Method for changing bulbous bow shape and bulbous bow shape

Abstract

The application provides a bulbous bow face type conversion method and a bulbous bow face type. The bulbous bow face type conversion method comprises the following steps: obtaining a three-dimensional curved surface of a bulbous bow, obtaining a line type of a bow column side projection contour line and shapes of a plurality of bow waterlines vertically and spaced apart according to the three-dimensional curved surface; adjusting the line type of the bow column side projection contour line and the shapes of the bow waterlines vertically and spaced apart; and connecting adjacent bow waterlines after adjustment by using a curved surface to obtain a new bow face type. The bulbous bow face type conversion method can realize the conversion of the bulbous bow face type, and can automatically convert the bulbous bow into a vertical invisible bulb bow, thereby reducing the workload of manual adjustment of the background technology, saving adjustment time, and making the face type smoother after adjustment.

Description

Technical Field

[0001] This application belongs to the field of shipbuilding design, and in particular relates to a method for transforming the bow shape of a bulbous ship and the bow shape itself. Background Technology

[0002] Currently, the design process for conventional liquefied gas carriers and other medium- and low-speed vessels involves selecting the bow type, typically either a bulbous bow or a vertical stealth bulbous bow. The existing method involves manually adjusting the positions of points on the bulbous bow's surface. However, this manual adjustment is time-consuming and labor-intensive, the adjusted bulbous bow surface is not smooth enough, and it cannot achieve automatic transformation from a bulbous bow to a vertical stealth bulbous bow, thus hindering further optimization of the new bow's surface. Summary of the Invention

[0003] One of the objectives of this application is to provide a method for transforming the bow shape of a bulbous ship, which can realize the automatic transformation from a bulbous bow shape to a vertical stealth bulbous bow shape.

[0004] One of the purposes of this application is to provide a bow profile with good drag reduction and seakeeping performance.

[0005] To achieve the above objectives, this application provides a method for transforming the bow shape of a bulbous ship, comprising the following steps:

[0006] Obtain the three-dimensional curved surface of the bulbous bow. Based on the three-dimensional curved surface, obtain the line shape of the side projection outline of the bowpost and the shape of the multiple bow waterlines distributed vertically. Adjust the line shape of the side projection outline of the bowpost and the shape of each bow waterline distributed vertically. Connect the adjusted adjacent bow waterlines with curved surfaces to obtain a new bow profile.

[0007] Optionally, the first pillar side projection outline is provided with at least two fixed points and a movable point located between the fixed points, and adjusting the first pillar side projection outline includes adjusting the longitudinal position of the movable point.

[0008] Optionally, the projection profile of the first pillar has a longitudinal concave part of the bulbous nose, and the most concave point of the longitudinal concave part of the bulbous nose is the moving point. The longitudinal moving distance of the most concave point on the projection profile of the first pillar is greater than the longitudinal moving distance of other moving points.

[0009] Optionally, the moving point that is closer to the concave point in the vertical direction has a greater longitudinal moving distance than the moving point that is farther from the concave point in the vertical direction.

[0010] Optionally, the bow waterline has a waterline start point and a waterline end point. The waterline start point is located at or near the aforementioned section at 6% Lpp from the foremost point of the vessel, and the waterline end point is located at or near the projected outline of the bowpost. Adjusting the shape of the bow waterline includes adjusting the longitudinal position of the waterline end point.

[0011] Optionally, adjusting the shape of the bow waterline includes adjusting the tangent angle at the end of the waterline, where the tangent angle is the angle between the tangent at the end of the waterline and the centerline of the hull.

[0012] Optionally, adjusting the shape of the bow waterline includes adjusting the fullness of the bow waterline.

[0013] Optionally, the bow waterline includes the hull design waterline, wherein the change in the tangent angle at the end of the hull design waterline is greater than the change in the tangent angle at the end of the other bow waterlines; and / or the change in the fullness of the bow waterline of the hull design waterline is greater than the change in the fullness of the other bow waterlines.

[0014] Optionally, the change in the tangent angle at the end of the bow waterline, which is closer to the hull design waterline, is greater than that of the bow waterline, which is farther from the hull design waterline, and / or the change in the fullness of the bow waterline, which is closer to the hull design waterline, is greater than that of the bow waterline, which is farther from the hull design waterline.

[0015] This application also provides a bow shape, which is manufactured using the above-described bulbous bow shape transformation method.

[0016] This application has at least the following beneficial effects:

[0017] By adopting the above-mentioned bulbous bow face shape transformation method, it is possible to realize the face shape transformation of bulbous bow, and it can also automatically transform from bulbous bow to vertical stealth bulbous bow, reducing the workload of manual adjustment of background technology, saving adjustment time, and making the face shape smoother after adjustment. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the bulbous bow structure according to an embodiment of this application;

[0020] Figure 2 According to Figure 1 A schematic diagram illustrating the adjustment process of the side projection outline of the bulbous bow;

[0021] Figure 3 A schematic diagram of the side projection outline of the bow pillar of a bulbous bow under different parameters L;

[0022] Figure 4A schematic diagram of waterline reconstruction at the same height after the moving point P6 on the side projection outline of the first column is moved to P6';

[0023] Figure 5 This is a schematic diagram showing the distribution of changes in the tangent angle at the end of the waterline and the changes in the waterline fullness at the bow as a function of the ship's vertical height.

[0024] Figure 6 The bow waterline shape at the same design waterline height is shown under different variations in the tangent angle 'a' at the waterline endpoint and the variation in bow waterline fullness 'f'.

[0025] Figure 7 The shape of one of the waterlines L6' of the vertical stealth spherical head is shown;

[0026] Figure 8 The shape of multiple waterlines distributed vertically at intervals in this vertical stealth spherical head.

[0027] Illustration:

[0028] 1. Bow deck plane; 2. Side projection outline of the bow pillar of the bulbous bow type; 3. Side projection outline of the bow pillar of the vertical stealth bulbous bow type; 4. Section of the bow at 6% Lpp distance from the foremost point of the ship; 5. Section of the bow at 6% Lpp distance from the foremost point of the ship; 6. Bottom edge line of the ship. Detailed Implementation

[0029] The following specific embodiments illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this application can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, unless otherwise specified, the following embodiments and features in the embodiments can be combined with each other.

[0030] In the description of this application, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "longitudinal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0031] Reference Figures 1 to 8 The length direction of the ship is longitudinal, and the vertical direction of the ship is vertical.

[0032] This embodiment provides a method for transforming the surface shape of a bulbous bow, including the following steps:

[0033] Obtain the three-dimensional curved surface of the bulbous bow. Based on the three-dimensional curved surface, obtain the line shape of the side projection outline of the bowpost and the shape of the multiple bow waterlines distributed vertically. Adjust the line shape of the side projection outline of the bowpost and the shape of each bow waterline distributed vertically. Connect the adjusted adjacent bow waterlines with curved surfaces to obtain a new bow profile.

[0034] The bulbous bow profile transformation method described above can achieve profile transformation of bulbous bows, and can also automatically transform from a bulbous bow to a vertical stealth bulbous bow. This reduces the workload of manual background adjustments, saves adjustment time, and results in a smoother profile after adjustment.

[0035] Reference Figure 1 The bow is separated from the rest of the hull by the 6% Lpp section at the foremost point, where Lpp is the horizontal length between the bow and stern perpendiculars. The three-dimensional surface of the bow allows us to obtain the projected outline of the bowpost and multiple vertically spaced bow waterlines (see reference). Figure 2 ,L1-L11), where the solid line is the side projection outline of the bow of the bulbous bow, and the dashed line is the side projection outline of the bow of the vertical stealth bulbous bow.

[0036] The side projection outline of the forepost can be obtained by creating a cross-section along the ship's length. The side projection outline of the forepost can be divided into several line segments by multiple vertically spaced waterlines at the bow. The endpoints of each line segment serve as moving or fixed points for adjusting the side projection outline of the forepost. By keeping the fixed point stationary and adjusting the moving point longitudinally, the new side projection outline of the forepost can be obtained by connecting these points sequentially. The fixed points can be the highest and lowest points of the side projection outline of the forepost, or the intersections of the highest and lowest vertical waterlines with the side projection outline of the forepost, as shown in the reference. Figure 1 In one example, the fixed points are P1 and P12; in another example, the fixed points can be P1, P11, and P12, where P11 and P12 are straight lines. The moving points include the intersections of multiple waterlines and the projected outline of the bow side, which can be located between the fixed points, and the most concave point of the projected outline of the bow side along the ship's length, as shown in the reference. Figure 1 The moving points include P2 to P10, with the most concave point being P7. To ensure the smoothness of the new first pillar side projection outline, there should be no fewer than 10 water lines. The number of water lines should be such that manual calculation is convenient or does not affect the efficiency of computer operation. The water lines can be evenly spaced or distributed according to the curvature of the first pillar side projection outline.

[0037] During the movement, P1 and P12 can remain stationary while P2 moves to P11. When moving, the point with the greatest concavity, P7, moves the longest distance. The remaining points move according to their vertical distance from P7; points closer to P7 move the longest.

[0038] In the first embodiment, the longitudinal coordinate value of the concave point P7 is defined as P1x-L, where P1x is the longitudinal coordinate value of the foremost point of the ship. Since P1 is fixed, P1x is a constant. The parameter L is a variable. The longitudinal coordinate value of the moving point PN other than the concave point P7 is defined as PNx. After moving, the moving point PN becomes the moving point PN'. The longitudinal coordinate value of the moving point PN' is defined as PNx+(P1x-PNx) / L0*(L0-L), where L0 is the original depth of the bulbous nose concavity, that is, the longitudinal distance of the concave point P7 relative to the top of the bulbous nose.

[0039] By adjusting parameter L, the depth of the longitudinal concave part of the bulbous bow can be controlled. During the process of adjusting the longitudinal concave part of the bulbous bow, the longitudinal coordinate values ​​of other moving points PN' are also adjusted, which can obtain a side projection outline of the bow pillar that varies according to parameter L. This enables the transformation from the side projection outline of the bow pillar of a bulbous bow to the side projection outline of the bow pillar of a vertical stealth bulbous bow.

[0040] like Figure 2 As shown, when parameter L decreases, the projected outline of the first pillar changes from... Figure 2 (a) Transition to Figure 2 (b) When parameter L is 0, the side projection outline of the bow is the same as the side projection outline of the bow of a vertical, stealthy bulbous bow, i.e. Figure 2 (c). Reference Figure 3 The figure shows the variation of the projected profile of the bow for different parameters L. When parameter L = 0, the corresponding bow is a vertical stealth bulbous bow; when parameter L > 0, the corresponding bow is a bulbous bow.

[0041] In the second embodiment, before the movement, the longitudinal coordinate of the moving point PN is PNx, and N is 2, ..., 11. The longitudinal coordinate of the foremost point of the ship is P0x, and P1 can also be the foremost point of the ship, i.e., P1x = P0x.

[0042] After the movement, the moving point PN moves to the moving point PN'. The longitudinal coordinate of the most concave point P7 is P7x, and the longitudinal coordinate of the most concave point P7' is P7x+(L0-L). The movement distance is L0-L, where L is a variable. The longitudinal coordinate of the moving point PN other than the most concave point P7 is PNx. After the movement, the longitudinal coordinate of the moving point PN' is PNx+(P0x-PNx) / L0*(L0-L), and the movement distance is (P0x-PNx) / L0*(L0-L). Here, L0 is the longitudinal distance of the most concave point P7 relative to the top of the bulbous bow. When the top of the bulbous bow is aligned with the foremost point of the ship, L0 = P0x-P7x.

[0043] Based on the above calculation formula, it can be found that when the moving distance is less than P0x-P7x, the bow is a bulbous bow type. Figure 2 (a) and (b). When the moving distance is equal to P0x - P7x, the most concave point P7 is flush with the foremost point of the ship, and the bow is a vertical, stealthy bulbous shape, as shown in reference. Figure 2 (c). The depth of the bulbous nose can be optimized by adjusting the variable L.

[0044] In one example, the moving point P6 is the moving point that is closest to the concave point P7 vertically upwards, and the projection contour of the first column side where the moving point P6 and the concave point P7 are located is a straight line. In order to ensure that this straight line does not change except for moving a certain distance along the longitudinal direction, the moving distance of P6 is required to be equal to the moving distance of the concave point P7, which is L0-L.

[0045] The bow waterline has a waterline start point and a waterline end point. The waterline start point is located at or near the section 6% Lpp from the foremost point of the ship, and the waterline end point is located at or near the projected outline of the bowpost.

[0046] A new bow waterline is obtained by adjusting the longitudinal movement of points on the bow waterline, excluding the waterline termination point. The longitudinal movement distance of the waterline termination point is equal to the longitudinal movement distance of points on the projected outline of the bowpost at the same height.

[0047] A tangent is drawn to the endpoint of the waterline, forming a tangent angle with the ship's centerline. The endpoints of multiple vertically spaced bow waterlines have different tangent angles. The tangent angles of the endpoints of the highest and lowest vertically spaced bow waterlines are kept constant, while the tangent angles of the endpoints of the other bow waterlines are adjusted. The bow waterline includes the hull design waterline, i.e., the waterline at the ship's design draft. The change in the tangent angle at the endpoint of the hull design waterline is greater than the change in the tangent angles of the endpoints of the other bow waterlines. The change in the tangent angles of the endpoints of the other bow waterlines is adjusted according to their vertical distance from the hull design waterline; the change in the tangent angle of the endpoints of the bow waterlines closer to the hull design waterline is greater than that of the bow waterlines farther from the hull design waterline.

[0048] Reference Figure 5 The side projection outline of the first pillar intersects with each waterline at different points (from top to bottom, P1 to P11, some intersections are not shown). These intersections are the moving points or fixed points mentioned above. Figure 5 The right side shows the variation of the tangent angle at each end point of the waterline at the same height as the waterline. For example, the variation of the tangent angle at the end points of the waterline corresponding to points P3 and P6 is Δ3α and Δ6α, respectively. The variation of the tangent angle at the end point of the waterline corresponding to the design waterline is α, where α > Δ6α > 3α. The maximum variation of the tangent angle at the end point of the waterline is controlled by adjusting α, and the variation of the tangent angle at the end point of the waterline at different heights in the vertical direction of the hull is controlled by adjusting the distribution curve of the variation of the tangent angle along the vertical height of the hull.

[0049] The bow waterline fullness characterizes the shape of the bow waterline. Bow waterline fullness refers to the ratio of the closed area formed by the bow waterline on one side of the hull centerline, the hull centerline, and the aforementioned 6% Lpp section at the foremost point of the ship, to the smallest rectangle formed by the hull centerline and the aforementioned 6% Lpp section at the foremost point of the ship surrounding this closed area. (Refer to...) Figure 4 Before the movement, the fullness of the bow waterline where P6 is located is the ratio of the shaded area within rectangle OABP6 to the area of ​​the rectangle. After the movement, the fullness of the bow waterline where P6' is located is the ratio of the shaded area within rectangle OCDP6' to the area of ​​the rectangle.

[0050] Similar to the tangent angle at the end of the waterline, there is a corresponding bow waterline fullness at the same height. The variation in bow waterline fullness at the hull design waterline is greater than the variation in fullness of the other bow waterlines. The variation in fullness of the other bow waterlines is adjusted according to their vertical distance from the hull design waterline; the bow waterline with a closer vertical distance from the hull design waterline has a greater variation in fullness than the bow waterline with a greater vertical distance.

[0051] Reference Figure 5 The right side shows the variation in bow waterline fullness at the same height as the waterline. For example, the variation in bow waterline fullness at points P3 and P6 is Δ3f and Δ6f, respectively, while the variation in bow waterline fullness at the design waterline is f, where f > Δ6f > 3f. The maximum variation in bow waterline fullness is controlled by adjusting f, and the variation in bow waterline fullness at different heights along the vertical height of the hull is controlled by adjusting the bow waterline fullness distribution curve along the hull.

[0052] Therefore, the transformed bow waterline can be re-established using the waterline's starting endpoint, the tangent angle at the starting endpoint, the position and tangent angle at the ending endpoint, and the bow waterline fullness. In other words, after the new bowhead side projection outline is formed, adjusting the waterline's ending endpoint tangent angle change along the hull's vertical height distribution curve and the bow waterline fullness along the hull's vertical height distribution curve can optimize and obtain the new bow waterline. Figure 6 This shows the shape of the bow waterline at the same height as the design waterline under different variations in the tangent angle 'a' at the waterline endpoints and the variation in the bow waterline fullness 'f'.

[0053] By connecting the waterline at different heights of the bow with curved surfaces, a new bulbous bow shape is formed.

[0054] This application provides a bow section, manufactured using the aforementioned bulbous bow section transformation method. (Refer to...) Figure 7 The bow profile of this ship is a vertical stealth bulbous bow (L=0 in the above bulbous bow profile transformation method), with one of the waterlines L6' being the shape of (f=-0.15, a=10 in the above bulbous bow profile transformation method). This waterline L6' is long and slender, and the inlet section remains slender within a 2.5% Lpp length range from the bowpost. Figure 8 This refers to the vertically spaced waterline shape of the vertically stealthy bulbous bow. This design allows for a more uniform pressure distribution in the waterline intake area, reducing the initial wave height and minimizing ship drag. Furthermore, the relatively small variation in the waterline shape (between P6 and P7 in this example) results in a smaller increase in power during waves, improving wind and wave resistance. The increased longitudinal cross-sectional area also enhances maneuverability.

[0055] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of this application, and these improvements and substitutions should also be considered within the scope of protection of this application.

Claims

1. A method for transforming the bow profile of a bulbous ship, characterized in that, Includes the following steps: Obtain the three-dimensional curved surface of the bulbous bow. Based on the three-dimensional curved surface, obtain the line shape of the side projection outline of the bowpost and the shape of the multiple bow waterlines distributed vertically. Adjust the line shape of the side projection outline of the bowpost and the shape of each bow waterline distributed vertically. Connect the adjusted adjacent bow waterlines with curved surfaces to obtain a new bow profile. The first pillar side projection outline has at least two fixed points and a moving point located between the fixed points. Adjusting the first pillar side projection outline includes adjusting the longitudinal position of the moving point.

2. The bulbous bow shape transformation method according to claim 1, characterized in that, The first pillar side projection contour has a longitudinal concave part of the bulbous nose. The most concave point of the longitudinal concave part of the bulbous nose is the moving point. The longitudinal moving distance of the most concave point on the first pillar side projection contour is greater than the longitudinal moving distance of other moving points.

3. The bulbous bow shape transformation method according to claim 2, characterized in that, A moving point that is closer to the concave point in the vertical direction moves a greater distance vertically than a moving point that is farther from the concave point in the vertical direction.

4. The bulbous bow shape transformation method according to claim 1, characterized in that, The bow waterline has a waterline start point and a waterline end point. The waterline start point is located at or near the section 6% Lpp from the foremost point of the ship, and the waterline end point is located at or near the projected outline of the bowpost. Adjusting the shape of the bow waterline includes adjusting the longitudinal position of the waterline end point.

5. The bulbous bow shape transformation method according to claim 4, characterized in that, Adjusting the shape of the bow waterline includes adjusting the tangent angle at the end of the waterline, which is the angle between the tangent at the end of the waterline and the centerline of the hull.

6. The bulbous bow shape transformation method according to claim 4, characterized in that, Adjusting the shape of the bow waterline includes adjusting its fullness.

7. The bulbous bow shape transformation method according to claim 5 or 6, characterized in that, The bow waterline includes the hull design waterline, where the change in the tangent angle at the endpoint of the hull design waterline is greater than the change in the tangent angle at the endpoints of the other bow waterlines; and / or the change in the fullness of the bow waterline of the hull design waterline is greater than the change in the fullness of the other bow waterlines.

8. The bulbous bow shape transformation method according to claim 7, characterized in that, The change in the tangent angle at the end point of the bow waterline, which is closer to the design waterline of the hull, is greater than that of the bow waterline, which is farther from the design waterline of the hull, and / or the change in the fullness of the bow waterline, which is closer to the design waterline of the hull, is greater than that of the bow waterline, which is farther from the design waterline of the hull.

9. A bow profile, characterized in that, It is manufactured using the bulbous bow face transformation method according to any one of claims 1 to 8.

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