WO2018123028A1 - Bow shape - Google Patents

Abstract

This bow shape comprises a recess 1a having a pair of inclined shapes opening towards the front in the left-right direction, at least above the load waterline.

Description

Bow shape

The present invention relates to a bow shape.

Ships navigating the ocean are equipped with bow valves to reduce wave resistance in plain water and improve propulsion performance. For example, the bow valve shown in Patent Document 1 can cancel the waves created by the hull due to the protruding shape of the bow under the waterline.

Japanese Unexamined Patent Publication No. 2012-96756

In recent years, there is a tendency to set the design ship speed low for the purpose of reducing the global warming gas discharged from the ship. For ships with a low design boat speed, the shape on the waterline near the bow end is enlarged, the width of the bow is wide, and the surface shape of the bow end is a substantially flat surface perpendicular to the full length of the hull. The reflection of the incident wave incident on the bow end in the traveling direction of the ship tends to increase. As a result, the ship receives a force, that is, resistance, in the direction opposite to the traveling direction due to the reflection of the incident wave when navigating in the waves. As a result, the propulsion performance is reduced in the ship.

In view of the above-described problems, the present invention aims to improve propulsion performance by reducing reflected waves generated by the bow in the waves.

The bow shape according to the aspect of the present invention includes a depression portion having a pair of inclined surfaces opened forward in the width direction of the ship on the full-length water line.

In the bow shape according to the above embodiment, the indented portion has a deepest point where the depth is the deepest on the hull center line, and a height H _dnt from the bottom of the deepest point is a height d _{max of the} full load waterline. The width B _dnt from the ship side end of the inclined surface to the hull center line is 0.1B ≦ B with respect to the maximum width B, with a range of _0.8 d _max ≦ H _dnt ≦ 1.5 d _max. It is the range of _dnt .

In the bow shape according to the embodiment, the depth L _dnt of the deepest point in the hull length direction of the recess is formed in a range of 0.005L ≦ L _dnt with respect to the full length L.

According to the present invention, it has an inclined surface that forms a recess on the hull centerline. By the inclined surface, the wave incident from the traveling direction of the ship having the bow shape according to the present invention can be reflected in the direction inclined from the traveling direction of the ship to the ship side direction. Thereby, the ship which has the bow shape which concerns on this invention can reduce the component of the force which goes to the direction opposite to the advancing direction among the reaction forces received from a reflected wave. Therefore, the bow shape concerning the present invention can improve propulsion performance in the waves.

1 is an XZ sectional view of a bow shape according to an embodiment of the present invention. FIG. 3 is an XZ cross-sectional view taken along a bow-shaped hull center line according to an embodiment of the present invention. 1 is a XY cross-sectional view of a bow shape according to an embodiment of the present invention. It is a graph which shows the change of the total resistance coefficient by the change of the height of the hollow part in the bow shape which concerns on this invention. It is a graph which shows the change of the resistance increase coefficient by the change of the depth of the hollow part in the bow shape which concerns on this invention. It is a graph which shows the change of the resistance increase coefficient by the change of the width | variety of the hollow part in the bow shape concerning this invention. It is a graph which shows the comparison of the cross-sectional wave resistance increase coefficient in the bow shape which concerns on one Embodiment of this invention, and the conventional bow shape. It is a graph which shows the change of the resistance increase coefficient by the change of the wavelength of the wave which injects with respect to the bow shape which concerns on one Embodiment of this invention.

Hereinafter, an embodiment of a hull shape according to the present invention will be described with reference to the drawings. In the following description, the full length direction of the hull is defined as the X direction, the width direction of the hull is defined as the Y direction, and the height direction of the hull is described as the Z direction. FIG. 1 is an XZ sectional view of a bow shape 1 according to the present embodiment. FIG. 2A is an XZ sectional view taken along the hull center line of the bow shape 1 according to the present embodiment. FIG. 2B is an XY cross-sectional view of the bow shape 1 according to the present embodiment.

A ship S to which the bow shape 1 according to the present embodiment is applied is a low-speed sailing ship defined by a total length L ≧ 180 m, a hull enlargement degree C _B ≧ 0.75, and a bow waterline area coefficient C _WF ≧ 0.85. It is. The conventional bow shape O applied conventionally in such a ship S has a uniform and gentle curved surface from the bow end to the ship side, as shown by a broken line in FIGS. 1 and 2B. As shown in FIG. 1, the outer wall surface of the bow of the conventional bow shape O is substantially perpendicular to the ship bottom.

The bow shape 1 according to the present embodiment is symmetric with respect to the hull center line, and in the XY cross section of the full load waterline, the two protrusions symmetric with respect to the hull center line gradually move in the traveling direction. It has a protruding double-headed shape. That is, the bow shape 1 has the inclined surface 1b formed symmetrically with respect to the hull center line. As shown in FIG. 2B, the inclined surface 1b has a position P (deepest depth) in the XY cross section at the height H _dnt in the Z direction (see FIG. 2A) on the hull center line. The mortar-shaped hollow part 1a which has a point) is formed. As shown in FIG. 1, the bow shape 1 is substantially vertical from the deck line to the position P in the XZ cross section on the center line of the hull, and is inclined downward from the position P and protrudes in the traveling direction. Shape.

The inclined surface 1b is formed from the deck line to the position P. The inclined surface 1b has a width of B _dnt from the hull center line, and an inclination angle from the traveling direction is determined by the depth L _dnt and the width B _{dnt of} the hollow portion 1a. The inclined surface 1b reflects waves incident from the direction along the ship length direction in a direction inclined from the traveling direction of the ship S to the ship side direction.

The conditions for forming the above-described depression 1a will be described with reference to FIGS.
First, a simulation was performed on the total resistance coefficient _CT and _{WV in} waves by changing the height H _dnt from the ship bottom at position P. FIG. 3 is a graph in which the horizontal axis represents H _dnt / d _max , and the vertical axis represents the total wave resistance coefficient _{CT , WV} . d _max indicates the height in the Z direction from the bottom of the ship to the full waterline. The total resistance coefficient _{CT, WV} in the waves indicates the total resistance acting on the hull when navigating in the waves, and is a value normalized by the total resistance value of the conventional bow shape. As shown in FIG. 3, the bow shape 1 of this embodiment is different from that of the bow shape member of the conventional bow shape O in the range of H _dnt / d _max of 0.8 or more and 1.5 or less. The total resistance coefficient _{CT, WV in the} waves is lower than that of the bow member. That is, by forming the hollow portion 1a in the range of 0.8d _max ≦ H _dnt ≦ 1.5d _max , the total resistance in the waves can be reduced as compared with the conventional bow shape.

The resistance increase coefficient K _AW was simulated by changing the depth L _dnt of the recess 1a. FIG. 4 is a graph in which the horizontal axis represents L _dnt / L and the vertical axis represents the resistance increase coefficient K _AW . L shows the full length of the hull to which the bow shape of this embodiment was applied. Resistance increase coefficient K _AW, when compared with the sail in the calm water, shows a degree of increase in resistance during regular waves. As shown in FIG. 4, the bow member prior bow shape O, resistance increase coefficient _{K AW} is 1.227. On the other hand, in the bow shape 1 of the present embodiment, the resistance increase coefficient K _AW is decreased when L _dnt / L is 0.005 or more.

The resistance increase coefficient K _AW was simulated by changing the width B _dnt where the inclined surface 1b is formed from the ship side end of the inclined surface 1b to the hull center line. FIG. 5 is a graph in which the horizontal axis represents the width B _dnt / B and the vertical axis represents the resistance increase coefficient K _AW . B shows the maximum width of the hull to which the bow shape of this embodiment was applied. As shown in FIG. 5, the bow member prior bow shape O, resistance increase coefficient _{K AW} is 1.227. On the other hand, in the bow shape 1 of the present embodiment, the resistance increase coefficient K _AW is decreased when B _dnt / B is 0.10 or more.

As described above, in order to reduce the total resistance coefficient CT _{, WV} and the resistance increase coefficient K _AW in the waves, the depression 1a is set to 0.8 d _max ≦ H _dnt ≦ 1.5 d _max and B _dnt /B≧0.10. It is desirable to form in the range.

In the ship S having the bow shape 1 according to this embodiment, the inclined surface 1b reflects the incident wave incident on the bow end from the hull traveling direction in the ship side direction. The bow surface on the side of the inclined surface 1b reflects the incident wave toward the ship side as in the conventional case. For this reason, in the bow, the reflected wave which goes to the ship S advancing direction reduces, and the force which goes to the hull rear received from a reflected wave is reduced. That is, the ship S having the bow shape 1 according to the present embodiment can reduce the resistance in the waves.

FIG. 6 is a graph showing a comparison of the cross-wave resistance increase coefficient between the bow shape 1 according to the present embodiment and the conventional bow shape O. In the graph of FIG. 6, the position in the X direction of the cross section parallel to the Y direction and the Z direction with respect to the ship length is taken as the horizontal axis, and the three-dimensional bow pressure distribution is integrated in the cross section parallel to the Y direction and the Z direction. The vertical axis represents the resistance increase coefficient in the cross-sectional wave. FIG. 6 is a simulation result in water in which the ship S of the present embodiment generates a directional wave with a wavelength / captain length = 0.6. As shown in the graph of FIG. 6, the bow shape 1 of the present embodiment has a greater difference from the bow member of the conventional bow shape O with a wave resistance increase coefficient as it approaches the bow end. That is, the bow shape concerning this embodiment can reduce resistance in the bow end in waves.

FIG. 7 is a graph in which the horizontal axis represents wavelength / captain and the vertical axis represents the resistance increase factor in waves. The graph of FIG. 7 shows that the ship resistance having a bow shape 1 according to the present embodiment has a wave resistance increase coefficient reduced by about 20% at the maximum as compared with the conventional boat S having a bow shape O. Thereby, compared with the ship S of the conventional bow shape O, the total propulsion output can be reduced about 2% on average wave conditions in a real sea area.

According to the bow shape 1 according to the present embodiment, the inclined surface 1b that reflects the incident wave toward the ship side is formed at the bow end. Thereby, the ship S which has the bow shape which concerns on this embodiment compared with the case where it has the conventional bow shape O among the reaction force by the reflected wave which generate | occur | produces in a wave, the force which goes to the direction opposite to a advancing direction It is possible to reduce the components. Therefore, the bow shape 1 according to the present embodiment can improve the propulsion performance by reducing the reflected wave generated by the bow during the wave.

The present invention can be used for the bow shape of a ship.

S …… Vessel 1 …… Bow shape 1a …… Depression 1b …… Inclined surface

Claims (3)

A bow shape characterized in that a hollow portion having a pair of inclined surfaces opened in the ship width direction and forward is provided on the full-length water line. The depression is
It has the deepest point where the depth is deepest on the hull centerline,
Wherein the ship side end of the height _{H dnt} a range of _{0.8d max} ≦ _{H dnt} ≦ _{1.5d max} the height _{d max} of the load line the inclined surface from the vessel bottom of the deepest point The bow shape according to claim 1, wherein the width B _dnt to the hull center line is within a range of 0.1B ≤ B _dnt with respect to the maximum width B. _3. The bow shape according to claim 2, wherein a depth L _dnt of the deepest point in the hull length direction of the hollow portion is formed in a range of _0.005 L ≦ L _dnt with respect to the total length L. 4.

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