Wave-making reduction device and ship equipped with the same

Abstract

The present invention provides a wave-making reduction device that suppresses wave-making to reduce wave-making resistance and can also reduce the resistance acting on the hull during low-speed navigation when the bow side sinks, and a ship equipped with the wave-making reduction device. The wave-making reduction device includes a plurality of fins (21, 22) that project from the ship side outer plate (11) along the width direction of the ship (10) on the bow (10A) side of the ship (10) and extend from the bow (10A) toward the stern. The plurality of fins (21, 22) are disposed at a position above the full load waterline (L1) in the depth direction of the ship (10). The fin (21) is disposed above the fin (22) in the depth direction of the ship (10), and the protrusion amount (P2) of the fin (22) is set to be smaller than the protrusion amount (P1) of the fin (21).

Description

Technical Field

[0001] The present invention relates to a wave-making reduction device and a ship equipped with the wave-making reduction device. Background Art

[0002] When a ship is sailing, wave-making resistance is generated near the bow due to backflow (Japanese: 引き波). To reduce this wave-making resistance, plate-shaped members (fins) such as those shown in Patent Documents 1 to 4 are sometimes installed near the bow above the waterline.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2014-189098

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2001-247075

[0007] Patent Document 3: Japanese Patent Application Laid-Open No. 2004-136780

[0008] Patent Document 4: Japanese Patent Application Laid-Open No. 4-238788 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] Sailing attitude varies according to the speed of the ship, so specifically Figure 23 As shown, the bow side sinks during low-speed sailing and floats during high-speed sailing. Therefore, by providing a plurality of fins in the depth direction of the ship, it is expected that the wave-making resistance can be reduced in accordance with various ship speeds.

[0011] However, at low speeds, the lower fin, which can be expected to experience wave return (Japanese: 波返し), may be partially submerged in water (for example, the end portion at the bow). If a portion of the lower fin is submerged in water, the submerged portion experiences resistance from the water, acting as resistance to the hull.

[0012] The present invention has been made in view of such circumstances, and aims to provide a wave-making reduction device that suppresses wave making and reduces wave-making resistance, and can also reduce the resistance acting on the hull during low-speed navigation with the bow side sinking, and a ship equipped with the wave-making reduction device.

[0013] Solutions to Problems

[0014] In order to solve the above-mentioned problems, the wave-making reduction device and the ship equipped with the wave-making reduction device of the present invention adopt the following means.

[0015] That is, the wave-making reduction device according to one aspect of the present invention includes a plurality of protruding members that protrude from the ship side outer plate along the width direction of the ship on the bow side of the ship and extend from the bow toward the stern. The plurality of protruding members are arranged at a position above the full load waterline in the depth direction of the ship. One protruding member is arranged above the other protruding members in the depth direction, and the protruding amount of the other protruding members is set to be smaller than the protruding amount of the one protruding member.

[0016] In addition, a ship according to one aspect of the present invention includes the above-described wave-making reduction device.

[0017] Advantages of the Invention

[0018] According to the wave-making reduction device of the present invention and the ship including the wave-making reduction device, the generation of waves is suppressed to reduce the wave-making resistance, and the resistance acting on the hull can also be reduced during low-speed navigation when the bow side sinks. Description of the Drawings

[0019] Figure 1 is a side view of a ship according to the first embodiment of the present invention.

[0020] Figure 2 is a perspective view of the vicinity of the bow of the ship.

[0021] Figure 3 is a front view of the ship.

[0022] Figure 4 is a bottom view of the vicinity of the bow of the ship.

[0023] Figure 5 is a side view of the vicinity of the bow of the ship.

[0024] Figure 6 is a diagram showing the recirculation at a ship without fins.

[0025] Figure 7 is a diagram showing the recirculation at the ship of the present invention.

[0026] Figure 8 is Figure 1 a cross-sectional view taken along the cutting line VIII-VIII shown.

[0027] Figure 9 is a graph showing the relationship between the protruding amount of the fins and the resistance.

[0028] Figure 10 is a side view showing various dimensions of the fins provided in the upper section.

[0029] Figure 11 is a side view showing various dimensions of the fins provided in the lower section.

[0030] Figure 12 It is a cross-sectional view showing a modified example of the fin.

[0031] Figure 13 It is a cross-sectional view showing another modified example of the fin.

[0032] Figure 14 It is a perspective view of the fin of the second embodiment of the present invention.

[0033] Figure 15 It is Figure 14 a cross-sectional view taken along the cutting line XV-XV shown.

[0034] Figure 16 It is a graph showing the relationship between the angle θ and the area of the fin and the relationship between the angle θ and the frictional resistance.

[0035] Figure 17 It is a diagram showing the angle θ in the case where the lower surface of the fin is a curved surface.

[0036] Figure 18 It is a cross-sectional view of the fin of the third embodiment of the present invention.

[0037] Figure 19 It is a graph showing the relationship between the angle φ and the area of the fin and the relationship between the angle φ and the frictional resistance.

[0038] Figure 20 It is a diagram showing the angle φ in the case where the upper surface of the fin is a curved surface.

[0039] Figure 21 It is a view obtained by observing the fin of the fourth embodiment of the present invention from the bottom surface of the ship.

[0040] Figure 22 It is a graph showing the relationship between the angle α and the area of the fin and the relationship between the angle α and the frictional resistance.

[0041] Figure 23 It is a graph showing the relationship between the ship speed and the position of the bow. Detailed Embodiments

[0042] [First Embodiment]

[0043] Hereinafter, a wave-making reduction device of the first embodiment of the present invention and a ship equipped with the wave-making reduction device will be described with reference to the drawings.

[0044] As Figure 1 shown, the wave-making reduction device 20 includes two fins (protruding members) 21 and 22 provided on the ship side outer plate 11 on the bow 10A side of the ship 10.

[0045] The fins 21 and 22 are made of the same metallic material as the outer hull side plate 11, for example, and are fixed to the outer hull side plate 11 by welding.

[0046] The fins 21 and 22 are provided so as to extend in the direction from the bow 10A toward the stern 10B (hereinafter referred to as the "longitudinal direction").

[0047] In addition, the fins 21 and 22 are provided at positions above the full load waterline L1 of the ship 10 in the depth direction of the ship 10. Here, the full load waterline L1 is the maximum waterline allowed for the ship 10 loaded with cargo to sink in water.

[0048] Hereinafter, the fins 21 and 22 will be described in detail.

[0049] As Figures 2 to 5 shown, the fins 21 and 22 are respectively provided so as to protrude in the width direction of the ship 10 from the outer hull side plates 11 on both sides of the ship 10.

[0050] The fin 21 is a thin member that extends along the longitudinal direction of the ship 10 and has a predetermined thickness in the depth direction of the ship 10. The thickness of the fin 21 may be constant along the longitudinal direction of the ship 10 or may vary in a streamline shape. When the thickness of the fin 21 is constant, the fin 21 can be made of a simple plate material, so the manufacturing cost can be reduced. On the other hand, when the thickness of the fin 21 varies in a streamline shape (for example, in the shape of a wing), the air resistance and water resistance associated with the navigation of the ship 10 can be reduced.

[0051] The fin 22 is a thin member that extends along the longitudinal direction of the ship 10 and has a predetermined thickness in the depth direction of the ship 10. The thickness of the fin 22 may be constant along the longitudinal direction of the ship 10 or may vary in a streamline shape. When the thickness of the fin 22 is constant, the fin 22 can be made of a simple plate material, so the manufacturing cost can be reduced. On the other hand, when the thickness of the fin 22 varies in a streamline shape (for example, in the shape of a wing), the air resistance and water resistance associated with the navigation of the ship 10 can be reduced.

[0052] The fins 21 are paired on both sides of the outer hull side plate 11, and the fins 22 are also paired on both sides of the outer hull side plate 11. The paired fins 21 and the paired fins 22 are each provided at positions at substantially the same level in the depth direction of the ship 10. At this time, the fins 21 are located above the fins 22 in the depth direction of the ship 10. It should be noted that for the details of the installation positions of the fins 21 and 22, see the following description.

[0053] The fin 21 reduces the wave-making resistance acting on the ship 10 by pushing back the recirculation generated near the bow 10A when the ship 10 is navigating. For example, it is known that inFigure 6 In the ship 100 shown as a comparative example without fins and Figure 7 in the ship 10 provided with fins 21 shown, the height positions where the recirculation reaches are different. This is the effect brought about by the recirculation being pushed back by the fins 21 (so-called wave return).

[0054] The fins 21 particularly exhibit the wave return effect during low-speed navigation when the bow 10A sinks (refer to Figure 23 ).

[0055] The fins 22 reduce the wave-making resistance acting on the ship 10 by pushing back the recirculation generated near the bow 10A when the ship 10 is navigating.

[0056] The fins 22 particularly exhibit the wave return effect during high-speed navigation when the bow 10A floats (refer to Figure 23 ).

[0057] As Figure 8 shown, the protruding amount P2 of the fins 22 from the ship side outer plate 11 is smaller than the protruding amount P1 of the fins 21 from the ship side outer plate 11. Specifically, the protruding amount P2 of the fins 22 is preferably set to be 20% or more and 75% or less of the protruding amount P1 of the fins 21.

[0058] Regarding the relationship between the protruding amount P1 of the above-mentioned fins 21 and the protruding amount P2 of the fins 22, the inventors obtained the following insights through analysis and the like.

[0059] That is, as Figure 9 shown, when the protruding amount P1 of the fins 21 is set to 0.5% of Loa (the total length of the ship 10), and the protruding amount P2 of the fins 22 is set to 75% of the protruding amount P1 (equivalent to 0.375% of Loa), assuming that the fins 21 and 22 are submerged in water, the water resistance acting on the fins 22 (▲ shown in this figure) can be reduced to about 75% compared to the water resistance acting on the fins 21 (● shown in this figure). At this time, if the protruding amount P2 of the fins 22 is made larger than 75% of the protruding amount P1 of the fins 21, the effect of reducing the water resistance when submerged in water cannot be expected. Therefore, the upper limit value of the protruding amount P2 of the fins 22 is preferably 75% of the protruding amount P1 of the fins 21.

[0060] In addition, when the protrusion amount P1 of the fin 21 is set to 0.5% of Loa and the protrusion amount P2 of the fin 22 is set to 20% of the protrusion amount P1 (equivalent to 0.1% of Loa), assuming that the fins 21 and 22 are submerged in water, the water resistance acting on the fin 22 (■ shown in this figure) can be reduced to about 20% compared to the water resistance acting on the fin 21 (● shown in this figure). At this time, if the protrusion amount P2 of the fin 22 is set to less than 20% of the protrusion amount P1 of the fin 21, the effect of wave return brought by the fin 22 during high-speed navigation (when not submerged in water) cannot be expected. Therefore, the lower limit value of the protrusion amount P2 of the fin 22 is preferably 20% of the protrusion amount P1 of the fin 21.

[0061] The conditions for the above analysis are that Loa is 100 m, the thicknesses of the fins 21 and 22 are 0.1 m, and the ship speed is 10 m / s. In addition, in the above analysis, the protrusion amount P1 of the fin 21 is set to 0.5% of Loa, but in fact, it can also be 0.5% or less of Loa and can be appropriately changed according to the specifications of the ship 10, etc.

[0062] It should be noted that in the above description, it is assumed that the fin 21 is submerged in water, but this is not intended to mean that the fin 21 is submerged in water during actual navigation.

[0063] The protrusion amount P1 and the protrusion amount P2 are preferably set to be substantially constant along the length direction of the ship 10. That is, it is preferably configured that the outer shapes of the fins 21 and 22 change along the outer shape of the ship side outer plate 11.

[0064] As Figure 10 shown, the fin 21 configured as described above is provided in a specified range on the bow 10A side of the ship. Specifically, as follows.

[0065] That is, the front end 21A is provided at a position within 1% of Loa from the point D1A in the length direction of the ship 10 (X1A ≤ Loa × 1%), and is provided at a position within 3% of Loa from the full load waterline L1 in the depth direction of the ship 10 (Y1A ≤ Loa × 3%).

[0066] Here, the point D1A is the intersection point of the straight line L1A extending parallel to the full load waterline L1 from the front end 21A and the bow leading edge 11A of the ship 10.

[0067] In addition, the rear end 21B is provided at a position within (X1B ≤ Loa × 10%)10% of Loa from the point D1B in the length direction of the ship 10, and is provided at a position within 2% of Loa from the full load waterline L1 in the depth direction of the ship 10 (Y1B ≤ Loa × 2%).

[0068] Here, the point D1B is the intersection point of the straight line L1B extending parallel to the full-load waterline L1 from the rear end 21B and the bow leading edge 11A of the ship 10.

[0069] The fin 21 satisfies the above range, and the length along the longitudinal direction of the ship 10 is preferably more than 2 times the protruding amount P1, and more preferably more than 4 times.

[0070] It should be noted that, in Figure 10 , for simplicity of explanation, the illustration of the lower fin 22 is omitted.

[0071] As long as the fin 21 is within the above range, any size can be adopted, and it can be set at any position. For example, the length dimension of the fin 21 can be different from the length dimension of the fin 22, or the fin 21 and / or the fin 22 can be inclined in the side view of the ship 10 (e.g., Figure 5 ).

[0072] As the size of the fin 21, the following sizes are exemplified. That is, when the Loa is 200m, X1A = 2m, Y1A = 6m, X1B = 20m, and Y1B = 4m. It should be noted that the full-load waterline L1 is at a position 11m from the bottom surface.

[0073] As Figure 11 shown, the fin 22 configured as described above is provided in a specified range on the bow 10A side of the ship. Specifically, as follows.

[0074] That is, the front end 22A is provided in the longitudinal direction of the ship 10 at a position within 1% of the Loa from the point D2A (X2A ≤ Loa × 1%), and in the depth direction of the ship 10 at a position within 2% of the Loa from the full-load waterline L1 (Y1B ≤ Loa × 2%).

[0075] Here, the point D2A is the intersection point of the straight line L2A extending parallel to the full-load waterline L1 from the front end 22A and the bow leading edge 11A of the ship 10.

[0076] In addition, the rear end 22B is provided in the longitudinal direction of the ship 10 at a position within 10% of the Loa from the point D2B (X2B ≤ Loa × 10%), and in the depth direction of the ship 10 at a position within 1% of the Loa from the full-load waterline L1 (Y2B ≤ Loa × 1%).

[0077] Here, the point D2B is the intersection point of the straight line L2B extending parallel to the full-load waterline L1 from the rear end 22B and the bow leading edge 11A of the ship 10.

[0078] The fin 22 satisfies the above range, and the length along the longitudinal direction of the ship 10 is preferably more than 2 times, more preferably more than 4 times, of the protruding amount P1.

[0079] It should be noted that, in Figure 11 , for simplicity of illustration, the illustration of the fin 21 in the upper section is omitted.

[0080] If the fin 22 is within the above range, it can adopt any size, and can be set at any position. For example, the length dimension of the fin 21 can be different from that of the fin 22, or the fin 21 and / or the fin 22 can be inclined in the side view of the ship 10 (for example Figure 5 ).

[0081] As the size of the fin 22, the following sizes are exemplified. That is, when the Loa is 200 m, X2A = 2 m, Y2A = 4 m, X2B = 20 m, and Y2B = 2 m. It should be noted that the full-load waterline L1 is at the position 11 m from the bottom surface.

[0082] The fins 21 and 22 configured as above can also be arranged as Figure 8 shown, in a manner parallel to each other along the width direction of the ship 10 and protruding in the horizontal direction, or can be arranged as Figure 12 shown, in a manner parallel to each other along the width direction of the ship 10 and protruding while being inclined downward with respect to the horizontal direction. When the fins 21 and 22 are inclined with respect to the horizontal direction, it is preferably 45° or less with respect to the horizontal direction.

[0083] According to the present embodiment, the following effects are achieved.

[0084] There are provided plate-shaped fins 21 and 22 that protrude from the ship side outer plate 11 along the width direction of the ship 10 on the bow 10A side of the ship 10 and extend along the longitudinal direction of the ship 10. The fins 21 and 22 are arranged at a position above the full-load waterline L1 in the depth direction of the ship 10. Therefore, the fins 21 and 22 can suppress the wave-making in all ranges of ship speeds and reduce the wave-making resistance.

[0085] In addition, the fin 21 is arranged above the fin 22 in the depth direction of the ship 10, and the protruding amount P2 of the fin 22 is smaller than the protruding amount P1 of the fin 21. Therefore, even when the fin 22 is submerged in water during low-speed navigation when the bow 10A side sinks, the resistance received by the fin 22 from the water can be reduced. Thus, the resistance acting on the hull of the ship 10 can be reduced.

[0086] In addition, the protruding amount P1 of the fin 21 is set to an amount within 0.5% of Loa, and the protruding amount P2 of the fin 22 is set to an amount of 20% or more and 75% or less of the protruding amount P1 of the fin 21. Therefore, the protruding amount P1 of the fin 21 and the protruding amount P2 of the fin 22 can be determined based on Loa.

[0087] In addition, the front ends 21A, 22A of the fins 21, 22 are arranged at positions within 1% of Loa from the bow leading edge 11A in the longitudinal direction, and the rear ends 21B, 22B of the fins 21, 22 are arranged at positions within 10% of Loa from the bow leading edge 11A in the longitudinal direction. Therefore, the dimensions (range) of the fins 21, 22 along the longitudinal direction of the ship 10 can be determined based on Loa.

[0088] In addition, the front end 21A of the fin 21 is arranged at a position within 3% of Loa from the full load waterline L1 in the depth direction, and the rear end 21B of the fin 21 is arranged at a position within 2% of Loa from the full load waterline L1 in the depth direction. Therefore, the height position (range) of the fin 21 arranged at the uppermost part can be determined based on Loa.

[0089] In addition, the front end 22A of the fin 22 is arranged at a position within 2% of Loa from the full load waterline L1 in the depth direction, and the rear end 22B of the fin 22 is arranged at a position within 1% of Loa from the full load waterline L1 in the depth direction. Therefore, the height position (range) of the fin 22 arranged at the lowermost part can be determined based on Loa.

[0090] In addition, the fins 21, 22 are arranged parallel to each other in the width direction and protrude horizontally from the ship side outer plate 11. Therefore, even if the fins 21, 22 are submerged in water, the resistance received by the fins 21, 22 from the water can be reduced. Thereby, the resistance acting on the hull of the ship 10 can be reduced.

[0091] In addition, the fins 21, 22 may be arranged parallel to each other in the width direction and protrude from the ship side outer plate 11 in a manner inclined downward with respect to the horizontal direction. In this case, the effect of returning the waves caused by the fins 21, 22 can be improved.

[0092] It should be noted that in the present embodiment, it is also possible to Figure 13 as shown, set the cross-sectional shapes of the fins 21, 22 to be wedge-shaped. Thereby, the strength of the fins 21, 22 can be increased.

[0093] In addition, other fins (fins paired on both sides of the ship side outer plate 11) may be added to the fins 21, 22 to form a structure with three or more stages.

[0094] [Second Embodiment]

[0095] Hereinafter, the wave-making reduction device according to the second embodiment of the present invention will be described with reference to the accompanying drawings.

[0096] It should be noted that the wave-making reduction device of the present embodiment has different shapes of the fins 21 and 22 from those of the first embodiment, and the other structures are the same. Therefore, in the following description, the same reference numerals are given to the same structures as those of the first embodiment and their descriptions are omitted.

[0097] In addition, in the following description, the fin 21 is taken as an example, but the fin 22 can also adopt the same structure.

[0098] As Figure 14 and Figure 15 shown, the angle formed by the lower surface 21C of the fin 21 and the ship side outer plate 11 connected to the lower surface 21C at the central position in the extending direction of the fin 21 is set as θ. That is, when the intersection point of the lower surface 21C and the ship side outer plate 11 is set as point CA, the angle formed by the lower surface 21C and the ship side outer plate 11 with point CA as the center is set as θ. At this time, θ is set to be more than 135° and less than 165°.

[0099] By configuring in this way, the following effects can be obtained.

[0100] That is, when the lower surface 21C is on the horizontal plane (illustrated by the reference numeral 21Ch in Figure 15 ), when the imaginary intersection point of the horizontal lower surface 21Ch and the ship side outer plate 11 is set as point CAh, the area AC of the lower surface 21C can be made smaller than the total area of the area of the horizontal lower surface 21Ch and the area of the ship side outer plate 11 from point CAh to point CA (hereinafter, referred to as "imaginary area A0C").

[0101] When deriving this, the inventors performed an analysis of comparing the imaginary area A0C and the area AC when θ is changed.

[0102] As a result, as Figure 16 shown, it can be known that the area AC is smaller than the imaginary area A0C when θ exceeds 120° (the reduced area is set as ΔAC).

[0103] At this time, the frictional resistance Rf0 that the fin 21 receives from the wave with the imaginary area A0C is obtained using the following mathematical formula (1), the frictional resistance reduction amount ΔRf due to the reduced area ΔAC is obtained using the mathematical formula (2), and ΔRf / Rf0 is calculated.

[0104] [Mathematical formula 1]

[0105]

[0106] Herein,

[0107] Re: Reynolds number

[0108] ρ: Seawater density

[0109] A: Hypothetical area.

[0110] [Mathematical formula 2]

[0111]

[0112] Herein,

[0113] Re: Reynolds number

[0114] ρ: Seawater density

[0115] ΔA: Reduced area.

[0116] As a result, as Figure 16 shown, it can be seen that ΔRf / Rf0 decreases by more than 10% when 135° < θ < 165°, and shows a minimum value (-14%) when θ = 150°.

[0117] It should be noted that the conditions for the above analysis are that Loa is 200 m, the protrusion amount of the fin 21 is 1 m, the length of the fin 21 is 18 m, the ship speed is 20 kn, and the bow flare angle is 30°.

[0118] According to the above results, by setting 135° < θ < 165°, the effect of reducing the wave-making resistance can be maintained, and the frictional resistance received by the lower surface 21C from the waves can be reduced.

[0119] [Modified example]

[0120] As Figure 17 shown, the lower surface 21C can also be a curved surface protruding upward.

[0121] At this time, the starting point (lower starting point) of the lower surface 21C of the fin 21 is set as point CA, and the position of the lower surface 21C along the horizontal direction at 50% of the protrusion amount P1 from point CA is set as point CB. In this case, the angle formed by the tangent of the ship side outer plate 11 at point CA and the tangent of the lower surface 21C at point CB can be set as θ. Herein, the range that θ can take is the same as above.

[0122] According to this embodiment, the following effects are achieved.

[0123] Since θ is set to be more than 135° and less than 165°, the effect of reducing the wave-making resistance can be maintained, and an increase in the area of the lower surface 21C can be suppressed. Thereby, the effect of reducing the wave-making resistance can be maintained, and the frictional resistance received by the lower surface 21C from the waves can be reduced.

[0124] It should be noted that this embodiment can also be applied independently of the first embodiment.

[0125] [Third Embodiment]

[0126] Hereinafter, the wave-making reduction device according to the third embodiment of the present invention will be described with reference to the drawings.

[0127] It should be noted that the shapes of the fins 21 and 22 of the wave-making reduction device of this embodiment are different from those of the first embodiment and the second embodiment, and other structures are the same. Therefore, in the following description, the same reference numerals are given to the same structures as those of the first embodiment and the second embodiment, and their descriptions are omitted.

[0128] In addition, in the following description, the fin 21 is taken as an example, but the fin 22 can also adopt the same structure.

[0129] As Figure 18 shown, the angle formed by the upper surface 21D of the fin 21 and the ship side outer plate 11 connected to the upper surface 21D at the central position in the extending direction of the fin 21 is set as φ. That is, when the intersection point of the upper surface 21D and the ship side outer plate 11 is set as point DA, the angle formed by the upper surface 21D and the ship side outer plate 11 with point DA as the center is set as φ. At this time, φ is set to be more than 90° and less than 160°.

[0130] By configuring in this way, the following effects can be obtained.

[0131] That is, when the upper surface 21CD is on the horizontal plane (illustrated by the reference numeral 21Dh in Figure 18 ), when the imaginary intersection point of the horizontal upper surface 21Dh and the ship side outer plate 11 is set as point DAh, the area AD of the upper surface 21D can be made smaller than the total area of the area of the horizontal upper surface 21Dh and the area of the ship side outer plate 11 from point DAh to point DA (hereinafter referred to as "imaginary area A0D").

[0132] When deriving this, the inventors conducted an analysis of comparing the imaginary area A0D and the area AD when φ changes.

[0133] As a result, as Figure 19 shown, it can be known that the area AD is smaller than the imaginary area A0D when φ exceeds 60° (the reduced area is set as ΔAD).

[0134] At this time, the frictional resistance Rf0 that the fin 21 receives from the wave with the imaginary area A0D is obtained using the above mathematical formula (1), the frictional resistance reduction amount ΔRf due to the reduced area ΔAD is obtained using the mathematical formula (2), and ΔRf / Rf0 is calculated.

[0135] As a result, as Figure 19 shown, ΔRf / Rf0 decreases by more than 25% when 90° < φ < 160°, and shows a minimum value (-40%) when φ = 130°.

[0136] It should be noted that the conditions for the above analysis are that Loa is 200 m, the protrusion amount of the fin 21 is 1 m, the length of the fin 21 is 18 m, the ship speed is 20 kn, and the bow flare angle is 30°.

[0137] Based on the above results, by setting 90° < φ < 160°, the effect of reducing the wave-making resistance can be maintained, and the frictional resistance that the upper surface 21D receives from the waves can be reduced.

[0138] [Modification Example]

[0139] As Figure 20 shown, the upper surface 21D may also be a downwardly convex curved surface.

[0140] At this time, the starting point (upper starting point) of the upper surface 21D of the fin 21 is set as point DA, and the position of the upper surface 21D that is 50% of the protrusion amount P1 along the horizontal direction from point DA is set as point DB. In this case, the angle formed by the tangent of the ship side outer plate 11 at point DA and the tangent of the upper surface 21D at point DB can be set as φ. Here, the range that θ can take is the same as above.

[0141] According to the present embodiment, the following effects are achieved.

[0142] Since φ is set to be more than 90° and less than 160°, the effect of reducing the wave-making resistance can be maintained, and an increase in the area of the upper surface 21D can be suppressed. Thus, the effect of reducing the wave-making resistance can be maintained, and the frictional resistance that the upper surface 21D receives from the waves when the fin 21 is submerged in water can be reduced.

[0143] It should be noted that the present embodiment can also be applied independently of at least any one of the first embodiment and the second embodiment.

[0144] [Fourth Embodiment]

[0145] Hereinafter, the wave-making reduction device according to the fourth embodiment of the present invention will be described with reference to the drawings.

[0146] It should be noted that the wave-making reduction device of the present embodiment has different shapes of the fins 21 and 22 from those of the first to third embodiments, and the other structures are the same. Therefore, in the following description, the same reference numerals are given to the same structures as those of the first to third embodiments and their description is omitted.

[0147] In addition, in the following description, the fin 21 is taken as an example, but the fin 22 can also adopt the same structure.

[0148] As Figure 21 shown, when observing the fin 21 from the bottom surface of the ship 10, the intersection point of the center line C1 in the protruding direction of the fin 21 (i.e., the width direction of the fin 21) and the rear end edge (edge part) 21Ba of the fin 21 is set as point E. In this case, the angle formed by the tangent line of the rear end edge 21Ba at point E and the plane perpendicular to the length direction of the ship 10 is set as α. At this time, α is set to be more than 60° and less than 90°.

[0149] By configuring in this way, the following effects can be obtained.

[0150] That is, the area AE of the lower surface 21C can be made smaller than the area of the lower surface 21C in the case of α = 0° (hereinafter referred to as "imaginary area A0E").

[0151] It should be noted that the case of α = 0° is the state where the rear end edge 21Ba is parallel to the plane perpendicular to the length direction of the ship 10.

[0152] In order to derive it, the inventors performed an analysis of comparing the imaginary area A0E and the area AE when α is changed.

[0153] As a result, as Figure 22 shown, it can be seen that the area AE becomes smaller with respect to the imaginary area A0E by setting α (the reduced area is set as ΔAE).

[0154] At this time, the frictional resistance Rf0 that the fin 21 receives from the wave with the imaginary area A0E is obtained using the above mathematical formula (1), and the frictional resistance reduction amount ΔRf due to the reduced area ΔAE is obtained using the mathematical formula (2), and ΔRf / Rf0 is calculated.

[0155] As a result, as Figure 22 shown, it can be seen that ΔRf / Rf0 decreases sharply when α exceeds 60°. However, if α is set to 90° or more, the rear end edge 21Ba is substantially parallel to the streamline, and the effect of reducing the wave-making resistance decreases.

[0156] It should be noted that the conditions for the above analysis are that Loa is 200 m, the protruding amount of the fin 21 is 1 m, the length of the fin 21 is 18 m, the ship speed is 20 kn, and the bow flare angle is 30°.

[0157] Based on the above results, by setting 60° < α < 90°, the effect of reducing the wave-making resistance can be maintained, and the frictional resistance that the lower surface 21C receives from the wave can be reduced.

[0158] It should be noted that this embodiment can also be applied independently of at least any one of the first to third embodiments.

[0159] The wave-making reduction device of each embodiment described as above and the ship equipped with the wave-making reduction device are grasped as follows, for example.

[0160] That is, the wave-making reduction device (20) of an embodiment of the present invention includes a plurality of protruding members (21, 22) that protrude from the ship side outer plate (11) along the width direction of the ship (10) on the bow (10A) side of the ship (10) and extend from the bow (10A) toward the stern (10B). The plurality of protruding members (21, 22) are disposed at a position above the full load waterline (L1) in the depth direction of the ship (10). One protruding member (21) is disposed above the other protruding member (22) in the depth direction of the ship (10), and the protruding amount (P2) of the other protruding member (22) is set to be smaller than the protruding amount (P1) of the one protruding member (21).

[0161] According to the wave-making reduction device (20) of this solution, it includes a plurality of plate-shaped protruding members (21, 22) that protrude from the ship side outer plate (11) along the width direction of the ship (10) on the bow (10A) side of the ship (10) and extend from the bow (10A) toward the stern (10B). The plurality of protruding members (21, 22) are disposed at a position above the full load waterline (L1) in the depth direction of the ship (10). Therefore, the wave-making can be suppressed by the plurality of protruding members (21, 22) at all ranges of ship speeds, and the wave-making resistance can be reduced.

[0162] In addition, one protruding member (21) is disposed above the other protruding member (22) in the depth direction of the ship (10), and the protruding amount (P2) of the other protruding member (22) is set to be smaller than the protruding amount (P1) of the one protruding member (21). Therefore, even when the lower protruding member (the other protruding member (22)) is submerged in water during low-speed navigation when the bow (10A) side sinks, the resistance received by the other protruding member (22) from the water can be reduced. Thus, the resistance acting on the hull of the ship (10) can be reduced.

[0163] In addition, based on the wave-making reduction device (20) of an embodiment of the present invention, the protruding amount (P1) of the one protruding member (21) is set to an amount within 0.5% of Loa, and the protruding amount (P2) of the other protruding member (22) is set to an amount of 20% or more and 75% or less of the protruding amount (P1) of the one protruding member (21).

[0164] In the wave-making reduction device (20) according to this solution, the protruding amount (P1) of one protruding member (21) is set to an amount within 0.5% of Loa, and the protruding amount (P2) of the other protruding members (22) is set to an amount of 20% or more and 75% or less of the protruding amount (P1) of one protruding member (21). Therefore, the protruding amount (P1) of one protruding member (21) and the protruding amount (P2) of the other protruding members (22) can be determined based on Loa.

[0165] In addition, based on the wave-making reduction device (20) of an embodiment of the present invention, the ends (21A, 22A) on the bow (10A) side of the plurality of protruding members (21, 22) are arranged at positions within 1% of Loa from the leading edge (11A) of the bow (10A) in the longitudinal direction of the ship (10), and the ends (21B, 22B) on the stern side of the plurality of protruding members (21, 22) of the ship (10) are arranged at positions within 10% of Loa from the leading edge (11A) of the bow (10A) in the longitudinal direction.

[0166] In the wave-making reduction device (20) according to this solution, the ends (21A, 22A) on the bow (10A) side of the plurality of protruding members (21, 22) are arranged at positions within 1% of Loa from the leading edge (11A) of the bow (10A) in the longitudinal direction, and the ends (21B, 22B) on the stern side of the plurality of protruding members (21, 22) of the ship (10) are arranged at positions within 10% of Loa from the leading edge (11A) of the bow (10A) in the longitudinal direction. Therefore, the dimensions (range) of the plurality of protruding members (21, 22) along the longitudinal direction of the ship (10) can be determined based on Loa.

[0167] In addition, based on the wave-making reduction device (20) of an embodiment of the present invention, the one protruding member (21) is set as the protruding member among the plurality of protruding members (21, 22) that is arranged at the uppermost position in the depth direction of the ship (10). The end (21A) on the bow (10A) side of the one protruding member (21) is arranged at a position within 3% of Loa from the full load waterline (L1) in the depth direction, and the end (21B) on the stern side of the one protruding member (21) is arranged at a position within 2% of Loa from the full load waterline (L1) in the depth direction.

[0168] According to the wave-making reduction device (20) of this solution, a protruding member (21) is set as the protruding member that is arranged at the uppermost position in the depth direction of the ship (10) among the plurality of protruding members (21, 22). The end portion (21A) on the bow (10A) side of a protruding member (21) is arranged at a position within 3% of Loa from the full-load waterline (L1) in the depth direction, and the end portion (21B) on the stern side of a protruding member (21) is arranged at a position within 2% of Loa from the full-load waterline (L1) in the depth direction. Therefore, the height position (range) of the protruding member (21) arranged at the uppermost position can be determined based on Loa.

[0169] In addition, based on the wave-making reduction device (20) of an embodiment of the present invention, the other protruding member (22) is set as the protruding member that is arranged at the lowermost position in the depth direction of the ship (10) among the plurality of protruding members (21, 22). The end portion (22A) on the bow (10A) side of the other protruding member (22) is arranged at a position within 2% of Loa from the full-load waterline (L1) in the depth direction, and the end portion (22B) on the stern side of the other protruding member (22) is arranged at a position within 1% of Loa from the full-load waterline (L1) in the depth direction.

[0170] According to the wave-making reduction device (20) of this solution, the other protruding member (22) is set as the protruding member that is arranged at the lowermost position in the depth direction of the ship (10) among the plurality of protruding members (21, 22). The end portion (22A) on the bow (10A) side of the other protruding member (22) is arranged at a position within 2% of Loa from the full-load waterline (L1) in the depth direction, and the end portion (22B) on the stern side of the other protruding member (22) is arranged at a position within 1% of Loa from the full-load waterline (L1) in the depth direction. Therefore, the height position (range) of the protruding member (22) arranged at the lowermost position can be determined based on Loa.

[0171] In addition, based on the wave-making reduction device (20) of an embodiment of the present invention, the plurality of protruding members (21, 22) are arranged parallel to each other along the width direction and protrude horizontally from the ship side outer plate (11).

[0172] According to the wave-making reduction device (20) of this solution, the plurality of protruding members (21, 22) are arranged parallel to each other along the width direction and protrude horizontally from the ship side outer plate (11). Therefore, even if the protruding members (21, 22) are submerged in water, the resistance received by the protruding members (21, 22) from the water can be reduced. Thus, the resistance acting on the hull of the ship (10) can be reduced.

[0173] Further, based on the wave-making reduction device (20) according to an embodiment of the present invention, a plurality of the protruding members (21, 22) are arranged parallel to each other in the width direction and protrude from the ship side outer plate (11) in a manner inclined downward with respect to the horizontal direction.

[0174] In the wave-making reduction device (20) according to this solution, a plurality of protruding members (21, 22) are arranged parallel to each other in the width direction and protrude from the ship side outer plate (11) in a manner inclined downward with respect to the horizontal direction. Therefore, the effect of returning the waves brought by the protruding members (21, 22) can be improved.

[0175] Further, based on the wave-making reduction device (20) according to an embodiment of the present invention, a plurality of the protruding members (21, 22) are formed in a wedge shape in a cross-section view.

[0176] In the wave-making reduction device (20) according to this solution, a plurality of protruding members (21, 22) are formed in a wedge shape in a cross-section view. Therefore, the strength of the protruding members (21, 22) can be improved.

[0177] Further, based on the wave-making reduction device (20) according to an embodiment of the present invention, in the protruding member (21), the angle (θ) formed by the lower surface (21C) of the protruding member (21) and the ship side outer plate (11) is set to be more than 135° and less than 165°.

[0178] In the wave-making reduction device (20) according to this solution, in the protruding member (21), the angle (θ) formed by the lower surface (21C) of the protruding member (21) and the ship side outer plate (11) is set to be more than 135° and less than 165°. Therefore, the effect of reducing the wave-making resistance can be maintained, and an increase in the area of the lower surface (21C) can be suppressed. Thereby, the effect of reducing the wave-making resistance can be maintained, and the frictional resistance borne by the lower surface (21C) from the waves can be reduced.

[0179] Further, based on the wave-making reduction device (20) according to an embodiment of the present invention, when the intersection point of the lower surface (21C) of the protruding member (21) and the ship side outer plate (11) is set as the lower starting point (CA) of the protruding amount (P1), the angle (θ) formed by the tangent line of the lower surface (21C) at the position of 50% of the protruding amount (P1) starting from the lower starting point (CA) and the tangent line of the ship side outer plate (11) at the lower starting point (CA) is set to be more than 135° and less than 165°.

[0180] For the wave-making reduction device (20) according to this solution, when the intersection point of the lower surface (21C) of the protruding member (21) and the ship side outer plate (10) is set as the lower starting point (CA) of the protruding amount (P1), the angle (θ) formed by the tangent line of the lower surface (21C) at the position of 50% of the protruding amount (P1) starting from the lower starting point (CA) and the tangent line of the ship side outer plate (11) at the lower starting point (CA) exceeds 135° and is less than 165°. Therefore, even when the lower surface (21C) is a curved surface, the effect of reducing the wave-making resistance can be maintained, and the frictional resistance that the lower surface (21C) receives from the wave can be reduced.

[0181] In addition, based on the wave-making reduction device (20) of an embodiment of the present invention, in the protruding member (21), the angle (φ) formed by the upper surface (21D) of the protruding member (21) and the ship side outer plate (11) is set to exceed 90° and be less than 160°.

[0182] For the wave-making reduction device (20) according to this solution, in the protruding member (21), the angle (φ) formed by the upper surface (21D) of the protruding member (21) and the ship side outer plate (11) is set to exceed 90° and be less than 160°. Therefore, an increase in the area of the upper surface (21D) can be suppressed. Thereby, the frictional resistance that the upper surface (21D) of the protruding member (21) receives from the wave when the protruding member (21) is submerged in water can be reduced.

[0183] In addition, based on the wave-making reduction device (20) of an embodiment of the present invention, when the intersection point of the upper surface (21D) of the protruding member (21) and the ship side outer plate (11) is set as the upper starting point (DA) of the protruding amount (P1), the angle (φ) formed by the tangent line of the upper surface (21D) at the position of 50% of the protruding amount (P1) starting from the upper starting point (DA) and the tangent line of the ship side outer plate (11) at the upper starting point (DA) is set to exceed 90° and be less than 160°.

[0184] For the wave-making reduction device (20) according to this solution, when the intersection point of the upper surface (21D) of the protruding member (21) and the ship side outer plate (11) is set as the upper starting point (DA) of the protruding amount (P1), the angle (φ) formed by the tangent line of the upper surface (21D) at the position of 50% of the protruding amount (P1) starting from the upper starting point (DA) and the tangent line of the ship side outer plate (11) at the upper starting point (DA) exceeds 90° and is less than 160°. Therefore, even when the upper surface (21D) is a curved surface, the frictional resistance that the upper surface (21D) of the protruding member (21) receives from the wave when the protruding member (21) is submerged in water can be reduced.

[0185] In addition, based on the wave-making reduction device (20) according to an embodiment of the present invention, when observing the ship (10) from the bottom surface, the angle (α) formed by the tangent of the edge portion (21Ba) at the intersection of the center line (C1) in the protruding direction of the protruding member (21) and the edge portion (21Ba) of the protruding member (21) on the stern (10B) side with the plane perpendicular to the longitudinal direction of the ship (10) is set to be more than 60° and less than 90°.

[0186] According to the wave-making reduction device (20) of this solution, when observing the ship (10) from the bottom surface, the angle (α) formed by the tangent of the edge portion (21Ba) at the intersection of the center line (C1) in the protruding direction of the protruding member (21) and the edge portion (21Ba) of the protruding member (21) on the stern (10B) side with the plane perpendicular to the longitudinal direction of the ship (10) is set to be more than 60° and less than 90°. Therefore, the effect of reducing wave-making resistance can be maintained, and the frictional resistance borne by the edge portion (21Ba) of the protruding member (21) from the wave can be reduced.

[0187] In addition, the wave-making reduction device (20) according to an embodiment of the present invention includes a protruding member (21) that protrudes from the ship side outer plate (11) in the width direction of the ship (10) on the bow (10A) side of the ship (10) and extends from the bow (10A) toward the stern (10B). In the protruding member (21), the angle (θ) formed by the lower surface (21C) of the protruding member (21) and the ship side outer plate (11) is set to be more than 135° and less than 165°.

[0188] In addition, based on the wave-making reduction device (20) according to an embodiment of the present invention, when the intersection of the lower surface (21C) of the protruding member (21) and the ship side outer plate (11) is set as the lower starting point (CA) of the protruding amount (P1), the angle (θ) formed by the tangent of the lower surface (21C) at the position of 50% of the protruding amount (P1) from the lower starting point (CA) and the tangent of the ship side outer plate (11) at the lower starting point (CA) is set to be more than 135° and less than 165°.

[0189] In addition, a ship (10) according to an embodiment of the present invention includes the wave-making reduction device (20) described in any one of the above.

[0190] Description of Reference Numerals

[0191] 10 Ship

[0192] 10A Bow

[0193] 10B Stern

[0194] 11 Ship Side Outer Plate

[0195] 11A Bow leading edge

[0196] 20 Wave-making reduction device

[0197] 21 Fin (a protruding member)

[0198] 21A Front end

[0199] 21B Rear end

[0200] 21Ba Rear end edge (edge part)

[0201] 21C Lower surface

[0202] 21D Upper surface

[0203] 22 Fin (other protruding member)

[0204] 22A Front end

[0205] 22B Rear end

[0206] 100 Ship of the comparative example.

Claims

1. A wave-making reduction device, wherein, the wave-making reduction device includes a plurality of protruding members that protrude from the ship side outer plate along the width direction of the ship on the bow side of the ship and extend from the bow toward the stern, the plurality of protruding members are arranged at positions above the full load waterline in the depth direction of the ship, one protruding member is arranged above other protruding members in the depth direction, the protruding amount of the other protruding members is set to be smaller than the protruding amount of the one protruding member, the protruding amount of the one protruding member is set to an amount within 0.5% of Loa, that is, the total length of the ship, the protruding amount of the other protruding members is set to an amount of 20% or more and 75% or less of the protruding amount of the one protruding member, the protruding amount of the one protruding member and the protruding amount of the other protruding members are set to be substantially constant amounts along the length direction of the ship.

2. The wave-making reduction device according to claim 1, wherein, the bow side ends of the plurality of protruding members are arranged at positions within 1% of Loa from the bow front edge in the length direction of the ship, the stern side ends of the plurality of protruding members on the ship are arranged at positions within 10% of Loa from the bow front edge in the length direction.

3. The wave-making reduction device according to claim 1, wherein, the one protruding member is set to be the protruding member arranged at the uppermost position in the depth direction among the plurality of protruding members, the bow side end of the one protruding member is arranged at a position within 3% of Loa from the full load waterline in the depth direction, the stern side end of the one protruding member is arranged at a position within 2% of Loa from the full load waterline in the depth direction.

4. The wave-making reduction device according to claim 3, wherein, the other protruding member is set to be the protruding member arranged at the lowermost position in the depth direction among the plurality of protruding members, the bow side end of the other protruding member is arranged at a position within 2% of Loa from the full load waterline in the depth direction, the stern side end of the other protruding member is arranged at a position within 1% of Loa from the full load waterline in the depth direction.

5. The wave-making reduction device according to any one of claims 1 to 4, wherein, the plurality of protruding members are arranged parallel to each other along the width direction and protrude horizontally from the ship side outer plate.

6. The wave-making reduction device according to any one of claims 1 to 4, wherein, the plurality of protruding members are arranged parallel to each other along the width direction and protrude from the ship side outer plate in a manner inclined downward relative to the horizontal direction.

7. The wave-making reduction device according to any one of claims 1 to 4, wherein, the plurality of protruding members are set to be wedge-shaped in cross-section.

8. The wave-making reduction device according to claim 1, wherein, In the protruding member, the angle formed by the lower surface of the protruding member and the outer hull plate is set to be more than 135° and less than 165°.

9. The wave-making reduction device according to claim 8, wherein when the intersection point of the lower surface of the protruding member and the outer hull plate is set as the lower starting point of the protruding amount, the angle formed by the tangent line of the lower surface at the position of 50% of the protruding amount from the lower starting point and the tangent line of the outer hull plate at the lower starting point is set to be more than 135° and less than 165°.

10. The wave-making reduction device according to any one of claims 1, 8, and 9, wherein in the protruding member, the angle formed by the upper surface of the protruding member and the outer hull plate is set to be 90° or more and 160° or less.

11. The wave-making reduction device according to claim 10, wherein when the intersection point of the upper surface of the protruding member and the outer hull plate is set as the upper starting point of the protruding amount, the angle formed by the tangent line of the upper surface at the position of 50% of the protruding amount from the upper starting point and the tangent line of the outer hull plate at the upper starting point is set to be more than 90° and less than 160°.

12. The wave-making reduction device according to any one of claims 1, 8, and 9, wherein when observing the ship from the bottom surface, the angle formed by the tangent line of the edge portion at the intersection point of the center line in the protruding direction of the protruding member and the edge portion of the protruding member on the stern side and the plane perpendicular to the longitudinal direction of the ship is set to be more than 60° and less than 90°.

13. A wave-making reduction device, wherein the wave-making reduction device includes a protruding member that protrudes from the outer hull plate in the width direction of the ship on the bow side of the ship and extends from the bow toward the stern, in the protruding member, the angle formed by the lower surface of the protruding member and the outer hull plate is set to be more than 135° and less than 165°, when the intersection point of the lower surface of the protruding member and the outer hull plate is set as the lower starting point of the protruding amount, the angle formed by the tangent line of the lower surface at the position of 50% of the protruding amount from the lower starting point and the tangent line of the outer hull plate at the lower starting point is set to be more than 135° and less than 165°.

14. A ship, wherein the ship is equipped with the wave-making reduction device according to any one of claims 1 to 13.

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