Ship wind wave load and dynamic response analysis method and system under short peak wave sea condition

Abstract

The invention provides a ship storm load and dynamic response analysis method and system under a short-peak wave sea condition, and the method comprises the steps: building a long-peak wave model based on storm characteristic parameters under different sea conditions and motion state parameters of a ship, and carrying out the calculation under ground coordinates to obtain a first wave surface equation; a first wave surface equation located in a ground coordinate system is converted into a ship body stable coordinate system through a coordinate and frequency conversion method, a second wave surface equation suitable for the surrounding environment of the ship is obtained, then a fluctuation pressure model caused by sea waves is established, the fluctuation pressure model is corrected through an exponential decay method, and the ship body stable coordinate system is obtained. A multi-wave superposition fluctuation pressure model is obtained through a coordinate and frequency conversion method and a harmonic superposition analysis method; finally, the disturbance force and the disturbance torque are calculated through a specific calculation method, the dynamic response of a ship in stormy waves can be predicted more accurately, the take-off and landing safety of a ship-borne helicopter under the high sea condition can be evaluated more accurately, and the calculation precision is effectively improved.

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 wind and wave loads and dynamic responses of ships under short-peak wave sea conditions. Background Art

[0002] In modern naval warfare, air power has become an indispensable and important support for naval ships. With the continuous development and growth of my country's navy in recent years, its demand for ship-borne aviation power has also gradually increased. At the same time, the maturity of ship-borne helicopter technology and the continuous development of new vertical take-off and landing aircraft have made non-through-deck ships such as frigates and destroyers play an increasingly important role in the field of ship-borne aviation force delivery.

[0003] However, the ocean environment dominated by wind and waves and ocean weather changes, and the ship environment dominated by ship wake and deck disturbances, will directly affect the flight performance of ship-borne helicopters and other aircraft, and even directly endanger flight safety. Especially in high sea conditions, due to the violent shaking of the ship and the harsh flow field environment, ship-borne helicopters and other aircraft often find it difficult to perform take-off and landing missions normally, which poses a severe challenge to the ship-borne aviation combat capability.

[0004] At present, existing technologies have certain limitations when dealing with these problems. For example, traditional wind and wave models and ship motion models do not fully consider the dynamic characteristics of wind and waves, such as amplitude, wave number, propagation direction, etc., resulting in an inaccurate description of wind and wave behavior, which makes it impossible to accurately predict the dynamic response of ships under high sea conditions, making it difficult to accurately evaluate the safety of take-off and landing of ship-borne helicopters. In addition, the existing wave pressure calculation method ignores the nonlinear effect and the interaction between wind and waves, resulting in inaccurate calculation of interference forces and interference torques, affecting the safety and reliability of ship design. Moreover, the existing interference force and interference torque calculation methods fail to fully consider the impact of wind and waves on ships, thereby affecting the evaluation of the safety of take-off and landing of ship-borne helicopters.

[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 ship-borne helicopters under complex sea conditions, so as to improve the safety and efficiency of ship-borne aviation operations. Summary of the invention

[0006] The present invention aims at the problems that the description of wind and wave behavior is not accurate enough, the calculation results are not accurate enough, and the influence of wind and waves on ships is not fully considered in the analysis process of wind and wave loads and dynamic responses of ships under complex sea conditions. A method for analyzing wind and wave loads and dynamic responses of ships under short-peak wave sea conditions is provided. A short-peak wave wind and wave model is established based on the characteristic parameters of wind and waves and the motion state parameters of the ship, and a wave surface equation is obtained by using a specific calculation method and coordinate transformation method, and a multi-wave superposition fluctuation pressure model (wind and wave load) is obtained by a specific correction method, and then the interference force and interference torque (dynamic response) are calculated, which can more accurately predict the dynamic response of the ship in wind and waves, and can more accurately evaluate the take-off and landing safety of ship-borne helicopters under high sea conditions, effectively improving the calculation accuracy. The present invention also relates to a ship wind and wave load and dynamic response analysis system under short-peak wave sea conditions.

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

[0008] A method for analyzing wind and wave loads and dynamic response of a ship under short-peak wave sea conditions, characterized in that it comprises the following steps:

[0009] Parameter acquisition and coordinate system establishment steps: obtain wind and wave characteristic parameters and ship motion state parameters under different sea conditions, and establish a ground coordinate system with any point on the sea level as the origin, the ship motion direction as the horizontal coordinate, the direction of the starboard side of the ship parallel to the sea level as the vertical coordinate, and the center of the earth as the vertical coordinate; establish a hull stable coordinate system with the ship's center of mass as the origin, the ship motion direction as the horizontal coordinate, the direction of the starboard side of the ship parallel to the sea level as the vertical coordinate, and the center of the earth as the vertical coordinate; the wind and wave characteristic parameters include 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, wind and wave natural period and wind and wave natural wave speed; the ship's motion state parameters include ship speed, encounter period and encounter angular frequency;

[0010] The steps of constructing the short-peaked wave wind and wave model are as follows: in the ground coordinate system, a plane wave equation about the wave height is established based on the wave amplitude, wave number, main propagation direction of wind and wave, propagation direction of wind and wave harmonics, and the time of wind and wave shape transformation, and the short-peaked wave wind and wave model is obtained by recursion based on the plane wave equation;

[0011] The wave surface equation and wave height calculation steps are as follows: the directional spectrum of short-peaked waves is calculated according to the propagation direction of wind and wave harmonics, and a first expression about the energy of long-peaked waves is constructed according to the wave amplitude and seawater density under ground coordinates, an angular frequency interval is established according to the wind and wave angular frequency and the bandwidth set based on the wind and wave angular frequency, and then a second expression about the energy of long-peaked waves within the angular frequency interval is obtained, and a third expression about the energy spectrum of long-peaked waves is recursively obtained from the second expression, and then the long-peaked wave energy spectrum is calculated; a short-peaked wave wind and wave spectrum is calculated according to the directional spectrum of short-peaked waves and the energy spectrum of long-peaked waves, a fourth expression about the energy of short-peaked waves is established based on the short-peaked wave wind and wave spectrum, and the fourth expression of the energy of short-peaked waves is calculated by the fourth expression and the short-peaked wave wind and wave model. A wave surface equation is established; then a first relational expression between the encounter period and the encounter angular frequency is established, and the angle between the ship speed direction and the main propagation direction of the wind and waves is taken as the ship encounter angle, and a second relational expression about the encounter period is established based on the ship encounter angle, the natural period of the wind and waves, the natural wave speed of the wind and waves, and the ship speed, and a third relational expression about the encounter angular frequency is established based on the ship encounter angle, the angular frequency of the wind and waves, the natural wave speed of the wind and waves, and the ship speed; based on the first relational expression, the second relational expression and the third relational expression, and using the coordinate and frequency transformation method, the first wave surface equation located in the ground coordinate system is converted into the hull stable coordinate system, and a second wave surface equation applicable to the surrounding environment of the ship is obtained, and the wave height encountered by the ship during navigation is calculated according to the second wave surface equation;

[0012] Steps for obtaining the multi-wave superposition fluctuation pressure model: in the hull stable coordinate system, the sea surface depth of a certain underwater point from the free liquid surface is calculated according to the liquid surface depth under still water conditions and the wave height encountered by the ship during navigation, and a fifth expression for the pressure at a certain underwater point is constructed according to the sea surface depth and the atmospheric pressure; a sixth expression for the pressure at a certain underwater point under short-peak wave and sea wave conditions is calculated according to the fifth expression and the short-peak wave wind and wave model; a fluctuation pressure model caused by sea waves is obtained according to the sixth expression, and the fluctuation pressure model is corrected by the Smith correction term method to obtain a corrected fluctuation pressure model; and the corrected fluctuation pressure model is expressed as a superposition of multiple cosine waves by the harmonic superposition analysis method to obtain a multi-wave superposition fluctuation pressure model;

[0013] Calculation steps of disturbance force and disturbance moment: calculate the wave pressure on the ship according to the multi-wave superposition wave pressure model, and based on the Froud-Krylov hypothesis and the square ship hypothesis, integrate the wave pressure on the ship at the bottom of the ship to obtain the heave disturbance force of the ship; then integrate the heave disturbance force in the direction of the hull's pitch axis to obtain the pitch disturbance moment on the ship in the pitch direction; integrate the heave disturbance force in the bottom direction, left direction and right direction of the hull's roll axis respectively to obtain the bottom component, left side component and right side component of the roll disturbance moment on the ship in the roll direction; calculate the roll disturbance moment according to the bottom component, left side component and right side component of the roll disturbance moment to complete the analysis of ship wind and wave load and dynamic response.

[0014] Preferably, in the wave surface equation and wave height calculation step, when the bandwidth in the third expression tends to zero, the integral expression of the long-peak wave energy is calculated according to the first expression and the third expression, and the relationship between the wave harmonic amplitude and the spectral density function is calculated according to the integral expression.

[0015] Preferably, 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.

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

[0017] A ship wind and wave load and dynamic response analysis system under short-peak wave sea conditions, characterized by comprising a parameter acquisition and coordinate system establishment module, a short-peak wave wind and wave model construction module, a wave surface equation and sea wave height calculation module, a multi-wave superposition wave pressure model acquisition module, and an interference force and interference torque calculation module connected in sequence,

[0018] The parameter acquisition and coordinate system establishment module acquires wind and wave characteristic parameters and ship motion state parameters under different sea conditions, and establishes a ground coordinate system with any point on the sea level as the origin, the ship motion direction as the horizontal coordinate, the direction of the starboard side of the ship parallel to the sea level as the vertical coordinate, and the center of the earth as the vertical coordinate; establishes a hull stable coordinate system with the ship's center of mass as the origin, the ship motion direction as the horizontal coordinate, the direction of the starboard side of the ship parallel to the sea level as the vertical coordinate, and the center of the earth as the vertical coordinate; the wind and wave characteristic parameters include 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, wind and wave natural period, and wind and wave natural wave speed; the ship's motion state parameters include ship speed, encounter period, and encounter angular frequency;

[0019] The short-peaked wave wind and wave model construction module establishes a plane wave equation about the wave height in the ground coordinate system based on the wave amplitude, wave number, main propagation direction of wind and waves, propagation direction of wind and wave harmonics, and time of wind and wave shape transformation, and recursively obtains the short-peaked wave wind and wave model according to the plane wave equation;

[0020] The wave surface equation and wave height calculation module calculates the directional spectrum of short-peaked waves according to the propagation direction of wind and wave harmonics, and constructs a first expression for the energy of long-peaked waves according to the wave amplitude and seawater density under ground coordinates, establishes an angular frequency interval according to the wind and wave angular frequency and the frequency band width set based on the wind and wave angular frequency, and then obtains a second expression for the energy of long-peaked waves within the angular frequency interval, and recursively obtains a third expression for the energy spectrum of long-peaked waves from the second expression, and then calculates the energy spectrum of long-peaked waves; calculates the short-peaked wave wind and wave spectrum according to the directional spectrum of short-peaked waves and the long-peaked wave energy spectrum, establishes a fourth expression for the energy of short-peaked waves based on the short-peaked wave wind and wave spectrum, and calculates the short-peaked wave wind and wave model by the fourth expression. The first wave surface equation; then establish a first relationship between the encounter period and the encounter angular frequency, and take the angle between the ship speed direction and the main propagation direction of the wind and waves as the ship encounter angle, and establish a second relationship about the encounter period based on the ship encounter angle, the natural period of wind and waves, the natural wave speed of wind and waves, and the ship speed, and establish a third relationship about the encounter angular frequency based on the ship encounter angle, the angular frequency of wind and waves, the natural wave speed of wind and waves, and the ship speed; based on the first relationship, the second relationship, and the third relationship, and using the coordinate and frequency transformation method, the first wave surface equation located in the ground coordinate system is converted into the hull stable coordinate system, and the second wave surface equation applicable to the surrounding environment of the ship is obtained, and the wave height encountered by the ship during navigation is calculated according to the second wave surface equation;

[0021] The multi-wave superposition fluctuation pressure model acquisition module calculates the sea surface depth of a certain underwater point from the free liquid surface according to the liquid surface depth under calm water conditions and the wave height encountered by the ship during navigation in a stable coordinate system of the hull, and constructs a fifth expression for the pressure of a certain underwater point according to the sea surface depth and the atmospheric pressure; calculates a sixth expression for the pressure of a certain underwater point under short-peak wave and sea wave conditions according to the fifth expression and the short-peak wave wind and wave model; obtains the fluctuation pressure model caused by the sea waves according to the sixth expression, and corrects the fluctuation pressure model by using the Smith correction term method to obtain the corrected fluctuation pressure model; and expresses the corrected fluctuation pressure model as the superposition of multiple cosine waves by using the harmonic superposition analysis method to obtain the multi-wave superposition fluctuation pressure model;

[0022] The disturbance force and disturbance torque calculation module calculates the wave pressure received by the ship according to the multi-wave superposition wave pressure model, and based on the Froud-Krylov hypothesis and the square ship hypothesis, integrates the wave pressure received by the ship at the bottom of the ship to obtain the heave disturbance force of the ship; then integrates the heave disturbance force in the direction of the hull pitch axis to obtain the pitch disturbance torque received by the ship in the pitch direction; integrates the heave disturbance force in the bottom direction, left direction and right direction of the hull roll axis respectively to obtain the bottom component, left side component and right side component of the roll disturbance torque received by the ship in the roll direction; calculates the roll disturbance torque according to the bottom component, left side component and right side component of the roll disturbance torque, so as to complete the ship wind and wave load and dynamic response analysis.

[0023] Preferably, in the wave surface equation and wave height calculation module, when the bandwidth in the third expression tends to zero, the integral expression of the long-peak wave energy is calculated according to the first expression and the third expression, and the relationship between the wave harmonic amplitude and the spectral density function is calculated according to 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 rotation matrix and transformation of wave frequency to encounter frequency.

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

[0027] The present invention provides a method for analyzing wind and wave loads and dynamic responses of ships under short-peak wave sea conditions. Based on the characteristic parameters of wind and waves under different sea conditions and the motion state parameters of the ship, a short-peak wave wind and wave model including multiple characteristic parameters such as amplitude, wave number, main propagation direction of wind and waves, propagation direction of wind and wave harmonics is established, so that the behavior of wind and waves and their influence on the ship can be described more accurately and quickly, thereby improving the accuracy of the model. Based on the established ground coordinate system and hull stable coordinate system, the wind and wave model is converted from the ground coordinate system to the hull coordinate system through the coordinate and frequency transformation method, so that the actual motion state of the ship in the waves can be more accurately reflected. Then, a second wave surface equation suitable for the surrounding environment of the ship is calculated by adopting a specific calculation method and constructed expressions and relations, and the wave height encountered by the ship during navigation is calculated according to the second wave surface equation, so that the actual wave conditions can be reflected more accurately, especially for accurate wave height prediction under complex sea conditions, thereby reducing the risk of the ship encountering extreme sea conditions. And protect the safety of the ship and its crew; then use the Smith correction term method to correct the fluctuating pressure model obtained by the established expressions to obtain the corrected fluctuating pressure model to improve the calculation accuracy, and can effectively and accurately evaluate the stress of the ship in the wind and waves; and obtain the multi-wave superposition fluctuating pressure model by the harmonic superposition analysis method. The multi-wave superposition fluctuating pressure model takes into account the pressure change at a certain point underwater, the interaction between wind and waves and the nonlinear effect, effectively improves the accuracy and reliability of the fluctuating pressure calculation, and makes the prediction of the dynamic response of the ship more accurate; finally, based on the calculated fluctuating pressure of the ship and using a specific calculation method to calculate the heave interference force and the pitch and roll interference moment, by fully considering the pressure distribution of the wind and waves on the surface of the ship, the force distribution of the ship in the wind and waves can be better understood, and the safety of the take-off and landing of the ship-borne helicopter under high sea conditions can be more accurately evaluated, which is of great significance to ensure the safe take-off and landing of the ship-borne helicopter under high sea conditions. The present invention can effectively improve the take-off and landing capability and safety of carrier-based aircraft under complex sea conditions, thereby enhancing the overall combat effectiveness of carrier-based aviation forces.

[0028] The present invention also relates to a system for analyzing ship wind and wave loads and dynamic responses under short-peak wave sea conditions. The system corresponds to the above-mentioned method for analyzing ship wind and wave loads and dynamic responses under short-peak wave sea conditions, and can be understood as a system for realizing the above-mentioned method for analyzing ship wind and wave loads and dynamic responses under short-peak wave sea conditions, including a parameter acquisition and coordinate system establishment module, a long-peak wave model construction module, a wave surface equation and wave height calculation module, a multi-wave superposition fluctuation pressure model acquisition module, and an interference force and interference torque calculation module, which are connected in sequence. The modules cooperate with each other to establish a short-peak wave wind and wave model based on the characteristic parameters of the wind and waves and the motion state parameters of the ship, and adopt a specific calculation method and coordinate conversion method to obtain the wave surface equation, and obtain the multi-wave superposition fluctuation pressure model (wind and wave load) through a specific correction method, and then calculate the interference force and interference torque (dynamic response), which can more accurately predict the dynamic response of the ship in wind and waves, and can more accurately evaluate the take-off and landing safety of ship-borne helicopters under high sea conditions, effectively improving the calculation accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

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

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

[0035] Figure 7 It is a schematic diagram of the force analysis of the hull side of the present invention. DETAILED DESCRIPTION

[0036] The present invention will be described below in conjunction with the accompanying drawings.

[0037] The present invention relates to a method for analyzing wind and wave loads and dynamic response of ships under short-peak wave sea conditions. The flow chart of the method is as follows: Figure 1 As shown, the following steps are included in sequence:

[0038] Parameter acquisition and coordinate system establishment steps: obtain wind and wave characteristic parameters and ship motion state parameters under different sea conditions, and establish a ground coordinate system with any point on the sea level as the origin, the ship motion direction as the longitudinal axis, the starboard side of the ship and parallel to the sea level as the transverse axis, and the center of the earth as the vertical axis; establish a hull stable coordinate system with the ship's center of mass as the origin, the ship motion direction as the longitudinal axis, the starboard side of the ship and parallel to the sea level as the transverse axis, and the center of the earth as the vertical axis; the wind and wave characteristic parameters include amplitude, wave number, main propagation direction of wind and waves, propagation direction of wind and wave harmonics, wind and wave angular frequency, time for wind and wave shape transformation, wind and wave natural period and wind and wave 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 in the figure, it is a fixed inertial coordinate system fixed to the earth, which is used to describe the motion state of the waves. Among them, the origin E of the coordinate system can be taken as any point on the sea level, the center of the earth is the vertical axis, that is, the Eζ axis points to the center of the earth, the direction of the ship's motion is the longitudinal axis, that is, the Eξ axis points to the direction of the ship's motion, the direction to the starboard of the ship and parallel to the sea level is the transverse axis, that is, the Eη axis points to the starboard of the ship and parallel to the sea level, the Eξ axis and the Eη axis are located in the sea level and are perpendicular to each other, and the distribution of the three coordinate axes conforms to the right-hand rule. The hull stable coordinate system Ox s y s z s like Figure 3 As shown in Figure 1, it is a coordinate system that moves with the ship and is used to describe the motion of the ship hull in a stable state. The origin of the coordinate system O is the center of mass of the ship, and the direction of motion of the ship is the longitudinal axis, that is, Ox s The axis points to the direction of the ship's motion, and the direction to the starboard side of the ship and parallel to the sea level is the transverse axis, that is, Oy s Pointing to the starboard side of the ship and parallel to the sea level, with the center of the earth as the vertical axis, 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.

[0040] The steps for constructing the short-peaked wave wind and wave model are as follows: In the ground coordinate system, a plane wave equation about the wave height is established based on the wave amplitude, wave number, the main propagation direction of wind and waves, the propagation direction of wind and wave harmonics, and the time of wind and wave shape transformation, and the short-peaked wave wind and wave model is obtained by recursively deducing the plane wave equation.

[0041] When a ship is sailing under high sea conditions, it will be disturbed by various marine environments such as waves, sea breezes, and ocean currents. Among them, random waves are the most important disturbance factor. Therefore, before analyzing the motion state of the ship under high sea conditions, it is very necessary to understand the distribution of random waves under high sea conditions. Specifically, wave simulation has always been a very complex problem. In real situations, the wind and waves on the sea surface are extremely complex irregular random three-dimensional waves, so it is very difficult to accurately model the waves. However, in the process of studying the problem of ship motion, it is considered that the wind and waves generally propagate in one direction along the wind direction, that is, the wind and waves only propagate along their main propagation direction (that is, the ξ axis of the ground coordinate system). Therefore, it can be assumed that the crests and troughs of the waves are parallel to each other and perpendicular to the wave propagation direction. At this time, assuming that the main propagation direction of the wind and waves is the ξ axis, the wave height (wave surface height) ζ at a fixed point on the sea surface is expressed as a binary function of ξ and time t ζ = ζ(ξ,t). According to the Longuet-Higgins model, the long-peak wave model of irregular wind waves can be regarded as the superposition of countless waves with different amplitudes (amplitudes), wavelengths and initial phases in the vertical plane of the main propagation direction of the wind waves. According to the following fluid mechanics assumptions:

[0042] a) The fluid is incompressible;

[0043] b) The fluid has only potential velocity;

[0044] c) The wind and waves are slight.

[0045] The plane wave propagating along the ξ axis can be expressed 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 mean sea level); ζ a is the amplitude; k is the wave number; λ is the wavelength, and the wave number is related to the wavelength: k = 2π / λ; ω is the angular frequency of wind waves. t is the time when the angular frequency of wind waves and the shape of wind waves change, describing the change of wind waves over time. When t = 0, its plane wave shape is as follows Figure 4 shown.

[0048] According to the plane wave formula, the long crest wave model (also called the Longuet-Higgins model of long crest waves) can be derived, as shown below:

[0049]

[0050] Among them, k i ,ω i , aiare the wave number, wind wave angular frequency and amplitude of the i-th harmonic respectively; ε i is the random initial phase of the i-th harmonic between 0 and 2π.

[0051] However, the above long-peak wave model still has problems such as being unable to accurately capture the propagation characteristics of waves and slow calculation speed because it only considers the main propagation direction of wind waves as the ξ axis. Therefore, the short-peak wave model of wind waves is introduced. This model considers that the propagation direction of different harmonics of wind waves will propagate along different propagation angles μ. It is defined that μ=0 when propagating along the ξ axis, and the angle μ is positive when rotating positively around the ζ axis according to the right-hand rule. Therefore, in the short-peak wave model of wind waves, the wave height ζ at a fixed point on the sea surface should be expressed as a three-variable function of ξ, η and time t ζ=ζ(ξ,η,t). The wave equation of the plane propagating at the propagation angle μ is re-described in the three-dimensional ground coordinate system E-ξηζ as follows:

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

[0053] Among them, a is the amplitude, k is the wave number, ζ is the wave height, μ represents the propagation angle, the propagation direction of different harmonics of wind and waves is along different propagation angles μ, the main propagation direction of wind and waves along the ξ axis, the main propagation direction of wind and waves along the η axis, ω is the angular frequency of wind and waves.

[0054] The short-peaked wave model (also called the Longuet-Higgins model of short-peaked wave) derived from the plane wave equation is as follows:

[0055]

[0056] The short-peaked wave model takes into account the main propagation direction of wind and waves along the ξ-axis and η-axis, and introduces the propagation direction of wind and wave harmonics as propagation along different propagation angles μ, so that the short-peaked wave model can more accurately capture the propagation characteristics of waves (including the propagation direction and energy distribution of wind and waves). And because the short-peaked wave model contains more degrees of freedom, it can more carefully characterize the irregularity of waves, thereby improving the accuracy of prediction, which is crucial for studying wave dynamics, marine engineering design and safety assessment. At the same time, the short-peaked wave model is also applicable to various complex marine environments, including wave conditions in different sea areas, seasons and weather conditions, and can better simulate the wind and wave behavior in the real world, providing a more reliable foundation for scientific research and engineering practice in related fields.

[0057] The wave surface equation and wave height calculation steps are as follows: the directional spectrum of short-peaked waves is calculated according to the propagation direction of wind and wave harmonics, and a first expression about the energy of long-peaked waves is constructed according to the wave amplitude and seawater density under ground coordinates, an angular frequency interval is established according to the wind and wave angular frequency and the bandwidth set based on the wind and wave angular frequency, and then a second expression about the energy of long-peaked waves within the angular frequency interval is obtained, and a third expression about the energy spectrum of long-peaked waves is recursively obtained from the second expression, and then the long-peaked wave energy spectrum is calculated; a short-peaked wave wind and wave spectrum is calculated according to the directional spectrum of short-peaked waves and the energy spectrum of long-peaked waves, a fourth expression about the energy of short-peaked waves is established based on the short-peaked wave wind and wave spectrum, and the fourth expression of the energy of short-peaked waves is calculated by the fourth expression and the short-peaked wave wind and wave model. 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 speed direction and the main propagation direction of the wind and waves is taken as the ship encounter angle, and a second relationship about the encounter period is established based on the ship encounter angle, the natural period of wind and waves, the natural wave speed of wind and waves and the ship speed, and a third relationship about the encounter angular frequency is established based on the ship encounter angle, the angular frequency of wind and waves, the natural wave speed of wind and waves and the ship speed; based on the first relationship, the second relationship and the third relationship, the coordinate and frequency transformation method is used to transform the first wave surface equation located in the ground coordinate system into the stable coordinate system of the hull, and the second wave surface equation applicable to the environment surrounding the ship is obtained, and the wave height encountered by the ship during navigation is calculated according to the second wave surface equation.

[0058] Specifically, the directional spectrum of short-peaked waves is first calculated according to the propagation direction of wind wave harmonics, and the calculation is performed according to the following formula:

[0059]

[0060] The 12th ITTC suggested that n in M(μ) be temporarily set to 1, then:

[0061]

[0062] Then, according to the knowledge of fluid mechanics, long-crest waves have energy. Therefore, in the ground coordinates, the first expression of the energy E of long-crest waves is constructed according to the wave amplitude and seawater density, which is expressed as follows:

[0063]

[0064] Where i is the harmonic order, ζ ai is the amplitude of the ith harmonic, ρ is the seawater density, and g is the gravitational acceleration.

[0065] According to the angular frequency of wind and waves ω and the bandwidth dω set based on the angular frequency of wind and waves, an angular frequency interval (ω, ω+dω) is established, and then a second expression for the energy of long crest waves in the angular frequency interval is obtained, which is expressed as follows:

[0066]

[0067] The third expression about the long-peak wave energy spectrum is derived from the second expression, that is, equation (8), which is defined as: ζ (ω) is shown in the following formula:

[0068]

[0069] According to formula 9, the long peak wave energy spectrum S can be calculated ζ (ω).

[0070] Preferably, when the bandwidth in the third expression tends to zero, that is, when dω→0, the integral expression of the long crest wave energy is calculated according to the first expression and the third expression, as shown below:

[0071]

[0072] According to the integral expression of long crest wave energy, the wave harmonic amplitude ζ can be obtained: ai With the spectral density function S ζ (ω) is related to:

[0073]

[0074] The short-peak wave wind wave spectrum is in the long-peak wave energy spectrum S ζ The directional spectrum of short-peaked waves M(μ) is added to the basis of (ω). Therefore, the short-peaked wave wind wave spectrum is calculated according to the directional spectrum of short-peaked waves and the energy spectrum of long-peaked waves, which is expressed as follows:

[0075] S ζ (ω,μ)=S ζ (ω)M(μ) (10)

[0076] The fourth expression for the energy of short-peaked waves is established based on the short-peaked wave spectrum, which is expressed as follows:

[0077]

[0078] Discretizing the above equation 11 and substituting it into the short crest wave wind wave model can obtain the first wave surface equation of the short crest wave wind wave, which is expressed as follows:

[0079]

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

[0081] When a ship is sailing on the sea, due to its certain speed, the wave frequency encountered by the ship is not the same as the wave frequency at a fixed point on the sea. When the ship is sailing against the waves, the wave frequency it encounters is higher than the wave frequency at a fixed point on the sea; conversely, when the ship is sailing with the waves, the wave frequency it encounters is lower than the wave frequency at a fixed point on the sea. Therefore, when studying the problem of ships sailing in wind and waves, we first define the wave period encountered by the ship as the encounter period T e , the corresponding angular frequency is called the encounter angular frequency ω e , which is related to the encounter period, establish the first relationship between the encounter period and the encounter angular frequency, that is, In addition, if Figure 5 As shown, the encounter period of the ship is T e and the encounter angular frequency ω e The natural period of the sea wave T, the angular frequency of the wind and wave ω (also called the natural angular frequency ω), the ship speed V, and the ship encounter angle μ e (the angle between the ship speed V and the wind and wave propagation direction) and the inherent wave speed C of the wind and waves, and the relationship can be expressed as:

[0082]

[0083] According to the above equations (13), (14) and the encounter period T e and the encounter angular frequency ω e The geometric relationship between the wave surface and the wave frequency is obtained by converting the first wave surface equation in the ground coordinate system, that is, equation (12), into the stable coordinate system of the hull through the coordinate and frequency transformation method (i.e., the coordinate transformation based on the rotation matrix and the transformation from the wave frequency to the encounter frequency). The second wave surface equation suitable for the short-peaked waves in the surrounding environment of the ship is obtained, which is expressed as follows:

[0084]

[0085] According to the second wave surface equation of short-peaked wind waves, that is, according to formula (15), the wave height ζ encountered by the ship during navigation can be calculated: e , which indicates the shape of the wave surface encountered by the ship during navigation, can more accurately reflect the actual wave conditions, especially for the accurate prediction of wave height under complex sea conditions, reducing the risk of ships encountering extreme sea conditions, thereby protecting the safety of the ship and its crew.

[0086] Steps for obtaining a multi-wave superposition fluctuation pressure model: in a stable coordinate system of the hull, calculate the sea surface depth of a certain underwater point from the free liquid surface according to the liquid surface depth under still water conditions and the wave height encountered by the ship during navigation, and construct a fifth expression for the pressure at a certain underwater point according to the sea surface depth and the atmospheric pressure; calculate a sixth expression for the pressure at a certain underwater point under short-peak wave and sea wave conditions according to the fifth expression and the short-peak wave wind and wave model; obtain a fluctuation pressure model caused by sea waves according to the sixth expression, and use the Smith correction term method to correct the fluctuation pressure model to obtain a corrected fluctuation pressure model; and express the corrected fluctuation pressure model as a superposition of multiple cosine waves through the harmonic superposition analysis method to obtain a multi-wave superposition fluctuation pressure model.

[0087] Specifically, this step can also be understood as a step for studying the distribution of the seawater pressure field under the sea surface. During the research process, it is generally believed that the interference force and torque of the waves on the hull are caused by the fluctuation of the pressure field distribution under the liquid surface. Therefore, before analyzing the wind and wave forces and torques on the ship, the distribution of the seawater pressure field under the sea surface is first studied. From the basic water pressure formula, it can be seen that 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 the atmospheric pressure; ρ is the density of seawater; g is the acceleration of gravity; and h is the depth of a certain point underwater (also called a 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] According to the fifth expression and the short-peak wave wind wave model, the sixth expression of the pressure at a certain point underwater under the condition of short-peak wave sea waves is calculated. That is, the sixth expression of the pressure at a certain point underwater under the condition of long-peak wave sea waves is obtained by substituting equation (4) into equation (16), as shown in the following equation:

[0092] P=P0+ρgz+ρgζ a cos(kξ-ωt) (18)

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

[0094] ΔP=ρgζ a cos(kξ-ωt) (19)

[0095] According to the Smith effect, the amplitude of the wave surface fluctuation is affected by the depth, so the Smith correction term is used to correct the fluctuation pressure model to obtain the corrected fluctuation pressure model, as shown in the following formula:

[0096]

[0097]

[0098] ΔP=e -kz ρgζ a cos(kξ-ωt) (22)

[0099] Expanded in the hull 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 fluctuating pressure model is expressed as the superposition of multiple cosine waves through the harmonic superposition analysis method, and the multi-wave superposition fluctuating pressure model is obtained, that is, formula (23) is expressed as the cosine wave superposition form, as shown in the following formula:

[0102]

[0103] Calculation steps of disturbance force and disturbance moment: calculate the wave pressure on the ship according to the multi-wave superposition wave pressure model, and integrate the wave pressure on the ship to obtain the heave disturbance force of the ship; then integrate the heave disturbance force in the direction of the pitch axis of the hull to obtain the pitch disturbance moment on the pitch direction of the ship; integrate the heave disturbance force in the bottom direction, left direction and right direction of the roll axis of the hull respectively to obtain the bottom component, left side component and right side component of the roll disturbance moment on the roll direction of the ship; calculate the roll disturbance moment according to the bottom component, left side component and right side component of the roll disturbance moment to complete the analysis of wind and wave load and dynamic response of the ship.

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

[0105] 1) Wind and wave forces and moments are caused only by fluid pressure;

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

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

[0108] According to the Froud-Krylov hypothesis, the wave pressure ΔP caused by the waves shown in equation (24) is integrated on each underwater surface of the hull to obtain the wind and wave force and moment. In engineering, since the shape of the ship itself is often complex, when there is no detailed ship line drawing, the hull can be approximated as L, B, and H, respectively. Relatively accurate results can still be obtained by calculating wind and wave forces and moments on a rectangular block.

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

[0110]

[0111] Then the heave disturbance force is integrated along the direction of the pitch axis of the hull to obtain the pitch disturbance moment M of the ship in the pitch direction: w , which can also be understood as the vertical disturbance force Z w Take the moment of the ship's pitch axis to get the ship's pitch disturbance moment M w , as shown below:

[0112]

[0113] Then the heave disturbance force is integrated according to the bottom direction, left direction and right direction of the hull roll axis, and the bottom component, left side component and right side component of the roll disturbance moment of the ship in the roll direction are obtained respectively. Among them, the bottom component K of the ship roll disturbance moment is w1 The moment of the hull roll axis is obtained by the heave disturbance force, as shown in the following formula:

[0114]

[0115] Hull side force analysis Figure 7 As shown in the figure, the right side component of the ship's roll disturbance moment can be obtained by taking the moment of the sway disturbance force on the ship's roll axis, as shown in the following formula:

[0116]

[0117] Left side component K w3 Similarly, according to the bottom component K of the rolling disturbance moment, w1 , left side component K w3and the right side component K w2 Calculate the roll disturbance moment, roll disturbance moment K w for:

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

[0119] The present invention also relates to a ship wind and wave load and dynamic response analysis system under short-peak wave sea conditions. The system corresponds to the above-mentioned ship wind and wave load and dynamic response analysis method under short-peak wave sea conditions, 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 short-peak wave wind and wave model construction module, a wave surface equation and sea wave height calculation module, a multi-wave superposition fluctuation pressure model acquisition module, and an interference force and interference torque calculation module connected in sequence. Specifically,

[0120] The parameter acquisition and coordinate system establishment module acquires wind and wave characteristic parameters and ship motion state parameters under different sea conditions, and establishes a ground coordinate system with any point on the sea level as the origin, the ship motion direction as the horizontal coordinate, the direction of the starboard side of the ship parallel to the sea level as the vertical coordinate, and the center of the earth as the vertical coordinate; establishes a hull stable coordinate system with the ship's center of mass as the origin, the ship motion direction as the horizontal coordinate, the direction of the starboard side of the ship parallel to the sea level as the vertical coordinate, and the center of the earth as the vertical coordinate; the wind and wave characteristic parameters include 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, wind and wave natural period, and wind and wave natural wave speed; the ship's motion state parameters include ship speed, encounter period, and encounter angular frequency;

[0121] The short-peaked wave wind and wave model construction module establishes a plane wave equation about the wave height in the ground coordinate system based on the wave amplitude, wave number, main propagation direction of wind and waves, propagation direction of wind and wave harmonics, and time of wind and wave shape transformation, and recursively obtains the short-peaked wave wind and wave model according to the plane wave equation;

[0122] The wave surface equation and wave height calculation module calculates the directional spectrum of short-peaked waves according to the propagation direction of wind and wave harmonics, and constructs a first expression for the energy of long-peaked waves according to the wave amplitude and seawater density under ground coordinates, establishes an angular frequency interval according to the wind and wave angular frequency and the frequency band width set based on the wind and wave angular frequency, and then obtains a second expression for the energy of long-peaked waves within the angular frequency interval, and recursively obtains a third expression for the energy spectrum of long-peaked waves from the second expression, and then calculates the energy spectrum of long-peaked waves; calculates the short-peaked wave wind and wave spectrum according to the directional spectrum of short-peaked waves and the long-peaked wave energy spectrum, establishes a fourth expression for the energy of short-peaked waves based on the short-peaked wave wind and wave spectrum, and calculates the short-peaked wave wind and wave model by the fourth expression. The first wave surface equation; then establish a first relationship between the encounter period and the encounter angular frequency, and take the angle between the ship speed direction and the main propagation direction of the wind and waves as the ship encounter angle, and establish a second relationship about the encounter period based on the ship encounter angle, the natural period of wind and waves, the natural wave speed of wind and waves, and the ship speed, and establish a third relationship about the encounter angular frequency based on the ship encounter angle, the angular frequency of wind and waves, the natural wave speed of wind and waves, and the ship speed; based on the first relationship, the second relationship, and the third relationship, and using the coordinate and frequency transformation method, the first wave surface equation located in the ground coordinate system is converted into the hull stable coordinate system, and the second wave surface equation applicable to the surrounding environment of the ship is obtained, and the wave height encountered by the ship during navigation is calculated according to the second wave surface equation;

[0123] The multi-wave superposition fluctuation pressure model acquisition module calculates the sea surface depth of a certain underwater point from the free liquid surface according to the liquid surface depth under calm water conditions and the wave height encountered by the ship during navigation in a stable coordinate system of the hull, and constructs a fifth expression for the pressure of a certain underwater point according to the sea surface depth and the atmospheric pressure; calculates a sixth expression for the pressure of a certain underwater point under short-peak wave and sea wave conditions according to the fifth expression and the short-peak wave wind and wave model; obtains the fluctuation pressure model caused by the sea waves according to the sixth expression, and corrects the fluctuation pressure model by using the Smith correction term method to obtain the corrected fluctuation pressure model; and expresses the corrected fluctuation pressure model as the superposition of multiple cosine waves by using the harmonic superposition analysis method to obtain the multi-wave superposition fluctuation pressure model;

[0124] The disturbance force and disturbance torque calculation module calculates the wave pressure received by the ship according to the multi-wave superposition wave pressure model, and based on the Froud-Krylov hypothesis and the square ship hypothesis, integrates the wave pressure received by the ship at the bottom of the ship to obtain the heave disturbance force of the ship; then integrates the heave disturbance force in the direction of the hull pitch axis to obtain the pitch disturbance torque received by the ship in the pitch direction; integrates the heave disturbance force in the bottom direction, left direction and right direction of the hull roll axis respectively to obtain the bottom component, left side component and right side component of the roll disturbance torque received by the ship in the roll direction; calculates the roll disturbance torque according to the bottom component, left side component and right side component of the roll disturbance torque, so as to complete the ship wind and wave load and dynamic response analysis.

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

[0126] 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.

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

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

[0129] It should be noted that the above-described specific implementations can enable those skilled in the art to more fully understand the invention, but do not limit the invention in any way. Therefore, although this specification has described the invention in detail with reference to the drawings and embodiments, those skilled in the art should understand that the invention can still be modified or replaced by equivalents. In short, all technical solutions and improvements that do not deviate from the spirit and scope of the invention should be included in the protection scope of the patent for the invention.

Claims

1. A method for analyzing wind and wave loads and dynamic responses of ships under short-peak wave sea conditions, characterized in that: The following steps are involved: Parameter acquisition and coordinate system establishment steps: obtain wind and wave characteristic parameters and ship motion state parameters under different sea conditions, and establish a ground coordinate system with any point on the sea level as the origin, the ship motion direction as the horizontal coordinate, the direction of the starboard side of the ship parallel to the sea level as the vertical coordinate, and the center of the earth as the vertical coordinate; establish a hull stable coordinate system with the ship's center of mass as the origin, the ship motion direction as the horizontal coordinate, the direction of the starboard side of the ship parallel to the sea level as the vertical coordinate, and the center of the earth as the vertical coordinate; the wind and wave characteristic parameters include 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, wind and wave natural period and wind and wave natural wave speed; the ship's motion state parameters include ship speed, encounter period and encounter angular frequency; The steps of constructing the short-peaked wave wind and wave model are as follows: in the ground coordinate system, a plane wave equation about the wave height is established based on the wave amplitude, wave number, main propagation direction of wind and wave, propagation direction of wind and wave harmonics, and the time of wind and wave shape transformation, and the short-peaked wave wind and wave model is obtained by recursion based on the plane wave equation; The wave surface equation and wave height calculation steps are as follows: the directional spectrum of short-peaked waves is calculated according to the propagation direction of wind and wave harmonics, and a first expression about the energy of long-peaked waves is constructed according to the wave amplitude and seawater density under ground coordinates, an angular frequency interval is established according to the wind and wave angular frequency and the bandwidth set based on the wind and wave angular frequency, and then a second expression about the energy of long-peaked waves within the angular frequency interval is obtained, and a third expression about the energy spectrum of long-peaked waves is recursively obtained from the second expression, and then the long-peaked wave energy spectrum is calculated; a short-peaked wave wind and wave spectrum is calculated according to the directional spectrum of short-peaked waves and the energy spectrum of long-peaked waves, a fourth expression about the energy of short-peaked waves is established based on the short-peaked wave wind and wave spectrum, and the fourth expression of the energy of short-peaked waves is calculated by the fourth expression and the short-peaked wave wind and wave model. A wave surface equation is established; then a first relational expression between the encounter period and the encounter angular frequency is established, and the angle between the ship speed direction and the main propagation direction of the wind and waves is taken as the ship encounter angle, and a second relational expression about the encounter period is established based on the ship encounter angle, the natural period of the wind and waves, the natural wave speed of the wind and waves, and the ship speed, and a third relational expression about the encounter angular frequency is established based on the ship encounter angle, the angular frequency of the wind and waves, the natural wave speed of the wind and waves, and the ship speed; based on the first relational expression, the second relational expression and the third relational expression, and using the coordinate and frequency transformation method, the first wave surface equation located in the ground coordinate system is converted into the hull stable coordinate system, and a second wave surface equation applicable to the surrounding environment of the ship is obtained, and the wave height encountered by the ship during navigation is calculated according to the second wave surface equation; The steps of obtaining the multi-wave superposition fluctuation pressure model are as follows: in the hull stable coordinate system, the sea surface depth of a certain underwater point from the free liquid surface is calculated according to the liquid surface depth under calm water conditions and the wave height encountered by the ship during navigation, and the fifth expression about the pressure of a certain underwater point is constructed according to the sea surface depth and the atmospheric pressure; the sixth expression of the pressure of a certain underwater point under the short-peak wave and sea wave conditions is calculated according to the fifth expression and the short-peak wave wind and wave model; The fluctuating pressure model caused by the ocean waves is obtained according to the sixth expression, and the fluctuating pressure model is corrected by using the Smith correction term method to obtain the corrected fluctuating pressure model; and the corrected fluctuating pressure model is expressed as the superposition of multiple cosine waves by using the harmonic superposition analysis method to obtain the multi-wave superposition fluctuating pressure model; Calculation steps of disturbance force and disturbance moment: Calculate the wave pressure on the ship according to the multi-wave superposition wave pressure model, and based on the Froud-Krylov hypothesis and the square ship hypothesis, integrate the wave pressure on the ship at the bottom of the ship to obtain the heave disturbance force of the ship; then integrate the heave disturbance force in the direction of the hull pitch axis to obtain the pitch disturbance moment on the ship in the pitch direction; integrate the heave disturbance force in the bottom direction, left direction and right direction of the hull roll axis respectively to obtain the bottom component, left side component and right side component of the roll disturbance moment on the ship in the roll direction; The roll disturbance moment is calculated according to the bottom component, left side component and right side component of the roll disturbance moment to complete the analysis of ship wind and wave load and dynamic response.

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

3. The method for analyzing wind and wave loads and dynamic responses of ships under short-peak wave sea conditions according to claim 1 is 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 wind and wave loads and dynamic responses of ships under short-peak wave sea conditions according to claim 1 is characterized in that: The coordinate and frequency change method includes coordinate transformation based on rotation matrix and transformation from wave frequency to encounter frequency.

5. A system for analyzing wind and wave loads and dynamic responses of ships under short-peak wave sea conditions, characterized in that: It includes a parameter acquisition and coordinate system establishment module, a short-peak wave wind and 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 conditions, and establishes a ground coordinate system with any point on the sea level as the origin, the ship motion direction as the horizontal coordinate, the direction of the starboard side of the ship parallel to the sea level as the vertical coordinate, and the center of the earth as the vertical coordinate; establishes a hull stable coordinate system with the ship's center of mass as the origin, the ship motion direction as the horizontal coordinate, the direction of the starboard side of the ship parallel to the sea level as the vertical coordinate, and the center of the earth as the vertical coordinate; the wind and wave characteristic parameters include 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, wind and wave natural period, and wind and wave natural wave speed; the ship's motion state parameters include ship speed, encounter period, and encounter angular frequency; The short-peaked wave wind and wave model construction module establishes a plane wave equation about the wave height in the ground coordinate system based on the wave amplitude, wave number, main propagation direction of wind and waves, propagation direction of wind and wave harmonics, and time of wind and wave shape transformation, and recursively obtains the short-peaked wave wind and wave model according to the plane wave equation; The wave surface equation and wave height calculation module calculates the directional spectrum of short-peaked waves according to the propagation direction of wind and wave harmonics, and constructs a first expression for the energy of long-peaked waves according to the wave amplitude and seawater density under ground coordinates, establishes an angular frequency interval according to the wind and wave angular frequency and the frequency band width set based on the wind and wave angular frequency, and then obtains a second expression for the energy of long-peaked waves within the angular frequency interval, and recursively obtains a third expression for the energy spectrum of long-peaked waves from the second expression, and then calculates the energy spectrum of long-peaked waves; calculates the short-peaked wave wind and wave spectrum according to the directional spectrum of short-peaked waves and the long-peaked wave energy spectrum, establishes a fourth expression for the energy of short-peaked waves based on the short-peaked wave wind and wave spectrum, and calculates the short-peaked wave wind and wave model by the fourth expression. The first wave surface equation; then establish a first relationship between the encounter period and the encounter angular frequency, and take the angle between the ship speed direction and the main propagation direction of the wind and waves as the ship encounter angle, and establish a second relationship about the encounter period based on the ship encounter angle, the natural period of wind and waves, the natural wave speed of wind and waves, and the ship speed, and establish a third relationship about the encounter angular frequency based on the ship encounter angle, the angular frequency of wind and waves, the natural wave speed of wind and waves, and the ship speed; based on the first relationship, the second relationship, and the third relationship, and using the coordinate and frequency transformation method, the first wave surface equation located in the ground coordinate system is converted into the hull stable coordinate system, and the second wave surface equation applicable to the surrounding environment of the ship is obtained, and the wave height encountered by the ship during navigation is calculated according to the second wave surface equation; The multi-wave superposition fluctuation pressure model acquisition module calculates the sea surface depth of a certain underwater point from the free liquid surface according to the liquid surface depth under calm water conditions and the wave height encountered by the ship during navigation in the hull stable coordinate system, and constructs a fifth expression for the pressure of a certain underwater point according to the sea surface depth and the atmospheric pressure; calculates a sixth expression for the pressure of a certain underwater point under short-peak wave conditions according to the fifth expression and the short-peak wave wind and wave model; The fluctuating pressure model caused by the ocean waves is obtained according to the sixth expression, and the fluctuating pressure model is corrected by using the Smith correction term method to obtain the corrected fluctuating pressure model; and the corrected fluctuating pressure model is expressed as the superposition of multiple cosine waves by using the harmonic superposition analysis method to obtain the multi-wave superposition fluctuating pressure model; The interference force and interference torque calculation module calculates the wave pressure received by the ship according to the multi-wave superposition wave pressure model, and based on the Froud-Krylov hypothesis and the square ship hypothesis, integrates the wave pressure received by the ship at the bottom of the ship to obtain the heave interference force of the ship; then integrates the heave interference force in the direction of the hull pitch axis to obtain the pitch interference torque received by the ship in the pitch direction; integrates the heave interference force in the bottom direction, left direction and right direction of the hull roll axis respectively to obtain the bottom component, left side component and right side component of the roll interference torque received by the ship in the roll direction; The roll disturbance moment is calculated according to the bottom component, left side component and right side component of the roll disturbance moment to complete the analysis of ship wind and wave load and dynamic response.

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

7. The ship wind and wave load and dynamic response analysis system under short-peak wave sea conditions according to claim 5 is characterized in that: 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.

8. The ship wind and wave load and dynamic response analysis system under short-peak wave sea conditions according to claim 5 is characterized in that: The coordinate and frequency transformation method includes coordinate transformation based on rotation matrix and transformation from wave frequency to encounter frequency.

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