A method for calculating wave loads on LNG moored ships

Abstract

The present invention relates to the technical field of moored ships, and in particular to a method for calculating wave loads of LNG moored ships. The method comprises: obtaining ship parameters and wave parameters of a target ship; calculating an estimated lateral force and an estimated longitudinal force of the target ship according to the wave parameters, the ship parameters and a preset wave force comprehensive coefficient; calculating a maximum mooring force, a wind load and a water flow load on the target ship; calculating the lateral wave force and the longitudinal wave force of the target ship according to the maximum mooring force, the wind load and the water flow load; respectively comparing the estimated lateral force and the estimated longitudinal force with the lateral wave force and the longitudinal wave force, and if the difference between the two is greater than or equal to a preset threshold, adjusting the wave force comprehensive coefficient and recalculating, otherwise calculating the wave load of the target ship according to the current wave force comprehensive coefficient; the present invention can effectively improve the accuracy of wave load calculation, and is suitable for wave load analysis of different types of LNG ships in a moored state.

Description

Technical Field

[0001] The present invention relates to the technical field of moored ships, and in particular to a method for calculating wave loads of LNG moored ships. Background Art

[0002] When LNG ships are berthing at the dock, the ship's mooring force directly affects the safety of the ship and the dock structure. Traditional mooring force calculation methods and design specifications usually consider the effects of wind and water flow forces, but do not consider the impact of wave loads on ships. In fact, the lateral and longitudinal forces generated by wave loads on ships are significant in complex marine environments, which may cause unstable ship movement, increase the stress on the cables, and thus increase the risk of cable breakage, endangering the safety of ships and docks.

[0003] Existing wave load calculation methods are usually based on model test data and empirical formulas, the accuracy of which depends on the determination of comprehensive coefficients. However, due to the complexity of wave loads and the diversity of different ships and sea conditions, existing methods often have errors in the calculation process and are difficult to fully adapt to different types of LNG ships and changing marine environments.

[0004] Therefore, there is an urgent need for a wave load calculation method for LNG moored ships, which can effectively improve the accuracy of wave load calculation and is suitable for wave load analysis of different types of LNG ships in moored states. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for calculating wave loads on LNG moored ships, which can effectively improve the accuracy of wave load calculation and is suitable for wave load analysis of different types of LNG ships in moored states.

[0006] The present invention provides a method for calculating wave loads of an LNG moored ship, comprising the following steps:

[0007] S1. Obtaining ship parameters and wave parameters of the target ship;

[0008] S2, substituting wave parameters, ship parameters and preset wave force comprehensive coefficient into the estimation formula to calculate the estimated lateral force and estimated longitudinal force of the target ship under the action of waves;

[0009] S3. Obtain the maximum mooring force on the target ship through model tests;

[0010] S4. Obtain hydrological conditions through a hydrological monitoring system, and calculate the wind load and current load on the target ship according to the hydrological conditions;

[0011] S5. Calculate the transverse wave force and longitudinal wave force on the target ship according to the maximum mooring force, wind load and current load;

[0012] S6. Compare the estimated lateral force with the lateral wave force, and compare the estimated longitudinal force with the longitudinal wave force. If the difference between the estimated lateral force and the lateral wave force is greater than or equal to the preset threshold or the difference between the estimated longitudinal force and the longitudinal wave force is greater than or equal to the preset threshold, return to S2. If the difference between the estimated lateral force and the lateral wave force is less than the preset threshold and the difference between the estimated longitudinal force and the longitudinal wave force is less than the preset threshold, calculate the wave load of the target ship according to the current wave force comprehensive coefficient and the estimation formula.

[0013] Further, in S2, the preset wave force comprehensive coefficient includes a preset lateral wave force comprehensive coefficient and a preset longitudinal wave force comprehensive coefficient;

[0014] Among them, the preset comprehensive coefficient of lateral wave force is 0.05; the preset comprehensive coefficient of longitudinal wave force is 0.05.

[0015] Further, in S2, the wave parameters, ship parameters and the preset wave force comprehensive coefficient are substituted into the estimation formula to calculate the estimated lateral force and the estimated longitudinal force of the target ship under the action of the waves, specifically including:

[0016] The estimated lateral force of the target ship under the action of waves is estimated as follows:

[0017] ;

[0018] Among them, F x represents the estimated lateral force, x represents the comprehensive coefficient of lateral wave force, H represents the incident wave height, θ represents the wave incident angle, L represents the length between the ship columns, D represents the ship draft, and a x represents the lateral magnification factor, γ represents the seawater density, and g represents the gravitational acceleration;

[0019] The estimation formula for the estimated longitudinal force of the target ship under the action of waves is as follows:

[0020] ;

[0021] Among them, F y represents the estimated longitudinal force, y represents the comprehensive coefficient of longitudinal wave force, B represents the ship width, a y Represents the longitudinal magnification factor.

[0022] Furthermore, the calculation formula of the lateral magnification factor is as follows:

[0023] ;

[0024] Among them, T x represents the rolling period of the ship, T represents the wave period, μ xrepresents the lateral damping coefficient;

[0025] The calculation formula of the longitudinal magnification factor is as follows:

[0026] ;

[0027] Among them, T y represents the pitch period of the ship, μ y represents the longitudinal damping coefficient.

[0028] Furthermore, in S4, the hydrological conditions are obtained through the hydrological monitoring system, and the wind load on the target ship is calculated according to the hydrological conditions. The calculation formula is as follows:

[0029] ;

[0030] ;

[0031] Among them, F xw represents the lateral component of wind load, F yw represents the longitudinal component of wind load, A xw Indicates the lateral windward area above the water surface of the hull, A yw It represents the longitudinal windward area above the water surface of the hull, v x represents the lateral component of wind speed, v y represents the longitudinal component of wind speed, represents the wind pressure unevenness reduction coefficient, Indicates the correction factor for wind pressure height change.

[0032] Furthermore, in S4, the hydrological conditions are obtained through the hydrological monitoring system, and the flow load on the target ship is calculated according to the hydrological conditions. The calculation formula is as follows:

[0033] ;

[0034] ;

[0035] Among them, F TC represents the lateral component of the flow load, F LC represents the longitudinal component of the water flow load, C TC represents the lateral component coefficient of water flow force, ρ represents the density of water, V c Indicates the average flow velocity within the ship's draft depth, L BP represents the length between vertical lines of the ship, D' represents the average draft corresponding to the loading degree of the ship, θ c Indicates the angle between the water flow direction and the longitudinal axis of the ship, F LCP represents the longitudinal force component caused by form drag, F LCf Represents the longitudinal component of force caused by frictional resistance.

[0036] Furthermore, in S5, the transverse wave force and the longitudinal wave force on the target ship are calculated according to the maximum mooring force, the wind load and the current load, specifically including:

[0037] S51, calculating the lateral component of the maximum mooring force perpendicular to the front line of the wharf and the longitudinal component of the maximum mooring force parallel to the front line of the wharf according to the maximum mooring force;

[0038] The calculation formula is as follows:

[0039] ;

[0040] ;

[0041] Among them, N x Indicates the lateral component of the maximum mooring force perpendicular to the front line of the pier, N y represents the longitudinal component of the maximum mooring force parallel to the front line of the pier, N represents the maximum mooring force, α represents the angle between the horizontal projection of the mooring cable and the front line of the pier, and β represents the angle between the mooring cable and the horizontal plane;

[0042] S52, calculating the lateral wave force on the target ship according to the lateral component of the maximum mooring force, the lateral component of the wind load, and the lateral component of the current load;

[0043] The calculation formula is as follows:

[0044] ;

[0045] Among them, F x ' represents the transverse wave force;

[0046] S53, calculating the longitudinal wave force on the target ship according to the longitudinal component of the maximum mooring force, the longitudinal component of the wind load, and the longitudinal component of the current load;

[0047] The calculation formula is as follows:

[0048] ;

[0049] Among them, F y ' represents the transverse wave force.

[0050] The present invention also provides a LNG moored ship wave load calculation system, which is used to implement the above-mentioned LNG moored ship wave load calculation method, and the system includes the following modules:

[0051] A data acquisition module, used to acquire ship parameters and wave parameters of the target ship;

[0052] The wave force estimation module is connected to the data acquisition module and is used to substitute the wave parameters, the ship parameters and the preset wave force comprehensive coefficient into the estimation formula to calculate the estimated lateral force and the estimated longitudinal force of the target ship under the action of the waves;

[0053] The mooring force calculation module is used to obtain the maximum mooring force on the target ship through model tests;

[0054] The wind load and water flow load calculation module is used to obtain hydrological conditions through the hydrological monitoring system and calculate the wind load and water flow load on the target ship according to the hydrological conditions;

[0055] A wave force calculation module is connected to the mooring force calculation module and the wind load and water flow load calculation module, and is used to calculate the transverse wave force and longitudinal wave force on the target ship according to the maximum mooring force, wind load and water flow load;

[0056] The formula correction module is connected to the wave force estimation module and the wave force calculation module, and is used to compare the estimated lateral force with the lateral wave force, and to compare the estimated longitudinal force with the longitudinal wave force, respectively. If the difference between the estimated lateral force and the lateral wave force is greater than or equal to a preset threshold or the difference between the estimated longitudinal force and the longitudinal wave force is greater than or equal to the preset threshold, the wave force comprehensive coefficient is adjusted, and the estimated lateral force and the estimated longitudinal force of the target ship under the action of waves are recalculated. If the difference between the estimated lateral force and the lateral wave force is less than the preset threshold and the difference between the estimated longitudinal force and the longitudinal wave force is less than the preset threshold, the wave load of the target ship is calculated according to the current wave force comprehensive coefficient and the estimation formula.

[0057] The embodiments of the present invention have the following technical effects:

[0058] The present invention collects test data on the motion model of LNG ships under the action of waves, establishes an empirical formula in combination with a comprehensive coefficient, and continuously corrects the comprehensive coefficient by comparing the calculated value with the actual test value, and finally obtains a calculation formula that can accurately calculate the wave load of the ship.

[0059] This method is based on the combination of measured data and theoretical analysis, and can quickly calculate the wave load of moored ships. It not only improves the accuracy of wave loads, but also can be widely applied to the analysis and calculation of wave loads of different LNG ships. It can statistically summarize the comprehensive coefficients of different ship types under different wave conditions. When the wave load needs to be calculated for the mooring design and operation of ships, it supplements the wave load calculation content that is currently missing in the "Port Engineering Load Code". In addition, the calculation process of this method is easy to understand and operate, does not require complex computing equipment and software, and is suitable for wide application in engineering practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0061] Figure 1 is a flow chart of a method for calculating wave loads of an LNG moored ship provided by an embodiment of the present invention;

[0062] Figure 2 It is a logic diagram of a method for calculating wave loads of an LNG moored ship provided by an embodiment of the present invention;

[0063] Figure 3 It is a structural schematic diagram of a wave load calculation system for an LNG moored vessel provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0064] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0065] Wave load refers to the force exerted by the ship on the cable due to the action of waves, which is expressed as the longitudinal force parallel to the hull and the lateral force perpendicular to the hull. The embodiment of the present invention provides a method for calculating the wave load of an LNG moored ship. Figure 1 is a flow chart of a method for calculating wave loads on an LNG moored ship provided in an embodiment of the present invention. Figure 2 is a logic diagram of a method for calculating wave loads on an LNG moored ship provided in an embodiment of the present invention, see Figure 1 and Figure 2 , including:

[0066] S1. Obtain ship parameters and wave parameters of the target ship.

[0067] For example, the hydrological conditions of the ship at the actual dock can be collected based on the conditions at the dock, such as the ship parameters of the actual ship that will dock at the dock. When conducting tests on the target ship, the ship parameters and wave parameters of the target ship model can be obtained by converting them according to the corresponding scale.

[0068] S2. Substitute the wave parameters, ship parameters and preset wave force comprehensive coefficient into the estimation formula to calculate the estimated lateral force and estimated longitudinal force of the target ship under the action of waves.

[0069] Among them, the preset comprehensive wave force coefficient includes a preset comprehensive lateral wave force coefficient and a preset comprehensive longitudinal wave force coefficient, the comprehensive lateral wave force coefficient and the comprehensive longitudinal wave force coefficient are dimensionless numbers. Preferably, the preset comprehensive lateral wave force coefficient is 0.05; the preset comprehensive longitudinal wave force coefficient is 0.05.

[0070] Specifically, the estimation formula for the estimated lateral force of the target ship under the action of waves is as follows:

[0071] ;

[0072] Among them, F x represents the estimated lateral force, x represents the comprehensive coefficient of lateral wave force, H represents the incident wave height, θ represents the wave incident angle (the angle between the wave direction and the longitudinal axis of the ship), L represents the length between the ship columns, D represents the draft of the ship, and a x It represents the lateral magnification factor, which is a parameter reflecting the relationship between the ship's rolling and the wave period. γ represents the seawater density, which is 1025 kg / m 3 , g represents the acceleration due to gravity, which is 9.81 m / s 2 ;

[0073] The estimation formula for the estimated longitudinal force of the target ship under the action of waves is as follows:

[0074] ;

[0075] Among them, F y represents the estimated longitudinal force, y represents the comprehensive coefficient of longitudinal wave force, B represents the ship width, a y It represents the longitudinal amplification factor, which is a parameter reflecting the relationship between the ship's pitch and the wave period.

[0076] When the test data is not available, the preset lateral wave force comprehensive coefficient of 0.05 and the preset longitudinal wave force comprehensive coefficient of 0.05 are substituted into the estimation formula to calculate the estimated lateral force and the estimated longitudinal force.

[0077] Furthermore, the calculation formula of the lateral magnification factor is as follows:

[0078] ;

[0079] Among them, T x represents the rolling period of the ship, T represents the wave period, μ x represents the lateral damping coefficient;

[0080] The calculation formula of the longitudinal magnification factor is as follows:

[0081] ;

[0082] Among them, T y represents the pitch period of the ship, μ y represents the longitudinal damping coefficient.

[0083] Furthermore, the calculation formula of the lateral damping coefficient is as follows:

[0084] ;

[0085] Where W represents the actual displacement of the ship, W f Indicates the ship's full load displacement;

[0086] The calculation formula of the longitudinal damping coefficient is as follows:

[0087] ;

[0088] Specifically, the damping coefficient is calculated based on experience. For important projects, the damping coefficient also needs to be corrected in order to find a more reasonable comprehensive coefficient and damping coefficient. In some embodiments, correction content for the damping coefficient may also be added.

[0089] S3. Obtain the maximum mooring force on the target ship through model tests.

[0090] Specifically, when the mooring force reaches its maximum, the ship is in force balance and relatively static, and the maximum mooring force is equal to the sum of wave load, wind load and current load.

[0091] S4. Obtain hydrological conditions through a hydrological monitoring system, and calculate the wind load and current load on the target ship based on the hydrological conditions.

[0092] Specifically, the calculation formula for the wind load on the target ship is as follows:

[0093] ;

[0094] ;

[0095] Among them, F xw represents the lateral component of wind load, F yw represents the longitudinal component of wind load, A xw Indicates the lateral windward area above the water surface of the hull, A yw It represents the longitudinal windward area above the water surface of the hull, v x represents the lateral component of wind speed, v y represents the longitudinal component of wind speed, represents the wind pressure unevenness reduction coefficient, Indicates the correction factor for wind pressure height change.

[0096] The calculation formula of the water flow load on the target ship is as follows:

[0097] ;

[0098] ;

[0099] Among them, F TC represents the lateral component of the flow load, F LC represents the longitudinal component of the water flow load, C TC represents the lateral component coefficient of water flow force, ρ represents the density of water, V c Indicates the average flow velocity within the ship's draft depth, L BP represents the length between vertical lines of the ship, D' represents the average draft corresponding to the loading degree of the ship, θ c Indicates the angle between the water flow direction and the longitudinal axis of the ship, F LCP represents the longitudinal force component caused by form drag, F LCf Represents the longitudinal component of force caused by frictional resistance.

[0100] Furthermore, the calculation formula of the longitudinal force generated by the shape resistance is as follows:

[0101] ;

[0102] Among them, C LCP It represents the longitudinal shape resistance coefficient of the ship;

[0103] The calculation formula of the longitudinal force generated by friction resistance is as follows:

[0104] ;

[0105] Among them, C LCf represents the friction resistance coefficient of the hull, and S represents the surface area below the waterline of the ship.

[0106] Furthermore, the calculation formula of the hull friction resistance coefficient is as follows:

[0107] ;

[0108] ;

[0109] ;

[0110] Where Re is the Reynolds number of the water flow acting on the ship, ΔC LCf Indicates the hull roughness correction factor, L WL Indicates the length of the ship's waterline, C b represents the block coefficient of the ship, and v represents the kinematic viscosity coefficient of water.

[0111] S5. Calculate the transverse wave force and longitudinal wave force acting on the target ship according to the maximum mooring force, wind load and current load.

[0112] Specifically include:

[0113] S51, calculating the lateral component of the maximum mooring force perpendicular to the front line of the wharf and the longitudinal component of the maximum mooring force parallel to the front line of the wharf according to the maximum mooring force;

[0114] The calculation formula is as follows:

[0115] ;

[0116] ;

[0117] Among them, N x Indicates the lateral component of the maximum mooring force perpendicular to the front line of the pier, N y It represents the longitudinal component of the maximum mooring force parallel to the front line of the pier, N represents the maximum mooring force, α represents the angle between the horizontal projection of the mooring cable and the front line of the pier, and β represents the angle between the mooring cable and the horizontal plane.

[0118] S52, calculating the lateral wave force on the target ship according to the lateral component of the maximum mooring force, the lateral component of the wind load, and the lateral component of the current load;

[0119] The calculation formula is as follows:

[0120] ;

[0121] Among them, F x ' represents the transverse wave force.

[0122] S53, calculating the longitudinal wave force on the target ship according to the longitudinal component of the maximum mooring force, the longitudinal component of the wind load, and the longitudinal component of the current load;

[0123] The calculation formula is as follows:

[0124] ;

[0125] Among them, F y ' represents the transverse wave force.

[0126] S6. Compare the estimated lateral force with the lateral wave force, and compare the estimated longitudinal force with the longitudinal wave force. If the difference between the estimated lateral force and the lateral wave force is greater than or equal to a preset threshold or the difference between the estimated longitudinal force and the longitudinal wave force is greater than or equal to the preset threshold, adjust the wave force comprehensive coefficient and return to S2. If the difference between the estimated lateral force and the lateral wave force is less than the preset threshold and the difference between the estimated longitudinal force and the longitudinal wave force is less than the preset threshold, calculate the wave load of the target ship according to the current wave force comprehensive coefficient and the estimation formula.

[0127] Specifically, compare F x and F x 'Whether the difference between them is greater than or equal to the preset threshold, F y and F y ' is greater than or equal to a preset threshold value, if so, the wave force comprehensive coefficient is adjusted. For example, the wave force comprehensive coefficient can be adjusted according to F x 'With F x The ratio of F is taken as the adjusted comprehensive coefficient of transverse wave force. y 'With F y The ratio of F is used as the adjusted longitudinal wave force comprehensive coefficient, and the estimated lateral force and estimated longitudinal force of the target ship are recalculated until F x and F x ' is less than the preset threshold, and F y and F y ' is less than the preset threshold, the comprehensive coefficient of the lateral wave force and the comprehensive coefficient of the longitudinal wave force at this time are substituted into the estimation formula to calculate the wave load of the target ship. The preset threshold is set according to the actual situation, and can be set to 5% for example.

[0128] The present invention collects test data on the motion model of LNG ships under the action of waves, establishes an empirical formula in combination with a comprehensive coefficient, and continuously corrects the comprehensive coefficient by comparing the calculated value with the actual test value, and finally obtains a calculation formula that can accurately calculate the wave load of the ship.

[0129] This method is based on the combination of measured data and theoretical analysis, and can quickly calculate the wave load of moored ships. It not only improves the accuracy of wave loads, but also can be widely applied to the analysis and calculation of wave loads of different LNG ships. It can statistically summarize the comprehensive coefficients of different ship types under different wave conditions. When the wave load needs to be calculated for the mooring design and operation of ships, it supplements the wave load calculation content that is currently missing in the "Port Engineering Load Code". In addition, the calculation process of this method is easy to understand and operate, does not require complex computing equipment and software, and is suitable for wide application in engineering practice.

[0130] The embodiment of the present invention provides a wave load calculation system for an LNG moored ship. Figure 3 is a schematic diagram of a wave load calculation system for LNG moored vessels provided by an embodiment of the present invention, see Figure 3 The system is used to implement the above-mentioned LNG moored ship wave load calculation method, and the system includes the following modules:

[0131] A data acquisition module, used to acquire ship parameters and wave parameters of the target ship;

[0132] The wave force estimation module is connected to the data acquisition module and is used to substitute the wave parameters, the ship parameters and the preset wave force comprehensive coefficient into the estimation formula to calculate the estimated lateral force and the estimated longitudinal force of the target ship under the action of the waves;

[0133] The mooring force calculation module is used to obtain the maximum mooring force on the target ship through model tests;

[0134] The wind load and water flow load calculation module is used to obtain hydrological conditions through the hydrological monitoring system and calculate the wind load and water flow load on the target ship according to the hydrological conditions;

[0135] A wave force calculation module is connected to the mooring force calculation module and the wind load and water flow load calculation module, and is used to calculate the transverse wave force and longitudinal wave force on the target ship according to the maximum mooring force, wind load and water flow load;

[0136] The formula correction module is connected to the wave force estimation module and the wave force calculation module, and is used to compare the estimated lateral force with the lateral wave force, and to compare the estimated longitudinal force with the longitudinal wave force, respectively. If the difference between the estimated lateral force and the lateral wave force is greater than or equal to a preset threshold or the difference between the estimated longitudinal force and the longitudinal wave force is greater than or equal to the preset threshold, the wave force comprehensive coefficient is adjusted, and the estimated lateral force and the estimated longitudinal force of the target ship under the action of waves are recalculated. If the difference between the estimated lateral force and the lateral wave force is less than the preset threshold and the difference between the estimated longitudinal force and the longitudinal wave force is less than the preset threshold, the wave load of the target ship is calculated according to the current wave force comprehensive coefficient and the estimation formula.

[0137] It should be noted that the terms used in the present invention are only for describing specific embodiments, rather than limiting the scope of the present application. As shown in the present specification, unless the context clearly indicates an exception, the words "one", "a", "a kind of" and / or "the" do not specifically refer to the singular, but may also include the plural. The terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method or device. In the absence of more restrictions, the elements defined by the sentence "include one..." do not exclude the presence of other identical elements in the process, method or device including the elements.

[0138] It should also be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. Unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", etc. should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0139] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention.

Claims

1. A method for calculating wave loads on LNG moored ships, characterized in that: The steps include: S1. Obtaining ship parameters and wave parameters of the target ship; S2, substituting the wave parameters, the ship parameters and the preset wave force comprehensive coefficient into the estimation formula to calculate the estimated lateral force and the estimated longitudinal force of the target ship under the action of the waves; S3. Obtain the maximum mooring force on the target ship through model tests; S4. Obtaining hydrological conditions through a hydrological monitoring system, and calculating wind loads and current loads on the target ship according to the hydrological conditions; S5. Calculating the transverse wave force and the longitudinal wave force on the target ship according to the maximum mooring force, wind load and water flow load; S6, respectively comparing the estimated lateral force with the lateral wave force, and comparing the estimated longitudinal force with the longitudinal wave force; if the difference between the estimated lateral force and the lateral wave force is greater than or equal to a preset threshold or the difference between the estimated longitudinal force and the longitudinal wave force is greater than or equal to the preset threshold, adjusting the wave force comprehensive coefficient, and returning to S2; if the difference between the estimated lateral force and the lateral wave force is less than the preset threshold and the difference between the estimated longitudinal force and the longitudinal wave force is less than the preset threshold, calculating the wave load of the target ship according to the current wave force comprehensive coefficient and the estimation formula.

2. A method for calculating wave loads on an LNG moored ship according to claim 1, characterized in that: In said S2, the preset wave force comprehensive coefficient includes a preset lateral wave force comprehensive coefficient and a preset longitudinal wave force comprehensive coefficient; Among them, the preset comprehensive coefficient of lateral wave force is 0.05; the preset comprehensive coefficient of longitudinal wave force is 0.

05.

3. A method for calculating wave loads on an LNG moored ship according to claim 2, characterized in that: In S2, the wave parameters, the ship parameters and the preset wave force comprehensive coefficient are substituted into the estimation formula to calculate the estimated lateral force and the estimated longitudinal force of the target ship under the action of the waves, specifically including: The estimation formula of the estimated lateral force of the target ship under the action of waves is as follows: ； Among them, F x represents the estimated lateral force, x represents the comprehensive coefficient of lateral wave force, H represents the incident wave height, θ represents the wave incident angle, L represents the length between the ship columns, D represents the ship draft, and a x represents the lateral magnification factor, γ represents the seawater density, and g represents the gravitational acceleration; The estimation formula of the estimated longitudinal force of the target ship under the action of waves is as follows: ； Among them, F y represents the estimated longitudinal force, y represents the comprehensive coefficient of longitudinal wave force, B represents the ship width, a y Represents the longitudinal magnification factor.

4. A method for calculating wave loads on an LNG moored ship according to claim 3, characterized in that: The calculation formula of the lateral magnification factor is as follows: ； Among them, T x represents the rolling period of the ship, T represents the wave period, μ x represents the lateral damping coefficient; The calculation formula of the longitudinal magnification factor is as follows: ； Among them, T y represents the pitch period of the ship, μ y represents the longitudinal damping coefficient.

5. The method for calculating wave loads on an LNG moored ship according to claim 1, characterized in that: In S4, the hydrological conditions are obtained through the hydrological monitoring system, and the wind load on the target ship is calculated according to the hydrological conditions. The calculation formula is as follows: ； ； Among them, F xw represents the lateral component of wind load, F yw A represents the longitudinal component of wind load. xw Indicates the lateral windward area above the water surface of the hull, A yw It represents the longitudinal windward area above the water surface of the hull, v x represents the lateral component of wind speed, v y represents the longitudinal component of wind speed, represents the wind pressure unevenness reduction coefficient, Indicates the correction factor for wind pressure height change.

6. A method for calculating wave loads on an LNG moored ship according to claim 5, characterized in that: In S4, the hydrological conditions are obtained through the hydrological monitoring system, and the water flow load on the target ship is calculated according to the hydrological conditions. The calculation formula is as follows: ； ； Among them, F TC represents the lateral component of the flow load, F LC represents the longitudinal component of the water flow load, C TC represents the lateral component coefficient of water flow force, ρ represents the density of water, V c Indicates the average flow velocity within the ship's draft depth, L BP represents the length between vertical lines of the ship, D' represents the average draft corresponding to the loading degree of the ship, θ c Indicates the angle between the water flow direction and the longitudinal axis of the ship, F LCP represents the longitudinal force component caused by form resistance, F LCf Represents the longitudinal component of force caused by frictional resistance.

7. A method for calculating wave loads on an LNG moored ship according to claim 6, characterized in that: In S5, the lateral wave force and the longitudinal wave force on the target ship are calculated according to the maximum mooring force, the wind load and the water flow load, which specifically includes: S51, calculating, according to the maximum mooring force, a lateral component of the maximum mooring force perpendicular to the front line of the wharf and a longitudinal component of the maximum mooring force parallel to the front line of the wharf; The calculation formula is as follows: ； ； Among them, N x Indicates the lateral component of the maximum mooring force perpendicular to the front line of the pier, N y represents the longitudinal component of the maximum mooring force parallel to the front line of the pier, N represents the maximum mooring force, α represents the angle between the horizontal projection of the mooring cable and the front line of the pier, and β represents the angle between the mooring cable and the horizontal plane; S52, calculating the lateral wave force on the target ship according to the lateral component of the maximum mooring force, the lateral component of the wind load, and the lateral component of the water flow load; The calculation formula is as follows: ； Among them, F x ' represents the transverse wave force; S53, calculating the longitudinal wave force on the target ship according to the longitudinal component of the maximum mooring force, the longitudinal component of the wind load, and the longitudinal component of the water flow load; The calculation formula is as follows: ； Among them, F y ' represents the transverse wave force.

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