CN-122020964-A - Frequency domain calculation method for dynamic response of multi-body flexible connection floating fan

CN122020964ACN 122020964 ACN122020964 ACN 122020964ACN-122020964-A

Abstract

The invention discloses a frequency domain calculation method of dynamic response of a multi-body flexible connection floating fan, and solving a frequency domain motion equation of the floating fan by establishing and combining a hydrodynamic coefficient matrix, a linearized pneumatic load, a viscous drag load, a mooring load and a stiffness matrix of the flexible rope. The dynamic response of the multi-body flexible connection floating fan can be rapidly calculated in the frequency domain range, and the calculation efficiency of the type-selecting design stage of the floating fan is greatly improved. The constraint force of the flexible connecting rope on the upper and lower modules of the floating foundation is linearized into a rigidity matrix, so that the internal force of the flexible connecting piece is conveniently analyzed in the initial stage of structural design, and a guarantee is provided for structural safety design of the floating fan of the type.

Inventors

CHEN JIANDONG
WANG KUN
Yi Wenhai
FAN YUANCHENG
Nishina Kei
JIANG TIAN

Assignees

中国电建集团贵州工程有限公司

Dates

Publication Date: 20260512
Application Date: 20251225

Claims (10)

1. The frequency domain calculation method for the dynamic response of the multi-body flexible connection floating fan is characterized by comprising the following 4 steps: S1, dividing a floating body module, establishing a wet surface model, and calculating a floating foundation hydrodynamic coefficient matrix; S2, carrying out linearization treatment on nonlinear load in the floating fan system to obtain linearization load, wherein the linearization load comprises pneumatic load, viscous drag force load and mooring load; s3, calculating a flexible rope stiffness matrix of the flexible rope of the floating foundation connection section to the floating body module; And S4, solving a frequency domain motion equation of the floating fan by combining the hydrodynamic coefficient matrix, the linearization load and the flexible rope stiffness matrix.
2. The method for calculating the dynamic response frequency domain of the multi-body flexible connection floating fan according to claim 1, wherein the floating body module and the wet surface model are divided into two rigid body modules in the step S1, wherein the fan tower and the upper layer float of the floating foundation are divided into one rigid body module, the weight hung on the lower layer is separately divided into one rigid body module, and the two modules are connected through a plurality of flexible ropes. The hydrodynamic coefficient matrix comprises an additional mass matrix of two rigid body modules with 12 degrees of freedom Radiation damping matrix Matrix for recovering rigidity by still water First order wave excitation force transfer function matrix 。
3. The frequency domain calculation method of dynamic response of the multi-body flexible connection floating fan as claimed in claim 1, wherein the linearization calculation formula of the pneumatic load is: In the formula, In response to aerodynamic force terms for floating foundation structure movements, For aerodynamic items independent of floating foundation movement, by simulating the aerodynamic load time course of a fixed fan in a turbulent wind field with given average wind speed and converting the aerodynamic load time course into a frequency domain, Is a coefficient of pneumatic inertia, and is a coefficient of pneumatic inertia, Is the coefficient of the pneumatic damping, Is the excitation frequency.
4. The frequency domain computing method of dynamic response of the multi-body flexible connection floating fan as claimed in claim 3, wherein the pneumatic inertia coefficient Pneumatic damping coefficient The calculation formula of (2) is as follows: In the formula, And Proportional integral gain of the control system respectively; the generator low-speed shaft inertia moment is obtained; , , , , , the pneumatic thrust T and the pneumatic torque Q are respectively related to the relative wind speed v and the rotating speed of the fan Pitch angle of blade Is used for the partial derivative of (a), Is a transfer function of the coupling of the pneumatic load to the movement of the structure.
5. The frequency domain computing method of the dynamic response of the multi-body flexible connection floating fan of claim 1, wherein the viscous drag load linearization is represented by a viscous damping matrix: , In the formula, To act on the total viscous drag load on the floating foundation, The motion speed of the floating fan is the motion speed of the floating fan; Viscous damping matrix The calculation formula is as follows: , in the formula (6), the amino acid sequence of the compound, In order to achieve a fluid density, As a coefficient of drag force of the unit, Is the diameter of the cylinder of the unit, The root mean square value of the movement speed of the unit is represented by k, the index of dividing the unit is represented by 1,2, 3, 7, 8 and 9, and the index of degree of freedom is represented by the index; For the unit transformation matrix, the calculation formula is as follows: , In the formula, Is the kth cell center point position coordinate.
6. The frequency domain computing method of dynamic response of a multi-body flexible connection floating fan according to claim 1, wherein the mooring load is normalized to a stiffness matrix by using a quasi-static normal: , In the formula, For mooring the load at the pilot hole, Is a mooring system stiffness matrix.
7. The frequency domain calculating method of dynamic response of a multi-body flexible connection floating fan according to claim 1, wherein the stiffness matrix building step of the flexible rope of the floating foundation connection section is as follows: S31, combining floating foundation movement to obtain a position coordinate calculation formula of two end points of the single flexible rope: , , In the formula, Six degree of freedom motion response for a single module; Is a transformation matrix for transforming local coordinates into global coordinates; Is the global coordinate of the connection point, The subscript a represents the label of the flexible connecting piece, and subscripts 1 and 2 represent the labels of the module 1 and the module 2 respectively; S32, regarding the connecting piece a as rigidity Original length Calculating the tension of the single connection according to hooke's law: In the formula, In order to connect the current position vector of the rope, ; Is a unit vector of the rope, ; S3, obtaining the constraint force of a single connecting rope a on the modules 1 and 2, and summing the constraint forces of all connecting ropes to obtain the constraint load of m connecting pieces on the floating foundation : , , , In the balanced position Performing first-order Talyor expansion, neglecting more than second-order terms, and extracting the rigidity matrix of the connecting piece from the intermediate granules : 。
8. The frequency domain computing method of the dynamic response of the multi-body flexible connection floating fan as claimed in claim 1, wherein the frequency domain motion equation is: , in the upper left end of the tube, Is the mass inertia matrix of the floating fan, For the purpose of the additional mass matrix, In the form of a pneumatic inertial matrix, In order to radiate the damping matrix, In the form of a pneumatic inertial matrix, Is a pneumatic damping matrix, which is composed of a plurality of damping arrays, For the still water to recover the stiffness matrix, The load of the connecting piece is applied to the connecting piece, In order to moor the load, Responding aerodynamic force items for floating foundation structure movement; For aerodynamic items independent of floating foundation motion, Is a first order wave force transfer function; Is wave height.
9. The frequency domain computing method of dynamic response of the multi-body flexible connection floating fan as claimed in claim 7, wherein the wave height According to wave spectrum And adding random phase Expressed as complex: 。
10. The frequency domain calculation method of the dynamic response of the multi-body flexible connection floating fan according to claim 7, wherein the solving result of the frequency domain motion equation further comprises a flexible connection piece tension response, and the flexible rope tension response calculation formula is: , , In the middle of For the restraining load of the ith flexible cord, For the ith connector stiffness matrix, For the tension level of the ith flexible cord, The first 3 degrees of freedom of the translational components of the load are constrained for the ith flexible rope.

Description

Frequency domain calculation method for dynamic response of multi-body flexible connection floating fan Technical Field The invention relates to a frequency domain calculation method for dynamic response of a multi-body flexible connection floating fan. Background In order to cope with the energy crisis and develop clean energy, the global offshore wind power has come to be in a rapid development period in recent years. It is estimated that 80% of offshore wind energy resources are located in deep sea areas with water depths exceeding 60m, and that an increase in water depths results in a stationary wind turbine no longer being economically viable, floating wind power being the dominant technology for deep sea wind energy resource development. The single floating fan mainly comprises a wind power generation system, a supporting tower, a floating foundation and a mooring system, wherein the floating foundation is mainly used for providing restoring force for the whole system and can be roughly divided into four types of single column type, tension leg type, semi-submersible type and barge type according to the mode of acquiring stability. With the trend of "large-scale and innovative" development of floating wind power, flexible connection is introduced into the design of a floating foundation to realize the coupling of a plurality of modules, such as a wind energy and wave energy hybrid power generation device, a Spar type floating fan with a suspended counterweight and the like. The flexible connecting piece belongs to a weak component, complex alternating load is generated in the running process of the floating fan, fatigue and even strength damage are easy to occur, and the structural safety is threatened, so that the dynamic behavior of the flexible component needs to be focused on for the research of the fan, and the structural safety is ensured. The floating wind turbine is subjected to a large number of dynamic response calculations at the beginning of the design to determine the proper basic structure shape, and alternative numerical calculation methods include a time domain method and a frequency domain method. The time domain method belongs to a simulation method of pneumatic-hydrodynamic-elastic-control coupling, has relatively high accuracy but low calculation speed, and has lower calculation efficiency in a design selection stage of the floating fan. The frequency domain rule is to directly solve the frequency domain motion equation to obtain the steady-state response of the structure under different frequencies, the calculation speed is far higher than that of the time domain method, and the occupied memory is less, so that the frequency domain method is more suitable for the earlier design and selection of the floating fan. However, most of the existing floating fan frequency domain calculation methods consider the foundation part as a single rigid body, and flexible components in the floating foundation are rarely considered, so that the application range of the floating fan frequency domain calculation method is limited to a certain extent. Disclosure of Invention Aiming at the problems that the foundation part is mostly regarded as a single rigid body and flexible components in the floating foundation are hardly considered in the frequency domain calculation method of the floating fan, the invention provides the frequency domain calculation method of the dynamic response of the multi-body flexible connection floating fan, which can rapidly solve the internal force of a flexible rope in the frequency domain range and forecast the dynamic response of the floating fan. The technical scheme of the invention is as follows: a frequency domain calculation method for dynamic response of a multi-body flexible connection floating fan comprises the following steps: S1, dividing a floating body module, establishing a wet surface model, and calculating a floating foundation hydrodynamic coefficient matrix; S2, carrying out linearization treatment on nonlinear load in the floating fan system to obtain linearization load, wherein the linearization load comprises pneumatic load, viscous drag force load and mooring load; s3, calculating a flexible rope stiffness matrix of the flexible rope of the floating foundation connection section to the floating body module; And S4, solving a frequency domain motion equation of the floating fan by combining the hydrodynamic coefficient matrix, the linearization load and the flexible rope stiffness matrix. The step S1 is to divide the floating fan into two rigid body modules, wherein the fan tower and the upper layer float of the floating foundation are divided into one rigid body module, the counterweight hung on the lower layer is divided into one rigid body module, and the two modules are connected through a plurality of flexible ropes. The hydrodynamic coefficient matrix comprises an additional mass matrix of two rigid body modulesRadiation damping matrixMatrix for