JP2022040084A - Stirring method, stirring device, and stirring container - Google Patents

Abstract

To realize very easy stirring which does not use stirring blades in a stirring method, a stirring device, and a stirring container.SOLUTION: A stirring method includes: preparing a stirring container 10, having an inner surface having a closed rotary body shape, and a rotation mechanism 20 for rotating the stirring container 10; placing a first fluid to be stirred and a second fluid, which forms a boundary without being mixed with the first fluid, into the stirring container 10; and rotating the stirring container 10 by the rotation mechanism 20 to generate twisting flow in the first fluid and thereby stir the first fluid.SELECTED DRAWING: Figure 1

Description

The present invention relates to a stirring method, a stirring device, and a stirring container.

A stirring device that stirs a fluid by rotating a stirring blade in a tank is known. However, in such a stirrer, problems such as damage and contamination of the mixture by the stirrer blade and cleaning of the stirrer blade arise.

Patent Document 1 discloses a stirring device that does not use a stirring blade to solve the above problem. This stirring device stirs a fluid by rotating a bottomed cylinder having a central axis arranged at an angle from the vertical direction around the central axis.

International Publication No. 2017/149034

However, in the stirring device of Patent Document 1, it is necessary to incline the central axis to install the bottomed cylinder, and the structure is complicated. Further, the stirring device of Patent Document 1 does not have a lid (top surface) and is open upward. Therefore, it is necessary to stir the fluid by shear forces only on the bottom and sides. Also, there is no mention of torsional flow (details below) that self-sustainably generate turbulence.

An object of the present invention is to realize extremely simple stirring without using a stirring blade in a stirring method, a stirring device, and a stirring container.

In the first aspect of the present invention, a stirring container having a closed rotating body-shaped inner surface and a rotating mechanism for rotating the stirring container are prepared, and the first fluid to be stirred is not mixed with the first fluid. It includes agitating the first fluid by putting a second fluid forming a boundary into the stirring container, rotating the stirring container by the rotation mechanism, and generating a twisting flow in the first fluid. , Provide a stirring method.

According to this method, it is possible to provide an extremely simple stirring method that does not use a stirring blade. Characteristically, the stirring produces a flow called a torsional flow in the first fluid. The torsional flow is a flow caused by at least one spiral vortex. The inventors of the present application have experimentally confirmed the occurrence of the twisted flow. The principle of this twisting flow generation is scientifically non-trivial, but it is known that the generation of this twisting flow causes turbulence to be generated in a self-sustaining manner. Therefore, a turbulent flow is generated in the first fluid, and the first fluid can be efficiently agitated. The above-mentioned stirring does not mix the first fluid and the second fluid, but stirs the first fluid alone. Therefore, it seems that the second fluid is unnecessary at first glance, but when only the first fluid is filled in the stirring container, the first fluid rotates together with the stirring container. That is, in this case, a so-called rigid rotating flow is generated, and no turbulent flow is generated. Therefore, a boundary between the first fluid and the second fluid is required for the generation of turbulence.

The inner surface of the stirring container has a central axis at a portion in contact with the first fluid, and has a shape of a rotating body formed by rotating a convex curve in a direction away from the central axis once around the central axis. You may have.

According to this method, the inner surface shape of the stirring container can be specifically defined. Further, since the shape of the inner surface of the stirring container is symmetrical around the central axis at the portion in contact with the first fluid, the shape is simplified. Here, the "curvature convex in the direction away from the central axis" may be a convex shape in the direction away from the central axis as a whole, may include a concave portion toward the central axis, or may be variable. It may include curved points (change points of the radius of curvature) and angles (parts where the radius of curvature is infinite).

The central axis may coincide with the rotation axis of the rotation of the stirring container by the rotation mechanism.

According to this method, the height position (depth position) of the first fluid does not change in the stirring container. Specifically, since the central axis and the rotation axis coincide with each other, the position of the lower point on the inner surface of the stirring container does not change with rotation. Therefore, stable stirring can be realized without the first fluid swinging in a wavy manner with the rotation of the stirring container.

The tilt angle of the rotation axis of the stirring container by the rotation mechanism with respect to the horizontal direction may be within 30 °. Further, the rotation axis may extend in the horizontal direction.

According to these methods, by limiting the tilt angle of the stirring container, stable stirring can be realized without the boundary changing significantly from the horizontal position.

The inner surface of the stirring container may be spherical. Further, the inner surface of the stirring container may be an asymmetric sphere in which two partial spheres having different radii are joined. Further, the inner surface of the stirring container may be cylindrical.

According to these methods, it is possible to provide a stirring device having a high versatility and an extremely simple configuration.

The first fluid may contain at least one liquid and the second fluid may contain at least one gas.

According to this method, the boundary between the first fluid and the second fluid is easily formed, and preparation is easy. Further, the first fluid may be, for example, liquid water and oil, and the second fluid may be, for example, gaseous air. As a result, an emulsion can be realized by stirring water and oil. Alternatively, the first fluid may be a slurry consisting of a liquid such as water and a powder.

The filling rate of the first fluid to the stirring container may be 20% or more and 90% or less.

According to this method, the first fluid can be agitated more reliably. The inventors of the present application have experimentally confirmed the effectiveness of stirring at a filling rate of 20 to 90%. Specifically, the filling factor of the first fluid may not be 0% or 100%. Assuming that the filling rate of the first fluid is 100%, the first fluid rotates together with the stirring container. Therefore, no turbulence is generated in the first fluid and the first fluid is not agitated.

The rotation of the stirring container may be at a constant speed.

According to this method, the present invention can be realized with a rotation mechanism having a simple structure. Usually, in a stirring device, stirring is promoted by changing and controlling the direction and speed of rotation. However, the present invention does not require such change control. In other words, even at a constant speed of rotation, the first fluid can be agitated because the turbulent flow is self-sustainably generated by the generation of the torsional flow.

A second aspect of the present invention is a stirring container having a closed rotating body-shaped inner surface that houses a first fluid to be stirred and a second fluid that forms a boundary without being mixed with the first fluid. Provided is a stirring device including a rotating mechanism for stirring the first fluid by rotating the stirring container and generating a twisting flow in the first fluid.

The inner surface of the stirring container has a central axis at a portion in contact with the first fluid, and has a shape of a rotating body formed by rotating a convex curve in a direction away from the central axis once around the central axis. You may have.

The central axis may coincide with the rotation axis of the rotation of the stirring container by the rotation mechanism.

The tilt angle of the rotation axis of the stirring container by the rotation mechanism with respect to the horizontal direction may be within 30 °. Further, the rotation axis may extend in the horizontal direction.

The inner surface of the stirring container may be spherical. Further, the inner surface of the stirring container may be an asymmetric sphere in which two partial spheres having different radii are joined. Further, the inner surface of the stirring container may be cylindrical.

The first fluid may contain at least one liquid and the second fluid may contain at least one gas.

The filling rate of the first fluid to the stirring container may be 20% or more and 90% or less.

The rotation of the stirring container may be at a constant speed.

A third aspect of the present invention has a closed rotating body-like inner surface that houses a first fluid to be agitated and a second fluid that forms a boundary without being mixed with the first fluid, and is rotated. Thereby, a stirring container for generating a twisting flow in the first fluid and stirring the first fluid is provided.

According to the present invention, the present invention can realize extremely simple stirring without using a stirring blade by confirming the torsional flow in the stirring method, the stirring device, and the stirring container.

The schematic block diagram of the stirring apparatus which concerns on 1st Embodiment of this invention. Schematic explanatory view showing a twist flow. Sectional drawing showing the result of a numerical simulation. The perspective view which shows the experimental apparatus. Perspective view of the stirring container part of the experimental device. A photograph showing the experimental results with a filling rate of 20%. A photograph showing the experimental results with a filling rate of 50%. A photograph showing the experimental results with a filling rate of 70%. A photograph showing the experimental results with a filling rate of 80%. A photograph showing the experimental results with a filling rate of 90%. The front view which shows the modification of the rotation mechanism. Explanatory drawing which shows the shape of the modification of a stirring container. Schematic diagram of a modified example of the stirrer. The schematic block diagram of the stirring apparatus which concerns on 2nd Embodiment. Explanatory drawing which shows the shape of a stirring container. Sectional drawing showing the result of a numerical simulation. A photograph showing the experimental results. The schematic block diagram of the stirring apparatus which concerns on 3rd Embodiment. Sectional drawing showing the result of a numerical simulation. A photograph showing the experimental results.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

(First Embodiment)
FIG. 1 is a schematic configuration diagram of the stirring device 1 according to the first embodiment. In FIG. 1, the X direction indicates the direction in which the rotation axis RA extends in the horizontal plane, the Y direction indicates the vertical direction, and the Z direction indicates the direction orthogonal to the X direction in the horizontal plane.

First, the configuration of the stirring device 1 will be described.

The stirring device 1 has a stirring container 10 and a rotating mechanism 20.

The stirring container 10 is a container having a closed rotating body-shaped inner surface 10a and accommodating a fluid to be stirred. The stirring container 10 of the present embodiment is a spherical shell-shaped container having a uniform thickness. Therefore, the inner surface 10a of the stirring container 10 is spherical. The stirring container 10 having a spherical inner surface 10a has a high versatility and an extremely simple structure, and unlike a cylindrical stirring container or the like, it has no directivity and can be installed in any direction. However, as will be described in detail later, the shape of the inner surface 10a of the stirring container 10 is not limited to a spherical shape and may vary. Further, the size and material of the stirring container 10 can be arbitrarily set.

The rotation mechanism 20 is mechanically connected to the stirring container 10 and rotates the stirring container 10 around the rotation axis RA. The rotation mechanism 20 of the present embodiment is composed of a rotation shaft member 21 extending in the direction of the rotation shaft RA and supporting the stirring container 10 and a motor 22 for rotating the rotation shaft member 21 around the rotation shaft RA. The rotation axis RA passes through the spherical center point P of the stirring vessel 10 and extends in the horizontal direction (specifically, the X direction).

Next, a stirring method using the stirring device 1 will be described.

After preparing the stirring device 1, the first fluid to be stirred and the second fluid different from the first fluid are put into the stirring container 10. The first fluid and the second fluid may be selected to form a boundary without being mixed due to a difference in properties such as density when placed in the stirring container 10. Further, the first fluid may contain at least one kind of liquid, and the second fluid may contain at least one kind of gas. For example, the first fluid may be a liquid and the second fluid may be a gas. Alternatively, both the first fluid and the second fluid may be liquids, and the first fluid may have a higher density than the second fluid.

In this embodiment, the first fluid is water and the second fluid is air. Further, the filling rate of the first fluid to the stirring container 10 is 50%, and the filling rate of the second fluid to the stirring container 10 is 50%. The filling factor can be changed in various ways, but the details will be described later. In the example of FIG. 1, the lower hemisphere shown by the broken line indicates the first fluid (water), and the upper hemisphere indicates the second fluid (air).

After filling the stirring container 10 with the first fluid and the second fluid, the stirring container 10 is rotated around the rotation axis RA by the rotation mechanism 20. The rotation speed may be constant or variable. In this embodiment, the stirring container 10 is rotated at a constant speed.

Preferably, the Reynolds number is set to be several hundreds or more when the first fluid is stirred. More preferably, the Reynolds number is set to 1000 or more when the first fluid is stirred.

By the stirring device 1 and the stirring method, the first fluid is stirred while the boundary between the first fluid and the second fluid is maintained. The stirring of the present embodiment does not mix the first fluid and the second fluid, but stirs the first fluid. This agitation is due to the formation of a flow called a torsional flow in the first fluid. The torsional flow is a flow caused by a pair of spiral vortices. As will be described later, the inventors of the present application have experimentally confirmed the occurrence of the torsional flow. The principle of this torsional flow generation is scientifically non-trivial, but it is known that the generation of this torsional flow causes turbulent flow to be generated in a self-sustaining manner. Therefore, the turbulent flow is generated in the first fluid, so that the first fluid can be efficiently agitated.

FIG. 2 is a schematic explanatory view showing a twist flow. In FIG. 2, only the first fluid of FIG. 1 is shown for clarity.

In the present embodiment, the torsional flow is a flow caused by a pair of spiral vortices each having a swirling axis SR in the YZ plane, and a shear flow is generated between the pair of spiral vortices (hatched area A). Specifically, each swivel axis SR does not coincide with the rotary axis RA of the stirring vessel 10, and the size (radius) of each of the pair of spiral vortices is about the radius of the stirring vessel 10. The flow velocity is about the rotation speed of the inner surface 10a of the stirring container 10. This kinky flow creates turbulence in a self-sustaining manner.

In this embodiment, the results of the above-mentioned stirring, especially the generation of twisted flow, were confirmed from both numerical simulations and experiments by changing various parameters.

First, the numerical simulation will be described.

FIG. 3 is an explanatory diagram showing the results of numerical simulation. Note that FIG. 3 shows an XY cross section passing through the center point P (see FIG. 1) of the stirring vessel 10.

In the numerical simulation, the stirring container 10 having a spherical inner surface 10a was filled with the first fluid and the second fluid at a filling rate of 50% each, and the stirring container 10 was rotated by a rotation axis passing through the center of the sphere in the horizontal plane. As the first fluid, water was assumed, and the viscosity was set to 0.001 [Pa · S], the density was 1000 [kg / m ³ ], and the surface tension was 0.072 [N / m]. Air was assumed as the second fluid, and it was simply set to 1/10 of the physical property value of the first fluid. Further, the diameter of the inner surface 10a of the stirring container 10 was set to 180 mm, and the rotation speed was set to 6 rpm.

As a result of the numerical simulation, a pair of spiral vortices that spirally swirl around the pair of swirl axes SR were generated. In addition, the directions of rotation of the pair of spiral vortices were opposite to each other (in FIG. 3, the vortex on the left side is clockwise and the vortex on the right side is counterclockwise). The generation of shear flow was confirmed between the pair of spiral vortices. Therefore, in the numerical simulation, the generation of torsional flow was confirmed, and the generation of self-sustaining turbulence was confirmed.

Next, the experiment will be described.

FIG. 4 is a perspective view showing the experimental device 2. FIG. 5 is a perspective view of the stirring container 10 portion of the experimental device 2.

In the experimental device 2, the stirring container 10 and the rotating mechanism 20 are arranged on the table 3. Then, the state of stirring was observed from the rotation axis direction (X direction) by the camera 4.

The rotation mechanism 20 includes a rotation shaft member 21 (see FIG. 5) and a motor 22 (see FIG. 4) that rotates the rotation shaft member 21. The rotary shaft member 21 is mechanically connected to the stirring container 10. The rotary shaft member 21 extends in the horizontal direction (specifically, the X direction). When the rotary shaft member 21 is extended, it passes through the center point P (see FIG. 1) of the stirring container 10.

The stirring container 10 has a substantially cylindrical outer shape and a spherical inner shape having a diameter of 180 mm. The stirring container 10 can be separated into the substrate 11 and the lid 12 in the X direction (rotational axis direction). The inner surface 10a of both the substrate 11 and the lid 12 is a hemisphere. Further, the substrate 11 and the lid 12 are made of transparent acrylic so that the inside can be easily seen. The substrate 11 and the lid 12 have flange portions 11a and 12a, respectively. The flange portions 11a and 12a are in surface contact with each other on the YZ plane and are screwed together. The substrate 11 is mechanically connected to the rotary shaft member 21, and the lid 12 is attached to the vertical wall 5 via the bearing 13. The vertical wall 5 is erected on the table 3, and a hole portion 14 having a diameter substantially the same as that of the bearing is provided in the center thereof. Further, the camera 4 is installed so as to look inside the stirring container 10 from the hole 14.

At the time of observation, water and air were added to the stirring container 10 at different filling rates as follows, and mica particles were further added as a visualization agent. Further, the laser beam LB was diffused and irradiated from the laser source 7 through the rod lens 6 attached above the stirring container 10, and the flow was visualized. The temperature of the water to be stirred was set to 22 ° C., and the rotation speed of the stirring container 10 was set to 48 rpm. Moreover, the Reynolds number was set to be about 40,000.

FIGS. 6 to 10 are photographs showing the experimental results of water filling rates of 20%, 30%, 50%, 70%, 80%, and 90%, respectively. As shown in FIGS. 6 to 10, it was confirmed that the turbulent flow was maintained at any filling factor. Based on these results, the filling factor of the first fluid with respect to the stirring container 10 may be set to 20% or more and 90% or less.

(Modification example of rotation mechanism)
In the above embodiment, the rotation mechanism 20 exemplifies a configuration in which the stirring container 10 is supported by the rotation shaft member 21, but the configuration of the rotation mechanism 20 is not limited to this.

FIG. 11 is a front view showing a modified example of the rotation mechanism 20. As the rotation mechanism 20, a configuration may be adopted in which the stirring container 10 is supported from below by a rotating body 23 such as a columnar roller. In the example of FIG. 11, the rotation mechanism 20 is composed of two rotating bodies 23, but the number and size of the rotating bodies 23 are not particularly limited.

As described above, various configurations of the rotation mechanism 20 can be considered, and any configuration capable of rotating the stirring container 10 in a predetermined rotation direction can be adopted.

(Modification example of stirring container)
In the above embodiment, the shape of the stirring container 10 is exemplified by the spherical shell shape, but the shape of the stirring container 10 is not limited to the spherical shell shape.

For example, as shown in Experimental Device 2 (see FIGS. 4 and 5), if the inner surface 10a of the stirring container 10 is spherical, any shape can be adopted as the outer shape. Furthermore, the shape of the inner surface 10a of the stirring container 10 may be other than spherical. Specifically, the stirring container 10 may have a closed rotating body-like inner surface. This closed rotating body-shaped inner surface has a central axis CA at a portion in contact with the first fluid, and is a rotating body formed by rotating a convex curve in a direction away from the central axis CA once around the central axis CA. It may have the shape of (see FIG. 12 described later). Here, the "curvature convex in the direction away from the central axis CA" may be a convex shape in the direction away from the central axis CA as a whole, and may include a concave portion toward the central axis. It may also include inflection points (change points of the radius of curvature) and angles (parts where the radius of curvature is infinite). By defining in this way, the inner surface 10a of the stirring container 10 can be easily defined. Further, since the shape of the inner surface 10a of the stirring container 10 is symmetrical around the central axis CA at the portion in contact with the first fluid, the shape is simplified.

Further, the central axis CA may coincide with the rotation axis RA. In this case, the height position (depth position) of the first fluid in the stirring container 10 does not change even if the stirring container 10 rotates. Specifically, since the central axis CA and the rotation axis RA coincide with each other, the position of the lower point of the inner surface 10a of the stirring container 10 does not change with rotation. Therefore, stable stirring can be realized without the first fluid swinging in a wavy manner with the rotation of the stirring container 10.

With reference to FIG. 12, as another example of the inner surface shape of the stirring vessel 10, a curved surface formed by rotating a convex quadratic function curve C once around the rotation axis RA from the rotation axis RA corresponding to the central axis CA is adopted. You may. With reference to FIG. 13, the curved surface thus formed has a substantially rugby ball shape (see the inner surface 10a). Although the quadratic function curve C is illustrated in FIGS. 12 and 13, the curve is not limited to the quadratic function and can be adopted in various ways. Preferably, the curve has no inflection. As described above, various shapes of the inner surface of the stirring container 10 can be considered. The inner surface has a shape required in a portion that comes into contact with the first fluid, and any inner surface shape may be adopted in the portion that does not come into contact with the first fluid.

(Second Embodiment)
In the stirring device 1 of the second embodiment shown in FIG. 14, the shape of the stirring container 10 is different from that of the first embodiment. Except for the part related to this, it is substantially the same as the first embodiment. Therefore, the description of the portion shown in the first embodiment may be omitted.

The inner surface 10a of the stirring container 10 of the present embodiment is an asymmetric spherical shape. Specifically, the inner surface 10a is an asymmetric sphere formed by joining two partial spheres with different radii.

FIG. 15 is an explanatory diagram showing the shape of the stirring container 10 in the present embodiment.

In the present embodiment, the inner surface 10a is a curved surface formed by rotating two arcs C1 and C2 having center points P1 and P2 once around the rotation axis RA from the rotation axis RA corresponding to the center axis CA. In the illustrated example, the arc C1 is slightly larger than a quarter of the circumference and the arc C2 is slightly smaller than a quarter of the circumference.

Also in this embodiment, the results of the above-mentioned stirring, especially the generation of twisted flow, were confirmed from both numerical simulations and experiments.

First, the numerical simulation will be described.

FIG. 16 is an explanatory diagram showing the results of numerical simulation. Note that FIG. 16 shows an XY cross section passing through the center points P1 and P2 (see FIGS. 14 and 15). Further, in the present embodiment, since the central axis CA and the rotary axis RA are aligned with each other in the extending direction of the rotary shaft member 21, the central axis CA and the rotary shaft RA are not shown.

In the numerical simulation, the radius of the arc C1 was set to 42 mm, the radius of the arc C2 was set to 40 mm, and the distance between the center points P1 and P2 was set to 9 mm for the shape of the inner surface 10a. Then, the stirring container 10 was filled with the first fluid and the second fluid at a filling rate of 50% each, and the stirring container 10 was rotated by a rotation axis passing through the center points P1 and P2 in the horizontal plane. As the first fluid, water was assumed, and the viscosity was set to 0.001 [Pa · S], the density was 1000 [kg / m ³ ], and the surface tension was 0 [N / m]. Air was assumed as the second fluid, and it was simply set to 1/10 of the physical property value of the first fluid. The rotation speed was set to 24 rpm.

As a result of the numerical simulation, a pair of spiral vortices that spirally swirl around the pair of swirl axes SR were generated. Further, the directions of rotation of the pair of spiral vortices were opposite to each other (in FIG. 16, the vortex on the left side is clockwise and the vortex on the right side is counterclockwise). The generation of shear flow was confirmed between the pair of spiral vortices. Therefore, in the numerical simulation, the generation of torsional flow was confirmed, and the generation of self-sustaining turbulence was confirmed.

Next, the experiment will be described.

The experiment was carried out in substantially the same manner as in the first embodiment except for the shape of the stirring container 10. However, the rotation speed of the stirring container 10 was set to 24 rpm as in the above numerical simulation. The shape of the stirring container 10 is the same as the above numerical simulation.

FIG. 17 is a photograph showing the experimental results of a water filling rate of 50%. As shown in FIG. 17, it was confirmed that the turbulence was maintained. Although details are not shown, it was confirmed that the turbulent flow was similarly maintained when the rotation speeds were 12 rpm, 48 rpm, and 60 rpm.

As shown in the present embodiment, the shape of the inner surface 10a of the stirring container 10 may be an asymmetrical sphere, and has substantially the same effect as that of the first embodiment.

(Third Embodiment)
In the stirring device 1 of the third embodiment shown in FIG. 18, the shape of the stirring container 10 is different from that of the first and second embodiments. Except for the part related to this, it is substantially the same as the first and second embodiments. Therefore, the description of the parts shown in the first and second embodiments may be omitted.

The inner surface 10a of the stirring container 10 of the present embodiment has a cylindrical shape. Specifically, the inner surface 10a includes circular surfaces 10a1 and 10a2 facing each other and a cylindrical surface 10a3 connecting them.

The first fluid is filled so as to be in contact with all of the circular surfaces 10a1, 10a2 and the cylindrical surfaces 10a3. That is, in order to generate a torsional flow, the first fluid needs to be agitated by receiving a force from all of the circular surfaces 10a1, 10a2 and the cylindrical surfaces 10a3.

Also in this embodiment, the results of the above-mentioned stirring, especially the generation of twisted flow, were confirmed from both numerical simulations and experiments.

First, the numerical simulation will be described.

FIG. 19 is an explanatory diagram showing the results of numerical simulation. Note that FIG. 19 shows an XY cross section passing through the center point of the inner surface 10a. Further, in the present embodiment, since the central axis CA and the rotary axis RA are aligned with each other in the extending direction of the rotary shaft member 21, the central axis CA and the rotary shaft RA are not shown.

In the numerical simulation, the radius of the cylindrical shape was set to 50 mm and the length was set to 100 mm for the shape of the inner surface 10a. Therefore, the aspect ratio of the inner surface 10a in the XY cross section is 1: 1 (diameter: length). Then, the stirring container 10 was filled with the first fluid and the second fluid at a filling rate of 50% each, and the stirring container 10 was rotated by a rotation axis passing through the center point in the horizontal plane. As the first fluid, water was assumed, and the viscosity was set to 0.001 [Pa · S], the density was 1000 [kg / m ³ ], and the surface tension was 0 [N / m]. Air was assumed as the second fluid, and it was simply set to 1/10 of the physical property value of the first fluid. The rotation speed was set to 18 rpm.

As a result of the numerical simulation, a pair of spiral vortices that spirally swirl around the pair of swirl axes SR were generated. Further, the directions of rotation of the pair of spiral vortices were opposite to each other (in FIG. 19, the vortex on the left side is clockwise and the vortex on the right side is counterclockwise). The generation of shear flow was confirmed between the pair of spiral vortices. Therefore, in the numerical simulation, the generation of torsional flow was confirmed, and the generation of self-sustaining turbulence was confirmed.

Next, the experiment will be described.

The experiment was carried out in substantially the same manner as in the first embodiment except for the shape of the stirring container 10. However, the rotation speed of the stirring container 10 was set to 24 rpm. The shape of the stirring container 10 is the same as the above numerical simulation.

FIG. 20 is a photograph showing the experimental results of a water filling rate of 50%. As shown in FIG. 20, it was confirmed that the turbulence was maintained. Although details are not shown, it was confirmed that the turbulent flow was similarly maintained when the rotation speeds were 12 rpm, 48 rpm, and 60 rpm.

As shown in the present embodiment, the shape of the inner surface 10a of the stirring container 10 may be a closed cylindrical shape, and has substantially the same effect as that of the first embodiment. In the present embodiment, an example in which the aspect ratio of the inner surface 10a in the XY cross section is 1: 1 (diameter: length) has been described, but the aspect ratio is not particularly limited and is the length with respect to the diameter. It was confirmed that the number of twisting vortices increased to 2 pairs, 3 pairs, and so on as the value increased. For example, the aspect ratio may be 1: 2 (diameter: length). Further, an example of the filling rate of the first fluid of 50% is shown, but it is preferably less than 80%.

Although the specific embodiment of the present invention and the modification thereof have been described above, the present invention is not limited to the above-described embodiment and can be variously modified and carried out within the scope of the present invention.

For example, the shape of the inner surface 10a of the stirring container 10 may be various, such as a double cylindrical shape with both ends closed, a conical shape, or a gourd shape, in addition to the above. The twist flow that can occur at this time does not have to be an even number (pair), and may be at least one. Further, the rotation axis RA does not have to be set to extend in the horizontal plane. For example, the rotation axis RA may be set to be inclined within a range of about 30 ° from the horizontal direction. By limiting the inclination angle of the stirring container 10, stable stirring can be realized without the boundary changing significantly from the horizontal position.

Further, various first fluids to be agitated can be considered. For example, water and oil in emulsification (mixed flow of liquid and liquid), monomer or polymer and water in polymerization reaction process, slurry agitation in catalytic reaction process (mixed flow of solid and liquid), single-phase or double-phase non-Newtonian. Aeration target for fluid (pseudo-plastic fluid or plastic fluid), aeration stirring of oxygen such as bioreactor (mixed flow of gas and liquid), or mixed flow of solid (mud, etc.) and liquid in an anaerobic layer such as bioreactor It may be the first fluid of.

1 Stirrer 2 Experimental device 3 4 Camera 5 Stand wall 6 Rod lens 7 Laser source 10 Stirrer container 10a Inner surface 10a1, 10a2 Circular surface 10a3 Cylindrical surface 11 Base 11a Flange part 12 Lid 12a Flange part 13 Bearing 14 Hole part 20 Rotation mechanism 21 Rotating shaft member 22 Motor 23 Rotating body

Claims (23)

A stirring container having a closed rotating body-shaped inner surface and a rotating mechanism for rotating the stirring container are prepared.
The first fluid to be agitated and the second fluid that forms a boundary without being mixed with the first fluid are placed in the stirring container.
A stirring method comprising rotating the stirring container by the rotating mechanism and stirring the first fluid by generating a twisting flow in the first fluid. The inner surface of the stirring container has a central axis at a portion in contact with the first fluid, and has a shape of a rotating body formed by rotating a convex curve in a direction away from the central axis once around the central axis. The stirring method according to claim 1. The stirring method according to claim 2, wherein the central axis coincides with the rotation axis of the rotation of the stirring container by the rotation mechanism. The stirring method according to any one of claims 1 to 3, wherein the tilt angle of the rotation axis of the rotation of the stirring container by the rotation mechanism with respect to the horizontal direction is within 30 °. The stirring method according to claim 4, wherein the rotating shaft extends in the horizontal direction. The stirring method according to any one of claims 1 to 5, wherein the inner surface of the stirring container is spherical. The stirring method according to any one of claims 1 to 5, wherein the inner surface of the stirring container is an asymmetric sphere in which two partial spheres having different radii are joined. The stirring method according to any one of claims 1 to 5, wherein the inner surface of the stirring container is cylindrical. The stirring method according to any one of claims 1 to 8, wherein the first fluid contains at least one liquid and the second fluid contains at least one gas. The stirring method according to any one of claims 1 to 9, wherein the filling rate of the first fluid to the stirring container is 20% or more and 90% or less. The stirring method according to any one of claims 1 to 10, wherein the rotation of the stirring container is at a constant speed. A stirring container having a closed rotating inner surface containing a first fluid to be agitated and a second fluid that forms a boundary without being mixed with the first fluid.
A stirring device including a rotating mechanism for stirring the first fluid by rotating the stirring container and generating a twisting flow in the first fluid. The inner surface of the stirring container has a central axis at a portion in contact with the first fluid, and has a shape of a rotating body formed by rotating a convex curve in a direction away from the central axis once around the central axis. The stirring device according to claim 12. The stirring device according to claim 13, wherein the central axis coincides with the rotation axis of the rotation of the stirring container by the rotation mechanism. The stirring device according to any one of claims 12 to 14, wherein the tilt angle of the rotating axis of the rotating container by the rotating mechanism with respect to the horizontal direction is within 30 °. The stirring device according to claim 15, wherein the rotating shaft extends in the horizontal direction. The stirring device according to any one of claims 12 to 16, wherein the inner surface of the stirring container is spherical. The stirring device according to any one of claims 12 to 16, wherein the inner surface of the stirring container is an asymmetric sphere in which two partial spheres having different radii are joined. The stirring device according to any one of claims 12 to 16, wherein the inner surface of the stirring container is cylindrical. The stirring device according to any one of claims 12 to 19, wherein the first fluid contains at least one liquid and the second fluid contains at least one gas. The stirring device according to any one of claims 12 to 20, wherein the filling rate of the first fluid to the stirring container is 20% or more and 90% or less. The stirring device according to any one of claims 12 to 21, wherein the rotation of the stirring container is at a constant speed. It has a closed rotating body-like inner surface that houses a first fluid to be agitated and a second fluid that forms a boundary without mixing with the first fluid.
A stirring container that agitates the first fluid by generating a twisting flow in the first fluid by being rotated.

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