JP4116986B2 - Stern structure in high-speed ship - Google Patents

Description

  The present invention relates to a stern structure in a high-speed ship. More specifically, the present invention relates to a stern structure in a high-speed ship that navigates at a speed at which the fluid number is 0.25 or more.

It is known that air resistance, friction resistance, and other resistance (residual resistance) act on the hull when the ship sails. Reducing these resistances can improve the navigation performance of the ship. Important to the stability of the hull.
In ordinary ships, air resistance is small and negligible compared to other resistances, so it is necessary to reduce frictional resistance and residual resistance. However, wave resistance included in residual resistance is proportional to the square of speed. Therefore, if the speed of the ship increases, the influence of wave resistance becomes stronger. In particular, in high-speed ships with a fluid number of 0.25 or more, it is important to reduce the wave-making resistance because the wave-making resistance contained in the residual resistance accounts for the majority of the resistance.

As a method for reducing the wave-making resistance of a high-speed ship, there are techniques described in Conventional Examples 1 to 3 (Patent Documents 1 to 3).
The techniques of Conventional Examples 1 to 3 are techniques for reducing wave-making resistance by providing trim tabs and wedges on the bottom of the stern. Conventional Examples 1 and 2 are based on the lift generated by the trim tabs and the like. The conventional example 3 accelerates the water flow in the wedge portion and causes the accelerated water flow to flow horizontally or downward in order to reduce the wave-making resistance by reducing the amount of stern submergence. This technology reduces resistance.

However, the effect of lifting the stern end by the lift generated by the trim tab, etc. can only be obtained with an ultra-high speed and small high-speed ship with a fluid number of 0.4 or more, so a large high-speed ship or a high-speed fluid with a fluid number of about 0.25 to 0.4. Even if it is adopted in a ship, the effect of reducing wave resistance cannot be obtained.
Moreover, although the technique of the prior art example 3 can accelerate the water flow in the wedge part, it cannot reduce the wave forming resistance because it cannot reduce the area where waves are formed at the stern. In addition, since a very slow flow is formed in front of the wedge part compared to a ship with a normal stern shape, even if wave resistance can be reduced, the propulsion power of the ship is reduced and a large energy loss occurs. May occur. And since the stern must be made into a special shape, it takes time and effort to manufacture, and the manufacturing cost increases.

JP-A 62-008891 JP 09-052591 A JP 2002-154475 A

  In view of the above circumstances, the present invention provides a stern structure in a high-speed ship that can reduce wave-making resistance by accelerating the flow at the stern end and rectifying the water flow behind the propeller for propulsion, and is easy to manufacture. The purpose is to do.

The stern structure in the high-speed ship according to the first aspect of the present invention includes a stern additional member disposed on the stern side of the stern counter located above the propeller for propulsion on the stern side of the propeller for propulsion. The pair of fins are provided so as to sandwich the extension line passing through the propeller shaft for propulsion from both sides when the bottom of the ship is viewed from below, and the pair of fins have their bow and stern side ends at the propulsion. It arrange | positions back from the propeller for use, and it is arrange | positioned so that the space | interval of both may become narrow toward a stern side from a bow side.
The stern structure in the high-speed ship according to the second invention is characterized in that, in the first invention, the distance from the blade base to the blade edge of the pair of fins is increased from the bow side toward the stern side. To do.
Stern structure in high-speed vessels of the third invention, in the first invention, at the time of sailing ship, the cutting edge of the pair of fins, characterized in that it is formed so as to intersect the water line.

According to the first invention, the water flow behind the propeller for propulsion formed by the propeller for propulsion can be collected by the pair of fins. Then, the water flow discharged from the stern end can be accelerated, and the area where waves are formed at the stern end can be narrowed, so the wave-making resistance caused by the waves formed at the stern end is reduced. can do. Further, since the accelerated water flow can be discharged from the narrow region at the stern end, the propulsive force by the water flow discharged from the stern end can be increased, and the effect of accelerating the ship can be obtained. And since it only attaches a pair of fin to the ship which has a normal stern shape, manufacture is easy and manufacturing cost can also be reduced. Moreover, the pair of fins can prevent the flow ahead of the propeller for propulsion from being disturbed.
According to the second invention, the resistance due to the bow side portion can be reduced, and the rectifying effect at the stern end can be strengthened.
According to the third invention, the entire fins of a pair is not submerged, it is possible to reduce the resistance by the pair of fins. In addition, since the generation of waves can be suppressed by the opposing surfaces of the pair of fins, the wave resistance can be reduced.

Next, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is an enlarged view of a stern of a high-speed ship provided with the stern structure of the present embodiment, where (A) is a side view and (B) is a bottom view. FIG. 2A is a view of a high-speed ship provided with the stern structure of the present embodiment as viewed from the stern end, and FIG. 2B is an enlarged view of the fin 10. 1 and 2, reference numeral 2 indicates a stern counter of the high-speed ship 1. Below this stern counter 2, a propeller 3 for propulsion of a high-speed ship is disposed. The propeller 3 for propulsion is fixed to the end of the propeller shaft 3a for propulsion whose boss 3b is connected to the engine. A rudder 4 is provided behind the propeller 3 for propulsion.

  As shown in FIGS. 1 and 2, a pair of fins 10, 10 are provided on the bottom 2 a of the stern counter 2 above the propeller 3 for propulsion and behind the propeller 3 for propulsion. It has been. The pair of fins 10 and 10 sandwich the extension line CL passing through the central axis of the propeller shaft 3a for propulsion from both sides when the bottom 2a of the stern counter 2 is viewed from below the bottom 2a. They are arranged so that the distance between them becomes narrower from the bow side toward the stern side.

For this reason, the water flow behind and above the propeller 3 formed by the propeller 3 can be collected by the pair of fins 10 and 10 toward the center in the width direction of the hull. If it is FIG. 1 (B), a water flow can be collected toward the extension line CL. Then, since the water flow discharged from the stern end can be accelerated, the wave height generated at the stern end can be suppressed.
And since a pair of fins 10 and 10 are small in shape and do not interfere with the rudder 4, even if the pair of fins 10 and 10 are provided, the navigation of the ship is not adversely affected.

  In addition, the portion where the stern end is immersed in water can be narrowed to the distance between the pair of fins 10 and 10 on the stern side. If it is FIG. 1 (B), although the part between the two lines WL which shows the waterline in navigation will be a part immersed in water, it will be immersed in water compared with the width of a stern end at the stern end. The part becomes narrower. Therefore, since the region where the waves are formed at the stern end can be suppressed to the interval between the pair of fins 10 and 10 on the stern side, it is possible to reduce the wave resistance caused by the waves formed at the stern end. it can.

  Further, since the water flow flowing along the bottom 2a of the stern counter 2 can be accelerated behind the propeller 3 for propulsion, the water flow in the slow water flow region formed in the vicinity of the bottom 2a of the stern counter 2, that is, a so-called dead water region. Can also accelerate. Then, since the flow of water behind the propeller 3 for propulsion becomes smooth, the driving force generated by the propeller 3 for propulsion can be effectively converted into the water flow flowing behind the hull, and energy loss can be reduced.

Further, the accelerated water flow can be discharged from the narrow region at the stern end, and the driving force generated by the propeller 3 for propulsion can be effectively converted into the water flow flowing to the rear of the hull, so that it is discharged from the stern end. The driving force by the water flow can be increased.
And since only a pair of fins 10 and 10 are attached to the stern of the high-speed ship 1 which has a normal stern shape, manufacture is easy and manufacturing cost can also be reduced.

As shown in FIG. 2, the pair of fins 10, 10 has a substantially triangular cross section, and one surface 10 b (hereinafter referred to as a blade base 10 b) is attached to the bottom 2 a of the stern counter 2. Yes. The distance L from the blade base 10b to the side 10c (hereinafter referred to as the blade tip 10c) facing the blade base 10b is formed so as to increase from the bow side toward the stern side.
For this reason, since the contact area of the bow side part and water in a pair of fins 10 and 10 can be made small, the frictional resistance and vortex resistance which arise by a pair of fins 10 and 10 can be reduced, and in the stern end The rectifying effect can be strengthened. And if the contact area of the bow side part and water in a pair of fins 10 and 10 is made small, the influence which a pair of fins 10 and 10 has on the water flow ahead rather than the propeller 3 for propulsion can also be reduced, It is possible to prevent disturbance of the water flow ahead of the propeller 3 for propulsion.
In particular, if the tips of the pair of fins 10 and 10 are disposed so as to be located rearward (stern side) of the rear end of the boss 3b of the propeller 3 for propulsion, the water flow is more forward than the propeller 3 for propulsion. This can further reduce the effect.

As shown in FIG. 2A, in the pair of fins 10, 10, the surfaces 10a facing each other are inclined with respect to the water surface, and the distance between the cutting edges 10c is longer than the distance between the cutting edges 10b. It is formed as follows. In other words, when viewed from the stern, the pair of fins 10 and 10 are arranged so that an eight-character shape is formed by the mutually facing surfaces 10a.
For this reason, among the water flows flowing backward from between the pair of fins 10, 10, the water flow in the vicinity of the fins 10 can be made slightly downward, so that the effect of suppressing the wave height generated at the stern end is enhanced. Can do.

The shape of the fin 10 is not limited to the shape as described above, and may be a plate shape. Even in this case, the distance from the blade edge to the blade edge increases from the bow side toward the stern side. If it is, the effect similar to the fin of the said shape can be acquired.
Furthermore, the pair of fins 10, 10 is capable of collecting the water flow behind and above the propeller 3 for propulsion toward the center in the width direction of the hull by the pair of fins 10, 10. The distance L from the blade edge to the blade edge may not be formed so as to increase from the bow side toward the stern side.
Furthermore, you may arrange | position so that the front-end | tip of a pair of fins 10 and 10 may be located ahead (the bow side) rather than the rear end of the boss | hub 3b of the propeller 3 for a propulsion.

Moreover, if a pair of fins 10 and 10 are arrange | positioned so that the blade edge | tip 10c of the fin 10 may cross | intersect a water line at the time of navigation of a ship, in other words, a pair of fins 10 and 10 whole may not be submerged. The frictional resistance and eddy resistance generated by the pair of fins 10 and 10 can be reduced. And since the disturbance of a water surface can be suppressed by the surface 10a which a pair of fins 10 and 10 oppose in the position where the blade edge | tip 10c of the fin 10 cross | intersects a water line, wave-making resistance can be reduced.
In particular, if the position where the blade edge 10c of the fin 10 intersects the draft line is located behind (stern side) the rear end of the boss 3b of the propeller 3 for propulsion, the water flow is more forward than the propeller 3 for propulsion. An adverse effect can be prevented.

Changes in the residual resistance when the number of fluids is changed in a ship having the stern structure of the present embodiment, that is, a ship having a pair of fins (Example) and a ship not having a pair of fins (Comparative Example) Compared.
In the experiment, the model ship was floated in the experimental water tank, and the flow rate of water in the experimental water tank was changed and changed in the range where the fluid number was 0.27 to 0.34, and the residual resistance was calculated from the resistance value measured by the load cell.

As shown in FIG. 3, it can be confirmed that the residual resistance of the example is smaller than the residual resistance of the comparative example in the whole range where the fluid number is 0.27 to 0.34. In particular, when the number of fluids exceeds 0.30 and the residual resistance increases, the difference between the two increases, and the maximum is 5% of the residual resistance of the comparative example and the residual resistance difference of the example is small. I can confirm that.
Therefore, if the stern structure of the present embodiment is adopted, the residual resistance can be reduced, and it can be confirmed that the effect is increased particularly in a region where the fluid number is large and the influence of the residual resistance is strong.

It is the stern enlarged view of the high-speed ship provided with the stern structure of this embodiment, (A) is a side view, (B) is a bottom view. (A) is the figure which looked at the high-speed ship provided with the stern structure of this embodiment from the stern end, (B) is the enlarged view of the fin 10. FIG. It is the figure which compared the change of the surplus resistance with respect to the fluid number with the ship provided with the stern addition member, and the ship without a stern addition member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High speed ship 2 Stern counter 2a Ship bottom 3 Propeller for propulsion 10 Fin 10a Blade edge 10c Blade edge

Claims (3)

On the stern side of the propeller for propulsion, provided with a stern additional member disposed on the bottom of the stern counter located above the propeller for propulsion,
The stern addition member is a pair of fins provided so as to sandwich an extension line passing through the propeller shaft for propulsion from both sides when the ship bottom is viewed from below.
The pair of fins is
Ends on the bow side and stern side are arranged behind the propeller for propulsion,
A stern structure in a high-speed ship, characterized in that the distance between the two is reduced from the bow side toward the stern side. 2. The stern structure in a high-speed ship according to claim 1, wherein a distance from the blade base to the blade edge of the pair of fins is increased from the bow side toward the stern side. 2. The stern structure in a high-speed ship according to claim 1, wherein the blade tips of the pair of fins are formed so as to intersect with the water line during navigation of the ship.

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