JP6021678B2 - Duct device and ship using the same - Google Patents

Description

  The present invention relates to a duct device that changes a water flow flowing into a propeller at a stern part of a ship.

  As a device for improving the propulsion efficiency of a ship, a technique of arranging a duct in front of a propeller is known. Patent document 1 shows an example of such a technique.

JP 2008-137462 A

  FIG. 1 shows an example of a duct arranged in front of the propeller as a reference technique. A propeller 103 and a rudder 104 are disposed on the stern portion 102 of the ship 101. A duct 105 is disposed in front of the propeller 103. The duct 105 has an annular shape that is generally centered on the rotation axis of the propeller 103. The end of the duct 105 in the bow direction has a larger diameter than the end in the stern direction.

  FIG. 2 is an enlarged view of the duct 105 in the region 106 of FIG. A cross section perpendicular to the circumferential direction of the duct 105 has a wing shape. The leading edge of the wing is located on the bow side and the trailing edge is located on the stern side. The inner peripheral side of the duct 105, that is, the side close to the rotation axis of the propeller is the negative pressure surface 107, and the outer peripheral side is the positive pressure surface. The duct 105 is formed such that the chord line is inclined inward toward the stern side at an angle θ with respect to the rotation axis of the propeller 103.

  In FIG. 2, the water flow in the stern portion 102 flows into the duct 105 at an angle Ψ = α + θ with respect to the rotation axis of the propeller 103. α is the angle of attack of the water flow with respect to the duct 105 having the blade cross-sectional shape. By this water flow, the duct 105 generates a lift f101 perpendicular to the flow and a drag f102 parallel to the flow. A component in the bow direction of the resultant force f103 of the lift force f101 and the drag force f102 becomes a propulsive force that acts on the duct 105.

  In this way, the duct 105 can generate a driving force. In the technology of providing a duct in front of the propeller, it is desired to further improve the propulsion efficiency.

  In one embodiment of the present invention, the duct device is disposed in front of the propeller at the stern portion of the ship. The duct device includes a duct body. The duct body is located on the rear side of the ship and has a trailing edge that draws an arc with the rotation axis of the propeller inside, and a duct that is on the front side of the ship and draws an arc with the rotation axis on the inside and perpendicular to the rotation axis. And a leading edge having a directional contour shape larger than the trailing edge. The cross section of the plane including the rotation axis of the duct body has a wing shape, and the angle formed by the chord line of the cross section and the extending direction of the rotation axis is the angle in the circumferential direction around the rotation axis close to the vertical line The bigger the position.

  According to the present invention, propulsion efficiency can be further improved in the technique of providing a duct in front of the propeller.

FIG. 1 is a side view of a stern part in the reference technique. FIG. 2 shows the cross-sectional shape of the duct. FIG. 3 is a side view of the stern part. FIG. 4 is a perspective view of the duct body. FIG. 5 is a front view of the duct body. FIG. 6 shows the duct body and the water flow in the BB ′ cross section of FIG. FIG. 7 shows a duct body and a water flow in the CC ′ cross section of FIG. 5. FIG. 8 shows the relationship between the circumferential angle φ around the rotation axis C1 and the flow direction angle Ψ. FIG. 9 shows the flow velocity distribution viewed from the stern side. FIG. 10 shows a cross-sectional shape of the duct body. FIG. 11 is a front view of the duct device. FIG. 12 shows the shape and attachment angle of the reaction fin.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 3 is a side view showing a stern part of a ship provided with the duct device 5 according to the first embodiment of the present invention. A propeller 3 is installed on the stern portion 2 of the ship 1 and a rudder 4 is installed on the rear side (stern side). The propeller 3 includes a plurality of wings arranged in the circumferential direction, and rotates about a rotation axis C1 that extends in a ship length direction that generally connects the bow and stern.

  A duct device 5 is attached to the front (the bow side) of the propeller 3 in the stern part 2. The duct device 5 has a front edge 6 and a rear edge 7 that draw an arc with the rotation axis C1 as the inner side. The contour shape of the rear edge 7 in the cross section perpendicular to the rotation axis C1 (projection shape in the direction parallel to the rotation axis C1) is smaller than the front edge 6.

  FIG. 4 shows a schematic shape of the duct main body 9 having a function of changing the water flow in the duct device 5. A virtual cone C2 having a predetermined point (x = x0) as a vertex and a center line in the x-axis direction is drawn with the rotation axis C1 of the propeller 3 as the center. For the cone C2, the yz cross section at the first distance x = x1 from the apex is shown as a circle C3, and the yz cross section at the second distance x = x2 (x2> x1) is shown as a circle C4.

  Further, on the plane of x = x2, a curve extending upward from the circle C4 is set as the front edge 6 of the duct body 9 within the range of the angle φ from the vertical line V passing through the rotation axis C1 to the left and right. . The smaller the angle from the vertical line V, the larger the length of the portion that protrudes from the circle C4. Such a shape can be realized, for example, by forming the leading edge 6 in a parabola.

  The shape of a truncated cone is formed by the surface connecting the circle C3, the circle C4, and the C3 and C4 of the cone C2. In this truncated cone, the shape obtained by replacing C4 with the front edge 6 at a location where a region within a predetermined angle φ is cut from the upper vertical line V around the rotation axis C1 is an outline of the duct body 9. Show shape. The duct body 9 is bilaterally symmetric about a vertical plane including the rotation axis C1 of the propeller 3.

  The front edge 6 of the duct body 9 draws a convex curve from the vertical line V to the left and right sides of the rotation axis C1 toward the outer periphery side in the range of φ. Although the value of φ is not particularly limited, it is desirable that φ be 90 degrees or less because the water flow flowing into the upper half of the propeller 3 can easily obtain the propulsive force by the duct device 5. The rear edge 7 of the duct body 9 draws an arc on a circle C3. In the example of FIG. 4, the angle of the arc is the same as that of the leading edge 6, but may be an angle different from that of the leading edge 6. The trailing edge 7 does not need to be a complete arc, and may be an arc that is a deformed arc, such as a parabola.

  In the present embodiment, the duct body 9 has a shape with a greater inclination as it extends upward. More precisely, the cross section B by the plane P including the rotation axis C1 of the duct body 9 has a blade shape with the inner peripheral side as the negative pressure side. The angle α formed by the chord line CH of the cross section B and the extending direction of the rotation axis C1 is larger as the circumferential angle φ around the rotation axis C1 is closer to the vertical line V. With such a shape, an efficient propulsive force can be obtained according to the flow velocity distribution of the stern portion 2. The reason will be described below.

  FIG. 5 is a front view showing the duct device 5 as seen from the bow direction. FIG. 4 is a view of the inside of the duct body 9 viewed from the front in the AA ′ cross section shown in FIG. 3. The duct device 5 includes a support portion 10, and the duct body 9 is fixed to, for example, the bossing 8 of the stern portion 2 by the support portion 10.

  FIG. 6 shows the duct main body 9 and the water flow in the BB ′ cross section of FIG. FIG. 12 shows the duct main body 9 and the water flow in the CC ′ cross section of FIG. 10. In the BB ′ cross section shown in FIG. 11, the inclination angle of the duct body 9 (more precisely, the inclination angle in the plane including the rotation axis C1 with respect to the extending direction (x-axis direction) of the rotation axis C1) θ1 is large. . In this region, a water flow near the rotation axis C <b> 1 flows into the rear edge 7 of the duct body 9. Since the water flow in this region has a large component in the radial direction, the duct body 9 can generate a larger propulsive force when the duct body 9 has a large inclination.

  On the other hand, in the CC ′ cross section shown in FIG. 7, the inclination angle of the duct body 9 (more precisely, the inclination angle in the plane including the rotation axis C1 with respect to the extending direction of the rotation axis C1) θ2 is small. The water flow in this region has a larger component in the direction of the rotation axis C1 than the section BB ′. For this reason, since the inclination of the duct body 9 with respect to the direction of the rotation axis C1 is small, α <0 is not established, and the duct body 9 can generate thrust in the forward direction.

  In a duct having a typical wing shape, a large propulsive force can be obtained when the angle of attack α of the water flow flowing into the duct body 9 is around 0 degrees to 20 degrees. Therefore, the shape of the duct body 9 is designed as follows. (1) The flow velocity distribution of the water flow ahead of the propeller 3 in the stern part 2 is obtained. (2) Based on the flow velocity distribution, the inclination of the duct body 9 in each circumferential direction (α1 in FIG. 11, α2 in FIG. 12) approaches 0 to 20 degrees so that the angle of attack (α1 in FIG. 11 and α2 in FIG. 12) approaches 0 degrees to 20 degrees. Design θ1, θ2). FIG. 8 shows the relationship between the circumferential angle φ around the rotation axis C1 and the flow direction angle Ψ. In the region where φ is small, the flow direction angle Ψ is large, so that the inclination θ of the duct body 9 is designed to be large.

  In order to obtain the effects described above, shapes other than the duct main body 9 of FIG. 4 are also conceivable. For example, a modified example in which the shape of the leading edge 6 is an arc and the shape of the trailing edge 7 is a curve (for example, a parabola) whose height is lower than the trailing edge side circle C3 as φ is smaller is conceivable. Even with such a shape, since the inclination of the duct body 9 is larger in the region where φ is smaller as shown in FIG.

  Next, a preferred range of the angle φ shown in FIG. 4 will be described. In FIG. 9, the figure which looked at the flow-velocity distribution of the water flow which flows into the propeller 3 from back (stern direction) is shown. As shown in this example, in the region 11 where the angle from the upward vertical line V is 45 degrees or more, the radial component of the flow velocity is small. On the other hand, in the region where the angle from the vertical line V is 45 degrees or less, the radial component of the flow velocity is large. The duct body 9 generates a larger propulsive force in a region where the radial component of the flow velocity is large. As shown in FIG. 8, in the region where the leading edge 6 of the duct body 9 exceeds an angle of 45 degrees from the vertical line V, the flow direction angle is often less than 10 °, and the thrust obtained at this flow direction angle is small. . Therefore, it is desirable that the duct body 9 is formed so that the front edge 6 supplements the water flow in a region within an angle of 45 degrees from the vertical line V.

  Therefore, for example, if the leading edge 6 has a fan shape of φ = 45 degrees or a duct body 9 having a fan shape of φ = 50 degrees in order to reliably supplement the water flow at a position of 45 degrees, sufficient thrust is generated. be able to. Therefore, in a preferred embodiment, the duct body 9 has an angle in the circumferential direction centered on the vertical line V passing through the rotation axis C1 of the propeller 3 within 50 degrees. Furthermore, it is preferable that φ is set within 50 degrees because the duct body 9 is small and light, and the flow flowing into the propeller 3 is not hindered in the outer region.

  Next, the radial size of the duct body 9 will be described. The contour shape of the trailing edge 7 in the cross section perpendicular to the rotation axis C1 falls within the range of 0.2R to 0.5 when the radius of the rotation surface C5 of the propeller 3 is R. More specifically, as shown in FIG. 5, when the radius of the trailing edge 7 is r1, 0.2R ≦ r1 ≦ 0.5R. When the trailing edge 7 is not a complete arc, it is preferable that the entire trailing edge 7 is within a circle of 0.5R or less centered on the rotation axis C1. Hereinafter, advantages obtained by such a radius r1 will be described.

  FIG. 10 shows a cross-sectional shape of the duct body 9. The cross section perpendicular to the circumferential direction of the duct body 9 has a wing shape at an arbitrary angle in the circumferential direction. The inner peripheral side of the duct body 9, that is, the side facing the rotation axis C1 is a negative pressure surface, and the outer peripheral side is a positive pressure surface.

  When the ship 1 is sailing forward, a water flow is relatively generated in the hull. In the stern part 2, the water flow at the position of the duct device 5 is changed by the duct body 9. Inside the duct body 9, the water flow is accelerated in the direction of the rotation axis C <b> 1 by the duct body 9, and the water flow f <b> 1 has a fast axial flow velocity. On the other hand, generally, the water flow on the upper side of the propeller 3 has a low axial flow velocity. A water flow f2 having such a slow axial flow velocity flows into the outside of the duct body 9.

  The general propeller 3 works most efficiently in a region slightly outside the center in the radial direction, for example, in the vicinity of 0.7R. In this embodiment, in this region, since the water flow f2 having a slow axial flow rate flows in, the propeller 3 generates a propulsive force with high efficiency.

  On the other hand, in a region inside the duct body 9, a propulsive force (a component in the bow direction of lift) is generated in the duct body 9 by the water flow. Although the axial flow velocity of the water flow f1 is increased by the duct body 9, the propulsion efficiency of the propeller 3 in the region of r1 ≦ 0.5R is relatively small from the beginning, so that a reduction in propulsive force of the propeller 3 is suppressed to a small level. In order to obtain an effective driving force by the duct body 9, it is desirable that r1 ≧ 0.2R.

  As described above, in the region where the distance r from C1 is about 0.7R, the duct device 5 does not obstruct the flow and the propeller 3 generates a high driving force, and the efficiency of the propeller 3 is small. Propulsive force can be generated by the duct device 5 in the region. Therefore, high propulsive force can be obtained by combining the propeller 3 and the duct device 5.

  FIG. 11 is a front view of the duct device 5 according to the second embodiment of the present invention. The duct device 5a in the present embodiment includes the same duct body 9 as in the first embodiment. The duct device 5a according to the second embodiment further includes a reaction fin 12 composed of at least one blade (two blades in the example of FIG. 11). The reaction fin 12 improves the efficiency of the propeller 3 by giving the flow velocity distribution in the stern portion 2 a change in the direction opposite to the rotation direction of the propeller 3.

A known reaction fin design can be applied to the contour shape and the mounting angle of the reaction fin 12. FIG. 12 shows an example. The cross section of the reaction fin 12 attached to the right side when viewed from the stern direction is shown in the clockwise propeller 3 (providing forward thrust to the hull 1 when rotating clockwise when viewed from the stern direction). In this position, reaction fin 12 is attached to the front of the propeller 3 with a downward inclination angle theta _R toward the bow direction. The negative pressure surface 12a is arranged in the rotational direction of the propeller 3, that is, in the clockwise rotation direction with respect to the positive pressure surface 12b. Such reaction fins 12 can improve the efficiency of the propeller 3.

  In FIG. 11, the reaction fin 12 is supported by the duct body 9 at the end of the base (side close to the rotation axis C <b> 1). The tip extends, for example, to 1.1R, where R is the radius of the rotating surface C5 of the propeller 3.

  The reaction fin 12 is most effective in the vicinity of the radius 0.7R where the efficiency of the propeller 3 is high. On the other hand, the effect is small near the radius of 0.5 R or less, and the efficiency of the propeller 3 may be lowered. In the present embodiment, the reaction fin 12 is not disposed near the base near the propeller 3 by being supported by the duct body 9, and can be disposed only in the region having a radius of 0.5 or more where the effect is the highest. Become.

  In the known reaction fin supported by the bossing or the like, a configuration in which the influence on the water flow is reduced by twisting the angle of the fin in the vicinity of the root where the effect is low can be considered. However, in the present embodiment, since the reaction fins 12 do not need to be arranged near the roots, the reaction fins 12 can be formed of members having a shape that is easy to process without twisting.

DESCRIPTION OF SYMBOLS 1 Hull 2 Stern part 3 Propeller 4 Rudder 5 Duct apparatus 6 Front edge 7 Rear edge 8 Propeller shaft 8 Bossing 9 Duct body 10 Support part 11 Area 12 Reaction fin 12a Negative pressure surface 12b Positive pressure surface 101 Hull 102 Stern portion 103 Propeller 104 Rudder 105 Duct device 106 Region 107 Negative pressure surface 108 Positive pressure surface B Cross section C1 Rotating shaft C2 Conical surface C3 Front edge side circle C4 Rear edge side circle C5 Rotation surface CH Chord line f1, f2 Water flow f101 Lift force f102 Drag f103 Propulsion force P Plane V Vertical line

Claims (8)

A duct device disposed in front of a propeller at a stern part of a ship,
The duct device comprises a duct body,
The duct body is
A rear edge that is located on the rear side of the ship and draws an arc with the rotation axis of the propeller inside,
The front side of the ship is located in an arc with the rotation axis on the inside, and has a front edge whose contour shape in a direction perpendicular to the rotation axis is larger than the rear edge,
A section of the duct body including a plane including the rotation axis has a wing shape, and an angle formed by a chord line of the section and an extending direction of the rotation axis is an angle in a circumferential direction around the rotation axis. but rather the size as a position close to the vertical line,
The shape of the front edge in a cross section perpendicular to the rotation axis is more than a virtual circle centered on a point on the rotation axis within a predetermined angle range from the vertical line passing through the rotation axis. It is a curved shape that projects upward,
The said curve shape is a duct apparatus with the overhang | projection length from the said virtual circle being large, so that the angle from the said perpendicular line is small . The duct device according to claim 1, wherein a cross section of the duct main body in a plane including the rotation shaft has a blade shape having a suction surface on the rotation shaft side. 3. The duct device according to claim 1, wherein the rear edge has a contour shape in a direction perpendicular to the rotation axis within a region smaller than 0.5 R, where R is a radius of the propeller. A duct device disposed in front of a propeller at a stern part of a ship,
The duct device comprises a duct body,
The duct body is
A rear edge that is located on the rear side of the ship and draws an arc with the rotation axis of the propeller inside,
The front side of the ship is located in an arc with the rotation axis on the inside, and has a front edge whose contour shape in a direction perpendicular to the rotation axis is larger than the rear edge,
A section of the duct body including a plane including the rotation axis has a wing shape, and an angle formed by a chord line of the section and an extending direction of the rotation axis is an angle in a circumferential direction around the rotation axis. Is closer to the vertical line,
The duct body, the circumferential direction of the angle of the rotation axis from the upward vertical line that fit in the within 50 degrees
Da ECTS system. The duct device according to any one of claims 1 to 4, further comprising at least one reaction fin supported by the duct body and extending radially outward from the duct body.   A ship comprising the duct device according to any one of claims 1 to 5. The leading edge is in a plane perpendicular to the rotation axis
The duct apparatus according to any one of claims 1 to 5. A duct device disposed in front of a propeller at a stern part of a ship,
The duct device comprises a duct body,
The duct body is
A rear edge that is located on the rear side of the ship and draws an arc with the rotation axis of the propeller inside,
The front side of the ship is located in an arc with the rotation axis on the inside, and has a front edge whose contour shape in a direction perpendicular to the rotation axis is larger than the rear edge,
A section of the duct body including a plane including the rotation axis has a wing shape, and an angle formed by a chord line of the section and an extending direction of the rotation axis is an angle in a circumferential direction around the rotation axis. Is closer to the vertical line,
When the front edge is viewed from the bow direction along the rotation axis, the shape of the front edge intersects with an imaginary circle centered on a point on the rotation axis at two locations above the rotation axis. A curved shape having a curved shape including a portion protruding upward from the virtual circle;
The protruding portion has a longer protruding length from the virtual circle as the angle from the vertical line is smaller.
Duct device.

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