can be set to 0. In order to finally realize the state of S1, the above equation (17) is necessary. Here, r _n = 1 + (D / D _e −1) / 2 is the radiation of the constricted portion surrounded by the downstream end face P1 of the vortex breaking nozzle 4 and the upstream end face P2 of the pressure blocking nozzle 21. This is the case where the pressure decreases to half the direction and increases in the second half. In particular, even in the state shown in S1, it was experimentally confirmed that the swirling flow at the outlet of the vortex breaking nozzle 4 (r <D _e / 2) is important for the generation of fine bubbles.

が付加される。したがって、Ｓ２の状態においては前記の流体層が渦崩壊用ノズル４の下流側の端面Ｐ１から剥離しない範囲（式（２９））でｄｈ／ｄｒ（正）を大きくすることで渦崩壊用ノズル４の出口の圧力をより小さくすることができる。Ｓ１においてはｄｈ／ｄｒ≦０が望まれる。 For an arbitrary interval h (r), the pressure on the nozzle front surface can be estimated by integrating the equations (31) and (35) in the positive direction from r = D _e / 2 to r. When h (r) changes in the r direction, the pressure gradient dP / dr is changed from the first term on the right side of Equation (35).

Is added. Therefore, in the state of S2, the vortex breakdown nozzle 4 is increased by increasing dh / dr (positive) in a range (formula (29)) in which the fluid layer does not peel from the downstream end face P1 of the vortex breakdown nozzle 4. The pressure at the outlet can be made smaller. In S1, dh / dr ≦ 0 is desired.

より大きい場合である（前記の実験ＩＩの値を代入するとｋ_S 〜０．００２ｍｍ程度である）。一般に、式（４５）はｈに比べて十分小さいため、Ｓ１でｈが極端に小さくなる場合には粗度を付けて圧力を高くすることが有効である。粗面の場合の抵抗係数式（３３）を用いて、式（４３）の近似の下で式（１７）と同様な関係式を導くと

が得られる。間隙２２のすべての領域で圧力がｒ方向に増加するとすると（ｒ_n ＝１）、粗度に対する間隔ｈ（ｒ）は図５２で与えられる。特に研磨しない材料で渦崩壊用ノズル４を作った場合にはその表面は粗面であり、図５２から間隙２２の間隔ｈ（ｒ）はおよそ噴出口Ｑの半径の１／３０から１／２０であることが分かる。
以上の主な結論をまとめると、
圧力遮断用ノズル２１は、渦崩壊用ノズル４と圧力遮断用ノズル２１との間隔ｔを変化させることで、下記の二つの異なるタイプの気泡生成を行うことができる。
減圧後の加圧によるマイクロバブル生成

加圧後の減圧によるマイクロバブル生成

ただし、上記の条件は間隙２２のすべての領域で圧力がｒ方向に増加する場合である。 As described above, the case where the surface of the vortex breaking nozzle 4 is smooth is discussed.
S1: Since the pressure at the outlet of the vortex breaking nozzle 4 is preferably high, the surface of the vortex breaking nozzle 4 is preferably rough so that the resistance is increased.
S2: Since it is better that the pressure at the outlet of the vortex breaking nozzle 4 is lower, the surface of the vortex breaking nozzle 4 should be smooth so that the resistance is reduced.
Here, the rough surface means that the height k _s of the surface unevenness is

This is the case when the value is larger (substituting the value of Experiment II above, it is about k _{S to} about 0.002 mm). In general, since equation (45) is sufficiently smaller than h, it is effective to increase the pressure by adding roughness when h is extremely small in S1. Using the resistance coefficient equation (33) in the case of a rough surface, a relational expression similar to equation (17) is derived under approximation of equation (43).

Is obtained. If the pressure increases in the r direction in all regions of the gap 22 (r _n = 1), the spacing h (r) for the roughness is given in FIG. In particular, when the vortex breaking nozzle 4 is made of a material that is not polished, the surface thereof is rough, and the interval h (r) of the gap 22 is about 1/30 to 1/20 of the radius of the jet port Q from FIG. It turns out that it is.
To summarize the main conclusions,
The pressure blocking nozzle 21 can generate the following two different types of bubbles by changing the interval t between the vortex breaking nozzle 4 and the pressure blocking nozzle 21.
Microbubble generation by pressurization after decompression

Microbubble generation by depressurization after pressurization

However, the above condition is when the pressure increases in the r direction in all regions of the gap 22.

Although one embodiment of the present invention has been specifically described above, the present invention is not limited to the above-described embodiment and examples, and various modifications based on the technical idea of the present invention are possible. .
For example, the numerical values, shapes, structures, arrangements, and the like given in the above-described embodiments are merely examples, and different numerical values, shapes, structures, arrangements, and the like may be used as necessary.

It is a perspective view which shows the main body of the swirl | vortex type | mold microbubble generator by a 1st example. It is a perspective view which shows the blade body of the turbine blade type nozzle of the swirl | vortex type | mold microbubble generator by a 1st example. It is a front view which shows the blade | wing body of the turbine blade type nozzle of the swirl | vortex type | mold microbubble generator by a 1st example. It is a longitudinal cross-sectional view which shows the blade body of the turbine blade type nozzle of the swirl | vortex type | mold microbubble generator by a 1st example. It is a basic diagram which shows the shape of one blade | wing of the blade body of the turbine blade type nozzle of the swirl | vortex type | mold microbubble generator by a 1st example. It is a longitudinal cross-sectional view which shows the nozzle for vortex breakdown of the swirl | vortex type | mold microbubble generator by a 1st example. It is a longitudinal cross-sectional view which shows the air supply apparatus of the swirl | vortex type | mold microbubble generator by a 1st example. It is a basic diagram for demonstrating the circulation number in the contraction part of the nozzle for vortex collapse of the swirl | vortex type | mold microbubble generator by a 1st example. It is a basic diagram for demonstrating the critical nozzle radius of the vortex breakdown nozzle of the swirl | vortex type | mold microbubble generator by a 1st example. It is a basic diagram which shows the vortex collapse which arises in the nozzle for vortex collapse of the swirl | vortex type | mold microbubble generator by a 1st example. It is a basic diagram for demonstrating a Hinze scale. It is a basic diagram which shows the air supply amount when microbubbles are atomized to a Hinze scale when the circulation number is 2 in the swirling flow type microbubble generator according to the first example. It is a basic diagram which shows the air supply amount when microbubbles are atomized to a Hinze scale when the number of circulations is 3 in the swirling flow type microbubble generator according to the first example. It is a basic diagram which shows the air supply amount when microbubbles are atomized to a Hinze scale when the circulation number is 4 in the swirling flow type microbubble generator according to the first example. FIG. 6 is a schematic diagram showing a ratio of an air supply amount and a liquid flow rate when microbubbles are atomized to a Hinze scale when the circulation number is 2 in the swirling flow type microbubble generator according to the first example. FIG. 6 is a schematic diagram showing a ratio between an air supply amount and a liquid flow rate when microbubbles are atomized to a Hinze scale when the circulation number is 3 in the swirling flow type microbubble generator according to the first example. FIG. 6 is a schematic diagram showing a ratio of an air supply amount and a liquid flow rate when microbubbles are atomized to a Hinze scale when the circulation number is 4 in the swirling flow type microbubble generator according to the first example. It is a table | surface for demonstrating the Example of the turbine blade type nozzle of the swirl | vortex type | mold microbubble generator by a 1st example. Outline diagram for explaining examples of shape of turbine blade type nozzle, shape of vortex breaking nozzle and distance from turbine blade type nozzle to vortex breaking nozzle of swirling flow type microbubble generator according to the first example It is. It is a longitudinal cross-sectional view which shows the vortex breaking nozzle of the swirl | vortex type | mold microbubble generator by a 2nd example. It is a basic diagram which compared the generation | occurrence | production condition of the microbubble in the swirl type microbubble generator by a 2nd example with another example. It is a basic diagram which shows the mode of two types of vortex collapse in the swirl | vortex type | mold microbubble generator by a 2nd example. It is a longitudinal cross-sectional view which shows the swirl | vortex type | mold microbubble generator by a 3rd example. It is a longitudinal cross-sectional view which shows the swirl | vortex type | mold microbubble generator by a 4th example. It is a longitudinal cross-sectional view which shows the main body of the swirl | vortex type | mold microbubble generator by a 5th example. It is a basic diagram which shows the spectrum of the sound wave measured in order to confirm the generation | occurrence | production condition of the microbubble in the swirl type microbubble generator by the 6th example. It is a basic diagram which shows the spectrum of the image measured in order to confirm the generation | occurrence | production state of the microbubble in the swirl type microbubble generator by the 6th example. It is the longitudinal cross-sectional view which shows the vortex breaking nozzle of the swirl | vortex type | mold microbubble generator by a 7th example, and the enlarged view of the edge of the exit of this vortex breaking nozzle. It is a basic diagram which shows the supercritical vortex breakdown which arises in the nozzle for vortex breakdown of the swirl | vortex type | mold microbubble generator by a 7th example. It is a basic diagram which shows the subcritical vortex breakdown which arises in the nozzle for vortex breakdown of the swirl | vortex type | mold microbubble generator by a 7th example. It is a longitudinal cross-sectional view which shows the example of the shape of the nozzle for vortex collapse of the swirl | vortex type | mold microbubble generator by a 7th example. It is sectional drawing which shows the principal part of the swirl type microbubble generator by one Embodiment of this invention. It is sectional drawing which shows the principal part of the swirl type microbubble generator by one Embodiment of this invention. It is a basic diagram for demonstrating the characteristic of the swirl type microbubble generator by one Embodiment of this invention. It is sectional drawing which shows the principal part of the swirl type microbubble generator by one Embodiment of this invention. It is sectional drawing which shows the principal part of the swirl type microbubble generator by one Embodiment of this invention. It is a basic diagram for demonstrating the characteristic of the swirl type microbubble generator by one Embodiment of this invention. It is a basic diagram for demonstrating the characteristic of the swirl type microbubble generator by one Embodiment of this invention. It is a basic diagram for demonstrating the characteristic of the swirl type microbubble generator by one Embodiment of this invention. It is a basic diagram for demonstrating the characteristic of the swirl type microbubble generator by one Embodiment of this invention. It is a basic diagram for demonstrating the characteristic of the swirl type microbubble generator by one Embodiment of this invention. It is a basic diagram for demonstrating the characteristic of the swirl type microbubble generator by one Embodiment of this invention. It is a basic diagram for demonstrating the characteristic of the swirl type microbubble generator by one Embodiment of this invention. It is a basic diagram for demonstrating the characteristic of the swirl type microbubble generator by one Embodiment of this invention. It is sectional drawing which shows the principal part of the swirl type microbubble generator by one Embodiment of this invention. It is sectional drawing which shows the high concentration microbubble generator using the swirl | flow type microbubble generator by one Embodiment of this invention. It is sectional drawing which shows the principal part of the swirl type microbubble generator by one Embodiment of this invention. It is sectional drawing which shows the principal part of the swirl type microbubble generator by one Embodiment of this invention. It is sectional drawing which shows the principal part of the swirl type microbubble generator by one Embodiment of this invention. It is sectional drawing which shows the principal part of the swirl type microbubble generator by one Embodiment of this invention. It is sectional drawing which shows the principal part of the swirl type microbubble generator by one Embodiment of this invention. It is a basic diagram for demonstrating the characteristic of the swirl type microbubble generator by one Embodiment of this invention.

Explanation of symbols

  2 ... pipe, 2a ... vortex section, 3 ... turbine blade type nozzle, 3a ... main body, 3b ... blade, 3e ... air supply hole, 3f ... injection hole, 4 ... vortex breakup nozzle, 4a ... constriction section, 4b ... vortex Collapse part, 4h ... Taper part, 4k ... Edge, 6 ... Liquid, 6a ... Liquid flow, 6b ... Air column, 6c ... Swirl flow, 6d ... Microbubble, 21 ... Pressure blocking nozzle

Claims (6)

A second nozzle for pressure blocking provided on the end face on the downstream side of the first nozzle having a micro-bubble jet port, which is opposed to the first nozzle and provided coaxially;
The first nozzle has a contraction part and a vortex breakdown part sequentially from the upstream side to the downstream side, and supplies the swirl flow of the liquid into which gas is introduced at the center to the contraction part. It is a vortex breakdown nozzle that generates microbubbles from the collapsed part,
A gap is formed between the downstream end surface of the first nozzle and the upstream end surface of the second nozzle,
The portion of the second nozzle that faces the jet outlet is configured to block the low-pressure portion at the center of the swirling flow coming out of the jet outlet from the downstream side of the second nozzle,
The portion of the second nozzle that faces the spout does not penetrate the spout ,
The microbubbles ejected from the ejection port are configured to go outside through the gap,
When the apex angle of the downstream end face of the first nozzle is θ _VB and the apex angle of the upstream end face of the second nozzle is θ _SU , Δθ≡θ _VB −θ _SU = 10 ° to 20 ° swirling flow type micro-bubble generating device, characterized in that it. The first nozzle and the second nozzle are housed inside a tube, and the microbubbles ejected from the ejection port pass through the gap, and further on the outer peripheral surface of the tube and the second nozzle. The swirl type microbubble according to claim 1, wherein the microbubble is configured to be discharged to the outside through a space between a plurality of grooves provided in parallel to the central axis of the second nozzle. Generator. The first nozzle and the second nozzle are accommodated in a pipe, and the microbubbles ejected from the ejection port pass through the gap, and further the second nozzle inside the second nozzle. 2. The swivel according to claim 1, wherein the swirl is configured to be discharged to the outside through a plurality of holes provided in parallel to the central axis of the second nozzle at a portion close to the outer peripheral surface of the second nozzle. Flow type microbubble generator. The first nozzle and the second nozzle are housed inside a tube, the second nozzle has a shape that swells downstream, and the second nozzle has the above-mentioned inside There are provided a plurality of holes that communicate between the gap in the portion adjacent to the inner wall of the tube and the downstream end surface of the second nozzle and that merge with each other at the downstream end surface of the second nozzle. The microbubbles ejected from the ejection port pass through the gap, and are further discharged to the outside through the plurality of holes of the second nozzle. The swirling flow type microbubble generator as described. The swirling flow type microbubble generator according to any one of claims 1 to 4, further comprising a wing-shaped third nozzle for swirling flow generation on the upstream side of the first nozzle. A swirl flow is generated by supplying a liquid to the inlet on the upstream side of the third nozzle, a gas is introduced into the center of the swirl flow, and the swirl flow with the gas introduced into the center is converted into the first flow. 6. The swirling flow type microbubble generating device according to claim 5, wherein microbubbles are generated from the vortex breakdown portion by supplying the contracted flow portion of the nozzle.

Images