A method and system for transferring motion energy of large ships in wind, wave and current environment

Abstract

The present invention provides a method and system for transferring energy from the motion of a large ship in a wind-wave and current environment. A first fluctuating wind speed model is established based on the characteristic parameters of the sea breeze, waves and ships under different sea conditions, and a specific calculation method is used to calculate the power spectrum density of the fluctuating wind speed, and a relationship between the power spectrum density and amplitude of the fluctuating wind speed is constructed within the angular frequency range; then a second fluctuating wind speed model is obtained through the relationship and the first fluctuating wind speed model, and the absolute wind speed of the sea breeze is calculated; finally, based on the time domain motion signal and the absolute wind speed under any ocean environment, a specific calculation method is used to calculate the average power of the waves, sea breeze and ship respectively, and then the energy transfer efficiency of the disturbed motion of the ship under different sea conditions is calculated. By fully considering the working environment under the joint influence of the complex wind-wave and current environment under different sea conditions, the motion characteristics and energy transfer relationship of the large ship under different working conditions can be comprehensively described.

Description

Technical Field

[0001] The present invention relates to the technical field of ship engineering and ocean engineering, and in particular to a method and system for transmitting motion energy of a large ship in a wind, wave and current environment. Background Art

[0002] With the rapid development of the ocean transportation industry, research into the motion behavior and energy transfer mechanisms of large ships in complex ocean environments has become increasingly crucial. Ships' navigation at sea is not only influenced by natural factors such as waves, winds, and currents, but these factors also determine the ship's stability in varying sea conditions. For large ships in particular, accurately understanding and predicting their motion characteristics in adverse sea conditions is crucial for ensuring safe navigation.

[0003] Traditional ship motion analysis methods primarily focus on calculating static and dynamic responses. When analyzing a ship's disturbed motion, these methods often fail to fully consider the interactions between wind, waves, and currents, as well as the impact of wave distribution in wind-wave and current environments on energy transfer efficiency. Instead, they typically evaluate a ship's performance under specific sea conditions by analyzing individual motion modes, such as heave, roll, and pitch. Consequently, these methods still have certain limitations when dealing with complex sea conditions and cannot fully reveal the impact of energy transfer efficiency on a ship's motion characteristics. Summary of the Invention

[0004] The present invention addresses the problems that exist in the current research on the motion behavior of large ships in complex marine environments and their energy transfer mechanisms, such as the failure to consider the interaction between sea breeze, waves, and currents, and the inability to fully reveal the impact of energy transfer efficiency on the ship's motion characteristics. A method for energy transfer of large ship motion in a wind-wave-current environment is provided. Based on the characteristic parameters of sea breeze, wave characteristics, and the motion state parameters of the ship under different sea conditions, a pulsating wind speed model is constructed using a specific calculation method to calculate the absolute wind speed, and then the energy transfer efficiency of the disturbed motion of the ship under different sea conditions is calculated. By fully considering the mutual influence and action between sea breeze, waves, and currents under different sea conditions, the motion amplitude of the ship in complex sea conditions can be effectively reduced, which is of great significance for understanding and responding to complex marine environments. The present invention also relates to an energy transfer system for large ship motion in a wind-wave-current environment.

[0005] The technical solutions of the present invention are as follows:

[0006] A method for transferring motion energy of a large ship in a wind-wave and current environment, characterized by comprising the following steps:

[0007] Parameter acquisition step: acquiring time domain motion signals under different ocean environments, as well as sea breeze characteristic parameters, wave characteristic parameters and ship motion state parameters under different sea conditions, wherein the sea breeze characteristic parameters include the circular frequency of the fluctuating wind speed, the average wind speed at sea level, the correlation length of the wind speed fluctuation, and the amplitude, angular frequency and initial phase of each simple harmonic wave of the fluctuating wind speed; the wave characteristic parameters include the circular frequency, amplitude, wave number, wave height and unit width of the wave; and the ship motion state parameters include the volume, speed and mass of the ship;

[0008] Power spectrum density calculation steps: Calculate the average value of the circular frequency of the fluctuating wind speed based on the circular frequency of the fluctuating wind speed, the average wind speed at sea level, and the correlation length of the wind speed fluctuations, and calculate the power spectrum density of the fluctuating wind speed based on the average value of the circular frequency of the fluctuating wind speed, the average wind speed at sea level, and the correlation length of the wind speed fluctuations;

[0009] The first fluctuating wind speed model and relationship establishment step includes: establishing the first fluctuating wind speed model based on the amplitude, angular frequency, and initial phase of each simple harmonic wave of the fluctuating wind speed; establishing an angular frequency interval based on the angular frequency and a frequency bandwidth set based on the angular frequency; and constructing a relationship between the power spectral density and the amplitude of the fluctuating wind speed when the angular frequency is within the angular frequency interval;

[0010] Calculation steps for fluctuating wind speed and absolute wind speed: Based on the relationship between the power spectrum density and amplitude of the fluctuating wind speed and the first fluctuating wind speed model, a second fluctuating wind speed model is obtained to further calculate the fluctuating wind speed; the absolute wind speed of the sea breeze is calculated based on the fluctuating wind speed and the average wind speed at sea level;

[0011] The steps of establishing the average signal power model are as follows: a first average signal power model is established based on the time domain motion signal and simulation time in any ocean environment, and the time domain motion signal is converted into a frequency domain motion signal by Fourier transform, and then the Parsval energy equation for the energy of the time domain motion signal and the energy of the frequency domain motion signal is obtained according to the Parsval theorem; a second average signal power model is obtained according to the first average signal power model and the Parsval energy equation, and an expression for the power spectrum density of the frequency domain motion signal is recursively obtained based on the second average signal power model, and a third average signal power model is then recursively obtained based on the second average signal power model and the expression for the power density of the frequency domain motion signal;

[0012] The steps for calculating the average power and energy transfer efficiency are as follows: a wave energy model is established based on the wave height and the unit width of the waves, and the average power of the waves is calculated based on the wave energy model and the third average signal power model; a disturbed sea breeze energy model is established based on the absolute wind speed and air density, and the average power of the sea breeze is calculated based on the disturbed sea breeze energy model and the third average signal power model; a ship energy model is then established based on the mass, volume and speed of the ship, and the average power of the ship is calculated based on the ship energy model and the third average signal power model; the energy transfer efficiency of the disturbed motion of the ship under different sea conditions is calculated based on the average power of the ship, the average power of the waves and the average power of the sea breeze.

[0013] Preferably, in the step of establishing the first pulsating wind speed model and the relationship, establishing the angular frequency interval according to the angular frequency and the bandwidth set based on the angular frequency includes: using the frequency equal division method to divide the wave spectrum frequency range under multiple different sea conditions into multiple parts, and setting the length of each part as the bandwidth, and establishing the angular frequency interval of each wave spectrum frequency according to the angular frequency and the bandwidth.

[0014] Preferably, in the parameter acquisition step, the time domain motion signals under different ocean environments include the time domain motion signals of sea breeze, the time domain motion signals of waves and the time domain motion signals of ocean currents; the wave characteristic parameters also include wavelength, and the wave number is calculated based on the wavelength.

[0015] Preferably, in the parameter acquisition step, when obtaining the correlation length of wind speed fluctuations, the correlation length of wind speed fluctuations is obtained by performing statistical analysis on wind speed data at multiple different time points to improve the adaptability of the model to wind speed changes on different time scales.

[0016] A large ship motion energy transfer system in a wind-wave and current environment, characterized by comprising a parameter acquisition module, a power spectrum density calculation module, a first fluctuating wind speed model and relationship establishment module, a fluctuating wind speed and absolute wind speed calculation module, an average signal power model establishment module, and an average power and energy transfer efficiency calculation module, which are connected in sequence.

[0017] The parameter acquisition module acquires time domain motion signals under different ocean environments, as well as sea breeze characteristic parameters, wave characteristic parameters and ship motion state parameters under different sea conditions. The sea breeze characteristic parameters include the circular frequency of the fluctuating wind speed, the average wind speed at sea level, the correlation length of the wind speed fluctuation, and the amplitude, angular frequency and initial phase of each simple harmonic wave of the fluctuating wind speed; the wave characteristic parameters include the circular frequency, amplitude, wave number, wave height and unit width of the wave; the ship motion state parameters include the volume, speed and mass of the ship;

[0018] The power spectrum density calculation module calculates the average value of the circular frequency of the fluctuating wind speed according to the circular frequency of the fluctuating wind speed, the average wind speed at sea level, and the correlation length of the wind speed fluctuation, and calculates the power spectrum density of the fluctuating wind speed according to the average value of the circular frequency of the fluctuating wind speed, the average wind speed at sea level, and the correlation length of the wind speed fluctuation;

[0019] The first fluctuating wind speed model and relationship establishment module establishes the first fluctuating wind speed model based on the amplitude, angular frequency, and initial phase of each simple harmonic wave of the fluctuating wind speed; establishes an angular frequency interval based on the angular frequency and a bandwidth set based on the angular frequency, and constructs a relationship between the power spectrum density and the amplitude of the fluctuating wind speed when the angular frequency is within the angular frequency interval;

[0020] The fluctuating wind speed and absolute wind speed calculation module obtains a second fluctuating wind speed model based on the relationship between the power spectrum density and amplitude of the fluctuating wind speed and the first fluctuating wind speed model, and then calculates the fluctuating wind speed; and calculates the absolute wind speed of the sea breeze based on the fluctuating wind speed and the average wind speed at sea level;

[0021] The average signal power model establishment module establishes a first average signal power model based on the time domain motion signal and simulation time in any ocean environment, and uses Fourier transform to convert the time domain motion signal into a frequency domain motion signal, and then obtains the Parsval energy equation for the energy of the time domain and frequency domain motion signals according to the Parsval theorem; obtains a second average signal power model based on the first average signal power model and the Parsval energy equation, and recursively obtains an expression for the power spectrum density of the frequency domain motion signal based on the second average signal power model, and then recursively obtains a third average signal power model based on the second average signal power model and the expression for the power density of the frequency domain motion signal;

[0022] The average power and energy transfer efficiency calculation module establishes a wave energy model based on the wave height and the unit width of the waves, and calculates the average power of the waves according to the wave energy model and the third average signal power model; establishes a disturbed sea breeze energy model based on the absolute wind speed and air density, and calculates the average power of the sea breeze according to the disturbed sea breeze energy model and the third average signal power model; then establishes a ship energy model based on the mass, volume and speed of the ship, and calculates the average power of the ship according to the ship energy model and the third average signal power model; and calculates the energy transfer efficiency of the disturbed motion of the ship under different sea conditions according to the average power of the ship, the average power of the waves and the average power of the sea breeze.

[0023] Preferably, in the first pulsating wind speed model and relationship establishment module, establishing the angular frequency interval according to the angular frequency and the bandwidth set based on the angular frequency includes: using the frequency equal division method to divide the wave spectrum frequency range under multiple different sea conditions into multiple parts, and setting the length of each part as the bandwidth, and establishing the angular frequency interval of each wave spectrum frequency according to the angular frequency and the bandwidth.

[0024] Preferably, the time domain motion signals under different ocean environments include the time domain motion signals of sea breeze, the time domain motion signals of ocean waves and the time domain motion signals of ocean currents; the ocean wave characteristic parameters also include wavelength, and the wave number is calculated based on the wavelength.

[0025] Preferably, in the parameter acquisition module, when obtaining the correlation length of wind speed fluctuation, the correlation length of wind speed fluctuation is obtained by statistically analyzing the wind speed data at multiple different time points, so as to improve the adaptability of the model to wind speed changes on different time scales.

[0026] The beneficial effects of the present invention are:

[0027] The present invention provides a method for transferring energy from the motion of a large ship in a wind-wave and current environment. The method is based on the characteristic parameters of sea breeze and waves under different sea conditions and adopts a specific calculation method to calculate the power spectrum density of the fluctuating wind speed, which can effectively reveal the energy distribution of wind speed fluctuations; then, a first fluctuating wind speed model is established based on the amplitude, angular frequency and initial phase of each simple harmonic wave of the fluctuating wind speed, which can more finely describe the random variation characteristics of the wind speed, capture the details of the wind speed variation, and improve the authenticity and reliability of the model; and an angular frequency interval is established according to the angular frequency and the bandwidth set based on the angular frequency. When the angular frequency is within the angular frequency interval, a relationship between the power spectrum density and the amplitude of the fluctuating wind speed is constructed, which can better identify the different frequencies. The contribution of the frequency component to the total wind speed is helpful to identify the main source of disturbance, thereby optimizing the prediction model and intuitively displaying the energy distribution of different frequency components. Finally, based on the time domain motion signal and absolute wind speed in any ocean environment, a specific calculation method is used to calculate the average power of waves, sea breeze and ships respectively, and then the energy transfer efficiency of the disturbed motion of the ship under different sea conditions is calculated. By fully considering the working environment of the complex wind, wave and current environment under different sea conditions, the motion characteristics and energy transfer relationship of the heave, roll and pitch of large ships in different working conditions can be more comprehensively described, which can effectively reduce the motion amplitude of the ship in complex sea conditions, which is of great significance for understanding and responding to complex ocean environments.

[0028] The present invention also relates to a large ship motion energy transfer system in a wind, wave and current environment. The system corresponds to the above-mentioned large ship motion energy transfer method in a wind, wave and current environment, and can be understood as a system that implements the above-mentioned large ship motion energy transfer method in a wind, wave and current environment, including a parameter acquisition module, a power spectrum density calculation module, a first fluctuating wind speed model and relationship establishment module, a fluctuating wind speed and absolute wind speed calculation module, an average signal power model establishment module and an average power and energy transfer efficiency calculation module connected in sequence. The modules cooperate with each other, based on the sea breeze characteristic parameters, wave characteristic parameters and motion state parameters of the ship under different sea conditions, and adopt a specific calculation method to construct a fluctuating wind speed model to calculate the absolute wind speed, and then calculate the energy transfer efficiency of the disturbed motion of the ship under different sea conditions. By fully considering the mutual influence and action between the sea breeze, waves and currents under different sea conditions, the motion amplitude of the ship in complex sea conditions can be effectively reduced, which is of great significance for understanding and responding to the complex marine environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a flow chart of the method for transferring motion energy of a large ship in a wind, wave and current environment according to the present invention. DETAILED DESCRIPTION

[0030] The present invention will be described below with reference to the accompanying drawings.

[0031] The present invention relates to a method for transferring motion energy of a large ship in a wind-wave-current environment. The flow chart of the method is as follows: Figure 1 As shown, the following steps are included in sequence:

[0032] Parameter acquisition step: Acquire time domain motion signals under different ocean environments (sea breeze, waves, and currents), that is, respectively acquire the time domain motion signals of sea breeze, waves, and currents, as well as sea breeze characteristic parameters, wave characteristic parameters, and ship motion state parameters under different sea conditions. Sea breeze characteristic parameters include the circular frequency of fluctuating wind speed, the average wind speed at sea level, the correlation length of wind speed fluctuations, and the amplitude, angular frequency, and initial phase of each simple harmonic wave of fluctuating wind speed; wave characteristic parameters include the circular frequency, amplitude, wave number, wave height, and unit width of the wave. The ship motion state parameters include the volume, speed, and mass of the ship. Preferably, the wave characteristic parameters also include the wavelength, and the wave number is calculated based on the wavelength, that is, the wave number k and the wavelength λ have the following relationship: k = 2π / λ.

[0033] The power spectrum density calculation steps are as follows: the average value of the circular frequency of the fluctuating wind speed is calculated based on the circular frequency of the fluctuating wind speed, the average wind speed at sea level, and the correlation length of the wind speed fluctuations; and the power spectrum density of the fluctuating wind speed is calculated based on the average value of the circular frequency of the fluctuating wind speed, the average wind speed at sea level, and the correlation length of the wind speed fluctuations.

[0034] Specifically, for the fluctuating wind speed of the sea breeze, there is a fluctuating wind speed spectral density function. First, the average value of the fluctuating wind speed circular frequency is calculated based on the circular frequency ω of the fluctuating wind speed, the average wind speed V at sea level, and the correlation length L of the wind speed fluctuation. The power spectrum density of the fluctuating wind speed is calculated based on the average value of the circular frequency of the fluctuating wind speed, the average wind speed at sea level, and the correlation length of the wind speed fluctuation. Here, the Harris wind spectrum is used. The power spectrum density function S of the fluctuating wind speed is u (ω) is expressed as:

[0035]

[0036] Where ω is the circular frequency of the fluctuating wind speed; is the average wind speed at 10 m above sea level; κ is the surface drag coefficient (κ = 0.0025); L is the correlation length unit of wind speed fluctuation (L = 1200 m), which is used to describe the spatial correlation of wind speed fluctuations, that is, the distance over which wind speed fluctuations are correlated.

[0037] The first fluctuating wind speed model and relationship establishment steps are as follows: the first fluctuating wind speed model is established based on the amplitude, angular frequency and initial phase of each simple harmonic wave of the fluctuating wind speed; and an angular frequency interval is established according to the angular frequency and the bandwidth set based on the angular frequency. When the angular frequency is within the angular frequency interval, a relationship between the power spectral density and the amplitude of the fluctuating wind speed is constructed.

[0038] Specifically, first, a first fluctuating wind speed model is established based on the amplitude, angular frequency, and initial phase of each simple harmonic wave of the fluctuating wind speed. The first fluctuating wind speed model is expressed as follows:

[0039]

[0040] In the above formula, represents the amplitude of the nth simple harmonic wave of the pulsating wind speed, represents the angular frequency of the nth simple harmonic wave of the fluctuating wind speed at time t, ε n Indicates the initial phase of the nth simple harmonic wave of the fluctuating wind speed.

[0041] Then, the angular frequency interval is established according to the angular frequency ω and the bandwidth Δω set based on the angular frequency.

[0042] It should be noted that, in theory, the angular frequency interval (also called the wave spectrum frequency range) is [0, +∞], but in actual simulations, different wave spectrum frequency ranges are selected for different sea conditions, as shown in Table 1.

[0043] Table 1

[0044]

[0045] Preferably, the frequency division method is used to divide the frequency range of the wave spectrum under multiple different sea conditions into multiple parts, and the length of each part is set as the bandwidth, and the angular frequency interval of each wave spectrum frequency is established according to the angular frequency and the bandwidth. That is, the frequency division method is used to divide the frequency range of the wave spectrum into N parts, and the length of each part is Δω. Then the frequency range of each part is when When the angular frequency is within the angular frequency range, the relationship between the power spectrum density and the amplitude of the fluctuating wind speed is constructed, that is, the amplitude (amplitude) of the fluctuating wind speed and the power spectrum density have the following relationship:

[0046]

[0047] Where ρ is the density of seawater.

[0048] Calculation steps for fluctuating wind speed and absolute wind speed: Based on the relationship between the power spectrum density and amplitude of the fluctuating wind speed and the first fluctuating wind speed model, a second fluctuating wind speed model is obtained to further calculate the fluctuating wind speed; the absolute wind speed of the sea breeze is calculated based on the fluctuating wind speed and the average wind speed at sea level.

[0049] Specifically, firstly based on the relationship between the power spectrum density and amplitude of the fluctuating wind speed and the first fluctuating wind speed model, that is, according to

[0050] Equation 3 and Equation 2 give the second fluctuating wind speed model, as shown below:

[0051]

[0052] According to the second fluctuating wind speed model, the fluctuating wind speed v can be calculated wind , according to the pulsating wind speed v wind and the average wind speed at sea level Calculate the absolute wind speed V of the sea breeze wind , calculated according to the following formula:

[0053]

[0054] Steps for establishing the average signal power model: establish a first average signal power model based on the time domain motion signal and simulation time in any ocean environment, and use Fourier transform to convert the time domain motion signal into a frequency domain motion signal, and then obtain the Parsval energy equation about the time domain motion signal energy and the frequency domain motion signal energy according to the Parsval theorem; obtain the second average signal power model based on the first average signal power model and the Parsval energy equation, and recursively obtain the expression of the frequency domain motion signal power spectrum density based on the second average signal power model, and then recursively obtain the third average signal power model based on the second average signal power model and the expression of the frequency domain motion signal power density.

[0055] To analyze the motion of large ships in complex ocean environments from an energy perspective, we can first calculate the average power of the ocean environment and ship motion within a limited simulation time to study the energy transfer during the ship's motion. Specifically, we first establish a first average signal power model based on the time-domain motion signals in any ocean environment (including the time-domain motion signals of sea breeze, waves, and currents) and the simulation time. That is, for any time-domain motion signal f(t), the first average signal power model P can be defined as:

[0056]

[0057] Where T is the simulation time, which indicates the duration of the time domain motion signal.

[0058] The time domain motion signal f(t) is converted into the frequency domain motion signal F(jω) using Fourier transform, namely:

[0059]

[0060] According to the Parsval theorem, the Parsval energy equation for the energy of the time domain motion signal and the energy of the frequency domain motion signal is obtained. That is, the Parsval energy equation can be used to obtain the equal relationship between the energy of the signal in the time domain and the frequency domain, as shown in the following formula:

[0061]

[0062] Then, according to the first average signal power model and the Parsval energy equation (i.e., according to Equations 5 and 7), the second average signal power model is obtained, as shown in the following equation:

[0063]

[0064] Based on the second average signal power model, the expression of the power spectrum density of the frequency domain motion signal is recursively obtained. The power spectrum density of the frequency domain motion signal is defined as:

[0065]

[0066] Finally, based on the second average signal power model and the expression of frequency domain motion signal power density, the third average signal power model is obtained recursively, as shown in the following formula:

[0067]

[0068] The signal energy is represented by the average signal power P of the data. Therefore, the energy of the disturbed motion of the ship in the wind, wave and current environment can be calculated through the disturbed motion of the ship, and the relationship between the energy of the ocean environment and the disturbed energy of the ship in this process can be analyzed.

[0069] The steps for calculating the average power and energy transfer efficiency are as follows: a wave energy model is established based on the wave height and the unit width of the waves, and the average power of the waves is calculated based on the wave energy model and the third average signal power model; a disturbed sea breeze energy model is established based on the absolute wind speed and air density, and the average power of the sea breeze is calculated based on the disturbed sea breeze energy model and the third average signal power model; a ship energy model is then established based on the mass, volume and speed of the ship, and the average power of the ship is calculated based on the ship energy model and the third average signal power model; the energy transfer efficiency of the disturbed motion of the ship is calculated based on the average power of the ship, the average power of the waves and the average power of the sea breeze.

[0070] Specifically, when the surface tension of the ocean waves is ignored, the total energy of the waves within one wavelength per unit width is:

[0071] E wave =0.5ρ w gλ∫ζ 2 (t)dt (11)

[0072] Among them, ρ w represents the density of water, g represents the acceleration due to gravity, ζ represents the wave height, and λ represents the wavelength.

[0073] Therefore, the wave energy model E is established based on the wave height and unit width of the wave. wave (Also called wave unit micro-element energy E wave ), and the average power P of the waves is calculated based on the wave energy model and the third average signal power model wave , wave energy model E wave and the average power of the waves P wave They are shown as follows:

[0074]

[0075] Where b is the unit width of the wave, S ζ (ω) represents the power spectrum density of the frequency domain motion signal of the ocean wave, which can be calculated by formula (9).

[0076] Then, the disturbance sea breeze energy model E is established based on the absolute wind speed and air density. wind (also known as the unit microelement energy of the disturbed sea breeze), and the average power of the sea breeze P is calculated based on the disturbed sea breeze energy model and the third average signal power model wind , sea breeze energy model E wind and the average power of the sea breeze P wind They are shown as follows:

[0077]

[0078] In the above formula, V wind is the absolute wind speed, ρ a is the air density, T is the simulation time, and represents the duration of the time domain motion signal.

[0079] Then, the ship energy model E is established based on the ship's mass, volume and speed. ship (Also called the unit energy E of the ship's disturbed motion ship ), and the average power P of the ship is calculated based on the ship energy model and the third average signal power model ship , energy model E ship and the average power of the ship P ship They are shown as follows:

[0080]

[0081] in, is the volume of the ship, L, B, and H are the length, width, and depth of the ship respectively, m is the mass of the ship, v is the speed of the ship, and i is the six degrees of freedom, which are surge, sway, heave, pitch, roll, and bow roll.

[0082] Finally, the energy transfer efficiency of the ship's disturbed motion under different sea conditions is calculated based on the average power of the ship, the average power of the waves, and the average power of the sea breeze. The calculation is based on the following formula:

[0083]

[0084] After calculating the energy transfer efficiency of a ship's disturbed motion under different sea conditions, a simulation test was conducted on a Nimitz-type ship to examine its energy transfer efficiency as it changes with sea state level, in a complex wind, wave, and current environment ranging from level 1 to level 8. The test results show that at zero speed, the energy transfer efficiency of the ship's disturbed motion increases with increasing sea state level, with the highest energy transfer efficiency in heave, roll, and pitch in sea state levels 8, respectively, achieving the highest energy transfer efficiency.

[0085] The present invention also relates to a large ship motion energy transfer system in a wind-wave and current environment. The system corresponds to the above-mentioned large ship motion energy transfer method in a wind-wave and current environment and can be understood as a system for implementing the above-mentioned method. The system includes a parameter acquisition module, a power spectrum density calculation module, a first fluctuating wind speed model and relationship establishment module, a fluctuating wind speed and absolute wind speed calculation module, an average signal power model establishment module, and an average power and energy transfer efficiency calculation module, which are connected in sequence. Specifically,

[0086] The parameter acquisition module acquires time domain motion signals under different ocean environments, as well as sea breeze characteristic parameters, wave characteristic parameters and ship motion state parameters under different sea conditions. The sea breeze characteristic parameters include the circular frequency of the fluctuating wind speed, the average wind speed at sea level, the correlation length of the wind speed fluctuation, and the amplitude, angular frequency and initial phase of each simple harmonic wave of the fluctuating wind speed; the wave characteristic parameters include the circular frequency, amplitude, wave number, wave height and unit width of the wave; the ship motion state parameters include the volume, speed and mass of the ship;

[0087] The power spectrum density calculation module calculates the average value of the circular frequency of the fluctuating wind speed according to the circular frequency of the fluctuating wind speed, the average wind speed at sea level, and the correlation length of the wind speed fluctuation, and calculates the power spectrum density of the fluctuating wind speed according to the average value of the circular frequency of the fluctuating wind speed, the average wind speed at sea level, and the correlation length of the wind speed fluctuation;

[0088] The first fluctuating wind speed model and relationship establishment module establishes the first fluctuating wind speed model based on the amplitude, angular frequency, and initial phase of each simple harmonic wave of the fluctuating wind speed; establishes an angular frequency interval based on the angular frequency and a bandwidth set based on the angular frequency, and constructs a relationship between the power spectrum density and the amplitude of the fluctuating wind speed when the angular frequency is within the angular frequency interval;

[0089] The fluctuating wind speed and absolute wind speed calculation module obtains a second fluctuating wind speed model based on the relationship between the power spectrum density and amplitude of the fluctuating wind speed and the first fluctuating wind speed model, and then calculates the fluctuating wind speed; and calculates the absolute wind speed of the sea breeze based on the fluctuating wind speed and the average wind speed at sea level;

[0090] The average signal power model establishment module establishes a first average signal power model based on the time domain motion signal and simulation time in any ocean environment, and uses Fourier transform to convert the time domain motion signal into a frequency domain motion signal, and then obtains the Parsval energy equation for the time domain motion signal energy and the frequency domain motion signal energy according to the Parsval theorem; obtains a second average signal power model based on the first average signal power model and the Parsval energy equation, and recursively obtains an expression for the power spectrum density of the frequency domain motion signal based on the second average signal power model, and then recursively obtains a third average signal power model based on the second average signal power model and the expression for the power density of the frequency domain motion signal;

[0091] The average power and energy transfer efficiency calculation module establishes a wave energy model based on the wave height and the unit width of the waves, and calculates the average power of the waves according to the wave energy model and the third average signal power model; establishes a disturbed sea breeze energy model based on the absolute wind speed and air density, and calculates the average power of the sea breeze according to the disturbed sea breeze energy model and the third average signal power model; then establishes a ship energy model based on the mass, volume and speed of the ship, and calculates the average power of the ship according to the ship energy model and the third average signal power model; and calculates the energy transfer efficiency of the disturbed motion of the ship under different sea conditions according to the average power of the ship, the average power of the waves and the average power of the sea breeze.

[0092] Preferably, in the first pulsating wind speed model and relationship establishment module, establishing the angular frequency interval according to the angular frequency and the bandwidth set based on the angular frequency includes: using the frequency equal division method to divide the wave spectrum frequency range under multiple different sea conditions into multiple parts, and setting the length of each part as the bandwidth, and establishing the angular frequency interval of each wave spectrum frequency according to the angular frequency and the bandwidth.

[0093] Preferably, the time domain motion signals under different ocean environments include the time domain motion signals of sea breeze, the time domain motion signals of ocean waves and the time domain motion signals of ocean currents; the ocean wave characteristic parameters also include wavelength, and the wave number is calculated based on the wavelength.

[0094] Preferably, in the parameter acquisition module, when obtaining the correlation length of wind speed fluctuation, the correlation length of wind speed fluctuation is obtained by statistically analyzing the wind speed data at multiple different time points to improve the adaptability of the model to wind speed changes on different time scales.

[0095] The present invention provides an objective and scientific method and system for transferring energy of large ship motion in a wind, wave and current environment. Based on the characteristic parameters of sea breeze, wave characteristics and motion state parameters of the ship under different sea conditions, a specific calculation method is used to construct a pulsating wind speed model to calculate the absolute wind speed, and then the energy transfer efficiency of the disturbed motion of the ship under different sea conditions is calculated. By fully considering the mutual influence and action between sea breeze, waves and currents under different sea conditions, the motion amplitude of the ship in complex sea conditions can be effectively reduced, which is of great significance for understanding and responding to complex marine environments.

[0096] It should be noted that the specific embodiments described above can enable those skilled in the art to more fully understand the present invention, 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 replaced with equivalents. In short, all technical solutions and improvements that do not depart from the spirit and scope of the present invention should be included in the scope of protection of the patent for the present invention.

Claims

1. A method for transferring motion energy of a large ship in a wind, wave and current environment, characterized in that: The following steps are involved: Parameter acquisition step: acquiring time domain motion signals under different ocean environments, as well as sea breeze characteristic parameters, wave characteristic parameters and ship motion state parameters under different sea conditions, wherein the sea breeze characteristic parameters include the circular frequency of the fluctuating wind speed, the average wind speed at sea level, the correlation length of the wind speed fluctuation, and the amplitude, angular frequency and initial phase of each simple harmonic wave of the fluctuating wind speed; the wave characteristic parameters include the circular frequency, amplitude, wave number, wave height and unit width of the wave; and the ship motion state parameters include the volume, speed and mass of the ship; Power spectrum density calculation steps: Calculate the average value of the circular frequency of the fluctuating wind speed based on the circular frequency of the fluctuating wind speed, the average wind speed at sea level, and the correlation length of the wind speed fluctuations, and calculate the power spectrum density of the fluctuating wind speed based on the average value of the circular frequency of the fluctuating wind speed, the average wind speed at sea level, and the correlation length of the wind speed fluctuations; The first fluctuating wind speed model and relationship establishment step includes: establishing the first fluctuating wind speed model based on the amplitude, angular frequency, and initial phase of each simple harmonic wave of the fluctuating wind speed; establishing an angular frequency interval based on the angular frequency and a frequency bandwidth set based on the angular frequency; and constructing a relationship between the power spectral density and the amplitude of the fluctuating wind speed when the angular frequency is within the angular frequency interval; Calculation steps for fluctuating wind speed and absolute wind speed: Based on the relationship between the power spectrum density and amplitude of the fluctuating wind speed and the first fluctuating wind speed model, a second fluctuating wind speed model is obtained to further calculate the fluctuating wind speed; the absolute wind speed of the sea breeze is calculated based on the fluctuating wind speed and the average wind speed at sea level; The steps of establishing the average signal power model are as follows: a first average signal power model is established based on the time domain motion signal and simulation time in any ocean environment, and the time domain motion signal is converted into a frequency domain motion signal by Fourier transform, and then the Parsval energy equation for the energy of the time domain motion signal and the energy of the frequency domain motion signal is obtained according to the Parsval theorem; a second average signal power model is obtained according to the first average signal power model and the Parsval energy equation, and an expression for the power spectrum density of the frequency domain motion signal is recursively obtained based on the second average signal power model, and a third average signal power model is then recursively obtained based on the second average signal power model and the expression for the power density of the frequency domain motion signal; The steps for calculating the average power and energy transfer efficiency are as follows: a wave energy model is established based on the wave height and the unit width of the waves, and the average power of the waves is calculated based on the wave energy model and the third average signal power model; a disturbed sea breeze energy model is established based on the absolute wind speed and air density, and the average power of the sea breeze is calculated based on the disturbed sea breeze energy model and the third average signal power model; a ship energy model is then established based on the mass, volume and speed of the ship, and the average power of the ship is calculated based on the ship energy model and the third average signal power model; the energy transfer efficiency of the disturbed motion of the ship under different sea conditions is calculated based on the average power of the ship, the average power of the waves and the average power of the sea breeze.

2. The method for transferring motion energy of a large ship in a wind, wave and current environment according to claim 1, characterized in that: In the step of establishing the first pulsating wind speed model and the relationship, establishing the angular frequency interval according to the angular frequency and the bandwidth set based on the angular frequency includes: using the frequency equal division method to divide the wave spectrum frequency range under multiple different sea conditions into multiple parts, and setting the length of each part as the bandwidth, and establishing the angular frequency interval of each wave spectrum frequency according to the angular frequency and the bandwidth.

3. The method for transferring motion energy of a large ship in a wind, wave and current environment according to claim 1, characterized in that: In the parameter acquisition step, the time domain motion signals under different ocean environments include the time domain motion signals of sea breeze, the time domain motion signals of waves and the time domain motion signals of ocean currents; the wave characteristic parameters also include wavelength, and the wave number is calculated based on the wavelength.

4. The method for transferring motion energy of a large ship in a wind, wave and current environment according to claim 1, characterized in that: In the parameter acquisition step, when obtaining the correlation length of wind speed fluctuation, the correlation length of wind speed fluctuation is obtained by statistically analyzing the wind speed data at multiple different time points to improve the adaptability of the model to wind speed changes on different time scales.

5. A large ship motion energy transfer system in a wind, wave and current environment, characterized in that: It includes a parameter acquisition module, a power spectrum density calculation module, a first fluctuating wind speed model and relationship establishment module, a fluctuating wind speed and absolute wind speed calculation module, an average signal power model establishment module, and an average power and energy transfer efficiency calculation module, which are connected in sequence. The parameter acquisition module acquires time domain motion signals under different ocean environments, as well as sea breeze characteristic parameters, wave characteristic parameters and ship motion state parameters under different sea conditions. The sea breeze characteristic parameters include the circular frequency of the fluctuating wind speed, the average wind speed at sea level, the correlation length of the wind speed fluctuation, and the amplitude, angular frequency and initial phase of each simple harmonic wave of the fluctuating wind speed; the wave characteristic parameters include the circular frequency, amplitude, wave number, wave height and unit width of the wave; the ship motion state parameters include the volume, speed and mass of the ship; The power spectrum density calculation module calculates the average value of the circular frequency of the fluctuating wind speed according to the circular frequency of the fluctuating wind speed, the average wind speed at sea level, and the correlation length of the wind speed fluctuation, and calculates the power spectrum density of the fluctuating wind speed according to the average value of the circular frequency of the fluctuating wind speed, the average wind speed at sea level, and the correlation length of the wind speed fluctuation; The first fluctuating wind speed model and relationship establishment module establishes the first fluctuating wind speed model based on the amplitude, angular frequency, and initial phase of each simple harmonic wave of the fluctuating wind speed; establishes an angular frequency interval based on the angular frequency and a bandwidth set based on the angular frequency, and constructs a relationship between the power spectrum density and the amplitude of the fluctuating wind speed when the angular frequency is within the angular frequency interval; The fluctuating wind speed and absolute wind speed calculation module obtains a second fluctuating wind speed model based on the relationship between the power spectrum density and amplitude of the fluctuating wind speed and the first fluctuating wind speed model, and then calculates the fluctuating wind speed; and calculates the absolute wind speed of the sea breeze based on the fluctuating wind speed and the average wind speed at sea level; The average signal power model establishment module establishes a first average signal power model based on the time domain motion signal and simulation time in any ocean environment, and uses Fourier transform to convert the time domain motion signal into a frequency domain motion signal, and then obtains the Parsval energy equation for the energy of the time domain and frequency domain motion signals according to the Parsval theorem; obtains a second average signal power model based on the first average signal power model and the Parsval energy equation, and recursively obtains an expression for the power spectrum density of the frequency domain motion signal based on the second average signal power model, and then recursively obtains a third average signal power model based on the second average signal power model and the expression for the power density of the frequency domain motion signal; The average power and energy transfer efficiency calculation module establishes a wave energy model based on the wave height and the unit width of the waves, and calculates the average power of the waves according to the wave energy model and the third average signal power model; establishes a disturbed sea breeze energy model based on the absolute wind speed and air density, and calculates the average power of the sea breeze according to the disturbed sea breeze energy model and the third average signal power model; then establishes a ship energy model based on the mass, volume and speed of the ship, and calculates the average power of the ship according to the ship energy model and the third average signal power model; and calculates the energy transfer efficiency of the disturbed motion of the ship under different sea conditions according to the average power of the ship, the average power of the waves and the average power of the sea breeze.

6. The large ship motion energy transfer system in wind, wave and current environment according to claim 5, characterized in that: In the first pulsating wind speed model and relationship establishment module, establishing an angular frequency interval according to the angular frequency and the bandwidth set based on the angular frequency includes: using a frequency equal division method to divide the wave spectrum frequency range under multiple different sea conditions into multiple parts, and setting the length of each part as the bandwidth, and establishing an angular frequency interval for each wave spectrum frequency according to the angular frequency and the bandwidth.

7. The large ship motion energy transfer system in wind, wave and current environment according to claim 5, characterized in that: The time domain motion signals under different ocean environments include the time domain motion signals of sea breeze, the time domain motion signals of ocean waves and the time domain motion signals of ocean currents; the ocean wave characteristic parameters also include wavelength, and the wave number is calculated based on the wavelength.

8. The large ship motion energy transfer system in wind, wave and current environment according to claim 5, characterized in that: In the parameter acquisition module, when obtaining the correlation length of wind speed fluctuation, the correlation length of wind speed fluctuation is obtained by statistically analyzing the wind speed data at multiple different time points, so as to improve the adaptability of the model to wind speed changes on different time scales.

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