Installation method of large LNG ship bilge keel and large LNG ship bilge keel

Abstract

The invention discloses an installation method of a large LNG ship bilge keel and the large LNG ship bilge keel. The installation method sequentially comprises the steps that a streamline test is conducted on a large LNG ship to obtain a plurality of streamlines; selecting a streamline closest to the center of the bilge in each section as a mounting position of a sectional bilge keel in the section; and installing the subsection bilge keel in each subsection according to the determined streamline. The large LNG ship bilge keel comprises subsection bilge keels distributed on an outer plate of a ship body subsection, the installation position of the subsection bilge keel in each subsection is a streamline closest to the center of a bilge part in the ship body subsection, and the streamline is obtained by conducting a streamline test on a large LNG ship. The accuracy of the installation position of the ship bilge keel in each subsection is guaranteed, the stabilization effect and resistance of the ship bilge keel on the whole large LNG ship are balanced, the ship building efficiency is improved, structural stress concentration of the subsection bilge keel is reduced, and the service life of the large LNG ship bilge keel is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of wetland ecological restoration, and in particular to an installation method of a large-scale LNG ship bilge keel and the large-scale LNG ship bilge keel. Background Art

[0002] The bilge keel is a crucial feature of ship structure, typically installed along the bilge of the hull and extending along the length of the ship. It is used to reduce the ship's roll during navigation and improve its stability. Conventional ships can simulate the ship's streamline distribution through streamline testing during hydrodynamic analysis. These streamline tests only yield a single streamline, which serves as the installation location for the bilge keel. However, large LNG carriers with a capacity exceeding 200,000 cubic meters can obtain multiple streamlines through streamline testing. The bilge keel's installation location can only be determined by staff selecting one streamline based on experience. This not only reduces the bilge keel's roll reduction effect but also increases its resistance. Summary of the Invention

[0003] In response to the defects in the existing technology, the present application provides a method for installing the bilge keel of a large LNG ship and a large LNG ship bilge keel to solve the technical problems such as poor anti-rolling effect and large bilge keel resistance caused by the installation position of the bilge keel of a large LNG ship in the existing technology.

[0004] In order to achieve the purpose of the above invention, the technical solution provided by the present invention is as follows:

[0005] A method for installing a bilge keel of a large LNG ship comprises the following steps:

[0006] S1. Conduct streamline tests on large LNG carriers and obtain multiple streamlines on the outer plate of the hull;

[0007] S2. Divide the hull into multiple sections according to the hull's section dividing lines, and select the streamline closest to the bilge center in each section as the installation position of the section bilge keel in that section, wherein the streamline selected in each section is closer to the hull centerline toward the bow side than toward the stern side;

[0008] S3. Install segmented bilge keels in each segment according to the streamline determined in S2, with a certain distance between the segmented bilge keels.

[0009] In one embodiment, the segmented bilge keel includes a web, one end of which is fixed to the outer plate of the hull, and an angle between the web and the bottom plate of the hull is 40°-50°.

[0010] In one embodiment, the segmented bilge keel further comprises a face plate fixed to an end of the web away from the outer plate, and the face plate is perpendicular to the web.

[0011] In one embodiment, the web and the outer plate are fixedly connected by welding, a pad is provided between the web and the outer plate, the web is welded to the pad, and the pad is welded to the outer plate.

[0012] In one embodiment, the ends of the segmented bilge keels are fixed with a backing plate and a web by full penetration welding, the length of the full penetration welding of the backing plate is 200 mm, and the length of the full penetration welding of the web is 100 mm.

[0013] In one embodiment, the lengths of the web and the pad in the bow and stern directions are both longer than the length of the panel, and the length of the pad in the bow and stern directions is longer than the length of the web.

[0014] In one embodiment, the length of the base plate in the bow and stern directions is longer than the length of the web plate by at least one rib.

[0015] In one embodiment, the web is cut at the end, and the angle between the web end line and the web side is 20°-25°.

[0016] The present invention also provides a bilge keel for a large LNG ship, comprising segmented bilge keels distributed on the outer plates of a hull segment. The installation position of the segmented bilge keel in each segment is the streamline closest to the center of the bilge in the hull segment. The streamline is obtained by a streamline test on a large LNG ship. There is a certain distance between adjacent segmented bilge keels, and the bow side of each segmented bilge keel is closer to the centerline of the hull than the stern side.

[0017] In one embodiment, the segmented bilge keel includes a web and a panel, one end of the web is fixed to the outer plate of the hull, the angle between the web and the bottom plate of the hull is 40°-50°, the panel is fixed to the end of the web away from the outer plate, the panel is perpendicular to the web, the web and the outer plate are fixedly connected by welding, a pad is provided between the web and the outer plate, the web is welded to the pad, and the pad is welded to the outer plate, the lengths of the web and the pad in the bow and stern directions are both longer than the length of the panel, the length of the pad in the bow and stern directions is longer than the length of the web, the web is cut at the end, and the angle between the end line of the web and the side edge of the web is 20°-25°.

[0018] Compared with the prior art, this application has at least the following beneficial effects:

[0019] The installation method of the bilge keel of a large LNG ship and the bilge keel of a large LNG ship in the present application, after a streamline test is carried out on the large LNG ship to obtain multiple streamlines, the streamline closest to the center of the bilge in each segment is selected as the installation position of the segmented bilge keel in the segment, so as to ensure the accuracy of the installation position of the bilge keel in each segment, thereby balancing the anti-roll effect and resistance of the bilge keel on the entire large LNG ship; the bilge keel of the large LNG ship includes multiple segmented bilge keels, and the segmented bilge keels can be installed simultaneously during the segmented construction, thereby improving the efficiency of ship construction; the lengths of the web and the pad in the segmented bilge keel in the bow and stern directions are both longer than the length of the panel, and the length of the pad in the bow and stern directions is longer than the length of the web, thereby reducing the structural stress concentration of the segmented bilge keel and improving the service life of the bilge keel of the large LNG ship. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is an expanded view of the bilge outer plate of a large LNG ship in an embodiment of the present application;

[0021] Figure 2 This is a cross-sectional view of a large LNG carrier in an embodiment of the present application;

[0022] Figure 3 This is a developed diagram of the bilge outer plate of a large LNG carrier after determining the internal streamlines of different sections in the embodiment of this application;

[0023] Figure 4 is a cross-sectional view of a bilge keel in an embodiment of the present application;

[0024] Figure 5 This is a front view of the bilge keel in the embodiment of the present application;

[0025] Figure 6 1 is a top view of the bilge keel in an embodiment of the present application.

[0026] Figure numerals: 01, large LNG carrier; 1, outer plate; 2, segmented bilge keel; 201, web; 202, face plate; 203, pad; 3, bilge bracket; 4, rib; 5, segment dividing line; 6, streamline; 7, bilge center; 8, bilge longitudinal; 9, ship lines. DETAILED DESCRIPTION

[0027] To make the objectives, technical solutions, and advantages of the present invention more clearly apparent, the present invention is described below using specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely illustrative and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0028] The terms used in this disclosure are for the purpose of describing specific embodiments only and are not intended to limit the disclosure. As used in this disclosure and the appended claims, the singular forms "a," "an," "the," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0029] It should be understood that although the terms first, second, third, etc. may be used in this disclosure to describe various information, such information should not be limited to these terms and should not be understood to indicate or imply relative importance. These terms are only used to distinguish information of the same type from each other. For example, first information may also be referred to as second information, and similarly, second information may also be referred to as first information without departing from the scope of this disclosure. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining."

[0030] In the description of the present invention, unless otherwise specified and limited, it should be noted that the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a mechanical connection or the internal communication between two components. It can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances.

[0031] In order to better understand the technical solution of the present invention, the present invention is described in detail below in conjunction with specific implementation methods.

[0032] A method for installing a bilge keel of a large LNG ship comprises the following steps:

[0033] S1. Conducting a streamline test on a large LNG ship to obtain multiple streamlines 6 on the outer plate 1 of the hull;

[0034] In this embodiment, a streamline test is conducted on a large LNG ship in a test pool using a ship model. The ship model is a model of a large LNG ship. The principle of the ship model test is to calculate the total resistance coefficient of the ship with a bilge keel using formula (1), and to estimate the total resistance of the ship based on the total resistance coefficient of the ship and geometric factors such as the hull line shape, and to obtain the streamline with the minimum resistance of the ship. The large LNG ship in this application is obtained in the streamline test as follows due to the ship size and linearity: Figure 1 、 Figure 2 A plurality of flow lines 6 are shown.

[0035]

[0036] in, τ is the friction shear force, Fs is the friction resistance, S is the wetted surface area, where ρ is the fluid density and U is the flow velocity.

[0037] S2, divide the hull into multiple sections according to the section dividing line 5 of the hull, and select the streamline 6 closest to the bilge center 7 in each section as the installation position of the section bilge keel 2 in the section, such as Figure 2 As shown, from the rear view of the hull, the marked cloud line is the overlap of the streamline 6 and the bilge center 7. This position is the installation position of the bilge keel. As shown in the figure, in different segment divisions, the streamline corresponding to the bilge center 7 is selected as the bilge keel. In this application, Figure 3 As shown in the figure, from the shell plate development diagram, the streamline selected in each segment is closer to the hull centerline toward the bow side than toward the stern side;

[0038] S3. Install segmented bilge keels 2 in each segment according to the streamline determined in S2, with a certain distance between the segmented bilge keels 2.

[0039] like Figure 4 As shown, the segmented bilge keel 2 includes a web 201, one end of which is fixed to the hull outer plating 1. The angle between the web 201 and the hull bottom plating is 40°-50°. In this embodiment, the angle between the web 201 and the hull bottom plating is 45°. The web 201 prevents the hull from rolling by blocking water. The segmented bilge keel 2 also includes a panel 202 fixed to the end of the web 201 away from the outer plating 1. The panel 202 is perpendicular to the web 201 and is provided to strengthen the web 201.

[0040] The web 201 and the outer plating 1 are fixedly connected by welding. A shim 203 is interposed between the web 201 and the outer plating 1. The web 201 is welded to the shim 203, which in turn is welded to the outer plating 1. The shim transitions between the web 201 and the outer plating 1, thereby increasing the rigidity of the bilge keel connection and improving the stability of the vessel during operation. The ends of the segmented bilge keel 2 are fixed to the shim 203 and the web 201 by full-penetration welding. The full-penetration weld length of the shim 203 is 200 mm, while the full-penetration weld length of the web 201 is 100 mm. In order to minimize the structural mutation at the end of the segmented bilge keel 2, the length of the web 201 and the pad 203 in the bow and stern directions are both longer than the length of the panel 202. The length of the pad 203 in the bow and stern directions is longer than the length of the web 201. The length of the pad 203 in the bow and stern directions is longer than the length of the web 201 by at least one rib. In this embodiment, the length of the pad 203 in the bow and stern directions is extended by one rib of the web 201 and then extended by 50mm. Figure 5 As shown, the web 201 is cut at the end, and the angle between the end line of the web 201 and the side of the web 201 is 20°-25°, thereby further alleviating the sudden change of the end of the segmented bilge keel 2.

[0041] This embodiment also discloses a bilge keel for a large LNG ship, comprising segmented bilge keels 2 distributed on the outer plating 1 of a hull segment. The segmented bilge keel 2 in each segment is installed at a streamline 6 closest to a bilge center 7 in the hull segment. The streamline is obtained by conducting streamline tests on large LNG ships. The segmented bilge keels 2 on the outer plating are zigzag-shaped, with a certain distance between adjacent segmented bilge keels 2. The bow side of each segmented bilge keel 2 is closer to the hull centerline than the stern side.

[0042] The segmented bilge keel 2 includes a web 201, one end of which is fixed to the hull plating 1. The angle between the web 201 and the hull bottom plating is 40°-50°. In this embodiment, the angle between the web 201 and the hull bottom plating is 45°. The segmented bilge keel 2 also includes a faceplate 202 fixed to the end of the web 201 away from the plating 1. The faceplate 202 is perpendicular to the web 201.

[0043] The web 201 and the outer plating 1 are fixedly connected by welding. A shim 203 is interposed between the web 201 and the outer plating 1. The web 201 is welded to the shim 203, which in turn is welded to the outer plating 1. The shim transitions between the web 201 and the outer plating 1, thereby increasing the rigidity of the bilge keel connection and improving the stability of the vessel during operation. The ends of the segmented bilge keel 2 are fixed to the shim 203 and the web 201 by full-penetration welding. The full-penetration weld length of the shim 203 is 200 mm, while the full-penetration weld length of the web 201 is 100 mm. In order to minimize the structural mutation at the end of the segmented bilge keel 2, the length of the web 201 and the pad 203 in the bow and stern directions are both longer than the length of the panel 202. The length of the pad 203 in the bow and stern directions is longer than the length of the web 201. The length of the pad 203 in the bow and stern directions is longer than the length of the web 201 by at least one rib. In this embodiment, the length of the pad 203 in the bow and stern directions is extended by one rib of the web 201 and then extended by 50mm. Figure 5 As shown, the web 201 is cut at the end, and the angle between the end line of the web 201 and the side of the web 201 is 20°-25°, thereby further alleviating the sudden change of the end of the segmented bilge keel 2.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solutions of the present invention. They should all be included in the scope of the technical solutions for which protection is sought in the present invention.

Claims

1. A method for installing a bilge keel of a large LNG ship, characterized in that: The following steps are involved: S1. Conduct streamline tests on large LNG carriers and obtain multiple streamlines on the outer plate of the hull; S2. Divide the hull into multiple sections according to the hull's section dividing lines, and select the streamline closest to the bilge center in each section as the installation position of the section bilge keel in that section, wherein the streamline selected in each section is closer to the hull centerline toward the bow side than toward the stern side; S3. Install segmented bilge keels in each segment according to the streamline determined in S2, with a certain distance between the segmented bilge keels.

2. The method for installing a large LNG ship bilge keel according to claim 1, characterized in that: The segmented bilge keel comprises a web, one end of which is fixed to the outer plate of the hull, and an angle between the web and the bottom plate of the hull is 40°-50°.

3. The method for installing a large LNG ship bilge keel according to claim 2, characterized in that: The segmented bilge keel further includes a panel fixed to an end of the web away from the outer plate, and the panel is perpendicular to the web.

4. The method for installing a large LNG ship bilge keel according to claim 2, characterized in that: The web and the outer plate are fixedly connected by welding, a pad is provided between the web and the outer plate, the web is welded to the pad, and the pad is welded to the outer plate.

5. The method for installing a large LNG ship bilge keel according to claim 4, characterized in that: The ends of the segmented bilge keels are fixed with a pad and a web by full penetration welding. The length of the full penetration welding of the pad is 200 mm, and the length of the full penetration welding of the web is 100 mm.

6. The method for installing a large LNG ship bilge keel according to claim 4, characterized in that: The lengths of the web and the pad in the bow and stern directions are both longer than the length of the panel, and the length of the pad in the bow and stern directions is longer than the length of the web.

7. The method for installing a large LNG ship bilge keel according to claim 6, characterized in that: The length of the pad in the bow and stern directions is longer than the length of the web by at least one rib.

8. The method for installing a large LNG ship bilge keel according to claim 2, characterized in that: The web is cut at the end, and the angle between the web end line and the web side is 20°-25°.

9. A large LNG ship bilge keel, characterized in that: It includes segmented bilge keels distributed on the outer plate of the hull section. The installation position of the segmented bilge keel in each section is the streamline closest to the center of the bilge in the hull section. The streamline is obtained from streamline tests on large LNG ships. There is a certain distance between adjacent segmented bilge keels. The bow side of each segmented bilge keel is closer to the centerline of the hull than the stern side.

10. The method for installing a large LNG ship bilge keel according to claim 9, characterized in that: The segmented bilge keel includes a web and a panel, one end of the web is fixed to the outer plate of the hull, the angle between the web and the bottom plate of the hull is 40°-50°, the panel is fixed to the end of the web away from the outer plate, the panel is perpendicular to the web, the web and the outer plate are fixedly connected by welding, a pad is provided between the web and the outer plate, the web is welded to the pad, and the pad is welded to the outer plate, the lengths of the web and the pad in the bow and stern directions are both longer than the length of the panel, the length of the pad in the bow and stern directions is longer than the length of the web, the web is cut at the end, and the angle between the end line of the web and the side of the web is 20°-25°.

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