Fin device and vessel

Abstract

To provide a fin device and a vessel capable of saving energy by improving propulsion efficiency of a vessel provided with a bossing projecting downward from a bottom of a stern unit.SOLUTION: A vessel 1 is a fine type vessel including a bossing 12 projecting downward from a stern unit 11 and a hull plane unit 13 with shipboard surfaces on both quarters formed approximately in parallel from a top end to a bottom end. A fin device 2 includes a fin 21 arranged on a side surface of the bossing 12. A front end unit 22 of the fin 21 is arranged in a range of a bilge height R from a bottom 16 of the hull flat surface unit 13 as well as within a range where square station S.S is 1.0 to 1.5.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a fin device and a ship, and more particularly to a fin device suitable for energy conservation in slender ships and a ship equipped with the fin device. [Background technology]

[0002] In recent years, rising crude oil prices and environmental issues such as reducing carbon dioxide emissions have led to increased demand for improved fuel efficiency for ships, resulting in a demand for even greater energy conservation. Meanwhile, bilge vortices (separation vortices) generally occur at the stern of a ship, and propulsion efficiency can be improved by recovering these bilge vortices with a propeller.

[0003] Devices that have already been proposed for recovering bilge vortices include one that places a roughly cylindrical duct just in front of the propeller (see Patent Document 1) and one that places fins on the side of the hull (see Patent Document 2).

[0004] In the duct device described in Patent Document 1, by taking in the water flow (wake) including bilge vortices into the duct, the flow of the water flow can be straightened in the axial direction, and the bilge vortices can be efficiently collected.

[0005] In addition, in the fin device described in Patent Document 2, by arranging multiple fins within a specified range at the stern, the slow-speed zone is disturbed by vortices generated by the fins, and the water flow that formed the slow-speed zone is concentrated and directed to the propeller, thereby improving propulsion efficiency. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5132140 [Patent Document 2] Patent No. 6351700 Summary of the Invention [Problem to be solved by the invention]

[0007] Ship hull forms are generally classified into full ships, which have a large coefficient of block (CB), which indicates the degree of slenderness of the hull's underwater volume, and slender ships, which have a small coefficient of block (CB). Full ships are often used, for example, in tankers and bulk carriers. Slender ships are often used, for example, in container ships.

[0008] In slender ships, locating an appendage immediately in front of the propeller, as in the duct device described in Patent Document 1, is often not installed because it has little effect in improving propulsion efficiency. Also, locating a fin close to the side flat of the hull, as in the fin device described in Patent Document 2, is effective in the slow-speed zone formed on the bottom of the stern, but it is unable to guide the slow flow that passes by the side of the bossing that protrudes downward from the bottom of the stern to the propeller.

[0009] The present invention was devised in consideration of these problems, and aims to provide a fin device and a slender ship that can improve the propulsion efficiency and achieve energy savings for ships equipped with bossings that protrude downward from the stern. [Means for solving the problem]

[0010] According to the present invention, there is provided a fin device to be installed on a slender ship having a bossing protruding downward from the stern and a hull planar portion in which the ship's side surfaces on both chords are formed substantially parallel from the upper end to the lower end, the fin device having a fin disposed on the side of the bossing, and a front end of the fin Is, Quarstation 1.0 or greater and less than 1.5 is placed within the range The fin is disposed within a range from the front end to the rear end of the hull planar portion to the bilge height. A fin device is provided.

[0011] The front end of the fin may be positioned within a range of 1.1 to 1.4 square stations.

[0012] The fin may have a wing-shaped cross section, with the rear end positioned higher than the front end.

[0013] The fin may be formed so that the width of the tip end is shorter in the length direction of the ship than the width of the base end connected to the hull.

[0014] There may be one or more leading fins located forward and above the fins.

[0015] The slender vessel has, for example, a squareness factor of 0.75 or less or 0.8 or less.

[0016] Furthermore, according to the present invention, there is provided a vessel having a fin device having any of the above-described configurations. [Effects of the Invention]

[0017] According to the fin device and ship of the present invention described above, by arranging specified fins on the sides of the bossing of a slender ship, it is possible to improve the propulsion efficiency of a ship equipped with a bossing protruding downward from the stern and achieve energy savings. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a perspective view showing a vessel equipped with a fin device according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a side view showing the stern of the vessel shown in FIG. [Figure 3] 1A and 1B are explanatory diagrams of a fin, where (A) is a side view and (B) is a plan view. [Figure 4] 1 is an explanatory diagram showing the change in the improvement effect with respect to the fin position, where (A) shows 1-t (thrust reduction coefficient) and (B) shows 1-wt (effective wake coefficient). [Figure 5] FIG. 1 is a wake distribution diagram in the propeller plane when the propeller is not operating. [Figure 6] Analysis of water flow over the side of a bossing (A) without fins and (B) with fins. [Figure 7] FIG. 1 is a perspective view showing a hull structure of a full ship as a comparative example. [Figure 8] FIG. 10 is a diagram showing an improvement rate of a vessel equipped with the fin device according to the first embodiment. [Figure 9] FIG. 10 is a perspective view showing a vessel equipped with a fin device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the present invention will be described with reference to Figs. 1 to 9. Fig. 1 is a perspective view showing a vessel equipped with a fin device according to a first embodiment of the present invention. Fig. 2 is a side view showing the stern of the vessel shown in Fig. 1. Fig. 3 is an explanatory diagram of the fin, with (A) being a side view and (B) being a plan view. For ease of explanation, as shown in Fig. 1, the lengthwise direction of the vessel is defined as the X-axis, the widthwise direction of the vessel as the Y-axis, and the vertical direction as the Z-axis.

[0020] The vessel 1 according to the first embodiment is a slender vessel equipped with a bossing 12 protruding downward from the stern 11 and a hull planar section 13 in which the sides of both chords are formed approximately parallel from the upper end to the lower end, and is equipped with, for example, a fin device 2 as shown in Figures 1 to 3(B).

[0021] The hull type of the ship 1 is generally classified into a full ship, which has a large coefficient of curvature CB, which indicates the degree of slenderness of the hull's underwater volume, and a slender ship, which has a small coefficient of curvature CB. In this specification, a slender ship is defined as a ship type with a coefficient of curvature CB of 0.75 or less or a ship type with a coefficient of curvature CB of 0.8 or less.

[0022] The squareness factor is generally expressed as the ratio of the volume of the inside of the shell plating below the waterline of a ship at a certain draft to the volume of a rectangular parallelepiped whose length, width, and height are the length of the hull, the maximum width of the inside of the shell plating of the hull, and the vertical distance from the waterline to the top of the keel, respectively.

[0023] A slender ship 1 has, for example, a shape in which the hull planar section 13 extends in parallel to the stern section 11, and the width of the stern section 11 is larger than the width of a full ship. As shown in Figure 2, a propeller 15 is disposed below the bottom 14 of the stern section 11 and behind the bossing 12, and a propeller shaft (not shown) that mainly transmits engine power to the propeller 15 is inserted inside the bossing 12. A rudder 17 is disposed behind the propeller 15.

[0024] In this specification, the hull flat section 13 refers to the port and starboard side surfaces formed approximately parallel from top to bottom, as shown in Figures 1 and 2, and is connected to the hull bottom 16 by a curved surface with a hull bilge height R. The hull bottom 16 is connected to the bottom 14 of the stern section 11 by a smoothly curved surface.

[0025] The fin device 2 has fins 21 arranged on the side surfaces of the bossing 12. For example, one fin 21 is arranged on the port side and one on the starboard side. As shown in FIG. 3(A), for example, the fin 21 has a wing-shaped cross section and has an angle of attack α so that the rear end 23 is positioned higher than the front end 22. This configuration can reduce the resistance of the fin 21 and can make it easier to guide vortices generated at the front end 22 to the propeller 15.

[0026] 3(A) and 3(B), the fin 21 has a generally trapezoidal shape in plan view, and is formed so that the width c2 of the tip end 25 is shorter in the length in the ship direction than the width c1 of the base end 24 connected to the hull. This configuration can reduce resistance caused by an increase in flow velocity on the tip end 25 side of the fin 21.

[0027] The height b (length in the width direction of the ship) of the fin 21 is set so as to fit within a range that does not exceed the width of the ship (a range that does not protrude outward beyond the hull planar portion 13). Note that the shape of the fin 21 is not limited to the configuration shown in the figures.

[0028] For example, as shown in Figure 2, the front end 22 of the fin 21 is located within the range of bilge height R from the bottom 16 of the hull flat section 13 and within the range of square station SS of 1.0 to 1.5. Square station SS refers to a vertical plane that divides the waterline length of the ship into 10 parts. In the figure, WL indicates the waterline.

[0029] The position of square station SS is quantified in the longitudinal direction (X-axis direction) of the ship, with the after perpendicular (AP) set to 0 and the forward perpendicular (FP) set to 10. In Figure 2, the positions of square stations SS = 1.0, 1.1, 1.4, 1.5, and 2.0 are shown by dotted lines.

[0030] In addition, the length in the ship's longitudinal direction (X-axis direction) from the bow perpendicular FP to the stern perpendicular AP is called the perpendicular length Lpp, and for example, the width c1 of the root portion 24 of the fin 21 is set to approximately 1.5 to 2% of the perpendicular length Lpp, and the width c2 of the tip portion 25 of the fin 21 is set to approximately 0.5 to 1.0% of the perpendicular length Lpp.

[0031] 2, the rear end 23 of the fin 21 may be located within the range of the bilge height R from the bottom 16 of the hull flat section 13. However, the rear end 23 of the fin 21 may also be located at a position beyond the range of the bilge height R.

[0032] Figure 4 is an explanatory diagram showing the change in the improvement effect depending on the fin position, where (A) shows 1-t (thrust reduction coefficient) and (B) shows 1-wt (effective wake coefficient). The test results shown in Figure 4(A) and Figure 4(B) show the results of changing the position of the fin in the longitudinal direction using a model of the stern.

[0033] The test results in Figure 4(A) are plotted with the horizontal axis representing square station SS and the vertical axis representing 1-t (thrust reduction coefficient), with the values ​​increasing from bottom to top on the vertical axis. The larger the value of 1-t (thrust reduction coefficient), the greater the improvement effect, and in Figure 4(A), a square station SS in the range of 0.5 to 1.5 is preferable.

[0034] The test results in Figure 4(B) are plotted with the horizontal axis representing square station SS and the vertical axis representing 1-wt (effective wake coefficient), with the values ​​increasing from bottom to top on the vertical axis. The smaller the 1-wt (effective wake coefficient) value, the greater the improvement effect, and in Figure 4(B), a square station SS in the range of 1.0 to 2.0 is preferable.

[0035] 1-t (thrust reduction coefficient) and 1-wt (effective wake coefficient) are self-propulsion factors (values ​​that represent interference between the propeller and the hull), and it is preferable to improve both values. Therefore, based on the test results shown in Figures 4(A) and 4(B), it is preferable to set the position of the front end 22 of the fin 21 in the range of 1.0 ≤ SS ≤ 1.5. More preferably, the position of the front end 22 of the fin 21 may be set in the range of 1.1 ≤ SS ≤ 1.4.

[0036] 5 is a diagram showing the wake distribution on the propeller plane when the propeller is not operating. In the figure, the thick circular line P indicates the propeller plane, the thin solid line Q indicates the wake distribution of a ship that does not have fins equivalent to the fins 21 of this embodiment, and the dotted line R indicates the wake distribution of this embodiment that does have fins 21.

[0037] As shown in the figure, the wake distribution indicated by the thin line Q is distributed so that the flow speed increases overall with increasing distance from the hull. The numbers 0.1 to 0.5 in the figure indicate the wake ratio, and as the number increases, the flow speed decreases.

[0038] On the other hand, in the vessel according to this embodiment having the fins 21, it can be seen that a region V (for example, the area filled in gray) where the flow velocity is slow can be formed within the propeller surface (thick line P), as shown by the dotted line R. This means that the vortex formed by the fins 21 is guided and collected by the propeller 15. Therefore, by arranging the fins 21, it is possible to intentionally generate vortices to expand the region where the flow velocity is slow, thereby stabilizing the flow of the water current, and the vortex can be collected by the propeller 15.

[0039] Here, Figure 6 is an analysis diagram of the water flowing along the side of the bossing, where (A) shows the case without fins and (B) shows the case with fins. As shown in the figure, when analyzing part of the water flowing along the side of bossing 12, it is found that when there are no fins, as shown in Figure 6(A), the water flows toward the water surface and cannot be collected by propeller 15.

[0040] On the other hand, when the fins 21 are provided as shown in FIG. 6(B), it can be seen that the water flow is disturbed by the fins 21 and is collected by the propeller 15.

[0041] Next, the difference in effect between a slender ship and a full ship regarding the fin device 2 according to the first embodiment will be explained. Here, Fig. 7 is a perspective view showing the hull structure of a full ship, which is a comparative example. Fig. 8 is a diagram showing the improvement rate of a ship equipped with the fin device according to the first embodiment. In Fig. 8, the white bars show the improvement rate for a slender ship, and the gray bars show the improvement rate for a full ship.

[0042] The comparative example, a full ship 101, is equipped with a bossing 112 protruding downward from the stern section 111 and a hull planar section 113 in which the sides of both chords are formed approximately parallel from the top to the bottom, and has a hull form with a box coefficient CB of 0.75 or greater than 0.8.

[0043] As shown in Figure 7, a full ship has a shape in which the width of the ship narrows from the hull flat section 113 to the rear of the stern section 111. In addition, in order to compare the improvement rate with this embodiment, the full ship has fins 121 arranged on both sides of the bossing 112.

[0044] Figure 8 shows the results of tank tests on a model of ship 1 (slender ship) shown in Figure 1 and a model of full ship 101 shown in Figure 6. The vertical axis of Figure 8 shows the improvement effect (%), with positive values ​​indicating an improvement effect and negative values ​​indicating no improvement effect. The horizontal axis shows the test items, which, from left to right, are effective horsepower, 1-t (thrust reduction coefficient), 1-wt (effective wake coefficient), and shaft horsepower.

[0045] In the item of effective horsepower, no improvement effect was observed for either Ship 1 (slender ship) or the full ship 101. In the item of 1-t (thrust reduction coefficient), an improvement effect was observed for both Ship 1 (slender ship) and the full ship 101, but the improvement effect was greater for Ship 1 (slender ship) than for the full ship 101.

[0046] In the 1-wt (effective wake coefficient) category, improvements were seen for both Ship 1 (slender ship) and Full Ship 101, but the improvement was greater for Ship 1 (slender ship) than for Full Ship 101. In the shaft horsepower category, improvements were seen for Ship 1 (slender ship), but no improvement was seen for Full Ship 101.

[0047] Shaft horsepower means the output (horsepower) of the power generated by the propeller that can actually be used as power, so ultimately, by comparing the shaft horsepower, it is possible to evaluate the effectiveness of the fin device 2. In other words, the fin device 2 according to the first embodiment described above can improve the propulsion efficiency of a slender ship and achieve energy savings.

[0048] Next, a boat 1 equipped with a fin device 2 according to a second embodiment of the present invention will be described with reference to Fig. 9. Fig. 9 is a perspective view showing a boat equipped with a fin device according to the second embodiment of the present invention. Note that the same components as those in the first embodiment described above are given the same reference numerals and redundant description will be omitted.

[0049] The vessel 1 according to the second embodiment shown in Fig. 9 is equipped with a first leading fin 31 and a second leading fin 32 that are arranged forward and above the fin 21. The second leading fin 32 is arranged rearward and above the first leading fin 31. The first leading fin 31 and the second leading fin 32 have a flat plate shape that protrudes substantially horizontally in the ship's width direction, and are configured not to protrude from the hull planar portion 13.

[0050] In this way, by configuring the fin device 2 to include leading fins (first leading fin 31 and / or second leading fin 32) that precede the fin 21, the slow flow zone (slow speed zone) that has stagnated at the bottom 14 of the stern section 11 can be disturbed by vortices generated by the leading fins, and the water flow that formed the slow speed zone can be concentrated and guided to the propeller.

[0051] By arranging the leading fins forward and above the fins 21 as in the vessel 1 according to the second embodiment, the effects of the fins 21 and the leading fins can be enjoyed without interference between them.

[0052] The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0053] 1 ship 2 Fin device 11 Stern 12 Bossing 13 Hull flat section 14 Bottom 15 propellers 16 Ship's Bottom 21 Finn 22 Front end 23 Rear end 24 Root part 25 Tip 31 First leading fin 32 Second leading fin 101 Enlarged ship 111 Stern 112 Bossing 113 Hull plane section 121 Finn

Claims

1. A fin device to be installed on a slender ship having a bossing protruding downward from a stern portion and a hull flat portion in which the ship's side surfaces on both chords are formed substantially parallel from the upper end to the lower end, a fin disposed on a side surface of the bossing; The front end of the fin is positioned in a range of square station equal to or greater than 1.0 and less than 1.5, The fin is disposed within a range from the front end to the rear end of the hull planar portion to a bilge height. A fin device characterized by:

2. The fin device of claim 1 , wherein the front end of the fin is located within a range of square stations 1.1 to 1.

4.

3. The fin device according to claim 1 , wherein the fin has a wing-shaped cross section and has an angle of attack such that the rear end is positioned higher than the front end.

4. A fin device as described in claim 1, wherein the fin is formed so that the width of the tip portion is shorter in the length direction of the ship than the width of the base portion connected to the hull.

5. 10. The fin device of claim 1, further comprising one or more leading fins disposed forward and above the fin.

6. The fin device according to claim 1 , wherein the slender vessel has a squareness factor of 0.75 or less or 0.8 or less.

7. A vessel comprising the fin device according to any one of claims 1 to 6.

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