JP2008024072A - Stern duct and vessel equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stern duct improving propulsion efficiency of a vessel by enhancing cost performance by constituting the stern duct to be easily executed in a conventionally existing stern duct and improving energy saving effects, and the vessel equipped with the stern duct. <P>SOLUTION: This stern duct 10 has a ring-shape (cylindrical shape), and is mounted in front of a propeller 2 of the vessel. In the stern duct 10, a knuckle part 12 having a prescribed angle is formed by mounting a ring 11 at a rear edge of the stern duct 10. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a stern duct attached to the front of a propeller of a ship and a ship to which the stern duct is attached.

  In recent years, from the viewpoint of environmental problems, prevention of global warming, prevention of air pollution, and the like have become the most important issues regardless of the field (see, for example, Non-Patent Document 1). Ships are also strongly required to improve energy efficiency and reduce greenhouse gas (carbon dioxide) emissions. In order to improve the energy efficiency of the ship, that is, the propulsion efficiency of the ship, the case where an apparatus called an energy saving propulsion device or an energy saving device is attached to the hull is increasing (for example, see Non-Patent Document 2). For example, in a ship such as a tanker or a bulk carrier, in order to improve propulsion efficiency, there has conventionally been a stern duct that is an energy saving propulsion device attached in front of a stern propeller.

  Such a stern duct improves the propulsion efficiency by the thrust generated in the duct itself by the suction action during the operation of the propeller and the improvement of the flow velocity distribution of the fluid flowing into the propeller surface. For these reasons, it is common for the duct to have a cross-sectional shape of an airfoil or streamline. That is, by making the cross-sectional shape of the duct into a shape having a curved surface inside the duct, it was possible to achieve higher lift and higher rectifying action.

  As such, “a ring-shaped nozzle having a substantially inverted triangular shape in side view is provided between the stern portion of the hull and the propeller, and the diameter of the nozzle rear end is 50 to 80% of the propeller diameter. There has been proposed a “ship” characterized in that the horizontal distance between the nozzle rear end surface and the propeller outer peripheral tip is 10 to 30% of the propeller diameter (see, for example, Patent Documents). 1). The nozzle (duct) provided in this ship has a wing shape in cross section.

  Further, “a ship with a stern duct having a hull, a propeller attached to the stern of the hull, and a duct attached to the front side of the propeller, wherein the axis of the duct is more than the axis of the propeller. A vessel with a stern duct, characterized in that it is raised upward by 0 to 25%, preferably 5 to 20% with respect to the diameter of the propeller, and the cross-sectional shape of the duct is convex on the inside thereof. Has been proposed (see, for example, Patent Document 2). This ship devised how to install the duct (the installation position and angle in the height direction) in order to improve the propulsion efficiency.

Japanese Utility Model Publication No. 3-17996 JP-A-9-175488 "Recent energy-saving propulsion device" TECHNO MARINE 2005.5 p40-p48 “Ship Energy Saving Device SILD” Sumitomo Heavy Industries Technical Report Vol. 44 no. 131 19966.8 p48

  The nozzles and ducts described in Patent Document 1 and Patent Document 2 contribute to a significant improvement in propulsion efficiency even if the shape and improvements of the nozzles and ducts remain in accordance with the current concept of the nozzles and ducts. It is clear from the results of the tank test that it does not. In addition, manufacturing such nozzles and ducts requires much effort, time and cost. Therefore, it is desirable to maintain production efficiency by preventing further increase in labor, time and cost.

  Furthermore, from the contents described in Non-Patent Document 1 and Non-Patent Document 2, it is considered that there is much room for improving the propulsion efficiency of the ship by improving the stern duct mounted in front of the propeller of the ship. Therefore, it is desirable to improve so as to improve the propulsion efficiency of the ship while maintaining the production efficiency of the stern duct. In other words, the stern duct must be improved in consideration of the energy consumption of the ship in terms of propulsion efficiency and the labor, time and cost in terms of production efficiency.

  The present invention was made in order to solve the above-described problems, and it is possible to easily construct a conventional wing-type stern duct, thereby improving cost performance and improving energy saving effect. The present invention provides a stern duct that improves the propulsion efficiency of a ship and a ship to which the stern duct is attached.

  A stern duct according to the present invention is a cylindrical stern duct that is attached to the front of a propeller of a ship, and is characterized in that a ring is attached to a rear edge of the stern duct to form a knuckle portion having a predetermined angle. Moreover, the ship which concerns on this invention attached the said stern duct.

  The stern duct according to the present invention is a cylindrical stern duct that is attached to the front of the propeller of the ship, and a ring is attached to the rear edge of the stern duct to form a knuckle portion having a predetermined angle. The pressure distribution can be improved. If the thrust of the stern duct is improved, the thrust acting on the ship can be increased and the propulsion efficiency of the ship can be improved. Further, since the ring can be attached to a stern duct as existing, the labor, time and cost required for manufacturing are almost the same as those of the conventional stern duct.

  Since the ship which concerns on this invention is characterized by having attached said stern duct, it has all the effects which the stern duct has. Moreover, since any stern duct can be attached by a simple operation, it is possible to provide a ship with a better propulsion performance at low cost.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a schematic view showing a state where a stern duct (duct-shaped energy saving propulsion device) 10 according to Embodiment 1 of the present invention is attached to the stern of a hull 1. Based on FIG. 1, the operation principle of the stern duct 10 according to Embodiment 1 of the present invention will be described in comparison with a conventional stern duct 100. 1A shows a state where the stern duct 10 is attached, and FIG. 1B shows a state where the stern duct 100 is attached.

  As shown in FIG. 1, the stern duct 10 and the stern duct 100 are attached to the stern of the hull 1 and in front of the propeller 2 (the bow side). Thus, by attaching the stern duct 10 and the stern duct 100, the lift (arrow C) obtained by the circulation (circulating water flow) of the fluid generated around the stern duct 10 and the stern duct 100 itself by the suction action of the propeller 2 Can be used as the thrust of the ship (arrow D).

  Further, by attaching the stern duct 10 and the stern duct 100, the flow of the fluid (arrow A) from the front of the hull 1 is rectified and then fed into the propeller 2 (arrow B), and the diffusion of the frictional wake is diffused. It can be prevented. In other words, the stern duct 10 and the stern duct 100 are configured such that the thrust obtained by using the circulating water flow generated around the stern duct 10 and the stern duct 100 by the suction action of the fluid during the operation of the propeller 2 and the front of the hull 1. The propulsion efficiency of the entire ship is improved by the wake gain that rectifies the flow of fluid from the vessel and brings it to the surface of the propeller 2.

  The major difference between the stern duct 10 and the stern duct 100 is that a ring 11 is attached to the rear edge of the stern duct 10. That is, the ring 11 is attached to the rear edge of the stern duct 10 to form the knuckle portion 12 having a predetermined angle (see FIG. 4B). As described above, when the knuckle portion 12 is formed at the rear edge of the stern duct 10, the pressure distribution generated around the stern duct 10 can be changed more than the pressure distribution generated around the stern duct 100. As will be described in detail later, the force (thrust) acting on the stern duct 10 can be increased.

  FIG. 2 is a three-dimensional view showing the overall shape of the stern duct 10. Based on FIG. 2, the shape of the stern duct 10 is demonstrated. As described above, the stern duct 10 is attached to the stern part of the ship and in front of the propeller of the ship (the bow side) in order to improve the propulsion efficiency of the ship. Further, the stern duct 10 has a ring shape (cylindrical) front shape, and the length of the cord line connecting the front edge and the rear edge is gradually shortened downward. FIG. 2 also shows the overall shape of the stern duct 100.

  As shown in FIG. 2, the stern duct 10 is provided with a ring 11, which is different from the stern duct 100 in this respect. That is, the stern duct 10 has a knuckle portion 12 formed by mounting the ring 11. The knuckle portion 12 greatly changes the pressure distribution generated around the stern duct 10. The thrust generated in the stern duct 10 is increased by a large change in the pressure distribution generated around the stern duct 10 (see FIG. 4B).

  FIG. 3 is a detailed explanatory view for explaining a mechanism of thrust generated in the stern duct. Based on FIG. 3, the mechanism of the force (thrust T) acting on the stern duct attached to the hull 1 will be described in detail. Here, the upper cross-sectional shape of the conventional stern duct 100 is shown, and the thrust generation mechanism will be described as an example. The conventional stern duct 100 will be described as an example, but the same applies to the thrust generation mechanism in the stern duct 10.

  FIG. 3 shows a cross-sectional shape W <b> 1 at a predetermined position of the stern duct 100 attached to the stern of the hull 1. Here, a case where the predetermined position of the cross-sectional shape W1 is a position corresponding to the upper side portion of the stern duct 100 is shown as an example. Due to the influence of the hull 1 located in front of the stern duct 100, a fluid having an angle of attack α flows into the cross-sectional shape W1 of the stern duct 100 from the traveling direction of the ship. The angle of attack α is an angle formed by the chord line C and the fluid flow. The chord line C is a straight line connecting the front edge and the rear edge of the stern duct 100.

  Thus, when a fluid having an angle of attack α flows into the stern duct 100, the cross-sectional shape W1 of the stern duct 100 has a lift (force acting perpendicular to the direction of fluid flow) L and drag (fluid). A force D that works in parallel with the direction of the flow. Then, when this lift L is projected in the traveling direction of the hull 1, this projection component acts as a thrust (arrow L ′). Further, when this drag D is projected in the traveling direction of the hull, this projection component acts as a resistance force (arrow D ').

  Therefore, the force (thrust T) acting on the stern duct 100 is obtained by subtracting the projection component (arrow D ') of the drag D from the projection component (arrow L') of the lift L. That is, if this thrust T can be increased, the propulsion efficiency of the ship will be improved. In order to increase the thrust T, it is effective to increase the lift L acting on the cross-sectional shape W1 of the stern duct 100 or decrease the drag D, as will be described with reference to FIG.

  Next, the pressure distribution generated around the stern duct will be described. FIG. 4 is a cross-sectional view showing cross-sectional shapes of the stern duct 10 and the stern duct 100 at predetermined positions. FIG. 5 also shows a contour map representing the pressure coefficient distribution around the stern duct 10 and the stern duct 100. Based on FIGS. 4 and 5, the features of the stern duct 10 will be described in comparison with the conventional stern duct 100.

  4A shows the cross-sectional shape W1 of the stern duct 100, and FIG. 4B shows the cross-sectional shape W2 of the stern duct 10. Here, a case where the predetermined positions of the cross-sectional shape W1 and the cross-sectional shape W2 are positions corresponding to the upper side portions of the stern duct 100 and the stern duct 10 is shown as an example. 5A shows a contour map of pressure around the stern duct 100, and FIG. 5B shows a contour map of pressure around the stern duct 10, respectively.

  In FIG. 5, the vertical axis represents the pressure coefficient distribution (Cp), and the horizontal axis represents predetermined portions of the cross-sectional shape W1 and the cross-sectional shape W2. Here, a case where the angle of attack is set to 8 ° will be described as an example. Also, the cross-sectional shape W1 of the stern duct 100 shown in FIG. 4A and the cross-sectional shape W1 of the stern duct 100 shown in FIG. 5A are shown upside down, and the stern duct 10 shown in FIG. The cross-sectional shape W2 of FIG. 5 and the cross-sectional shape W2 of the stern duct 10 shown in FIG. 5B are shown upside down.

  When the stern duct 100 is placed in the fluid flow, the back surface side (inner surface side of the stern duct 100) becomes low pressure, and the face surface side (outer surface of the stern duct 100) becomes high pressure. As shown in FIG. 5 (a), the interval between the contour lines on the back surface side is narrowed and the pressure coefficient is relatively negative (low pressure), and the interval between the contour lines on the face surface side is relatively small. It can also be seen from the fact that the pressure coefficient is relatively positive (high pressure) with increasing. That is, as shown in FIG. 4A, the pressure (P1H) on the face side is higher than the pressure (P1L) on the back side (P1H> P1L).

  Similarly, when the stern duct 10 is placed in the fluid flow, the back surface side (inner surface side of the stern duct 10) becomes low pressure, and the face surface side (outer surface of the stern duct 10) becomes high pressure. As shown in FIG. 5B, this is because the interval between the contour lines on the back surface side becomes narrower and the pressure coefficient is relatively negative (low pressure), and the interval between the contour lines on the face surface side. It can also be seen from the fact that the pressure coefficient is relatively positive (high pressure) with increasing. That is, as shown in FIG. 4B, the pressure on the face side (P2H) is higher than the pressure on the back side (P2L) (P2H> P2L).

  As described with reference to FIG. 3, the lift L acting on the stern duct 100 and the stern duct 10 depends on the magnitude of the difference between the pressure on the back surface side and the pressure on the face surface side in addition to the magnitude of the angle of attack α. There will be a difference in the size that occurs. That is, if the difference between the pressure on the Back surface side and the pressure on the Face surface side increases, the lift L also increases accordingly. Therefore, it is desirable that the stern duct has a cross-sectional shape in which the difference between the pressure on the back surface side and the pressure on the face surface side is large.

  The stern duct 10 according to the first embodiment is characterized in that a ring 11 is mounted on the rear edge. Then, as shown in FIG. 4B, the knuckle portion 12 is formed in the cross-sectional shape W2. In other words, the stern duct 10 forms the knuckle portion 12 by attaching the ring 11, and accordingly, the camber of the stern duct 10 increases, and the pressure on the back surface side and the face surface side of the stern duct 10 are increased. The difference from the pressure can be increased.

  5A and 5B, it can be seen that the pressure coefficient distribution of the stern duct 10 is larger than the pressure coefficient distribution of the stern duct 100 (P2H> P1H, P2L <P1L). ). That is, the difference between the pressure on the back surface side and the pressure on the face surface side of the stern duct 10 can be made larger than the difference between the pressure on the back surface side and the pressure on the face surface side of the stern duct 100. Therefore, the lift L of the stern duct 10 becomes larger than the lift L of the stern duct 100, and as a result, the thrust T of the stern duct 10 becomes larger than the thrust T of the stern duct 100.

  FIG. 6 is a pressure distribution diagram in which only the pressure coefficient distribution on the duct surfaces of the stern duct 100 and the stern duct 10 is extracted. Based on FIG. 6, it will be described that the pressure coefficient distribution on the duct surface of the stern duct 10 is larger than the pressure coefficient distribution on the duct surface of the stern duct 100. As shown in FIG. 5A and FIG. 5B, it was found that there was a pressure difference between the pressure on the back surface side and the pressure on the face surface side of the cross-sectional shapes W1 and W2.

  That is, as shown in FIG. 6, the pressure difference on the duct surface of the stern duct 10 is larger than the pressure difference on the duct surface of the stern duct 100. Therefore, as is clear from FIG. 6, the stern duct 10 can make the pressure difference larger than that of the stern duct 100, so that the thrust T of the ship to which they are attached can be further improved.

  FIG. 7 is an explanatory diagram showing the thrust reduction coefficient of the ship. Based on FIG. 7, the thrust reduction coefficient which is one element for estimating the horsepower of the ship will be described. Here, a low-speed enlarged ship without a stern duct ((a) shown in the figure), a low-speed enlarged ship with a conventional stern duct 100 ((b) shown in the figure), and a low-speed enlarged ship with a stern duct 10 attached The thrust reduction coefficient ((c) shown in the figure) is shown. In addition, the value shown here is measured based on the water tank test (CFD calculation (simulation calculation)) in the hull type water tank.

This thrust reduction coefficient is represented by (1-t). (T) is referred to as a thrust reduction rate, and is represented by ((T−R _T ) / T). Here, T is the thrust of the propeller (thrust), R _T represents the resistance of the ship in a towing state (Hull 1+ stern duct). That is, it means that the increase in ship resistance at the time of propeller operation is so large that (t) is large. Therefore, if the thrust reduction coefficient (1-t) is increased, an increase in ship resistance during propeller operation can be suppressed, and the propulsion efficiency of the ship is also improved. Increasing the thrust reduction constant (1-t) means decreasing (t).

  The three types of thrust reduction coefficients shown in FIG. 7 are compared, and the propulsion efficiency effect of the ship with the stern duct 10 attached will be described. Here, the case where the ring 11 having a length corresponding to 10% of the upper cord line length of the stern duct 10 is attached to the stern duct 10 will be described as an example. In FIG. 5, description will be made assuming that the thrust reduction coefficient of a ship without a stern duct attached is 1.000.

  Then, as a result of the water tank test, it was found that the thrust reduction coefficient of the ship with the conventional stern duct 100 attached was 1.010, and the thrust reduction coefficient of the ship with the stern duct 10 attached was 1.030. That is, when the stern duct 10 is installed, the thrust reduction coefficient is improved by about 3% compared to the case where the stern duct is not installed, and the thrust reduction coefficient is compared with the case where the conventional stern duct 100 is installed. That is an improvement of about 2%.

  If the thrust reduction coefficient is improved, the propulsion efficiency of the ship is improved as described above. That is, if the thrust reduction coefficient is improved by 2% in a low-speed enlargement ship, it will lead to a significant improvement in propulsion efficiency. For example, assuming that the stern duct 10 is attached to a large bulk carrier exceeding 200,000 tons as a low-speed enlargement ship, the fuel cost can be reduced by about 50,000 yen per day. And if the operation rate of this low speed enlargement ship is about 270 days a year, the fuel cost of 50,000 yen x 270 days = 13.5 million yen can be reduced.

  FIG. 8 is an explanatory diagram showing a simulation result of the thrust reduction coefficient (1-t) by CFD when the length of the ring 11 attached to the rear edge of the stern duct 10 is changed. In FIG. 8, the vertical axis represents the thrust reduction coefficient (1-t) as a ratio to the conventional stern duct 100, and the horizontal axis represents the ring length as a ratio to the upper cord line length of the stern duct. Yes. As shown in FIG. 8, if the length of the ring 11 is set in the range of 3% to 15% of the upper cord line length of the stern duct 10, the thrust reduction coefficient is improved by 1% or more than the conventional stern duct 100. I found out that

  In FIG. 7C, the thrust reduction coefficient of the ship to which the stern duct 10 having the ring 11 having a length corresponding to 10% of the upper cord line length of the stern duct 10 is attached is described as an example. As can be seen from the results, the thrust reduction coefficient can be improved by 1% or more when the length of the ring 11 is set around 10% of the upper cord line length of the stern duct 10, which is a significant improvement.

  As described above, the stern duct 10 according to the first embodiment can be easily constructed by a simple operation of attaching the ring 11 to the rear edge of the existing stern duct. It becomes possible to reduce the trouble and cost of remodeling. That is, the stern duct 10 has high cost performance. Therefore, the stern duct 10 can improve the energy saving effect and further improve the propulsion efficiency of the ship.

Embodiment 2. FIG.
FIG. 9 is an explanatory view showing a shape of the stern duct 10a according to Embodiment 2 of the present invention as viewed from the side. Based on FIG. 9, the stern duct 10a which concerns on Embodiment 2 of this invention is demonstrated. In the second embodiment, differences from the first embodiment will be mainly described, and the same parts as those in the first embodiment will be denoted by the same reference numerals and description thereof will be omitted.

  Although the stern duct 10 according to the first embodiment has been illustrated as an example in which the ring 11 corresponding to the entire periphery of the rear edge of the stern duct 10 is mounted, the stern duct 10a according to the second embodiment is in a predetermined position. A ring 11a that is cut horizontally and has a shape corresponding to the upper part of the rear edge of the stern duct 10a is mounted. That is, the thrust T generated in the stern duct 10a is greatly affected by the upper part of the rear edge of the stern duct 10a. Therefore, even if the ring 11a corresponding to the upper part of the rear edge is mounted, the same effect is recognized. .

  The predetermined position for cutting the ring 11a horizontally is not particularly limited. For example, it may be cut horizontally at the upper half position of the rear edge of the stern duct 10a, or may be further cut horizontally above. That is, the cutting position of the ring 11a may be determined in consideration of the magnitude of the thrust T that is desired to be generated in the stern duct 10a. Further, the ring 11a may be cut and attached to the stern duct 10a, or may be cut after being attached.

Embodiment 3.
FIG. 10 is an explanatory view showing a shape of the stern duct 10b according to Embodiment 3 of the present invention as viewed from the side. Based on FIG. 10, the stern duct 10b which concerns on Embodiment 3 of this invention is demonstrated. In the third embodiment, differences from the first and second embodiments will be mainly described, and the same parts as those in the first and second embodiments will be denoted by the same reference numerals and the description thereof will be omitted. It shall be.

  The stern duct 10 according to the first embodiment has been illustrated by way of example in which the side surface shape has a substantially inverted triangular shape (non-axisymmetric shape), but the stern duct 10b according to the third embodiment is An example is shown in which the lower part and the lower part have an axisymmetric shape formed with the same dimensions. That is, the shape of the stern duct 10b to which the ring 11b is mounted is not particularly limited, and the ring 11b may be formed in the same shape as the rear edge of the stern duct 10b. Therefore, it can be attached to a conventional stern duct 100 like a simple construction.

Embodiment 4 FIG.
FIG. 11 is an explanatory view showing a shape of the stern duct 10c and the stern duct 10d according to Embodiment 4 of the present invention as viewed from the side. Based on FIG. 11, the stern duct 10c and the stern duct 10d which concern on Embodiment 4 of this invention are demonstrated. In the fourth embodiment, differences from the first to third embodiments will be mainly described, and the same parts as those in the first to third embodiments will be denoted by the same reference numerals and the description thereof will be omitted. It shall be.

  Although the stern duct 10 to the stern duct 10b according to the first to third embodiments has been illustrated as an example in which the cross-sectional shape has a wing shape (streamline type), the stern duct according to the fourth embodiment. 10c and the stern duct 10d have shown as an example the case where the cross-sectional shape has shapes other than a wing | blade type (streamline type). That is, the shape of the stern duct 10c and the stern duct 10d to which the ring 11c and the ring 11d are attached is not particularly limited, and the ring 11c and the ring 11d may have the same shape as the trailing edge of the stern duct 10c and the stern duct 10d. It's good.

  In other words, the cross-sectional shapes of the stern duct 10c and the stern duct 10d to which the ring 11c and the ring 11d are attached are not particularly limited, and the ring 11c and the ring 11d are formed based on the shape of the rear edge of the stern duct 10c and the stern duct 10d. It only has to be manufactured. Therefore, the stern duct 100 and the stern duct having other shapes as in the related art can be attached by simple construction.

Embodiment 5. FIG.
FIG. 12 is an explanatory view showing a shape of the stern duct 10e according to Embodiment 5 of the present invention as viewed from the side. Based on FIG. 12, the stern duct 10e which concerns on Embodiment 5 of this invention is demonstrated. In the fifth embodiment, differences from the first to fourth embodiments will be mainly described, and the same parts as those in the first to fourth embodiments will be denoted by the same reference numerals and the description thereof will be omitted. It shall be.

  Although the stern duct 10 to the stern duct 10d according to the first to fourth embodiments has been illustrated as an example in which the rear edge has a continuous ring shape (tubular shape), The stern duct 10e is cut horizontally at a predetermined position, and the case where the stern duct 10e is not completely ring-shaped (tubular) is shown as an example. For example, the stern duct 10e corresponding to the shape of the ring 11a as shown in the second embodiment may be used. That is, the ring 11e may have the same shape as the rear edge of the stern duct 10e.

Embodiment 6 FIG.
FIG. 13 is an explanatory diagram showing a shape of the stern duct 10f according to the sixth embodiment of the present invention viewed from the side. A stern duct 10f according to Embodiment 6 of the present invention will be described with reference to FIG. In the sixth embodiment, differences from the first to fifth embodiments will be mainly described, and the same parts as those in the first to fifth embodiments will be denoted by the same reference numerals and the description thereof will be omitted. It shall be.

  The ring 11 to the ring 11e according to the first to fifth embodiments have been illustrated by taking an example in which the shape viewed from the side is a rectangle, but the ring 11f according to the sixth embodiment is from the side. The case where the seen shape is quadrilateral (substantially trapezoidal) other than rectangular is shown as an example. That is, the knuckle part 12 should just be formed in the rear edge of the stern duct 10f, and the shape of the ring 11f is not specifically limited.

  For example, the ring 11f and the ring 11f 'may be formed so as to have a substantially trapezoidal shape in which the lengths of the left and right sides are different as in the shape viewed from the side of the ring 11f and the ring 11f'. In this case, the upper and lower angles may be the same or different. Moreover, you may make it have trapezoid shape from which the length of one side of upper and lower sides differs like the shape seen from the side of ring 11f ". In addition, the shape seen from the side of the ring 11f to the ring 11f ″ shown in FIG. 11 does not have to have a strict trapezoidal shape.

  In the first to sixth embodiments, the shape of the stern duct and the shape of the ring attached to the stern duct have been described by way of example. However, the present invention is not limited to the case shown here. That is, the knuckle part 12 should just be formed with a stern duct and a ring, and the shape of a stern duct and a ring is not specifically limited. Further, any one of the stern duct and the ring described in the first to sixth embodiments may be combined. Furthermore, the length in the front-rear direction of the hull 1 of the rings 11 to 11 f ″ is not particularly limited. In any case, the ring shape may be determined in consideration of the thrust T generated in the stern duct, the shape of the stern duct, the labor and time required for manufacturing, time and cost. Therefore, it is possible to improve the propulsion efficiency while improving the production efficiency.

It is the schematic which shows the state which attached the stern duct which concerns on Embodiment 1. FIG. It is a three-dimensional view showing the overall shape of the stern duct. It is detailed explanatory drawing for demonstrating the mechanism of the thrust to generate | occur | produce. It is sectional drawing which shows the cross-sectional shape in the predetermined position of a stern duct. It is a contour map showing the pressure coefficient distribution around the stern duct. It is the pressure distribution figure which extracted only the pressure coefficient distribution on the duct surface of a stern duct. It is explanatory drawing which showed the thrust reduction coefficient of the ship. It is explanatory drawing which shows the result of the thrust reduction coefficient by CFD at the time of changing the length of a ring. It is explanatory drawing which shows the shape which looked at the stern duct which concerns on Embodiment 2 from the side. It is explanatory drawing which shows the shape which looked at the stern duct which concerns on Embodiment 3 from the side. It is explanatory drawing which shows the shape which looked at the stern duct which concerns on Embodiment 4 from the side. It is explanatory drawing which shows the shape which looked at the stern duct which concerns on Embodiment 5 from the side. It is explanatory drawing which shows the shape which looked at the stern duct which concerns on Embodiment 6 from the side.

Explanation of symbols

1 hull, 2 propeller, 10 stern duct, 10a stern duct, 10b stern duct, 10c stern duct, 10d stern duct, 10e stern duct, 10f stern duct, 11 ring, 11a ring, 11b ring, 11c ring, 11d ring, 11e Ring, 12 knuckle section, 100 stern duct.

Claims (6)

A cylindrical stern duct installed in front of the ship propeller,
A stern duct having a predetermined angle formed by attaching a ring to a rear edge of the stern duct. The stern duct according to claim 1, wherein the ring has a shape similar to a rear edge of the stern duct. The stern duct according to claim 1 or 2, wherein the shape of the ring as viewed from the side of the ship is a square shape. The stern duct according to claim 3, wherein the square shape is a substantially trapezoidal shape. The stern duct according to any one of claims 1 to 4, wherein the ring is formed by horizontally cutting at a predetermined position corresponding to an upper portion of a rear edge of the stern duct. A ship to which the stern duct according to any one of claims 1 to 5 is attached.

Images