JP2007069835A - Vessel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vessel capable of reducing wave making resistance in sailing in ordinary water and an in-wave resistance increase in sailing in an ocean wave by making a vessel form with water level elevation near a stagnation point at a bow taken into account. <P>SOLUTION: In the bows of the vessels 1, 1A, a full load draft line valve 10 where at least a part of the valve 10 is submerged in sailing in ordinary water in a state of a full load draft df is provided so that a central position Zbc in the vertical direction of the full load draft line valve 10 is above the full load draft line df of the vessels 1, 1A, and a water cut member 20 having a wedge shaped horizontal cross section is provided between the upper part of the full load draft line valve 10 and a bow flare 30. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a ship capable of improving propulsion performance during full-water navigation and wave navigation in a full state.

  Recently, in order to improve the propulsion performance of large ships such as large tankers, bulk carriers, ore carriers, crushing resistance due to wave collapse at the rounded bow and reflected waves to the front of the ship or by hull movement The increase in resistance in the waves caused by wave formation has attracted attention, and various bow shapes and bow appendages have been proposed to reduce these resistances.

  As one of these, in order to reduce the resistance to breakage and wave reflection both in the flat water (still water) and in the waves when sailing in full load, in a hypertrophic ship, the bow flare of the hull and the bow valve A large-sized fertilizer ship with a device for reducing drag and a means for improving the propulsion performance in waves has been proposed in which a bow appendage that protrudes acutely forward as viewed from the horizontal plane is attached to the front of the bow of the full waterline between (For example, see Patent Document 1 and Patent Document 2.)

  However, with this wedge-shaped bow appendage and means for improving propulsion performance in the waves, the incident wave and the wave generated by the ship itself can be divided into left and right, but the shape of the wedge is simple, so the water surface of the bow There is a problem that the wave-making resistance created by the hull itself due to the rise cannot be sufficiently reduced, and a problem that the flow is easily separated from an oblique flow or incident wave.

  In addition, when applying to an actual ship, this wedge-shaped bow appendage is provided over the upper and lower regions including the full load waterline, so that the ship's reference, the strength of structure, etc., used as a reference for calculating ship Since the representative length (water line length (LWL), length between perpendiculars (Lpp), total length (Lo), etc.) is increased by the wedge-shaped bow appendage, the length is based on these lengths. This greatly affects the basic design and structural design performed in this way, and there is a problem that design calculation is re-executed and, in some cases, a large design change occurs.

  On the other hand, as a result of observing the state of the aquarium experiment and the actual ship's voyage, the present inventors are important to consider the rise in the water surface around the stagnation point O of the bow at the time of sailing in flat water, It was found that by adopting the bow shape considering this rise in water surface, the resistance to wave formation during navigating in flat water and the increase in wave resistance during navigating in waves can be reduced.

That is, as shown in FIG. 10, when the ship is sailing in flat water, the bow and the water have a relative traveling speed Vs, and when viewed in a coordinate system fixed on the ship side, Water flows into the bow at a flow velocity Vs. Therefore, in a blunt enlarged ship with a rounded and thick bow, the water flow velocity Vo becomes zero at the stagnation point O on the center line (CL) of the bow, so the density of water is ρ and the gravitational acceleration is g Then, the relationship between the water head h2 at the stagnation point O and the distant water head hs is ρ × g × h2 + ρ × Vo ² / (2 × g) = ρ × g × hs + ρ × Vs ² / by Bernoulli's theorem. (2 × g), and the water head h2 at the stagnation point O is h2 = Vs ² / (2 × g) −Vo ² / (2 × g) + hs. Here, when Vo = 0 and hs = 0, h2 = Vs ² / (2 × g). For example, in the case of a ship having a boat speed of 15 kt (knots), the water head h2 is Vs = 7.72 m / s, which is 3.0 m.

Accordingly, the head h2 indicating the amount of water rising at the stagnation point O of the bow is Vs ² / (2 × g). The water surface rises to the vicinity of (Z2 line). In other words, the actual submerged portion in the vicinity of the bow reaches the vicinity of the position Z2 that is higher than the full load water line df by the water head h2.

  On the other hand, in a conventional large tanker or bulk carrier, a bow valve (Bulbous Bow) is provided at the bow in order 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.

  This bow valve shifts the position of the wave generated at the bow and interferes 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.

With the effect of the bow valve in mind, the present inventors have significantly reduced the water surface compared to the bow valve against local wave formation and local turbulence caused by the rise in the bow water surface. By installing a full load water line valve with a scale of about ascending scale in the vicinity of the full load water line, especially above the full load water line, it is possible to effectively cancel the waves generated by the hull of the submerged part due to the rise in the water surface during navigation. We thought that this could be done, and conducted experiments and numerical calculations to arrive at the present invention.
JP 2003-327193 A JP-A-8-142974

  The present invention has been made in order to solve the above-mentioned problems, and the object of the present invention is to create a hull form that takes into account the rise in the water surface near the stagnation point at the bow, thereby creating wave resistance and waves during navigating in flat water. An object of the present invention is to provide a ship capable of reducing both an increase in resistance in waves during middle navigation.

  In order to achieve the above object, the ship of the present invention has a full-length waterline valve that is at least partially submerged when navigating in plain water in a full-fledged draft state at the bow portion of the ship. It is provided and configured so that its position is above the full waterline of the ship.

  This configuration can reduce the wave resistance generated by the valve effect in the portion where the water surface of the bow rises in the flat water navigation state, and the wave incident on the bow in the ocean navigation state. Can be deflected laterally without being reflected forward by the rectifying effect of the bulb, so that an increase in resistance due to incident waves can be reduced.

  Further, in the above-described ship, if the lower end position in the vertical direction of the full load water line valve is provided above the full load water line of the ship, the full load water line valve is provided above the full load water line. The shape of the waterline surface remains unchanged, so the ship's representative length (waterline length (LWL), vertical length ( Lpp), total length (Lo), etc.) are not affected. Therefore, the basic design and the structural design performed based on these lengths are not greatly affected, and it is possible to avoid re-design calculations and large design changes.

  With regard to the position and size of this full load waterline valve, the wave height encountered during navigation can be statistically predicted by the navigation area, so the design wave height and flat water set based on this prediction It can be determined in consideration of the amount of rise in the water level near the stagnation point of the bow (still water).

  Further, the predetermined set height is set to 0.5 times the water head calculated by (0.5 × Vs × Vs) / g, where Vs is the navigation speed of the ship and g is the acceleration of gravity. The center position in the vertical direction of the full load water line valve is set between the full load water line and a position that is higher than the full load water line by a predetermined set height, and the maximum valve width of the full load water line valve is set to Vs. When the gravitational acceleration is g, it is formed below the head calculated by (0.5 × Vs × Vs) / g, for example, 0.5 to 1 times the head, or the tip of the full load water line valve Position the bow perpendicular F. P. And a foremost portion of the bow above the full waterline.

  If the center position in the vertical direction of this full load waterline valve is made too low, the effect of reducing wave-making resistance against the rise in the water surface will be reduced, and the amount of wave shot from above on the full load waterline valve will increase. It becomes easy to receive damage. On the other hand, if the height is too high, many of the incident waves collide with the lower part of the full load water line valve, and the impact force by the waves becomes large, which is not preferable.

  Also, regarding the maximum valve width, if the maximum valve width is made too small, the valve effect will decrease, making it impossible to balance the cost for installing the full-length waterline valve, and conversely, increasing the maximum valve width. After that, it becomes easy to be damaged by the wave driving, and the vertical force by the wave acting on the valve becomes large, and the influence of the full load waterline valve on the pitching (pitch) and heaving (vertical swing) of the hull movement is affected. It becomes too large and is not preferable.

  Therefore, by setting the design standard of the full load water line valve to the above position and size, the design becomes easy, and in view of the balance between the cost for providing the full load water line valve and the magnitude of the resistance reduction effect, This is a preferred range. The position, size, and shape of the full load water line valve are specifically adapted to each sea area of the actual ship, the original hull form, and the like based on the results of the aquarium test and numerical calculation. Normally, a single full-length waterline valve is provided for a single hull, but a plurality of full-length waterline valves may be provided for a single hull. For example, a pair of small valves is provided on the left and right.

  Furthermore, in the above-described ship, if a wavy member having a horizontal cross section is provided between the upper part of the full load water line valve and the bow flare, this wavy member can also deflect the incident wave in the lateral direction. Even when a large wave that is higher than the upper end of the full load water line valve is incident, the wave cutting member can divide the wave into left and right to reduce the increase in resistance in the waves. In addition, the wave cutting member can avoid the wave driving to the upper part of the full load water line valve and prevent the full water line valve from being damaged by the wave driving.

  The lower part of this corrugated member may be connected to the upper part of the full load water line valve, or may be provided separately. In addition, it will become advantageous in terms of strength if it is formed by connecting the wave cutting member and the upper part of the full load water line valve.

  In addition, various shapes can be considered for the shape of the corrugated member, but the tip position of the corrugated member is a straight line connecting the tip position of the full load water line valve and the foremost portion of the bow above the full load water line, or Providing behind the straight line is more preferable because the shape seen from the side of the bow becomes simple and the wave of incident waves flows smoothly.

  In addition, if the maximum width of the corrugated member is less than the maximum valve width, when the wave rises, even if it rises around the side of the full load water line valve, it hits the lower surface of the corrugated member, It is more preferable because it does not enter the inside.

  Further, the above-mentioned ship is a ship having a hull square coefficient Cb of 0.80 to 0.90 and a voyage speed Vs of 0.12 to 0.20 in terms of Froude number Fn, or the length between perpendiculars (Lpp). In particular, a large effect can be obtained in the case of a large enlargement ship such as 150 m to 350 m.

  This square coefficient Cb is a dimensionless which becomes Cb = V / (Lpp × B × d), where V is the drainage volume of the ship, Lpp is the length between the normals of the ship, B is the mold width, and d is the mold draft. Is the value of

This Froude number Fn is a dimensionless display relating to the ship speed Vs, and is a dimensionless value that satisfies Fn = Vs / (g × Lpp) ^1/2 when the distance between the normals of the ship is Lpp and the gravitational acceleration is g. It is. Note that the nautical speed Vs is sometimes referred to as a planned speed or the like, and therefore the nautical speed is assumed to include the planned speed in this case as well. In addition, the present invention has a large effect on a low-speed enlargement ship, but can also be applied to a catamaran or the like.

  According to the ship of the present invention, in consideration of the wave-making resistance due to the rise of the water surface at the bow when navigating in the full-draft draft state, the rectification effect and the wave effect on the rise of the water surface and the incident wave, By using the hull form provided with, it is possible to reduce a decrease in wave resistance when navigating in flat water in a full draft and an increase in resistance during wave navigation.

  In addition, by installing a waving member above the full-load waterline valve, even in the case of a large wave, it is possible to divide the wave into left and right to reduce the increase in resistance in the waves, and to drive the wave into the full-load waterline valve. Can be relaxed.

Hereinafter, embodiments of a ship according to the present invention will be described with reference to the drawings.
As shown in FIGS. 1 to 4, the ship 1 according to the first embodiment of the present invention is at least when navigating in plain water at a voyage speed Vs in a full draft state above the full draft line df of the ship 1. A full-length draft valve 10 that is partially submerged is provided at the bow.

  As shown in FIG. 2, the center position Zbc in the vertical direction of the full load water line valve 10 is provided between the full load water line df and a position Z1 (= df + h1) higher than the full load water line df by a predetermined set height h1. That is, df ≦ Zbc ≦ Z1. Here, when the predetermined set height h1 is Vs as the navigation speed of the ship and g as the gravitational acceleration, 0. of the water head h2 calculated by h2 = (0.5 × Vs × Vs) / g. Set to 5 times.

  Further, the lower end position Zbb in the vertical direction of the full load water line valve 10 is configured to be above the full load water line df of the ship 1. That is, Zbb> df. With this configuration, the ship's representative length (water line length (LWL), length between vertical lines (Lpp), total length (Lo), which serves as a reference for calculating ship outline, structural strength, etc. Etc.) is not affected, and therefore has little influence on the basic design and structural design performed based on these representative lengths.

  Further, if the maximum valve width Bb of the full load water line valve 10 is too small, the valve effect is reduced, and if it is too large, damage due to wave driving and the influence on the hull motion due to waves acting on the valve become too large. Preferably, when the speed of navigation of the ship 1 is Vs and the acceleration of gravity is g, it is formed below the head h2. More preferably, it is 0.5 times or more of the water head h2. That is, 0.5 × h2 ≦ Bb ≦ h2.

  Furthermore, the tip position Xb of this full-length waterline valve 10 is the vertical line F.V. P. And the foremost part Xa of the bow. In other words, Lb ≦ La in FIG. This bow most advanced portion Xa is the most distal portion in the portion above the full load water line df.

  Regarding the shape of the full load water line valve 10, the cross-sectional shape is usually formed in a circular shape or an elliptical shape close to a circular shape, but may be in other shapes. Further, the side cross-sectional shape is usually formed in a shape that becomes a part of an ellipse, but may be other shapes. It is preferable in terms of fluid dynamics that the shape of the full load waterline valve 10 is formed in a streamline shape with a smooth curve, but in terms of workability, it is preferably formed in a polygonal shape including a plane. For each case, determine each balance.

  This full load water line valve 10 can reduce the wave resistance generated at the portion where the water surface of the bow rises in the flat water sailing state by the valve effect, and in the wave sailing state, it enters the bow. The incoming wave can be deflected laterally by the rectifying effect of the full load water line valve 10, and the increase in resistance due to the incident wave can be reduced.

  Next, a second embodiment will be described. As shown in FIGS. 5-8, the ship 1A of 2nd Embodiment which concerns on this invention sets the full load water line valve | bulb 10 above the full load water line df of the ship 1A similarly to 1st Embodiment. Although it is provided at the bow portion, it is further configured by providing a corrugated member 20 having a wedge-shaped horizontal section between the upper part of the full-load waterline valve 10 and the bow flare 30.

  The rippling member 20 is configured so that the tip position Xw (z) (Zbc ≦ z ≦ Z3) of the rippling member 20 on the full load water line valve 10 and at a height z lower than the position Z3 of the upper deck is expressed as a full load water line. Provided on the straight line L connecting the tip position Xb of the valve 10 and the foremost portion Xa of the bow above the full load water line df or behind the straight line L (provided on the straight line L in FIG. 6), and The maximum width Bwmax of the corrugated member 20 is formed to be equal to or less than the maximum valve width Bb. That is, Bw (z) ≦ Bwmax ≦ Bb.

  As shown in FIG. 8, the wavy member 20 is generally formed in a triangular wedge shape with a horizontal cross-sectional shape, but may be formed in a sharp tip shape having a convex curve or a concave curve. . Accordingly, the side surface portion of the corrugated member 20 is usually formed in a flat plate shape with good workability, but may be a concave curved surface or a convex curved surface. A watertight structure may be provided between the wave cutting member 20 and the bow flare 30, or a structure in which water enters between the bow flare 30 simply by maintaining a wedge-shaped surface. Further, depending on the wavelength and wave height of the target incident wave, a water passage hole may be provided in the corrugated member 20 in order to reduce the reflection of the incident wave forward.

  The wave cutting member 20 provided above the full load water line valve 10 can reduce the increase in resistance in waves by dividing the wave into left and right even for large waves, and the wave to the full load water line valve 10 can be reduced. The driving can be eased.

  Therefore, according to the ships 1 and 1A having the above-described configuration, due to the valve effect of the full load water line valve 10 and the wave cutting effect of the wave cutting member 20, the wave-making resistance is reduced when navigating in the flat water in the full water draft and the wave is traveling in the waves. The increase in resistance in waves can be reduced, and excellent propulsion performance can be exhibited in the navigation state with full draft.

  This effect is obtained when the rectangular coefficient Cb is 0.80 to 0.90 and the voyage speed Vs is 0.12 to 0.20 in terms of Froude number Fn or the length between the perpendiculars (Lpp) is 150 m to 350 m. It is especially large in the case of large low-speed enlargement ships such as.

  As an example, in a bulk carrier hull form having a hull square coefficient (Cb) of 0.85, a captain formed by providing a full-length waterline valve 10 and a corrugated member 20 as shown by a solid line A in FIGS. A model ship with (Lpp) of 2.7 m was prepared.

  In addition, as a conventional example, the same bulk carrier hull form is the same as the example except for the bow part, but a conventional bow part shape in which the full waterline valve 10 and the corrugated member 20 are not provided in the bow part is adopted. A model ship with the same captain (Lpp) was prepared.

FIG. 9 shows the results of a wave resistance test conducted on these model ships in a water tank. In FIG. 9, the horizontal axis represents λ (wavelength) / L (captain) of a regular wave, and the vertical axis represents the increase in resistance Rau in waves in the regular wave by ρ × g × Hw ² × (B ² / L ) Shows a resistance increase coefficient Caw in waves, which is a dimensionless value. Here, the resistance increase amount Raw in the wave is a value obtained by subtracting the resistance in the water from the resistance in the wave, ρ is the density of water, g is the acceleration of gravity, Hw is the significant wave height (both amplitudes), B indicates the width of the ship, and L indicates the length between the perpendiculars.

  FIG. 9 shows that the wave resistance increase coefficient Caw of the example (solid line A) is smaller than that of the conventional example (dotted line B).

It is a fragmentary perspective view which shows the shape of the upper part from the full load water line of the bow part of the ship of 1st Embodiment which concerns on this invention. It is a partial side view which shows the shape of the bow part of the ship of FIG. It is a partial front view which shows the shape of the bow part of the ship of FIG. FIG. 3 is a horizontal sectional view (waterline view) of a height Zbc showing the shape of the full-load draft valve of the ship of FIG. 1. It is a fragmentary perspective view which shows the shape of the upper part from the full load water line of the bow part of the ship of 2nd Embodiment which concerns on this invention. It is a partial side view which shows the shape of the bow part of the ship of FIG. It is a partial front view which shows the shape of the bow part of the ship of FIG. FIG. 6 is a horizontal sectional view (waterline view) of height z showing the shape of the full-load draft valve and the shape of the bottom portion of the corrugated member of the ship of FIG. 5. It is a figure which shows the comparison of the resistance test result in the wave of an Example and a prior art example. It is a figure for demonstrating the water surface rise in a bow part.

Explanation of symbols

1 Ship 1A Ship (Example)
1X Ship (conventional example)
10 Full load water line valve 20 Wave cutting member 30 Bow flare Bb Maximum width of full load water line valve Bw (z) Width of wave cutting member Bwmax Maximum width of wave cutting member L. Hull Chuo Line (Center Line)
df Full draft (structural draft)
F. P. Bow vertical line Fn Froude number g Gravity acceleration h1 Predetermined set height h2 Head at the stagnation point hs Head far away from the bow L Connects the tip of the full-load draft valve and the most advanced portion of the bow above the full-scale draft Straight line O Stagnation point
Xa The tip of the bow above the full load water line Xb The tip of the full load water line valve Xw (z) The tip of the wave cutting member z Height Z1 The position of the predetermined set height Z2 The water level rising position of the stagnation point (flat water)
Zbc Center position in the vertical direction of the full load waterline valve Zbu Bottom position in the vertical direction of the full load waterline valve Vs Navigational speed Vo Flow rate at the stagnation point

Claims (8)

  At the bow part of the ship, a full load water line valve that is at least partially submerged when navigating in flat water in the full water draft state is provided so that the center position in the vertical direction of the full load water line valve is above the full load water line of the ship. A ship characterized by that.   The ship according to claim 1, wherein a lower end position in a vertical direction of the full load water line valve is provided to be higher than a full load water line of the ship.   The predetermined height is set to 0.5 times the head calculated by (0.5 x Vs x Vs) / g, where Vs is the navigational speed of the ship and g is the acceleration of gravity. The ship according to claim 1 or 2, wherein a central position in the vertical direction of the waterline valve is provided between a full load waterline and a position higher than the full load waterline by the predetermined set height.   The maximum width of the full load water line valve is formed below the water head calculated by (0.5 × Vs × Vs) / g, where Vs is the navigation speed of the ship and g is the acceleration of gravity. The ship according to any one of claims 1 to 3.   The tip position of the full load water line valve is defined by the bow perpendicular F.R. P. The ship according to any one of claims 1 to 4, characterized in that the ship is provided between the foremost portion of the bow above the full load water line.   The ship according to any one of claims 1 to 5, wherein a waving member having a wedge-shaped horizontal cross section is provided between an upper portion of the full load water line valve and a bow flare.   The tip position of the corrugated member is provided on the straight line connecting the tip position of the full load water line valve and the foremost portion of the bow above the full load water line, or behind the straight line. The marine vessel according to any one of claims 1 to 6, wherein a large portion is formed below the maximum valve width. 8. The ship according to claim 1, wherein the ship has a square coefficient of 0.80 to 0.90 and a navigation speed of 0.12 to 0.20 in terms of fluid number. Ship.

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