Energy-saving effect evaluation method for wind-assisted propulsion of ship

Abstract

The invention belongs to the technical field of ship energy conservation and emission reduction, and provides an energy-saving effect evaluation method for wind-assisted propulsion of a ship. By establishing a unified wind-assisted propulsion ship energy-saving effect evaluation model suitable for each engineering stage, the wind-assisted propulsion ship energy-saving effect evaluation process is simplified, and the workload of repeatedly establishing the model in different engineering stages is reduced, so that the evaluation efficiency is improved; by defining a calculation model in a specific engineering stage, the accuracy and efficiency of energy-saving effect evaluation calculation of the wind-assisted propulsion ship can be ensured; according to the method for obtaining the relation between hydrodynamic force and aerodynamic force of a mechanical equilibrium equation / equation set of calculation models with different degrees of freedom and the sailing attitude and the effective thrust, unnecessary complexity and errors can be avoided, and meanwhile the energy-saving effect evaluation calculation speed of the wind-assisted propulsion ship is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of ship energy conservation and emission reduction, and in particular to a method for evaluating the energy conservation effect of a wind-assisted propulsion ship. Background Art

[0002] In order to promote energy conservation and emission reduction during the operation of ships, the use of wind-assisted propulsion devices is actively promoted. The most significant role of wind-assisted propulsion devices is to improve energy efficiency and environmental protection. By capturing and utilizing natural wind power, wind propellers provide part of the power for ships, thereby reducing dependence on traditional fuels. This not only reduces operating costs, but also reduces greenhouse gas emissions, which is environmentally friendly.

[0003] The energy-saving effect evaluation model of wind-assisted propulsion ships is used to evaluate the energy-saving effect of ships equipped with wind-assisted propulsion devices (such as Flettnor rotors, wing sails, etc.). The energy-saving effect evaluation model of wind-assisted propulsion ships includes the ship mechanical equilibrium equation / equation group, and the calculation / test method of the relationship between the hydrodynamic force and aerodynamic force and the navigation attitude (rudder angle, drift angle, heel angle) and effective thrust in the equation / equation group. The mechanical equilibrium equation group can be single-degree-of-freedom, two-degree-of-freedom, three-degree-of-freedom or four-degree-of-freedom (the fifth and sixth degrees of freedom, i.e., vertical force balance and longitudinal moment balance, are rarely considered), depending on the different requirements for accuracy at different engineering stages. The method for obtaining the relationship between the hydrodynamic force and aerodynamic force and the navigation attitude and effective thrust can be an estimation method based on empirical formulas, a numerical calculation method, or a constrained model test method, which also depends on the different requirements for accuracy at different engineering stages.

[0004] In the existing schemes, these methods have not been systematically summarized and organized, so there is a lack of a unified and applicable method for evaluating the energy-saving effects of wind-assisted propulsion ships in various engineering stages. It is not clear what number of degrees of freedom the mechanical equilibrium equation or set of equations should be used in a specific engineering stage, and what method should be used to obtain the relationship between the hydrodynamic and aerodynamic forces and the navigation attitude and effective thrust corresponding to the mechanical equilibrium equation or set of equations with different degrees of freedom. Summary of the invention

[0005] In view of the problem that there is a lack of a unified energy-saving effect evaluation method for wind-assisted propulsion ships applicable to various engineering stages in the existing technology, a method for evaluating the energy-saving effect of wind-assisted propulsion ships is proposed, and a unified energy-saving effect evaluation model for wind-assisted propulsion ships applicable to various engineering stages is established. The calculation model corresponding to the number of degrees of freedom in a specific engineering stage and the method for obtaining the relationship between the hydrodynamic and aerodynamic forces and the navigation attitude and effective thrust to be adopted in the mechanical equilibrium equation or equation group in the calculation model are clarified. The relationship between evaluation accuracy and calculation efficiency is well balanced, and different evaluation standards may need to be emphasized in different engineering stages to meet diverse needs.

[0006] The specific method is as follows:

[0007] A method for evaluating energy-saving effect of a wind-assisted propulsion ship, comprising:

[0008] S1: The staff inputs the current engineering stage; the number of degrees of freedom required for the corresponding ship motion calculation model is matched according to the engineering stage; the higher the number of degrees of freedom, the more forces need to be considered in the current engineering stage, and the higher the calculation accuracy;

[0009] S2: Determine the calculation model corresponding to the current engineering stage according to the number of degrees of freedom in S1; the calculation model includes: a mechanical equilibrium equation or a set of equations;

[0010] S3: According to the number of degrees of freedom in S1 and the calculation model in S2, a method for obtaining the relationship between the hydrodynamic force and the aerodynamic force and the navigation attitude and the effective thrust is selected; according to the method for obtaining, specific values ​​of the relationship between the hydrodynamic force and the aerodynamic force and the navigation attitude and the effective thrust are obtained; the specific values ​​are substituted into the calculation model in S2 for solving, and the navigation attitude and the effective thrust are obtained; after the single degree of freedom solution, only the effective thrust is obtained;

[0011] S4: Calculate the power saving rate of the wind-assisted propulsion device according to the effective thrust of S3;

[0012] S5: Repeat S2-S4 to calculate the power saving rate of the wind-assisted propulsion device at different wind speeds and wind directions;

[0013] S6: Calculate the average power savings of the wind-assisted propulsion device at different wind speeds and wind directions using the global average route wind speed and wind direction probability matrix and the S5 power savings rate.

[0014] Preferably, the engineering stages are divided into five levels according to the energy-saving effect evaluation accuracy, corresponding to five engineering stages, including:

[0015] Level 1: corresponds to single degree of freedom, which belongs to the market research stage; it evaluates the output power of a single wind-assisted propulsion device independent of the ship and the route; the single degree of freedom only focuses on the force acting on the ship in a specific direction;

[0016] Level 2: corresponds to two degrees of freedom, belonging to the early conceptual design stage; evaluates the energy-saving effect of installing a wind-assisted propulsion device on a given ship; the two degrees of freedom mentioned above focus on the forces acting on the ship during planar motion, and consider the influence of the rudder angle on the ship's motion;

[0017] Level 3: corresponds to three or four degrees of freedom, belonging to the early case analysis stage; carefully evaluate the energy-saving effect of wind-assisted propulsion devices; use low or medium fidelity methods to calculate hydrodynamics and aerodynamics; the three degrees of freedom focus on the forces acting on the ship when it is in planar motion, considering the effects of rudder angle and drift angle on the ship's motion; the four degrees of freedom focus on the operating forces of the ship in three-dimensional space, considering the effects of rudder angle, drift angle and heel angle on the ship's motion;

[0018] Level 4: corresponds to three or four degrees of freedom, belonging to the case analysis and performance prediction stage; the energy saving potential of wind-assisted propulsion ships is evaluated based on the standard that a performance contract can be established; high-fidelity methods must be used to calculate hydrodynamics and aerodynamics;

[0019] Level 5: corresponds to four degrees of freedom and belongs to the later stage of case analysis and performance evaluation. It comprehensively evaluates the energy-saving effects of multi-route ships, typical wind-assisted propulsion ships, and ships with advanced hybrid propulsion systems. At the same time, it can calculate the energy-saving effects of wind-assisted propulsion devices under different wind speed profiles and different routes.

[0020] Preferably, the mechanical equilibrium equation or set of equations calculated according to the number of degrees of freedom is:

[0021] (I) The mechanical equilibrium equation in the calculation model corresponding to a single degree of freedom is shown in formula (1):

[0022] ∑F X =X CW +X AW +X W +X S +X R (T E )+T E =0 (1)

[0023] Among them, X CW represents hydrostatic resistance; X AW Indicates wave resistance increase; X W It represents the component of the windward force on the hull and superstructure above the waterline along the X-axis direction; S Indicates the thrust generated by the wind-assisted propulsion device; XR represents the component of the rudder force along the X-axis direction; T E Indicates effective thrust;

[0024] (ii) The mechanical equilibrium equations in the calculation model corresponding to two degrees of freedom are shown in formulas (2)-(3):

[0025] ∑F X =X CW +X AW +X W +X S +X R (δ,T E )+T E =0 (2)

[0026] ∑M Z =Y R (δ,T E )L PP +Y S x S -X S y S +Y W x W -X W y W =0 (3)

[0027] Where, δ represents the rudder angle; L PP Indicates the length between vertical lines of the ship; Y R Indicates the component of the rudder force along the Y axis; S The lateral force generated by the wind-assisted propulsion device is the force along the Y axis; W The Y-axis component of the windward force on the hull and superstructure above the waterline; S and S The x and y coordinates of the points where the thrust and lateral force generated by the wind-assisted propulsion device are applied; W and W It indicates the horizontal and vertical (x, y) coordinates of the points where the windward force acts on the hull and superstructure above the waterline;

[0028] (III) The mechanical equilibrium equations in the calculation model corresponding to the three degrees of freedom are shown in formulas (4)-(6):

[0029] ∑F X =X CW +X AW +X H (β)+X W (β)+X S (β)+X R (δ,β,T E )+T E =0 (4)

[0030] ∑F Y =Y H (β)+Y R (δ,β,T E )+Y S (β)+Y W (β)=0 (5)

[0031]

[0032] Where β represents the drift angle; X H and Y H They represent the additional resistance of drift angle, i.e., the component force along the X-axis direction, and the lateral force, i.e., the component force along the Y-axis direction; CLR represents the distance from the additional resistance of drift angle and the point of action of lateral force to the bow;

[0033] (IV) The mechanical equilibrium equations in the calculation model corresponding to the four degrees of freedom are shown in formulas (7)-(10):

[0034]

[0035] in, represents the heel angle; GM represents high static stability; Δ represents displacement; g represents gravitational acceleration; z H Indicates the z coordinate of the point where the drift angle additional resistance and lateral force act; W The z represents the z coordinate of the point above the waterline where the windward force on the hull and superstructure acts; S The z coordinate represents the point of action of the thrust and lateral force generated by the wind-assisted propulsion device; R Indicates the z coordinate of the point where the rudder force acts.

[0036] Preferably, before constructing the corresponding calculation model according to the number of degrees of freedom, it is necessary to establish a wind-assisted propulsion coordinate system; the coordinate origin of the coordinate system is at the bow, and the height is at the keel; the X-axis points to the stern, the Y-axis points to the starboard, and the Z-axis is vertically upward, and the three constitute a Cartesian rectangular coordinate system.

[0037] Preferably, before constructing the corresponding calculation model according to the number of degrees of freedom, the directions of the forces and moments on the ship need to be determined; the directions of the forces and moments are positive if they are consistent with the coordinate axis, and negative if they are opposite; the positive and negative definitions of the motion of the ship (including the appendage) and the definition of the wind direction angle are as follows:

[0038] Drift angle: refers to the angle between heading and heading, with counterclockwise being positive;

[0039] Rudder angle: indicates right rudder is positive;

[0040] Heel angle: indicates that the left tilt is positive;

[0041] Wind direction angle: It indicates the angle between the positive direction of the X-axis and the wind direction, with counterclockwise being positive.

[0042] Preferably, the method for obtaining effective thrust is:

[0043] S31: Determine the relationship between the required hydrodynamic force and aerodynamic force and the navigation attitude and effective thrust according to the mechanical equilibrium equation or equation group in the S2 calculation model;

[0044] S32: Determine the method for obtaining the relationship between the hydrodynamic force and aerodynamic force required by S31 and the navigation attitude and effective thrust according to the number of degrees of freedom of S1; the obtaining method refers to the specific means or ways to obtain the relationship between the hydrodynamic force and aerodynamic force and the navigation attitude and effective thrust, and the obtaining method includes: an estimation method based on an empirical formula, a numerical calculation method, i.e., 3D CFD, and a constrained model test method;

[0045] S33: using the acquisition method of S32 to obtain specific values ​​of the relationship between the hydrodynamic force and aerodynamic force required by S31 and the navigation attitude and effective thrust;

[0046] S34: Substitute the specific value of S33 into the mechanical equilibrium equation or equation group in the S2 calculation model to calculate the effective thrust.

[0047] Preferably, the relationship between the aerodynamic force and the sailing attitude and effective thrust includes: the thrust and lateral force of the wind-assisted propulsion device, the power required for the operation of the wind-assisted propulsion device, the aerodynamic interaction between the wind-assisted propulsion devices, the aerodynamic interaction between the wind-assisted propulsion device and the superstructure, and the aerodynamic force of the superstructure; the relationship between the hydrodynamic force and the sailing attitude and effective thrust includes: still water resistance, wave resistance increase, propeller open water performance, propeller propulsion efficiency, rudder angle additional resistance and lateral force, and drift angle additional resistance and lateral force.

[0048] Preferably, the specific expression of the power saving rate of the wind-assisted propulsion device is as follows:

[0049] According to the effective thrust T E Calculate the effective power P E , as shown in formula (11):

[0050] P E =T E V S (11)

[0051] Among them, V S Indicates the speed of the ship;

[0052] According to formula (12), the main engine power P when using the wind-assisted thrust device is obtained: S_total :

[0053]

[0054] Among them, η D represents propeller propulsion efficiency; η S Indicates the host transmission efficiency; P S Indicates the power required for navigation; P S_rotor Indicates the power required for the operation of wind-assisted propulsion devices;

[0055] The power saving rate of the wind-assisted propulsion device is calculated according to formula (13):

[0056]

[0057] Among them, P S_total,w / oSail Indicates the main engine power required without wind-assisted thrust device.

[0058] Preferably, the expression for the average power saving of the wind-assisted propulsion device at different wind speeds and wind directions is:

[0059]

[0060] Among them, TWS&TWA_AvgR savings Indicates the average power saving rate of wind speed and direction; w TWA Indicates the probability of different wind directions; w TWS Indicates the probability of different wind speeds.

[0061] Beneficial effects:

[0062] The present invention proposes a method for evaluating the energy-saving effect of wind-assisted propulsion ships, establishes a unified model for evaluating the energy-saving effect of wind-assisted propulsion ships applicable to various engineering stages, clarifies the number of degrees of freedom of the calculation model required to be adopted in a specific engineering stage, and the method for obtaining the relationship between the hydrodynamic force and aerodynamic force and the navigation attitude and effective thrust corresponding to the mechanical equilibrium equation / equation group of the calculation model with different degrees of freedom, and better balances the relationship between evaluation accuracy and calculation efficiency. Specifically:

[0063] By establishing a unified energy-saving effect evaluation model for wind-assisted propulsion ships applicable to each engineering stage, which covers calculation models corresponding to single degree of freedom, two degrees of freedom, three degrees of freedom and four degrees of freedom, the energy-saving effect evaluation process of wind-assisted propulsion ships can be simplified. By establishing an evaluation model, not only can the workload of repeatedly establishing models at different engineering stages be effectively reduced, and the evaluation efficiency be improved; at the same time, by standardizing the evaluation methods at different engineering stages, the evaluation of the energy-saving effect of wind-assisted propulsion ships can be ensured to be both fast and accurate, which is convenient for comparison and analysis between stages.

[0064] By clarifying the calculation models required at specific engineering stages, the accuracy and efficiency of the energy-saving effect evaluation calculation of wind-assisted propulsion ships can be ensured. By clarifying the method of obtaining the relationship between the hydrodynamic and aerodynamic forces and the navigation attitude and effective thrust of the mechanical equilibrium equations / equation groups of calculation models with different degrees of freedom, it not only helps to avoid unnecessary complexity and potential errors, but also speeds up the evaluation of the energy-saving effect of wind-assisted propulsion ships. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 The present invention is a flow chart of a method for evaluating energy saving effect of wind-assisted propulsion ship.

[0066] Figure 2 Coordinate system for wind-assisted propulsion ships. DETAILED DESCRIPTION

[0067] A method for evaluating energy-saving effect of a wind-assisted propulsion ship, comprising:

[0068] S1: The staff inputs the current engineering stage; the number of degrees of freedom required for the corresponding ship motion calculation model is matched according to the engineering stage; the higher the number of degrees of freedom, the more forces need to be considered in the current engineering stage, and the higher the calculation accuracy;

[0069] S2: Determine the calculation model corresponding to the current engineering stage according to the number of degrees of freedom in S1; the calculation model includes: a mechanical equilibrium equation or a set of equations;

[0070] S3: According to the number of degrees of freedom in S1 and the calculation model in S2, a method for obtaining the relationship between the hydrodynamic force and the aerodynamic force and the navigation attitude and the effective thrust is selected; according to the method for obtaining, specific values ​​of the relationship between the hydrodynamic force and the aerodynamic force and the navigation attitude and the effective thrust are obtained; the specific values ​​are substituted into the calculation model in S2 for solving, and the navigation attitude and the effective thrust are obtained; after the single degree of freedom solution, only the effective thrust is obtained;

[0071] S4: Calculate the power saving rate of the wind-assisted propulsion device according to the effective thrust of S3;

[0072] S5: Repeat S2-S4 to calculate the power saving rate of the wind-assisted propulsion device at different wind speeds and wind directions;

[0073] S6: Calculate the average power savings of the wind-assisted propulsion device at different wind speeds and wind directions using the global average route wind speed and wind direction probability matrix and the S5 power savings rate.

[0074] The specific method is:

[0075] Establish a unified energy-saving effect evaluation model for wind-assisted propulsion ships applicable to all engineering stages, clarify the number of degrees of freedom of the mechanical equilibrium equation / equation group required in a specific engineering stage, and the method of obtaining the relationship between the hydrodynamic and aerodynamic forces and the navigation attitude and effective thrust corresponding to the mechanical equilibrium equation / equation group with different degrees of freedom.

[0076] The energy-saving effect evaluation accuracy is divided into five levels, corresponding to five engineering stages. The types of mechanical equilibrium equations / equation groups to be used in different engineering stages are shown in Table 1.

[0077] Table 1 - Types of mechanical equilibrium equations / equation groups to be used in different engineering stages

[0078]

[0079]

[0080] In Table 1, the mechanical equilibrium equations / equation groups with different degrees of freedom are as follows. When establishing mechanical equilibrium equations / equation groups, pay attention to the positive and negative signs. Strictly follow Figure 2 The defined positive and negative signs are used to substitute the specific numerical values ​​of the relationship between the calculated hydrodynamic and aerodynamic forces acting on the wind-assisted propulsion ship and the navigation attitude and effective thrust into the mechanical equilibrium equation / equation group.

[0081] Establish a wind-assisted propulsion ship coordinate system. The origin of the coordinate is at the bow, and the height is at the keel. The X-axis points to the stern, the Y-axis points to the starboard, and the Z-axis is vertically upward. The three form a Cartesian rectangular coordinate system, such as Figure 1 shown.

[0082] The direction of the force and moment on the ship is positive if it is consistent with the coordinate axis, and negative if it is opposite. The positive and negative definitions of the ship (including appendages) motion and the definition of the wind direction angle are as follows:

[0083] Drift angle - the angle between heading and heading, counterclockwise is positive;

[0084] Rudder angle - right rudder is positive;

[0085] Heel angle - left heel is positive;

[0086] Wind direction angle - the angle between the positive X-axis and the wind direction, with counterclockwise being positive.

[0087] (I) The mechanical equilibrium equation in the calculation model corresponding to a single degree of freedom is as follows:

[0088] ∑F X =X CW +X AW +X W +X S +X R(T E )+T E =0 (1)

[0089] Among them, X CW represents hydrostatic resistance; X AW Indicates wave resistance increase; X W and Y W It represents the component of the windward force on the hull and superstructure above the waterline along the X-axis direction; S Indicates the thrust generated by the wind-assisted propulsion device; X R represents the component of the rudder force along the X-axis direction; T E Indicates effective thrust;

[0090] (II) The mechanical equilibrium equations in the calculation model corresponding to two degrees of freedom are as follows:

[0091] ∑F X =X CW +X AW +X W +X S +X R (δ,T E )+T E =0 (2)

[0092] ∑M Z =Y R (δ,T E )L PP +Y S x S -X S y S +Y W x W -X W y W =0 (3)

[0093] Where, δ represents the rudder angle; L PP Indicates the length between vertical lines of the ship; Y R Indicates the component of the rudder force along the Y axis; S The lateral force generated by the wind-assisted propulsion device is the force along the Y axis; W The Y-axis component of the windward force on the hull and superstructure above the waterline; S and S The x and y coordinates of the points where the thrust and lateral force generated by the wind-assisted propulsion device are applied; W and W It indicates the horizontal and vertical (x, y) coordinates of the points where the windward force acts on the hull and superstructure above the waterline;

[0094] (III) The mechanical equilibrium equations in the calculation model corresponding to the three degrees of freedom are as follows:

[0095] ∑F X =X CW +X AW +X H (β)+X W (β)+X S (β)+X R (δ,β,T E )+T E =0 (4)

[0096] ∑F Y =Y H (β)+Y R (δ,β,T E )+Y S (β)+Y W (β)=0 (5)

[0097]

[0098] Where β represents the drift angle; X H and Y H It indicates the additional resistance of drift angle, i.e. the component force along the X-axis direction, and the lateral force, i.e. the component force along the Y-axis direction; CLR indicates the distance from the additional resistance of drift angle and the point of action of lateral force to the bow;

[0099] (IV) The mechanical equilibrium equations in the calculation model corresponding to the four degrees of freedom are shown in equations (7)-(10):

[0100]

[0101] in, represents the heel angle; GM represents high static stability; Δ represents displacement; g represents gravitational acceleration; z H Indicates the z coordinate of the point where the drift angle additional resistance and lateral force act; W The z represents the z coordinate of the point above the waterline where the windward force on the hull and superstructure acts; S The z coordinate represents the point of action of the thrust and lateral force generated by the wind-assisted propulsion device; R Indicates the z coordinate of the point where the rudder force acts.

[0102] In mechanical equilibrium equations or systems of equations, the unknown quantities are highly coupled and have implicit relationships with each other, so numerical algorithms must be used to write calculation programs to solve them. When selecting numerical methods, it is recommended to use numerical methods that do not require derivatives to deal with systems of equations with complex expressions that may contain spatially non-differentiable terms.

[0103] The mechanical equilibrium equations / equation groups with different degrees of freedom and the corresponding methods for obtaining the relationship between the hydrodynamic force and aerodynamic force and the navigation attitude and effective thrust are shown in Table 2.

[0104] Table 2 - Methods for obtaining the relationship between hydrodynamics and aerodynamics and navigation attitude and effective thrust corresponding to different mechanical equilibrium equations / equation groups

[0105]

[0106]

[0107]

[0108] According to the effective thrust T E Calculate the effective power P E , as shown in formula (11):

[0109] P E =T E V S (11)

[0110] Among them, V S Indicates the speed of the ship;

[0111] According to formula (12), the main engine power P when using the wind-assisted thrust device is obtained: S_total :

[0112]

[0113] Among them, η D represents propeller propulsion efficiency; η S Indicates the host transmission efficiency; P S Indicates the power required for navigation; P S_rotor Indicates the power required for the operation of wind-assisted propulsion devices.

[0114] The power saving rate of the wind-assisted propulsion device is calculated according to formula (13):

[0115]

[0116] Among them, P S_total,w / oSail Indicates the main engine power required without wind-assisted thrust device.

[0117] The power saving and energy-saving effect under different wind speeds and wind directions are calculated, and the global average route wind speed and wind direction probability matrix (Global Wind Probability Matrix) recommended by IMO is applied to obtain the expression of the average power saving of the wind-assisted propulsion device under different wind speeds and wind directions:

[0118]

[0119] Among them: TWS&TWA_AvgR savings It is the average power saving rate of wind speed and direction; w TWA That is to say, the probability of different wind directions; w TWS That is to say, the probability of different wind speeds, w TWS and w TWA All are taken from the global average route wind speed and direction probability matrix in "IMO-MEPC.1-Circ.896-2021 Guidance On Treatment Of Innovative Energy Efficiency Technologies for Calculation and Verification of the Attained EEDI and EEXI".

[0120] Finally, it should be noted that the above is only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred arrangement scheme, a person skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for evaluating energy-saving effects of wind-assisted propulsion ships, characterized in that: include: S1: The staff inputs the current project stage; The number of degrees of freedom required for matching the corresponding ship motion calculation model according to the engineering stage; the higher the number of degrees of freedom, the more forces need to be considered in the current engineering stage, and the higher the calculation accuracy; S2: Determine the calculation model corresponding to the current engineering stage according to the number of degrees of freedom in S1; the calculation model includes: a mechanical equilibrium equation or a set of equations; S3: According to the number of degrees of freedom in S1 and the calculation model in S2, a method for obtaining the relationship between the hydrodynamic force and the aerodynamic force and the navigation attitude and the effective thrust is selected; according to the method for obtaining, specific values ​​of the relationship between the hydrodynamic force and the aerodynamic force and the navigation attitude and the effective thrust are obtained; the specific values ​​are substituted into the calculation model in S2 for solving, and the navigation attitude and the effective thrust are obtained; after the single degree of freedom solution, only the effective thrust is obtained; S4: Calculate the power saving rate of the wind-assisted propulsion device according to the effective thrust of S3; S5: Repeat S2-S4 to calculate the power saving rate of the wind-assisted propulsion device at different wind speeds and wind directions; S6: Calculate the average power savings of the wind-assisted propulsion device at different wind speeds and wind directions using the global average route wind speed and wind direction probability matrix and the S5 power savings rate.

2. A method for evaluating energy-saving effects of wind-assisted propulsion ships according to claim 1, characterized in that: The engineering stages are divided into five levels according to the accuracy of energy-saving effect assessment, corresponding to five engineering stages, including: Level 1: corresponds to single degree of freedom, which belongs to the market research stage; it evaluates the output power of a single wind-assisted propulsion device independent of the ship and the route; the single degree of freedom only focuses on the force acting on the ship in a specific direction; Level 2: corresponds to two degrees of freedom, belonging to the early conceptual design stage; evaluates the energy-saving effect of installing a wind-assisted propulsion device on a given ship; the two degrees of freedom mentioned above focus on the forces acting on the ship during planar motion, and consider the influence of the rudder angle on the ship's motion; Level 3: corresponds to three or four degrees of freedom, belonging to the early case analysis stage; carefully evaluate the energy-saving effect of wind-assisted propulsion devices; use low or medium fidelity methods to calculate hydrodynamics and aerodynamics; the three degrees of freedom focus on the forces acting on the ship during planar motion, considering the effects of rudder angle and drift angle on the ship's motion; the four degrees of freedom focus on the operating forces of the ship in three-dimensional space, considering the effects of rudder angle, drift angle and heel angle on the ship's motion; Level 4: corresponds to three or four degrees of freedom, belonging to the case analysis and performance prediction stage; the energy saving potential of wind-assisted propulsion ships is evaluated based on the standard that a performance contract can be established; high-fidelity methods must be used to calculate hydrodynamics and aerodynamics; Level 5: corresponds to four degrees of freedom and belongs to the later stage of case analysis and performance evaluation. It comprehensively evaluates the energy-saving effects of multi-route ships, typical wind-assisted propulsion ships, and ships with advanced hybrid propulsion systems. At the same time, it can calculate the energy-saving effects of wind-assisted propulsion devices under different wind speed profiles and different routes.

3. A method for evaluating energy-saving effects of wind-assisted propulsion ships according to claim 1, characterized in that: The mechanical equilibrium equation or set of equations corresponding to the calculation of the number of degrees of freedom is: (I) The mechanical equilibrium equation in the calculation model corresponding to a single degree of freedom is shown in formula (1): ∑F X =X CW +X AW +X W +X S +X R (T E )+T E =0 (1) Among them, X CW represents hydrostatic resistance; X AW Indicates wave resistance increase; X W It represents the component of the windward force on the hull and superstructure above the waterline along the X-axis direction; S Indicates the thrust generated by the wind-assisted propulsion device; X R represents the component of the rudder force along the X-axis direction; T E Indicates effective thrust; (ii) The mechanical equilibrium equations in the calculation model corresponding to two degrees of freedom are shown in formulas (2)-(3): ∑F X =X CW +X AW +X W +X S +X R (δ,T E )+T E =0 (2) ∑M Z =And R (δ,T E )L PP +Y S x S -X S and S +Y W x W -X W and W =0 (3) Where, δ represents the rudder angle; L PP Indicates the length between vertical lines of the ship; Y R Indicates the component of the rudder force along the Y axis; S The lateral force generated by the wind-assisted propulsion device is the force along the Y axis; W The Y-axis component of the windward force on the hull and superstructure above the waterline; S and S The x and y coordinates of the points where the thrust and lateral force generated by the wind-assisted propulsion device are applied; W and W It indicates the horizontal and vertical (x, y) coordinates of the points where the windward force acts on the hull and superstructure above the waterline; (III) The mechanical equilibrium equations in the calculation model corresponding to the three degrees of freedom are shown in formulas (4)-(6): ∑F X =X CW +X AW +X H (b)+X W (b)+X S (b)+X R (d,b,T E )+T E =0 (4) ∑F Y =Y H (b)+Y R (d,b,T E )+Y S (b)+Y W (b)=0 (5) ∑M Z =Y H (β)CLR+Y R (δ,β,T E )L PP +Y S (β)x S -X S (β)y S (6) +Y W (b)x W -X W (b)y W =0 Where β represents the drift angle; X H and Y H They represent the additional resistance of drift angle, i.e., the component force along the X-axis direction, and the lateral force, i.e., the component force along the Y-axis direction; CLR represents the distance from the additional resistance of drift angle and the point of action of lateral force to the bow; (IV) The mechanical equilibrium equations in the calculation model corresponding to the four degrees of freedom are shown in formulas (7)-(10): in, represents the heel angle; GM represents high static stability; Δ represents displacement; g represents gravitational acceleration; z H Indicates the z coordinate of the point where the drift angle additional resistance and lateral force act; W The z represents the z coordinate of the point above the waterline where the windward force on the hull and superstructure acts; S The z coordinate represents the point of action of the thrust and lateral force generated by the wind-assisted propulsion device; R Indicates the z coordinate of the point where the rudder force acts.

4. A method for evaluating energy-saving effects of wind-assisted propulsion ships according to claim 3, characterized in that: Before constructing the corresponding calculation model according to the number of degrees of freedom, it is necessary to establish a wind-assisted propulsion coordinate system; the coordinate origin of the coordinate system is at the bow, and the height is at the keel; the X-axis points to the stern, the Y-axis points to the starboard, and the Z-axis is vertically upward, and the three constitute a Cartesian rectangular coordinate system.

5. A method for evaluating energy-saving effects of wind-assisted propulsion ships according to claim 3, characterized in that: Before constructing the corresponding calculation model according to the number of degrees of freedom, the direction of the force and moment on the ship must be determined; the direction of the force and moment is positive if it is consistent with the coordinate axis, and negative if it is opposite; the positive and negative definitions of the ship (including the appendage) motion and the definition of the wind direction angle are as follows: Drift angle: refers to the angle between heading and heading, with counterclockwise being positive; Rudder angle: indicates right rudder is positive; Heel angle: indicates that the left heel is positive; Wind direction angle: It indicates the angle between the positive direction of the X-axis and the wind direction, with counterclockwise being positive.

6. A method for evaluating energy-saving effects of wind-assisted propulsion ships according to claim 1, characterized in that: The method for obtaining effective thrust: S31: Determine the relationship between the required hydrodynamic force and aerodynamic force and the navigation attitude and effective thrust according to the mechanical equilibrium equation or equation group in the S2 calculation model; S32: Determine the method for obtaining the relationship between the hydrodynamic force and aerodynamic force required by S31 and the navigation attitude and effective thrust according to the number of degrees of freedom of S1; the obtaining method refers to the specific means or ways to obtain the relationship between the hydrodynamic force and aerodynamic force and the navigation attitude and effective thrust, and the obtaining method includes: an estimation method based on an empirical formula, a numerical calculation method, i.e., 3D CFD, and a constrained model test method; S33: using the acquisition method of S32 to obtain specific values ​​of the relationship between the hydrodynamic force and aerodynamic force required by S31 and the navigation attitude and effective thrust; S34: Substitute the specific value of S33 into the mechanical equilibrium equation or equation group in the S2 calculation model to calculate the effective thrust.

7. A method for evaluating energy-saving effects of wind-assisted propulsion ships according to claim 6, characterized in that: The relationship between the aerodynamic force and the navigation attitude and effective thrust includes: the thrust and lateral force of the wind-assisted propulsion device, the power required for the operation of the wind-assisted propulsion device, the aerodynamic interaction between the wind-assisted propulsion devices, the aerodynamic interaction between the wind-assisted propulsion device and the superstructure, and the aerodynamic force of the superstructure; the relationship between the hydrodynamic force and the navigation attitude and effective thrust includes: still water resistance, wave resistance increase, propeller open water performance, propeller propulsion efficiency, rudder angle additional resistance and lateral force, and drift angle additional resistance and lateral force.

8. A method for evaluating energy-saving effects of wind-assisted propulsion ships according to claim 1, characterized in that: The specific expression of the power saving rate of the wind-assisted propulsion device is as follows: According to the effective thrust T E Calculate the effective power P E , as shown in formula (11): P E =T E V S (11) Among them, V S Indicates the speed of the ship; According to formula (12), the main engine power P when using the wind-assisted thrust device is obtained: S_total : Among them, η D represents propeller propulsion efficiency; η S Indicates the host transmission efficiency; P S Indicates the power required for navigation; P S_rotor Indicates the power required for the operation of wind-assisted propulsion devices; The power saving rate of the wind-assisted propulsion device is calculated according to formula (13): Among them, P S_total,w / oSail Indicates the main engine power required without wind-assisted thrust device.

9. A method for evaluating energy-saving effects of wind-assisted propulsion ships according to claim 1, characterized in that: The expression for the average power saving of the wind-assisted propulsion device at different wind speeds and wind directions is: Among them, TWS&TWA_AvgR savings Indicates the average power saving rate of wind speed and direction; w TWA Indicates the probability of different wind directions; w TWS Indicates the probability of different wind speeds.

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