JP2014125200A - Duct device and ship using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid lowering of propulsion efficiency of a propeller, in a technology for providing a duct in front of the propeller.SOLUTION: A duct device 5 is arranged in front of a propeller 3 on a stern part 2 of a ship. The duct device includes a duct body. The duct body has: a rear edge 7 which is positioned on the rear side of the ship, and draws an arc positioning a revolving shaft C1 of the propeller inside, and in which a contour shape in the vertical direction to the revolving shaft is settled in a region of 0.5R or less, when the radius of the propeller is shown as R; and a front edge 6 which is positioned on the front side of the ship, and draws an arc positioning the revolving shaft inside, and in which the contour shape in the vertical direction to the revolving shaft is larger than that of the rear edge.

Description

  The present invention relates to a duct device that affects a water flow flowing into a propeller at the stern portion 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 is disposed on the stern portion 102 of the ship 101, and a rudder 104 is disposed behind the propeller 103. A duct 105 is disposed in front of the propeller 103 (in the bow direction). 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 108. The duct 105 is formed so that a chord line connecting the leading edge and the trailing edge of the wing shape is inclined toward the inner periphery side 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. However, the duct 105 has the effect of changing the direction of the water flow flowing into the propeller 103 and apparently accelerating in the axial direction. Since the propeller 103 is more efficient when the water flow speed is slower, if the water flow is accelerated in the axial direction of the propeller 103 by the duct 105, the efficiency of the propeller 103 may be reduced. Therefore, the addition of the duct 105 may not effectively improve the overall efficiency of the combined propeller 103 and duct 105.

  In the technique of providing a duct in front of the propeller, it is desired to avoid a decrease in propulsion efficiency of the propeller.

  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, draws an arc with the propeller axis inside, and the contour shape seen in the axial direction is within the region of 0.5R or less with the propeller radius being R, An arc that is located on the front side of the propeller and that has an axis that is the inner side of the axis of the propeller is drawn, and has a front edge that has a contour shape that is larger than the front edge.

  According to the present invention, in the technique of providing a duct in front of the propeller, it becomes possible to avoid a decrease in propulsion efficiency 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 shows the flow velocity distribution viewed from the stern side. FIG. 6 shows the relationship between the angle in the circumferential direction around the propeller axis and the flow direction angle. FIG. 7 is a front view of the duct device. FIG. 8 shows a cross-sectional shape of the duct body. FIG. 9 is a perspective view of the duct body. FIG. 10 is a front view of the duct body. FIG. 11 shows the duct body and water flow in the BB ′ cross section of FIG. FIG. 12 shows a duct main body and a water flow in the CC ′ cross section of FIG. 10. FIG. 13 is a front view of the duct device. FIG. 14 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 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 in front of the propeller 3 in the stern part 2. The duct device 5 has an arcuate front edge 6 and a rear edge 7 that draw an arc with the rotation axis C <b> 1 inside. The contour shape of the trailing edge 7 in the cross section perpendicular to the rotation axis C <b> 1 is smaller than the radius of the leading edge 6. When the radius of the rotation surface of the propeller 3 is R, the contour shape of the trailing edge 6 in the cross section perpendicular to the rotation axis C1 falls within the region of 0.2R to 0.5R.

  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.

  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, a portion obtained by cutting a region within a predetermined angle φ from the left and right of the vertical line V around the rotation axis C <b> 1 indicates the schematic shape of the duct body 9. The duct body 9 is bilaterally symmetric about a vertical plane including the rotation axis C1 of the propeller 3.

  The leading edge 6 of the duct body 9 draws an arc on a circle C4. The angle is φ from the vertical line V to the left and right around the rotation axis C1. 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 leading edge 6 and the trailing edge 7 do not have to be complete arcs, and may be arcs obtained by deforming arcs such as parabolas, for example.

  In FIG. 5, 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. FIG. 6 shows the distribution of the flow direction angle Ψ at each circumferential angle φ1. As shown in this example, in the region 11 above the rotation axis C1 and having an angle of 45 degrees or more from the vertical line V, 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. 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.

  FIG. 7 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.

  When the radius of the trailing edge 7 is r1 and the radius of the rotating surface C5 of the propeller 3 is R, 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. 8 shows a cross-sectional shape of the duct main 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 main body 9, the water flow is bent in the direction of the rotation axis C <b> 1 by the duct main body 9, and becomes a water flow f <b> 1 having a high 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 the region inside the duct body 9, a propulsive force (a component in the bow direction of the resultant force of lift and drag) 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 can be 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 present embodiment, when the distance in the radial direction from the shaft is r, the propeller 3 has a high propulsive force without disturbing the flow of the duct device 5 in the region of r = 0.7R. In the region where R ≦ 0.5 where the efficiency of the propeller 3 is small, propulsive force can be generated by the duct device 5. Therefore, high propulsive force can be obtained by combining the propeller 3 and the duct device 5.

  Next, a second embodiment of the present invention will be described. 9 and 10 are a perspective view and a front view showing a schematic shape of the duct main body 9a in the present embodiment. In contrast to the duct body 9 in the first embodiment forming part of the conical surface, in this embodiment, the duct body 9a has a shape with a greater inclination toward the top. As described below, according to such a shape, an efficient propulsive force can be obtained according to the flow velocity distribution of the stern portion 2.

  The shape of the duct main body 9a in the present embodiment will be described in more detail. A section B of the duct main body 9 along the plane P including the rotation axis C1 has a blade shape similar to that of the duct main body 9 shown in FIG. The angle θ formed by the chord line CH of the cross section and the extending direction (x-axis direction) of the rotation axis C1 is larger as the circumferential angle φ1 about the rotation axis C1 is closer to the vertical line V.

  9 and 10, the duct body 9a has a front edge 7a that forms a part of the front edge side circle C3, similarly to the duct body 9 in the first embodiment. On the other hand, the rear edge 6a of the duct main body 9a has a contour shifted from the rear edge side circle C4. That is, the smaller the angle φ1, the larger the shape of the rear edge side circle C4. Such a shape can be realized, for example, by forming the trailing edge 6a as a parabola.

  FIG. 11 shows the duct main body 9a and the water flow in the BB ′ cross section of FIG. FIG. 12 shows the duct body 9a and the water flow in the CC ′ cross section of FIG. In the BB ′ cross section shown in FIG. 11, the inclination angle of the duct body 9a (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, the water flow just above the rotation axis C1 flows into the rear edge 6a of the duct body 9a. Since the water flow in this region has a large component in the radial direction, the duct body 9a can generate a larger propulsive force when the duct body 9a has a large inclination.

  On the other hand, in the CC ′ cross section shown in FIG. 12, the inclination angle of the duct body 9a (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 ′. Therefore, the duct body 9a can generate a larger propulsive force because the inclination of the duct body 9a with respect to the direction of the rotation axis C1 is small.

  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 9a is around 0 to 20 degrees. Accordingly, the shape of the duct body 9a 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 main body 9a 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. Design θ1, θ2).

  In this embodiment, shapes other than the duct main body 9a of FIG. 9 are also considered. For example, a modified example in which the shape of the leading edge 6a is an arc and the shape of the trailing edge 7a is a curve (for example, a parabola) whose height is lower than the trailing edge side circle C3 as φ1 is smaller is conceivable. Even with such a shape, since the inclination of the duct body 9a is larger in the region where φ1 is smaller, a high propulsive force can be obtained according to the flow velocity distribution.

  FIG. 13 is a front view of a duct device 5a according to the third embodiment of the present invention. The duct device 5a in the present embodiment includes the same duct body 9a as in the second embodiment. Instead of this, the same duct body 9 as in the first embodiment may be used. The duct device 5a according to the third embodiment further includes reaction fins 12 including at least one blade (two blades in the example of FIG. 13). 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. 14 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. 13, the reaction fin 12 is supported by the duct main body 9a at the end of the base (the side close to the rotation axis C1). 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 main body 9a, and can be disposed only in a region having a radius of 0.5 or more with the highest effect. 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, 5a Duct apparatus 6, 6a Front edge 7, 7a Rear edge 8 Bossing 9, 9a Duct body 10 Support part 11 Area | region 12 Reaction fin 12a Negative pressure surface 12b Pressure surface 101 Hull 102 Stern part 103 propeller 104 rudder 105 duct device 106 area 107 suction surface 108 pressure surface C1 rotation axis C2 conical surface C3 front edge side circle C4 rear edge side circle C5 rotation surface f1, f2 water flow f101 lift force f102 drag force f103 driving force V vertical line

Claims (6)

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 trailing edge located on the rear side of the ship and having an arc with the rotation axis of the propeller inside, and a contour shape in a direction perpendicular to the rotation axis falls within a region of 0.5R or less with the radius of the propeller as R When,
A duct device having a front edge which is located on the front side of the ship, draws an arc having the rotation axis inside, and has a contour shape in a direction perpendicular to the rotation axis larger than the rear edge. 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. The duct device according to claim 1, wherein the duct body has an angle in a circumferential direction of the rotating shaft from an upward vertical line within 50 degrees. 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. The duct device according to any one of claims 1 to 3, wherein a position closer to a vertical line is larger. 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.

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