JP4721501B2 - Ship - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ship excellent in maneuvering performance, particularly in course stability.
[0002]
[Prior art]
Ship maneuvering performance is composed of three elements: turning performance, followability to steering, and course stability. Of these, course stability refers to the ability of a ship's turning motion caused by a disturbance to quickly decay and settle straight without moving the rudder. This course stability is associated with this, and it is easy for a ship excellent in both to keep the course while sailing.
[0003]
By the way, the main item and the hull form of a hull are generally determined by the weight of cargo, propulsion performance, restoration performance, and port limiting factors. The course stability may not always be sufficient. However, even if an attempt is made to improve the course stability and to change the main eyes and the hull form, it is difficult to change from other design conditions, and such a tendency becomes more prominent as the ship becomes an enlarged ship.
[0004]
A conventional technique for improving the course stability is disclosed in Japanese Patent Laid-Open No. 8-216992. As shown in the perspective view of FIG. 6, this course stabilization device for a ship is a course stabilization device in which a flat plate 22 is horizontally extended and attached to a skeg 21, and the outer edge of the flat plate 22 has a shape matching the ship side line. The rear end coincides with the rear end of the skeg 21 and the mounting height position of the flat plate 22 is in the range from the bottom of the ship to the position of the propeller shaft 23, and the lateral overhang width of the flat plate 22 is at the center of the hull. It is comprised in the range of 1/60-1/5 of a half width.
Thereby, when the hull turns, the water flow flowing from the stern side to the bottom of the hull is blocked by the flat plate 22 to generate a lateral force on the hull, and this lateral force acts in a direction to attenuate the turning force. Is to improve.
[0005]
Japanese Patent Laid-Open No. 11-255178 discloses a ship in which course stability is improved by attaching a rectifying fin on the ship side. FIG. 7A is a schematic side view of the stern part of FIG. 7A, FIG. 7B is a view taken along the line AA in FIG. 7B, and FIG. 7C is a view taken along the line BB in FIG. Explaining with the CC arrow view of FIG. 7 (d), the draft line D. L. The rectifying fins 34 are attached to the submerged position below the boat side parallel portion 32 so as to extend from the rear end 32a of the ship side parallel portion 32 toward the stern 33, and the rear end 32a of the ship side parallel portion 32 near the bottom 35 of the ship side 31 A rectifying fin 36 is attached at a position intermediate to the stern 33 so as to rise gently toward the stern 33. Then, the downward flow 37 from the ship side parallel portion 32 is rectified by the rectifying fins 34 and guided to the stern 33 side, and the upward flow 38 from the bottom 35 is rectified by the rectifying fins 36 and guided to the stern 33 side.
[0006]
In this configuration, when the downward flow 37 from the ship side parallel part 32 and the upward flow 38 from the ship bottom 35 collide in the vicinity of the rear end 32a of the ship side parallel part 32 during the turning motion, The stern 33 is pulled to the outside due to a negative pressure at the part, so the downward flow 37 is suppressed by the rectifying fins 34 and the upward flow 38 from the bottom 35 is pressed by the rectifying fins 36. This is to suppress the collision between the downward flow 37 and the upward flow 38.
[0007]
[Problems to be solved by the invention]
However, the above-described technology for improving the course stability of the conventional ship has the following problems. FIG. 8 is a diagram schematically showing the location and size of the hydrodynamic force acting on the stern 42 when the ship 41 is tilting or turning. The ship course stabilizing device disclosed in Japanese Patent Laid-Open No. 8-216992 is intended to increase the resistance 1 against turning by increasing the fluid force 1 in FIG. Since the projecting area extends to the vicinity of the propeller position, the ascending flow from the ship bottom is disturbed by the flat plate being prevented from ascending by the flat plate, and as a result, the propulsion performance deteriorates.
[0008]
Moreover, the ship disclosed by Unexamined-Japanese-Patent No. 11-255178 reduces the fluid force 2 in a figure, and, as a result, increases the resistance force with respect to turning. Although there is little adverse effect on the propulsion performance, the fluid force 2 has a center of force on the center of the hull compared to the fluid force 1, so the turning moment is small and the effect on the course stability increases the fluid force 1 Small compared to
[0009]
The present invention has been made to solve the above-described problems of the prior art, and an object thereof is to provide a ship capable of improving course stability without adversely affecting propulsion performance. .
[0010]
[Means for Solving the Problems]
In the ship according to the present invention, the fin having a length of 2.5 to 10% of the length of the ship is within the range of 30% or less of the length of the ship from the position just before the propeller of the hull to the bow direction. The height of 0-5%, the stern side mounting position is from the bottom of the ship to 15% of the draft, and the mounting line connecting the fin's bow side and stern side's mounting position rises gently toward the stern. is attached so that the line, tip of fins, the ship's bottom and mounted overhanging substantially the full fin so that the same becomes the height obliquely downward from the hull, and the hull of the state in which no fins attached to pivot It is the position that exceeds the dead water area formed on the ship side . Further, a plurality of the fins are attached to both ship sides.
[0011]
In the ship according to the present invention, when the hull turns, the water flow that flows from the stern stern side to the bottom of the ship and flows again to the opposite ship side is largely separated by the vortex-forming phenomenon caused by the fins, so that The area is increased compared to the case without fins, and as a result, the lateral force acting on the latter half of the hull is increased. Since this lateral force acts in a direction to reduce the turning force, the course stability is improved.
[0012]
The reason why the fins are provided in the range of 30% or less of the captain from the front of the propeller to the bow direction is that the lateral force generated by the fins effectively acts as a resistance moment against turning, and the lateral force is applied to the rear part of the hull. Because the moment lever increases as it occurs near the stern, and the flow velocity of the water flow caused by the turning angle of the hull increases, the vortex created by the fins also increases, and the lateral force itself increases. By becoming.
[0013]
Moreover, since the fins are attached so that the ship side attachment line of the fins is a line that gently rises toward the stern, the fins can be made to follow the streamline that flows on the ship side when going straight. As a result, the flow field unique to the hull is not disturbed, so that an increase in resistance during straight travel does not occur. In addition, since the upward flow from the bottom of the ship is not disturbed and the flow field flowing into the propeller is not disturbed, there is no adverse effect on the propulsion performance.
[0014]
The height of the fin's bow attachment position is 0-5% of the draft from the bottom of the ship, and the height of the stern attachment position is 15% of the draft from the ship's bottom. This is to bring the streamline closer to the streamline that flows on the ship side, and the streamline differs depending on the hull form.Therefore, adjust the height of the fin's bow and stern side mounting positions within this range to bring the fin attachment line closer to the streamline. Just do it.
[0015]
When the fins are attached to the ship side under the above-described conditions, the lateral force generated becomes smaller if the fin length is 2.5% or less of the ship length, and the effect of improving the course stability cannot be exhibited.
Also, if the fin length is 10% or more of the length of the captain, the degree of rise toward the stern of the fin attachment line will be too gentle, and the fin will leave the streamline and hinder the flow entering the propeller when going straight. Or cause an increase in resistance, adversely affecting propulsion performance. Therefore, the length of the fin is in the range of 2.5 to 10% of the ship length.
[0016]
When the stern causes a lateral movement in the port direction due to the turning motion, a lateral flow from the port side to the starboard side is generated. As shown in FIG. 9A, the flow descends from the port 51a side of the hull 51, passes through the bottom 51b and tries to rise on the starboard 51c side, but along the outer peripheral surface of the hull 51 on the way. The flow can no longer flow, the flow is separated from the hull 51, and a dead water region 52 is formed on the starboard 51c side.
The effect of improving the course stability by the fin is brought about by obtaining a large lateral force by enlarging the peeling area on the starboard side due to the vortex formation phenomenon at the tip of the fin. The effect is greater when it is outside the dead water area 52 to be built. For this reason, as shown in FIG. 9B, the position of the tip 53a of the fin 53 is not limited to the dead water region 52, but is extended to a position having substantially the same depth as the ship bottom 51c.
[0017]
As described above, since the fins used in the ship according to the present invention do not adversely affect the propulsion performance, attaching a plurality of fins causes more vortices that improve the course stability than in the case of a single fin. Since it can be created, it is possible to realize a ship with better course stability.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
1A and 1B are explanatory views showing a first embodiment of a ship of the present invention, in which FIG. 1A is a perspective view of a stern part of the ship, and FIG. 1B is an AA arrow view of FIG.
In this ship, one fin 4 is attached to each ship side 3 near the stern 2 of the hull 1. The fins 4 are attached within a range of 30% or less of the length of the hull 1 from the front of the propeller 5 toward the bow direction, and the length L is 2.5 to 10% of the length of the hull 1.
In addition, the bow side attachment position of the fin 4 is 0 to 5% of the draft from the ship bottom 6, and the stern side attachment position of the fin 4 is 15% of the draft from the ship bottom 6, And the attachment line 4a of the fin 4 is attached so as to be a line that gently rises toward the stern 2, and can follow the streamline flowing on the shore side when going straight, preventing disturbance of the upward flow from the bottom 6 It has a structure to do.
In addition, the wing tips 4b of the fins 4 project the fins 4 obliquely downward so that they are at the same depth as the bottom 6 of the ship. Therefore, the planar shape of the fin 4 is a triangular shape or a trapezoidal shape in which the projecting width increases from the bow side to the stern side.
[0019]
FIG. 2 is a perspective view showing a second embodiment of the ship of the present invention. In the case of this ship, a plurality of fins 14a to 14c are attached to the ship side 13 of the hull 11, but also in this ship, the mounting conditions of the individual fins are the same as those of the ship of the first embodiment. is there. In the case of this ship, since there are many fins, the improvement effect of course stability increases further than the ship of 1st embodiment.
[0020]
【Example】
A model ship with a size of 1/70 that of an actual tanker and a ship with one fin attached on both sides, similar to the ship of the first embodiment, and performing model tests in the hull test tank went. This model test is a free-running model test, in which a model ship made completely free is rotated by rotating the attached propeller with a remote controller, and the movement state of the model ship at that time is measured.
[0021]
This test is a test for grasping the maneuvering performance usually called the Z test, and the course stability performance of the ship is evaluated.
[0022]
FIG. 3 is a diagram showing the change over time in the rudder angle and the azimuth angle of the hull in the Z test.
In the figure, the broken line indicates the change over time in the rudder angle, and the solid line indicates the change over time in the azimuth angle of the hull.
In the Z test, the steering angle is first set to 10 degrees, and when the azimuth angle of the hull reaches 10 degrees, the operation is repeated so that the rudder is set to 10 degrees on the side opposite to the previous time so that the steering angle is restored. It is a going test. The direction of the hull does not attempt to return to the original at the same time as turning the rudder angle, but rather to return to the original after reaching a maximum azimuth angle that is somewhat larger than the rudder angle.
The absolute value of the value obtained by subtracting the azimuth angle when turning the rudder from the maximum azimuth angle of the ship is called the overshoot angle, which is the overshoot at the first turn back. The toe angle is referred to as the first overshoot angle, and the overshoot angle at the second turning back is referred to as the second overshoot angle.
Although FIG. 3 shows a case where the steering angle is first taken at +10 degrees, this is called an S10 ° Z test, and conversely, a case where the steering angle is taken first at −10 degrees is called a P10 ° Z test.
It is said that the smaller the first overshoot angle and the second overshoot angle, the better the tracking of the hull to the rudder and the better the course stability.
[0023]
FIG. 4 shows the overshoot angle of the hull with fins measured in the S10 ° Z test in comparison with the overshoot angle of a normal hull without fins. In the figure, ◯ indicates the first overshoot angle, and ● indicates the second overshoot angle. In the case of a hull with fins, the first overshoot angle is 1.2 °, the second overshoot angle is 5.2 °, and the overshoot angle is more than the normal hull shape. It can be seen that the effect of improving the course stability appears.
[0024]
In general, in model tests, frictional resistance is greater than in actual ship tests due to the scale ratio, and it is necessary to increase the propeller rotation speed in order to achieve a ship speed that satisfies the fluid similarity law. .
However, when the number of rotations of the propeller is increased, the speed of the wake of the propeller increases, the flow velocity hitting the rudder increases, a rudder force larger than that of the actual ship is generated, and the steering is improved. For this reason, the overshoot angle of the model test is smaller than that of the actual ship.
Therefore, a simulation calculation equivalent to an actual ship was performed, and the overshoot angle in the actual ship was estimated from the relationship between the model test result and the simulation result corresponding to the model test. The result is shown in FIG.
In this case, in the case of a hull type with fins, the first overshoot angle is 2.9 °, the second overshoot angle is 12.0 °, and the overshoot is larger than the normal type. -The angle is small, and it can be seen that the effect of improving the course stability on an actual ship is even greater.
[0025]
In order to understand the impact on propulsion performance, a propulsion performance test was performed using the same model ship, and the main engine horsepower required to produce the planned speed was estimated. The main engine horsepower required to produce the planned speed is slightly more than 1% lower than that of the normal hull in the case of a hull with fins, so it was confirmed that the effect of the fins on propulsion performance is small.
[0026]
【The invention's effect】
According to the present invention, it is possible to obtain a ship having excellent course stability without deteriorating the propulsion performance when traveling straight.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a first embodiment of a ship of the present invention, where (a) is a perspective view of a stern portion of the ship, and (b) is a view taken along the line AA of (a). .
FIG. 2 is a perspective view showing a second embodiment of the ship of the present invention.
FIG. 3 is a diagram showing changes over time in a steering angle and an azimuth angle in a Z test.
FIG. 4 is a diagram showing an overshoot angle of a hull with a fin measured in an S10 ° Z test in comparison with an overshoot angle of a normal hull without fins.
5 is a diagram showing an overshoot angle in an actual ship estimated based on an overshoot angle of the model ship shown in FIG. 4. FIG.
FIG. 6 is a perspective view of a conventional marine course stabilizer.
7A and 7B are explanatory views of a ship provided with a conventional course stability improving fin, wherein FIG. 7A is a schematic side view of the stern part, FIG. 7B is a view taken along the line AA in FIG. ) Is a BB arrow view of (a), and (d) is a CC arrow view of (b).
FIG. 8 is a diagram schematically showing the location and magnitude of a fluid force that acts on the stern 2 when the ship is skewing or turning.
FIG. 9 is an explanatory diagram of a lateral flow from the port side to the starboard side that occurs when the stern makes a lateral movement in the port direction, and (a) is a diagram when (b) is not provided with fins on the ship side; ) The case where fins are provided on the ship side is shown.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Hull 2 Stern 3 Ship side 4 Fin 4a Fin attachment line 4b Fin wing tip 5 Propeller 6 Ship bottom 11 Hull 13 Ship side 14a-14c Fin

Claims (2)

The fin of 2.5 to 10% of the length of the captain is within 30% of the length of the ship from the position just before the propeller of the hull toward the bow, and the installation position on the bow is 0 to 5% of the draft from the ship's bottom. In addition, the stern side mounting position is at a height of 15% from the ship bottom to the draft, and the mounting line connecting the fin's bow side and stern side mounting position is a line that gently rises toward the stern. The dead water area formed on the ship side when the hull is turned with the fins extending obliquely downward from the ship side so that the wing tips of the fins are at the same height as the ship bottom. A ship characterized by being in a position exceeding. The ship according to claim 1, wherein a plurality of the fins are attached to both ship sides.

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