Method for rapidly correcting hydrodynamic load of large-diameter cylinder structure

Abstract

The invention relates to the technical field of ocean engineering, and discloses a hydrodynamic load quick correction method for a large-diameter cylinder structure, which comprises the following steps of: establishing a digital model of a mixed structure comprising the large-diameter cylinder structure and defining a load working condition; aiming at the working condition, calculating an initial hydrodynamic load and an accurate hydrodynamic load according to a Morison formula and a three-dimensional potential flow theory respectively; generating a corresponding hydrodynamic load correction coefficient according to the ratio of the accurate hydrodynamic load to the initial hydrodynamic load; finally, the correction coefficient is applied to the initial hydrodynamic load, and the corrected hydrodynamic load is obtained and used for structural analysis. According to the method, the rapid calculation result is calibrated through the pre-generated correction coefficient, the problem that calculation efficiency and precision are difficult to consider at the same time in the prior art is solved, and the load calculation efficiency and engineering applicability are improved on the premise that the calculation precision is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of marine engineering technology, specifically to a method for rapid correction of hydrodynamic loads on a large-diameter cylindrical structure. Background Technology

[0002] In the field of marine engineering, hybrid structures combining jackets and large-diameter cylinders (such as wind turbine jacket foundations) are increasingly widely used. Accurate calculation of wave and hydrodynamic loads is a crucial step in structural analysis (such as stress analysis or fatigue analysis) of these structures.

[0003] Currently, there are two main methods commonly used in the industry for calculating hydrodynamic loads.

[0004] The first method is based on the Morison formula. This method is simple and fast to calculate, and provides acceptable results when applied to small-scale components (such as the rods of a jacket structure). However, for large-diameter cylindrical sections in hybrid structures, their scale relative to the wavelength is not negligible, and the wave diffraction effect is significant. The Morison formula does not fully account for this diffraction effect, and if it is directly applied to large-diameter cylinders, it will produce a large calculation deviation, resulting in insufficient accuracy of the load calculation results.

[0005] The second type is a numerical method based on three-dimensional potential flow theory (such as the boundary element method). This method can accurately simulate the diffraction effect of waves and accurately calculate the hydrodynamic loads on large-scale structures.

[0006] However, a key technical challenge exists in engineering practice: mainstream marine engineering structural analysis software (used for stress and fatigue analysis) typically only supports load application methods based on the Morison formula in its wave load calculation modules or interfaces. This type of software lacks a three-dimensional potential flow theory calculation kernel for large-scale structures and makes it difficult to directly import accurate diffraction loads calculated by external potential flow theory software.

[0007] This leads to a technical dilemma: on the one hand, engineers have the Morison formula (the first method) which is not accurate but is software compatible, and on the other hand, they have the three-dimensional potential flow theory (the second method) which is highly accurate, but their calculation results cannot be accepted and applied by conventional structural analysis procedures.

[0008] Therefore, when applying existing technologies to calculate hydrodynamic loads on large-diameter cylindrical structures, they face the "technology gap" and "compatibility" issues between high-precision calculation methods and standardized structural analysis software. There is a lack of a practical method that can utilize the accuracy of diffraction theory and seamlessly integrate into existing structural analysis processes. Summary of the Invention

[0009] To address the shortcomings of existing technologies, this invention provides a method for rapid correction of hydrodynamic loads on large-diameter cylindrical structures, solving the technical problem that existing methods for calculating hydrodynamic loads on large-diameter cylindrical structures cannot simultaneously achieve both calculation accuracy and efficiency.

[0010] To address the aforementioned technical problems, this invention provides a method for rapid correction of hydrodynamic loads on large-diameter cylindrical structures.

[0011] The technical solution adopted in this invention includes: First, this method establishes a database of correction coefficients. This process is applied to one or more preset load conditions: Calculate the total initial hydrodynamic load on the large-diameter cylindrical structure. In one embodiment, the total initial hydrodynamic load is calculated based on the Morison formula.

[0012] The total precise hydrodynamic load on the large-diameter cylindrical structure under the same load condition is calculated. In one embodiment, the total precise hydrodynamic load is calculated based on three-dimensional potential flow theory.

[0013] The calculation steps of this three-dimensional potential flow theory include: solving the Laplace equation and boundary conditions satisfied by the velocity potential in the fluid domain; applying the Bernoulli equation to calculate the dynamic water pressure distribution on the wetted surface of the structure caused by waves; and finally integrating the dynamic water pressure on the entire wetted surface of the structure to obtain the total accurate hydrodynamic load.

[0014] Based on the total initial hydrodynamic load and the total precise hydrodynamic load, the hydrodynamic load correction coefficient corresponding to the load condition is generated.

[0015] In one embodiment, the hydrodynamic load correction factor is generated by performing a ratio calculation between the total precise hydrodynamic load and the total initial hydrodynamic load.

[0016] The hydrodynamic load correction coefficient is correlated with the environmental parameters (such as wave period, wave height, etc.) that define the load condition, and stored in the database.

[0017] Secondly, when performing structural analysis on the large-diameter cylindrical structure, this method applies the correction coefficient database to perform rapid correction: For a given analysis condition, calculate the corresponding total initial hydrodynamic load. This calculation is also based on the Morison formula.

[0018] Obtain the hydrodynamic load correction coefficient corresponding to the given analysis condition.

[0019] In one implementation, if the given analysis condition is an intermediate condition not directly defined in the database, the acquisition step includes: retrieving neighboring condition data points from the database and calculating the condition using an interpolation method.

[0020] Based on the calculated total initial hydrodynamic load and the obtained hydrodynamic load correction coefficient, the corrected hydrodynamic load is calculated.

[0021] In one embodiment, the corrected hydrodynamic load is calculated by multiplying the total initial hydrodynamic load with the hydrodynamic load correction coefficient.

[0022] The modified hydrodynamic load is applied to the structural analysis model to replace the original total initial hydrodynamic load for subsequent structural stress or fatigue analysis.

[0023] In one implementation, a model generation step is included before performing the calculations in the database establishment phase: To adapt to the calculation of the total initial hydrodynamic load (based on the Morison formula), a discrete element model of the large-diameter cylindrical structure is generated; To adapt to the calculation of the total accurate hydrodynamic load (based on three-dimensional potential flow theory), a wetted surface mesh model of the large-diameter cylindrical structure is generated.

[0024] This invention provides a method for rapid correction of hydrodynamic loads on large-diameter cylindrical structures. It offers the following advantages: 1. This invention employs a total accurate hydrodynamic load calculated based on three-dimensional potential flow theory to correct the total initial hydrodynamic load calculated based on the Morison formula, generating a hydrodynamic load correction coefficient. This method ensures that the accuracy of the corrected hydrodynamic load finally applied to the structural analysis model is close to that calculated by three-dimensional potential flow theory, overcoming the deficiency of insufficient accuracy in calculating large-diameter cylindrical structures using the Morison formula alone.

[0025] 2. This invention solves the compatibility problem between high-precision algorithms and engineering software by using an offline database construction and online application approach. The invention pre-compiles complex three-dimensional potential flow theory calculations (for generating accurate loads) as an offline step, generating correction coefficients which are then stored in a database. In the online structural analysis application phase, engineers only need to execute the Morison formula calculation supported by the conventional structural analysis software and correct it using the correction coefficients of this invention (obtained through querying or interpolation) to obtain high-precision loads. This method requires no modification to existing structural analysis software, allowing high-precision diffraction loads to be applied in a compatible manner, significantly improving the accuracy of the analysis results while ensuring a smooth and efficient engineering analysis process.

[0026] 3. This invention links the correction coefficients with the environmental parameters of the defined load conditions and stores them in a database. It also uses interpolation to handle intermediate load conditions not directly defined in the database, making the correction method highly applicable. Once the offline database construction (creating a database for a specific structural form, water depth, etc.) is completed in one go, it can quickly respond to load correction requests for any given analysis condition, facilitating its widespread application in engineering practice. Attached Figure Description

[0027] Figure 1 This is a block diagram of the system functional modules of the present invention; Figure 2 This is a flowchart of the method of the present invention.

[0028] The module includes: 11. Structural model establishment module; 12. Initial load calculation module; 13. Precise load calculation module; 14. Correction coefficient generation and management module; 15. Load correction and application module; and 16. Data and process control module. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 are within the scope of protection of the present invention.

[0030] See attached document Figure 1 This invention provides a rapid correction system for hydrodynamic loads on a large-diameter cylindrical structure. The system is deployed on a computer device, which includes, but is not limited to, a processor, memory, and input / output interfaces. The rapid correction system for hydrodynamic loads on a large-diameter cylindrical structure includes: a structural model establishment module 11, an initial load calculation module 12, a precise load calculation module 13, a correction coefficient generation and management module 14, a load correction and application module 15, and a data and process control module 16.

[0031] The structural model building module 11 receives data on the geometric dimensions, material properties, and connection relationships of the hybrid structure of the jacket and the large-diameter cylinder, and generates a digital structural model for hydrodynamic analysis. This digital structural model contains all the geometric and physical information required for subsequent calculations.

[0032] The initial load calculation module 12, connected to the structural model establishment module 11, receives the digital structural model and environmental parameters under one or more specified load conditions. These environmental parameters include wave period and wave height. Based on the Morison formula and according to preset drag force and inertia force coefficients, this module calculates the initial hydrodynamic load on the large-diameter cylindrical structure under each specified load condition.

[0033] The precise load calculation module 13, which is also connected to the structural model establishment module 11, is used to calculate the diffraction hydrodynamic load on the large-diameter cylindrical structure based on three-dimensional potential flow theory under the same load conditions as those used in the initial load calculation module 12. The calculation results of this module are defined as the precise hydrodynamic load under this condition.

[0034] The correction coefficient generation and management module 14 is connected to both the initial load calculation module 12 and the precise load calculation module 13 to receive their calculation results. For each load condition, this module obtains the initial hydrodynamic load calculated by the initial load calculation module 12 and the precise hydrodynamic load calculated by the precise load calculation module 13. By calculating the ratio between the precise hydrodynamic load and the initial hydrodynamic load, it generates the hydrodynamic load correction coefficient corresponding to that load condition. This module also associates and stores the generated correction coefficients with the corresponding load condition parameters to form a correction coefficient database. Logically, this database can be a multi-dimensional data table, with index dimensions including key environmental parameters such as wave period, wave height, and water depth, while the stored values ​​are the corresponding correction coefficients. This structure facilitates rapid retrieval and multidimensional interpolation operations.

[0035] The load correction and application module 15 is connected to the initial load calculation module 12 and the correction coefficient generation and management module 14. In the process of analyzing the overall jacket structure, for a given load condition, this module first obtains the initial hydrodynamic load under that condition from the initial load calculation module 12. Then, it retrieves or interpolates the corresponding correction coefficients from the database maintained by the correction coefficient generation and management module 14. Finally, this module multiplies the initial hydrodynamic load by the correction coefficients to obtain the corrected hydrodynamic load, and applies this load as an external load input to the large-diameter cylindrical section of the overall jacket structure analysis model.

[0036] The data and process control module 16 coordinates the execution timing of other functional modules within the system and manages data flow between modules. The operational logic of the data and process control module 16 defines the process of establishing the correction coefficient database and the application process of structural analysis.

[0037] See attached document Figure 2This invention provides a method for rapidly correcting hydrodynamic loads on large-diameter cylindrical structures, which is implemented using a rapid correction system for hydrodynamic loads on large-diameter cylindrical structures.

[0038] Before performing hydrodynamic load correction calculations, it is necessary to first define the geometric parameters of the hybrid structure model and the environmental parameters on which the calculations are based.

[0039] The geometric parameters are received by the structural modeling module 11. These parameters characterize the geometric dimensions of the large-diameter cylindrical structure, primarily including its diameter. The geometric parameters may also include the spatial coordinates and dimensions of the various components of the jacket structure (such as legs and supports).

[0040] Environmental parameters are used to define one or more load conditions. These parameters are managed by the data and process control module 16 and provided to the initial load calculation module 12 and the precise load calculation module 13, respectively, according to the needs of the calculation process.

[0041] Environmental parameters include basic fluid parameters, such as the density of water. and operating water depth .

[0042] Environmental parameters also include parameters used to define specific wave conditions, such as wave period. and wave height A specific combination of wave parameters defines a working point for calculating the correction factor. .

[0043] Furthermore, the initial load calculation module 12 also needs to receive preset empirical coefficient values ​​during its calculation process based on the Morison formula. These coefficient values ​​specifically include the drag force coefficient. and inertial force coefficient .

[0044] The initial hydrodynamic load calculation is performed by the initial load calculation module 12. The initial load calculation module 12 is a functional unit used to perform the initial hydrodynamic load calculation for large-diameter cylindrical structures.

[0045] The initial load calculation module 12 is connected to the structural model establishment module 11 to receive the element model generated by it, which is discrete along the axis of the cylinder. The initial load calculation module 12 simultaneously receives one or more load conditions, which include environmental parameters such as water depth, wave period, and wave height.

[0046] The initial load calculation module 12 is internally configured with the calculation logic of the Morison formula. For each load condition, the initial load calculation module 12 first calculates the horizontal velocity of the undisturbed fluid at the center point of each discrete unit based on the selected wave theory and environmental parameters. and horizontal acceleration .

[0047] Subsequently, the initial load calculation module 12 calculates the load based on the preset drag force coefficient. and inertial force coefficient For each discrete element slice, calculate the horizontal hydrodynamic load per unit length. .

[0048] The initial load calculation module 12 calculates the unit length load. The total initial hydrodynamic load on the structure under this load condition is obtained by integrating along the entire wetted length of the large-diameter cylinder. .

[0049] The calculated total initial hydrodynamic load The values ​​are output to the correction factor generation and management module 14 for generating correction factors. Simultaneously, the initial load calculation module 12 is also invoked during the overall structural analysis to provide the load correction and application module 15 with the basic values ​​required for calculating the corrected loads.

[0050] The precise hydrodynamic load calculation is performed by the precise load calculation module 13. The precise load calculation module 13 is a functional unit used to calculate the precise hydrodynamic load of a large-diameter cylindrical structure, and its calculation results are defined as corrected standard values.

[0051] The precise load calculation module 13 is connected to the structural model building module 11 to receive the wet surface mesh model of the large-diameter cylindrical structure generated by the module, which is composed of surface elements.

[0052] The load condition parameters received by the precise load calculation module 13 are consistent with the load condition parameters used by the initial load calculation module 12 when calculating the initial hydrodynamic load.

[0053] The precise load calculation module 13 is internally configured with calculation logic based on three-dimensional potential flow theory. This theory, based on the ideal fluid assumption, is used to solve the diffraction problem when large-scale structures interact with waves.

[0054] During the calculation, the precise load calculation module 13 establishes and solves the Laplace equation satisfied by the velocity potential in the fluid domain, and simultaneously applies the seabed boundary condition, the linearized free surface boundary condition, and the impenetrable boundary condition of the structure surface.

[0055] In one implementation, the precise load calculation module 13 employs a numerical method, such as the boundary element method (also known as the surface element method) based on the Green's function method, to solve the aforementioned mathematical physics problem. Specifically, the constant surface element method can be used, where the velocity potential is assumed to be constant on each surface element, and the velocity potential value on each surface element is obtained by solving a system of integral equations.

[0056] After obtaining the velocity potential, the precise load calculation module 13 applies Bernoulli's equation to calculate the distribution of hydrodynamic pressure on the wetted surface of the structure caused by waves.

[0057] Finally, the precise load calculation module 13 integrates the calculated hydrodynamic pressure across the entire wetted surface of the structure to obtain the total precise hydrodynamic load acting on the large-diameter cylindrical structure under this load condition. .

[0058] After the calculation is completed, the total precise hydrodynamic load It is output to the correction factor generation and management module 14 to generate hydrodynamic load correction factors.

[0059] The correction coefficient generation and management module 14 is a functional unit used to generate, store and manage hydrodynamic load correction coefficients.

[0060] The data input terminal of the correction coefficient generation and management module 14 is connected to the data output terminals of the initial load calculation module 12 and the accurate load calculation module 13, respectively.

[0061] For any given load condition The correction coefficient generation and management module 14 receives the initial hydrodynamic load under this working condition from the initial load calculation module 12. And receive the precise hydrodynamic load under the same working condition from the precise load calculation module 13. .

[0062] The correction coefficient generation and management module 14 generates the hydrodynamic load correction coefficient corresponding to the load condition n by performing a ratio calculation on the two load values ​​mentioned above. .

[0063] The correction coefficient generation and management module 14 will calculate the correction coefficients. The data is associated with the environmental parameters (such as wave period, wave height, etc.) that define the working condition n, and the data unit is stored in the database.

[0064] By repeatedly performing the above steps on a series of load conditions covering a predetermined range, the correction factor generation and management module 14 establishes and maintains a correction factor database. This database is used to respond to query requests from the load correction and application module 15.

[0065] In one implementation, when the load correction and application module 15 requests a correction coefficient for an intermediate working condition that is not directly defined in the database, the correction coefficient generation and management module 14 can retrieve nearby working condition data points from the database and calculate the correction coefficient corresponding to the intermediate working condition using a multidimensional interpolation method. For example, if the correction coefficient is mainly related to the wave cycle... and wave height If the correlation is too high, bilinear interpolation or a smoother spline interpolation method can be used to obtain more accurate coefficient values.

[0066] In a more refined implementation, to improve correction accuracy, the initial load calculation module 12 and the precise load calculation module 13 respectively calculate and output the loads for multiple segments (e.g., divided by elevation) along the cylinder axis. The correction coefficient generation and management module 14 then generates the corresponding correction coefficient for each segment. ( (For section numbering). In application, the load correction and application module 15 assigns the initial load of each section to the corresponding correction factor. Multiply the results to obtain the corrected loads for each section, and apply them to the corresponding locations on the model. This method is particularly suitable for situations where the hydrodynamic loads are distributed very unevenly along the height of the structure.

[0067] Finally, the rapid correction and application of loads is performed by the load correction and application module 15. The load correction and application module 15 is a functional unit used to perform the final corrected load calculation and apply it to the overall structural analysis.

[0068] The data input terminal of the load correction and application module 15 is connected to the initial load calculation module 12 and the correction coefficient generation and management module 14, respectively.

[0069] In the process of performing overall structural analysis of the jacket, for a given load condition n, the load correction and application module 15 first obtains the initial hydrodynamic load under that condition from the initial load calculation module 12. .

[0070] Meanwhile, the load correction and application module 15 retrieves or obtains the hydrodynamic load correction coefficient corresponding to the working condition n from the database maintained by the correction coefficient generation and management module 14. .

[0071] Get and Then, the load correction and application module 15 performs a multiplication operation to calculate the corrected hydrodynamic load. .

[0072] The corrected hydrodynamic load The large-diameter cylindrical section applied to the overall structural analysis model of the jacket.

[0073] In a preferred application method, to achieve precise alignment with the structural analysis model (such as a finite element model), the load correction and application are not based on the total load, but rather on segmented loads. That is, the initial load calculation module 12 provides the load correction and application module 15 with the initial loads for each segment divided along the cylinder axis. ( (For section numbering). The load correction and application module 15 obtains the correction coefficients corresponding to each section from the correction coefficient generation and management module 14. (This coefficient is generated in segments during the database creation phase).

[0074] Subsequently, the load correction and application module 15 calculates the corrected load for each section. Ultimately, this set of corrective loads distributed along the axis... It is applied to the nodes of the corresponding section of the large-diameter cylinder in the structural analysis model, thereby achieving accurate correction of the spatial distribution of hydrodynamic loads.

[0075] Meanwhile, for the jacket section in the hybrid structure (typically composed of small-diameter components that meet the applicable conditions of the Morison formula), its hydrodynamic load is still calculated by the initial load calculation module 12 based on the Morison formula, and is directly applied to the corresponding components in the overall structural analysis model without correction. The corrected load of this invention... Together with the conventional Morison loads on the jacket section, they constitute the complete external hydrodynamic load input for the hybrid structure under current operating conditions.

[0076] This modified load replaces the original initial hydrodynamic load and serves as the external load input for subsequent structural stress analysis or fatigue analysis.

[0077] In one embodiment of the present invention, before modifying the hydrodynamic load of the large-diameter cylindrical structure, the hybrid structure model must first be established and parameterized through the structural model establishment module 11.

[0078] The structural model building module 11 is used to generate a digital hybrid structural model that geometrically accurately represents the solid dimensions, spatial positions, and interconnections of the jacket and the large-diameter cylinder. Input parameters include the diameter and height of the large-diameter cylinder, as well as the geometric parameters and layout information of the jacket components (such as pile legs, supports, and horizontal frames).

[0079] To accommodate the calculation requirements of the initial load calculation module 12, the structural model building module 11 parameterizes the large-diameter cylindrical structure into a series of discrete elements distributed along its central axis. Each element is assigned a defined diameter, length, and spatial coordinates to facilitate subsequent calculation and integration of the hydrodynamic loads on each element slice based on the Morison formula.

[0080] To meet the computational requirements of the precise load calculation module 13, the structural model building module 11 simultaneously meshes the wetted surface of the large-diameter cylindrical structure in contact with the fluid, generating a surface mesh model composed of multiple facets. This surface mesh model forms the geometric basis for performing three-dimensional potential flow theory diffraction calculations, and the size and distribution of the facets are set according to the computational accuracy requirements.

[0081] The structural model building module 11 ensures that the models generated by the two different calculation methods maintain consistency in core geometric parameters. To ensure the accuracy of subsequent piecewise corrections, the structural model building module 11 establishes a clear mapping relationship when generating the two models. Specifically, each element discretized along the axis (used for Morison formula calculations) corresponds spatially to one or more sets of surface elements on the wetted surface mesh model.

[0082] For example, a series of dividing planes along the cylinder axis (such as elevation Z) can be predefined. These planes define both the boundaries of the Morison computational elements and the boundaries of the corresponding surface element bands on the surface mesh. The structural model building module 11 will generate and store this index relationship between elements and surface element groups, ensuring that in the subsequent load correction and application module 15, the initial load calculated by the element along a specific axis can be accurately and piecewise corrected to the precise load obtained by integrating its corresponding surface element group.

[0083] For example, the cylinder diameter used in the Morison formula calculation is exactly the same as the cylinder diameter represented by the surface mesh model used in the three-dimensional potential flow theory calculation, thus ensuring the validity of the subsequently generated correction coefficients.

[0084] In one embodiment of the invention, the initial load calculation module 12 performs load calculations based on the Morison formula to obtain the initial hydrodynamic loads on the large-diameter cylindrical structure. This calculation forms the basis for subsequent correction processes.

[0085] The initial load calculation module 12 applies the Morison formula to each element slice discretized along the axis of the large-diameter cylinder, as defined by the structural model creation module 11. The horizontal hydrodynamic load acting on the cylinder per unit length consists of two parts: a drag force term and an inertial force term, expressed as follows: ; in, The horizontal force per unit length; The density of water; The diameter of the cylinder; and These represent the horizontal velocity and acceleration of the undisturbed fluid at the center point of the unit slice, respectively. This is the drag coefficient; This is the inertial force coefficient.

[0086] drag coefficient in the formula With inertial force coefficient This is an empirical coefficient. In specific implementation, its value is determined based on relevant marine engineering design specifications or recommended practices. For example, the initial load calculation module 12 can be configured to use... , The coefficient values ​​are calculated.

[0087] In one specific embodiment, the initial load calculation module 12 integrates one or more industry-recommended parameters. , The module provides functional relationship curves or lookup tables for Reynolds number and KC number. Before calculating the load on each discrete element, the module can automatically calculate the corresponding Reynolds number and KC number based on the element's diameter, water particle velocity, and acceleration amplitude, and then query or interpolate the most suitable values ​​for the current operating condition from the built-in database. and This allows for dynamic and automated selection of coefficients, improving the accuracy of initial load calculations.

[0088] velocity of fluid particles and acceleration The value is calculated by the initial load calculation module 12 based on the specified load condition parameters (such as wave height, period, and water depth) and the selected wave theory (such as linear wave theory, Stokes wave theory, etc.). This calculation is performed under the assumption that the cylindrical structure does not exist in order to obtain undisturbed flow field information.

[0089] The initial load calculation module 12 integrates the calculated unit length load along the entire wetted length of the large-diameter cylinder; this integration process is numerical integration. Specifically, the module divides the wetted portion of the large-diameter cylinder along the axis into... For each discrete element, calculate the center point of each element. Unit length load at the location Total initial hydrodynamic load This is obtained by summing the loads of all elements, i.e. ),in It is the first The length of each element. This discrete summation method is naturally compatible with the load application methods of structural analysis software such as the finite element method.

[0090] This yields the total initial hydrodynamic load acting on the entire large-diameter cylindrical structure under this load condition. This total load is output to the correction coefficient generation and management module 14 for subsequent correction coefficient generation.

[0091] In one embodiment of the present invention, the precise load calculation module 13 is used to calculate the precise hydrodynamic load on a large-diameter cylindrical structure under specified load conditions. The calculation results of the precise load calculation module 13 will serve as the benchmark for subsequent corrections.

[0092] The precise load calculation module 13 employs three-dimensional potential flow theory. This theory is based on the assumption of ideal fluid (i.e., inviscid, irrotational fluid) and is suitable for solving wave diffraction problems caused by large-scale structures. The core of the precise load calculation module 13 lies in solving the velocity potential function of the flow field.

[0093] In the calculation, the total velocity potential is decomposed into the sum of the incident wave velocity potential and the diffracted wave velocity potential. The incident wave velocity potential is determined by wave theory without structural disturbance. The diffracted wave velocity potential, on the other hand, characterizes the disturbance to the incident wave field caused by the presence of the structure.

[0094] The velocity potential function must satisfy the Laplace equation in the fluid domain. Simultaneously, appropriate boundary conditions must be applied during the solution process, including impenetrable boundary conditions on the seabed, linearized free surface boundary conditions (including dynamic and kinematic conditions), impenetrable boundary conditions on the wetted surface of the structure, and radiation conditions at infinity.

[0095] The precise load calculation module 13 employs a numerical method, such as the boundary element method (also known as the surface element method), to solve the aforementioned mathematical physics problem. This method utilizes the wetted surface mesh model of the large-diameter cylindrical structure generated by the structural model building module 11.

[0096] By solving the equations, the precise load calculation module 13 obtains the velocity potential distribution of each surface element on the wetted surface of the large-diameter cylindrical structure. Subsequently, the precise load calculation module 13 applies the linearized Bernoulli equation to calculate the hydrodynamic pressure distribution on each surface element based on the obtained velocity potential.

[0097] Finally, the precise load calculation module 13 integrates the hydrodynamic pressure on all surface elements across the entire wetted surface of the structure to obtain the total wave force acting on the large-diameter cylindrical structure. This total wave force is defined as the precise hydrodynamic load under the current load condition.

[0098] After the calculation is completed, the accurate load calculation module 13 outputs the result of the accurate hydrodynamic load to the correction coefficient generation and management module 14 for comparison with the initial hydrodynamic load to generate correction coefficients.

[0099] In one embodiment of the present invention, the correction coefficient generation and management module 14 is responsible for generating and managing the correction coefficients. The correction coefficient generation and management module 14 is connected to the data output terminals of the initial load calculation module 12 and the accurate load calculation module 13.

[0100] For each specific load condition defined by environmental parameters (e.g., numbered...), (For the working condition), the correction coefficient generation and management module 14 obtains the initial hydrodynamic load under this working condition from the initial load calculation module 12. And obtain the precise hydrodynamic load under the same working condition from the precise load calculation module 13. .

[0101] After acquiring the two load data, the correction coefficient generation and management module 14 determines the hydrodynamic load correction coefficient corresponding to the working condition n through ratio calculation. The calculation formula is as follows: ; In a preferred embodiment of the present invention, the initial hydrodynamic load and precise hydrodynamic loads It is not a single numerical value, but a set of loads containing multiple key mechanical components. This set of loads includes at least the total horizontal shear force (in the direction of wave propagation) and the overturning moment (at the structural base), which are crucial to the overall stability of the structure.

[0102] Therefore, the hydrodynamic load correction factor It is not a single scalar, but a set of correction coefficients corresponding to the load components. The correction coefficient generation and management module 14 will perform ratio calculations on each mechanical component to generate independent correction coefficients. For example: Shear force correction factor ; Torque correction factor ; in, and The total horizontal shear force is obtained from precise calculation and initial calculation, respectively; and The overturning moments are obtained from precise calculation and initial calculation, respectively.

[0103] The correction coefficient generation and management module 14 will generate and manage this set of correction coefficients (such as...) , ) and the definition of this working condition The environmental parameters are correlated and stored in the database. When applied to structural analysis, the corresponding correction coefficients will be invoked according to the analysis requirements (e.g., checking base shear or checking overturning stability).

[0104] During the establishment of the correction coefficient database, the data and process control module 16 will first receive a user-defined predetermined range of environmental parameters covering the target sea area. This range is determined, for example, based on environmental contour lines or wave scattering maps of the target sea area, such as wave periods. Scope and wave height Scope Subsequently, the data and process control module 16 executes the data according to a preset step size (e.g., cycle step size). Wave height step length Within this range, a series of discrete load condition points are automatically generated. The data and process control module 16 will automatically coordinate and batch call the initial load calculation module 12 and the precise load calculation module 13 to perform calculations for each condition point in the series, and then hand the results over to the correction coefficient generation and management module 14 to generate and store the corresponding correction coefficients. This continues until the entire predetermined range is covered, thus completing the offline establishment of the correction coefficient database.

[0105] The correction coefficient generation and management module 14 will calculate the correction coefficients. With definition of this working condition The environmental parameters (such as wave period, wave height, etc.) are correlated, and the data is stored in the memory.

[0106] By repeatedly performing the above steps on a series of load conditions covering a predetermined range, the correction factor generation and management module 14 establishes and maintains a correction factor database. This database is used to provide a fast query service to the load correction and application module 15.

[0107] In one implementation, when the load correction and application module 15 requests a correction coefficient for a working condition (i.e., an intermediate working condition) that is not directly defined in the database, the correction coefficient generation and management module 14 can retrieve several data points from the database that are closest to the working condition, and calculate the correction coefficient for the intermediate working condition using an interpolation method. The interpolation method includes, but is not limited to, linear interpolation or spline interpolation.

[0108] In a more advanced implementation, to more accurately describe the effect of diffraction on the dynamic characteristics of the load, both the initial hydrodynamic load and the precise hydrodynamic load can be expressed as complex numbers containing amplitude and phase information. Under the assumption of linear wave theory, periodic loads... It can be represented as ,in For complex load amplitude.

[0109] In this case, the initial load calculation module 12 and the precise load calculation module 13 respectively output complex loads. and The correction coefficients calculated by the correction coefficient generation and management module 14 It will also be a plural number: ; The complex correction coefficient The modulus represents the correction ratio of the amplitude, while its argument represents the phase shift caused by the diffraction effect.

[0110] To further illustrate the embodiments of the present invention, an example of hydrodynamic load correction under a specific working condition is given below.

[0111] First, a hybrid structural model is defined using module 11, which establishes the structural model. The hybrid structural model is located at a specific water depth. Meters. The large-diameter cylindrical structure in the model is a vertical cylinder with a diameter of... Meters. Simultaneously define a specific load case to be analyzed. The wave cycle of this operating condition seconds, wave height Meters. Setting the density of water. kg / m 3 .

[0112] Next, the initial load calculation module 12 is invoked. The drag force coefficient is set. Inertial force coefficient The initial load calculation module 12 calculates the flow field based on the above working parameters and using linear wave theory. Then, it integrates the flow field using the Morison formula to obtain the total initial hydrodynamic load of the large-diameter cylindrical structure under this working condition. Assume the result of this calculation is N.

[0113] Then, the precise load calculation module 13 is invoked. The precise load calculation module 13 is used for the same working condition ( (seconds), using the boundary element method based on three-dimensional potential flow theory, diffraction calculations are performed on the wetted surface mesh model generated by the structural model building module 11. It is assumed that the total accurate hydrodynamic load obtained from this calculation is... N.

[0114] Subsequently, the correction coefficient generation and management module 14 is invoked. The correction coefficient generation and management module 14 receives the two calculation results mentioned above and performs a ratio calculation to generate the correction coefficient. : ; The correction coefficient generation and management module 14 will generate and manage the correction coefficient. With operating parameters ( (seconds) are associated and stored in the correction coefficient database.

[0115] Finally, during the overall structural analysis of the hybrid structure of the jacket and the large-diameter cylinder, the load correction and application module 15 was invoked. When the analysis condition is... At the specified time, the load correction and application module 15 first obtains the load from the initial load calculation module 12. And retrieve the corresponding correction coefficient from the database of the correction coefficient generation and management module 14. .

[0116] Load Correction and Application Module 15 calculates the corrected hydrodynamic loads. : ; The corrected load The large-diameter cylindrical section is applied to the overall structural analysis model of the jacket to replace the original Morison load for subsequent structural stress or fatigue analysis.

Claims

1. A method for rapidly correcting hydrodynamic loads of a large-diameter cylindrical structure, characterized by, The method comprises the following steps: S1, calculating total initial hydrodynamic load of the large-diameter cylindrical structure; S2, calculating total accurate hydrodynamic load of the large-diameter cylindrical structure under the same load condition; S3, generating a hydrodynamic load correction coefficient corresponding to the load condition based on the total initial hydrodynamic load and the total accurate hydrodynamic load; S4, calculating total initial hydrodynamic load corresponding to a given analysis condition; S5, obtaining a hydrodynamic load correction coefficient corresponding to the given analysis condition; S6, calculating a corrected hydrodynamic load based on the total initial hydrodynamic load calculated in step S4 and the hydrodynamic load correction coefficient obtained in step S5; S7, applying the corrected hydrodynamic load to a structural analysis model.

2. The method according to claim 1, wherein In the S1 step, the total initial hydrodynamic load is calculated based on the Morison formula.

3. The method according to claim 1, wherein In the S2 step, the total accurate hydrodynamic load is calculated based on three-dimensional potential flow theory.

4. The method of claim 1, wherein In the S3 step, the hydrodynamic load correction coefficient is generated by performing a ratio operation on the total accurate hydrodynamic load and the total initial hydrodynamic load.

5. The method of claim 1, wherein In the S6 step, the corrected hydrodynamic load is calculated by performing a multiplication operation on the total initial hydrodynamic load and the hydrodynamic load correction coefficient.

6. The method of claim 1, wherein Before the S1 step, the following steps are further included: To adapt to the calculation of the total initial hydrodynamic load, a discrete element model of the large-diameter cylindrical structure is generated; To adapt to the calculation of the total accurate hydrodynamic load, a wet surface grid model of the large-diameter cylindrical structure is generated.

7. The method of claim 1, wherein Further included are: Data association of the hydrodynamic load correction coefficient with environmental parameters defining the load condition is performed, and the data is stored in a database.

8. The method according to claim 7, wherein In the S5 step, if the given analysis condition is an intermediate condition not directly defined in the database, the step of obtaining the hydrodynamic load correction coefficient comprises: Retrieving adjacent condition data points from the database and calculating the hydrodynamic load correction coefficient using an interpolation method.

9. The method of claim 2, wherein The total initial hydrodynamic load is obtained by integrating the horizontal hydrodynamic load per unit length along the wetted length of the large-diameter cylinder, and the horizontal hydrodynamic load per unit length is calculated based on the density of water, the diameter of the cylinder, the horizontal velocity, the horizontal acceleration, the drag force coefficient and the inertia force coefficient.

10. The method of claim 3, wherein The S2 step comprises: Solving Laplace equation and boundary conditions satisfied by velocity potential in the fluid domain; Applying Bernoulli equation to calculate the dynamic water pressure distribution on the wet surface of the structure caused by waves; Integrating the dynamic water pressure over the entire wet surface of the structure to obtain the total accurate hydrodynamic load.

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