stern pipe

Abstract

The present application provides a kind of ship tail pipeline.The ship tail pipeline (1) is the ship tail pipeline (1) with pipeline main body (11), the pipeline main body (11) is the single pipe being arranged in the stern pipe (9) periphery of the stern of the ship (100) in front of propeller (5) and axially towards the direction of ship length, to be configured in the position and posture that the pressure inside the surface of pipe is lower than the outside;The pipeline main body (11) is provided with notch (23), the notch (23) is formed along the circumferential direction of the pipe of pipeline main body (11) and is the long hole that the inner periphery of pipeline main body (11) is communicated with outer periphery, part of water flow flowing on the outside of pipeline main body (11) is introduced to the inside of pipeline main body (11);Therefore, the number of pipeline, the shape can not be greatly changed from the configuration of the past to increase the thrust, and the adjustment of the thrust becomes easy.

Description

Technical Field

[0001] This invention relates to stern ducts. Background Technology

[0002] A stern pipe is a tubular structure located at the stern of a ship, in front of the propeller. Stern pipes generally have the function of straightening the water flow generated during the ship's movement to reduce hull resistance, and also have the function of generating thrust using the water flow.

[0003] One method to generate thrust through the stern pipe is to make the pipe's cross-section airfoil-shaped to generate lift using water flow, or to use the longitudinal component of the lift as thrust. In this method, since the thrust increases with the lift, it is possible to consider a structure that increases lift.

[0004] As a structure to increase lift, there is a structure described in Patent Document 1 that makes the pipe into a double-layered pipe to increase the wing area. However, due to the increase in the number of parts, the pipe becomes heavier. In addition, since the number of components supporting the pipe also increases, the viscous drag of the parts where the components are located increases. Patent Document 1 also discloses a structure in which a portion of the inner pipe is offset forward of the outer pipe. However, since all the water flow along the outer periphery of the inner pipe is diverted to the outer pipe, it is difficult to adjust the flow rate of the water flow in the outer pipe, and there is also a possibility of water flow stripping at the rear end of the pipe, making thrust adjustment difficult.

[0005] As a structure to increase lift, there are also structures that change the shape of the wing without increasing the number of wings.

[0006] For example, in Patent Document 2, the pipe is made longitudinally so that only the flow along the two sides of the hull flows into the pipe, thereby efficiently generating thrust. However, since no other flow along the two sides is recovered as thrust, there is a problem of poor energy recovery efficiency. Patent Document 3 discloses a structure that increases thrust by installing a ring at the rear end of the pipe to control the pressure distribution. However, the pipe becomes heavier and the viscous drag increases accordingly with the amount of the ring, which also leads to a decrease in propulsion efficiency.

[0007] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2018-118699 Patent Document 2: Japanese Patent Application Publication No. 2018-79832 Patent document 3: Japanese Patent Application Publication No. 2008-24072. Summary of the Invention

[0008] The problem that the invention aims to solve If, like with traditional stern pipes, one tries to increase lift and thrust by changing the number and shape of the pipes, then in exchange for increased thrust, certain characteristics deteriorate. Therefore, there are limits to increasing thrust, and adjusting thrust is also more difficult.

[0009] The present invention was made in view of the above-mentioned problems, and the purpose is to provide a stern pipe that can increase thrust and make thrust adjustment easier without significantly changing the number and shape of the pipes from the conventional structure.

[0010] Methods used to solve problems The stern pipe of the present invention is a stern pipe having a pipe body, which is a single pipe located in front of the propeller of the ship, around the stern tube and axially oriented in the length direction of the ship, and is configured in such a position and orientation that the pressure on the inner side near the surface of the pipe is lower than that on the outer side. The pipe body is characterized by having a slot, which is an elongated hole formed along the circumference of the pipe body and connecting the inner and outer circumferences of the pipe body, so that a portion of the water flowing on the outer side of the pipe body is introduced into the inner side of the pipe body.

[0011] In this structure, water flowing on the outside with a pressure higher than that flowing inside the pipe is introduced from the slot into the inside of the pipe, which slows down the stripping of the water flow inside the pipe, increases lift, and thus increases the thrust brought by the stern pipe.

[0012] In this structure, since adding slots to the pipe increases thrust, thrust can be increased even without increasing the number of pipes, such as by making them double-layered. Furthermore, thrust can be increased without significantly altering the pipe's shape. Moreover, since the flow rate of water introduced into the main pipe body can be adjusted by changing the position and size of the slots, thrust adjustment is relatively easy.

[0013] Invention Effects According to the present invention, a stern pipe can be provided that can increase thrust and make thrust adjustment easier without significantly changing the number and shape of the pipes from the conventional structure. Attached Figure Description

[0014] Figure 1 This is a side view of the stern of a vessel equipped with the stern pipe of this embodiment.

[0015] Figure 2 (a) is Figure 1 Side view of the stern pipe. Figure 2 (b) is a diagram showing the direction of water flow on the inside and outside of the stern pipe.

[0016] Figure 3 yes Figure 1 A 3D view of the stern pipes.

[0017] Figure 4 (a) is Figure 1 A top view of the stern pipe. Figure 4 (b) is Figure 1 A bottom view of the stern pipe.

[0018] Figure 5 yes Figure 4 (a) is the AA section view of the main body of the pipe, which is also the axial section view containing the central axis of the main body of the pipe.

[0019] Figure 6 It means Figure 1 A side view of a modified example of the stern pipe. Detailed Implementation

[0020] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0021] Initially, refer to Figure 1 An overview of the stern pipe 1 in this embodiment will be described.

[0022] like Figure 1 As shown, the stern pipe 1 has a tubular pipe body 11. The pipe body 11 is a structure that, as the ship 100 sails, guides, straightens, and directs the wake flowing along the outer surface of the hull 3 into the propeller 5, thereby improving the propulsion efficiency of the hull 3. The pipe body 11 is also a structure that utilizes the water flow into it to generate thrust that propels the hull 3.

[0023] The main body of the pipe 11 is located forward of the propeller 5 at the stern of the ship 100 in the longitudinal direction, and is located around the stern tube 9, which is a watertight structure around the propeller shaft of the hull 3.

[0024] The main body of the pipe 11 is a single pipe oriented axially in the X direction towards the length of the ship. Figure 1The illustration shows a conical single pipe that expands in diameter towards the bow. Preferably, the inner side of the pipe body 11 is positioned within the wake, while the outer side is positioned within a flow with a faster velocity than the inner side. The reason for this configuration of the pipe body 11 is as follows: The water flow generated during the navigation of the ship 100 can be broadly divided into a wake flowing along the hull 3 and a uniform flow flowing further away from the hull 3 than the wake. Since the wake flows along the hull 3, it loses energy due to frictional resistance with the outer surface of the hull 3, resulting in a slower velocity and lower pressure compared to the uniform flow. Furthermore, the wake may form vortices due to the shape of the hull 3. On the other hand, at a distance further away from the hull 3 than the wake, since there is no frictional resistance with the hull 3, the velocity does not decrease, the pressure does not drop, and the direction of flow is not affected by the shape of the hull 3. Therefore, the further away from the hull 3, the more uniform or equivalent the water flow becomes, with a higher velocity and pressure compared to the wake. Thus, in order to rectify the wake and direct it into the propeller 5, it is preferable to position the main pipe 11 forward of the propeller 5 along its length and to position the inner side of the pipe within the wake.

[0025] Furthermore, the pipe body 11 is configured in a position and orientation that generates negative pressure inside the pipe. Specifically, it is configured in a position and orientation such that the pressure inside the pipe near the surface is lower than that on the outside. The reason for generating negative pressure is that it creates an effect that draws water into the interior of the pipe body 11, thereby generating thrust. The position and orientation for generating negative pressure are determined based on the flow of water from the hull 3 into the pipe body 11. Figure 1 As shown, when the pipe body 11 is conical in shape, in order to generate negative pressure, it is necessary to... Figure 1 As shown, the tilt angle α of the outer circumference of the cone relative to the X direction, which is the axial direction, is set to the angle that generates negative pressure inside the pipe. The tilt angle α is also called the attack angle. Furthermore, if the tilt angle α is given relative to the axial direction, the lift generated by the pipe body 11 being placed in the water flow is tilted relative to the vertical direction and has a component in the ship's length direction, so this component becomes the thrust that propels the hull 3.

[0026] In addition, Figure 1The pipe body 11 is illustrated with a conical shape, but the shape does not have to be conical as long as it can rectify the wake flow and generate thrust through the generation of negative pressure. For example, a cylinder can be used as a shape other than a cone. Furthermore, it could be a semi-cylindrical or semi-conical shape where the length of the arc of the cylinder or cone is half the circumference, the arc is the upper half of a circle when viewed from the ship's length, and the two ends of the arc are connected by a plate-like member. Alternatively, it could be a fan-shaped shape where the length of the arc of the cylinder or cone is less than half the circumference, the arc is part of the upper half of a circle when viewed from the ship's length, and the two ends of the arc are connected by an L-shaped member. In the following description, the case where the pipe body 11 is conical will be used as an example.

[0027] The above is a summary description of the stern pipe 1 of this embodiment.

[0028] Next, refer to Figures 2-6 The details of the construction of the stern pipe 1 in this embodiment are explained.

[0029] like Figures 2-4 As shown, the stern pipe 1 has a sleeve (boss) 14, vertical plates 15a and 15b, a pipe body 11, and a notch 47.

[0030] Figure 3 The sleeve 14 shown is a cylindrical component used to fix the stern pipe 1 to the periphery of the stern tube 9. The axis of the cylindrical tube is oriented in the X direction, which is the length of the ship, and it is disposed inside the pipe body 11 when viewed from the length of the ship. The inner diameter of the sleeve 14 is approximately the same as the outer diameter of the stern tube 9. It is inserted into the stern tube 9 and connected by known connection methods such as welding via connecting components such as a strut (not shown).

[0031] The outer diameter of the sleeve 14 needs to be such that it will not deform or be damaged by external forces such as water flow when the ship 100 is sailing. On the other hand, if the outer diameter of the sleeve 14 is too large, there is a possibility that it will obstruct the flow of water into the stern pipe 1, so an outer diameter that does not obstruct the flow is preferred.

[0032] The X-direction length of sleeve 14, which is the length in the ship's length direction, must also be at least long enough to not deform or be damaged under external forces such as water flow. The upper limit of the X-direction length is the length that does not interfere with the propeller 5 or the stern. Figure 3 The X-direction length of the sleeve 14 shown is less than the X-direction length of the pipe body 11.

[0033] Vertical plates 15a and 15b are plate-shaped components that connect the sleeve 14 to the pipe body 11. Figure 3The mid-plane direction is parallel to the X direction (which is the ship's length) and the Z direction (which is the vertical direction). The vertical plates 15a and 15b also serve to straighten the water flow into the inner side of the pipe body 11. For example... Figure 3 As shown, the upper end of the vertical plate 15a is connected to the uppermost end of the inner circumference of the pipe body 11, and the lower end is connected to the uppermost end of the outer circumference of the sleeve 14. The upper end of the vertical plate 15b is connected to the lowermost end of the outer circumference of the sleeve 14, and the lower end is connected to the lowermost end of the inner circumference of the pipe body 11. The vertical plates 15a, 15b and the sleeve 14 can be connected using known connection methods such as welding.

[0034] The thickness of vertical plates 15a and 15b, in Figure 3 The thickness of the vertical plates 15a and 15b in the Y direction, which is the width of the ship, must be such that they do not deform or get damaged under external forces such as water flow when the sleeve 14 is connected to the main body of the pipe 11. However, if the thickness of the vertical plates 15a and 15b in the Y direction is too thick, there is a possibility that it will obstruct the flow of water into the stern pipe 1. Therefore, the thickness that does not obstruct the flow is the upper limit.

[0035] The lengths of vertical plates 15a and 15b along the ship's length, in Figure 3 The length in the X-direction is preferably at least approximately the same as the length of the portion connecting to the sleeve 14 and the pipe body 11, and the vertical plates 15a and 15b. This is because maximizing the area of ​​the portion connecting to the sleeve 14 and the pipe body 11 results in the highest connection strength. The upper limit of the X-direction length is the length that does not interfere with the hull 3 and the propeller 5. Figure 3 The diagram shows a length approximately the same as that of the main pipe body 11.

[0036] The vertical lengths of the vertical plates 15a and 15b, in the direction of Figure 3 The length in the Z direction is appropriately set according to the installation position of sleeve 14. Figure 3 In the middle, since the sleeve 14 is offset downward from the center axis of the pipe body 11, the Z-direction length of the vertical plate 15a is longer than the Z-direction length of the vertical plate 15b.

[0037] As described in the summary of the stern pipe 1, the main pipe 11 is a component used for stream straightening, generating thrust from negative pressure, and generating thrust from lift.

[0038] like Figures 2-4 As shown, the side shape of the pipe body 11 varies with the central axis C of the pipe as the boundary. Specifically, as... Figure 2As shown in (a), the distance between the rear end 19a and the front end 31 in the length direction of the upper pipe body 11a, which is vertically above the central axis C, increases as it travels upwards in the X direction. On the other hand, since the rear end 19a in the length direction is vertically straight in side view, the front end 31 in the length direction becomes a shape that slopes obliquely upwards towards the bow. For example, in Figure 2 (a) illustrates the lengths L1-1 and L1-2 at two different vertical positions, with the length L1-2 of the upper part being longer than the length L1-1 of the lower part. On the other hand, the length L1-3 between the rear end 19a and the front end 31 of the lower pipe body 11b, which is located below the central axis C, is the same regardless of its vertical position, and its length is less than the length of the upper pipe body 11a. This is because, due to the direction of the accompanying flow, the thrust generated by the stern pipe 1 increases as it travels upwards, and decreases as it travels downwards. Therefore, traveling upwards increases the length of the pipe body 11 in the longitudinal direction, resulting in greater thrust.

[0039] like Figures 2-5 As shown, a slot 23, which serves as an elongated hole, is provided in the main body of the pipe 11.

[0040] Slot 23 Figure 2 (a) and Figure 3 As shown, it is formed circumferentially along the pipe body 11, such as Figure 5 As shown, it is an elongated hole that connects the inner and outer circumferences of the pipe body 11.

[0041] If slot 23 is set, then as follows Figure 2 As shown in (b), water flow A1, which is part of a uniform flow or a flow with a velocity equivalent to a uniform flow, is introduced into the inner side of the pipe body 11 through the slot 23, as part of water flows A1 and A2 flowing along the outer periphery of the pipe body 11. The water flow A1 introduced from the slot 23 has a higher pressure than the accompanying water flow B1 flowing into the inner side of the pipe body 11 from the longitudinal front end 31. Therefore, by introducing the higher-pressure water flow A1 into the inner side of the pipe body 11, energy is imparted to the water flow B1, thereby slowing down the shedding of the water flow B1 near the longitudinal rear end 19a of the inner side of the pipe body 11. As a result, the lift within the pipe body 11 increases, thus increasing the thrust.

[0042] Since the slot 23 is an elongated hole provided in the pipe body 11, it is not necessary to increase the number of pipe bodies 11 even if the slot 23 is provided. Furthermore, since the slot 23 is an elongated hole, it is not necessary to add new parts to the pipe body 11 to form the slot 23. Moreover, since the slot 23 is an elongated hole connecting the inner and outer circumferences of the pipe body 11, only a portion of the water flowing along the outer circumference of the pipe body 11 is introduced into the interior of the pipe body 11. Therefore, unlike the case where the pipe is made into a double-walled pipe, where all the water flowing along the outer circumference of the pipe body 11 is introduced into the interior of the pipe body 11, the flow rate of the water A1 introduced into the interior of the pipe body 11 can be adjusted by the position and size of the slot 23. Thus, it is easier to adjust the negative pressure and thrust within the pipe body 11 of the stern pipe 1.

[0043] The shape and size of the slot 23 can be appropriately set as long as it can guide a portion of the flow along the outer periphery of the pipe body 11 to the inner periphery, but it is preferred to set it to the following shape and size.

[0044] First, such as Figure 5 As shown, in the axial section including the central axis of the pipe body 11, the orientation of the slot 23 connecting the inner and outer circumferences of the pipe body 11 is preferably inclined at a predetermined angle β relative to the X direction, which is the axial direction of the pipe body 11. The angle β mentioned here refers to the upstream angle of the direction of water flow in the direction of the opening of the slot 23 from the inner circumferential opening end to the outer circumferential opening end, relative to the axial direction of the pipe body 11. More specifically, in Figure 5 In the axial section shown, the angle between the surface of the pipe body 11 tangent to the slot 23 and the central axis is the inclination angle β. The inclination angle β is preferably less than 90°. This is because if the inclination angle β exceeds 90°, the outer peripheral opening 23a of the pipe body 11 in the slot 23 faces the opposite direction to the direction of the water flowing on the outer peripheral side, making it difficult for water to flow into the slot 23 from the outside of the pipe body 11. Furthermore, when the inclination angle β is 90°, specifically when the slot 23 connects the inner and outer peripheries of the pipe body 11 radially, the outer peripheral opening 23a of the pipe body 11 in the slot 23 is orthogonal to the direction of the water flowing on the outer peripheral side, making it difficult for water to flow into the slot 23. Therefore, the inclination angle β is preferably 90° or less.

[0045] On the other hand, if the inclination angle β of the groove 23 relative to the axial direction of the pipe body 11 is set to Figure 1 If the inclination angle α of the conical outer periphery of the pipe body 11 shown is less than that, the groove 23 will have difficulty connecting the inner and outer peripheries of the pipe body 11. Therefore, the inclination angle β is preferably larger than the inclination angle α.

[0046] Furthermore, the tilt angle β is most preferably the same as the angle of attack γ of the inner circumference of the longitudinally inclined front end 31 of the pipe body 11 relative to the axial direction. The reason is as follows.

[0047] The inner circumference of the pipe body 11 is inclined at an angle such that it expands in the direction of the ship's length to increase lift. Therefore, a portion of the water flowing into the pipe body 11 from its longitudinal front end 31 collides with the inner circumference of the pipe body 11 and flows within the pipe body 11 at an angle of attack γ. Thus, by setting the inclination angle β of the slot 23 to be equal to the angle of attack γ, it is possible to... Figure 2 (b) shows that the water flow A1 flowing in from the outside of the pipe body 11 through the slot 23 and the water flow B1 flowing in from the longitudinal front end 31 of the pipe body 11 have the same orientation.

[0048] By aligning the directions of water flow A1 and water flow B1, the effect of slowing down the stripping of water flow B1 caused by water flow A1 near the longitudinal rear end 19a of the pipe body 11 is improved. Furthermore, the range of the longitudinal front end 31 described here is the range defined by the angle of attack γ.

[0049] As such Figure 5 The inclination angle β of the slot 23 shown is set to be equal to the angle of attack γ. Alternatively, a slot 23 with an inclination angle β can be formed in a conventional pipe without a slot 23. However, it is more preferable to make it into a slot 23 with an inclination angle β. Figure 5 The shape shown in (a).

[0050] Specifically, firstly, as Figure 5 As shown in (a), the axial section of the pipe body 11, including the central axis of the pipe, has an airfoil shape. This is to increase thrust in order to increase lift. In this shape, the axial section of the pipe body 11 is divided into a forward and backward shape along the slot 23 in the X direction, which is the ship's length direction. Here, the part located aft of the slot 23 in the ship's length direction is called the aft portion 19 of the pipe, and the part located forward of the slot 23 in the ship's length direction is called the forward portion 21 of the pipe.

[0051] The specific shape of the rear portion 19 of the pipe is preferably as follows. First, as... Figure 5 As shown in (b), in the axial cross-sectional shape of the pipe body 11, the shape surrounded by the closed curve is the overall shape 45. The closed curve is formed by connecting the outer periphery of the axial cross-section of the pipe body 11, except for the slot 23, in a loop shape. Figure 5 (a) The preferred axial cross-sectional shape of the rear portion 19 of the pipe shown is such that the radius of the chamfer of the rear end portion 19a in the longitudinal direction is the same as the radius of the chamfer of the rear end portion 19c in the longitudinal direction of the overall shape 45, and the shape other than the chamfer is such that... Figure 5(b) shows a scaled-down similar shape to the overall shape 45. The reason for setting the radius of the chamfer of the longitudinal rear end 19a to be the same as the radius of the chamfer of the longitudinal rear end 19c of the overall shape 45 is that if the longitudinal rear end 19a is simply scaled down in a similar shape, the longitudinal rear end 19a will become too thin and its strength will decrease.

[0052] Next, the preferred axial cross-sectional shape of the front portion 21 of the pipe is such that the inclination angle of the opposing portion 35, which is located across the slot 23 and faces the rear portion 19 of the pipe, is the same as the inclination angle of the front end 33 of the opposing portion of the rear portion 19 of the pipe relative to the axial direction, and the shape other than the opposing portion 35 is the same as the overall shape 45. This will be explained in more detail.

[0053] The rear portion 19 of the pipe has a similar shape to the overall shape 45 except for the radius of the chamfered portion of its rear end 19a in the longitudinal direction. Therefore, the front end 33 of the rear portion 19 in the axial direction has a similar shape to the front end 31 of the main body 11 in the longitudinal direction, and its inclination angle β1 is equal to the angle of attack γ of the front end 31 of the main body 11 in the longitudinal direction.

[0054] The inclination angle β2 of the opposing portion 35 in the front part 21, which is opposite the front end 33 of the rear part 19, is set to be equal to the inclination angle β1 of the front end 33, and therefore equal to the angle of attack γ. Since the front end 33 and the opposing portion 35 are tangent to the slot 23, their inclination angles β1 and β2 become the inclination angle β of the slot 23. Thus, in this shape, the inclination angle β of the slot 23 becomes equal to the angle of attack γ.

[0055] In this way, the pipe body 11 preferably has the rear part 19 of the pipe made into a shape similar to the overall shape 45, and the inclination angle β2 of the front part 21 of the pipe is matched with the inclination angle β1 of the front end 33 of the rear part 19 of the pipe, and the inclination angle β of the slot 23 is set as the angle of attack γ.

[0056] In this configuration, compared to the case where the slot 23 is simply formed with an angle of inclination β equal to the angle of attack γ of the forward end 31 of the wing along its length, the inlet and outlet of the slot 23 become smooth curved surfaces that match the shape of the wing. Therefore, it is difficult for water flow stripping and viscous drag to occur at the inlet and outlet of the slot 23, and the strength of the inlet and outlet can also be ensured.

[0057] Figure 5(a) The longer the width D in the axial section of the slot 23, specifically the shorter distance between the opposing surfaces of the rear portion 19 and the front portion 21 of the pipe in the axial section, the greater the flow rate of water that can be introduced into the inner side of the pipe body 11. However, if the flow rate is too high, the water flow will detach prematurely near the rear end 19a in the longitudinal direction inside the pipe body 11, forming vortices and hindering flow rectification, which is contrary to the effect of slowing down the detachment of the water flow as intended by the slot 23. Therefore, the width D is preferably set to a range where the water flow will not detach prematurely. Specifically, it is preferable to be 1% to 6% of the total longitudinal length of the pipe body 11 at the location where the slot 23 is provided, i.e., the chord length L1. Furthermore, if the width D is 2% to 4% of the chord length, the effect of slowing down the detachment of the water flow is improved, so it is more preferable.

[0058] If we only consider the length direction of slot 23... Figure 2 (b) As shown, water flow A1 is introduced into the inner side of the pipe body 11 through slot 23 and energy is imparted to water flow B1. It is preferable to position the slot 23 towards the front. On the other hand, if it is too far forward, the flow rate of the introduced water flow A1 will be too high, causing the water flow to separate prematurely near the rear end 19a in the longitudinal direction inside the pipe body 11, forming vortices and hindering flow rectification. This could contradict the purpose of providing slot 23—to slow down separation. Therefore, the longitudinal position is preferably set within a range where the water flow will not separate prematurely. Specifically, it is preferable to position the slot 23 at a distance of 20% to 80% of the chord length L1 from the front end 31 in the longitudinal direction of the pipe body 11 where slot 23 is located. Figure 5 If the ratio is L3 / L1, then the preferred ratio is 0.2 or higher and 0.8 or lower, or L3:L2 is 2:8 to 8:2.

[0059] Furthermore, the longitudinal position of slot 23 is specified as follows. First, as... Figure 5 As shown, in the axial section of the pipe body 11, a parallel line C2 parallel to the central axis of the pipe is drawn from the rear end 19a in the ship's length direction. Next, the intersection point 41 of the parallel line C2 with the front end 33 of the rear part 19 of the pipe and the intersection point 43 with the opposite part 35 of the front part 21 of the pipe are determined. The position P, which is equidistant from the intersection points 41 and 43 in the ship's length direction, is set as the ship's length direction position of the slot 23.

[0060] Furthermore, the preferred position of the slot 23 along the ship's length is a distance of 25% to 65% of the chord length L1 from the front end 31 of the main pipe body 11 along the ship's length at the location where the slot 23 is located. If in Figure 5The preferred ratio is L3:L2 of 2.5:7.5 to 6.5:3.5. This is because it further improves the effect of slowing down the stripping of the inner water flow near the rear end 19a of the pipe body 11 in the longitudinal direction. The most preferred position is at the location where the slot 23 is provided, at a distance of more than 30% and less than 50% of the chord length L1 from the front end 31 of the pipe body 11 in the longitudinal direction. Figure 5 If L3:L2 is represented as 3:7 to 5:5, then L2 is represented as 3:7 to 5:5.

[0061] in addition, Figure 2 (a) shows the main body of the pipe 11 Figure 5 The chord length L1 shown varies depending on the vertical position. Therefore, when the longitudinal position of the slot 23 is determined based on the chord length L1, there is a case where the longitudinal position of the slot 23 varies depending on the vertical position of the pipe body 11.

[0062] Specifically, Figure 2 (a) The upper part of the pipe body 11a, which is above the central axis C, has a shape that slopes upwards in the side view from the stern to the bow along the length of the ship. The length increases as it travels upwards. Therefore, when... Figure 5 When L3:L2 is set to a specific ratio, the slot 23 also appears in a side view as sloping upwards from the stern towards the bow. On the other hand, the lower pipe body 11b, located below the central axis C, has the same length in the ship's length direction regardless of its vertical position, so even when... Figure 5 When L3:L2 is set to a specific ratio, the slot 23 also becomes a vertical line in the side view.

[0063] Based on the length of the chord length L1 Figure 5 In the case of the width D of the groove 23 shown, the width D varies depending on the vertical position of the pipe body 11. For example, if a specific ratio is set for the width D to be between 1% and 6% of the chord length L1, the longer the chord length L1, the longer the width D becomes, and the shorter the chord length L1 becomes, the shorter the width D becomes. Therefore, Figure 2 (a) The width D of the slot 23 of the upper pipe body 11a increases as it moves upward. On the other hand, the width D of the slot 23 of the lower pipe body 11b is constant and is less than or equal to the width D of the slot 23 of the upper pipe body 11a.

[0064] Figure 5 The width D and tilt angle β of the slot 23 shown do not need to be constant within the slot 23. For example, in Figure 5In this design, the outer peripheral opening 23a and the inner peripheral opening 23b are enlarged to facilitate water flow in and out. However, if there are sections within the slot 23 with extremely different widths D and inclination angles β, the flow velocity and water pressure variations at these sections may affect the effect of slowing down the stripping near the rear end 19a of the water flow pipe body 11 in the longitudinal direction. Therefore, it is preferable that the difference between the width D and inclination angle β of the slot 23 is as small as possible within the slot 23.

[0065] in addition, Figure 1 The stern pipe 1 with slot 23 shown is positioned around the stern pipe 9 forward of the propeller 5 in the longitudinal direction, unlike the pipes of a ducted propeller which are positioned around the outer periphery of the propeller 5. The reason is as follows.

[0066] If the slot 23 is provided, the stripping of water flow inside the main pipe 11 near the rear end 19a in the longitudinal direction can be slowed down. On the other hand, since the flow rate of water flowing inside is greater than the amount of water flow A1 introduced, the more forward the slot 23 is positioned, the greater the turbulence of the flow caused by the formation of vortices when water stripping occurs near the rear end 19a in the longitudinal direction inside the main pipe 11. Therefore, when the stern pipe 1 is made into a ducted propeller, the turbulence of the flow flowing into the propeller 5 makes it easier for bubbles, called cavitation, to form compared to the case where the slot 23 is not provided. If cavitation occurs, there is a possibility of problems such as reduced thrust, damage to the propeller 5, noise, and vibration. However, especially if the thrust is reduced, the thrust-increasing effect of the slot 23 is offset by the thrust reduction caused by cavitation.

[0067] Therefore, the stern pipe 1 is not located around the outer periphery of the propeller 5 like the pipe of the ducted propeller.

[0068] exist Figures 1-5 In this configuration, the slots 23 are arranged around the entire circumference of the pipe body 11. Because the pipe body 11 is divided into a front section 21 and a rear section 19, as... Figure 3 As shown, the front part 21 and the rear part 19 of the pipe are connected to vertical plates 15a and 15b, respectively. Thus, the front part 21 and the rear part 19 of the pipe are connected to each other via vertical plates 15a and 15b.

[0069] However, slot 23 does not necessarily need to be set across the entire circumference. It can also be as follows: Figure 6As shown, the slot 23 is provided only in the upper part of the pipe body 11a, which is the upper half of the pipe body 11. More specifically, the slot 23 may also be provided only above the horizontal plane F passing through the central axis of the cone. The reason is as follows. Due to the direction of the wake flow, the thrust generated by the stern pipe 1 is greater as it travels upward and less as it travels downward. Figure 2 As shown in (a), the upward movement of the pipe body 11 increases its length along the ship's length, resulting in greater thrust. Therefore, the lower pipe body 11b is shorter in the ship's length direction compared to the upper pipe body 11a, making it difficult to generate sufficient thrust even with the slot 23. Figure 5 As the width D shown increases, it becomes difficult to introduce water flow from the outside. Furthermore, the shorter the length of the main body 11 along its length, the more immediately the water flow introduced from the outside will be diverted. Figure 2 As shown in (a), the water flows out from the longitudinal rear end 19a of the pipe body 11, thus the effect of slowing down the stripping of the inner water flow near the longitudinal rear end 19a of the pipe body 11 becomes weaker. Furthermore, since the slot 23 is an elongated hole, there are cases where reinforcement is needed to prevent a decrease in the strength of the portion where the slot 23 is provided. Therefore, it is also possible to... Figure 6 As shown, the slot 23 is provided only in the upper part of the pipe body 11a, which is the upper half of the pipe body 11.

[0070] By providing the slot 23 only in the upper pipe body 11a where the thrust is stronger, and not providing the slot 23 in the lower pipe body 11b where the thrust is weaker, the strength of the pipe body 11 can be ensured while increasing the thrust.

[0071] In cases where connecting the front portion 21 and the rear portion 19 of the pipe solely with vertical plates 15a and 15b would cause strength issues, the front portion 21 and the rear portion 19 can be connected at those locations for reinforcement. Specifically, this can be achieved by either leaving the corresponding location without a notch 23 and maintaining the original shape of the pipe body 11, or by connecting the front portion 21 and the rear portion 19 with a reinforcement other than the vertical plates 15a and 15b.

[0072] If the location where the slot 23 is not provided, or where the front part 21 and the rear part 19 of the pipe are connected by a reinforcement other than the vertical plates 15a and 15b, is the position furthest from the vertical plates 15a and 15b in the circumferential direction of the pipe body 11, then the reinforcement effect is the highest, and therefore it is preferred. Figure 2 In (a), since the vertical plates 15a and 15b are located at the upper and lower ends of the pipe body 11 in the vertical direction, the preferred connection position is the middle position, which is the furthest point from the upper and lower ends in the circumferential direction. Specifically, in Figure 2In the side view shown in (a), it is preferable to designate a position where the two sides overlapping the central axis C are connected. If the strength of such a connection using only vertical plates 15a and 15b is insufficient, a position connecting the front portion 21 of the pipe to the rear portion 19 of the pipe may also be provided. Furthermore, the longer the circumferential length of the connecting portion, the greater the strengthening effect; however, the shorter the circumferential length of the slot 23, the weaker the thrust-enhancing effect. Therefore, the circumferential length of the connecting portion is preferably as short as possible within a range that ensures the required strength.

[0073] Figure 3 and Figure 4 The notch 47 shown is the part where the stern is inserted when a portion of the longitudinal front end 31 of the pipe body 11 is secured by engaging with the stern of the hull 3. For example... Figure 3 and Figure 4 As shown, the notch 47 is a defect that corresponds to the shape of the stern end into which the pipe body 11 bites, and is formed at the front end 31 in the longitudinal direction at the stern part into the hull 3.

[0074] The above is a detailed description of the structure of the stern pipe 1 in this embodiment.

[0075] Thus, the stern pipe 1 of this embodiment has a slot 23, which guides a portion of the water flow outside the pipe body 11 from the slot 23 to the inside of the pipe body 11, thereby slowing down the stripping of the water flow flowing inside the pipe body 11 near the rear end 19a in the longitudinal direction, thereby increasing the lift and thrust of the pipe body 11.

[0076] In this structure, it is not necessary to increase the number of pipe bodies 11, nor is it necessary to add new parts to the pipe bodies 11. Furthermore, since only a portion of the water flowing outside the pipe body 11 is introduced into the interior of the pipe body 11, the flow rate of the water A1 introduced into the interior of the pipe body 11 can be adjusted by the position and size of the slot 23, and the thrust adjustment is relatively easy.

[0077] Therefore, the stern pipe 1 can increase thrust without significantly changing the number and shape of the main pipe body 11 from the previous structure, and the thrust adjustment is easier.

[0078] The present invention has been described above with reference to the embodiments, but the present invention is not limited to the embodiments. Those skilled in the art will naturally be able to conceive of various modifications and improvements within the scope of the technical concept of the present invention, and these are also included in the present invention.

[0079] For example, in the above embodiment, a structure is illustrated in which a slot 23 is provided at only one location in the longitudinal direction of the pipe body 11. However, as long as the stripping of water flow near the rear end 19a in the longitudinal direction inside the pipe body 11 can be slowed down, multiple slots 23 can also be provided in the longitudinal direction.

[0080] Explanation of reference numerals in the attached figures 1: Stern Pipeline 3: Hull 5: Propeller 9: Stern tube 11: Pipeline body 11a: Upper pipe body 11b: Lower pipe body 14: Sleeve 15a, 15b: Vertical plates 19: Rear of the pipe 19a, 19c: Aft end in the direction of captain 21: Front part of the pipeline 23: Groove 23a: Peripheral opening 23b: Inner peripheral opening 31: Forehead of the ship in the direction of the captain 33: Frontend 35: Opposite part 41, 43: Intersection 45: Overall shape 47: Gap 100: Ships.

Claims

1. A stern pipe comprising a pipe body, said pipe body being a single pipe disposed in front of the ship's propeller around the stern tube and axially oriented in the length direction of the ship, configured in a position and orientation such that the pressure on the inner side near the surface of the pipe is lower than that on the outer side, characterized in that, The aforementioned pipe body has a slot, which is an elongated hole formed along the circumference of the aforementioned pipe body to connect the inner and outer circumferences of the aforementioned pipe body, so that a portion of the water flowing on the outside of the aforementioned pipe body is guided into the inner side of the aforementioned pipe body. The aforementioned pipe body is a single conical pipe that is axially oriented in the direction of the ship's length and expands in the direction of the ship's bow. The inclination angle of the outer periphery of the cone is configured to generate negative pressure on the inside of the pipe. In the axial section containing the central axis of the aforementioned pipe body, the groove that connects the inner and outer circumferences of the aforementioned pipe body is inclined at a predetermined angle relative to the direction parallel to the aforementioned axial direction. The angle on the upstream side of the aforementioned tilt angle is larger than the tilt angle of the outer circumference of the aforementioned cone but less than 90°; The aforementioned axial section of the aforementioned pipe body has a wing shape; In the aforementioned axial section, the shape of the aforementioned axial section located behind the aforementioned slot in the ship's length direction, i.e. the rear part of the pipe, is as follows: the radius of the chamfer at the rear end in the ship's length direction is the same as the radius of the chamfer at the rear end in the ship's length direction of the overall shape, and the part outside the chamfer at the rear end in the ship's length direction is a similar shape that is a scaled-down version of the aforementioned overall shape. The overall shape is formed by connecting the outer periphery of the aforementioned axial section of the aforementioned pipe body, excluding the aforementioned slot. In the aforementioned axial section, the shape of the aforementioned axial section located in front of the aforementioned slot in the ship's length direction, i.e. the front part of the pipe, is as follows: the inclination angle of the opposing part that is opposite the front end of the aforementioned rear part of the pipe across the aforementioned slot is the same as the inclination angle of the front end of the aforementioned rear part of the pipe relative to the aforementioned axial direction, and the shape other than the aforementioned opposing part is the same as the aforementioned overall shape.

2. The stern pipe as described in claim 1, characterized in that, The width of the aforementioned slot in the axial section containing the central axis of the aforementioned pipe body is more than 1% and less than 6% of the total length of the aforementioned pipe body in the longitudinal direction, i.e., the chord length, at the location where the aforementioned slot is provided.

3. The stern pipe as described in claim 1, characterized in that, The width of the aforementioned slot in the axial section containing the central axis of the aforementioned pipe body is more than 2% and less than 4% of the total length of the aforementioned pipe body in the longitudinal direction, i.e., the chord length, at the location where the aforementioned slot is provided.

4. The stern pipe as described in claim 1, characterized in that, The position along the ship's length where the aforementioned slot is located is a position that is more than 20% and less than 80% of the total length (chord length) of the aforementioned pipe body along the ship's length, at the position where the aforementioned slot is located, from the front end of the aforementioned pipe body along the ship's length.

5. The stern pipe as described in claim 1, characterized in that, The position of the aforementioned slot along the ship's length is a position that is more than 25% and less than 65% of the total length (chord length) of the aforementioned pipe body along the ship's length, at the location where the aforementioned slot is located, from the front end of the aforementioned pipe body along the ship's length.

6. The stern pipe as described in claim 1, characterized in that, The position of the aforementioned slot along the ship's length is a position that is more than 30% and less than 50% of the total length (chord length) of the aforementioned pipe body along the ship's length, at the position where the aforementioned slot is located, from the front end of the aforementioned pipe body along the ship's length.

7. The stern pipe as described in any one of claims 1 to 6, characterized in that, The aforementioned pipe body has the aforementioned slot only above the horizontal plane passing through the aforementioned central axis.

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