JP5101680B2 - Stern fin - Google Patents

Description

  The present invention relates to a stern fin of a low-speed enlargement ship such as a bulk carrier or a tanker having a square coefficient (cb) exceeding 0.8.

  Conventionally, as this type of stern fin structure, there is known a structure in which rectifying fins are attached to both sides of a hull outer plate in front of a stern propeller. The present applicant has proposed a stern fin structure of this type described in Japanese Patent Application Laid-Open No. 2004-42881. The proposal described in Japanese Patent Application Laid-Open No. 2004-42881 relates to the invention name “asymmetric stern fin structure”, “by canceling the specific resistance of the fin, reducing the hull resistance, and at the same time generating an asymmetric flow to the propeller. For the purpose of “providing an asymmetric stern fin structure with improved self-propelled elements” (see paragraph number 0008 of the same publication), “in the stern fin structure, one surface is configured as a flat surface and the other surface is The stern fins with a cross-sectional shape that decreases in thickness from the hull mounting part toward the open end side are arranged on both right and left sides with the flat surfaces facing the propeller rotation direction, and the hull mounting of the stern fins The side elevation angle of the portion is set to a predetermined value, the rear end height of the stern fin is arranged in a range of 60 to 70% of the propeller radius, and the rear end of the stern fin is substantially 0. By arranging it in the vicinity of the position of 5 stations "(see claim 1 of the same publication)," the propeller thrust is assisted and the hull resistance and self-propelled elements are improved by a predetermined value. In addition, with the structure in which the starboard stern fin is retracted by a predetermined position and the left and right positions are shifted, the thrust reduction coefficient of the self-propelled element is further improved. (See paragraph number 0032 of the publication).

FIG. 4 is a drawing attached to the same publication as FIG. 1, and is a side view showing the asymmetric stern fin structure according to the first embodiment disclosed in the publication. In FIG. 1 shows an overall outline of an asymmetric stern fin structure according to the first embodiment disclosed in the publication, 103 is a ship, 105 is a stern, and 107a is a stern fin according to the first embodiment disclosed in the publication. , 109 is a propeller, and 111 is a rudder. L1 represents the velocity of the fluid flowing on the flat surface side of the stern fin 7a, L2 represents the velocity of the fluid on the thick side of the stern fin 107a, and A. P, stern perpendicular (rudder center position), ST1.0 is A. P. The position of 10% of Lpp (length between perpendiculars) from the (stern perpendicular) to the bow side, ST0.5 is P. The position of 5% of Lpp (length between perpendiculars) is shown from the (stern perpendicular) to the bow side.

  The applicant of the present application has further studied the water flow around the stern, and has intensively studied why the already proposed “asymmetric stern fin structure” reduces the separation of the water flow to the propeller 109.

5 (a) and 5 (b) show the principle of generation of water flow separation to the propeller 109 described above (FIG. 5 (a)) and the arrangement of the asymmetric stern fins of a predetermined shape at a predetermined position of the stern, It is a principle figure which shows the principle (FIG.5 (b)) of preparing a water flow and preventing generation | occurrence | production of peeling. That is, in the hull stern without the proposed “asymmetric stern fin”, the water flow to the propeller 109 has a detrimental effect on the self-propelling element as a result of the separation caused by the stern shape. By arranging the asymmetrical stern fins, it was found that the water flow to the propeller 109 was adjusted, and peeling that occurred near the propeller 109 was prevented.
However, while studying the improvement of the stern flow that flows into the propeller 109, it was found that the stern flow is less likely to be separated in the improved stern that can improve the stern flow by repeatedly improving the stern flow itself. .

FIG. 6 (a) is a schematic diagram of a conventional normal stern with no stern flow improvement, and FIG. 6 (b) is a schematic diagram of a stern with improved stern flow. Both are views seen from the stern direction. 6 (a) and 6 (b), the thick arrows indicate the flow from the hull.
As shown in FIGS. 6 (a) and 6 (b), this improved stern has a height in the range of 60 to 70% of the propeller radius of the hull stern and is in the vicinity of the 0.5 station position. The stern is narrowed down toward the center of the hull.

  At a height in the range of 60-70% of the propeller radius and at the 0.5 station position, the improved stern will accelerate the flow to the propeller at this position. That is, as described above, as a result of examining the stern water flow as described above, in the conventional normal stern type stern, the water flow separation occurs most in the flow from the bottom to the top of the propeller. By rectifying, it is possible to reduce propulsion and eddy resistance by rectification and acceleration, and improve propulsion performance.

  And even if it is a stern that is difficult to cause such water flow separation, it is possible to further rectify the turbulent water flow in front of the propeller or increase the water flow to efficiently flow into the propeller. Specifically, in place of the stern fins already proposed by the applicant of the present application, how to further reduce separation, decrease vortex resistance, improve propulsion performance, etc. by rectification and acceleration We investigated the position of the stern fins of various shapes and sizes on the stern of the hull by water tank experiments.

As a result of the investigation, the improved stern has a height in the range of 60 to 70% of the propeller radius of the hull stern as described above, and the vicinity of the 0.5 station position is narrowed down toward the center of the hull. It has been found that even if the asymmetric stern fins already proposed by the applicant are arranged, the effect of the asymmetric stern fins is difficult to obtain.
Therefore, as a result of pursuing effective stern fins for such an improved stern, the height of the propeller radius of the hull stern as described above is in the range of 60 to 70% and 0.5 station. Even if it is a stern that narrows the vicinity of the position toward the center of the hull, if it is a low-speed enlargement ship such as a bulk carrier or tanker with a square factor (Cb) exceeding 0.8, a predetermined shape at a predetermined position on the stern It has been found that by arranging the stern fins, the flow into the propeller can be controlled and the self-propulsion element can be improved.

JP 2004-42881 A

  In the present invention, a rectangular coefficient (Cb) exceeds 0.8 and a low-speed enlargement ship such as a bulk carrier or a tanker having a stern that narrows the vicinity of the 0.5 station position toward the center of the hull flows into the propeller. It aims at providing the stern fin which controls the flow to improve and improves the self-propulsion element.

  In the invention according to claim 1 of the present invention, in a low-speed enlargement ship such as a bulk carrier or a tanker having a stern with a square factor (Cb) exceeding 0.8 and narrowing the vicinity of the 0.5 station position toward the center of the hull, It has a trapezoidal cross section with a length of 2-3% Lpp and a thickness of 100-150mm, where the upper base is shorter than the lower base. A stern fin, where the rear end position of the stern fin coincides with the stern profile matched to the stan frame position of the hull, and at a height position in the range of 80 to 90% of the propeller diameter (B.L. .) Is provided in parallel.

Since this invention is comprised as mentioned above, there exists an effect described below.
In the navigation speed range (near Fn = 0.17) of the low-speed enlargement ship, the flow flowing into the propeller is controlled by the stern fin to improve the self-propulsion element. This has the effect that the required horsepower when navigating at the same speed can be reduced by 1.0 to 1.5%. (See Figure 3)

FIG. 1 is a schematic view of arrangement of a stern fin 1 according to a first embodiment to a hull stern. FIG. 2 is a diagram showing the movement of water flow to the propeller when the stern fins 1 according to the first embodiment are arranged on the hull stern. A hull provided with stern fins 1 according to the first embodiment, a hull provided with asymmetric stern fins described in Japanese Patent Application Laid-Open No. 2004-42881 already proposed by the present applicant, and a hull not provided with these additions The horsepower-speed graph showing the horsepower reduction effect of the horsepower reduction measured by an aquarium experiment, FIG. 4 is a side view showing the asymmetric stern fin structure according to the first embodiment disclosed in Japanese Patent Application Laid-Open No. 2004-42881 as FIG. 5 (a) and 5 (b) show the principle of generation of water flow separation to the propeller 109 described above (FIG. 5 (a)) and the arrangement of the asymmetric stern fins of a predetermined shape at a predetermined position of the stern, A principle diagram showing the principle (Fig. 5 (b)) of adjusting the water flow and preventing the occurrence of peeling. FIG. 6 (a) is a schematic diagram of a conventional normal stern with no stern flow improvement, and FIG. 6 (b) is a schematic diagram of a stern with improved stern flow.

  An embodiment of the best mode for carrying out the stern fin according to the present invention will be described in detail with reference to the drawings.

1 and 2 are views showing Example 1 of a stern fin which is an example of a form for carrying out the stern fin according to the present invention. Of these, FIG. 1 shows the stern fin according to Example 1. FIG. 1 is a schematic diagram of the arrangement of the stern fin 1 on the hull stern, and FIG. 2 is a diagram showing the movement of the water flow to the propeller when the stern fin 1 according to the first embodiment is arranged on the stern of the hull.
1 and 2, reference numeral 1 is a stern fin according to the first embodiment, 3 is a hull stern, 9 is a propeller, and 11 is a rudder. A. P. Is the stern perpendicular (the rudder center position); L. Indicates the baseline, and the thick arrow indicates the stern water flow sucked into the propeller 9.

As shown in FIGS. 1 and 2, the stern fin 1 according to the first embodiment of the trapezoidal shape having a length of 2 to 3% Lpp is adjusted so that the rear end position of the stern fin 1 matches the stan frame position of the hull. It matches with the stern profile and is provided at a height position of 80 to 90% of the diameter of the propeller 9 in parallel with the base line (BL).
Further, the stern fin 1 according to the first embodiment has a trapezoidal cross section with a thickness of 100 to 150 mm whose upper bottom is shorter than the lower bottom by 200 to 300 mm, and its protruding width is about 1 m from the side of the hull. It is what you have.

Explaining this in relation to the installation position of the conventional asymmetric stern fin, the stern fin 1 according to the first embodiment is closer to the propeller 9 than the position where the conventional asymmetric stern fin is disposed. They are attached to each stern side parallel to the base line (BL) symmetrically with respect to the center. In addition, as a material, the stern fin 1 which concerns on the present Example 1 is manufactured with steel.
As shown in FIG. 2, the stern fin 1 according to the first embodiment disposed at such a position causes the water flow (indicated by an arrow in FIG. 2) flowing through the stern to be propelled by the propeller 9 most. Can be concentrated and flowed in the vicinity of 0.7R, which can improve the self-propulsion element of the ship.

  As described above, as shown in FIGS. 1 and 2, the stern fin 1 according to the first embodiment is more suitable than the asymmetric stern fin described in Japanese Patent Laid-Open No. 2004-42881 that the applicant of the present application has already proposed. The stern fin 1 is made of steel and has a length of 2 to 3% Lpp. The stern fin 1 is made of steel and is symmetrical to the position close to the propeller 9 and parallel to the base line (B.L.). A fin-shaped stern fin 1 having a trapezoidal cross section having a thickness of 100 to 150 mm shorter than the bottom bottom, and the stern fin 1 according to the first embodiment has a stern at the rear end position of the stern fin 1 having this shape. It matches with the profile and is provided at a height position of 80 to 90% of the diameter of the propeller 9 in parallel with the base line (BL).

Since the stern fin 1 according to the first embodiment is disposed at the above position, the stern flow (indicated by a thick arrow in FIG. 2) sucked into the propeller 9 is generated by the propeller 9 that generates the most thrust. It becomes possible to concentrate and flow in the vicinity of 0.7R, thereby improving the ship's self-propulsion element.
Moreover, since the length of the fin is as short as 2-3% of the length between the perpendiculars (Lpp), the specific resistance of the stern fin 1 itself can be suppressed.

FIG. 3 shows a hull provided with the stern fin 1 according to the first embodiment, a hull provided with the asymmetric stern fin described in Japanese Patent Application Laid-Open No. 2004-42881, which has already been proposed by the applicant of the present application, and these additions. It is a graph of horsepower-speed which shows the horsepower reduction effect which measured horsepower reduction by the tank experiment between the hull which does not provide.
In FIG. 3, the horizontal axis represents speed (knots), the vertical axis represents horsepower (kw), the solid line represents a hull graph with no appendages, and the wavy line represents an asymmetric stern fin described in JP-A-2004-42881. The hull graph and dotted line show the hull graph provided with the stern fin 1 according to the first embodiment, and the thin line shows the normal output of the hull.
As is clear from FIG. 3, the hull provided with the stern fin 1 according to the first embodiment in the vicinity of the normal output (thin line) is described in Japanese Patent Application Laid-Open No. 2004-42881 that has already been proposed by the present applicant. Compared to a hull provided with asymmetric stern fins, there was a horsepower reduction effect of 1.0 to 1.5%.

  The stern fin according to the present invention can be used for a low-speed enlargement ship such as a bulk carrier or a tanker having a square coefficient (Cb) exceeding 0.8.

DESCRIPTION OF SYMBOLS 1 Stern fin 3 Hull stern 9 Propeller 11 Rudder 101 Asymmetrical stern fin structure 103 based on 1st Embodiment disclosed by Unexamined-Japanese-Patent No. 2004-42881 Ship 105 Stern 107a 1st disclosed by Unexamined-Japanese-Patent No. 2004-42881 Stern fin 109 propeller 111 rudder L1 according to the embodiment of the present invention L1 velocity L2 of fluid flowing on the flat surface side of the stern fin 107a L2 velocity of fluid on the thick side of the stern fin 107a P. Stern vertical line (rudder center position)
Lpp hull length (length between perpendiculars)
B. L. Baseline ST1.0 A. P. Position ST0.5 at 10% of Lpp (length between perpendiculars) from the (stern perpendicular) to the bow side. P. 5% position of Lpp (length between perpendiculars) from (stern perpendicular) to bow side

Claims (1)

In low-speed enlargement vessels such as bulk carriers and tankers with a stern with a square factor (Cb) exceeding 0.8 and narrowing the vicinity of the 0.5 station position toward the center of the hull, the length is 2-3% Lpp. A stern fin having a trapezoidal cross-section with a thickness of 100 to 150 mm shorter than the bottom bottom, and a stern fin having a protruding width of about 1 m from the side of the hull provided symmetrically with respect to the center of the hull. The rear end position is adjusted to the stern frame position of the hull to match the stern profile and parallel to the base line (BL) at a height position in the range of 80 to 90% of the propeller diameter. Features a stern fin.

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