Design method of stern side thrust hole

Abstract

The invention provides a stern side thrust hole design method, which comprises the following steps: S1, calculating pressure distribution and streamline distribution of the surface of a ship body; S2, determining the position of a stern side thrust hole; S3, designing a diversion trench based on the position of the side thrust hole: outwards extending the diversion trench by taking the side thrust hole as the center of a horn mouth to form a horn mouth structure with a deep inner part and a shallow outer part; the center point of a first arc at the front end of the intersecting periphery of the flow guide grooves right faces the water flow direction in streamline distribution of the tail of the ship. The water flow passes through the central point of the second arc at the tail end of the diversion trench; and S4, designing grids in the side pushing hole, wherein the first grid is parallel to the water flow direction, and the second grid is perpendicular to the first grid. According to the design method of the stern lateral thrust hole, the resistance of the ship body after the hole is formed is effectively reduced, through the shape and depth design of the diversion trenches, the pressure distribution at the diversion trenches is uniform and gentle, the pressure gradient is small, the transition is smooth, local stress concentration and flow separation are reduced, and the resistance of the small stern lateral thrust hole to the ship body is reduced; and the influence on the rapidity of the ship is reduced.

Description

Technical Field

[0001] The present invention relates to the field of shipbuilding, and particularly to a design method for a stern side thruster hole. Background Art

[0002] When a ship is berthing or navigating, in order to improve the maneuverability of the ship, it is usually necessary to install side thruster devices at the bow or stern of the ship. Installing side thruster devices requires opening holes at both the bow and stern ends, with a hole diameter of 1.5 - 2 meters. The bow is close to Station 19, and the stern is close to Station 2. These are positions where the ship's hull lines change greatly, and it is easy to generate eddy currents, increasing the hull resistance. Especially for the stern side thruster hole, which is close to the propeller disk plane. If eddy currents are generated, it will not only increase the resistance but also reduce the propulsion efficiency, having a greater impact on the ship's speed performance.

[0003] Domestic and foreign literature has detailed design methods for the bow side thruster hole, but there is a lack of relevant research on the optimization design of the stern side thruster hole. In the existing scheme, when opening a side thruster hole at the stern, the design method of the bow side thruster hole is generally applied, which not only increases the hull resistance but also affects the propulsion efficiency, reducing the speed performance. Therefore, how to design the stern side thruster hole to reduce the resistance to the hull and improve the speed performance has become a technical problem that needs to be solved urgently. Summary of the Invention

[0004] In order to solve the problem that the stern side thruster hole increases the hull resistance and affects the speed performance, the present invention proposes a design method for a stern side thruster hole to reduce the resistance of the stern side thruster hole to the hull and its impact on the speed performance.

[0005] The present invention provides the following specific solutions:

[0006] A design method for a stern side thruster hole includes the following steps:

[0007] S1. Calculate the pressure distribution and streamline distribution on the hull surface: Create a three-dimensional model of the hull, divide grid cells, and set boundary conditions, where the boundary conditions include: the flow velocity of the fluid, pressure, set draft, and ship speed; Calculate the pressure distribution and streamline distribution on the stern surface based on the grid cells and boundary conditions;

[0008] S2. Determine the position of the stern side thruster hole: Set the horizontal position of the center of the circular side thruster hole at the stern based on the cabin layout, modify the height of the center of the side thruster hole relative to the sea level, calculate the pressure distribution on the stern surface with the side thruster hole at different heights, and select the height of the side thruster hole with the minimum resistance value as the position of the side thruster hole;

[0009] S3. Design the flow guide groove based on the position of the side thruster hole: The flow guide groove extends outward from the center of the flare opening of the side thruster hole to form a flare structure. The flare structure is a structure with a deeper inner part and a shallower outer part that is recessed from the hull surface into the hull. The intersection outer perimeter where the flare structure intersects with the hull surface is in the shape of the outer perimeter of a water droplet longitudinal section with a round front and a pointed rear; the center point of the first arc at the front end of the intersection outer perimeter of the flow guide groove faces the water flow direction in the streamline distribution at the ship's tail; and the water flow passes through the center point position of the second arc at the tail end of the flow guide groove.

[0010] S4: Design the grille inside the side thruster hole: Design a grille inside the side thruster hole. The first grille is parallel to the water flow direction, and the second grille is perpendicular to the first grille.

[0011] Preferably, step S1 includes:

[0012] S11. Solve the system of equations: Use a CFD solver to solve the fluid mechanics system of equations based on the boundary conditions and the three-dimensional model to obtain the pressure distribution and streamline distribution on the ship's tail surface.

[0013] S12. Post-processing: Perform post-processing on the solution results and draw the pressure distribution diagram and streamline distribution diagram.

[0014] Preferably, step S3 further includes: Calculate the pressure distribution of the ship's tail with the flow guide groove, and change the depression depth of the flow guide groove to make it conform to the change of the set pressure gradient threshold.

[0015] Preferably, the intersection line of the center points of the first arc and the second arc of the flow guide groove is the symmetry line of the flow guide groove, and the center point of the circular side thruster hole is located on the symmetry line.

[0016] Preferably, the length of the symmetry line of the flow guide groove is 2d - 2.5d, the connection line between the two end points of the first arc does not exceed 1.5d, and the side thruster hole is arranged inside the flow guide groove, where d is the diameter of the side thruster hole.

[0017] Preferably, the depression depth of the flow guide groove does not exceed 300 mm.

[0018] Preferably, the grille adopts a 3*5 specification or a 4*4 specification.

[0019] Preferably, the angle formed by the second grille and the plane perpendicular to the flow field direction is 0 - 45 degrees.

[0020] The beneficial effects of the present invention:

[0021] The present invention provides a design method for a stern side thrust hole. S1. Calculate the pressure distribution and streamline distribution on the hull surface: Create a three-dimensional model of the hull, divide the grid cells, and set the boundary conditions, where the boundary conditions include: the flow velocity of the fluid, pressure, set draft, and ship speed; Calculate the pressure distribution and streamline distribution on the stern surface based on the grid cells and boundary conditions. S2. Determine the position of the side thrust hole at the stern: Set the horizontal position of the center of the circular side thrust hole at the stern based on the cabin layout, modify the height of the center of the side thrust hole relative to the sea level, calculate the pressure distribution on the stern surface with the side thrust hole at different heights, and select the height of the side thrust hole with the minimum resistance value as the position of the side thrust hole. The present invention calculates the hull resistance value and the pressure distribution and streamline distribution on the surface, and reasonably selects the opening position of the side thrust hole through the change of the hull resistance value, effectively reducing the hull resistance after opening the hole. S3. Design the flow guide groove based on the position of the side thrust hole: The flow guide groove extends outward from the center of the flare of the side thrust hole to form a flare structure, and the flare structure is a structure with a deeper inner part and a shallower outer part that is recessed from the hull surface to the inside of the hull. The intersecting outer periphery of the flare structure intersecting with the hull surface is in the shape of the outer periphery of a water droplet longitudinal section with a round front and a pointed rear; The center point of the first arc at the front end of the intersecting outer periphery of the flow guide groove is directly opposite to the water flow direction in the streamline distribution at the stern of the ship; And the water flow passes through the center point position of the second arc at the end of the flow guide groove. The present invention designs the shape, size, and grooving depth of the flow guide groove based on the pressure distribution and streamline distribution on the hull surface, making the pressure distribution at the side thrust hole and the flow guide groove uniform and gentle, with a small pressure gradient and a smooth transition, reducing local stress concentration and flow separation, and reducing the resistance of the stern side thrust hole to the hull and its impact on the ship's speed. S4: Design the grille inside the side thrust hole: Design a grille inside the side thrust hole, where the first grille is parallel to the water flow direction, and the second grille is perpendicular to the first grille. The present invention adds a grille structure design at the opening of the side thrust hole and the second grille has a deflection angle to reduce resistance, further reducing the resistance of the stern side thrust hole to the hull and its impact on the ship's speed. Description of the Drawings

[0022] Figure 1 It is a flowchart of a design method for a stern side thrust hole provided by the present invention.

[0023] Figure 2 It is a schematic diagram of the side thrust hole structure in a design method for a stern side thrust hole provided by the present invention.

[0024] 1 - First arc; 2 - First boundary; 3 - Second arc; 4 - Second boundary; 5 - First grille; 6 - Second grille. Detailed Embodiment

[0025] The following further describes the present invention in conjunction with the drawings and embodiments.

[0026] As Figure 1As shown in the figure, a design method for the side thrust hole at the stern of a ship includes the following steps:

[0027] S1. Calculate the pressure distribution and streamline distribution on the hull surface: Create a three-dimensional model of the hull, divide the grid cells, and set the boundary conditions, which include: the flow velocity of the fluid, pressure, set draft, and ship speed; Calculate the pressure distribution and streamline distribution on the stern surface based on the grid cells and boundary conditions;

[0028] S2. Determine the position of the side thrust hole at the stern: Set the horizontal position of the center of the circular side thrust hole at the stern based on the cabin layout, modify the height of the center of the side thrust hole relative to the sea level, calculate the pressure distribution on the stern surface with the side thrust hole at different heights, and select the height of the side thrust hole with the minimum resistance value as the position of the side thrust hole;

[0029] S3. Design the flow guiding groove based on the position of the side thrust hole: The flow guiding groove extends outward from the center of the flare of the side thrust hole to form a flare structure. The flare structure is a structure with a deeper inner part and a shallower outer part that is recessed from the hull surface. The intersection outer perimeter of the flare structure and the hull surface is in the shape of the outer perimeter of a water droplet longitudinal section with a round front and a pointed rear; The center point of the first arc 1 at the front end of the intersection outer perimeter of the flow guiding groove is directly opposite to the water flow direction in the streamline distribution at the stern of the ship; And the center point position of the second arc 3 at the end of the water flow through the flow guiding groove; The first arc 1 and the second arc 3 are connected by the first boundary 2 and the second boundary 4 to form the outer edge of the flow guiding groove.

[0030] S4: Design the grille inside the side thrust hole: Design a grille inside the side thrust hole. The first grille 5 is parallel to the water flow direction, and the second grille 6 is perpendicular to the first grille 5.

[0031] The design of the flow guiding groove and the grille is as Figure 2 shown in the figure.

[0032] Preferably, step S1 includes:

[0033] S11. Solve the equations: Use a CFD solver to solve the fluid mechanics equations based on the boundary conditions and the three-dimensional model to obtain the pressure distribution and streamline distribution on the stern surface;

[0034] S12. Post-processing: Perform post-processing on the solution results and draw the pressure distribution diagram and streamline distribution diagram.

[0035] Preferably, step S3 further includes: Calculate the pressure distribution of the stern with the flow guiding groove, and change the depression depth of the flow guiding groove to make it conform to the change of the set pressure gradient threshold.

[0036] Preferably, the intersection line of the center points of the first arc 1 and the second arc 2 of the flow guiding groove is the symmetry line of the flow guiding groove, and the center point of the circular side thrust hole is located on the symmetry line.

[0037] Preferably, the length of the symmetry line of the diversion groove is 2d - 2.5d, the connection line of the two end points of the first arc 1 does not exceed 1.5d, and the side thrust holes are arranged in the diversion groove, where d is the diameter of the side thrust holes.

[0038] Preferably, the depression depth of the diversion groove does not exceed 300 mm.

[0039] Preferably, the grille adopts a 3*5 specification or a 4*4 specification.

[0040] Preferably, the included angle between the second grille 6 and the plane formed by the vertical flow field direction is 0 - 45 degrees.

[0041] It should be noted that the above specific embodiments can enable those skilled in the art to understand the present invention more comprehensively, but do not limit the present invention in any way. Therefore, although this specification has described the present invention in detail with reference to the drawings and embodiments, those skilled in the art should understand that the present invention can still be modified or equivalently replaced. In short, all technical solutions and their improvements that do not depart from the spirit and scope of the present invention should be covered by the protection scope of the patent of the present invention.

Claims

1. A method for designing a stern thrust hole, characterized in that: The steps include: S1. Calculate the pressure distribution and streamline distribution on the hull surface: create a three-dimensional model of the hull, divide the grid units, and set boundary conditions, the boundary conditions include: fluid velocity, pressure, set draft depth, speed; calculate the pressure distribution and streamline distribution on the stern surface based on the grid units and boundary conditions; S2. Determine the position of the thrust hole at the stern: set the horizontal position of the center of the circular thrust hole at the stern based on the cabin layout, modify the height of the center of the thrust hole relative to the sea level, calculate the pressure distribution of the stern surface with the thrust hole at different heights, and select the thrust hole height with the smallest resistance value as the position of the thrust hole; S3. Design the guide groove based on the position of the side thrust hole: the guide groove extends outward from the side thrust hole as the center of the bell mouth to form a bell mouth structure, the bell mouth structure is a structure that is deep inside and shallow outside and is formed by sinking from the hull surface to the inside of the hull, and the intersecting outer periphery of the bell mouth structure and the hull surface is in the shape of the outer periphery of the longitudinal section of a water drop that is round in front and pointed in the back; the center point of the first arc at the front end of the intersecting outer periphery of the guide groove faces the water flow direction in the streamline distribution of the stern of the ship; and the water flows through the center point position of the second arc at the tail end of the guide groove; S4: Design of grille in the side push hole: A grille is designed in the side push hole, the first grille is parallel to the water flow direction, and the second grille is perpendicular to the first grille.

2. The method for designing a stern thrust hole according to claim 1, characterized in that: Step S1 includes: S11. Solving the equations: using a CFD solver to solve the fluid mechanics equations based on the boundary conditions and the three-dimensional model to obtain the pressure distribution and streamline distribution on the stern surface; S12. Post-processing: Post-process the solution results and draw pressure distribution diagrams and streamline distribution diagrams.

3. The method for designing a stern thrust hole according to claim 1, characterized in that: Step S3 also includes: calculating the pressure distribution of the stern with the guide groove, and changing the depression depth of the guide groove to make it conform to the change of the set pressure gradient threshold.

4. The method for designing a stern thrust hole according to claim 1, characterized in that: The intersection line of the center points of the first arc and the second arc of the guide groove is the symmetry line of the guide groove, and the center point of the circular side push hole is located on the symmetry line.

5. The method for designing a stern thrust hole according to claim 1, characterized in that: The length of the symmetry line of the guide groove is 2d-2.5d, the line connecting the two end points of the first arc does not exceed 1.5d, the side push hole is arranged in the guide groove, and d is the diameter of the side push hole.

6. The method for designing a stern thrust hole according to claim 4, characterized in that: The recessed depth of the guide groove does not exceed 300 mm.

7. The method for designing a stern thrust hole according to claim 1, characterized in that: The grille adopts a 3*5 specification or a 4*4 specification.

8. The method for designing a stern thrust hole according to claim 1, characterized in that: The included angle between the second grid and the plane formed by the vertical flow field direction is 0-45 degrees.

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