KR101780910B1 - Duct device - Google Patents

Abstract

The duct device 1 includes a duct 2 disposed at least in the vicinity of the rotation axis of the propeller in front of the propeller 101 provided at the stern of the hull and a stay 3 connecting at least a part of the duct and the hull Respectively. The cross section of the duct is a wing shape, and the angle formed by the wing-like chord line and the rotation axis is parallel to the line, and the midpoint of the chord line and the rotation axis is smaller than the first part of the duct and the first part with respect to the circumferential direction of the rotation axis. Is different in the second portion of the other duct.

Description

DUCT DEVICE {DUCT DEVICE}

The present invention relates to a duct device of a ship.

BACKGROUND ART [0002] In the technical field of ships, for example, a ship having a duct device as disclosed in Patent Document 1 is known.

Japanese Laid-Open Patent Publication No. 2008-137462

By arranging the duct device at the stern of the ship, energy saving effect is obtained for the ship. By improving the duct device, a higher energy saving effect can be expected.

It is an object of the present invention to provide a duct device of a ship capable of obtaining an energy saving effect.

A first aspect of the present invention is a hull structure comprising a duct disposed at least at a part around a rotation axis of the propeller in front of a propeller provided at a stern of a hull and a stay connecting at least a part of the hull with the duct, Wherein an angle formed by the wing chord line and a line parallel to the rotation axis and a distance between a midpoint of the chord line and a distance between the rotation axis and the first portion of the duct, And a ducting device that is different in the second portion of the duct than in the first portion with respect to the circumferential direction of the rotating shaft.

In the duct device according to the present invention, at least a part of the duct is disposed above the rotary shaft, the first portion includes an upper end portion of the duct, and the second portion includes a side end portion of the duct Wherein the angle of the first portion is greater than the angle of the second portion and the distance of the first portion may be less than the distance of the second portion.

In the duct device according to the present invention, the duct has a front end portion defining an inlet port and a rear end portion opposing the propeller and defining an outlet port having a different size and shape from the inlet port, and the outlet port The inner surface of the upper end of the rear end portion protrudes toward the rotating shaft and the inner surface of the upper end portion of the front end portion may not protrude toward the rotating shaft.

In the duct apparatus according to the present invention, the cross section of the stay may be a wing shape.

A second aspect of the present invention is a straddle-type straddle-type straddle-type straddle-type straddle-type straddle-type straddle-type straddle- Sectional view of the duct device.

In the duct device according to the present invention, the stay may be inclined such that the front edge of the wing-like chord line is disposed above the rear edge.

In the duct device according to the present invention, the stay has an inner end connected to the hull and an outer end disposed outside the inner end with respect to the radial direction of the propeller and connected to the duct , The angle formed by the wing-like chord line and the horizontal plane may be different between the third portion of the stay and the fourth portion of the stay different from the third portion with respect to the radial direction.

In the duct device according to the present invention, the chord line at the inner end of the stay is inclined so that the leading edge of the wing shape is disposed above the trailing edge, and the chord line at the outer edge of the stay May be inclined so that the leading edge of the wing shape is disposed below the trailing edge.

In the duct apparatus according to the present invention, the stay includes first and second stays arranged above the rotational axis of the propeller, and with respect to the circumferential direction of the rotational axis, the first stay and the second stay, May be less than 90 degrees.

In the duct apparatus according to the present invention, the duct may be arranged so as to surround a part of the rotary shaft above the rotary shaft of the propeller.

According to the present invention, an energy saving effect can be obtained.

1 is a side view schematically showing an example of a duct apparatus of a ship according to the first embodiment.
2 is a front view schematically showing an example of a duct apparatus of a ship according to the first embodiment.
3 is a perspective view schematically showing an example of a duct apparatus of a ship according to the first embodiment.
4 is a cross-sectional view showing an example of a duct according to the first embodiment.
5 is a diagram showing an example of the outline of the front end portion and the outline of the rear end portion of the duct according to the first embodiment.
6 is a cross-sectional view showing an example of the stay according to the first embodiment.
7 is a diagram schematically showing an example of a duct apparatus of a ship according to the second embodiment.
8 is a diagram schematically showing an example of a duct apparatus of a ship according to the third embodiment.
9 is a diagram schematically showing an example of a duct apparatus of a ship according to a fourth embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto. The requirements of the respective embodiments described below can be appropriately combined. In addition, some components may not be used.

≪ First Embodiment >

The first embodiment will be described. 1 is a side view schematically showing an example of a duct device 1 of a ship according to the present embodiment. 2 is a front view schematically showing an example of a duct apparatus 1 of a ship according to the present embodiment, which corresponds to a view seen from the direction of arrow A-A in Fig. 3 is a perspective view schematically showing an example of a duct apparatus 1 of a ship according to the present embodiment.

1, the ship includes a propeller 101 provided at the stern 100B of the ship 100, a duct device 1 disposed in front of the propeller 101, And a disposed key 102. The duct device (1) is arranged at the stern (100B) of the hull (100). The propeller (101) is connected to a power source mounted on the hull (100) through a shaft (103). The power source includes at least one of an engine such as a diesel engine and a motor. The hull 100 has a stern tube 104 and the shaft 103 is rotatably supported by the stern tube 104. The power source rotates the propeller (101) through the shaft (103). The propeller 101 rotates about the rotation axis AX. As the propeller (101) rotates, the ship is stopped.

By the rotation of the propeller 101, the ship advances to the forward side. A forward bow is disposed with respect to the advancing direction of the advancing ship, and a stern (100B) is disposed behind. In the following description, the front direction is referred to simply as the front direction and the rear direction is referred to as the rear direction as appropriate with respect to the traveling direction of the advancing ship with respect to the traveling direction of the advancing ship. The direction orthogonal to the traveling direction within the horizontal plane is appropriately referred to as the width direction.

In the following description, a direction parallel to the rotation axis AX is appropriately referred to as an axial direction, a radial direction with respect to the rotation axis AX is appropriately referred to as a radial direction, a rotation direction about the rotation axis AX Is appropriately referred to as a circumferential direction.

The duct device 1 is provided with a duct 2 disposed in front of the propeller 101 and a stay 3 connecting at least a part of the duct 2 and the hull 100 to each other. The duct 2 is disposed at least in the vicinity of the rotation axis AX of the propeller 101 in front of the propeller 101. [ The duct 2 may also be referred to as a nozzle 2. The stay 3 may be referred to as a column 3 or may be referred to as a connecting plate 3. In the present embodiment, the stay 3 connects the duct 2 and the stern tube 104 of the hull 100.

In the present embodiment, at least a part of the duct 2 is disposed above the rotation axis AX of the propeller 101. [ In the present embodiment, the duct 2 is arranged so as to surround a part of the rotation axis AX above the rotation axis AX of the propeller 101. That is, the duct 2 is in the form of a cylinder (return shape). In the following description, the surface of the duct 2 facing the rotation axis AX at least at a part around the rotation axis AX of the propeller 101 is appropriately referred to as the inner surface of the duct 2 and the duct 2 The surface of the duct 2 facing the inner opposite side of the duct 2 is appropriately referred to as the outer surface of the duct 2.

The duct (2) has a front end (21) and a rear end (22). The front end portion (21) is disposed forward of the rear end portion (22). The front end portion 21 defines an inflow port 4 through which fluid (seawater or the like) flows. The rear end 22 is opposed to the propeller 101. The rear end 22 defines an outlet 5 through which the fluid flows out. In this embodiment, the size of the inlet 4 and the size of the outlet 5 are different. In the present embodiment, the outlet 5 is smaller than the inlet 4. In the present embodiment, the shape of the inlet 4 differs from the shape of the outlet 5.

As shown in Figs. 2 and 3, the inner surface of the duct 2 at the upper end of the rear end portion 22 is projected toward the rotation axis AX. That is, the inner surface of the duct 2 at the upper end of the rear end portion 22 has the convex portion 22T protruding inward. On the other hand, the inner surface of the duct 2 at the upper end of the front end portion 21 is not projected toward the rotation axis AX.

The outline of the front end portion 21 and the outline of the rear end portion 22 are symmetrical with respect to the transverse direction. That is, with respect to the reference line (symmetry axis) SR passing through the rotation axis AX and parallel to the vertical direction, the outline of the front end portion 21 and the outline of the rear end portion 22 are line symmetry.

4 is a sectional view showing an example of the duct 2 according to the present embodiment. 5 is a diagram showing an example of the outline of the front end portion 21 and the outline of the rear end portion 22. Fig. Fig. 5 shows one contour with respect to the axis of symmetry SR.

As shown in Fig. 4, the cross section of the duct 2 has a wing shape. The wing shape of the duct 2 has an external shape in which lift can be efficiently obtained by interaction with the fluid. The blade (sectional shape) of the duct 2 has a shape gradually tapering from the front edge toward the rear edge. In the present embodiment, the wing-shaped outer surface of the duct 2 has a straight shape or a convex shape or a concave shape that is smaller than the convex degree of the inner surface. The inner surface of the blade-like shape of the duct 2 has a convex curved surface shape on the inner side (on the rotary shaft AX side). The leading edge 23 of the leading edge of the blade 2 and the trailing edge 24 of the trailing edge of the blade 2 and the chord line 25 connecting the leading edge 23 and the trailing edge 24 And a center line 26 obtained by sequentially connecting the midpoints of the upper and lower surfaces of the wing-like shape. The front end portion 21 includes a leading edge 23 of a wing shape. The rear end 22 includes a wing-type trailing edge 24.

The duct 2 is arranged so that the distance between the rotary shaft AX and the leading edge 23 is larger than the distance between the rotary shaft AX and the trailing edge 24 in the radial direction.

At least part of the water flows along the inner surface of the duct 2 through the leading edge 23 of the duct 2 when the ship advances the water (marine). By Bernoulli's theorem, the inner surface of the duct 2 at the front end portion 21 becomes negative pressure, and lift is generated. The propulsive force is generated by the axial component of the lift (the propulsive force generated by the duct 2). Further, since the output of the power source for operating the propeller 101 is suppressed by the propulsive force generated by the duct 2, an energy saving effect is obtained.

In the present embodiment, the angle? Formed by the winged chord line 25 of the duct 2 and the line parallel to the rotation axis AX of the propeller 101 is appropriately referred to as an arrangement angle? .

In the present embodiment, the distance R between the midpoint 25M of the chord line 25 and the rotation axis AX of the propeller 101 with respect to the radial direction of the propeller 101 with respect to the rotation axis AX, Is appropriately referred to as a radial position (R).

In the present embodiment, the angle (placement angle)? Formed by the wing-like chord line 25 and the line parallel to the rotation axis AX of the propeller 101 and the midpoint 25M of the chord line 25, (Radial position) R between the rotation axis AX of the propeller 101 and the rotation axis AX of the propeller 101 is smaller than the distance between the first portion of the duct 2 and the duct 2 different from the first portion in the circumferential direction of the rotation axis AX. Lt; / RTI > That is, in this embodiment, the arrangement angle phi and the radial position R are different in each of plural portions of the duct 2 in the circumferential direction of the rotary shaft AX.

The upper end placement angle phi of the duct 2 disposed directly above the rotary shaft AX is determined by the side end placement angle phi of the duct 2 disposed immediately adjacent to the rotary shaft AX, Lt; / RTI > In the present embodiment, the shape of the duct 2 is determined so that the arrangement angle? Gradually decreases from the upper end (referred to as 0 deg) of the duct 2 toward the side end (referred to as 90 deg) with respect to the circumferential direction have.

In the present embodiment, the radial position R of the upper end of the duct 2 disposed immediately above the rotary shaft AX is equal to the radius of the side end of the duct 2 disposed immediately adjacent to the rotary shaft AX Is smaller than the position (R). In the present embodiment, the shape of the duct 2 is determined so that the radial position R gradually increases from the upper end (referred to as 0 deg) of the duct 2 toward the side end (referred to as 90 deg) with respect to the circumferential direction have.

More specifically, with respect to the circumferential direction, the radial position R at 0 deg to 10 deg represents the minimum value, and the radial position R gradually increases from 10 deg to 90 deg. In addition, when the diameter (outer diameter) of the propeller 101 is Rp, the minimum value of the radial position R may be 0.7Rp or less. The maximum value of the radial position R is set to Rp or less. The difference between the minimum value and the minimum value of the radial position R may be set to 0.5Rp or less.

With respect to the circumferential direction, the placement angle (?) At 0 deg to 10 deg represents the maximum value, and the placement angle (?) Gradually decreases from 10 deg to 90 deg. The minimum value of the placement angle (?) Is determined to be 0 degree or more.

2 and 3, a duct 2 having a convex portion 22T on the inner surface of the rear end portion 22 of the duct 2 and having a long length in the transverse direction is obtained.

The velocity component of the flow of the fluid (seawater) in the stern 100B (in front of the propeller 101) exists not only in the axial direction, but also in the circumferential direction and the radial direction. The flow field of the fluid flowing into the duct 2 through the inlet 4 is not uniform. Therefore, the arrangement angle phi and the radial position R of the duct 2 influence the driving force generated by the duct 2. According to the inventor's discovery, it has been found that the propulsive force of the duct 2 can not be sufficiently obtained if the arrangement angle phi and the radial position R of the duct 2 are constant with respect to the circumferential direction.

Therefore, in the present embodiment, the shape of the duct 2 is set such that the arrangement angle phi and the radial position R are different in each of a plurality of portions of the duct 2 in the circumferential direction of the rotary shaft AX . Thereby, the propulsive force generated by the duct 2 can be maximized, and a greater energy saving effect can be obtained.

For example, in the non-selected line, the dihedral angle at the position of 0 deg (upper end position) with respect to the circumferential direction is large, and the diopter angle at the position of 90 deg (side end position) tends to be small. At a position of 0 deg relative to the circumferential direction, the smaller the radial position R, the larger the flow velocity, and at the 90 deg position, the larger the radial position R, the greater the flow velocity.

The arrangement angle phi of the upper end portion of the duct 2 is made larger than the arrangement angle phi of the side end portion of the duct 2 and the radial position R of the upper end portion of the duct 2 2) and the radial position R of the side end portion of the duct 2, the propulsion force of the duct 2 estimated by the following equations (1), (2), and (3) can be increased.

L = 1/2 · Cl (α) · ρ · S · V2 ... (One)

D = 1/2 Cd (?)? S? V2 ... (2)

F = L? Sin? -D? Cos? (3)

L: lift

D: Drag

F: propulsive force (forward component of the resultant force)

Cl: lift coefficient (depending on blade performance, depending on angle of attack α)

Cd: drag coefficient (depending on blade performance, depending on angle of attack α)

ρ: fluid specific gravity

S: Duct surface area (by radial position)

V: Flow rate (synthetic flow rate in axial direction and radial direction)

θ: Orientation angle (angle between axial flow velocity and radial flow velocity)

Next, the stay 3 will be described. As shown in Figs. 1, 2, and 3, the stay 3 has a front end portion 31 and a rear end portion 32. As shown in Fig. The front end (31) is disposed forward of the rear end (32). The rear end portion (32) faces the propeller (101).

The stay 3 connects the duct 2 and the stern tube 104 of the hull 100. The stay 3 has an inner end 38 connected to the outer surface of the stern tube 104 and an outer end 39 connected to the inner surface of the duct 2. The outer end portion 39 is disposed outside the inner end portion 38 with respect to the radial direction of the propeller 101 with respect to the rotation axis AX.

The duct device (1) has a pair of stays (3). In the following description, one of the stays 3 is appropriately referred to as a first stay 301 and the other stays 3 are referred to as a second stay 302 as appropriate. The first stay 301 is disposed on one side of the rotation axis AX with respect to the transverse direction. The second stay 302 is disposed on the other side of the rotation axis AX with respect to the transverse direction. In the present embodiment, the first stay 301 and the second stay 302 are arranged substantially parallel to the horizontal plane.

6 shows a sectional view of the stay 3 according to the present embodiment. As shown in Fig. 6, the end surface of the stay 3 has a wing shape. The wing shape of the stay 3 has an external shape in which lift can be efficiently obtained by interaction with the fluid. The blade (sectional shape) of the stay 3 has a shape gradually tapering from the front edge to the rear edge. In the present embodiment, the upper surface of the wing shape of the stay 3 is a linear shape or a convex shape or a concave shape having a convex degree or less on the inner surface. The bottom surface of the blade 3 of the stay 3 has a curved surface convex downward. The leading edge 33 of the blade at the front end of the blade 3 and the trailing edge 34 at the trailing end of the blade 3 and the chord line 35 connecting the leading edge 33 and the trailing edge 34 And a center line 36 obtained by sequentially connecting the midpoints of the upper and lower surfaces of the wing-like shape. The front end portion (31) includes a leading edge (33) of a wing shape. The rear end portion 32 includes a wing-type trailing edge 34.

In the present embodiment, the stay 3 is arranged such that the winged chord line 35 is inclined. In the present embodiment, the stay 3 is inclined such that the leading edge 33 of the winged chord line 35 is disposed above the trailing edge 34.

The stay 3 may be arranged so that the chord line 35 is inclined with respect to the horizontal plane. The stay 3 may be arranged such that the chord line 35 is inclined with respect to the waterline. The waterline includes at least one of the planned waterline and the designed waterline. The stay 3 may be inclined such that the leading edge 33 is spaced apart from the trailing edge 34 at a predetermined angle relative to a predetermined surface including the rotating axis AX. The predetermined surface including the rotation axis AX may be a horizontal surface or an inclined surface inclined to the horizontal surface.

The stay 3 is arranged so that the angle? Formed by the horizontal plane and the chord line 35 is between 0 and 10 degrees inclusive do.

At least part of the water flows along the inner surface of the stay 3 through the leading edge 33 of the stay 3 when the ship advances the water (marine). By the Bernoulli theorem, the lower surface of the stay 3 at the front end portion 31 becomes a negative pressure, and lift is generated. A large thrust force is generated by the axial component of the lift (the thrust generated by the stay 3) and the propulsive force of the propeller 101. [ Also, since the output of the power source for operating the propeller 101 is suppressed by the propulsive force generated by the stay 3, an energy saving effect is obtained.

As described above, according to the present embodiment, the duct 2 is formed such that the arrangement angle? And the radial position R are different in a plurality of portions in the circumferential direction, so that the energy saving effect .

In addition, in the present embodiment, since the end surface of the stay 3 is a wing shape, not only the duct 2 but also the stay 3 generates thrust. Thereby, a higher energy saving effect can be obtained.

In the present embodiment, the outer end 39 of the stay 3 is connected to the return duct 2. As a result, the occurrence of tip end loss is suppressed. A swirling occurs in at least one of the end of the stay 3 and the end of the duct 2 when the outer end 39 of the stay 3 is not connected to the duct 2. As a result, There is a possibility that the effect can not be sufficiently exercised. In the present embodiment, since the stay 3 and the duct 2 are connected to each other, the occurrence of eddies is suppressed. As a result, a high energy saving effect can be obtained.

≪ Second Embodiment >

The second embodiment will be described. In the following description, constituent elements which are the same as or equivalent to those of the above-described embodiment are denoted by the same reference numerals, and the description thereof will be simplified or omitted.

Fig. 7 shows an example of the stay 3B of the duct apparatus 1B according to the present embodiment. The end surface of the stay 3B has a wing shape. In this embodiment, the stay 3B is a symmetrical wing having a wing-like top surface shape and a bottom surface shape that are symmetrical. Also, the stay 3B may be an asymmetric blade whose top surface and bottom surface shape are asymmetric.

The stay 3B has an inner end 38 connected to the hull 100 and an outer end 38 disposed outside the inner end 38 with respect to the radial direction of the propeller 100 about the rotation axis AX, And an outer end portion 39 connected to the end portion.

In the present embodiment, the angle? Formed by the winged chord line 35 of the stay 3B and the horizontal plane differs in each of a plurality of portions of the stay 3B with respect to the radiation direction. The angle? Of the wing-like chord line 35 of the stay 3B at the inner end portion 38 and the angle? Of the wing-like chord of the stay 3B at the outer end portion 39 The angle? Of the chord line 35 is different. The stay 3B is twisted such that the angle? Gradually changes from the inner end portion 38 toward the outer end portion 39. [

In this embodiment, the chord line 35 at the inner end portion 38 of the stay 3B is inclined so that the wing-like leading edge 33 is disposed above the trailing edge 34, The chord line 39 at the outer end portion 39 of the front end portion 39 is inclined so that the wing-shaped leading edge 33 is disposed below the trailing edge 34. [

The flow field of the fluid around the duct 2 and the stay 3B differs with respect to the radial direction with respect to the rotational axis AX of the propeller 101. [ For example, fluid (sea water) flows downward on the inner side with respect to the radial direction, and fluid (sea water) flows downward on the outer side with respect to the radial direction. Therefore, the inclination angle [gamma] of the stay 3B affects the driving force generated by the stay 3B. According to the inventor's discovery, by changing the angle (inclination angle) of the chord line 35 of the stay 3B with respect to the radial direction (inclination angle of the stay 3B) with respect to the radiating direction, Can be further improved.

Therefore, in the present embodiment, the shape of the stay 3B is determined such that the inclination angle? Is different in each of plural portions of the stay 3B with respect to the radial direction with respect to the rotation axis AX. Thereby, the thrust generated by the stay 3B can be maximized, and a greater energy saving effect can be obtained.

This makes it possible to increase the thrust force of the stay 3B evaluated by the following expressions (4), (5), and (6) by adjusting the inclination angle y of the stay 3B.

L = 1/2 · Cl (α) · ρ · S · V2 ... (4)

D = 1/2 Cd (?)? S? V2 ... (5)

F = L? Sin? -D? Cos? (6)

L: lift

D: Drag

F: propulsive force (forward component of the resultant force)

Cl: lift coefficient (depending on wing performance, depends on angle of attack α)

Cd: drag coefficient (depending on blade performance, depending on angle of attack α)

ρ: fluid specific gravity

S: Stay surface area

V: Flow velocity (synthetic flow velocity in the direction crossing the stay and in the mainstream direction)

θ is the diagonal angle (the angle between the directional flow velocity across the stay and the mainstream flow velocity)

≪ Third Embodiment >

The third embodiment will be described. In the following description, constituent elements which are the same as or equivalent to those of the above-described embodiment are denoted by the same reference numerals, and the description thereof will be simplified or omitted.

Fig. 8 shows an example of the duct device 1C according to the present embodiment. 8, the stay 3 includes a first stay 301 and a second stay 302 disposed above the rotation axis AX of the propeller 101. The first stay 301 and the second stay 302, The angle formed by the first stay 301 and the second stay 302 with respect to the circumferential direction of the rotary shaft AX is smaller than 90 degrees. The outer end portion 39 connected to the duct 2 is disposed above the inner end portion 38 connected to the hull 100 in this embodiment. Also in this embodiment, an energy saving effect can be obtained.

≪ Fourth Embodiment &

The fourth embodiment will be described. In the following description, constituent elements which are the same as or equivalent to those of the above-described embodiment are denoted by the same reference numerals, and the description thereof will be simplified or omitted.

Fig. 9 shows an example of the duct device 1D according to the present embodiment. 9, the duct device 1D has a duct 2D and a stay 3D for connecting at least a part of the duct 2D and the hull 100. As shown in Fig. The surface of the connecting portion of the duct 2D and the stay 3D includes a curved surface. That is, in the present embodiment, the corner portion is not provided at the connection portion between the duct 2D and the stay 3D.

According to the present embodiment, it is possible to drastically reduce the tip loss. Also in this embodiment, the thrust generated by the stay 3D assists the propulsive force generated by the duct 2D.

1 duct device
2 ducts
3 stays
4 inlet
5 outlet
21 Front end
22 rear end
22T convex portion
23 leading
24 trailing
25 kyonghyun line
31 front end portion
32 rear end
33 leading
34
35 Kyo Hyun Line
38 inner end
39 outer end
100 hull
101 Propeller
AX rotary shaft

Claims (10)

A duct disposed at least in a part around the rotation axis of the propeller in front of a propeller provided at the stern of the hull,
A stays for connecting at least part of the duct to the hull,
And,
The cross section of the duct is a wing-
The angle formed by the wing-like chord line and a line parallel to the rotation axis and the center point of the chord line and the distance between the rotation axis and the first part of the duct are different from the first part in the circumferential direction of the rotation axis The second portion of the duct being different,
Wherein at least a part of the duct is disposed above the rotary shaft,
Wherein the first portion includes an upper end of the duct,
Wherein the second portion includes a side end portion of the duct,
Wherein the angle of the first portion is greater than the angle of the second portion,
Wherein the distance of the first portion is less than the distance of the second portion,
Wherein said duct has a front end defining an inlet and a rear end opposite to said propeller and defining an outlet having a different size and shape from said inlet,
Wherein the outlet is smaller than the inlet,
The inner surface of the upper end of the rear end portion protrudes toward the rotation shaft,
Wherein the inner surface of the upper end of the front end portion does not protrude toward the rotating shaft. delete delete The method according to claim 1,
Wherein a cross section of the stay is a wing-shaped duct device. A duct disposed at least in a part around the rotation axis of the propeller in front of a propeller provided at the stern of the hull,
A stays for connecting at least part of the duct to the hull,
And,
The cross section of the stay is a wing-
The stay has an inner end connected to the hull and an outer end disposed outside the inner end with respect to the radial direction of the propeller and connected to the duct,
Wherein an angle formed by the wing-like chord line and the horizontal plane differs between a third portion of the stay and a fourth portion of the stay different from the third portion with respect to the radial direction,
Wherein the stay is twisted such that the angle gradually changes from the inner end toward the outer end. The method of claim 5,
Wherein the stay is inclined such that the leading edge of the winged chord line is disposed above the trailing edge. The method of claim 4,
The stay has an inner end connected to the hull and an outer end disposed outside the inner end with respect to the radial direction of the propeller and connected to the duct,
Wherein an angle between the wing-like chord line and the horizontal plane is different in a third part of the stay and in a fourth part of the stay different from the third part with respect to the radial direction. A duct disposed at least in a part around the rotation axis of the propeller in front of a propeller provided at the stern of the hull,
A stays for connecting at least part of the duct to the hull,
And,
The cross section of the stay is a wing-
The stay has an inner end connected to the hull and an outer end disposed outside the inner end with respect to the radial direction of the propeller and connected to the duct,
Wherein an angle formed by the wing-like chord line and the horizontal plane differs between a third portion of the stay and a fourth portion of the stay different from the third portion with respect to the radial direction,
The chord line at the inner end of the stay is inclined so that the leading edge of the wing shape is disposed above the trailing edge,
Wherein the chord line at the outer end of the stay is inclined so that the leading edge of the wing shape is disposed below the trailing edge. The method according to any one of claims 1, 5, 6, 7, and 8,
Wherein the stay comprises a first stay and a second stay disposed above a rotational axis of the propeller,
Wherein the angle between the first stay and the second stay with respect to the circumferential direction of the rotating shaft is less than 90 degrees. The method according to any one of claims 1, 5, 6, 7, and 8,
Wherein the duct is disposed so as to surround a part of the rotary shaft above the rotary shaft of the propeller.

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