JP2003291883A - Ship - Google Patents

Abstract

(57) [Summary] [Problem] To reduce wind pressure resistance on a ship. SOLUTION: Upper deck 14-1 of hull 11 and both sides 1
6a and 16b, the two corners 17a and 17b, respectively, from the bow 12 to almost the entire length of the stern 13 or the bow 1
2 to the notch steps 17a, 17
b is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cargo ship such as a car carrier and a container ship, a tanker, a passenger ship and the like.

[0002]

2. Description of the Related Art As shown in FIG. 8, the resistance received by a ship 1 while traveling can be divided into underwater resistance and wind pressure resistance. Underwater resistance includes wave-making resistance and frictional resistance, which account for the majority of the total resistance. For this reason, underwater resistance has been studied in the past, and the results of its analysis have been reflected in the current shape of ships. However, wind pressure resistance has been neglected, and the reality is that the shape has not been improved to reduce wind resistance.

[0003]

However, when the ship 1 receives a wind from the front, the ship 1, especially a car carrier, a container ship, a tanker, etc., which has a shape above the water surface that is easily subjected to wind pressure, is directly affected by the wind. Not only the vessel speed decreased, but also the underwater resistance increased due to the attitude change (oblique navigation) of the hull caused by the wind, which sometimes affected the operation performance.

For example, as shown in FIG. 9, when the boat 1 receives a wind 2 obliquely to the left from a course 3, a lateral force is generated from the port side to the starboard direction, and a clockwise yaw moment ( Rotational force) is generated. In order to keep the heading of the boat in the direction of the course 3 against the yaw moment, it is necessary to steer the steering wheel. At this time, the force of water acting on the rudder becomes resistance. Further, since the ship 1 receives a lateral force, it will travel diagonally (in the direction of arrow 4). By performing such an oblique cruise, the underwater resistance acting on the hull increases. At this time, the larger the diagonal angle α, the larger the amount of rudder steering, and the greater the resistance of the hull from water.

The present invention has been made under these circumstances, and its purpose is to provide resistance to wind pressure,
An object of the present invention is to provide a ship that has a hull structure that can reduce lateral force and yaw moment, thereby making it possible to reduce the angle of oblique navigation and the underwater resistance acting on the hull.

[0006]

The invention according to claim 1 is
In order to solve the above problems and achieve the object, there is provided a ship in which notched step portions are provided at both corners that connect the upper deck of the hull and both port side portions over substantially the entire length from the bow to the stern.

The invention according to claim 2 resides in a ship provided with a similar notch step portion over a range from the bow to almost the center of the hull.

In the vessel according to claim 1 or 2, as in the invention according to claim 3, the depth from the upper deck of the notched step portion is 5 to 20% with respect to the freeboard when the ballast is loaded.
It is desirable to set to.

Further, as in the invention according to claim 4, it is more effective to form an inclined surface on the bow portion upward from the upper end of the front edge of the bow toward the upper deck with respect to the horizontal plane.

In the ship according to the fourth aspect, as in the invention according to the fifth aspect, the upward angle of the inclined surface with respect to the horizontal plane may be set to 20 to 60 degrees.

Further, preferably, as in the invention according to claim 6, the upward angle of the inclined surface with respect to the horizontal plane is approximately 38.
Set to every.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

This embodiment is a case in which the notched step portion over the entire length of the present invention is applied to an automobile carrier, and a schematic view of the hull of the automobile carrier is shown in FIG. 1, in which the notched step portion of the hull is provided. FIG. 2 shows a schematic cross-sectional view when the portion is cut in the width direction, and FIG. 3 shows a side view and a top view of the bow portion.

This car carrier is provided with a bow 12 of a hull 11.
A plurality of decks 1 that are almost parallel to the horizontal plane over the stern 13
It has a hierarchical structure partitioned by 4-1, 14-2, 14-3, ..., 14-n. A tower 15 is provided on the bow side of the uppermost deck, so-called upper deck 14-1.

Upper deck 14-1 and port side portions 16a, 16b
At both corners 17a and 17b that connect to and, the notch steps 18a and 18 are provided over substantially the entire length from the bow 12 to the stern 13, respectively.
b is formed. The depth from the upper deck 14-1 of the hull to the keel 19 is D, and the ballast sailing condition, that is, the draft when the ship is sailing with an appropriate amount of ballast without cargo, is f (f = D). -D), the depth g from the upper deck 14-1 of both notch steps 18a and 18b is set to 5 to 20% with respect to the freeboard f. Also,
The width h of both notch steps 18a and 18b is set to be substantially equal to the depth g.

Incidentally, in this embodiment, both notch steps 18a and 18b are formed by the upper deck 14-1 to the second deck 14-.
It is formed by cutting out in a rectangular shape with a width of one automobile as a cargo over the width 2.

The bow 12 of the hull 11 has a front end 1 at the front edge of the bow.
An inclined surface 20 that faces upward from 2a toward the upper deck 14-1
Are formed. The inclined surface 20 is set such that the upward angle with respect to the horizontal plane is 20 to 60 degrees (deg.). Preferably, considering the load capacity and the like, it is almost 38
Good degree (deg.).

The other structure of the hull is the same as that of a conventionally known car carrier, and therefore detailed description thereof will be omitted.

Next, it is shown that the car carrier having the hull structure of the present embodiment is effective in reducing wind pressure resistance, as a result of wind tunnel experiments, and CFD (Computational Fluid Dynamic).
s) Explain from the results of numerical analysis using the solver.

By the way, in the wind tunnel experiment, an air passage having an opening in the upstream and the downstream (height 110 m, width 480 m, length 600)
m) is built, and a car carrier to be tested is installed in the interior so that the bow faces the upstream side of the air passage, and wind with different wind direction (relative wind direction = β) is appropriately flown from the upstream side of the air passage. Is to measure the fluid force generated on the hull.

On the other hand, numerical analysis using a CFD solver,
In so-called CFD analysis, an air path similar to that in a wind tunnel experiment is formed in a virtual space in a computer, and a car carrier to be tested is installed inside the air path so that the bow faces the upstream side of the air path. The fluid force generated in the hull is analyzed by a simulation in which winds with different wind directions flow from the flow side. At this time, it is assumed that there is no friction on the air passage wall surface, and that a complete uniform flow will flow in from the air passage inlet.

The main dimensions of the car carrier to be tested are shown in [Table 1]. This [Table 1] shows the vertical line length Lpp, ship width B (mld.), Depth D (mld.)
It shows the draft d when the ballast is loaded, the freeboard f when the ballast is loaded, the representative area (= B × f) and the representative length (= Lpp).

[0023]

[Table 1]

In the wind tunnel experiment, an automobile carrier of the conventional structure having the above main dimensions (hereinafter referred to as a prototype ship)
With respect to this prototype ship, each notch step portion 18 has a depth g of 2.2 m (about 8.6% of the freeboard f) and a width of 1.8 m.
A car carrier (hereinafter referred to as a final type ship) of the present embodiment in which a and 18b and an inclined surface 20 having an angle of 38 degrees (deg.) with respect to the horizontal plane are formed was used.

In the CFD analysis, in addition to the prototype ship and the final ship, only the angle of the inclined surface 20 with respect to the final ship is 20 degrees (deg.), 45 degrees (deg.), And 60 degrees (deg.), Respectively. .)
And a car carrier set at 90 degrees (deg.) Was used.

The hydrodynamic forces obtained in the wind tunnel experiment and the CFD analysis are summarized as hydrodynamic forces in a fixed hull coordinate system, with the center of the waterline of the hull of the automobile carrier being the experiment as the origin. The coordinate system is shown in FIG. The obtained fluid force was summarized by the dimensionless coefficient shown below.

The resistance coefficient: CFx = Fx / q · A lateral force coefficient: CFy = Fy / q · A yaw moment coefficient: CMz = Mz / q · A · L where, q: dynamic pressure (= ρV ^2/2 ) Ρ: Air density V: Relative wind speed to the ship A: Representative area (= ship width B × freeboard f) L: Representative length (= perpendicular length Lpp).

The results of the wind tunnel experiment for the final type ship are shown in [Table 2], and the results of the wind tunnel experiment for the prototype ship are shown in [Table 3].
The CFD analysis results for the final type ship are shown in [Table 4], and the CFD analysis results for the prototype ship are shown in [Table 5].
[Table 2] to [Table 5] show resistance coefficient CFx, lateral force coefficient CFy, and yaw moment coefficient CMz for various relative wind direction β degrees.
Is shown.

[0029]

[Table 2]

[0030]

[Table 3]

[0031]

[Table 4]

[0032]

[Table 5]

The fluid force coefficients of the prototype ship and the final ship will be analyzed below based on these results.

(1) Resistance Coefficient CFx The relationship between the resistance coefficient CFx with respect to the relative wind direction β of the wind tunnel test result and the CFD analysis result for the prototype ship and the wind tunnel test result and the CFD analysis result for the final ship is shown in FIG.

According to the results obtained by the wind tunnel experiment and the CFD analysis, the resistance coefficient CFx of the final type ship was smaller than that of the prototype ship in all the relative wind directions analyzed. In the CFD analysis, the reduction rate of the resistance coefficient CFx of the final type ship to the prototype ship in each relative wind direction is about 18% in the relative wind direction 0 degree (deg.), And the relative wind direction 20 degree (deg.).
About 21% in relative wind direction about 30 degrees (deg.) About 1%
It was 9%. In the wind tunnel experiment, the relative wind direction was 0.
The degree of reduction in degrees (deg.) Is about 20%, and the relative wind direction is 20 degrees (d
eg.), the reduction rate was about 20%, and the reduction rate at a relative wind direction of 30 degrees (deg.) was about 22%, and the resistance coefficient CFx of the final type ship was smaller than that of the prototype ship.

When the CFD analysis result and the wind tunnel test result are compared, the CFD analysis result shows that the resistance coefficient CFx is larger than that of the wind tunnel test result, but the reduction rate for the relative wind direction is relatively qualitatively. It showed a good agreement.

(2) Lateral Force Coefficient CFy The relationship between the lateral force coefficient CFy and the relative wind direction β of the wind tunnel test result and CFD analysis result for the prototype ship and the wind tunnel test result and CFD analysis result for the final ship is shown in FIG. Show.

According to the results obtained by the wind tunnel experiment and the CFD analysis, the lateral force coefficient CFy of the final type ship was smaller than that of the original type ship in all the relative wind directions analyzed. In the CFD analysis, the reduction rate of the lateral force coefficient CFy of the final type ship with respect to the prototype ship in each relative wind direction is about 13% in the relative wind direction 20 degrees (deg.), And the relative wind direction 30 degrees (de
g.) was about 19%. Also, in the wind tunnel experiment, the reduction rate at a relative wind direction of 20 degrees (deg.) Was about 19%,
The reduction rate at a relative wind direction of 30 degrees (deg.) Was about 21%, and although there was some difference in the reduction rate, the lateral force coefficient CFy was reduced in the final type ship than in the prototype ship.

(3) Yaw moment coefficient CMz The relationship between the yaw moment coefficient CMz and the relative wind direction β of the wind tunnel test result and CFD analysis result for the prototype ship and the wind tunnel test result and CFD analysis result for the final ship is shown in FIG. Show.

According to the results obtained by the wind tunnel experiment and the CFD analysis, the yaw moment coefficient CMz of the final type ship was smaller than that of the original type ship at a relative wind direction of 20 degrees (deg.) Or more. In the CFD analysis, the reduction rate of the yaw moment coefficient CMz with respect to the prototype ship of the final type ship in each relative wind direction is about 21% in the relative wind direction 20 degrees (deg.) And about 21% in the relative wind direction 30 degrees (deg.). %Met. Also, in the wind tunnel experiment, the reduction rate at a relative wind direction of 20 degrees (deg.) Was about 12%, the reduction rate at a relative wind direction of 30 degrees (deg.) Was about 12%, and the CFD analysis result was better than the wind tunnel experiment result. Although the difference due to the change in hull form is also highly evaluated, the size relationship of the yaw moment coefficient CMz due to the difference in relative wind direction and shape can be roughly grasped in any case.

Next, regarding the prototype ship and the final model ship, CF
Consider the wind flow field information obtained by D analysis. Figure 4
As shown in, when wind is blown to the prototype ship and the final model ship with the course in the X direction from the left diagonal forward (relative wind direction β = 20 degrees), the prototype ship and the final model ship are on the starboard downstream side of the hull. There is a large difference in the size of the region where the flow velocity becomes slower on the side. In the prototype ship, the region where the flow velocity slows down due to eddies and separation created by the hull extends to the downstream side of the starboard side of the hull. Generally, the larger the area where the flow velocity becomes slower, the larger the wind pressure resistance becomes. The final type ship has a notch step 18a formed on the side of the ship,
Due to the inclined surface 20 formed on the bow portion 18b and the bow portion, the region where the flow velocity becomes slow is small, and the effect of improving the resistance can be seen.

Similarly, to the left diagonally forward (relative wind direction β = 2
Looking at the flow velocity distribution on the bow when a wind is blown from 0 degree), there is a large difference in the flow velocity on the upper deck surface of the bow between the prototype ship and the final ship. Comparing the flow velocity on the upper deck surface of the bow,
The prototype ship has a much slower flow velocity than the final model ship. In the prototype ship, the flow velocity seems to have slowed down due to the separation of the flow at the edge of the bow, which can be considered to be the cause of the deterioration in resistance. Since the final type ship has the inclined surface 20 that is upward with respect to the horizontal plane at the bow portion, the flow velocity is sufficiently high in this part and separation is unlikely to occur, so wind pressure resistance can be reduced.

Similarly, diagonally to the left front (relative wind direction β =
Looking at the flow velocity distribution on the side of the ship when the wind is blown from 20 degrees), there is a large difference between the prototype ship and the final ship in the presence or absence of vortices generated on the upper deck 14-1. If a vortex occurs,
As compared with the case where no vortex is generated, a loss due to the secondary flow due to the vortex occurs, which causes an increase in wind pressure resistance. A large vortex is generated on the prototype ship, but no large vortex is generated on the final model ship. This effect is considered to be achieved by the final type ship having notches at both corners connecting the upper deck of the hull and the starboard sides.

Finally, the angles of the bow slope 20 of the final type ship with respect to the horizon are 20 degrees (deg.) And 45 degrees (de), respectively.
g.), 60 degrees (deg.) and 90 degrees (deg.) are used to carry out the CFD analysis using a car carrier, and Table 6 shows the results. [Table 6] shows the resistance coefficient CFx, the lateral force coefficient CFy, and the yaw moment coefficient CMz at a relative wind direction of 20 degrees (deg.) For each of various inclined surface angles (bow inclination angle).

[0045]

[Table 6]

According to the result obtained by the CFD analysis, the resistance coefficient CFx increases as the angle of the inclined surface 20 with respect to the horizontal line increases, but when the angle becomes 45 degrees (deg.) Or more, the resistance coefficient CFx increases greatly. Especially 60 degrees (d
The increase is remarkable in the range of 90 degrees (deg.) over eg.). On the other hand, it can be confirmed that there is no significant difference at an angle of 45 degrees (deg.) Or less. On the other hand, it can be confirmed that the lateral force coefficient CFy and the yaw moment coefficient CMz are not significantly different even if the angle of the inclined surface 20 with respect to the horizontal line is different.

Further, the wind flow field information obtained by the CFD analysis will be examined for each car carrier having different angles of the inclined surface 20. In an automobile carrier with the angle of the sloping surface 20 with respect to the horizontal plane being 90 degrees (deg.), The region where the flow is separated on the upper deck 14-1 can be confirmed as in the case of the prototype ship described above. The angle of the inclined surface 20 is 60 degrees (d
Even in the case of eg.), some signs of peeling can be recognized, but when the angle of the inclined surface 20 is 45 degrees (deg.) or less, almost no sign of peeling is seen. That is, the inclined surface 20
If the angle is less than 45 degrees (deg.), There is no big difference in the resistance coefficient CFx.

From the results of the wind tunnel experiment and CFD analysis described above, the following matters can be confirmed.

The final type ship can achieve reduction of the resistance coefficient CFx with respect to the original type ship. The reduction rate is relative wind direction β =
It is about 20% at 0, 20, and 30 degrees (deg.).

The final type ship can achieve reduction of the lateral force coefficient CFy with respect to the original type ship. The reduction rate is relative wind direction β =
At 20 and 30 degrees (deg.), It is about 20%.

The final type ship can achieve reduction of the yaw moment coefficient CMz with respect to the original type ship. The reduction rate is about 10-20 at relative wind direction β = 20, 30 degrees (deg.).
%.

The relationship between the angle of the inclined surface 20 formed on the bow portion with respect to the horizontal plane and the resistance coefficient CFx increases with an increase in the angle, and when the angle becomes 45 degrees (deg.) Or more, the increase in the resistance coefficient CFx increases. , Especially over 60 degrees (deg.) 9
The increase is remarkable in the range of 0 (deg.) Degrees, but 45 degrees
There is no big difference at angles less than (deg.). On the other hand, the lateral force coefficient CFy and the yaw moment coefficient CMz are not significantly different even if the angle of the inclined surface 20 with respect to the horizontal plane is different.

The present invention is not limited to a car carrier,
By applying it to cargo ships such as container ships, tankers, passenger ships, etc., it is possible to reduce resistance due to wind pressure, lateral force, and yaw moment. By reducing the lateral force and yaw moment, it is possible to reduce the amount of rudder and the required rudder amount, and also to reduce the underwater resistance.

Further, in the above-mentioned embodiment, the notch step portion 18a is formed on both corner portions 17a and 17b connecting the upper deck 14-1 of the hull 11 and the starboard side portions 16a and 16b, respectively, over substantially the entire length from the bow 12 to the stern 13. , 18b are provided,
Even if a similar notch step portion is provided over the range from the bow to almost the center of the hull, substantially the same operational effect can be obtained. That is, in order to reduce the oblique navigation under wind pressure, it is sufficient to reduce at least one of the lateral force and the yaw moment as described above. Lateral force acts forward (on the bow side) of the center of the hull when wind is received from diagonally forward. The acting position of the lateral force is obtained by dividing the yaw moment Mz by the lateral force Fy. For example, from the wind tunnel test results for the final type ship shown in [Table 2], when the relative wind direction is 20 degrees (deg.), The yaw moment coefficient CMz is 0.398 and the lateral force coefficient CFy is 1.920. Therefore, the lateral force acting position (CMz
/ CFy) becomes 0.21. That is, at this time, the lateral force acts on the position 0.21 L ahead of the center of the hull. Therefore, if the lateral force acting on the first half of the hull is reduced, the yaw moment due to this may be further reduced. For this reason, it is also effective to install the notch step only in the first half of the hull.

[0055]

As described in detail above, according to the present invention, a ship having a hull structure capable of reducing resistance due to wind pressure, lateral force, and yaw moment, a small diagonal angle, and a small underwater resistance acting on the hull. Can be provided.

[Brief description of drawings]

FIG. 1 is a schematic view of a ship form of an automobile carrier according to an embodiment of the present invention.

FIG. 2 is a schematic vertical cross-sectional view of a portion of the hull of the vehicle carrier that is provided with a notch step portion, taken along the width direction.

FIG. 3 is a side view and a top view of a bow portion of the automobile carrier.

FIG. 4 is a diagram showing a coordinate system used for explaining a wind tunnel experiment and a CFD analysis.

FIG. 5 is a diagram showing the relationship between the resistance coefficient CFx with respect to the relative wind direction β in the wind tunnel test result and the CFD analysis result for the prototype ship and the wind tunnel test result and the CFD analysis result for the final ship.

FIG. 6 is a diagram showing the relationship between the lateral force coefficient CFy and the relative wind direction β of the wind tunnel test result and the CFD analysis result for the prototype ship, and the wind tunnel test result and the CFD analysis result for the final ship.

FIG. 7 is a diagram showing the relationship between the yaw moment coefficient CMz and the relative wind direction β of the wind tunnel test result and the CFD analysis result for the prototype ship and the wind tunnel test result and the CFD analysis result for the final ship.

FIG. 8 is an explanatory diagram of resistance acting on a ship.

FIG. 9 is a diagram showing a relationship between wind direction and a ship.

[Explanation of symbols]

11 ... Hull 12 ... Bow 13 ... Stern 14-1 ... Upper deck 15 ... Ship 16a, 16b ... port side 17a, 17b ... Corners 18a, 18b ... Notch step 20 ... Inclined surface

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshikazu Tanaka             2-1-1 Toranomon, Minato-ku, Tokyo Stock market             Company Merchant Ship Mitsui (72) Inventor Koichiro Matsumoto             1-2-1, Marunouchi, Chiyoda-ku, Tokyo             Main Steel Pipe Co., Ltd.

Claims (6)

[Claims] 1. A ship characterized by being provided with notched steps over substantially the entire length from the bow to the stern, at both corners connecting the upper deck of the hull and the starboard sides. 2. A ship characterized in that notched step portions are provided at both corners connecting the upper deck of the hull and the starboard side parts, respectively, over a range from the bow to approximately the center of the hull. 3. The ship according to claim 1, wherein the depth from the upper deck of the notched step portion is set to 5 to 20% of the freeboard when the ballast is loaded. 4. The ship according to claim 1, wherein the bow portion is formed with an inclined surface which is upward with respect to a horizontal plane from the upper end of the front edge of the bow toward the upper deck. 5. The ship according to claim 4, wherein the upward angle of the inclined surface with respect to the horizontal plane is set to 20 to 60 degrees. 6. The ship according to claim 4, wherein the upward angle of the inclined surface with respect to the horizontal plane is set to approximately 38 degrees.