KR102065866B1 - Lift generator - Google Patents

Abstract

The lift generator 10 is located in front of the propulsion propeller 3 of the ship 1. The lift generator 10 has a wall portion 7 extending in the circumferential direction of rotating the extension line Ce of the central axis C of the propeller propeller 3. The wall part 7 forms the flow path which penetrates in the direction of the extension line Ce inside. In the airfoil, the outer surface forming the outer circumferential surface 7a of the wall portion 7 is bent inward to form a recess. The airfoil satisfies | dt / dx | ≦ 0.15 over the entire range from the set position where the thickness is maximum in the airfoil to the trailing edge. dx is a small change amount of the position coordinate x in the airfoil direction, dt is a small change amount of the thickness t with respect to dx, and | dt / dx | is a size of dt / dx.

Description

Lift generator

The present invention relates to a lift generator located in front of a propulsion propeller in a ship.

Conventionally, a duct may be provided in front of the propulsion propeller of the stern part of a ship as a lift generating body. By the rotation of the propeller, the lift generator generates water flow from the front side to the rear side of the ship. Since the cross section of the lift generator is made of airfoil, lift is generated on the lift generator by this flow. This lifting force has a component (a component facing forward) of the ship facing forward. As a result, the power for rotating the propeller is reduced. Such a lift generator is described as a duct in patent documents 1 and 2, for example.

Japanese Patent Laid-Open No. 2011-042204 Japanese Patent Registration No. 4079742

There is a need for a lift generator capable of further reducing the power for rotating the propeller.

That is, an object of the present invention is to provide a lift generator that can propel a ship larger when rotating the propeller with the same power as compared with a conventional lift generator (duct).

In order to achieve the above object, according to the present invention, in a ship provided with a propeller, a lift generator located in front of the propeller,

The lift generator has a wall portion extending in the circumferential direction of rotating the extension line of the central axis of the propeller propeller, the wall portion forms a flow path penetrating in the direction of the extension line on the inside,

In the setting range of the circumferential direction, the cross-sectional shape of the wall portion along the imaginary plane including the extension line is airfoil,

In the airfoil, the outer surface forming the outer circumferential surface of the wall portion is bent inward to form a recess,

The thickness of the airfoil gradually decreases as it moves backward from the set position at which the thickness is maximum,

The airfoil over the entire range from the set position to the trailing edge of the airfoil

| Dt / dx | ≤0.15

In this inequality, dx is a small change amount of the position coordinate x in the airfoil direction, dt is a small change amount of the thickness t with respect to dx, and dt / dx is a lift amount of dt / dx. A generator is provided.

In the present invention, the outer surface that forms the outer circumferential surface of the wall portion in the airfoil is bent inward to form a recess. As a result, the circulation of the flow in the airfoil is increased, and as a result, the pressure on the inner side is lowered and the lifting force is increased. By increasing the lifting force of the airfoil, the component toward the front of the lift of the airfoil also increases (hereinafter, this action is referred to as the increase of the component toward the lift front).

Further, in the present invention, the size of the ratio dt / dx of the small change amount dx of the position x in the chord direction and the small change amount dt of the thickness t at the position x is 0.15 or less (dx over the entire range from the set position to the trailing edge) (dx And dt have the same unit). Thereby, even if the above-mentioned concave portion is formed, the air resistance of the airfoil is suppressed small (hereinafter, this action is referred to as the action of reducing fluid resistance).

According to the present invention, the above-mentioned component increasing action toward the front of the lifting force and the reducing effect of the fluid resistance are combined, so that the ship can be driven with a larger power than the conventional lifting generator (for example, as described later). Comparison with Comparative Examples 1 and 2).

The above-mentioned lift generator can be configured as follows.

In the airfoil, the inner side surfaces forming the outer circumferential surface and the inner circumferential surface of the wall portion are each curved toward the flow path side.

Thus, each of the outer side and the inner side of the airfoil is curved inwardly as a whole. As a result, the fluid is easily peeled off from the airfoil (especially the inner surface), so that the fluid passing through the lift generator is disturbed and the flow rate is lowered. Thus, the flow of the flow rate is lowered into the propeller propeller. As a result, the efficiency of the propulsion propeller is improved (hereinafter, this action is referred to as an improvement effect of the propeller efficiency).

Therefore, the action of increasing the above-mentioned lift forward component, reducing the fluid resistance, and improving the propeller efficiency are combined, so that the ship can be driven even more with the same power as compared with the conventional lift generator.

The wall portion has a lower portion of the outer circumferential surface facing vertically downward,

The length of the lower portion in the direction of the extension line is smaller than the length of the upper portion of the wall portion.

Drag is likely to occur in the lower portion of the wall where the outer circumferential surface is vertically downward.

On the other hand, in the said structure, since the length of a lower part is made smaller than the length of an upper part in a wall part, drag in a lower part is suppressed.

The shape of the cross section of the lower end portion is airfoil but does not have the recess or is not airfoil.

As mentioned above, the recessed part or the cross section of a blade shape is unnecessary in the lower end part which a drag generate | occur | produces. Thereby, the cross-sectional shape of a lower part can be simplified.

The setting range includes at least a part of the range in the circumferential direction in which the outer peripheral surface of the wall portion is inclined upward.

This range can generate a great lift on the airfoil.

According to the present invention, since the outer surface of the airfoil is bent inwardly to form a recess, the lift force generated in the airfoil increases. As a result, the component toward the front of the lift of the airfoil also increases.

Moreover, the magnitude | size of the ratio dt / dx of the small amount of change dx of the position x in the chord direction, and the small amount of change dt of the thickness t in the said position x is 0.15 or less over the whole range from a setting position to a trailing edge. Thereby, even if it forms the recessed part mentioned above, fluid resistance of a blade shape is suppressed small.

This forward component of lifting force and the decrease in the fluid resistance of the airfoil are combined, so that the ship can be driven larger with the same power as compared with the conventional lifting generator.

1A shows a stern of a ship to which a lift generator according to an embodiment of the present invention is applied.
FIG. 1B is a view seen from the arrow BB direction in FIG. 1A.
FIG. 2A is a cross-sectional view taken along line II-II of FIG. 1B.
FIG. 2B is a cross-sectional view taken along the line II-II of FIG. 1B, showing other features of the airfoil.
It is a figure explaining the airfoil according to the comparative example 1 with the airfoil which concerns on the specific example of embodiment of this invention.
It is another figure explaining and comparing a specific example and the comparative example 1. FIG.
It is another figure explaining and comparing a specific example and the comparative example 1. FIG.
It is a figure explaining the airfoil concerning the airfoil according to the specific example of embodiment of this invention, and airfoil according to the comparative example 2. FIG.
4B is another diagram illustrating the comparison between Specific Example and Comparative Example 2. FIG.
5A shows the shape difference between the airfoil according to the specific example and the airfoil according to Comparative Example 2. FIG.
5B is another graph showing the difference in shape between the specific example and Comparative Example 2. FIG.
6 shows a modification of the lift generator.

Best Mode for Carrying Out the Invention A preferred embodiment of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the part common in each drawing, and the overlapping description is abbreviate | omitted.

1: A is a side view which shows the stern part 1a of the ship 1 to which the lift generating body 10 which concerns on embodiment of this invention was applied.

The ship 1 sails the sea, a lake, or a river. The ship 1 is a ship or a ship, for example. The ship 1 is provided with the propulsion propeller 3 in the stern part 1a. The propeller 3 may be a screw propeller. The propulsion propeller 3 is rotationally driven in water to generate forward thrust of the ship 1. The rotation of the propulsion propeller 3 generates a flow toward the propulsion propeller 3 in a direction from the front side to the rear side of the ship 1 (hereinafter referred to as backward). In addition, in this application, the front means the front side (the bow side) of the ship 1, and the rear means the back side (stern side) of the ship 1.

The lift generator 10 is provided in front of the propeller 3. That is, the lift generator 10 (foil 9 later) is disposed in the flow backward by the propeller 3. In FIG. 1A the lift generator 10 is located just in front of the propeller 3.

FIG. 1B is a view seen from the direction of arrow B-B in FIG. 1A. The lift generator 10 has a wall portion 7 extending in the circumferential direction (hereinafter, simply referred to as circumferential direction) for rotating the extension line Ce of the central axis C of the propeller propeller 3. This wall portion 7 forms an inner flow path 5 penetrating in the direction of the extension line Ce. Extension line Ce is located in this flow path 5. Meanwhile, in FIG. 1, the circumferential end surface of the upper end portion of the wall portion 7 of the lift generator 10 is coupled to the stern portion 1a, and the lift generator 10 is also connected to the stern portion through the coupling member 6. Is bound to 1a). However, the lift generator 10 may be coupled to the stern portion 1a by other means. The central axis C may be facing the hull centerline direction (left and right direction in FIG. 1A) of the ship 1, and may be inclined in one or both of the left and right and up and down of the ship 1 from this centerline direction.

FIG. 2A is a cross-sectional view taken along the line II-II of FIG. 1B. In the setting range of the circumferential direction (hereinafter simply referred to as the setting range), the cross-sectional shape of the wall portion 7 along the imaginary plane including the extension line Ce is the airfoil 9. This airfoil 9 is demonstrated based on FIG. In the setting range, the shape of the cross section at all the circumferential positions may be the same as the airfoil 9 described below.

The setting range includes at least the range θ1 (see FIG. 1B) in the circumferential direction in which the outer peripheral surface 7a of the wall portion 7 is inclined upward. In the present embodiment, the setting ranges are all ranges in which the wall portion 7 extends in the circumferential direction. In this case, the setting range in FIG. 1B is the range θ1, the circumferential range θ2 (see FIG. 1B) in which the outer circumferential surface 7a of the wall portion 7 is horizontally or inclined downward (see FIG. 1B), and the wall portion 7. The outer circumferential surface 7a has a range θ3 in the circumferential direction facing vertically downward.

A blade Bc of the airfoil 9 (that is, a straight line connecting the leading edge Pf and the trailing edge Pr of the airfoil 9 in FIG. 2A) is inclined from the central axis C of the propeller 3. . Moreover, the point on the chord Bc moves away from the extension line Ce of the central axis C as it moves to the front side. That is, as the point on the chord Bc shifts to the front side, the distance D1 of the point on the chord Bc and the extension line Ce becomes larger in the direction (radial direction) orthogonal to the extension line Ce. . As a result, lifting force having a component facing forward is generated in the airfoil 9. For convenience, the extension line Ce is shown in parallel in the vicinity of the airfoil 9 from the actual position in FIG. 2A.

In the airfoil 9 (ie, the contour of the airfoil 9), the outer surface 9a forming the outer circumferential surface 7a (see FIGS. 1A and 1B) of the wall portion 7 forms the recess 11. It is bent to the inner side (the flow path 5 side). In this embodiment, in the airfoil 9, the outer side surface 9a and the inner side surface 9b which form the inner peripheral surface 7b of the wall part 7 are each curved inward. On the other hand, the lift generator 10 is a propulsion propeller (so that turbulence due to fluid separation at the outer surface 9a and the inner surface 9b (in particular, the inner surface 9b) flows into the propeller propeller 3). Close to 3).

The thickness t of the airfoil 9 is maximum at the set position Ps in the chord direction. The chord direction is a direction parallel to the chord Bc. In this embodiment, the setting position Ps is located in the front side of the center of the bladeboard Bc (that is, the point at which the bladeboard Bc is divided into two). However, the setting position Ps may be the center of the chord Bc, and may be located behind the center of the chord Bc.

The thickness t of the airfoil 9 is the thickness in the direction orthogonal to the camber line Lc of the airfoil 9. The camber line Lc is a line extending from the leading edge Pf to the trailing edge Pr, and is a line at the same distance from the outer surface 9a and the inner surface 9b of the airfoil 9 (ie, one point in FIG. 2A). Dashed line). On the other hand, the thickness t of the blade 9 at the position coordinate x in the chord direction is the outer surface 9a perpendicular to the camber line Lc at the point on the camber line Lc where the position in the chord direction becomes the coordinate x. It is the length of the line segment extending from to the inner side surface 9b. The thickness t of the airfoil 9 gradually increases as it moves rearward from the leading edge Pf to the set position Ps, and gradually decreases as it moves rearward from the set position Ps to the trailing edge Pr.

As can be seen from FIG. 1A, the blade length (or dimension of the airfoil 9 in the extension line Ce direction) of the airfoil 9 of the cross section of the wall 7 decreases as it moves downward. Thus, the chord length of the bottom part of the wall part 7 (ie, the part of the range θ3) is smaller than the chord length of the top part of the wall part 7.

The lift generator 10 of the present embodiment has the following features A to C. FIG.

(Feature A)

In FIG. 2A, the airfoil 9 satisfies the following inequality over the entire range from the set position Ps to the trailing edge Pr.

| Dt / dx | ≤0.15

Here, dx is a small change amount of the position coordinate x in the chord direction of the airfoil 9, dt is a small change amount of the thickness t with respect to dx at the position coordinate x, and | dt / dx | is a size of dt / dx ( Absolute value). dt / dx may be a derivative of thickness t by position coordinate x. In other words, dt / dx is the ratio of dt to the small amount of change dx. The unit of position coordinate x and thickness t is the same. As | dt / dx | is 0.15 or less in the whole range from the set position Ps to the trailing edge Pr, the fluid resistance of the airfoil 9 is suppressed low.

(Feature B)

FIG. 2B is a cross-sectional view taken along the line II-II of FIG. 1B, but showing other features of the airfoil 9. The length of the blade string Bc is C, the maximum value of the thickness t of the blade 9 is tm, and the maximum distance between the blade string Bc and the outer surface 9a in the direction orthogonal to the blade direction is Dm. .

It is preferable that tm / C satisfies 0.05 ≦ tm / C ≦ 0.3.

Dm / tm preferably satisfies 0.06 <Dm / tm ≦ 0.4, 0.2 <Dm / tm ≦ 0.4, or 0.3 <Dm / tm ≦ 0.4.

Dm / tm is an index indicating the size of the recess 11. By setting the size of Dm / tm as described above, the circulation of the flow in the airfoil 9 becomes larger than in the case where there is no recess 11. As a result, the pressure of the inner surface 9b decreases and the lift force generated in the airfoil 9 increases. Therefore, the component toward the front of the lifting force of the airfoil 9 also becomes large.

(Feature C)

In FIG. 1A, the whole of the rear end 13 (that is, the rear end 13 extending in the circumferential direction) of the wall 7 is pushed when viewed from the hull centerline direction of the ship 1 (left-right direction in FIG. 1A). It is located in the area | region R which the propeller 3 rotates and passes through (it is called the passage area | region R of the propeller propeller 3 hereafter). Due to this configuration, all or almost all of the flows of which the flow rate is reduced as the turbulent flow as described above through the airfoil 9 flows into the passage region R of the propeller 3. As a result, the efficiency of the propulsion propeller 3 is improved more reliably.

However, according to the present invention, the lower end of the wall portion 7 may be located in the passage region R of the propulsion propeller 3 when viewed from the hull centerline direction of the ship 1. Also in this case, preferably, the extension line Ce of the central axis C of the propeller propeller 3 is located in the flow path 5 (that is, inside of the wall portion 7).

Next, the specific example of the airfoil 9 concerning this embodiment is demonstrated compared with the comparative example 1. FIG.

3A shows the airfoil 9 of the specific example according to the present embodiment and the airfoil of the comparative example (1). In FIG. 3A, the solid line represents a specific example and the broken line represents Comparative Example 1. FIG. The airfoil 9 of the comparative example 1 does not have a recess substantially in an outer side surface.

As shown in FIG. 3B, the lift of the same direction occurs in the airfoil of the specific example and the comparative example 1, but the lift of the specific example becomes larger than the comparative example 1. FIG. As a result, the component facing forward of lifting force becomes larger than a specific example.

FIG. 3C shows the effect of reducing the power (hereinafter referred to as the power reduction effect) for rotating the propulsion propeller 3 as a reduction in fluid resistance of the ship 1 when generating a constant thrust on the ship. That is, FIG. 3C is a value obtained by converting the power reduction effect when the thrust obtained by the rotation of the propeller 3 and the fluid resistance and lift force of the lift generator 10 are combined into the reduced amount of fluid resistance of the ship 1. Indicates. The results in FIG. 3C were obtained by simulation by CFD (computationalfluid dynamics). In this simulation, in Example and Comparative Example 1, airfoils were changed as shown in Fig. 3A, and the other conditions were the same.

As shown in FIG. 3C, when the fluid resistance reduction amount of Comparative Example 1 was 100%, the fluid resistance reduction amount of the specific example was 110% or more. Therefore, in the specific example, the fluid resistance (power) is about 10% or more lower than that of Comparative Example 1.

Next, the specific example of the airfoil 9 concerning this embodiment is demonstrated compared with the comparative example 2. FIG.

4A shows the airfoil of the airfoil 9 and the comparative example (2) of the specific example which concerns on this embodiment. In FIG. 4A, the solid line shows a specific example and is the same as the case of FIG. 3A, and the broken line shows the comparative example 2. FIG. Although the airfoil of the comparative example 2 has the recessed part of the magnitude | size similar to a specific example, the derivative dt / dx of thickness t by the position coordinate x of a chord | direction direction differs from a specific example.

5A is a graph showing the relationship between the position coordinate x in the chord direction and the thickness t of the airfoil 9. In FIG. 5A, the horizontal axis represents the coordinate x when the coordinate x of the leading edge Pf is 0 and the chord length is 1. In FIG. 5A, the vertical axis represents a value (thickness / extension length) obtained by dividing the thickness t of the airfoil 9 by the chord length.

5B is a graph showing the relationship between the position coordinate x in the chord direction and the differential dt / dx described above. In FIG. 5B, the horizontal axis represents the coordinate x when the coordinate x of the leading edge Pf is 0 and the chord length is 1. In FIG. 5B, the vertical axis represents the value of the derivative dt / dx.

In both the specific example and the comparative example 2, as for the thickness t of the airfoil 9, the coordinate x becomes the maximum at the set position Ps of 0.3 as shown in FIG. 5A.

In an embodiment, the size of dt / dx is smaller than 0.15 over the entire range from the set position Ps to the trailing edge Pr of the airfoil 9 (ie, the position of the rear end 13) as shown in FIG. 5B. . In Comparative Example 2, this is not done. That is, in the comparative example 2, the magnitude | size of dt / dx becomes 0.15 or more over the range from the position of coordinate x 0.86 to the rear end of a airfoil.

4B shows a value obtained by converting the power reduction effect into the amount of reduction in fluid resistance of a ship, as in the case of FIG. 3C. The results in FIG. 4B were obtained by simulation with CFD. In this simulation, the specific example and the comparative example 2 changed airfoils like FIG. 4A, FIG. 5A, and FIG. 5B, and made the other conditions the same.

As shown in FIG. 4B, when the fluid resistance reduction amount of Comparative Example 2 was 100%, the fluid resistance reduction amount of the specific example was slightly less than 115%. Therefore, in the specific example, the fluid resistance (power) is much reduced by about 15% closer than that of Comparative Example 2.

This invention is not limited to embodiment mentioned above, Of course, various changes can be added within the range of the technical idea of this invention. For example, any one of the following modifications 1-3 can be employ | adopted independently, and 2 or more of the modifications 1-3 can also be selected arbitrarily, and can be employ | adopted. In this case, the points not described below may be the same as described above.

(Change example 1)

The above-mentioned setting range in which the cross-sectional shape of the wall portion 7 is the airfoil 9 described above is not limited to the above description. For example, this setting range may not include part or all of one or both of the above-described ranges θ2 and θ3 shown in FIG. 1B. In addition, the setting range may include only a part of the range θ1. In this case, the setting range may not include part or all of one or both of the above ranges θ2 and θ3.

(Change example 2)

Although FIG. 6 is corresponded to FIG. 1B, the modified example 2 of the lift generator 10 is shown. As shown in FIG. 6, the inner flow passage 5 of the wall portion 7 may be opened vertically downward (radial direction). On the other hand, the flow path 5 may be opened also in another radial direction (that is, the direction orthogonal to the extension line Ce).

(Change example 3)

When a plurality of propulsion propellers 3 are provided in the stern portion 1a, a lifting force generator 10 may be provided in front of each propeller propeller 3.

(Change example 4)

The shape of the cross section of the lower end portion in the wall portion 7 is airfoil but may not have the recess 11. Alternatively, the shape of the cross section of the lower end portion may not be an airfoil.

1: boat 1a: stern
3: propeller 5: flow path
6: coupling member 7: wall portion
7a: outer circumference 7b: inner circumference
9: airfoil 9a: outer side
9b: inner side 10: lift generator
11: recess 13: rear end
Bc: Ikhyeon C: Central axis
Ce: Extension of the central axis
D1: Distance between the extension line of the central axis and the point of the phenomenon
Ps: Setting Position Pf: Leading Edge
Pr: trailing edge

Claims (5)

In the ship 1 provided with the propeller propeller 3, the lift generator 10 located in front of the propeller propeller,
The lift generator 10 has a wall portion 7 extending in the circumferential direction of rotating the extension line Ce of the central axis C of the propeller propeller 3, which wall portion is in the direction of the extension line Ce. The flow path 5 penetrating is formed inside,
In the setting range of the circumferential direction, the cross-sectional shape of the wall portion 7 along the imaginary plane including the extension line Ce is the airfoil 9 for generating a lift having a component facing forward,
In the airfoil 9, the outer surface 9a that forms the outer circumferential surface 7a of the wall portion 7 is bent inward to form the recessed portion 11,
The thickness t of the airfoil 9 becomes gradually smaller as it moves backward from the set position Ps at which the thickness t becomes the maximum,
The airfoil over the entire range from the set position Ps to the trailing edge Pr of the airfoil 9
| Dt / dx | ≤0.15
In this inequality, dx is a small change amount of the position coordinate x in the tip Bc direction of the airfoil 9, dt is a small change amount of the thickness t with respect to dx, and dt / dx | Is a lift generator, where dt / dx is magnitude. The method of claim 1,
In the airfoil (9), the lifting surface generator (9a) and the inner surface (9b) forming the inner circumferential surface (7b) of the wall portion (7) are each curved toward the flow path (5) as a whole. The method according to claim 1 or 2,
The wall portion 7 has a lower end portion of which the outer circumferential surface 7a faces vertically downward,
Lifting body in the direction of the extension line (Ce), the length of the lower portion is smaller than the length of the upper portion of the wall (7). The method of claim 3,
The shape of the cross section of the lower end portion is a airfoil, but does not have the concave portion (11), or is not a airfoil lift lifting body. The method according to claim 1 or 2,
The setting range is at least a portion of the range θ1 in the circumferential direction in which the outer circumferential surface 7a of the wall portion 7 is inclined upward, and the outer circumferential surface 7a of the wall portion 7 is inclined downward. A lift generator comprising at least a portion of the range θ2 in the circumferential direction.

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