Ocean current dynamic response analysis method and system based on wind wave current coupling relation

Abstract

The invention provides an ocean current dynamic response analysis method and system based on a wind wave current coupling relationship, and the method comprises the steps: building a first fluctuating wind speed model based on sea wind characteristic parameters, sea wave characteristic parameters and motion state parameters of a ship under different sea conditions, and calculating the power spectrum density of the fluctuating wind speed through employing a specific calculation method; constructing a relational expression between the power spectrum density and the amplitude of the fluctuating wind speed in the angular frequency interval range; a second fluctuating wind speed model is obtained through the relational expression and the first fluctuating wind speed model, and then the absolute wind speed of the sea wind is calculated; the method comprises the following steps: calculating the sexual wave height of sea waves according to the absolute wind speed, respectively calculating the flow velocity of wind-induced flow and wave-induced flow by adopting a specific calculation method, further constructing an ocean current flow velocity model, and calculating the disturbing force of ocean current on a ship by adopting the specific calculation method based on the ocean current flow velocity model. By fully considering the mutual influence among the sea wind, the sea wave and the ocean current, the dynamic response of the ship in the wind wave current can be predicted more accurately.

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 analyzing ocean current dynamic response based on wind-wave-current coupling relationship. Background Art

[0002] As a maritime power, my country has vast seas and long coastlines. It is surrounded by the four seas of Bohai, Yellow Sea, East China Sea and South China Sea. It has more than 6,500 islands, about 40 billion tons of marine oil and gas and other rich marine resources. With continuous development, my country's marine economy has become an important part of my country's overall economy. In 2023, my country's marine gross output value was 9909.7 billion yuan, accounting for 7.9% of GDP, among which my country's port shipping, shipbuilding and other marine industries played a key role. my country's marine transportation volume is huge, especially container transportation volume, which is the world's first. In 2023, my country occupied 7 seats in the top ten ports in the world in terms of throughput; my country's shipbuilding industry continued to lead the world in terms of total volume. In 2023, my country's shipbuilding industry completed volume, backlog of orders, and international market share of new orders were all the first in the world, and successfully delivered many large ships such as 24,000TEU ultra-large container ships, ultra-large ethylene carriers, and large cruise ships.

[0003] Large ships will be affected by the marine environment during their ocean voyages, among which sea breeze, waves and currents are the most important environmental factors affecting the movement of large ships. Sea breeze refers to the flow of air at sea along the pressure gradient. Sea waves refer to the fluctuation of sea water in the ocean, where "fluctuation" refers to the periodic or quasi-periodic movement of water particles away from the equilibrium position under the action of external forces. Ocean currents refer to the large-scale and relatively stable flow of sea water, where "large-scale and relatively stable flow" means flow with roughly similar direction, speed and flow path over a large-scale space and over a long period of time. Sea breeze refers to the flow of air at sea along the pressure gradient. As an important source of energy for the global ocean, sea breeze affects the formation of waves and currents.

[0004] Due to the vast sea territory and large transportation volume of my country, in some cases there will be mission requirements for navigation operations in complex marine environments. In order to ensure the safety and stability of ship navigation and the smooth progress of marine operations, it is necessary to clarify the mechanism of the impact of the marine environment on the movement of large ships. The impact of the marine environment on ships is mainly through the effects of sea breeze, waves, and currents. Since the characteristics of sea breeze, waves, and currents are different in different sea conditions, the disturbance effect on ships is also different. By changing the characteristic parameters of sea breeze, waves, and currents, the influence characteristics on the disturbed motion of ships are studied, so as to provide a reference for safety analysis and give suggestions for navigation tasks.

[0005] In summary, the sea breeze, waves, and currents in the marine environment interact with each other and have a complex coupling relationship. Therefore, it is difficult to simulate the wind, wave, and current based on the generation mechanism. In addition, in the current research on the disturbance effect on ships, the disturbance force calculation method fails to fully consider the impact of the interaction between wind, waves, and currents on ships, and cannot more realistically describe the wind, wave, and current environment under different sea conditions. Summary of the invention

[0006] The present invention aims at the problems that the interaction between sea breeze, waves and currents is not considered in the current research on the disturbance effect of ships, and the wind, wave and current environment under different sea conditions cannot be truly simulated. The present invention provides a method for analyzing the dynamic response of sea current based on the wind, wave and current coupling relationship. Based on the sea breeze characteristic parameters, wave characteristic parameters and the motion state parameters of the ship under different sea conditions, a fluctuating wind speed model is constructed by a specific calculation method to calculate the fluctuating wind speed and the significant wave height of the waves, and then a current velocity model is constructed. Based on the current velocity model and a specific calculation method, the disturbance force (dynamic response) of the current on the ship is calculated. By fully considering the interaction between sea breeze, waves and currents, the dynamic response of the ship in the wind, wave and current can be predicted more accurately, and the calculation accuracy is effectively improved. The present invention also relates to a system for analyzing the dynamic response of sea current based on the wind, wave and current coupling relationship.

[0007] The technical solution of the present invention is as follows:

[0008] A method for analyzing ocean current dynamic response based on wind-wave-current coupling relationship, characterized in that it comprises the following steps:

[0009] Parameter acquisition and coordinate system establishment steps: obtain sea breeze characteristic parameters, wave characteristic parameters and ship motion state parameters under different sea conditions, and establish a stable coordinate system of the hull with the ship's center of mass as the origin, the ship's motion direction as the longitudinal axis, the starboard side of the ship and the direction parallel to the sea level as the transverse axis, and the center of the earth as the vertical axis; 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 and wave number of the wave; the ship's motion state parameters include the ship's speed, waterline length, draft and length;

[0010] Power spectrum density calculation steps: calculate 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 calculate 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;

[0011] The first fluctuating wind speed model and relationship establishment step: 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; and establishing an angular frequency interval according to the angular frequency and the bandwidth set based on the angular frequency, and when the angular frequency is within the angular frequency interval, constructing a relationship between the power spectrum density and the amplitude of the fluctuating wind speed;

[0012] Absolute wind speed calculation steps: 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, and then the fluctuating wind speed is calculated; the absolute wind speed of the sea breeze is calculated according to the fluctuating wind speed and the average wind speed at sea level;

[0013] The steps of constructing the ocean current velocity model are as follows: the significant wave height of the ocean waves is calculated according to the absolute wind speed of the sea breeze, and the water friction velocity is calculated according to the average wind speed, air density and seawater density at the sea level, and then the velocity of the wind-induced current is calculated according to the water friction velocity; the velocity of the wave-induced current is calculated according to the significant wave height, circular frequency, amplitude and wave number of the waves, and the ocean current velocity model is constructed based on the velocity of the wind-induced current and the velocity of the wave-induced current;

[0014] The steps for calculating the interference force of ocean current on ships are as follows: the ocean current velocity is calculated according to the ocean current velocity model, and the angle between the ocean current flow direction and the ship's sailing direction is taken as the relative flow angle of the ocean current; in the stable coordinate system of the hull, the velocity components of the ocean current in the longitudinal and transverse axis directions are calculated according to the ocean current velocity and the relative flow angle; and the first relative velocity between the ship and the ocean current in the longitudinal axis direction is calculated according to the velocity component of the ocean current in the longitudinal axis direction and the speed of the ship in the longitudinal axis direction under the condition of no wind and current; and the second relative velocity between the ship and the ocean current in the transverse axis direction is calculated according to the velocity component of the ocean current in the transverse axis direction and the speed of the ship in the transverse axis direction under the condition of no wind and current; and then the relative velocity of the ocean current is calculated according to the first relative velocity and the second relative velocity; and the roll interference force, pitch interference force and heave interference force of the ocean current on the ship are calculated according to the relative velocity of the ocean current, the waterline length, the draft and the length of the ship.

[0015] 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.

[0016] Preferably, in the parameter acquisition and coordinate system establishment steps, the wave characteristic parameters also include wavelength, and the wave number is calculated based on the wavelength.

[0017] 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 statistically analyzing wind speed data at multiple different time points to improve the adaptability of the model to wind speed changes on different time scales.

[0018] A current dynamic response analysis system based on wind-wave-current coupling relationship, characterized in that it comprises a parameter acquisition and coordinate system establishment module, a power spectrum density calculation module, a first pulsating wind speed model and relationship establishment module, an absolute wind speed calculation module, a current velocity model construction module and a current interference force calculation module on ships, which are connected in sequence.

[0019] The parameter acquisition and coordinate system establishment module acquires sea breeze characteristic parameters, sea wave characteristic parameters and ship motion state parameters under different sea conditions, and establishes a stable coordinate system of the hull with the ship's center of mass as the origin, the ship's motion direction as the longitudinal axis, the starboard side of the ship and parallel to the sea level as the transverse axis, and the center of the earth as the vertical axis; 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 sea wave characteristic parameters include the circular frequency, amplitude and wave number of the wave; the ship's motion state parameters include the ship's speed, waterline length, draft and length;

[0020] 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;

[0021] 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; and establishes an angular frequency interval according to the angular frequency and the bandwidth set based on the angular frequency, and when the angular frequency is within the angular frequency interval, constructs a relationship between the power spectrum density and the amplitude of the fluctuating wind speed;

[0022] The absolute wind speed calculation module obtains a second pulsating wind speed model based on the relationship between the power spectrum density and amplitude of the pulsating wind speed and the first pulsating wind speed model, and then calculates the pulsating wind speed; and calculates the absolute wind speed of the sea breeze according to the pulsating wind speed and the average wind speed at sea level;

[0023] The ocean current velocity model construction module calculates the significant wave height of the waves according to the absolute wind speed of the sea breeze, and calculates the water flow friction speed according to the average wind speed, air density and seawater density at the sea level, and then calculates the flow velocity of the wind-induced current according to the water flow friction speed; and then calculates the flow velocity of the wave-induced current according to the significant wave height, the circular frequency, amplitude and wave number of the waves, and constructs the ocean current velocity model based on the flow velocity of the wind-induced current and the flow velocity of the wave-induced current.

[0024] The module for calculating the interference force of the ocean current on the ship calculates the ocean current velocity according to the ocean current velocity model, and takes the angle between the ocean current flow direction and the navigation direction of the ship as the relative flow angle of the ocean current, and calculates the velocity components of the ocean current in the longitudinal and transverse axis directions according to the ocean current velocity and the relative flow angle in the stable coordinate system of the hull; and calculates the first relative speed of the ship and the ocean current in the longitudinal axis direction according to the velocity component of the ocean current in the longitudinal axis direction and the speed of the ship in the longitudinal axis direction under the condition of no wind and current, and calculates the second relative speed of the ship and the ocean current in the transverse axis direction according to the velocity component of the ocean current in the transverse axis direction and the speed of the ship in the transverse axis direction under the condition of no wind and current; and then calculates the relative speed of the ocean current according to the first relative speed and the second relative speed; and calculates the roll interference force, pitch interference force and heave interference force of the ocean current on the ship according to the relative speed of the ocean current, the waterline length, the draft and the length of the ship.

[0025] Preferably, in the first pulsating wind speed model and relationship establishing module, establishing an 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.

[0026] Preferably, the ocean wave characteristic parameters also include wavelength, and the wave number is calculated based on the wavelength.

[0027] Preferably, in the parameter acquisition module, when acquiring 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.

[0028] The beneficial effects of the present invention are:

[0029] The present invention provides a method for analyzing the dynamic response of ocean currents based on the coupling relationship between wind, wave and current. The method is based on the characteristic parameters of sea breeze and sea wave under different sea conditions, and uses a specific calculation method to calculate the power spectrum density of the pulsating wind speed, which can effectively reveal the energy distribution of wind speed fluctuations. Then, a first pulsating wind speed model is established based on the amplitude, angular frequency and initial phase of each simple harmonic wave of the pulsating 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. 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 pulsating wind speed is constructed, which can better identify the degree of contribution of different frequency components to the total wind speed, help identify the main disturbance source, thereby optimizing the prediction model, and can intuitively display the energy distribution of different frequency components. Finally, the absolute wind speed of the ocean breeze is calculated. The significant wave height of the sea waves is obtained, and the influence of the wind speed on the sea waves is fully considered, which is helpful to comprehensively evaluate the effect of wind on the wave shape on the sea surface; and the water friction speed is calculated according to the average wind speed, air density and seawater density at sea level, and then the flow velocity of the wind-induced current is calculated according to the water friction speed, which can more comprehensively describe the influence of wind on the movement of sea water; the flow velocity of the wave-induced current is calculated according to the significant wave height, the circular frequency of the wave, the amplitude and the wave number, which can more comprehensively describe the influence of waves on the ocean current; the ocean current velocity model is constructed based on the flow velocity of the wind-induced current and the flow velocity of the wave-induced current, and finally the ocean current on the ship The roll interference force, pitch interference force and heave interference force (dynamic response) are calculated based on the ocean current velocity model and a specific calculation method. By fully considering the interaction between sea breeze, waves and ocean currents, the dynamic response of the ship in wind, waves and currents can be more accurately predicted, which effectively improves the calculation accuracy, which is of great significance for understanding and responding to complex marine environments.

[0030] The present invention also relates to a system for analyzing the dynamic response of ocean currents based on the coupling relationship between wind, wave and current. The system corresponds to the above-mentioned method for analyzing the dynamic response of ocean currents based on the coupling relationship between wind, wave and current, and can be understood as a system for realizing the above-mentioned method for analyzing the dynamic response of ocean currents based on the coupling relationship between wind, wave and current, including a parameter acquisition module, a power spectrum density calculation module, a first pulsating wind speed model and a relationship establishment module, an absolute wind speed calculation module and an ocean current velocity model construction module connected in sequence. The modules cooperate with each other, based on the characteristic parameters of sea breeze, characteristic parameters of waves and motion state parameters of ships under different sea conditions, and using a specific calculation method to construct a pulsating wind speed model to calculate the pulsating wind speed and the significant wave height of waves, and then construct an ocean current velocity model. Based on the ocean current velocity model and using a specific calculation method, the interference force (dynamic response) of the ocean current on the ship is calculated. By fully considering the interaction between sea breeze, waves and currents, the dynamic response of the ship in wind, wave and current can be more accurately predicted, effectively improving the calculation accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a flow chart of the ocean current dynamic response analysis method based on the wind-wave-current coupling relationship of the present invention.

[0032] Figure 2 It is a schematic diagram of the hull stability coordinate system of the present invention. DETAILED DESCRIPTION

[0033] The present invention will be described below in conjunction with the accompanying drawings.

[0034] The present invention relates to a method for analyzing ocean current dynamic response based on wind-wave-current coupling relationship. The flow chart of the method is as follows: Figure 1 As shown, the following steps are included in sequence:

[0035] Parameter acquisition steps: obtain the sea breeze characteristic parameters, wave characteristic parameters and ship motion state parameters under different sea conditions, and establish a stable coordinate system of the hull with the ship's center of mass as the origin, the ship's motion direction as the longitudinal axis, the starboard side of the ship and parallel to the sea level as the transverse axis, and the center of the earth as the vertical axis; the sea breeze characteristic parameters include the circular frequency of the pulsating 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 pulsating wind speed; the wave characteristic parameters include the circular frequency, amplitude and wave number of the waves; the ship's motion state parameters include the ship's speed, waterline length, draft and length.

[0036] Specifically, the hull stable coordinate system Ox s y s z s like Figure 2 As shown in Figure 1, it is a coordinate system that moves with the ship and is used to describe the motion of the ship hull in a stable state. The origin of the coordinate system O is the center of mass of the ship, and the direction of motion of the ship is the longitudinal axis, that is, Ox s The axis points to the direction of the ship's motion, and the direction to the starboard side of the ship and parallel to the sea level is the transverse axis, that is, Oy s Pointing to the starboard side of the ship and parallel to the sea level, with the center of the earth as the vertical axis, i.e. Oz s The axis points to the center of the earth, Ox s y s The plane is parallel to the sea level, and the distribution of the three coordinate axes conforms to the right-hand rule. Preferably, the wave characteristic parameter also includes the wavelength, and the wave number is calculated according to the wavelength, that is, the wave number k and the wavelength λ have the following relationship: k=2π / λ.

[0037] The steps for calculating the power spectral density are as follows: the average value of the circular frequency of the pulsating wind speed is calculated according to the circular frequency of the pulsating wind speed, the average wind speed at sea level and the correlation length of the wind speed fluctuations, and the power spectral density of the pulsating wind speed is calculated according to the average value of the circular frequency of the pulsating wind speed, the average wind speed at sea level and the correlation length of the wind speed fluctuations.

[0038] 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:

[0039]

[0040] Where, ω is the circular frequency of the pulsating 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, over what distance the wind speed fluctuations are correlated.

[0041] The first pulsating wind speed model and relationship establishment steps are as follows: the first pulsating wind speed model is established based on the amplitude, angular frequency and initial phase of each simple harmonic wave of the pulsating 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 spectrum density and the amplitude of the pulsating wind speed is constructed.

[0042] Specifically, firstly, 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:

[0043]

[0044] 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 pulsating wind speed.

[0045] Then, the angular frequency interval is established according to the angular frequency ω and the bandwidth Δω set based on the angular frequency

[0046] It should be noted that, in theory, the angular frequency interval (also called the wave spectrum frequency range) is [0, +∞], while in actual simulation, different wave spectrum frequency ranges are selected for different sea conditions, as shown in Table 1.

[0047] Table 1

[0048]

[0049] 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, each part is Δω long, and the frequency range of each part is when When (that is, when the angular frequency is within the angular frequency interval), 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:

[0050]

[0051] Here, ρ is the density of seawater.

[0052] Absolute wind speed calculation steps: Based on the relationship between the power spectrum density and amplitude of the fluctuating wind speed and the first fluctuating wind speed model, the second fluctuating wind speed model is obtained, and then the fluctuating wind speed is calculated; the absolute wind speed of the sea breeze is calculated according to the fluctuating wind speed and the average wind speed at sea level.

[0053] 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

[0054] Equation 3 and Equation 2 give the second fluctuating wind speed model, as shown below:

[0055]

[0056] According to the second pulsating wind speed model, the pulsating 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:

[0057]

[0058] The steps for constructing the ocean current velocity model are as follows: the significant wave height of the waves is calculated according to the absolute wind speed of the sea breeze, and the water friction speed is calculated according to the average wind speed, air density and seawater density at sea level, and then the velocity of the wind-induced current is calculated according to the water friction speed; the velocity of the wave-induced current is calculated according to the significant wave height, circular frequency, amplitude and wave number of the waves, and the ocean current velocity model is constructed based on the velocity of the wind-induced current and the velocity of the wave-induced current.

[0059] Specifically, first, according to the absolute wind speed V of the sea breeze wind Calculate the significant wave height H of the ocean wave 1 / 3, calculated according to the following formula:

[0060]

[0061] Then the water flow friction speed u is calculated based on the average wind speed, air density and seawater density at sea level. *w , calculated according to the following formula:

[0062]

[0063] Among them, C z is the wind stress coefficient, C v is the wave resistance coefficient, is the average wind speed at height z above sea level, ρ a is the air density, ρ w is the density of sea water.

[0064] Among them, the wind stress coefficient C z The calculation formula is:

[0065]

[0066] In the above formula, a is the Charnock coefficient, which is 0.185; F r The calculation formula for Froude number is:

[0067]

[0068] The recommended height z calculation formula is:

[0069] z=7.35R 2 / 3 ×10 -7 (10)

[0070] In the above formula, R is the wind Reynolds number, and the calculation formula is:

[0071]

[0072] In the above formula, v a is the dynamic viscosity of air; L wind The wind range usually refers to the distance of open waters that the wind blows through. The value here refers to the minimum wind zone length under full development conditions of different sea conditions.

[0073] According to the water flow friction speed u *w Calculate the velocity of wind-induced flow according to the following formula:

[0074] V n =22u *w (12)

[0075] The velocity of the wave-induced flow is then calculated based on the significant wave height, circular frequency, amplitude and wave number. The velocity of the wave-induced flow V v The calculation formula is:

[0076]

[0077] Among them, ω is the circular frequency of the wave, ζ a is the amplitude (wave amplitude), H 1 / 3 is the significant wave height, and k is the wave number.

[0078] Finally, the ocean current velocity model is constructed based on the velocity of wind-induced current and wave-induced current. The ocean current velocity (i.e., the velocity of ocean surface current) V c It can be expressed as:

[0079] V c =V n +V v (14)

[0080] The steps for calculating the interference force of ocean current on ships are as follows: the ocean current velocity is calculated according to the ocean current velocity model, and the angle between the ocean current flow direction and the ship's sailing direction is taken as the relative flow angle of the ocean current; in the stable coordinate system of the hull, the velocity components of the ocean current in the longitudinal and transverse axis directions are calculated according to the ocean current velocity and the relative flow angle; and the first relative velocity between the ship and the ocean current in the longitudinal axis direction is calculated according to the velocity component of the ocean current in the longitudinal axis direction and the speed of the ship in the longitudinal axis direction under the condition of no wind and current; and the second relative velocity between the ship and the ocean current in the transverse axis direction is calculated according to the velocity component of the ocean current in the transverse axis direction and the speed of the ship in the transverse axis direction under the condition of no wind and current; and then the relative velocity of the ocean current is calculated according to the first relative velocity and the second relative velocity; and the roll interference force, pitch interference force and heave interference force of the ocean current on the ship are calculated according to the relative velocity of the ocean current, the waterline length, the draft and the length of the ship.

[0081] Specifically, firstly, the ocean current velocity V is calculated according to the ocean current velocity model. C , and the angle between the current flow direction and the ship's sailing direction is taken as the relative flow angle χ C , in the hull stable coordinate system, according to the ocean current velocity V C and the relative flow angle χ C The velocity components of the ocean current in the longitudinal axis (i.e., x-axis) and the transverse axis (i.e., y-axis) directions are calculated respectively according to the following formulas:

[0082]

[0083] Among them, u C represents the velocity component of the ocean current in the x-axis (longitudinal axis) direction; vC It represents the velocity component of the ocean current in the y-axis (horizontal axis) direction.

[0084] Then according to the velocity component u of the ocean current in the longitudinal axis (i.e., x-axis) C , and the ship's speed u in the longitudinal direction under no wind and current conditions to calculate the first relative speed u between the ship and the current in the longitudinal direction r ; or according to the velocity component u of the ocean current in the longitudinal axis direction C , the velocity component v of the current in the transverse axis direction C , and the ship's speed u in the longitudinal direction under no wind and current conditions. Calculate the first relative speed u between the ship and the current in the longitudinal direction (x axis) r , calculated according to the following formula:

[0085] u r =u-(u C cosX C +v C sinx C )=uu c (16)

[0086] And according to the velocity component v of the ocean current in the transverse axis (i.e., y axis) direction C , and the ship's speed v in the longitudinal direction under no wind and current conditions to calculate the second relative speed v between the ship and the current in the longitudinal direction r ; or according to the velocity component u of the ocean current in the longitudinal axis direction C , the velocity component v of the current in the transverse axis direction C , and under the condition of no wind and current, the ship's speed v in the transverse axis direction is used to calculate the second relative speed v between the ship and the current in the longitudinal axis (y axis) direction r , calculated according to the following formula:

[0087] v r =v-(-u C sinx C +v C cos C )=vv c (17)

[0088] Then according to the first relative speed u r and the second relative velocity v r Calculate the relative velocity V of the ocean current r,C , calculated according to the following formula:

[0089]

[0090] Finally, according to the relative speed of the ocean current, the waterline length, draft and length of the ship, the rolling interference force, pitching interference force and heaving interference force of the ocean current on the ship are calculated respectively according to the following formulas:

[0091]

[0092] In the above formula, C X ,C Y ,C N are the rolling disturbance force coefficient, pitching disturbance force coefficient and heaving disturbance force coefficient respectively; ρ is the density of seawater; A is the product of the ship's waterline length and draft; L is the length of the ship; V r,C is the relative speed of the ocean current.

[0093] The present invention also relates to a current dynamic response analysis system based on the wind-wave-current coupling relationship. The system corresponds to the current dynamic response analysis method based on the wind-wave-current coupling relationship, and can be understood as a system for implementing the above method. The system includes a parameter acquisition and coordinate system establishment module, a power spectrum density calculation module, a first pulsating wind speed model and relationship establishment module, an absolute wind speed calculation module, a current velocity model construction module, and a current interference force calculation module on ships. Specifically,

[0094] The parameter acquisition and coordinate system establishment module acquires sea breeze characteristic parameters, sea wave characteristic parameters and ship motion state parameters under different sea conditions, and establishes a stable coordinate system of the hull with the ship's center of mass as the origin, the ship's motion direction as the longitudinal axis, the starboard side of the ship and parallel to the sea level as the transverse axis, and the center of the earth as the vertical axis; 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 sea wave characteristic parameters include the circular frequency, amplitude and wave number of the wave; the ship's motion state parameters include the ship's speed, waterline length, draft and length;

[0095] 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;

[0096] 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; and establishes an angular frequency interval according to the angular frequency and the bandwidth set based on the angular frequency, and when the angular frequency is within the angular frequency interval, constructs a relationship between the power spectrum density and the amplitude of the fluctuating wind speed;

[0097] The absolute wind speed calculation module obtains a second pulsating wind speed model based on the relationship between the power spectrum density and amplitude of the pulsating wind speed and the first pulsating wind speed model, and then calculates the pulsating wind speed; and calculates the absolute wind speed of the sea breeze according to the pulsating wind speed and the average wind speed at sea level;

[0098] The ocean current velocity model construction module calculates the significant wave height of the waves according to the absolute wind speed of the sea breeze, and calculates the water flow friction speed according to the average wind speed, air density and seawater density at the sea level, and then calculates the flow velocity of the wind-induced current according to the water flow friction speed; and then calculates the flow velocity of the wave-induced current according to the significant wave height, the circular frequency, amplitude and wave number of the waves, and constructs the ocean current velocity model based on the flow velocity of the wind-induced current and the flow velocity of the wave-induced current.

[0099] The module for calculating the interference force of the ocean current on the ship calculates the ocean current velocity according to the ocean current velocity model, and takes the angle between the ocean current flow direction and the navigation direction of the ship as the relative flow angle of the ocean current, and calculates the velocity components of the ocean current in the longitudinal and transverse axis directions according to the ocean current velocity and the relative flow angle in the stable coordinate system of the hull; and calculates the first relative speed of the ship and the ocean current in the longitudinal axis direction according to the velocity component of the ocean current in the longitudinal axis direction and the speed of the ship in the longitudinal axis direction under the condition of no wind and current, and calculates the second relative speed of the ship and the ocean current in the transverse axis direction according to the velocity component of the ocean current in the transverse axis direction and the speed of the ship in the transverse axis direction under the condition of no wind and current; and then calculates the relative speed of the ocean current according to the first relative speed and the second relative speed; and calculates the roll interference force, pitch interference force and heave interference force of the ocean current on the ship according to the relative speed of the ocean current, the waterline length, the draft and the length of the ship.

[0100] Preferably, 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 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.

[0101] Preferably, the ocean wave characteristic parameters also include wavelength, and the wave number is calculated based on the wavelength.

[0102] 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.

[0103] The present invention provides an objective and scientific method and system for analyzing the dynamic response of ocean currents based on the coupling relationship between wind, waves and currents. Based on the characteristic parameters of sea breeze, sea wave characteristics and the motion state parameters of ships under different sea conditions, a pulsating wind speed model is constructed by a specific calculation method to calculate the pulsating wind speed and the significant wave height of ocean waves, and then an ocean current velocity model is constructed. Based on the ocean current velocity model and using a specific calculation method, the interference force (dynamic response) of ocean currents on ships is calculated. By fully considering the mutual influence between sea breeze, waves and ocean currents, the dynamic response of ships in wind, waves and currents can be predicted more accurately, thereby effectively improving the calculation accuracy.

[0104] It should be noted that the above-described specific implementations can enable those skilled in the art to more fully understand the invention, but do not limit the invention in any way. Therefore, although this specification has described the invention in detail with reference to the drawings and embodiments, those skilled in the art should understand that the invention can still be modified or replaced by equivalents. In short, all technical solutions and improvements that do not deviate from the spirit and scope of the invention should be included in the protection scope of the patent for the invention.

Claims

1. A method for analyzing ocean current dynamic response based on wind-wave-current coupling relationship, characterized in that: The following steps are involved: Parameter acquisition and coordinate system establishment steps: obtain sea breeze characteristic parameters, wave characteristic parameters and ship motion state parameters under different sea conditions, and establish a stable coordinate system of the hull with the ship's center of mass as the origin, the ship's motion direction as the longitudinal axis, the starboard side of the ship and the direction parallel to the sea level as the transverse axis, and the center of the earth as the vertical axis; 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 and wave number of the wave; the ship's motion state parameters include the ship's speed, waterline length, draft and length; Power spectrum density calculation steps: calculate 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 calculate 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 step: 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; and establishing an angular frequency interval according to the angular frequency and the bandwidth set based on the angular frequency, and when the angular frequency is within the angular frequency interval, constructing a relationship between the power spectrum density and the amplitude of the fluctuating wind speed; Absolute wind speed calculation steps: 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, and then the fluctuating wind speed is calculated; the absolute wind speed of the sea breeze is calculated according to the fluctuating wind speed and the average wind speed at sea level; The steps of constructing the ocean current velocity model are as follows: the significant wave height of the ocean waves is calculated according to the absolute wind speed of the ocean breeze, and the water friction velocity is calculated according to the average wind speed, air density and seawater density at the sea level, and then the velocity of the wind-induced current is calculated according to the water friction velocity; The velocity of the wave-induced current is calculated based on the significant wave height, circular frequency, wave amplitude and wave number, and the ocean current velocity model is constructed based on the velocity of the wind-induced current and the velocity of the wave-induced current. The steps for calculating the interference force of ocean current on ships are as follows: the ocean current velocity is calculated according to the ocean current velocity model, and the angle between the ocean current flow direction and the ship's sailing direction is taken as the relative flow angle of the ocean current; in the stable coordinate system of the hull, the velocity components of the ocean current in the longitudinal and transverse axis directions are calculated according to the ocean current velocity and the relative flow angle; and the first relative velocity between the ship and the ocean current in the longitudinal axis direction is calculated according to the velocity component of the ocean current in the longitudinal axis direction and the speed of the ship in the longitudinal axis direction under the condition of no wind and current; and the second relative velocity between the ship and the ocean current in the transverse axis direction is calculated according to the velocity component of the ocean current in the transverse axis direction and the speed of the ship in the transverse axis direction under the condition of no wind and current; and then the relative velocity of the ocean current is calculated according to the first relative velocity and the second relative velocity; and the roll interference force, pitch interference force and heave interference force of the ocean current on the ship are calculated according to the relative velocity of the ocean current, the waterline length, the draft and the length of the ship.

2. The method for analyzing ocean current dynamic response based on wind-wave-current coupling relationship according to claim 1 is 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 analyzing ocean current dynamic response based on wind-wave-current coupling relationship according to claim 1 is characterized in that: In the parameter acquisition and coordinate system establishment steps, the wave characteristic parameters also include wavelength, and the wave number is calculated based on the wavelength.

4. The method for analyzing ocean current dynamic response based on wind-wave-current coupling relationship according to claim 1 is 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 current dynamic response analysis system based on wind-wave-current coupling relationship, characterized in that: It includes a parameter acquisition and coordinate system establishment module, a power spectrum density calculation module, a first pulsating wind speed model and relationship establishment module, an absolute wind speed calculation module, an ocean current velocity model construction module, and an ocean current interference force calculation module on ships. The parameter acquisition and coordinate system establishment module acquires sea breeze characteristic parameters, sea wave characteristic parameters and ship motion state parameters under different sea conditions, and establishes a stable coordinate system of the hull with the ship's center of mass as the origin, the ship's motion direction as the longitudinal axis, the starboard side of the ship and parallel to the sea level as the transverse axis, and the center of the earth as the vertical axis; 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 sea wave characteristic parameters include the circular frequency, amplitude and wave number of the wave; the ship's motion state parameters include the ship's speed, waterline length, draft and length; 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; and establishes an angular frequency interval according to the angular frequency and the bandwidth set based on the angular frequency, and when the angular frequency is within the angular frequency interval, constructs a relationship between the power spectrum density and the amplitude of the fluctuating wind speed; The absolute wind speed calculation module obtains a second pulsating wind speed model based on the relationship between the power spectrum density and amplitude of the pulsating wind speed and the first pulsating wind speed model, and then calculates the pulsating wind speed; and calculates the absolute wind speed of the sea breeze according to the pulsating wind speed and the average wind speed at sea level; The ocean current velocity model building module calculates the significant wave height of the ocean waves according to the absolute wind speed of the ocean breeze, and calculates the water flow friction velocity according to the average wind speed, air density and seawater density at the sea level, and then calculates the flow velocity of the wind-induced flow according to the water flow friction velocity; The velocity of the wave-induced current is calculated based on the significant wave height, circular frequency of the wave, amplitude and wave number, and the ocean current velocity model is constructed based on the velocity of the wind-induced current and the velocity of the wave-induced current. The module for calculating the interference force of the ocean current on the ship calculates the ocean current velocity according to the ocean current velocity model, and takes the angle between the ocean current flow direction and the navigation direction of the ship as the relative flow angle of the ocean current, and calculates the velocity components of the ocean current in the longitudinal and transverse axis directions according to the ocean current velocity and the relative flow angle in the stable coordinate system of the hull; and calculates the first relative speed of the ship and the ocean current in the longitudinal axis direction according to the velocity component of the ocean current in the longitudinal axis direction and the speed of the ship in the longitudinal axis direction under the condition of no wind and current, and calculates the second relative speed of the ship and the ocean current in the transverse axis direction according to the velocity component of the ocean current in the transverse axis direction and the speed of the ship in the transverse axis direction under the condition of no wind and current; and then calculates the relative speed of the ocean current according to the first relative speed and the second relative speed; and calculates the roll interference force, pitch interference force and heave interference force of the ocean current on the ship according to the relative speed of the ocean current, the waterline length, the draft and the length of the ship.

6. The ocean current dynamic response analysis system based on wind-wave-current coupling relationship according to claim 5 is 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 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.

7. The ocean current dynamic response analysis system based on wind-wave-current coupling relationship according to claim 5 is characterized in that: The ocean wave characteristic parameters also include wavelength, and the wave number is calculated based on the wavelength.

8. The ocean current dynamic response analysis system based on wind-wave-current coupling relationship according to claim 5 is characterized in that: In the parameter acquisition module, when acquiring 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.

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