JP4654014B2 - Large low-speed enlargement ship - Google Patents

Description

  The present invention relates to a large-sized low-speed enlargement ship having a bow valve for reducing wave resistance. More specifically, in addition to a low valve capable of improving propulsion performance in a ballast state, the propulsion performance in a full state is improved. It is related with the structure of the bow part of the large-sized low-speed enlargement ship provided with the high valve which can be done.

  On large vessels such as tankers and bulk carriers, a bow valve (Bulbous Bow) is provided at the bow to reduce wave resistance in plain water. This bow valve is installed at the bottom of the bow to counteract the waves created by the hull in order to reduce the frictional resistance, pressure resistance, wave resistance, and air resistance among the components of propulsion resistance in plain water. Structure.

  And this bow valve shifts the position of the wave generated at the bow and makes it interfere well with the wave generated behind it, thereby reducing the overall wave resistance. In addition, the low-speed enlargement ship also has the effect of reducing the vortex resistance by adjusting the flow of water near the bow.

  Conventionally, there are a normal large-sized valve 3 as shown in FIG. 4 and a low valve 10 as shown in FIG.

  This normal large-sized valve 3 is a valve that is generally used. However, in the case of a full load as shown in FIG. ) And a hull without a valve (curve C), in the high speed range where the Froude number Fn is 0.155 or more, the wave produced by the normal large-sized valve 3 and the wave produced by the main hull 2 interfere with each other due to the general valve effect. The wave resistance is reduced, and the wave resistance is smaller with the valve.

  On the other hand, in the low speed region where the Froude number Fn is 0.135 or less, the wave produced by the normal large-sized valve 3 and the wave produced by the main hull 2 are overlapped without interfering with each other. growing. Further, in the intermediate speed range, that is, 0.135 ≦ Fn ≦ 0.155, there is no significant difference in the wave resistance rw between the normal large-sized valve-equipped hull (curve B) and the non-valve hull-shaped (curve C). .

The Froude number Fn is a dimensionless display with respect to the ship speed Vs (m / s). When the length between the normals of the ship is Lpp (m) and the gravitational acceleration is g (m / s ² ), Fn = Vs / (G × Lpp) ^1/2

  This normal type hull with large valve has a larger valve area and submerged area than a hull without valve, so the frictional resistance increases by that area, so the wave-making resistance will change in the intermediate speed range. Even if it is not, the frictional resistance becomes large, so the hull with a normal large-sized valve is disadvantageous in terms of propulsion performance when fully loaded.

  And in the case of a ballast (light load) state, since it becomes shallow draft, breaking wave resistance becomes remarkable and a big wave-making resistance generate | occur | produces. The normal type large-sized valve has a large length near the ballast water line db and a small incident angle at the bow end on the surface of the water line. Therefore, it is effective in the ballast state.

  On the other hand, by improving the drawbacks of the above-mentioned normal-type large-valve hull 1X, a low-valve hull 1Y as shown in FIG. 5 was born. The vicinity of the full draft df is close to a hull without a valve. Therefore, in the intermediate speed range in the full load state, that is, 0.135 ≦ Fn ≦ 0.155, there is no significant difference between the normal type large valve-equipped hull form (curve B) and the wave resistance rw. Rather, it is more advantageous than a normal large hull with a valve because of the small flooded area.

  Further, it is known that the protruding valve is effective for remarkable wave breaking resistance. Therefore, a low valve is provided with a projecting valve specialized for improving the wave-making resistance in the ballast state from the vicinity of the ballast draft db, and this low valve is attached as shown in FIG. 7 showing the wave-making resistance in the ballast state. The ship-shaped valve (curve A) has a reduced wave resistance rw as compared with the hull form with a large-sized valve (curve B) as well as the hull form (curve C). In the figure, Fnd is the fluid number corresponding to the design speed.

  On the other hand, in the ship's bow shape, it has a spherical bow for the full load state below the light load water line in the lower part near the full load water line, and a spherical bow part for the light load state in the vicinity of the light load water line. The front part of the spherical bow part for the full load state is formed in a substantially bowl shape by connecting smoothly between the bow parts with a constricted part made of a concave curved surface in the front shape. In order to accelerate the upper water, it is formed in a flat shape in the width direction of the ship, the full load water line is positioned near the upper surface of the upper surface, and the light load water line is positioned substantially coincident with the starting point of the constricted portion. A bowed bow shape has been proposed (see, for example, Patent Document 1).

  However, in this bow shape, there is a problem that the flooded area increases and the frictional resistance increases because the spherical bow for full load and the spherical bow for light load are smoothly connected at the constricted portion. . Moreover, since the upper surface of the spherical bow portion for full load is formed in a flat shape, there is a problem that it is disadvantageous in terms of the structure with respect to wave driving and the like.

  In addition, a bow valve is provided between the bottom base line and the ballast water line, and an auxiliary valve is provided between the ballast water line and the full load water line, so that it can be used for both full load and ballast water conditions. A bowed structure with a valve formed so as to reduce the wave-making resistance is proposed (see, for example, Patent Document 2).

However, the bow valve has a structure for reducing the wave resistance in the ballast draft state, and it is smaller than the bow valve in the full load state, so even if the wave resistance reduction effect by the auxiliary valve is added, in the full load state, There is a problem that the wave resistance reduction effect may be insufficient. In ballast draft conditions, the surface of the water comes between the bow valve and the auxiliary valve, so the vertical force due to the waves acts on the auxiliary valve, and even in the full draft state, the auxiliary valve is placed just below the water surface. Therefore, even in this state, there is a problem that the vertical force due to the waves acts on the auxiliary valve, which may increase the bowing (pitching). In addition, there is a problem that it is necessary to change the design method of the bow valve structure in the full load state from the conventional single bow valve to the spherical bow portion for the full load state.
Japanese Patent No. 3375743 JP-A-9-66885

  The present invention has been made to solve the above-mentioned problems, and its purpose is to improve the propulsion performance at full load while taking advantage of the low valve in a large-scale low-speed enlarged ship having a low valve at the bow. An object of the present invention is to provide a large-sized low-speed enlargement ship that can improve propulsion performance not only in a ballast state but also in a full load state.

In order to achieve the above object, the large low-speed enlargement ship of the present invention has a vertical length of 250 m or more, a square coefficient of 0.8 or more, and a voyage speed of 0.135 or more when converted to a fluid number. The base valve is a high valve for improving wave resistance during full load navigation on a large, low-speed enlarged ship with a low valve for improving wave resistance during ballast navigation below the ballast draft at the bow. The height of the lower end position of the high valve is dHB1, and the height of the full load water line is df, so that 0.6 df ≦ dHB1 ≦ 0.9 df, and the upper valve position height of the high valve is provided near the full load draft. further, the gaps Haibarubu and Robarubu by spaced in the forward perpendicular provided independently between the upper end of the forward perpendicular of the lower end and Robarubu in the forward perpendicular of Haibarubu Kicking with, between said Haibarubu and bow flare, its cross-section the skeg for Waves resistance increase reduction in a plan view is constructed by providing forms to be wedge-shaped.
Further, in the large-sized low-speed enlargement ship, the tip position on the upper end side of the skeg is the same as or behind the tip position of the bow flare part, and the tip position on the lower end side of the skeg is the same as the tip position of the high valve. To do.

This Froude number Fn is a dimensionless display with respect to the ship speed Vs (m / s). When the length between the normals of the ship is Lpp (m) and the gravitational acceleration is g (m / s ² ), Fn = Vs / (G × Lpp) ^1/2 . Note that the nautical speed is sometimes referred to as the planned speed or the like, and therefore the nautical speed is assumed to include the planned speed in this case as well.

  And this large-sized low speed enlargement ship has a low valve in the ballast state, and therefore has the same propulsion performance as a conventional hull form with a low valve. In the full load state, the high valve drainage amount is small, so the wave produced by the high valve itself is smaller than that of the normal large valve with a large drainage amount, and the wave resistance is smaller than that of the normal large valve. Furthermore, since the shape of the high valve protrudes, the high valve exhibits an effect of reducing the bow breaking resistance, and the wave-making resistance is further smaller than that of the normal large-sized valve.

  In addition, since the high valve is not near the water surface in the ballast state, the wave does not hit the lower side of the high valve or reflect the incident wave.

  In addition, since the skeg has a wedge-shaped cross section in a plan view, that is, a wedge-shaped cross section in a horizontal plane, it is divided into both sides without reflecting the wave incident on the bow portion in a full state. Therefore, it has a function of suppressing an increase in resistance due to a reflected wave in a wave in a full state. In addition, because it is located above the full draft, there is little amount of waves and there is almost no increase in resistance in plain water. Moreover, since the bow flare part and the bow end side of the high valve are structurally connected, it also has a function of increasing the strength in the vertical direction.

  And in the above-mentioned large-scale low-speed enlargement ship, the ship's mold width is set to B, and the bow perpendicular F.V. P. When the width of the high valve at the position is BHB, 0.1B ≦ BHB ≦ 0.3B. Alternatively, the ship's mold width is B and the bow perpendicular F.R. P. In this position, when the width of the skeg is BS and the width of the high valve is BHB, 0.1B ≦ BS ≦ BHB ≦ 0.3B. With these configurations, the size of the skeg and the wedge-shaped shape of the bow, particularly the angle at the bow can be made appropriate.

  According to the large-sized low-speed enlargement ship of the present invention, in a ballast state, the wave-making resistance can be reduced by a low valve, in a full load state, the wave-making resistance can be reduced by a high valve with a small amount of drainage, and the bow breaking resistance is reduced by skeg. Thus, the increase in resistance in the waves can be reduced.

  Accordingly, it is possible to provide a large, low-speed enlargement ship having excellent propulsion performance near the voyage speed (planned speed) in both the full load state and the ballast state.

  Embodiments of a large-scale low-speed enlargement ship according to the present invention will be described below with reference to the drawings.

  In the present invention, a large ship having a vertical length Lpp of 250 m or more, an enlarged ship having a square coefficient Cb of 0.8 or more, and a voyage speed (planned speed) Vs of 0. The target is low-speed large low-speed enlargement ships that are 135 or more and 0.155 or less.

  And as shown in FIGS. 1-3, the large-sized low speed enlargement ship 1 which is embodiment which concerns on this invention is the wave resistance at the time of ballast navigation from the ballast draft (light load draft) db vicinity of a bow part downward. A low valve 10 for improvement is provided. The low valve 10 has a protruding valve shape, and can reduce the wave-making resistance in the ballast state (light load state) and can also reduce the wave breaking resistance.

  In the present invention, in the large-sized low-speed enlarged ship 1 with the low valve 10, the high valve 30 for improving the wave-making resistance at the time of full sailing is replaced with the baseline B.I. L. When the height of the lower end position of the high valve 30 is dHB1 and the height of the full load water line is df, 0.6df ≦ dHBl ≦ 0.9 df, and the height dHBh of the upper end position of the high valve 30 is set to the full load draft df. Provided in the vicinity, for example, 0.90 df ≦ dHBh ≦ 1.10 df.

  The high valve 30 is a structure in which a bow portion below the full draft df is inflated in a bulb shape, and is formed into a shape that reduces wave-making resistance and wave breaking resistance in a full state in accordance with a normal bow valve design method. However, the width of the high valve 30 is equal to the bow perpendicular F.R. P. When the width at the position of B is BHB, it is within the range of 0.1 to 0.3 times the ship width (form width) B. That is, 0.1B ≦ BHB ≦ 0.3 B.

  The shape of the high valve 30 viewed from the front is roughly a shape close to an elliptical shape having a short axis or a long axis in the vertical direction. Further, as shown in FIG. 2, in the side view, the front end position of the high valve 30 is the position of the foremost portion of the bow flare portion 20 or the rearward position thereof. Further, the positional relationship with the tip position of the low valve 10 is the tip position or a position behind the tip position. Further, the rear portion of the high valve 30 is formed so as to be smoothly continuous with the hull 2. And the shape of the front side of the high valve 30 is formed as a shape substantially close to a half of an elliptical shape having a major axis in a substantially horizontal direction.

  The high valve 30 is formed in a shape that reduces the wave resistance in a full load state, and the high valve 30 itself has a small amount of drainage. Therefore, the wave produced by the high valve 30 itself is smaller than that of a normal large valve having a large amount of drainage. The wave resistance is smaller than that of the normal large valve. Further, since the high valve 30 has a protruding shape, it exhibits an effect of reducing the bow breaking resistance, and the wave resistance is smaller than that of the normal large valve. Moreover, since the high valve 30 is not near the water surface in the ballast state, the wave does not hit the lower side of the high valve 30 or reflect the incident wave.

  In the present invention, a skegg 40 for reducing the increase in resistance in waves is formed between the high valve 30 and the bow flare portion 20 so as to have a wedge-shaped cross section in plan view. As shown in FIG. 3, the tip position on the upper end side of the skeg 40 is the same as or behind the tip position of the bow flare portion 20, and the tip position on the lower end side of the skeg 40 is the tip position of the high valve 30. The position is the same as or behind the position, and the maximum width BS of the skeg 40 is preferably equal to or less than the width BHB of the high valve 30. In particular, the bow perpendicular F.R. P. In this position, when the width of the skeg 40 is BS and the width of the high valve 30 is BHB, it is preferable that 0.1B ≦ BS ≦ BHB ≦ 0.3 B. And when it looks down from upper direction, it forms so that the projection surface of the skeg 40 may enter in the projection surface of the high bulb 30.

  The angle α of the bow portion of the skeg 40 is an angle formed between the starboard side and the port side, and is preferably in the range of 20 degrees to 50 degrees. Further, the skeg 40 may be additionally provided at the bow portion. In this case, the skeg 40 can be structurally simplified and the weight increase can be reduced. Further, the skeg 40 does not necessarily need to fill the entire space between the bow flare portion 20 and the high valve 30 in a side view, and the bow side may be retreated with respect to the longitudinal direction of the ship. You may arrange | position only near the full load water line between the flare part 20 and the high valve | bulb 30. FIG.

  Since the skeg 40 has a wedge-shaped cross section in a plan view, that is, a wedge-shaped cross section in a horizontal plane, the skegg 40 is cut into both sides without reflecting the wave incident on the bow portion in a full state. Therefore, it is possible to suppress an increase in resistance due to reflected waves in the waves in a full state.

  In addition, because it is located above the full draft, there is little amount of waves and there is almost no increase in resistance in plain water. Further, since the bow flare portion 20 and the bow end side of the high valve 30 are structurally connected, the strength in the vertical direction can be increased.

  According to the large-sized low-speed enlargement ship 1 configured as described above, the wave-making resistance can be reduced by the low valve 10 in the ballast state, and the wave-making resistance can be reduced by the high valve 30 having a small amount of drainage in the full load state. It is possible to reduce the wave breaking resistance increase by reducing the bow breaking resistance. Therefore, in the vicinity of the voyage speed (planned speed) Vs, excellent propulsion performance can be exhibited both in the full load state and in the ballast state.

It is a perspective view of the bow part of the large-sized low-speed enlargement ship of embodiment which concerns on this invention. It is a side view of the bow part of the large-sized low speed enlargement ship of FIG. It is a figure which shows the AA cross section and BB cross section of the bow part of the large sized low speed enlargement ship of FIG. It is a side view which shows the shape of the bow part of the hull form with the normal type large sized valve of a prior art. It is a side view which shows the shape of the bow part of the boat type | mold with a low valve of a prior art. It is a figure which shows the wave-making resistance in the full load state of the hull form with a normal type large valve and the hull form without a valve. It is a figure which shows the wave-making resistance in the ballast state of the hull with a low valve, the hull with a normal large-sized valve, and the hull without a valve.

Explanation of symbols

1 Large low-speed enlargement ship 10 Low valve 20 Bow flare 30 High valve 40 Skeg B Ship width (form width)
BHB High valve width L. Baseline df Full load water line, Full load water line height db Ballast water line dHBl High valve lower end position height dHBh High valve upper end position height Fn Fluid number F. P. Bow perpendicular

Claims (2)

When the length between perpendiculars is 250m or more, the square coefficient is 0.8 or more, and the cruising speed is converted to Froude number, it is 0.135 or more and 0.155 or less, and the ballast sails from near the ballast draft at the bow. In a large low-speed enlarged ship equipped with a low valve for improving wave resistance at the time of operation, the high valve for improving wave resistance during full sailing is set to dHB1 at the lower end of the high valve from the base line, and the height of the full load water line When the height is df, 0.6 df ≦ dHB1 ≦ 0.9 df, the high valve top end height is set near the full draft, and the high valve and the low valve are separated from each other at the bow perpendicular line and provided independently. converting mechanism provide a gap between the upper end of the forward perpendicular of the lower end and Robarubu in the forward perpendicular of Haibarubu, between the Haibarubu and bow flare, waves Large low-speed Ship that cross the skeg for increased resistance reduced in a plan view, characterized in that provided formed to be wedge-shaped.   The tip position of the upper end side of the skeg is the same as or behind the tip position of the bow flare, and the tip position of the lower end side of the skeg is the tip position of the high valve. Large low-speed enlargement ship.

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