JP2017077754A - Stern structure of ship and ship - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stern shape of a ship which reduces a wave resistance at a stern of the ship in which a recess is formed on a stern bottom of a propeller upper part.SOLUTION: A ship bottom surface 2e constituting a stern tunnel 3 is formed in such a manner that the ship bottom surface is changed from an ascent inclination toward an upper part 2c of a propeller 4 from a forward ship bottom into a descent inclination toward a stern end 2a, an inflection part 3b which shifts from the ascent inclination to the decent inclination, is provided at a rear position with respect to the propeller 4, the ship bottom surface constituting the stern tunnel 3 in a part toward the stern end 2a from the inflection part 3b is maintained to the stern end, and a curvature degree of the recess in a cross sectional shape thereof is continuously reduced.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a stern shape of a ship, and more particularly to a stern structure of a ship and a ship that can reduce stern wave resistance in a ship having a stern bottom formed in a tunnel shape.

  Conventionally, a tunnel hull form that forms a tunnel shape at the bottom of a ship at the stern of a ship has advantages in various aspects, such as ensuring the lateral stability of the ship and reducing wave resistance, and ensuring the clearance between the propeller and the hull. Has been adopted.

  For example, as the stern shape of a ship that can secure the distance between the propeller and the stern bottom and reduce the wave-making resistance, the tunnel shape has a transverse cross-sectional shape that curves upward and extends in the front-rear direction. A stern shape to be formed has been proposed (see, for example, Patent Document 1).

  As illustrated in FIG. 4, the stern structure of the ship 1X formed in the tunnel shape according to the prior art is such that, in a side cross-sectional shape, the bottom surface 2e of the stern portion 2 is inclined upward from the top of the propeller 4 to the stern end 2a. It is formed to maintain. Therefore, in this stern structure 1X, the water flow rising along the bottom surface 2e during navigation is discharged upward at the stern end 2a while maintaining momentum. It becomes. As described above, the stern structure of the prior art still has a problem to be improved in reducing the wave resistance.

  Further, in such a stern structure 1X of the ship, since the bottom 2e close to the stern end 2a faces upward, as shown in FIG. 6, the hull is tilted by pitching (pitch) during actual sea area navigation. When the bow descends and the stern rises, air a easily enters the stern bottom 2e from the stern end 2a side, and the air a is engulfed in the recess of the stern tunnel 3X, and the wavefront hits the stern bottom 2e of the stern tunnel 3X, that is, punching There was also a problem that noise was generated by doing so.

JP-A-6-344773

  An object of the present invention is to provide a stern structure of a ship and a ship capable of reducing stern wave resistance in a ship having a stern bottom formed in a tunnel shape.

  In order to achieve the above object, the stern shape of the ship according to the present invention is a stern structure of a ship having a stern tunnel that guides the water flow along the bottom of the ship to the top of the stern propeller during navigation. The bottom surface of the ship is formed by changing from an ascending slope toward the upper part of the propeller from the front ship bottom to a descending slope toward the stern end, and an inflection part that transitions from the ascending slope to the descending slope is located behind the propeller. In addition to maintaining the bottom of the stern tunnel that forms the stern tunnel in the region from the inflection part toward the stern end to the stern end, the degree of curvature of the recess in the cross-sectional shape is continuously reduced. It is formed to be configured.

  According to this configuration, the upward flow from the front ship bottom toward the top of the propeller changes to the downward flow from the inflection part to the stern end at the inflection part. Wave collapse and wave generation at the edge are suppressed, and stern wave resistance is reduced. Furthermore, since the tunnel-shaped ship bottom is maintained up to the stern end, the effect of reducing the wave-making resistance due to the formation of the stern tunnel can be exhibited.

  Moreover, the bottom end position of the stern end can be positioned below compared to the case where the inflection portion is not provided while the bottom surface of the stern stern at the top of the propeller is formed in a side sectional shape curved upward. Therefore, even when the bow descends due to pitching and the stern rises during navigation, air enters the stern from the stern to the stern tunnel, making it difficult to entrain the air in the recess of the stern tunnel. Therefore, it is possible to suppress the generation of noise caused by the wavefront hitting the ship bottom.

  In the stern structure of the ship, a horizontal distance from the top of the propeller to the stern end is a distance Xa, and a horizontal distance from the top of the propeller to the position of the inflection part is a distance X1 with respect to the distance Xa. When the inflection part is arranged at a position where the ratio of the distance X1 is in the range of 0.3 to 0.8, tunnels such as securing lateral recovery force and reducing wave resistance in the stern tunnel While maintaining the effect, it is possible to exert a noise suppression effect by reducing the wave-making resistance at the stern and reducing the air entrainment during pitching, and both effects can be exhibited in a balanced manner.

  Furthermore, in the stern structure of the ship described above, the vertical distance H1 between the lowest end position and the highest end position of the stern tunnel in the cross section of the stern end is 0.05 times or more and 0.2 times the propeller diameter Dp. If the vertical distance H2 between the lowermost position and the uppermost position of the stern tunnel in the cross section of the inflection part is set to 0.3 times or less of the propeller diameter Dp, In addition, while maintaining the tunnel effect such as securing the transverse restoring force and reducing the wave-making resistance, it can exert the noise suppression effect by reducing the wave-making resistance at the stern and the air entrainment when pitching swaying, balancing both effects Can be used well.

  In order to achieve the above object, when the ship of the present invention is configured to have the stern shape of the above ship, this structure can exhibit the same effect as the stern shape of the above ship.

  According to the stern shape of the ship and the ship of the present invention, the upward flow from the front ship bottom to the upper propeller changes to the downward flow from the inflection part to the stern end at the inflection part. As a result, wave collapse and wave generation at the stern end are suppressed, and stern wave resistance is reduced. Furthermore, since the tunnel-shaped ship bottom is maintained up to the stern end, the effect of reducing the wave-making resistance due to the formation of the tunnel shape can be exhibited.

It is a sectional side view of the stern part of the ship which has the stern shape of the ship of embodiment which concerns on this invention. It is A arrow directional view of FIG. It is a sectional side view of the stern part which shows the situation where the bow of the ship of FIG. 1 descended by pitching and the stern rose. It is a sectional side view of the stern part of the ship which has a stern tunnel of a prior art. It is a B arrow view of FIG. It is a sectional side view of the stern part which shows the situation where the bow of the ship of FIG. 4 descended by pitching and the stern rose.

  Hereinafter, a stern shape of a ship and a ship according to embodiments of the present invention will be described with reference to the drawings. In this embodiment, the stern structure when applied to a uniaxial ship is shown and described. However, the present invention is not limited to a uniaxial ship, and for example, in a biaxial ship or a triaxial ship, each propeller is used. On the other hand, by forming a stern tunnel for each, it can be applied in the same manner as in the case of a uniaxial ship.

  As shown in FIG. 1, a ship 1 according to an embodiment of the present invention includes a stern structure of a ship according to an embodiment of the present invention described below, and is similar to the stern structure of this ship. Has the effect of.

  As shown in FIG. 1 and FIG. 2, the ship 1 passes a water flow W flowing along the ship bottom surface 2 e from the ship bottom surface 2 e in front of the propeller 4 during navigation through the upper part 2 c of the propeller 4 in the stern part 2, A stern structure of a ship having a stern tunnel 3 leading to the stern end 2a is provided. The stern tunnel 3 has a propeller tip clearance (gap) between the propeller 4 and the bottom surface 2e on the bottom surface 2e of the stern part 2. , And reaches the stern end 2a from the upper part of the rudder 5.

  As shown in FIG. 1, the stern tunnel 3 has a side cross-sectional shape at the center of the hull in which the bottom surface 2e of the propeller upper portion 2c is curved upward, in other words, has a side cross-sectional shape that is convex upward. On the other hand, as shown in FIG. 2, the cross-sectional shape is a shape having a concave shape that curves upward, and is configured to continue in the front-rear direction while gradually changing the curved shape.

  By providing the stern tunnel 3, the ship 1 has a submerged part (buoyancy generation) separated from both sides in the stern part, thereby ensuring the ship's lateral restoring force and reducing the wave-making resistance. Advantages such as improvement in propulsion performance and improvement in propulsion efficiency due to an increase in propeller diameter while ensuring a propeller tip clearance at the upper portion 2c of the propeller 4 are provided.

  In the present invention, the bottom surface 2e constituting the stern tunnel 3 is formed by changing the upward slope from the forward bottom surface 2e toward the upper portion 2c of the propeller 4 to the downward slope toward the stern end 2a. The inflection part 3b which shifts from the inclination to the downward inclination is provided at a position behind the propeller 4 and configured.

  In other words, the inflection part 3b that changes the ascending inclined surface 3a from the front ship bottom 2e toward the upper part 2c of the propeller 4 to the descending inclined surface 3c toward the stern end 2a at a position Pmax that is a certain distance behind the propeller 4 is provided. Provide and configure. Further, the inflection portion 3 b is the highest position in the stern tunnel 3 with respect to the ship bottom line of the ship 1.

  That is, as shown in FIG. 1, the stern tunnel 3 is formed in a concave shape having an inflection portion 3b as a vertex in a side view. In the embodiment of FIG. 1, ascending from the position Pmax of the inflection part 3b, at least between the position Pp of the propeller 4 and the position Pmax of the inflection part 3b (distance X1) in a side view. The inclined surface 3a and the descending inclined surface 3c provided between the position Pmax of the inflection part 3b and the position Pe of the stern end 2a (distance X2) are configured to have curved shapes, respectively. The ascending inclined surface 3a and the descending inclined surface 3c are continuously connected in a curved manner via the inflection portion 3b. Note that one or both of the ascending inclined surface 3a and the descending inclined surface 3c may be formed in a linear shape instead of a curved shape. In addition, the inflection portion 3b is preferably a smooth curved line in a side view and not a broken line because the water flow W can flow smoothly, but may be a broken line shape if it is not a large angle broken line shape.

  Further, in the present invention, the bottom of the stern tunnel 3 in the region from the inflection portion 3b toward the stern end 2a is maintained up to the stern end, and the curvature of the concave portion in the cross-sectional shape is continuously increased. It is formed to decrease.

  That is, in the cross-sectional shape of the stern tunnel 3, as shown in FIG. 2, the magnitude of the upward curve of the stern tunnel 3 is maintained while maintaining the upwardly curved state on the hull center line LC. In other words, the curvature radius of the curved surface showing the degree of curvature is formed so as to continuously increase from the inflection portion 3b toward the stern end 2a.

  More specifically, as shown in FIG. 2, the stern tunnel 3 is formed in a W-shaped cross-sectional shape with a central portion curved upward. An example of the magnitude of the upward curvature in the cross section of the stern tunnel 3 is, for example, from the curved top 3e that is the top of the upward curvature in the center portion of the ship bottom to the lowest curvature of the bottom of the ship bottom. It is the magnitude of the vertical distance H1 to the lower end 3f. That is, the vertical distance H1 continuously decreases from the inflection portion 3b toward the stern end 2a. Here, the lowermost curved portion 3f has a smooth curved shape without knuckle-like discontinuities so as to be able to cope with a flow component in the width direction of the hull.

  According to this structure, a change is made to change the rising slope 3a from the front ship bottom 2e toward the upper portion 2c of the propeller 4 to the descending slope 3c toward the stern end 2a at a position Pmax that is a certain distance behind the propeller 4. Since the curved portion 3b is provided, as shown in FIG. 1, the upward flow W from the front ship bottom surface 2e toward the upper portion 2c of the propeller 4 crosses the curved portion 3b as a boundary. To a downward flow W toward the stern end 2a. Therefore, as shown in FIG. 4 of the prior art, compared to the stern structure of a ship that is formed with an upward inclined surface up to the stern end 2a without the inflection part 3b, the wave breakage and structure generated at the stern end are formed. Waves are suppressed and stern wave resistance is reduced.

  Further, since the stern tunnel 3 is maintained up to the stern end 2a, in the present invention, as compared with the stern shape in which the stern end 2a is formed in a linear shape and the stern tunnel 3X is not maintained up to the stern end 2a, The effect of improving the propulsion performance by reducing the wave resistance can be maintained high.

  Further, in a side view, the stern bottom 2e of the upper part 2c of the propeller 4 is formed in a side cross-sectional shape that is curved upward, and the position of the lower end 2b of the stern end 2a is compared with the case where the inflection part 3b is not provided. Can be located below. Therefore, as shown in FIG. 3, even when the hull is inclined by θ ° with respect to the horizontal due to pitching during navigation, the bow descends and the stern rises, as compared with the stern structure shown in FIG. 6 of the prior art. Air is difficult to enter from the stern end 2a to the front bottom 2e. Therefore, in the stern structure shown in FIG. 6 of the prior art, air enters the bottom of the stern tunnel 3X and noise is generated when the wavefront hits the bottom of the stern tunnel, but this can be suppressed in the stern structure of the ship of the present invention.

  The position of the inflection part 3b in the front-rear direction is defined as a distance Xa from the top 2c of the propeller 4 to the stern end 2a and a distance X1 from the top 2c of the propeller to the inflection part 3b. It is preferable that the ratio ε (= X1 / Xa) of the distance X1 to the distance Xa is a position in the range of 0.3 to 0.8.

  If the position of the inflection part 3b is ahead of this range, the effects of general stern tunnels such as securing lateral recovery force and reducing wave resistance in the stern tunnel 3 will decrease, and the position of the inflection part 3b will be reduced. If it is behind this range, the noise suppression effect due to the reduction of wave-making resistance at the stern and the reduction of air entrainment during pitching oscillation will be reduced.

  In other words, while maintaining the tunnel effect such as securing lateral restoring force and reducing the wave-making resistance in the stern tunnel, it is possible to demonstrate the noise suppression effect by reducing the wave-making resistance at the stern and reducing air entrainment during pitching sway, Both effects can be demonstrated in a balanced manner.

  The upward curve at the stern end 2a of the stern tunnel 3 is such that the vertical distance H1 between the lowest end position of the stern end 2a and the highest end position of the stern tunnel 3 is 0.05 times the propeller diameter Dp or more. In addition, it is preferably formed so as to be 0.2 times or less (or 5% or more and 20% or less).

  In addition, the magnitude of the upward curve of the stern tunnel 3 in the transverse section of the inflection portion 3b is the lowest end position of the stern tunnel 3 and the uppermost end position of the stern tunnel 3 in the transverse section of the inflection portion 3b. It is preferable that the vertical distance H2 is formed so as to be 0.3 times or less (or 30% or less) of the propeller diameter Dp.

  Then, the amount of change ΔHi of the vertical distance Hi that is reduced continuously or stepwise from the inflection part 3b toward the stern end 2a partially including a certain portion is a distance Xi from the inflection part 3b to the stern end 2a. It may be formed so as to change at the same ratio as the change amount ΔXi of (ΔHi / ΔXi = constant), or may be formed so that the ratio of the respective change amounts is different.

  With these configurations, while maintaining the tunnel effect such as securing lateral restoring force and reducing the wave-making resistance in the stern tunnel, the noise-suppressing effect is achieved by reducing the wave-making resistance at the stern and reducing air entrainment during pitching. Can demonstrate both effects in a balanced manner.

  Therefore, according to the stern shape of the ship and the ship 1 configured as described above, the upward flow W from the front ship bottom toward the upper part 2c of the propeller 4 starts from the inflection part 3b with the inflection part 3b as a boundary. Since the flow changes to the downward flow W toward the end 2a, this suppresses wave collapse and wave formation at the stern end, and reduces stern wave resistance. Furthermore, since the tunnel-shaped ship bottom is maintained up to the stern end 2a, the effect of reducing the wave resistance due to the formation of the tunnel shape can be exhibited.

  According to the stern shape of the ship and the ship of the present invention, the upward flow from the front ship bottom to the upper propeller is made to flow downward on the stern side with the inflection part as a boundary. The stern wave resistance can be reduced by suppressing the wave collapse and wave generation that occurs in the tunnel, and the tunnel-shaped ship bottom is maintained up to the stern end, so the effect of reducing the wave-making resistance by forming the tunnel shape can be reduced. Since it can be exhibited, it can be utilized for the stern structure of many ships and ships.

1, 1X Ship 2 Stern part 2a Stern end 2b Stern end lower end 2c Propeller upper part 2d Ship bottom (baseline)
2e Stern bottom 3, 3X Stern tunnel 3a Ascending inclined surface 3b Inflection part 3c Inclining inclined surface 3e Curved apex (cross section at stern end)
3f Curved bottom end (cross section at stern end)
4 Propeller 5 Rudder a Air

Claims (4)

In the stern structure of a ship equipped with a stern tunnel that guides the water flow along the bottom of the ship to the top of the stern propeller during navigation,
An inflection portion that forms the bottom of the stern tunnel by changing from an ascending slope toward the upper part of the propeller from a forward ship bottom to a descending slope toward the stern end, and transitions from the ascending slope to the descending slope. Is provided at a position behind the propeller,
The bottom of the stern tunnel in the region from the inflection part toward the stern end is maintained up to the stern end, and the curvature of the recess in the cross-sectional shape is continuously reduced. The stern structure of a ship characterized by   The horizontal distance from the upper part of the propeller to the stern end is a distance Xa, the horizontal distance from the upper part of the propeller to the position of the inflection part is a distance X1, and the ratio of the distance X1 to the distance Xa is 0.3-0. 2. The stern structure of a ship according to claim 1, wherein the inflection part is arranged at a position in a range of .8.   A vertical distance H1 between the lowest end position and the highest end position of the stern tunnel in the cross section of the stern end is set to be 0.05 times to 0.2 times the propeller diameter Dp, and the cross section of the inflection portion The stern structure of a ship according to claim 1 or 2, wherein a vertical distance H2 between the lowermost position and the uppermost position of the stern tunnel is set to 0.3 times or less of the propeller diameter Dp.   The ship provided with the stern structure of the ship of any one of Claims 1-3.

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