A method and system for analyzing ocean current dynamic response based on wind-wave-current coupling relationship

Abstract

The present invention provides a method and system for analyzing the dynamic response of ocean currents based on the coupling relationship between wind, wave and current. A first fluctuating wind speed model is established based on characteristic parameters of ocean breeze, characteristic parameters of ocean waves and motion state parameters of ships under different sea conditions, and a specific calculation method is used to calculate the power spectrum density of the fluctuating wind speed. In the angular frequency range, a relationship between the power spectrum density and amplitude of the fluctuating wind speed is constructed. A second fluctuating wind speed model is then obtained through the relationship and the first fluctuating wind speed model, and the absolute wind speed of the ocean breeze is calculated. The significant wave height of the ocean waves is calculated according to the absolute wind speed, and a specific calculation method is used to calculate the velocities of the wind-induced current and the wave-induced current respectively, 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 of the ocean current on the ship is calculated. By fully considering the mutual influence between ocean breeze, ocean waves and ocean currents, the dynamic response of the ship in wind, wave and current can be more accurately predicted.

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 the wind-wave-current coupling relationship. Background Art

[0002] As a major maritime nation, my country boasts vast maritime territory and a long coastline, surrounded by the Bohai Sea, the Yellow Sea, the East China Sea, and the South China Sea. It boasts over 6,500 islands, approximately 40 billion tons of marine oil and gas, and other abundant marine resources. With its continuous development, my country's marine economy has become a vital component of its overall economy. In 2023, my country's marine GDP reached 9.9097 trillion yuan, accounting for 7.9% of its GDP. Marine industries such as port shipping and shipbuilding play a key role in this. my country boasts a massive maritime transport volume, particularly container transport, ranking first in the world. In 2023, my country held seven of the top ten ports in terms of global throughput. my country's shipbuilding industry continues to lead the world in terms of volume. In 2023, my country's shipbuilding industry held the largest international market share in terms of completions, backlog, and new orders. The industry has successfully delivered numerous large vessels, including 24,000 TEU ultra-large container ships, ultra-large ethylene carriers, and large cruise ships.

[0003] Large ships are affected by the marine environment during ocean voyages, with sea breezes, waves, and currents being the most important environmental factors affecting their movement. Sea breezes refer to the flow of air at sea along the pressure gradient. Waves refer to the fluctuations of seawater in the ocean, where "fluctuation" is the periodic or quasi-periodic movement of water particles away from their equilibrium positions under the action of external forces. Ocean currents refer to the large-scale, relatively stable flow of seawater, where "large-scale, relatively stable flow" means flow with roughly similar direction, velocity, and flow path over large spatial scales and long timeframes. Sea breezes refer to the flow of air at sea along the pressure gradient. As a significant energy source for the global ocean, sea breezes influence the formation of waves and currents.

[0004] Due to my country's vast maritime territory and large shipping volume, some situations necessitate navigation operations in complex marine environments. To ensure the safety and stability of ship navigation and the smooth progress of maritime operations, it is necessary to clarify the mechanism by which the marine environment affects the motion of large ships. The marine environment primarily impacts ships through the effects of sea breezes, waves, and currents. Because the characteristics of sea breezes, waves, and currents vary in different sea conditions, their disturbing effects on ships are also different. By varying the characteristic parameters of sea breezes, waves, and currents, we study their impact on the disturbed motion of ships, thereby providing a reference for safety analysis and recommendations for navigation missions.

[0005] In summary, the complex coupling relationships among wind, waves, and currents in the ocean environment influence each other. This makes it difficult to simulate wind, wave, and current based on their generation mechanisms. Furthermore, current methods for calculating disturbance forces in studies of ship disturbances fail to fully account for the impact of wind-wave-current interactions on ships, and thus fail to realistically describe the wind-wave-current environment under varying sea conditions. Summary of the Invention

[0006] The present invention addresses the problems existing in current research on the disturbance effects of ships, such as the failure to consider the interaction between sea breeze, waves, and currents, and the inability to truly simulate the wind, wave, and current environment under different sea conditions. The present invention provides a method for analyzing the dynamic response of ocean currents based on the wind-wave-current coupling relationship. Based on the characteristic parameters of sea breeze and waves under different sea conditions, as well as the motion state parameters of the ship, a specific calculation method is used to construct a fluctuating wind speed model to calculate the fluctuating wind speed and the significant wave height of the waves. Furthermore, an ocean current velocity model is constructed. Based on the ocean current velocity model and a specific calculation method, the disturbance 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. The present invention also relates to an ocean current dynamic response analysis system based on the wind-wave-current coupling relationship.

[0007] The technical solutions of the present invention are as follows:

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

[0009] Parameter acquisition and coordinate system establishment steps: acquiring sea breeze characteristic parameters, wave characteristic parameters and ship motion state parameters under different sea conditions, and establishing a hull stable coordinate system with the ship's center of mass as the origin, the ship's motion direction as the longitudinal axis, the direction of the ship's starboard side 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 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;

[0010] 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;

[0011] 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;

[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 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;

[0013] The steps for constructing the ocean current velocity model are as follows: the significant wave height of the ocean waves is calculated based on the absolute wind speed of the sea breeze, and the water friction velocity is calculated based on the average wind speed, air density, and seawater density at sea level. The velocity of the wind-induced current is then calculated based on the water friction velocity. The velocity of the wave-induced current is then calculated based on the significant wave height, circular frequency, amplitude, and wave number of the waves. 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: calculate the ocean current velocity according to the ocean current velocity model, and take the angle between the ocean current flow direction and the ship's navigation direction as the relative flow angle of the ocean current; in the stable coordinate system of the hull, calculate the velocity components of the ocean current in the longitudinal and transverse axis directions respectively according to the ocean current velocity and the relative flow angle; and calculate the first relative velocity 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 conditions of no wind and current; calculate the second relative velocity 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 conditions of no wind and current; then calculate the relative velocity of the ocean current according to the first relative velocity and the second relative velocity; and calculate the roll interference force, pitch interference force and heave interference force of the ocean current on the ship respectively according to the relative velocity of the ocean current, the waterline length, draft and 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 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.

[0018] A current dynamic response analysis system based on the wind-wave-current coupling relationship is characterized by comprising a parameter acquisition and coordinate system establishment module, a power spectrum density calculation module, a first fluctuating 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.

[0019] The parameter acquisition and coordinate system establishment module acquires sea breeze characteristic parameters, 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 direction of the ship's starboard side 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 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;

[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; 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;

[0022] The 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;

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

[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. In the stable coordinate system of the hull, the module 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; and calculates the first relative velocity 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 conditions of no wind and current, and calculates the second relative velocity 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 conditions of no wind and current; and then calculates the relative velocity of the ocean current according to the first relative velocity and the second relative velocity; and calculates the roll interference force, pitch interference force and heave interference force of the ocean current on the ship according to the relative velocity of the ocean current, the waterline length, draft and length of the ship.

[0025] 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.

[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 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.

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

[0029] The present invention provides a method for analyzing ocean current dynamic response based on the wind-wave-current coupling relationship. The method calculates the power spectrum density of the fluctuating wind speed based on the characteristic parameters of the sea breeze and the characteristic parameters of the sea waves under different sea conditions and adopts a specific calculation method, which can effectively reveal the energy distribution of the 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 in 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 degree to which different frequency components contribute 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 sea breeze is calculated The significant wave height of the waves is obtained, and the influence of wind speed on the waves is fully considered, which is helpful to comprehensively evaluate the effect of wind on the wave shape of 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 speed of wind-induced current is calculated according to the water friction speed, which can more comprehensively describe the influence of wind on seawater movement; the speed of wave-induced current is calculated according to the significant wave height, circular frequency, amplitude and wave number of waves, which can more comprehensively describe the influence of waves on ocean currents; based on the speed of wind-induced current and the speed of wave-induced current, an ocean current velocity model is constructed, and finally, based on the ocean current velocity model and a specific calculation method, the roll interference force, pitch interference force and heave interference force (dynamic response) of the ocean current on the ship are calculated. By fully considering the interaction between sea breeze, waves and ocean currents, the dynamic response of the ship in wind, wave and current can be predicted more accurately, which effectively improves the calculation accuracy and is of great significance for understanding and responding to complex marine environments.

[0030] 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 above-mentioned current dynamic response analysis method based on the wind-wave-current coupling relationship, and can be understood as a system that implements the above-mentioned current dynamic response analysis method based on the wind-wave-current coupling relationship, including a parameter acquisition module, a power spectrum density calculation module, a first fluctuating wind speed model and relationship establishment module, an absolute wind speed calculation module and a current velocity model construction 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 using a specific calculation method to construct a fluctuating wind speed model to calculate the fluctuating wind speed and the significant wave height of the waves, and then construct a current velocity model. Based on the current velocity model and using a specific calculation method, the interference force (dynamic response) of the current on the ship is calculated. By fully considering the interaction between the sea breeze, waves and currents, the dynamic response of the ship in the wind, wave and current can be predicted more accurately, 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 stable coordinate system of the present invention. DETAILED DESCRIPTION

[0033] The present invention will be described below with reference to the accompanying drawings.

[0034] The present invention relates to a method for analyzing ocean current dynamic response based on the 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 direction of the ship's starboard side 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 related 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 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 the ship's motion is the longitudinal axis, that is, Ox s The axis points to the direction of the ship's movement, 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, that is, 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 characteristic parameter of the ocean wave also includes 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.

[0037] 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.

[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 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.

[0041] 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.

[0042] 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:

[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 fluctuating 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, +∞], but in actual simulations, 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, 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:

[0050]

[0051] Where 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, 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.

[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 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:

[0057]

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

[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 the Froude number is:

[0067]

[0068] The recommended calculation formula for height z 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 friction speed u *w Calculate the velocity of wind-induced flow according to the following formula:

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

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

[0076]

[0077] Where 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: calculate the ocean current velocity according to the ocean current velocity model, and take the angle between the ocean current flow direction and the ship's navigation direction as the relative flow angle of the ocean current; in the stable coordinate system of the hull, calculate the velocity components of the ocean current in the longitudinal and transverse axis directions respectively according to the ocean current velocity and the relative flow angle; and calculate the first relative velocity 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 conditions of no wind and current; calculate the second relative velocity 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 conditions of no wind and current; then calculate the relative velocity of the ocean current according to the first relative velocity and the second relative velocity; and calculate the roll interference force, pitch interference force and heave interference force of the ocean current on the ship respectively according to the relative velocity of the ocean current, the waterline length, draft and length of the ship.

[0081] Specifically, first calculate the ocean current velocity V according to the ocean current velocity model: C The angle between the ocean current flow direction and the ship's navigation 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 Calculate the velocity components of the ocean current in the longitudinal axis (i.e., x-axis) and the transverse axis (i.e., y-axis) directions respectively, and calculate them 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) direction C , and under the conditions of no wind and current, the ship's speed u in the longitudinal axis direction is calculated to obtain the first relative speed u between the ship and the current in the longitudinal axis direction r ; or according to the velocity component u of the ocean current in the longitudinal direction C , the velocity component v of the ocean current in the transverse axis direction C , and under the conditions of no wind and current, the ship's speed u in the longitudinal axis direction is calculated to obtain the first relative speed u between the ship and the current in the longitudinal axis (x axis) direction r , calculated according to the following formula:

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

[0086] And according to the velocity component v of the ocean current in the transverse axis (ie y axis) direction C , and under the conditions of no wind and current, the ship's speed v in the longitudinal axis direction is used to calculate the second relative speed v between the ship and the current in the longitudinal axis direction r ; or according to the velocity component u of the ocean current in the longitudinal direction C , the velocity component v of the ocean 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 sinχ C +v C cosχ 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 roll disturbance force coefficient, pitch disturbance force coefficient, and heave 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 ship's length; 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 above-mentioned current dynamic response analysis method based on the wind-wave-current coupling relationship and can be understood as a system for implementing the above-mentioned method. The system includes a parameter acquisition and coordinate system establishment module, a power spectrum density calculation module, a first fluctuating 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, 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 direction of the ship's starboard side 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 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;

[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; 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;

[0097] The 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;

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

[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. In the stable coordinate system of the hull, the module 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; and calculates the first relative velocity 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 conditions of no wind and current, and calculates the second relative velocity 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 conditions of no wind and current; and then calculates the relative velocity of the ocean current according to the first relative velocity and the second relative velocity; and calculates the roll interference force, pitch interference force and heave interference force of the ocean current on the ship according to the relative velocity of the ocean current, the waterline length, draft and length of the ship.

[0100] 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.

[0101] Preferably, the ocean wave characteristic parameter also includes 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 ocean current dynamic response analysis method and system based on the wind-wave-current coupling relationship. Based on the sea breeze characteristic parameters, wave characteristic parameters and ship motion state parameters under different sea conditions, a specific calculation method is used to construct a pulsating wind speed model to calculate the pulsating 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 using a specific calculation method, the interference force (dynamic response) of the current on the ship is calculated. By fully considering the mutual influence between sea breeze, waves and currents, the dynamic response of the ship in wind, waves and currents can be predicted more accurately, effectively improving the calculation accuracy.

[0104] 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 analyzing ocean current dynamic response based on wind-wave-current coupling, characterized in that: The following steps are involved: Parameter acquisition and coordinate system establishment steps: acquiring sea breeze characteristic parameters, wave characteristic parameters and ship motion state parameters under different sea conditions, and establishing a hull stable coordinate system with the ship's center of mass as the origin, the ship's motion direction as the longitudinal axis, the direction of the ship's starboard side 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 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; 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; 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 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 constructing the ocean current velocity model are as follows: the significant wave height is calculated based on the absolute wind speed of the sea breeze, and the water friction velocity is calculated based on the average wind speed, air density and seawater density at the sea level. The velocity of the wind-induced current is then calculated based on the water friction velocity. The velocity of the wave-induced current is then calculated based on the significant wave height, circular frequency, amplitude, and wave number, and a 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: calculate the ocean current velocity according to the ocean current velocity model, and take the angle between the ocean current flow direction and the ship's navigation direction as the relative flow angle of the ocean current; in the stable coordinate system of the hull, calculate the velocity components of the ocean current in the longitudinal and transverse axis directions respectively according to the ocean current velocity and the relative flow angle; and calculate the first relative velocity 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 conditions of no wind and current; calculate the second relative velocity 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 conditions of no wind and current; then calculate the relative velocity of the ocean current according to the first relative velocity and the second relative velocity; and calculate the roll interference force, pitch interference force and heave interference force of the ocean current on the ship respectively according to the relative velocity of the ocean current, the waterline length, draft and length of the ship.

2. The ocean current dynamic response analysis method 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 ocean current dynamic response analysis method 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 ocean current dynamic response analysis method 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 connected in sequence. The parameter acquisition and coordinate system establishment module acquires sea breeze characteristic parameters, 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 direction of the ship's starboard side 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 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; 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 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 ocean current velocity model construction module calculates the significant wave height of the ocean waves based on the absolute wind speed of the sea breeze, and calculates the water friction velocity based on the average wind speed, air density and seawater density at the sea level, and then calculates the flow velocity of the wind-induced flow based on the water friction velocity; The velocity of the wave-induced current is then calculated based on the significant wave height, circular frequency, amplitude, and wave number, and a 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. In the stable coordinate system of the hull, the module 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; and calculates the first relative velocity 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 conditions of no wind and current, and calculates the second relative velocity 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 conditions of no wind and current; and then calculates the relative velocity of the ocean current according to the first relative velocity and the second relative velocity; and calculates the roll interference force, pitch interference force and heave interference force of the ocean current on the ship according to the relative velocity of the ocean current, the waterline length, draft and 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 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 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 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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