JP2005059715A - Resistance reduction device for vessel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable resistance in a low-speed range to be reduced. <P>SOLUTION: A flat plate-like fin 6, extending substantially in parallel with a ship bottom surface 5 in a ship width direction over a predetermined distance against the ship bottom surface 5, is arranged below a rear end of the ship bottom surface 5 and then fixed to the ship bottom surface 5 via a support stay 8. The fin 6 is fixed at a predetermined pitching angle θ with respect to a water flow along the ship bottom surface 5, in such a way that a clearance 7 formed between the fin 6 and the ship bottom surface 5 expands wide from the head to the stem. The water flow, generated relatively along the ship bottom surface 5 by forwarding the hull 1, is accelerated by the principle of wing at the upper surface of the fin 6 having the pitching angle θ with respect to the water flow along the ship bottom surface 5, when the water flow is flowed at the clearance 7 between the fin 6 and the ship bottom surface 5 and then water-creasing performance at the lower end of the transom-type stem 3 is improved by this accelerated water flow 9. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a ship resistance reducing device for reducing resistance such as wave resistance during low speed navigation of a ship, particularly a ship having a transom type stern.

A transom type stern, which has a shape with a corner by cutting the rear end of the hull in a substantially vertical direction, is often used as a stern shape for car ferries and other ships. A ship using such a transom stern usually has a corner formed at the rear end of the bottom of the transom stern, and the corner at the lower rear end of the transom stern is when the ship is stopped. Submerged.

For this reason, when the ship with the transom stern navigates at a high speed,
As shown in FIG. 4 (a), the hull 1 drains water, so that the water surface 2 has the same height as the lower rear end of the transom type stern 3, so that the resistance at the stern 3 is reduced. In the case where the hull 1 does not drain water, such as when the navigation speed is low, the water surface 2 comes above the lower rear end of the transom type stern 3 as shown in FIG. Dead water area 4 behind
This causes a problem of generating resistance. In addition, 5 shows a ship bottom.

By the way, as a device for reducing the hull resistance of a ship, a water flow passing through the stern part of the hull as the hull advances is attached by attaching a wing-shaped rectifying fin along the surface of the hull of the stern part to the stern part with a support frame. By suppressing the separation of water flow from the surface of the hull,
Conventionally proposed is one that suppresses the generation of vortices to reduce the hull resistance (see, for example, Patent Document 1).

Japanese Utility Model Publication No. 5-3092

However, the one described in Patent Document 1 is for preventing the water flow passing through the surface of the hull when the hull moves forward from being separated from the surface of the hull. In the case of low speed navigation, no consideration is given to the formation of a dead water area behind the transom type stern. Therefore, what was described in the said patent document 1 cannot solve the problem that resistance generate | occur | produces in connection with the dead water area behind the stern at the time of low speed navigation of the ship which has a transom type stern.

Therefore, the present invention is intended to provide a resistance reduction device for a ship that can reduce the resistance of a ship having a transom type stern during low-speed navigation.

In order to solve the above-mentioned problems, the present invention is a flat plate-like shape formed on the lower side of the stern rear end of the ship so as to extend substantially parallel to the ship bottom surface in the ship width direction with a required distance from the ship bottom surface. The fins are arranged, and the fins are attached at a required angle of attack with respect to the profile line on the bottom of the ship so that a gap formed between the fin and the bottom of the ship is widened from the bow side toward the stern side.

Further, the fin has a configuration in which the front end edge portion has a smooth circular arc shape and the cross-sectional shape is formed by chamfering the rear upper surface side.

Further, the angle of attack formed with respect to the profile line on the bottom surface of the fin is set to about 1 to 20 degrees.

As described above, according to the ship resistance reducing apparatus of the present invention, the following excellent effects are exhibited.
(1) A plate-like fin formed so as to extend substantially parallel to the bottom of the ship in the width direction of the ship at a distance from the bottom of the ship is arranged below the rear end of the stern of the ship, and the fin is Because the gap formed between the bottom of the ship and the bottom of the ship is widened from the bow side toward the stern side, it is installed at the required angle of attack with respect to the profile line on the bottom of the ship. When a relatively flowing water flow is passed through the gap between the bottom of the ship and the fins, the water flow is generated according to the wing principle on the upper surface of the fin having the required angle of attack with respect to the water flow along the bottom of the ship. It can be accelerated.
By passing this accelerated water flow through the bottom of the stern, the draining ability of the bottom of the stern can be improved, and therefore the draining ability of the hull can be improved even when the navigation speed is in a low speed range. Therefore, it is possible to reduce the hull resistance by suppressing the generation of resistance such as wave resistance.
(2) Since the fin has a smooth arc shape at the front end edge and a cross-sectional shape formed by chamfering the rear upper surface side, the fin can be streamlined.
An increase in the resistance of the hull accompanying the attachment of the fins can be suppressed.
(3) By making the angle of attack made with respect to the profile line on the bottom of the fins about 1 to 20 degrees, the water flow passing between the fins and the bottom of the ship can be efficiently accelerated. it can.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 (a) (b) and FIG. 2 show an embodiment of the ship resistance reducing device of the present invention. In a ship having a transom stern similar to that shown in FIGS. 4 (b) (b). A flat plate-like fin 6 extending in the width direction of the ship so as to follow the surface shape of the ship bottom and extending substantially in parallel with the ship bottom surface 5 at a position below the rear end of the ship bottom 5 of the transom stern 3. A profile of the bottom surface 5 is arranged such that a necessary gap 7 is disposed therebetween and the gap 7 is wider from the bow side (front end side of the fin 6) toward the stern side (rear end side of the fin 6). The mounting angle (attack angle) θ of the fin 6 with respect to the line in the front-rear direction is about 1 to 20 degrees, preferably about 5 degrees, and the fin 6 is supported on the bottom surface 5 in the vertical direction. Suspended and supported through the stay 8.

More specifically, as shown in the enlarged cross-sectional view of FIG. 2, the fin 6 has a smooth arcuate front end edge of the cross-sectional shape and the upper surface side of the rear portion at a required angle, for example, about 30 degrees. By chamfering, the thickness is gradually reduced toward the rear edge, so that the cross-sectional shape of the fin 6 becomes a streamline shape as a whole. The upper surface of the fin 6 and the rear chamfered surface are processed so as to be continuous with a smooth radius. In FIG. 2, the thickness dimension is shown enlarged for convenience of showing the cross-sectional shape of the fin 6. Therefore, the cross-sectional shape shown in FIG. 2 does not reflect the actual cross-sectional shape of the fin 6.

Also, the support stay 8 has a front end edge and a rear end edge of a cross-sectional shape (not shown) having a smooth arc shape so that water can flow smoothly on the left and right sides of the support stay 8. .

Further, the dimension of the fin 6 in the ship width direction is 50 to 100% of the ship width dimension (in FIG. 1 (a), 100% of the ship width dimension is shown). The fin 6
The fin 6 is positioned so that the rear end of the fin 6 is the same as or slightly forward of the end face of the transom stern 3.

In the above description, the angle θ of the fin 6 with respect to the profile line of the bottom surface 5 is set to about 1 to 20 degrees. The acceleration effect of the water flow 9 flowing through the gap 7 between the surface 5 and the fin 6 cannot be expected so much.
If the temperature exceeds the upper limit, the water flow 9 that circulates the gap 7 at the rear end portion of the fin 6 or the rear end portion of the ship bottom surface 5 is likely to peel off from the surface of the fin 6 or the ship bottom surface 5. is there.

  In addition, the same components as those shown in FIGS. 4A and 4B are denoted by the same reference numerals.

According to the ship resistance reducing device of the present invention having the above-described configuration, when the ship is navigated, a water flow that relatively moves backward along the ship bottom surface 5 is generated. For this reason, when the speed at which the hull 1 moves forward reaches a certain level in the low speed range, a water flow that relatively moves rearward along the bottom surface 5 is formed between the bottom surface 5 and the fins 6. When the fin 6 is guided to a gap 7 that is wider from the bow side toward the stern side and is allowed to pass through the gap 7, the fin 6 forms a required mounting angle θ with respect to the water flow along the bottom surface 5. On the top surface, the water flow is accelerated by the wing principle. Accordingly, since the accelerated water flow 9 passes through the lower end side of the transom stern 3, the draining ability at the lower end of the rear end portion of the transom stern 3 is improved.

As described above, the ability of the hull 1 to drain water can be improved, and as shown in FIG. 1 (b), the water surface 2 can be moved to the transom type stern 3 even in the low speed range where the hull 1 has not been drained conventionally. Since it becomes possible to make it the same height as the lower end of the rear end, it is possible to reduce the resistance at the time of low-speed navigation of the ship having the transom stern 3.

Further, since the fin 6 has a streamlined cross-sectional shape, an increase in resistance due to the attachment of the fin 6 can be suppressed as is apparent from the results of the embodiments described later.

The present invention is not limited only to the above embodiment, and the fins 6 are shown as being attached to the ship bottom surface 5 via the support stays 8 at the center and both ends in the ship width direction. As long as the fins 6 can be securely fixed against the resistance of the water to be generated, the arrangement, number, etc. of the support stays 8 may be set freely, and the vertical direction such as the direction perpendicular to the ship bottom surface 5 may be used. It is good also as what extends in directions other than. Of course, the thickness dimension and the front-rear dimension of the fin 6 may be determined according to the size of the target ship, and various changes can be made without departing from the scope of the present invention.

  Hereinafter, the results of experiments conducted by the inventor will be described.

As a model of a ship with a transom type stern, the total length is 6.4m and the draft at the stern is 0.2.
The wave resistance in the case where the fins 6 as shown in FIGS. 1 (a) and 1 (b) and FIG.

2, the front and rear dimension A is 30 mm, the thickness dimension B is 2 mm, the curvature C of the front edge is 1r, and the chamfering angle D of the upper surface is as shown in FIG. It was set to about 30 degrees, and the thickness dimension E of the rear end portion was set to 0.5 mm. Further, the fin 6 was attached to the position 15 mm below the rear end portion of the ship bottom surface 5 along the ship bottom surface 5 over the entire length in the ship width direction. Further, the angle θ of the fin 6 with respect to the profile line of the ship bottom surface 5 was set to 5 degrees.

As a result, when the fins 6 are attached to the hull 1, as shown by a line a in FIG. 3, compared with a case where the fins 6 indicated by a line b are not attached, the predetermined design speed in the low speed region is about 1
The effect of reducing the wave resistance by 0% was confirmed.

In the speed range slower than the design speed, the difference in wave resistance due to the presence or absence of the fin 6 is small, and it can be seen that the increase in resistance due to the attachment of the fin 6 is suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS One Embodiment of the ship's resistance reduction apparatus of this invention is shown, (A) is a schematic rear view, (B) is an XX direction arrow enlarged view of (A). It is a figure which expands and shows the cross-sectional shape of the fin in the apparatus of FIG. It is a figure which shows the experimental result of the wave resistance reduction performed by applying the apparatus of FIG. 1 to a ferry model. The relationship between the navigation state of the ship which has the conventional transom type stern and the water surface is shown, (a) is a schematic side view which respectively shows the case where speed is high, and (b) is the case where speed is slow.

Explanation of symbols

3 Transom type stern (stern)
5 Bottom of ship 6 Fin 7 Clearance θ Angle of attack

Claims (3)

A flat plate-like fin formed so as to extend substantially in parallel with the bottom surface of the ship at a required distance from the bottom surface of the ship is disposed below the stern rear end of the ship, and the fin is disposed on the bottom surface of the ship. A ship resistance reduction device characterized by having a configuration in which a gap formed between the two is widened from the bow side toward the stern side at a required angle of attack with respect to the profile line on the bottom of the ship. The ship resistance reducing device according to claim 1, wherein the fin has a cross-sectional shape formed by chamfering the rear upper surface side while making the front end edge portion a smooth arc shape. The ship resistance reducing device according to claim 1 or 2, wherein an angle of attack formed with respect to a profile line on a bottom surface of the fin is about 1 to 20 degrees.

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