Analysis Method and System for Ship Wind and Wave Loads and Dynamic Response under Short Peak Wave State

Abstract

This invention provides a method and system for analyzing ship wind and wave loads and dynamic response under short-peak wave sea states. Based on the characteristic parameters of wind and waves under different sea states and the ship's motion parameters, a long-peak wave model is established. The first wave surface equation is calculated in ground coordinates, and then transformed to the ship's stable coordinate system using coordinate and frequency transformation methods to obtain a second wave surface equation applicable to the ship's surrounding environment. A wave pressure model caused by the waves is then established and corrected using the exponential decay method. Finally, a multi-wave superimposed wave pressure model is obtained through coordinate and frequency transformation methods and harmonic superposition analysis. Specific calculation methods are used to calculate the disturbance force and disturbance torque, enabling more accurate prediction of the ship's dynamic response in wind and waves and more accurate assessment of the take-off and landing safety of shipborne helicopters under high sea state conditions, effectively improving calculation accuracy.

Description

Technical Field

[0001] This invention relates to the field of shipbuilding and marine engineering technology, specifically to a method and system for analyzing ship wind and wave loads and dynamic response under short-peak wave sea conditions. Background Technology

[0002] In modern naval warfare, air power has become an indispensable and crucial support for naval vessels. With the continuous development and expansion of my country's navy in recent years, its demand for shipborne aviation power has also been gradually increasing. At the same time, the maturity of shipborne helicopter technology and the continuous development of new vertical takeoff and landing aircraft have given frigates, destroyers, and other non-through-deck ships an increasingly important position in the field of shipborne aviation power delivery.

[0003] However, the marine environment, dominated by wind, waves, and changing weather, and the shipboard environment, dominated by wake currents and deck disturbances, directly affect the flight performance of shipborne helicopters and other aircraft, and may even directly endanger flight safety. Especially in high sea states, due to the violent rolling of the ship and the adverse flow environment, shipborne helicopters and other aircraft often struggle to perform take-off and landing missions normally, posing a severe challenge to shipborne air combat capabilities.

[0004] Current technologies have limitations in addressing these issues. For example, traditional wind and wave models and ship motion models do not fully consider the dynamic characteristics of wind and waves, such as wave amplitude, wave number, and propagation direction. This results in an imprecise description of wind and wave behavior, making it impossible to accurately predict the dynamic response of ships in high sea states and hindering the accurate assessment of the safety of shipborne helicopter takeoffs and landings. Furthermore, existing methods for calculating wave pressure neglect nonlinear effects and the interaction between wind and waves, leading to inaccurate calculations of disturbance forces and moments, which affect the safety and reliability of ship design. Moreover, existing methods for calculating disturbance forces and moments fail to adequately consider the impact of wind and waves on ships, thus affecting the assessment of the safety of shipborne helicopter takeoffs and landings.

[0005] Therefore, there is an urgent need for a method that can accurately predict the dynamic response of ships and its impact on the take-off and landing of shipborne helicopters under complex sea conditions, so as to improve the safety and efficiency of shipborne aviation operations. Summary of the Invention

[0006] This invention addresses the shortcomings of current methods for analyzing ship wind and wave loads and dynamic responses in complex sea states, including imprecise descriptions of wave behavior, inaccurate calculation results, and insufficient consideration of the impact of waves on ships. It provides a method for analyzing ship wind and wave loads and dynamic responses in short-peak wave (SWP) sea states. Based on characteristic parameters of the waves and the ship's motion parameters, a SWP wind and wave model is established. Specific calculation and coordinate transformation methods are used to obtain the wave surface equation, and a multi-wave superposition wave pressure model (wind and wave load) is obtained through specific correction methods. The disturbance force and disturbance torque (dynamic response) are then calculated, enabling more accurate prediction of the ship's dynamic response in wind and waves and a more accurate assessment of the take-off and landing safety of shipborne helicopters under high sea state conditions, effectively improving calculation accuracy. This invention also relates to a system for analyzing ship wind and wave loads and dynamic responses in SWP sea states.

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

[0008] A method for analyzing ship wind and wave loads and dynamic response under short-peak wave sea states, characterized by comprising the following steps:

[0009] Steps for parameter acquisition and coordinate system establishment: Acquire wind and wave characteristic parameters and ship motion state parameters under different sea states, and establish a ground coordinate system with any point on the sea surface as the origin, the ship's motion direction as the abscissa, the ship's starboard side parallel to the sea surface as the ordinate, and the geocenter as the vertical coordinate; establish a ship stability coordinate system with the ship's center of mass as the origin, the ship's motion direction as the abscissa, the ship's starboard side parallel to the sea surface as the ordinate, and the geocenter as the vertical coordinate; the wind and wave characteristic parameters include wave amplitude, wave number, main propagation direction of wind and waves, propagation direction of wind and wave harmonics, wind and wave angular frequency, time of wind and wave morphology transformation, natural period of wind and waves, and natural wave speed; the ship's motion state parameters include ship speed, encounter period, and encounter angular frequency.

[0010] Steps for constructing a short crest wave model: In the ground coordinate system, establish a plane wave equation about the wave height based on wave amplitude, wave number, main propagation direction of wind and waves, propagation direction of wind and wave harmonics, and time of wind and wave morphology transformation. Then, recursively derive the short crest wave model based on the plane wave equation.

[0011] Wave surface equation and wave height calculation steps: Calculate the directional spectrum of short-crest waves based on the propagation direction of wind and wave harmonics. Then, in ground coordinates, construct a first expression for the energy of long-crest waves based on wave amplitude and seawater density. Establish an angular frequency range based on the wind and wave angular frequency and the bandwidth set according to the wind and wave angular frequency, and obtain a second expression for the energy of long-crest waves within the angular frequency range. From the second expression, derive a third expression for the energy spectrum of long-crest waves, and then calculate the energy spectrum of long-crest waves. Calculate the short-crest wave wind and wave spectrum based on the directional spectrum of short-crest waves and the energy spectrum of long-crest waves. Establish a fourth expression for the energy of short-crest waves based on the short-crest wave wind and wave spectrum. Calculate the first expression for the energy of short-crest waves using the fourth expression and the short-crest wave wind and wave model. First, a wave surface equation is established. Then, a first relationship between the encounter period and the encounter angular frequency is established, and the angle between the ship's speed direction and the main propagation direction of the wind and waves is taken as the ship's encounter angle. Based on the ship's encounter angle, the natural period of the wind and waves, the natural wave speed of the wind and waves, and the ship's speed, a second relationship about the encounter period is established. Based on the ship's encounter angle, the wind and waves angular frequency, the natural wave speed of the wind and waves, and the ship's speed, a third relationship about the encounter angular frequency is established. Based on the first, second, and third relationships, and using coordinate and frequency transformation methods, the first wave surface equation located in the ground coordinate system is transformed into the ship's stable coordinate system to obtain a second wave surface equation applicable to the ship's surrounding environment. The wave height encountered by the ship during navigation is calculated based on the second wave surface equation.

[0012] Steps for obtaining the multi-wave superposition wave pressure model: In the ship's stable coordinate system, calculate the sea surface depth of a certain point underwater from the free surface based on the liquid surface depth under still water conditions and the wave height encountered by the ship during navigation. Construct a fifth expression for the pressure at a certain point underwater based on the sea surface depth and atmospheric pressure. Calculate a sixth expression for the pressure at a certain point underwater under short-crest wave conditions based on the fifth expression and the short-crest wave model. Obtain the wave pressure model caused by the waves based on the sixth expression, and correct the wave pressure model using the Smith correction term method to obtain the corrected wave pressure model. Finally, express the corrected wave pressure model as the superposition of multiple cosine waves using the harmonic superposition analysis method to obtain the multi-wave superposition wave pressure model.

[0013] The calculation steps for interference force and interference moment are as follows: The wave pressure experienced by the ship is calculated based on the multi-wave superposition wave pressure model. Then, based on the Froude-Krylov assumption and the prismatic ship assumption, the wave pressure experienced by the ship is integrated at the bottom of the ship to obtain the heave interference force. Next, the heave interference force is integrated along the direction of the ship's pitch axis to obtain the pitch interference moment experienced by the ship in the pitch direction. The heave interference force is then integrated along the bottom, left, and right directions of the ship's roll axis to obtain the bottom, left, and right side components of the roll interference moment experienced by the ship in the roll direction. Finally, the roll interference moment is calculated based on these components to complete the analysis of the ship's wind and wave load and dynamic response.

[0014] Preferably, in the wave surface equation and wave height calculation steps, when the bandwidth in the third expression approaches zero, the integral expression of the long-peak wave energy is calculated based on the first and third expressions, and the relationship between the wave harmonic amplitude and the spectral density function is calculated based on the integral expression.

[0015] Preferably, in the parameter acquisition and coordinate system establishment steps, the wind and wave characteristic parameters further include wavelength, and the wave number is calculated based on the wavelength.

[0016] Preferably, the coordinate and frequency transformation method includes coordinate transformation based on a rotation matrix and transformation from wave frequency to encounter frequency.

[0017] A system for analyzing ship wind and wave loads and dynamic response under short-peak wave sea states is characterized by comprising, in sequence, a parameter acquisition and coordinate system establishment module, a short-peak wave model construction module, a wave surface equation and wave height calculation module, a multi-wave superposition wave pressure model acquisition module, and a disturbance force and disturbance torque calculation module.

[0018] The parameter acquisition and coordinate system establishment module acquires wind and wave characteristic parameters and ship motion state parameters under different sea states, and establishes a ground coordinate system with any point on the sea surface as the origin, the ship's motion direction as the abscissa, the ship's starboard side parallel to the sea surface as the ordinate, and the Earth's center as the vertical coordinate; and establishes a ship stability coordinate system with the ship's center of mass as the origin, the ship's motion direction as the abscissa, the ship's starboard side parallel to the sea surface as the ordinate, and the Earth's center as the vertical coordinate; the wind and wave characteristic parameters include wave amplitude, wave number, main propagation direction of wind and waves, propagation direction of wind and wave harmonics, wind and wave angular frequency, time of wind and wave morphology transformation, natural period of wind and waves, and natural wave speed; the ship's motion state parameters include ship speed, encounter period, and encounter angular frequency.

[0019] The short crest wave model construction module establishes a plane wave equation about the wave height in the ground coordinate system based on wave amplitude, wave number, main propagation direction of wind and waves, propagation direction of wind and wave harmonics, and time of wind and wave morphology transformation, and then recursively obtains the short crest wave model based on the plane wave equation.

[0020] The wave surface equation and wave height calculation module calculates the directional spectrum of short-crest waves based on the propagation direction of wind and wave harmonics. In ground coordinates, it constructs a first expression for the energy of long-crest waves based on wave amplitude and seawater density. It establishes an angular frequency range based on the wind and wave angular frequency and a bandwidth set accordingly, thus obtaining a second expression for the energy of long-crest waves within this range. From the second expression, a third expression for the energy spectrum of long-crest waves is recursively derived, and the energy spectrum of long-crest waves is calculated. Based on the directional spectrum of short-crest waves and the energy spectrum of long-crest waves, the wind and wave spectrum of short-crest waves is calculated. A fourth expression for the energy of short-crest waves is established based on this spectrum. The wind and wave spectrum of short-crest waves is then calculated using the fourth expression and the short-crest wave model. The first wave surface equation is then established; a first relationship between the encounter period and the encounter angular frequency is established, and the angle between the ship's speed direction and the main propagation direction of the wind and waves is taken as the ship's encounter angle. Based on the ship's encounter angle, the natural period of the wind and waves, the natural wave speed of the wind and waves, and the ship's speed, a second relationship about the encounter period is established, and based on the ship's encounter angle, the wind and waves angular frequency, the natural wave speed of the wind and waves, and the ship's speed, a third relationship about the encounter angular frequency is established. Based on the first, second, and third relationships, and using coordinate and frequency transformation methods, the first wave surface equation located in the ground coordinate system is transformed into the ship's stable coordinate system to obtain the second wave surface equation applicable to the ship's surrounding environment. The wave height encountered by the ship during navigation is then calculated based on the second wave surface equation.

[0021] The multi-wave superposition wave pressure model acquisition module calculates the sea surface depth of a point underwater from the free surface based on the liquid surface depth under still water conditions and the wave height encountered by the ship during navigation in the ship's stable coordinate system. It then constructs a fifth expression for the pressure at that point underwater based on the sea surface depth and atmospheric pressure. Next, it calculates a sixth expression for the pressure at that point underwater under short-crest wave conditions based on the fifth expression and the short-crest wave model. Finally, it obtains a wave pressure model caused by waves based on the sixth expression and corrects it using the Smith correction term method to obtain the corrected wave pressure model. Finally, it uses harmonic superposition analysis to represent the corrected wave pressure model as a superposition of multiple cosine waves, thus obtaining a multi-wave superposition wave pressure model.

[0022] The interference force and interference moment calculation module calculates the wave pressure on the ship based on the multi-wave superposition wave pressure model, and performs integration calculation on the wave pressure on the ship's bottom based on the Froude-Krylov assumption and the prismatic ship assumption to obtain the heave interference force of the ship; then, it integrates the heave interference force along the direction of the ship's pitch axis to obtain the pitch interference moment of the ship in the pitch direction; it integrates the heave interference force along the bottom, left, and right directions of the ship's roll axis to obtain the bottom, left, and right side components of the roll interference moment of the ship in the roll direction; and finally, it calculates the roll interference moment based on the bottom, left, and right side components of the roll interference moment to complete the analysis of the ship's wind and wave load and dynamic response.

[0023] Preferably, in the wave surface equation and wave height calculation module, when the bandwidth in the third expression approaches zero, the integral expression of the long-peak wave energy is calculated based on the first and third expressions, and the relationship between the wave harmonic amplitude and the spectral density function is calculated based on the integral expression.

[0024] Preferably, in the parameter acquisition and coordinate system establishment step module, the wind and wave characteristic parameters also include wavelength, and the wave number is calculated based on the wavelength.

[0025] Preferably, the coordinate and frequency transformation method includes coordinate transformation based on a rotation matrix and transformation from wave frequency to encounter frequency.

[0026] The beneficial effects of this invention are as follows:

[0027] This invention provides a method for analyzing ship wind and wave loads and dynamic response under short-peak wave (SBC) sea states. Based on the characteristic parameters of wind and waves under different sea states and the ship's motion parameters, it establishes a SBC wind and wave model that includes multiple characteristic parameters such as wave amplitude, wave number, main propagation direction of wind and waves, and propagation direction of wind and wave harmonics. This model can more accurately and quickly describe the behavior of wind and waves and their impact on ships, improving the accuracy of the model. Furthermore, based on the established ground coordinate system and ship stability coordinate system, the wind and wave model is transformed from the ground coordinate system to the ship coordinate system through coordinate and frequency transformation methods, which can more accurately reflect the actual motion state of the ship in the waves. Then, by using specific calculation methods and constructed expressions and relationships, a second wave surface equation applicable to the ship's surrounding environment is calculated. Based on the second wave surface equation, the wave height encountered by the ship during navigation is calculated, which can more accurately reflect the actual wave conditions, especially for accurate wave height prediction under complex sea states, reducing the risk of ships encountering extreme sea states. To protect the safety of ships and their crews, the Smith correction method is used to modify the wave pressure model obtained from the established expressions, resulting in a modified wave pressure model to improve calculation accuracy and effectively and accurately assess the forces acting on ships in wind and waves. Furthermore, a multi-wave superposition wave pressure model is obtained through harmonic superposition analysis. This model considers pressure changes at a specific underwater point, the interaction between wind and waves, and nonlinear effects, effectively improving the accuracy and reliability of wave pressure calculations and making predictions of ship dynamic responses more accurate. Finally, based on the calculated wave pressure acting on the ship, specific calculation methods are used to calculate the heave disturbance force and the pitch and roll disturbance moments. By fully considering the influence of wind and waves on the pressure distribution on the ship's surface, the force distribution acting on the ship in wind and waves can be better understood, enabling a more accurate assessment of the take-off and landing safety of shipborne helicopters under high sea states. This is of great significance for ensuring the safe take-off and landing of shipborne helicopters under high sea states. This invention can effectively improve the take-off and landing capabilities and safety of shipborne aircraft under complex sea states, thereby enhancing the overall combat effectiveness of shipborne aviation forces.

[0028] This invention also relates to a system for analyzing ship wind and wave loads and dynamic response under short crest wave sea states. This system corresponds to the aforementioned method for analyzing ship wind and wave loads and dynamic response under short crest wave sea states. It can be understood as a system that implements the aforementioned method for analyzing ship wind and wave loads and dynamic response under short crest wave sea states. The system includes a parameter acquisition and coordinate system establishment module, a long crest wave model construction module, a wave surface equation and wave height calculation module, a multi-wave superposition wave pressure model acquisition module, and an interference force and interference moment calculation module, which are connected in sequence. Each module works together to establish a short crest wave wind and wave model based on the characteristic parameters of wind and waves and the motion state parameters of the ship. The wave surface equation is obtained by using specific calculation methods and coordinate transformation methods, and the multi-wave superposition wave pressure model (wind and wave load) is obtained by using specific correction methods. Then, the interference force and interference moment (dynamic response) are calculated. This system can more accurately predict the dynamic response of the ship in wind and waves and can more accurately assess the take-off and landing safety of shipborne helicopters under high sea state conditions, effectively improving the calculation accuracy. Attached Figure Description

[0029] Figure 1 This is a flowchart of the method for analyzing ship wind and wave loads and dynamic response under short-peak wave sea conditions according to the present invention.

[0030] Figure 2 This is a schematic diagram of the ground coordinate system of the present invention.

[0031] Figure 3 This is a schematic diagram of the ship hull stability coordinate system of the present invention.

[0032] Figure 4 This is a schematic diagram of the planar wave waveform of the present invention.

[0033] Figure 5 This is a schematic diagram of the ship of the present invention sailing in wind and waves.

[0034] Figure 6 This is a schematic diagram of the force analysis on the bottom surface of the hull of the present invention.

[0035] Figure 7 This is a schematic diagram of the force analysis on the side of the hull of the present invention. Detailed Implementation

[0036] The present invention will now be described with reference to the accompanying drawings.

[0037] This invention relates to a method for analyzing the wind and wave loads and dynamic response of ships under short-peak wave sea states. The flowchart of this method is shown below. Figure 1 As shown, the steps are as follows:

[0038] Steps for parameter acquisition and coordinate system establishment: Acquire wind and wave characteristic parameters and ship motion state parameters under different sea states, and establish a ground coordinate system with any point on the sea surface as the origin, the ship's motion direction as the longitudinal axis, the ship's starboard side parallel to the sea surface as the transverse axis, and the Earth's center as the vertical axis; establish a ship stability coordinate system with the ship's center of mass as the origin, the ship's motion direction as the longitudinal axis, the ship's starboard side parallel to the sea surface as the transverse axis, and the Earth's center as the vertical axis; the wind and wave characteristic parameters include wave amplitude, wave number, main propagation direction of wind and waves, propagation direction of wind and wave harmonics, wind and wave angular frequency, time of wind and wave shape transformation, natural period of wind and waves, and natural wave speed; the ship's motion state parameters include ship speed, encounter period, and encounter angular frequency.

[0039] Specifically, the ground coordinate system E-ξηζ is as follows: Figure 2 As shown, this is a fixed inertial coordinate system anchored to the earth, used to describe the motion of ocean waves. The origin E can be any point on the sea level. The Earth's center is the vertical axis (Eζ axis points to the Earth's center), the ship's direction of motion is the longitudinal axis (Eξ axis points to the ship's direction of motion), and the ship's starboard side, parallel to the sea level, is the transverse axis (Eη axis points to the ship's starboard side, parallel to the sea level). The Eξ and Eη axes are located within the sea level and are perpendicular to each other. The distribution of the three coordinate axes conforms to the right-hand rule. (Ship stability coordinate system Ox) s y s z s like Figure 3 As shown, this is a coordinate system that moves with the ship, used to describe the motion of the ship's hull in a stable state. The origin O of the coordinate system is the ship's center of mass, and the direction of the ship's motion is the longitudinal axis, i.e., Ox. s The axis points in the direction of the ship's movement; the direction on the ship's starboard side, parallel to the sea level, is the transverse axis, i.e., Oy. s The direction pointing to the starboard side of the ship and parallel to the sea level, with the Earth's center as the vertical axis, i.e., Oz s The axis points to the Earth's center, 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.

[0040] Steps for constructing a short crest wave model: In the ground coordinate system, establish a plane wave equation about the wave height based on wave amplitude, wave number, main propagation direction of wind and waves, propagation direction of wind and wave harmonics, and time of wind and wave morphology transformation. Then, recursively derive the short crest wave model based on the plane wave equation.

[0041] During navigation in high sea states, ships are subject to various disturbances from the marine environment, such as waves, wind, and currents. Random waves are the most significant disturbance factor. Therefore, understanding the distribution of random waves under high sea states is essential before analyzing the ship's motion. Specifically, wave simulation has always been a highly complex problem. In reality, wind and waves on the sea surface are extremely complex, irregular, random three-dimensional waves, making accurate wave modeling very difficult. However, current research on ship motion considers that wind and waves generally propagate unidirectionally along the wind direction, i.e., only along their main propagation direction (i.e., the ξ axis in the ground coordinate system). Therefore, it can be assumed that wave crests and troughs are parallel to each other and perpendicular to the wave propagation direction. In this case, if the main propagation direction of the wind and waves is the ξ axis, then the wave height (wave surface height) ζ at a fixed point on the sea surface is expressed as a bivariate function of ξ and time t: ζ = ζ(ξ, t). According to the Longuet-Higgins model, the long-peaked wave model of irregular wind waves can be considered as the superposition of countless planes with different amplitudes, wavelengths, and initial phases within the plane perpendicular to the main propagation direction of the wind waves. This is based on the following fluid dynamics assumptions:

[0042] a) The fluid is incompressible;

[0043] b) Fluids possess only potential velocity;

[0044] c) The waves are minor.

[0045] A plane wave propagating along the ξ-axis can be represented as:

[0046] ζ=ζ a cos(kξ-ωt) (1)

[0047] Where ζ is the wave height (also known as the distance the wave surface deviates from the sea level, or the height of the wave surface relative to the average sea level); ζ a ω represents wave amplitude; k represents wave number; λ represents wavelength, which is related to wave number: k = 2π / λ; ω represents the angular frequency of the wind and waves. t represents the time of change in the angular frequency and shape of the wind and waves, describing the change of the wind and waves over time. At t = 0, the wave pattern of its plane progressive wave is as follows: Figure 4 As shown.

[0048] Based on the plane wave formula, the long-crested wave model (also known as the Longuet-Higgins model of long-crested waves) can be derived, as shown in the following equation:

[0049]

[0050] Where, k i ω i , ζ aiThese represent the wave number, wind and wave angular frequency, and wave amplitude of the i-th harmonic, respectively; ε i The i-th harmonic is a random initial phase between 0 and 2π.

[0051] However, the aforementioned long-crest wave model, which only considers the main propagation direction of the wind wave as the ξ-axis, still suffers from problems such as inaccurate capture of wave propagation characteristics and slow computation speed. Therefore, a short-crest wave model is introduced. This model assumes that different harmonics of the wind wave propagate along different propagation angles μ. μ is defined as 0 when propagating along the ξ-axis, and positive when rotating around the ζ-axis using the right-hand rule. Therefore, in the short-crest wave model, the wave height ζ at a fixed point on the sea surface should be expressed as a ternary function ζ = ζ(ξ, η, t) of ξ, η, and time t. The equations for a plane wave propagating at a propagation angle μ are rewritten in the three-dimensional ground coordinate system E-ξηζ as follows:

[0052] ζ=ζ a cos[k(ξcosμ j -ηsinμ j )-ωt] (3)

[0053] Where, ζ a Let denot be the wave amplitude, k be the wave number, ζ be the wave height, μ be the propagation angle, and the propagation directions of different harmonics of the wind and waves are along different propagation angles μ. The main propagation directions of the wind and waves are along the ξ axis and the η axis, and ω is the angular frequency of the wind and waves.

[0054] Based on the wave equations of the plane, the short-crest wave model (also known as the Longuet-Higgins model of short-crest waves) is derived as follows:

[0055]

[0056] The short-crest wave model considers the main propagation directions of wind and waves along the ξ and η axes, and introduces the propagation direction of wind and wave harmonics along different propagation angles μ. This allows the short-crest wave model to more accurately capture the propagation characteristics of ocean waves (including the propagation direction and energy distribution of wind and waves). Furthermore, because the short-crest wave model includes more degrees of freedom, it can more meticulously characterize the irregularities of ocean waves, thereby improving the accuracy of predictions. This is crucial for the study of wave dynamics, marine engineering design, and safety assessment. Simultaneously, the short-crest wave model is applicable to various complex marine environments, including wave conditions under different sea areas, seasons, and weather conditions. It can better simulate real-world wind and wave behavior, providing a more reliable foundation for scientific research and engineering practice in related fields.

[0057] Wave surface equation and wave height calculation steps: Calculate the directional spectrum of short-crest waves based on the propagation direction of wind and wave harmonics. Then, in ground coordinates, construct a first expression for the energy of long-crest waves based on wave amplitude and seawater density. Establish an angular frequency range based on the wind and wave angular frequency and the bandwidth set according to the wind and wave angular frequency, and obtain a second expression for the energy of long-crest waves within the angular frequency range. From the second expression, derive a third expression for the energy spectrum of long-crest waves, and then calculate the energy spectrum of long-crest waves. Calculate the short-crest wave wind and wave spectrum based on the directional spectrum of short-crest waves and the energy spectrum of long-crest waves. Establish a fourth expression for the energy of short-crest waves based on the short-crest wave wind and wave spectrum. Calculate the first expression for the energy of short-crest waves using the fourth expression and the short-crest wave wind and wave model. First, a wave surface equation is established. Then, a first relationship between the encounter period and the encounter angular frequency is established, and the angle between the ship's speed direction and the main propagation direction of the wind and waves is taken as the ship's encounter angle. Based on the ship's encounter angle, the natural period of the wind and waves, the natural wave speed of the wind and waves, and the ship's speed, a second relationship about the encounter period is established. Based on the ship's encounter angle, the wind and waves angular frequency, the natural wave speed of the wind and waves, and the ship's speed, a third relationship about the encounter angular frequency is established. Based on the first, second, and third relationships, and using coordinate and frequency transformation methods, the first wave surface equation located in the ground coordinate system is transformed into the ship's stable coordinate system to obtain a second wave surface equation applicable to the ship's surrounding environment. The wave height encountered by the ship during navigation is calculated based on the second wave surface equation.

[0058] Specifically, the direction spectrum of short-crest waves is first calculated based on the propagation direction of wind and wave harmonics, using the following formula:

[0059]

[0060] The 12th ITTC proposed temporarily setting n in M(μ) to 1, then:

[0061]

[0062] Then, based on fluid mechanics, long-crest waves possess energy. Therefore, in terrestrial coordinates, a first expression for the energy E of long-crest waves is constructed based on wave amplitude and seawater density, expressed as follows:

[0063]

[0064] Where i is the harmonic order, ζ ai Let ρ be the amplitude of the i-th harmonic, ρ be the density of seawater, and g be the acceleration due to gravity.

[0065] Based on the wave angular frequency ω and the bandwidth dω set based on the wave angular frequency, an angular frequency interval (ω, ω+dω) is established, and then a second expression for the energy of long-peak waves within the angular frequency interval is obtained, which is expressed as follows:

[0066]

[0067] The third expression for the long-peak wave energy spectrum is derived from the second expression, i.e., equation (8), which defines the long-peak wave energy spectrum S. ζ (ω) is shown in the following formula:

[0068]

[0069] The long-peak wave energy spectrum S can be calculated using Equation 9. ζ (ω).

[0070] Preferably, when the bandwidth in the third expression approaches zero, i.e. when dω→0, the integral expression for the long-peak wave energy is calculated based on the first and third expressions, as follows:

[0071]

[0072] The wave harmonic amplitude ζ can be obtained from the integral expression of the energy of long-peak waves. ai With spectral density function S ζ (ω) is related:

[0073]

[0074] The short-peak wave spectrum is based on the long-peak wave energy spectrum S. ζ Based on (ω), the directional spectrum M(μ) of short-crest waves is added. Therefore, the short-crest wave spectrum is calculated from the directional spectrum of short-crest waves and the energy spectrum of long-crest waves, and is expressed as follows:

[0075] S ζ (ω,μ)=S ζ (ω)M(μ) (10)

[0076] A fourth expression for the energy of short-crest wave waves is established based on the short-crest wave spectrum, as follows:

[0077]

[0078] Discretizing Equation 11 above and substituting it into the short crest wave model yields the first wave surface equation for the short crest wave, as follows:

[0079]

[0080] In summary, the state of the ocean wave at a certain moment can be obtained (the state includes wave height, energy distribution, waveform, and phase distribution).

[0081] When a ship navigates on the sea, the frequency of the waves it encounters differs from the frequency of the waves at a fixed point on the ocean surface due to its speed. When a ship is sailing against the waves, the frequency of the waves it encounters is higher than the frequency of the waves at a fixed point; conversely, when a ship is sailing with the waves, the frequency of the waves it encounters is lower than the frequency of the waves at a fixed point. Therefore, when studying the problem of ships navigating in wind and waves, we first define the period of the waves encountered by the ship as the encounter period T. e The corresponding angular frequency is called the encounter angular frequency ω. e It is related to the encounter period, and the first relationship between the encounter period and the encounter angular frequency is established, namely In addition, such as Figure 5 As shown, the encounter period T of the ships e and the encounter angular frequency ω e Related to the natural period T of the ocean waves, the angular frequency ω of the wind waves (also known as the natural angular frequency ω), the ship's speed V, and the ship's encounter angle μ e The relationship between the ship's speed V and the angle between the direction of wind and wave propagation, and the natural wave speed C, can be expressed as follows:

[0082]

[0083] Based on the above equations (13) and (14) and the encounter period T e With encounter angular frequency ω e The geometric relationship is determined, and the first wave surface equation, i.e., equation (12), located in the ground coordinate system is transformed into the ship's stable coordinate system through coordinate and frequency transformation methods (i.e., coordinate transformation based on the rotation matrix and transformation from wave frequency to encounter frequency), to obtain the second wave surface equation applicable to the short crest wave environment around the ship, which is expressed as follows:

[0084]

[0085] According to the second wave surface equation of short-crest waves, i.e., according to equation (15), the wave height ζ encountered by the ship during navigation can be calculated. e This indicates the shape of the sea waves encountered by a ship during navigation, and can more accurately reflect the actual sea wave conditions. In particular, it can accurately predict the wave height under complex sea conditions, reduce the risk of ships encountering extreme sea conditions, and thus protect the safety of ships and their crew.

[0086] Steps for obtaining the multi-wave superposition wave pressure model: In the ship's stable coordinate system, calculate the sea surface depth of a certain point underwater from the free surface based on the liquid surface depth under still water conditions and the wave height encountered by the ship during navigation. Construct a fifth expression for the pressure at a certain point underwater based on the sea surface depth and atmospheric pressure. Calculate a sixth expression for the pressure at a certain point underwater under short-crest wave conditions based on the fifth expression and the short-crest wave model. Obtain the wave pressure model caused by the waves based on the sixth expression, and correct the wave pressure model using the Smith correction term method to obtain the corrected wave pressure model. Finally, express the corrected wave pressure model as the superposition of multiple cosine waves using the harmonic superposition analysis method to obtain the multi-wave superposition wave pressure model.

[0087] Specifically, this step can also be understood as a study of the distribution of seawater pressure field beneath the sea surface. During the study, it is generally believed that the disturbance force and torque of ocean waves on the ship's hull are caused by fluctuations in the pressure field distribution beneath the liquid surface. Therefore, before analyzing the wind and wave forces and torques acting on the ship, the distribution of seawater pressure field beneath the sea surface is first studied. From the basic water pressure formula, the fifth expression, that is, the pressure P at a certain point underwater, can be expressed as:

[0088] P = P0 + ρgh (16)

[0089] Where P0 is atmospheric pressure; ρ is seawater density; g is gravitational acceleration; and h is the depth of a point underwater (also known as the research point) from the free surface of the liquid. Under wave conditions, the sea surface depth h can be expressed as the liquid surface depth z under still water conditions and the wave height ζ encountered by the ship during navigation. e The sum is expressed as follows:

[0090] h=z+ζ e (17)

[0091] Based on the fifth expression and the short crest wave model, the sixth expression for the pressure at a certain point underwater under short crest wave conditions is calculated. That is, by substituting equation (4) into equation (16), the sixth expression for the pressure at a certain point underwater under long crest wave conditions is obtained, as shown in the following equation:

[0092] P = P0 + ρgz + ρgζ a cos(kξ-ωt) (18)

[0093] Based on the sixth expression, the wave pressure model caused by ocean waves is defined as ΔP, then:

[0094] ΔP=ρgζ a cos(kξ-ωt) (19)

[0095] According to the Smith effect, the amplitude of wavefront ripple is affected by depth. Therefore, the Smith correction term is used to correct the wave pressure model, resulting in the corrected wave pressure model, as shown in the following equation:

[0096]

[0097]

[0098] ΔP=e -kz ρgζ a cos(kξ-ωt) (22)

[0099] Expanding within the ship's stable coordinate system, we have:

[0100] ΔP=e -kz ρgζ a cos(kx s cosμ e +ky s sinμ e -ω e t) (23)

[0101] The modified wave pressure model is represented as a superposition of multiple cosine waves by the harmonic superposition analysis method, resulting in a multi-wave superposition wave pressure model. That is, equation (23) is expressed as a superposition of cosine waves, as shown in the following equation:

[0102]

[0103] The calculation steps for interference force and interference moment are as follows: First, the wave pressure experienced by the ship is calculated based on the multi-wave superposition wave pressure model. Then, the wave pressure experienced by the ship is integrated to obtain the heave interference force. Next, the heave interference force is integrated along the direction of the ship's pitch axis to obtain the pitch interference moment experienced by the ship in the pitch direction. Then, the heave interference force is integrated along the bottom, left, and right directions of the ship's roll axis to obtain the bottom, left, and right side components of the roll interference moment experienced by the ship in the roll direction. Finally, the roll interference moment is calculated based on the bottom, left, and right side components of the roll interference moment to complete the analysis of the ship's wind and wave load and dynamic response.

[0104] Specifically, this step can also be understood as the analysis of the wind and wave forces and moments acting on the ship. In the process of analyzing the wind and wave forces and moments acting on the ship, the widely used Froude-Krylov assumption is used as a simplifying condition, the main contents of which are:

[0105] 1) The force and torque of wind and waves are caused solely by fluid pressure;

[0106] 2) The presence of the ship's hull does not affect the distribution of wind and waves;

[0107] 3) The disturbance force and torque of the waves on the ship's hull are caused by the fluctuation of the pressure field distribution under the liquid surface.

[0108] Based on the Froude-Krylov hypothesis, the wave pressure ΔP caused by ocean waves, as shown in equation (24), can be integrated across the underwater surfaces of the hull to obtain the wave force and moment. In engineering, since the shape of ships is often complex, when a detailed hull line drawing is unavailable, the hull can be approximated as having a length L, a beam B, and a mean draft, respectively. Even when calculating wave force and wave moment using a cuboid, relatively accurate results can still be obtained.

[0109] Force analysis of the bottom surface of the hull as follows Figure 6 As shown, the heave disturbance force Z of the ship... w It can be obtained by integrating the wave pressure experienced by the ship at the bottom of the ship, as shown in the following formula:

[0110]

[0111] The heave disturbance force is then integrated along the direction of the ship's pitch axis to obtain the pitch disturbance torque M experienced by the ship in the pitch direction. w This can also be understood as being achieved through the heave disturbance force Z. w The pitch disturbance moment M of the ship is obtained by taking the moment about the pitch axis. w As shown in the following formula:

[0112]

[0113] Then, the heave disturbance force is integrated along the bottom, left, and right directions of the ship's roll axis to obtain the bottom, left, and right components of the roll disturbance moment experienced by the ship in the roll direction. The bottom component K of the ship's roll disturbance moment is then calculated. w1 The equation is obtained by taking the moment about the ship's roll axis from the heave disturbance force, as shown below:

[0114]

[0115] Force analysis of the side of the hull as follows Figure 7 As shown, the right-hand side component of the ship's roll disturbance moment can be obtained by taking the moment of the roll disturbance force about the ship's roll axis, as shown in the following formula:

[0116]

[0117] Left side component K w3 Similarly, in summary, based on the bottom component K of the roll disturbance torque... w1 Left side component K w3and the right side component K w2 Calculate the roll disturbance moment, K. w for:

[0118] K w =K w1 +K w2 +K w3 (29)

[0119] This invention also relates to a system for analyzing ship wind and wave loads and dynamic response under short crest wave sea states. This system corresponds to the aforementioned method for analyzing ship wind and wave loads and dynamic response under short crest wave sea states, and can be understood as a system that implements the aforementioned method. The system includes, in sequence, a parameter acquisition and coordinate system establishment module, a short crest wave model construction module, a wave surface equation and wave height calculation module, a multi-wave superposition wave pressure model acquisition module, and a disturbance force and disturbance torque calculation module. Specifically,

[0120] The parameter acquisition and coordinate system establishment module acquires wind and wave characteristic parameters and ship motion state parameters under different sea states, and establishes a ground coordinate system with any point on the sea surface as the origin, the ship's motion direction as the abscissa, the ship's starboard side parallel to the sea surface as the ordinate, and the Earth's center as the vertical coordinate; and establishes a ship stability coordinate system with the ship's center of mass as the origin, the ship's motion direction as the abscissa, the ship's starboard side parallel to the sea surface as the ordinate, and the Earth's center as the vertical coordinate; the wind and wave characteristic parameters include wave amplitude, wave number, main propagation direction of wind and waves, propagation direction of wind and wave harmonics, wind and wave angular frequency, time of wind and wave morphology transformation, natural period of wind and waves, and natural wave speed; the ship's motion state parameters include ship speed, encounter period, and encounter angular frequency.

[0121] The short crest wave model construction module establishes a plane wave equation about the wave height in the ground coordinate system based on wave amplitude, wave number, main propagation direction of wind and waves, propagation direction of wind and wave harmonics, and time of wind and wave morphology transformation, and then recursively obtains the short crest wave model based on the plane wave equation.

[0122] The wave surface equation and wave height calculation module calculates the directional spectrum of short-crest waves based on the propagation direction of wind and wave harmonics. In ground coordinates, it constructs a first expression for the energy of long-crest waves based on wave amplitude and seawater density. It establishes an angular frequency range based on the wind and wave angular frequency and a bandwidth set accordingly, thus obtaining a second expression for the energy of long-crest waves within this range. From the second expression, a third expression for the energy spectrum of long-crest waves is recursively derived, and the energy spectrum of long-crest waves is calculated. Based on the directional spectrum of short-crest waves and the energy spectrum of long-crest waves, the wind and wave spectrum of short-crest waves is calculated. A fourth expression for the energy of short-crest waves is established based on this spectrum. The wind and wave spectrum of short-crest waves is then calculated using the fourth expression and the short-crest wave model. The first wave surface equation is then established; a first relationship between the encounter period and the encounter angular frequency is established, and the angle between the ship's speed direction and the main propagation direction of the wind and waves is taken as the ship's encounter angle. Based on the ship's encounter angle, the natural period of the wind and waves, the natural wave speed of the wind and waves, and the ship's speed, a second relationship about the encounter period is established, and based on the ship's encounter angle, the wind and waves angular frequency, the natural wave speed of the wind and waves, and the ship's speed, a third relationship about the encounter angular frequency is established. Based on the first, second, and third relationships, and using coordinate and frequency transformation methods, the first wave surface equation located in the ground coordinate system is transformed into the ship's stable coordinate system to obtain the second wave surface equation applicable to the ship's surrounding environment. The wave height encountered by the ship during navigation is then calculated based on the second wave surface equation.

[0123] The multi-wave superposition wave pressure model acquisition module calculates the sea surface depth of a point underwater from the free surface based on the liquid surface depth under still water conditions and the wave height encountered by the ship during navigation in the ship's stable coordinate system. It then constructs a fifth expression for the pressure at that point underwater based on the sea surface depth and atmospheric pressure. Next, it calculates a sixth expression for the pressure at that point underwater under short-crest wave conditions based on the fifth expression and the short-crest wave model. Finally, it obtains a wave pressure model caused by waves based on the sixth expression and corrects it using the Smith correction term method to obtain the corrected wave pressure model. Finally, it uses harmonic superposition analysis to represent the corrected wave pressure model as a superposition of multiple cosine waves, thus obtaining a multi-wave superposition wave pressure model.

[0124] The interference force and interference moment calculation module calculates the wave pressure on the ship based on the multi-wave superposition wave pressure model, and performs integration calculation on the wave pressure on the ship's bottom based on the Froude-Krylov assumption and the prismatic ship assumption to obtain the heave interference force of the ship; then, it integrates the heave interference force along the direction of the ship's pitch axis to obtain the pitch interference moment of the ship in the pitch direction; it integrates the heave interference force along the bottom, left, and right directions of the ship's roll axis to obtain the bottom, left, and right side components of the roll interference moment of the ship in the roll direction; and finally, it calculates the roll interference moment based on the bottom, left, and right side components of the roll interference moment to complete the analysis of the ship's wind and wave load and dynamic response.

[0125] Preferably, in the wave surface equation and wave height calculation module, when the bandwidth in the third expression approaches zero, the integral expression of the long-peak wave energy is calculated based on the first and third expressions, and the relationship between the wave harmonic amplitude and the spectral density function is calculated based on the integral expression.

[0126] Preferably, in the parameter acquisition and coordinate system establishment module, the wind and wave characteristic parameters also include wavelength, and the wave number is calculated based on the wavelength.

[0127] Preferably, the coordinate and frequency transformation method includes coordinate transformation based on a rotation matrix and transformation from wave frequency to encounter frequency.

[0128] This invention provides an objective and scientific method and system for analyzing ship wind and wave loads and dynamic responses under short-peak wave sea states. Based on the characteristic parameters of wind and waves and the ship's speed, a long-peak wave model is established. The wave surface equation is obtained using specific calculation and coordinate transformation methods, and a multi-wave superposition wave pressure model (wind and wave load) is obtained through specific correction methods. Then, the disturbance force and disturbance torque (dynamic response) are calculated. This can more accurately predict the dynamic response of ships in wind and waves and more accurately assess the take-off and landing safety of shipborne helicopters under high sea state conditions, effectively improving the calculation accuracy.

[0129] It should be noted that the specific embodiments described above 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 the present invention has been described in detail with reference to the accompanying drawings and embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention. In short, all technical solutions and improvements that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the present invention patent.

Claims

1. A method for analyzing ship wind and wave loads and dynamic response under short-peak wave sea states, characterized in that, Includes the following steps: Steps for parameter acquisition and coordinate system establishment: Acquire wind and wave characteristic parameters and ship motion state parameters under different sea states, and establish a ground coordinate system with any point on the sea surface as the origin, the ship's motion direction as the abscissa, the ship's starboard side parallel to the sea surface as the ordinate, and the geocenter as the vertical coordinate; establish a ship stability coordinate system with the ship's center of mass as the origin, the ship's motion direction as the abscissa, the ship's starboard side parallel to the sea surface as the ordinate, and the geocenter as the vertical coordinate; the wind and wave characteristic parameters include wave amplitude, wave number, main propagation direction of wind and waves, propagation direction of wind and wave harmonics, wind and wave angular frequency, time of wind and wave morphology transformation, natural period of wind and waves, and natural wave speed; the ship's motion state parameters include ship speed, encounter period, and encounter angular frequency. Steps for constructing a short crest wave model: In the ground coordinate system, establish a plane wave equation about the wave height based on wave amplitude, wave number, main propagation direction of wind and waves, propagation direction of wind and wave harmonics, and time of wind and wave morphology transformation. Then, recursively derive the short crest wave model based on the plane wave equation. Wave surface equation and wave height calculation steps: Calculate the directional spectrum of short-crest waves based on the propagation direction of wind and wave harmonics. Then, in ground coordinates, construct a first expression for the energy of long-crest waves based on wave amplitude and seawater density. Establish an angular frequency range based on the wind and wave angular frequency and the bandwidth set according to the wind and wave angular frequency, and obtain a second expression for the energy of long-crest waves within the angular frequency range. From the second expression, derive a third expression for the energy spectrum of long-crest waves, and then calculate the energy spectrum of long-crest waves. Calculate the short-crest wave wind and wave spectrum based on the directional spectrum of short-crest waves and the energy spectrum of long-crest waves. Establish a fourth expression for the energy of short-crest waves based on the short-crest wave wind and wave spectrum. Calculate the first expression for the energy of short-crest waves using the fourth expression and the short-crest wave wind and wave model. First, a wave surface equation is established. Then, a first relationship between the encounter period and the encounter angular frequency is established, and the angle between the ship's speed direction and the main propagation direction of the wind and waves is taken as the ship's encounter angle. Based on the ship's encounter angle, the natural period of the wind and waves, the natural wave speed of the wind and waves, and the ship's speed, a second relationship about the encounter period is established. Based on the ship's encounter angle, the wind and waves angular frequency, the natural wave speed of the wind and waves, and the ship's speed, a third relationship about the encounter angular frequency is established. Based on the first, second, and third relationships, and using coordinate and frequency transformation methods, the first wave surface equation located in the ground coordinate system is transformed into the ship's stable coordinate system to obtain a second wave surface equation applicable to the ship's surrounding environment. The wave height encountered by the ship during navigation is calculated based on the second wave surface equation. Steps for obtaining the multi-wave superposition wave pressure model: In the ship's stable coordinate system, calculate the sea surface depth of a certain point underwater from the free surface based on the liquid surface depth under still water conditions and the wave height encountered by the ship during navigation, and construct the fifth expression for the pressure of a certain point underwater based on the sea surface depth and atmospheric pressure; calculate the sixth expression for the pressure of a certain point underwater under short-crest wave conditions based on the fifth expression and the short-crest wave model. Based on the sixth expression, the wave pressure model caused by ocean waves is obtained, and the wave pressure model is corrected by the Smith correction term method to obtain the corrected wave pressure model; and the corrected wave pressure model is expressed as the superposition of multiple cosine waves by the harmonic superposition analysis method to obtain the multi-wave superposition wave pressure model. The calculation steps for interference force and interference moment are as follows: The wave pressure on the ship is calculated based on the multi-wave superposition wave pressure model. Then, based on the Froude-Krylov assumption and the prismatic ship assumption, the wave pressure on the ship is integrated at the bottom of the ship to obtain the heave interference force. Next, the heave interference force is integrated along the direction of the ship's pitch axis to obtain the pitch interference moment on the ship in the pitch direction. Finally, the heave interference force is integrated along the bottom, left, and right directions of the ship's roll axis to obtain the bottom, left, and right components of the roll interference moment on the ship in the roll direction. The roll disturbance moment is calculated based on the bottom, left, and right side components of the roll disturbance moment to complete the analysis of the ship's wind and wave load and dynamic response.

2. The method for analyzing ship wind and wave loads and dynamic response under short-peak wave sea states according to claim 1, characterized in that, In the wave surface equation and wave height calculation steps, when the bandwidth in the third expression approaches zero, the integral expression of the long-peak wave energy is calculated based on the first and third expressions, and the relationship between the wave harmonic amplitude and the spectral density function is calculated based on the integral expression.

3. The method for analyzing ship wind and wave loads and dynamic response under short-peak wave sea states according to claim 1, characterized in that, In the parameter acquisition and coordinate system establishment steps, the wind and wave characteristic parameters also include wavelength, and the wave number is calculated based on the wavelength.

4. The method for analyzing ship wind and wave loads and dynamic response under short-peak wave sea states according to claim 1, characterized in that, The coordinate and frequency transformation methods include coordinate transformation based on rotation matrices and transformation from wave frequency to encounter frequency.

5. A system for analyzing ship wind and wave loads and dynamic response under short-peak wave sea states, characterized in that, The module includes, in sequence, a parameter acquisition and coordinate system establishment module, a short-peak wave model construction module, a wave surface equation and wave height calculation module, a multi-wave superposition wave pressure model acquisition module, and a disturbance force and disturbance torque calculation module. The parameter acquisition and coordinate system establishment module acquires wind and wave characteristic parameters and ship motion state parameters under different sea states, and establishes a ground coordinate system with any point on the sea surface as the origin, the ship's motion direction as the abscissa, the ship's starboard side parallel to the sea surface as the ordinate, and the Earth's center as the vertical coordinate; and establishes a ship stability coordinate system with the ship's center of mass as the origin, the ship's motion direction as the abscissa, the ship's starboard side parallel to the sea surface as the ordinate, and the Earth's center as the vertical coordinate; the wind and wave characteristic parameters include wave amplitude, wave number, main propagation direction of wind and waves, propagation direction of wind and wave harmonics, wind and wave angular frequency, time of wind and wave morphology transformation, natural period of wind and waves, and natural wave speed; the ship's motion state parameters include ship speed, encounter period, and encounter angular frequency. The short crest wave model construction module establishes a plane wave equation about the wave height in the ground coordinate system based on wave amplitude, wave number, main propagation direction of wind and waves, propagation direction of wind and wave harmonics, and time of wind and wave morphology transformation, and then recursively obtains the short crest wave model based on the plane wave equation. The wave surface equation and wave height calculation module calculates the directional spectrum of short-crest waves based on the propagation direction of wind and wave harmonics. In ground coordinates, it constructs a first expression for the energy of long-crest waves based on wave amplitude and seawater density. It establishes an angular frequency range based on the wind and wave angular frequency and a bandwidth set accordingly, thus obtaining a second expression for the energy of long-crest waves within this range. From the second expression, a third expression for the energy spectrum of long-crest waves is recursively derived, and the energy spectrum of long-crest waves is calculated. Based on the directional spectrum of short-crest waves and the energy spectrum of long-crest waves, the wind and wave spectrum of short-crest waves is calculated. A fourth expression for the energy of short-crest waves is established based on this spectrum. The wind and wave spectrum of short-crest waves is then calculated using the fourth expression and the short-crest wave model. The first wave surface equation is then established; a first relationship between the encounter period and the encounter angular frequency is established, and the angle between the ship's speed direction and the main propagation direction of the wind and waves is taken as the ship's encounter angle. Based on the ship's encounter angle, the natural period of the wind and waves, the natural wave speed of the wind and waves, and the ship's speed, a second relationship about the encounter period is established, and based on the ship's encounter angle, the wind and waves angular frequency, the natural wave speed of the wind and waves, and the ship's speed, a third relationship about the encounter angular frequency is established. Based on the first, second, and third relationships, and using coordinate and frequency transformation methods, the first wave surface equation located in the ground coordinate system is transformed into the ship's stable coordinate system to obtain the second wave surface equation applicable to the ship's surrounding environment. The wave height encountered by the ship during navigation is then calculated based on the second wave surface equation. The multi-wave superposition wave pressure model acquisition module calculates the sea surface depth of a certain point underwater from the free liquid surface based on the liquid surface depth under still water conditions and the wave height encountered by the ship during navigation in the stable coordinate system of the ship. It then constructs a fifth expression for the pressure of a certain point underwater based on the sea surface depth and atmospheric pressure. Based on the fifth expression and the short crest wave model, it calculates a sixth expression for the pressure of a certain point underwater under short crest wave conditions. Based on the sixth expression, the wave pressure model caused by ocean waves is obtained, and the wave pressure model is corrected by the Smith correction term method to obtain the corrected wave pressure model; and the corrected wave pressure model is expressed as the superposition of multiple cosine waves by the harmonic superposition analysis method to obtain the multi-wave superposition wave pressure model. The interference force and interference moment calculation module calculates the wave pressure on the ship based on the multi-wave superposition wave pressure model, and performs integral calculation on the wave pressure on the ship at the bottom of the ship based on the Froude-Krylov assumption and the prismatic ship assumption to obtain the heave interference force of the ship; then, it performs integral calculation on the heave interference force along the direction of the ship's pitch axis to obtain the pitch interference moment of the ship in the pitch direction; and then it performs integral calculation on the bottom direction, left direction and right direction of the ship's roll axis to obtain the bottom component, left side component and right side component of the roll interference moment of the ship in the roll direction. The roll disturbance moment is calculated based on the bottom, left, and right side components of the roll disturbance moment to complete the analysis of the ship's wind and wave load and dynamic response.

6. The ship wind and wave load and dynamic response analysis system under short-peak wave sea state as described in claim 5, characterized in that, In the wave surface equation and wave height calculation module, when the bandwidth in the third expression approaches zero, the integral expression of the long-peak wave energy is calculated based on the first and third expressions, and the relationship between the wave harmonic amplitude and the spectral density function is calculated based on the integral expression.

7. The ship wind and wave load and dynamic response analysis system under short-peak wave sea state according to claim 5, characterized in that, In the parameter acquisition and coordinate system establishment module, the wind and wave characteristic parameters also include wavelength, and the wave number is calculated based on the wavelength.

8. The ship wind and wave load and dynamic response analysis system under short-peak wave sea state according to claim 5, characterized in that, The coordinate and frequency transformation methods include coordinate transformation based on rotation matrices and transformation from wave frequency to encounter frequency.

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