A method for solving the problem of wave motion of a floating body based on three-dimensional potential flow theory

Abstract

The application discloses a method for solving the problem of wave motion of a floating body based on three-dimensional potential flow theory, which constructs an offshore photovoltaic floating power station based on various construction factors; uses a multi-point mooring mode to fix the offshore photovoltaic floating power station in a preset area; determines a reference coordinate system and a body coordinate system of the offshore photovoltaic floating power station in the preset area; and solves the motion mode of the multi-floating body in a near-sea water area according to the reference coordinate system and the body coordinate system and the three-dimensional potential flow theory. The three-dimensional potential flow theory is used to improve the calculation efficiency of the motion problem.

Description

Technical Field

[0001] This invention relates to the field of motion problem solving technology, and in particular to a method for solving the wave motion problem of a floating body based on three-dimensional potential flow theory. Background Technology

[0002] Solving the linearized velocity potential problem based on three-dimensional source distribution technology requires approximating the wetted surface area of ​​the hull by using multiple planar elements to represent the source-sink distribution, which helps describe the fluid velocity potential. The accuracy and computational efficiency of this method are key technical issues. It is necessary to calculate wave loads and the motion response of freely floating or moored structures in regular waves, including hydrodynamic interference between them. This requires software capable of handling complex fluid-structure interactions. Using the rigid cap assumption to suppress the effects of irregular frequencies, damping caps can be used to control free surface resonant motion, such as in the gaps between side-by-side moored vessels. Input data includes the structure's geometry, center of gravity location, triaxial radius of inertia, and water depth. Output data includes fluid reaction forces and moments, first-order wave excitation forces and moments, and response amplitude and phase operators, which are crucial for strength analysis and drift force analysis. Accurate prediction of the hull's motion response is significant for wave load calculation and rational structural design. The motion of ships in large waves exhibits significant nonlinearity, while current seakeeping predictions mostly use linear slicing methods. Improving the accuracy of numerical prediction is a technical challenge. During offshore operations, it is necessary for ships and marine engineering equipment to maintain stable positions, or for different floating devices to maintain their relative positions when working together to complete a task. The development of wave compensation technology and devices initially focused on wave-compensating cranes, and while it is now relatively mature, the majority of suppliers are foreign companies, gradually creating technological barriers and monopolizing the market. Based on three-dimensional potential flow theory, this paper compares and analyzes the hydrodynamic motion response of multi-buoy coupling with that of a single-buoy, studying the impact of coupling effects on the motion of the floating bodies. Summary of the Invention

[0003] The present invention aims to at least partially solve one of the technical problems in the related art.

[0004] To address this, this invention proposes a method for solving the wave motion problem of floating bodies based on three-dimensional potential flow theory. It can calculate the wave loads and motion responses of freely floating or moored structures in regular waves, including hydrodynamic disturbances between them. This method is applicable to both shallow and deep water environments and has been validated by experimental results from multiple physical models.

[0005] To achieve the above objectives, another aspect of the present invention proposes a solution system for the wave motion problem of a floating body based on three-dimensional potential flow theory.

[0006] To achieve the above objectives, this invention proposes a method for solving the wave motion problem of a floating body based on three-dimensional potential flow theory, comprising:

[0007] The optimization objective and constraints of the marine renewable energy integrated utilization system are determined, and the optimal configuration of the marine renewable energy integrated utilization system is performed using the particle swarm optimization algorithm; wherein, the particle swarm optimization algorithm process is as follows:

[0008] S1 is a floating photovoltaic power station built based on various construction factors.

[0009] S2 uses multi-point mooring to fix the offshore photovoltaic floating power station in a preset area;

[0010] S3, determine the reference coordinate system and the body coordinate system of the offshore photovoltaic floating power station in the preset area;

[0011] S4. Solve the motion mode of the multi-buoy in nearshore waters based on the reference coordinate system, the body coordinate system, and the three-dimensional potential flow theory.

[0012] To achieve the above objectives, a second aspect of this application proposes a solution system for the wave motion problem of a floating body based on three-dimensional potential flow theory, comprising:

[0013] Multi-floating body building modules are used to construct offshore photovoltaic floating power plants based on various construction factors;

[0014] Multi-point mooring module, used to fix offshore photovoltaic floating power station in a preset area by using multi-point mooring;

[0015] The coordinate system determination module is used to determine the reference coordinate system and the body coordinate system of the offshore photovoltaic floating power station in the preset area;

[0016] The motion problem-solving module is used to solve the motion mode of the multi-buoy in nearshore waters based on the reference coordinate system, the body coordinate system, and the three-dimensional potential flow theory.

[0017] This invention presents a method and system for solving wave motion problems of floating bodies based on three-dimensional potential flow theory. It can calculate the wave loads and motion responses of freely floating or moored structures in regular waves, including hydrodynamic disturbances between them. This method is applicable to both shallow and deep water environments and has been validated by experimental results from multiple physical models. Based on three-dimensional source distribution technology, by approximating the wetted surface area of ​​the hull as multiple planar elements, each representing a source-sink distribution, it helps to describe the velocity potential of the fluid, thereby improving computational efficiency.

[0018] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0019] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0020] Figure 1 This is a flowchart of a method for solving the wave motion problem of a floating body based on three-dimensional potential flow theory according to an embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of the coordinate system according to an embodiment of the present invention;

[0022] Figure 3 This is a structural diagram of a system for solving the wave motion problem of a floating body based on three-dimensional potential flow theory according to an embodiment of the present invention. Detailed Implementation

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0024] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0025] The following describes, with reference to the accompanying drawings, a method and system for solving the wave motion problem of a floating body based on three-dimensional potential flow theory, according to an embodiment of the present invention.

[0026] like Figure 1 As shown, the method of the present invention includes:

[0027] S1 is a floating photovoltaic power station built based on various construction factors.

[0028] S2 uses multi-point mooring to fix the offshore photovoltaic floating power station in a preset area;

[0029] S3, determine the reference coordinate system and the body coordinate system of the offshore photovoltaic floating power station in the preset area;

[0030] S4. Solve the motion mode of the multi-buoy in nearshore waters based on the reference coordinate system, the body coordinate system, and the three-dimensional potential flow theory.

[0031] This invention simplifies the floating structure and its surrounding near-shore sea conditions. The basic assumptions are as follows:

[0032] (1) The fluid is an ideal fluid that is non-rotating, non-viscous, and incompressible.

[0033] (2) Ignore flexible deformation and assume that the floating modules in the floating system are rigid bodies.

[0034] (3) Waves are viewed as micro-waves.

[0035] Based on the above assumptions and using the potential flow theory to solve the motion problem of the floating body to the waves, when studying the motion of marine floating structures, the flexible deformation of the floating body structure is usually ignored, and it is regarded as a rigid body that can perform complex six-degree-of-freedom motion on the sea surface.

[0036] The research object of this invention is an offshore photovoltaic floating power station, a novel floating structure without autonomous movement capability, which is fixed in a specific water area using a multi-point mooring method. In this case, the fixed coordinate system coincides with the reference coordinate system. To describe the motion of this type of structure on waves, two coordinate systems are used: the reference coordinate system and the body coordinate system, as follows: Figure 2 As shown.

[0037] When constructing offshore floating photovoltaic power plants, various construction factors need to be considered to ensure the safety, stability, economic viability, and environmental friendliness of the power plant. The following are some key factors and corresponding solutions:

[0038] Marine Environmental Adaptability: The design must consider the unique characteristics of the marine environment, such as high temperature, high humidity, and high salt spray, placing higher demands on equipment selection and system optimization. Equipment must possess corrosion resistance, high and low temperature resistance, and UV resistance. Special attention must be paid to the stable operation of electrical components such as photovoltaic modules, inverters, transformer substations, and cables in extreme marine environments. Structural Design: The design of photovoltaic support structures and foundations is crucial, requiring consideration of component tilt angles and steel structure stability. Currently, offshore photovoltaic support structures primarily employ large-span designs to reduce costs and ensure system stability and safety. For floating photovoltaic power stations, the floating structure design must consider stability, safety, and equipment corrosion resistance to cope with the combined effects of various loads such as sea winds, waves, and currents. Construction Organization: Efficiently utilize the offshore construction window and optimize the layout of wharves and storage yards to ensure the smooth assembly and installation of photovoltaic support structures and other equipment. Special attention should be paid to the survey and selection of submarine cable landing points to ensure smooth and safe power transmission. Technological Innovation: The introduction of a floating photovoltaic platform process reduces the impact of platform prefabrication on offshore operation schedules, simplifies construction organization, and lowers the risk of platform deformation during hoisting. A new, specialized typhoon-resistant flexible support system was developed and validated through wind tunnel testing, ensuring resistance to typhoons of force 12 or higher. Material Selection: High-efficiency, marine-atmospheric corrosion-resistant steel was selected to enhance corrosion resistance and provide a new option for materials used in marine photovoltaic power station supports. The design incorporates anti-corrosion frames, waterproof caps, and dust caps, combined with double-glass + double-POE high-water-resistance encapsulation technology, ensuring stable operation of the tidal flat photovoltaic power station throughout its entire lifecycle.

[0039] Based on the fundamental assumptions of the wave problem described above, this invention explores the motion of multi-buoyed bodies in nearshore waters. The commonly used surface element method is based on the fundamental solution of the Laplace equation, which is as follows:

[0040]

[0041] Boundary conditions include:

[0042] Surface conditions:

[0043]

[0044] In the formula, S represents the surface of the object, and Un represents the normal velocity of the surface of the object, which characterizes the impenetrability of the surface of the object;

[0045] Underwater conditions:

[0046]

[0047] In the formula, H represents the water depth, which characterizes the impenetrability of the seabed;

[0048] Free surface conditions:

[0049]

[0050] Boundary conditions at infinity:

[0051] That is, the Sommerfeld radiation condition, where diffracted and radiated waves propagate outwards at infinity:

[0052]

[0053]

[0054] in, For diffraction, Let c be the radiation potential and c be the wave velocity.

[0055] According to the linear potential flow theory, the velocity potential is decomposed into incident potential, diffraction potential, and radiation potential:

[0056]

[0057] In the formula, Let the incident wave velocity potential be... For diffraction, This represents the radiation potential.

[0058] Based on the assumption that the floating body undergoes small-amplitude simple harmonic oscillations near its equilibrium position on the waves, the time factor is separated, and the fluid velocity potential is expressed as:

[0059]

[0060] The spatial velocity potential can be expressed as a linear superposition of the incident potential, diffraction potential, and radiation potential:

[0061]

[0062] The method for solving the wave motion problem of floating bodies based on three-dimensional potential flow theory according to embodiments of the present invention can calculate the wave loads and motion responses of freely floating or moored structures in regular waves, including hydrodynamic interference between them. By approximating the wetted surface area of ​​the hull as multiple planar elements, each representing the source-sink distribution, it is helpful to describe the velocity potential of the fluid, thereby improving computational efficiency. The rigid cap assumption method is used to suppress the influence of irregular frequencies, and the damping cap can be used to control the resonant motion of the free surface, such as the intervals between side-by-side moored vessels. It can output data including fluid reaction forces and moments, first-order wave excitation forces and moments, response amplitudes and phase operators, which are crucial for strength analysis and drift force analysis. A solution algorithm for the three-dimensional time-domain nonlinear motion response of articulated multi-floating bodies is implemented, and the accuracy of the indirect time-domain method and the solution algorithm for the hydrodynamic response of articulated multi-floating bodies is verified by comparing the results with those from tank experiments and classical literature.

[0063] Furthermore, such as Figure 3 As shown, this invention also proposes a solution system 10 for the wave motion problem of a floating body based on three-dimensional potential flow theory, comprising:

[0064] Multi-floating body building module 100 is used to construct offshore photovoltaic floating power stations based on various construction factors;

[0065] Multi-point mooring module 200 is used to fix an offshore photovoltaic floating power station in a preset area using multi-point mooring;

[0066] The coordinate system determination module 300 is used to determine the reference coordinate system and the body coordinate system of the offshore photovoltaic floating power station in the preset area;

[0067] The motion problem solving module 400 is used to solve the motion mode of the multi-buoy in nearshore waters based on the reference coordinate system, the body coordinate system, and the three-dimensional potential flow theory.

[0068] Furthermore, the Laplace equation is formulated as follows:

[0069]

[0070] Furthermore, the boundary conditions include:

[0071] Surface conditions:

[0072]

[0073] In the formula, S represents the surface of the object, and Un represents the normal velocity of the surface of the object, which characterizes the impenetrability of the surface of the object;

[0074] Underwater conditions:

[0075]

[0076] In the formula, H represents the water depth, which characterizes the impenetrability of the seabed;

[0077] Free surface conditions:

[0078]

[0079] Boundary conditions at infinity:

[0080] That is, the Sommerfeld radiation condition, where diffracted and radiated waves propagate outwards at infinity:

[0081]

[0082]

[0083] in, For diffraction, Let c be the radiation potential and c be the wave velocity. Furthermore, according to the linear potential flow theory, the velocity potential is decomposed into incident potential, diffraction potential, and radiation potential:

[0084] In the formula, Let the incident wave velocity potential be... For diffraction, This represents the radiation potential.

[0085] Furthermore, based on the assumption that the floating body undergoes small-amplitude simple harmonic oscillations near its equilibrium position on the waves, the time factor is separated, and the fluid velocity potential is expressed as:

[0086]

[0087] The spatial velocity potential can be expressed as a linear superposition of the incident potential, diffraction potential, and radiation potential:

[0088]

[0089] The system for solving wave motion problems of floating bodies based on three-dimensional potential flow theory according to embodiments of the present invention can calculate the wave loads and motion responses of freely floating or moored structures in regular waves, including hydrodynamic disturbances between them. By approximating the wetted surface area of ​​the hull as multiple planar elements, each representing a source-sink distribution, it is helpful to describe the velocity potential of the fluid, thereby improving computational efficiency. The rigid cap assumption method is used to suppress the influence of irregular frequencies, and the damping cap can be used to control the resonant motion of the free surface, such as the intervals between side-by-side moored vessels. It can output data including fluid reaction forces and moments, first-order wave excitation forces and moments, response amplitudes and phase operators, which are crucial for strength analysis and drift force analysis. A solution algorithm for the three-dimensional time-domain nonlinear motion response of articulated multi-floating bodies is implemented, and the accuracy of the indirect time-domain method and the solution algorithm for the hydrodynamic response of articulated multi-floating bodies is verified by comparing the results with those from tank experiments and classical literature.

[0090] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0091] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

Claims

1. A method for solving the wave motion problem of a floating body based on three-dimensional potential flow theory, characterized in that, include: Constructing offshore photovoltaic floating power stations based on multiple construction factors; The offshore photovoltaic floating power station is fixed in a predetermined area using a multi-point mooring method; Determine the reference coordinate system and the body coordinate system of the offshore photovoltaic floating power station in the preset area; The motion of the multi-buoy in nearshore waters is solved based on the reference coordinate system, the body coordinate system, and the three-dimensional potential flow theory.

2. The method according to claim 1, characterized in that, The formula for the Laplace equation is:

3. The method according to claim 1, characterized in that, Boundary conditions include: Surface conditions: In the formula, S represents the surface of the object, and Un represents the normal velocity of the surface of the object, which characterizes the impenetrability of the surface of the object; Underwater conditions: In the formula, H represents the water depth, which characterizes the impenetrability of the seabed; Free surface conditions: Boundary conditions at infinity: That is, the Sommerfeld radiation condition, where diffracted and radiated waves propagate outwards at infinity: in, For diffraction, Let c be the radiation potential and c be the wave velocity.

4. The method according to claim 3, characterized in that, According to the linear potential flow theory, the velocity potential is decomposed into incident potential, diffraction potential, and radiation potential: In the formula, Let the incident wave velocity potential be... For diffraction, This represents the radiation potential.

5. The method according to claim 4, characterized in that, Based on the assumption that the floating body undergoes small-amplitude simple harmonic oscillations near its equilibrium position on the waves, the time factor is separated, and the fluid velocity potential is expressed as: The spatial velocity potential can be expressed as a linear superposition of the incident potential, diffraction potential, and radiation potential:

6. A solution system for the wave motion problem of a floating body based on three-dimensional potential flow theory, characterized in that, include: Multi-floating body building modules are used to construct offshore photovoltaic floating power plants based on various construction factors; Multi-point mooring module, used to fix offshore photovoltaic floating power station in a preset area by using multi-point mooring; The coordinate system determination module is used to determine the reference coordinate system and the body coordinate system of the offshore photovoltaic floating power station in the preset area; The motion problem-solving module is used to solve the motion mode of the multi-buoy in nearshore waters based on the reference coordinate system, the body coordinate system, and the three-dimensional potential flow theory.

7. The system according to claim 6, characterized in that, The formula for the Laplace equation is:

8. The system according to claim 7, characterized in that, Boundary conditions include: in, For diffraction, Let c be the radiation potential and c be the wave velocity.

9. The system according to claim 8, characterized in that, According to the linear potential flow theory, the velocity potential is decomposed into incident potential, diffraction potential, and radiation potential: In the formula, Let the incident wave velocity potential be... For diffraction, This represents the radiation potential.

10. The system according to claim 9, based on the assumption that the floating body undergoes small-amplitude simple harmonic oscillations near its equilibrium position on the waves, separates the time factor and expresses the fluid velocity potential as: The spatial velocity potential can be expressed as a linear superposition of the incident potential, diffraction potential, and radiation potential:

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