Stirring blade, stirring device, stirring method

Abstract

The present invention provides a stirring blade or the like that can efficiently apply shear force to fluids with a Reynolds number of 300 or higher. [Solution] The stirring blade 3 is a stirring blade 3 that stirs a fluid F by rotating around a rotating shaft 30, and generates a flow of fluid F with a Reynolds number of 300 or more, in which, in a region of 5% or more of the flow, the ratio of the deformation velocity tensor to the fluid velocity gradient tensor, which is the sum of the deformation velocity tensor and the rotation velocity tensor, is 0.8 or more. It comprises a plurality of plate-shaped members 311 to 314 that are rotatable at different positions in the radial direction perpendicular to the axial direction in which the rotating shaft 30 extends. It comprises two to five plate-shaped members 311 to 314 that are rotatable at two to five different radial positions.

Description

Technical Field

[0001] This disclosure relates to stirring blades and the like.

Background Art

[0002] Patent Document 1 discloses a stirring device including a stirring blade that stirs a fluid accommodated in a vertically long stirring tank by rotation.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In such a stirring device, in order to promote mass transfer, it is desirable to efficiently apply a shear force (deformation force) to the fluid. Conventionally, by increasing the residence time of the fluid in the stirring tank, a sufficient shear force was applied to the fluid, so the length of the stirring tank tended to increase. In particular, it was difficult to efficiently apply a shear force to a fluid with a large inertial force having a Reynolds number of 300 or more.

[0005] This disclosure has been made in view of such circumstances, and an object thereof is to provide a stirring blade or the like that can efficiently apply a shear force to a fluid having a Reynolds number of 300 or more.

Means for Solving the Problems

[0006] In order to solve the above problems, a stirring blade according to an aspect of the present disclosure is a stirring blade that stirs a fluid by rotation around a rotation axis, and is a fluid flow having a Reynolds number of 300 or more. In a region of 5% or more within the flow, a flow is generated in which the ratio of the deformation velocity tensor in the velocity gradient tensor of the fluid, which is the sum of the deformation velocity tensor and the rotation velocity tensor, is 0.8 or more.

[0007] In this embodiment, for example, based on fluid analysis such as computational fluid dynamics (CFD), when the target is limited to a flow region with a Reynolds number of 300 or more, the ratio of the deformation velocity tensor (0.8 or more) and the ratio of the rotational velocity tensor (less than 0.2) that can not only uniformly mix the fluid but also efficiently apply shear force to the fluid to promote mass transfer, the region or particle percentage (5% or more) in the flow in which these ratios should be realized, and the configuration and shape of the impeller that can realize these with a high probability have been specifically identified. The specific configuration and shape of the impeller that can simultaneously realize various values ​​in this way can be designed through simulations based on CFD, etc. Such an impeller does not necessarily need to be complex and may be composed of a combination of simple plate-like members, as exemplified below.

[0008] Another aspect of the present disclosure is also an agitator. This agitator is an agitator that agitates a fluid by rotation around a rotating shaft, comprising two to five plate-like members rotatable at two to five different positions in the radial direction perpendicular to the axial direction in which the rotating shaft extends, wherein with respect to pairs of radially adjacent plate-like members, the radial spacing between them is 1.5 to 2.5 times the radial width of at least one of the plate-like members.

[0009] A further aspect of the present disclosure is an agitator. This agitator includes a rotor blade for rotating and agitating a fluid contained in a stirring tank, wherein the rotor blade generates a fluid flow in the stirring tank with a Reynolds number of 300 or more, and in a region of 5% or more of the flow, the ratio of the deformation velocity tensor to the fluid velocity gradient tensor, which is the sum of the deformation velocity tensor and the rotational velocity tensor, is 0.8 or more.

[0010] Another aspect of the present disclosure is a stirring method. This method is a stirring method in which a fluid contained in a stirring tank is stirred by the rotation of a stirring blade, wherein the stirring blade generates a fluid flow in the stirring tank in which the Reynolds number is 300 or more, and in a region of 5% or more of the flow, the ratio of the deformation velocity tensor to the fluid velocity gradient tensor, which is the sum of the deformation velocity tensor and the rotation velocity tensor, is 0.8 or more.

[0011] Furthermore, any combination of the above components, as well as any representations thereof converted into methods, apparatus, systems, recording media, computer programs, etc., are also included in this disclosure. [Effects of the Invention]

[0012] According to this disclosure, shear force can be efficiently applied to fluids with a Reynolds number of 300 or higher. [Brief explanation of the drawing]

[0013] [Figure 1] A schematic diagram shows the configuration of the stirring device according to the first embodiment. [Figure 2] A schematic diagram of the stirring apparatus according to the second embodiment is shown. [Figure 3] A schematic diagram shows the configuration of the stirring device according to the third embodiment. [Figure 4] A schematic diagram of one small stirring blade is shown, when the stirring blade is composed of a combination of multiple smaller stirring blades. [Figure 5] This shows an example of a fluid flow simulation using CFD. [Figure 6] This shows an example of a fluid flow simulation using CFD. [Figure 7] A schematic example of the number, dimensions, and arrangement of one or more plate-like members in each stirring section constituting the stirring blade is shown. [Figure 8] Figure 7 shows the results of CFD simulations for typical study examples. [Figure 9]Figure 7 schematically shows an example of the distribution of fluid particles where the ratio of the deformation velocity tensor E observed or simulated in preferred study example (a) is 0.8 or higher. [Figure 10] Figure 7 schematically shows an example of the distribution of fluid particles where the ratio of the deformation velocity tensor E observed or simulated in the undesirable study example (b) is 0.8 or higher. [Modes for carrying out the invention]

[0014] The following describes in detail the forms (hereinafter also referred to as embodiments) for carrying out this disclosure, with reference to the drawings. In the description and / or drawings, identical or equivalent components, members, processes, etc., are denoted by the same reference numerals, and redundant descriptions are omitted. The scale and shape of the illustrated parts are set for convenience in order to simplify the description and are not to be interpreted restrictively unless otherwise specified. The embodiments are illustrative and do not limit the scope of this disclosure in any way. Not all features or combinations thereof presented in the embodiments are necessarily essential to this disclosure. For convenience, embodiments are presented by breaking them down into components for each function and / or group of functions that realize them. However, one component in an embodiment may actually be realized by a combination of multiple components as separate entities, and multiple components in an embodiment may actually be realized by a single component as a whole. Furthermore, multiple embodiments and modifications may be disclosed in parallel, and any components of each embodiment and / or modification may be combined in any manner as long as they do not interfere with each other's functions.

[0015] FIG. 1 schematically shows the configuration of the stirring device 1 according to the first embodiment of the present disclosure. FIG. 2 schematically shows the configuration of the stirring device 1 according to the second embodiment of the present disclosure. FIG. 3 schematically shows the configuration of the stirring device 1 according to the third embodiment of the present disclosure. In the examples of these embodiments, the vertical direction (or longitudinal direction, height direction) in each figure coincides with the vertical direction, and the left-right direction (or lateral direction, width direction) in each figure coincides with the horizontal direction. Further, the axial direction in which the central axis of the stirring tank 2 and / or the rotation axis 30 of the stirring blade 3 extends later coincides with the vertical direction, i.e., the vertical direction, in each figure. Furthermore, the left-right direction, i.e., the horizontal direction, in each figure is also represented as the radial direction in order to define the diameter of the stirring tank 2 and the stirring blade 3. Note that the vertical direction, vertical direction, and axial direction in each figure may be different from each other. Similarly, the left-right direction, horizontal direction, and radial direction in each figure may be different from each other.

[0016] In the first embodiment of FIG. 1, the stirring device 1 includes a stirring tank 2 that houses a fluid F as an object to be stirred, and a stirring blade 3 that stirs the fluid F in the stirring tank 2 by rotation. The stirring tank 2 includes a cylindrical or circular tube-shaped straight body portion 21 that extends in the axial direction, and a bottom portion 22 that is provided continuously downward from the straight body portion 21. The capacity of the stirring tank 2 is arbitrary.

[0017] The inner peripheral wall or side wall of the straight body portion 21 has a circular cross-section in a top view (axial view), and its diameter D represents the tank diameter of the stirring tank 2. Note that the cross-section of the straight body portion 21 in a top view may be an arbitrary non-circular shape. In this case, the tank diameter D of the stirring tank 2 may be defined as the diameter of the inscribed circle of the cross-sectional shape of the straight body portion 21, or may be defined as the diameter of the circumscribed circle of the cross-sectional shape, or may be defined as an average value or intermediate value thereof.

[0018] An opening for introducing the fluid F into the stirring tank 2 is provided above the straight body portion 21 or the like. This opening is closed by a lid or the like during stirring of the fluid F by the stirring blade 3. Note that the fluid F may be supplied into the stirring tank 2 from a supply port such as a supply nozzle (not shown) provided on the side wall of the straight body portion 21 or the like.

[0019] The bottom 22 of the stirring tank 2 is formed in a curved shape that bulges downward from the lower end of the straight cylinder 21. The lowest part of the stirring tank 2 is formed at the center of the bottom 22 by the curved bulge. The bottom 22 may be formed in the shape of an inverted cone or an inverted frustocone, with the diameter decreasing downwards, or it may be formed in a planar shape with the axial direction as the normal direction.

[0020] A discharge port (not shown) may be provided at the bottom of the stirring tank 2 to discharge the fluid F after stirring is complete to the outside of the stirring device 1. This discharge port may be configured to be openable and closable by a discharge port opening / closing mechanism such as a valve. For example, when fluid F is introduced into the stirring tank 2 and stored, when the fluid F is stirred by the stirring blades 3, and when the concentration of fluid F is made uniform, a valve controlled to the closed state closes the discharge port. Also, when the fluid F, after stirring is substantially complete and the concentration has been made uniform, is discharged while being stirred by the stirring blades 3 as needed, a valve controlled to the open state opens the discharge port. The fluid F after stirring is complete may also be discharged from an opening in the upper part of the stirring tank 2, such as when the lid is open. Alternatively, the fluid F after stirring is complete may be discharged to the outside of the stirring tank 2 from a fluid discharge port such as a discharge nozzle that may be provided on the side of the straight body section 21.

[0021] The horizontal boundary line between the roughly cylindrical straight section 21 and the curved bottom section 22 is also called the tangent line TL. The vertical distance L between the lowest part of the agitated tank 2 (bottom section 22) and the surface or liquid level LL of the fluid F inside the agitated tank 2 is also expressed as the liquid level height or reference height. In this embodiment, the liquid level height L along the axial direction of the fluid F is greater than the tank diameter D along the radial direction of the agitated tank 2. Such a vertically elongated agitated tank 2 is preferable for forming a fluid flow (schematically shown by the arrows in Figure 1) that circulates largely along the vertical direction by the rotation of the agitator blades 3 and / or the circulation section 33 described later. Note that if the bottom section 22 is formed in a planar shape, the vertical distance L between the planar bottom section 22 (bottom plate) and the liquid level LL of the fluid F can be interpreted as the liquid level height.

[0022] The stirring blade 3 is rotatably mounted around a rotation axis 30 that substantially coincides with the vertical central axis of the stirring tank 2. The stirring blade 3 is rotatably mounted above the tangent line TL, i.e., within the straight cylinder portion 21 of the stirring tank 2. Although not shown in the illustration, a rotational drive unit such as a motor that generates rotational power, and a rotational power conversion unit such as a transmission or reduction gear that converts the rotational power into a desired rotational speed (or rotational velocity) or torque may be provided above the rotation axis 30. A lower bearing (not shown) may be provided below the rotation axis 30. The rotational speed of the stirring blade 3 is arbitrary. The detailed configuration of the stirring blade 3 will be described later.

[0023] Below the stirring blade 3 (below the plate-shaped members 311-314, which will be described in detail later), preferably below the tangent line TL, that is, within the bottom 22 of the stirring tank 2, a circulation unit 33 is provided that is rotatable around a rotation axis that substantially coincides with the vertical central axis of the stirring tank 2. The circulation unit 33 is separate from the stirring blade 3 and may rotate independently of the stirring blade 3 by a different rotation axis (not shown).

[0024] The circulation section 33 receives the downward flow from the top of the stirring blade 3 and discharges it to the outer circumference of the stirring tank 2. As a result, as schematically illustrated by the arrows, an upward flow of fluid F is formed along the inner circumferential wall of the stirring tank 2. When this upward flow rises to near the liquid level LL, it changes to a flow toward the inner circumference where the rotating shaft 30 is located, and then descends further to be supplied to the top of the stirring blade 3. This fluid F is stirred by the stirring blade 3 as it descends, and then circulates again in a large area within the stirring tank 2 by the circulation section 33. The circulation section 33 for generating such a circulating flow can be composed of any discharge type of fluid blade, such as a paddle blade, turbine blade, or swept blade. The circulation section 33 may be formed integrally with the lower part of the plate-shaped members 311 to 314, which will be described in detail later.

[0025] In the second embodiment shown in Figure 2, instead of the circulation unit 33 for generating circulating flow within the stirring tank 2 as in the first embodiment shown in Figure 1, an external circulation mechanism 42, such as a pump, is provided to circulate the fluid F outside the stirring tank 2. As schematically shown by the arrows in Figure 2, the fluid F, after being stirred by the stirring blades 3 while descending, is drawn out of the stirring tank 2 from the bottom 22. This fluid F is then lifted up to the top of the straight section 21 of the stirring tank 2 via the external circulation mechanism 42, such as a pump, and reintroduced into the stirring tank 2 to be supplied again to the stirring blades 3.

[0026] In the third embodiment shown in Figure 3, instead of circulating the fluid F inside and outside the stirring tank 2 by the circulation unit 33 in the first embodiment shown in Figure 1 or the external circulation mechanism 42 in the second embodiment shown in Figure 2, the fluid F flows, in principle, only once in a specific direction from one end to the other of the axially elongated stirring tank 2. In the example shown in Figure 3, the stirring tank 2 is axially elongated and substantially cylindrical or circular in shape. Preferably, the central axis of this stirring tank 2 coincides with the rotation axis 30 of the stirring blade 3.

[0027] The flat bottom 22 (i.e., bottom surface) of the stirring tank 2 is provided with a first fluid port 23 through which the fluid F can pass in virtually one direction, and the flat top 24 (i.e., top surface) of the stirring tank 2 is provided with a second fluid port 25 through which the fluid F can pass in virtually one direction. In the example shown in Figure 3, the first fluid port 23 acts as a fluid supply port, and the fluid F is continuously supplied upward, while the second fluid port 25 acts as a fluid discharge port, and the fluid F is continuously discharged upward. This type of stirring tank 2 or stirring device 1 can also be described as a continuous type because the fluid F is continuously supplied and discharged in a specific direction.

[0028] The fluid F enters the stirring tank 2 through the fluid supply port 23 and exits the stirring tank 2 through the fluid discharge port 25, during which time it is stirred by the stirring blades 3. The stirring blades 3 are axially elongated, similar to the stirring tank 2, and have a height H that covers substantially the entire axial length (i.e., height) of the stirring tank 2 (for example, 90% or more). As will be described later, the stirring blades 3 in this embodiment are composed of elongated plate-like members extending along the axial direction, but the height H of the entire stirring blade 3 may be covered by substantially one plate-like member having a height H, or the height H of the entire stirring blade 3 may be covered by arranging multiple plate-like members having a height h significantly smaller than the height H along the axial direction, as schematically shown in Figure 3. These plate-like members, regardless of their height or number, are rotatable around a common rotation axis 30.

[0029] Figure 4 schematically shows one small stirring blade 3 when the stirring blade 3 with height H is composed of a combination of multiple small stirring blades 3 of height h, as shown in Figure 3 (although not shown, substantially identical small stirring blades 3 are arranged axially above and / or below it). The following description of this small stirring blade 3 (hereinafter referred to as stirring blade 3 for convenience) also applies to the stirring blade 3 in the circulating stirring device 1 shown in Figures 1 and 2.

[0030] The stirring blade 3 comprises a plurality of plate-like members 311 to 314 that are rotatable circumferentially (in a rotational direction perpendicular to the axial and radial directions) about the rotating shaft 30 at different radial positions in the radial direction (left-right direction in Figure 4) perpendicular to the axial direction (up-down direction in Figure 4) in which the rotating shaft 30 extends. Each of the plurality of plate-like members 311 to 314 extends substantially parallel to each other along the axial direction. In the example in Figure 4, stirring sections 31, each composed of four plate-like members 311 to 314, are provided on the left and right sides of the rotating shaft 30.

[0031] The number of stirring units 31 is arbitrary; as shown in Figure 4, there may be two, one, or three or more. In order to generate the most homogeneous fluid F flow possible within the stirring tank 2, it is preferable that the multiple stirring units 31 be arranged at circumferential positions (angles) that are point-symmetric with respect to the rotation axis 30 in an axial view (top or bottom view in Figure 4).

[0032] For example, if two stirring units 31 are provided, it is preferable that the two stirring units 31 be positioned at circumferential positions that are point-symmetric with respect to the rotation axis 30 (for example, at the 0° position and the 180° position), as shown in Figure 4. If four stirring units 31 are provided, it is preferable that the four stirring units 31 be positioned at circumferential positions that are point-symmetric with respect to the rotation axis 30 (for example, at the 0° position, the 90° position, the 180° position and the 270° position). In cases where an even number of stirring units 31 are provided, it is preferable that the two opposite stirring units 31 be configured symmetrically with respect to the rotation axis 30 in the plane including the rotation axis 30, as shown in Figure 4.

[0033] The multiple plate-shaped members 311 to 314 constituting each stirring section 31 are interconnected by radially extending rod-shaped connecting members 32, and are able to rotate integrally around the rotation axis 30. The connecting members 32 are preferably as thin as possible so as not to obstruct the flow of fluid F mainly generated by the plate-shaped members 311 to 314.

[0034] The shape and dimensions of each plate-like member 311-314 in each stirring section 31 are arbitrary, but it is preferable that the axial height h and circumferential thickness are common to all plate-like members 311-314. On the other hand, the radial widths w1-w4 of each plate-like member 311-314 may be common to each other or different. Also, the radial spacing g1-g3 of each plate-like member 311-314 and / or the radial spacing g0 between the innermost first plate-like member 311 and the rotating shaft 30 (zero if the first plate-like member 311 directly protrudes from the rotating shaft 30) may be common to each other or different. The three-dimensional dimensions, spacing, radial positions, etc. of the multiple plate-like members 311-314 in each stirring section 31 are preferably adjusted or optimized based on fluid analysis such as computational fluid dynamics (CFD) so that the desired flow described later is generated.

[0035] Furthermore, as shown in the example in Figure 3, when the small stirring blades 3 shown in Figure 4 are arranged in a line along the axial direction, the configuration of the multiple small stirring blades 3 arranged at different axial positions is as follows: All small stirring blades 3 may be substantially the same or different. Furthermore, even if the three-dimensional dimensions, spacing, radial position, etc., of the multiple plate-shaped members 311 to 314 constituting each stirring section 31 are substantially the same across all small stirring blades 3, the radial position where each stirring section 31 is provided may differ, for example, between two small stirring blades 3 adjacent to each other in the axial direction.

[0036] For example, suppose a small stirring blade 3 having two stirring sections 31, as shown in Figure 4, has each stirring section 31 positioned at 0° and 180° in an axial view. In this case, for example, in a small stirring blade 3 not shown, located above it, the two stirring sections 31 may be positioned at circumferential positions different from (or offset from) 0° and 180° in an axial view (e.g., 90° and 270°, 45° and 225°, 30° and 210°). Such rotational position differences or offsets between different small stirring blades 3 (e.g., 90°, 45°, 30°) can also be adjusted or optimized based on CFD or the like to generate the desired flow described later.

[0037] In Figure 4, fluid F supplied from below (another small agitator blade 3, not shown, or fluid supply port 23) is sheared or refined by the rotating small agitator blade 3 shown, and then sent further upward (another small agitator blade 3, not shown, or fluid outlet 25). The flow of fluid F generated by the rotating agitator blade 3 can be simulated by fluid analysis based on CFD, etc.

[0038] Figures 5 and 6 show examples of CFD simulations of fluid F flow. Figure 5 visualizes the velocity of fluid F flow using arrows (vectors) in a cross-section with the axial direction as the normal direction. In this simulation example, three plate-like members 311-313 are arranged radially (vertical direction in Figure 5) and rotated along the circumferential direction (leftward in Figure 5), generating a rightward flow of fluid F. The fluid F flows from the left in Figure 5 into the two gaps (hereinafter also referred to as slits) between the three plate-like members 311-313. As the flow velocity is increased at this time, the arrows representing velocity are locally larger inside and / or at the outlet of each gap.

[0039] Figure 6 visualizes the vortices in the fluid F generated by three plate-like members 311-313 (common in height h and thickness t), similar to those in Figure 5, using arrows (vectors representing vorticity). It can be seen that large localized vortices are generated when the fluid F passes through the two slits in the three plate-like members 311-313.

[0040] In this embodiment, using CFD as described above, a numerical index was found that enables the impeller 3 to efficiently stir or shear the fluid F when the target is limited to a flow region with a Reynolds number of 300 or higher. Furthermore, it was confirmed that an impeller 3 satisfying this numerical index can actually be designed using CFD. In particular, it was confirmed that an impeller 3 satisfying this numerical index can actually be designed by adjusting various parameters shown in Figures 4 to 6 (for example, the height h, thickness t, width w1 to w4, and spacing g0 to g3 of each plate-like member). Here, the Reynolds number Re is the density of the fluid F ρ [kg / m³]. 3 It is defined by the following formula, using the rotational speed n [1 / s] of the impeller 3, the blade diameter d [m] of the impeller 3, and the viscosity μ [Pa·s] of the fluid F.

number

[0041] Specifically, in this embodiment, we focused on the velocity gradient tensor ∇u of the fluid F and its constituent elements, the deformation velocity tensor E and the rotational velocity tensor Ω, in CFD. The velocity gradient tensor ∇u of the fluid F is the sum of the deformation velocity tensor E and the rotational velocity tensor Ω (i.e., ∇u = E + Ω). In shearing or refinement of the fluid F, the deformation velocity tensor E, which governs the deformation of the fluid F particles, is important. Therefore, it is considered important to increase the ratio of the deformation velocity tensor E (i.e., decrease the ratio of the rotational velocity tensor Ω) in the velocity gradient tensor ∇u, which is the sum of the deformation velocity tensor E and the rotational velocity tensor Ω.

[0042] In this embodiment, the ratio of such deformation rate tensor E was defined by the following equation.

number

[0043] Figure 7 schematically shows 13 different examples (a) to (m) of the number, dimensions, and arrangement of one or more plate-like members in each stirring section 31 that constitutes the stirring blade 3. In this figure, the vertical direction is the radial direction, and a rotation axis 30 (not shown) is located below. The left-right direction in this figure is the circumferential direction in which the stirring section 31 is rotated. The black rectangles in each example (a) to (m) schematically represent the plate-like members.

[0044] For example, the stirring part 31 of the study example (a) includes three plate-like members 311 to 313 in order from the inner peripheral side (lower side in FIG. 7) close to the rotating shaft 30. Each of the plate-like members 311 to 313 has a common thickness t (for example, 3 mm) and widths w1 to w3 that are slightly different from each other (for example, w2 < w1 < w3). Also, the two intervals g1 and g2 in the radial direction of the three plate-like members 311 to 313 are such that the interval g1 (for example, 9 mm to 11 mm) on the inner peripheral side close to the rotating shaft 30 is larger than the interval g2 (for example, 7 mm to 9 mm) on the outer peripheral side (that is, g1 > g2).

[0045] FIG. 8 shows the results of a CFD simulation for a typical study example as shown in FIG. 7. The typical diameter of the particles of the fluid F in this simulation was set to 1 mm to 2 mm. On the horizontal axis, each study example is classified according to the number and arrangement of the slits. The stirring part 31 with "0" slits corresponds to the study example (b) without slits in FIG. 7. The stirring part 31 with "outer 1" slits corresponds to the study example (e) in which one slit is closer to the outer peripheral side in FIG. 7. Although not shown, for the study example (f) in which one slit is closer to the inner peripheral side in FIG. 7, study results equivalent to those of the study example (e) were obtained.

[0046] The stirring part 31 with "unequal 2" slits corresponds to the study example (a) in which two slits are arranged at different intervals g1 and g2 in FIG. 7. Although not shown, for the study example (d) in which the thickness t is smaller than that of the study example (a) (for example, about 1.5 mm, which is half of about 3 mm in the study example (a)), study results equivalent to those of the study example (a) were obtained. Also, although not shown, for the study examples (j) to (m) in which the non-uniform arrangement of the two slits is different from that of the study example (a), study results equivalent to those of the study example (a) were obtained.

[0047] The stirring section 31 with "evenly spaced 2" slits, although not shown in Figure 7, is the same as in study example (a) where the widths g1 and g2 of the two slits are equal. The stirring section 31 with "evenly spaced 3" slits corresponds to study example (i) in Figure 7, where the three slits are arranged at substantially equal intervals. The stirring section 31 with "evenly spaced 4" slits corresponds to study example (h) in Figure 7, where the four slits are arranged at substantially equal intervals. The stirring section 31 with "evenly spaced 5" slits corresponds to study example (g) in Figure 7, where the five slits are arranged at substantially equal intervals.

[0048] The vertical axis in Figure 8 shows the proportion of fluid particles (or regions within the fluid F flow where the deformation rate tensor E ratio is 0.8 or higher) out of all particles (or the entire region within the fluid F flow with a Reynolds number of 300 or higher) contained in the fluid F flow with a Reynolds number of 300 or higher. As mentioned above, fluid particles with a deformation rate tensor E ratio of 0.8 or higher play a leading role in the shearing or refinement of the fluid F; therefore, a higher proportion of these particles indicates higher shearing or refinement performance of the stirring section 31 or the stirring blade 3.

[0049] As shown in Figure 8, in the study examples corresponding to "outermost 1" (e) (and study example (f)), "uneven 2" (a) (and study examples (d)(j)(k)(l)(m)), the study example for "even 2", the study example corresponding to "even 3" (i), and the study example corresponding to "even 4" (h), fluid particles with a deformation rate tensor E ratio of 0.8 or higher were realized in a high proportion of 5% (0.05) or more within the flow of fluid F with a Reynolds number of 300 or higher.

[0050] As described above, it was found that when the number of slits provided in the stirring section 31 is between one and four, that is, when the number of plate-like members provided in the stirring section 31 is between two and five, the proportion of fluid particles with a deformation velocity tensor E ratio of 0.8 or higher can be increased, thereby realizing a stirring blade 3 with high shear performance. However, when the number of slits provided in the stirring section 31 is five or more, that is, when the number of plate-like members provided in the stirring section 31 is six or more, the width of each slit becomes narrower, preventing fluid F particles from passing through efficiently, and thus the ratio of the deformation velocity tensor E could not be sufficiently increased.

[0051] Furthermore, in the above examples (a), (d), (e), (f), (h), (i), (j), (k), (l), and (m) in which high shear performance was obtained, the radial spacing between pairs of adjacent plate-like members in the radial direction (vertical direction in Figure 7) was adjusted to 1.5 to 2.5 times the radial width of at least one of the plate-like members. It was confirmed that this is important in increasing the proportion of fluid particles with a deformation rate tensor E ratio of 0.8 or higher.

[0052] Furthermore, in the above-mentioned study examples (a), (d), (e), (f), (h), (i), (j), (k), (l), and (m) in which high shear performance was obtained, the thickness t of each plate-like member in the circumferential direction (left-right direction in Figure 7) was adjusted to 2% to 10% of the total width (e.g., 30 mm to 40 mm) in the radial direction (up-down direction in Figure 7) of the stirring section 31 or stirring blade 3. It was confirmed that this is important in increasing the proportion of fluid particles with a deformation rate tensor E ratio of 0.8 or higher. Although not shown in the illustration, in the study example (c) in Figure 7, where the thickness t is large and outside the adjustment range, energy loss occurs when the fluid F passes through the thick slit in the circumferential direction, resulting in an insufficient proportion (less than 5%) of fluid particles with a deformation rate tensor E ratio of 0.8 or higher.

[0053] Among the examples of studies that yielded high shear performance, in particular, in the study example (e) (and study example (f)) corresponding to "outermost 1", the study example (a) (and study examples (d)(j)(k)(l)(m)) corresponding to "uneven 2", and the study example for "even 2", fluid particles with a deformation rate tensor E ratio of 0.8 or higher were realized in a remarkably high proportion of 5.35% (0.0535) to 5.70% (0.0570) of the fluid flow F with a Reynolds number of 300 or higher.

[0054] Figure 9 schematically shows an example of the distribution of fluid particles with a deformation velocity tensor E ratio of 0.8 or higher, as observed or simulated in preferred study example (a) in Figure 7. Each plot in this figure represents a single fluid particle with a deformation velocity tensor E ratio of 0.8 or higher. As mentioned above, the proportion of fluid particles with a deformation velocity tensor E ratio of 0.8 or higher is relatively small, just over 5% of the total, even in study example (a). In the example in Figure 9, fluid particles with a deformation velocity tensor E ratio of 0.8 or higher appear to be distributed in significantly larger quantities than just over 5%, but this is because these fluid particles observed in different axial directions (directions perpendicular to the plane of the paper in Figure 9) are superimposed.

[0055] Figure 10 schematically shows an example of the distribution of fluid particles with a deformation velocity tensor E ratio of 0.8 or higher, as observed or simulated in the unfavorable study example (b) in Figure 7. Compared to the favorable study example (a) in Figure 9, it can be seen that there are significantly fewer fluid particles with a deformation velocity tensor E ratio of 0.8 or higher. Thus, according to the favorable study example (a), etc., the proportion of fluid particles with a deformation velocity tensor E ratio of 0.8 or higher in the fluid flow of the fluid F can be significantly increased, and the stirring performance or shearing performance of the stirring section 31 or the stirring blade 3 can be significantly improved.

[0056] The above examples targeted flow regions with a Reynolds number of 300 or higher, but the stirring blade 3 or stirring device 1 according to this disclosure is also applicable to flow regions with a Reynolds number of 1000 or higher.

[0057] The present disclosure has been described above based on embodiments. Various modifications are possible for each component and each combination of processes in the exemplary embodiments, and it will be obvious to those skilled in the art that such modifications are included within the scope of the present disclosure.

[0058] The configuration, operation, and function of each device and method described in the embodiments can be realized by hardware resources or software resources, or by the cooperation of hardware resources and software resources. Hardware resources include, for example, processors, ROMs, RAMs, and various integrated circuits. Software resources include, for example, operating systems and application programs. [Explanation of Symbols]

[0059] 1. Agitator, 2. Agitator, 3. Agitator blade, 21. Straight section, 22. Bottom section, 30. Rotating shaft, 31. Agitator section, 311-314. Plate-shaped members.

Claims

1. A stirring blade that agitates a fluid by rotating around a rotating axis, A fluid flow with a Reynolds number of 300 or higher generates a flow in which, in a region of 5% or more of the flow, the ratio of the deformation velocity tensor to the fluid velocity gradient tensor, which is the sum of the deformation velocity tensor and the rotational velocity tensor, is 0.8 or higher. Agitator blade.

2. The impeller according to claim 1, which generates a fluid flow with a Reynolds number of 1000 or more, wherein in a region of 5% or more of the flow, the ratio of the deformation velocity tensor to the velocity gradient tensor is 0.8 or more.

3. The impeller according to claim 1, which generates a fluid flow with a Reynolds number of 300 or more, wherein in a region of 5.35% to 5.70% of the flow, the ratio of the deformation velocity tensor to the velocity gradient tensor is 0.8 or more.

4. The stirring blade according to any one of claims 1 to 3, comprising a plurality of plate-shaped members that are rotatable at different positions in the radial direction perpendicular to the axial direction in which the rotation shaft extends.

5. The stirring blade according to claim 4, comprising two to five plate-shaped members that are rotatable at two to five different radial positions.

6. The stirring blade according to claim 4, wherein, with respect to a pair of two radially adjacent plate-shaped members, the radial distance between them is 1.5 to 2.5 times the radial width of at least one of the plate-shaped members.

7. The stirring blade according to claim 4, wherein the thickness of each plate-shaped member in the circumferential direction perpendicular to the axial and radial directions is 2% to 10% of the total radial width of the stirring blade.

8. The system comprises at least three plate-like members that are rotatable at at least three different radial positions, The radial spacing between the at least three plate-like members is larger on the inner circumference side closer to the axis of rotation. The stirring blade according to claim 4.

9. The stirring blade according to claim 4, wherein each of the plurality of plate-like members extends along the axial direction.

10. A stirring blade that agitates a fluid by rotating around a rotating axis, The rotating shaft comprises two to five plate-shaped members that are rotatable at two to five different positions in the radial direction perpendicular to the axial direction in which the rotating shaft extends, With respect to a pair of two plate-shaped members adjacent in the radial direction, the radial distance between them is 1.5 to 2.5 times the radial width of at least one of the plate-shaped members. Agitator blade.

11. The stirring blade according to claim 10, wherein a circulation section rotatable around the rotation axis is provided below the plate-shaped member.

12. A stirring device equipped with a stirring blade that stirs a fluid contained in a stirring tank by rotation, The impeller generates a fluid flow in the stirring tank with a Reynolds number of 300 or more, where, in a region of 5% or more of the flow, the ratio of the deformation velocity tensor to the fluid velocity gradient tensor (which is the sum of the deformation velocity tensor and the rotational velocity tensor) is 0.8 or more. A stirring device.

13. A stirring method in which a fluid contained in a stirring tank is stirred by the rotation of a stirring blade, The aforementioned impeller generates a fluid flow in the stirring tank in which the Reynolds number is 300 or higher, and in a region of 5% or more of the flow, the ratio of the deformation velocity tensor to the fluid velocity gradient tensor, which is the sum of the deformation velocity tensor and the rotational velocity tensor, is 0.8 or higher. A stirring method.

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