A single sail layout optimization method for wind-assisted propulsion ships

Abstract

The present invention relates to the technical field of wind-assisted propulsion ships, and proposes a method for optimizing the layout of a single sail of a wind-assisted propulsion ship. The method uses a combination of an artificial neural network and a multi-objective genetic algorithm, that is, an artificial neural network is used to construct a proxy surface model of the relationship between the saving rate of the main engine power and the layout of a single sail, and a proxy surface model of the relationship between the propulsion efficiency of the main propulsion device and the layout of a single sail; then, using the proxy surface as the fitness, a multi-objective genetic algorithm is used to perform multi-objective optimization on the layout of a single sail, and obtain the optimal spatial layout (i.e., position) of a single sail in a given deck space for a given ship, a given single sail, and a given speed. The present invention can achieve multi-objective optimization, that is, taking into account both the maximization of the saving rate of the main engine power and the maximization of the propulsion efficiency of the main propulsion device; at the same time, it has high efficiency and can be used for feasibility analysis and preliminary design of energy efficiency improvement of wind-assisted propulsion ships.

Description

Technical Field

[0001] The present invention relates to the technical field of wind-assisted propulsion ships, and in particular to a method for optimizing the layout of a single sail of a wind-assisted propulsion ship. Background Art

[0002] Wind-assisted propulsion systems provide thrust to ships in favorable winds, reducing effective power while maintaining constant speed, thereby reducing the power required by the main engine. Given a given ship, a single sail, and a given speed, within a given deck space, optimizing the individual sail layout—that is, determining the position of the sails to maximize main engine power savings while maximizing the propulsion efficiency of the main propulsion system—has become a key concern in the design of wind-assisted ships.

[0003] Existing optimization schemes for the layout of individual sails on wind-assisted propulsion ships mainly use the enumeration method, that is, continuously changing the position of a single sail in the available deck space in small steps, obtaining the law of change of the main engine power saving rate with the position of a single sail, and finding the optimal position of a single sail.

[0004] The disadvantages of the existing solution are:

[0005] (1) It is only applicable to single-objective optimization, not multi-objective optimization;

[0006] (2) Under each layout of a single sail, the power saving rate of the main engine and the propulsion efficiency of the main propulsion device need to be obtained by solving the energy-saving effect evaluation model of the wind-assisted propulsion ship. The energy-saving effect evaluation model contains a four-degree-of-freedom mechanical equilibrium equation group, as well as the relationship between the hydrodynamic force / aerodynamic force on the ship and the navigation attitude (rudder angle, drift angle, roll angle) and effective thrust in the equation group. The relationship between the hydrodynamic force and aerodynamic force and the navigation attitude and effective thrust can be obtained through empirical / semi-empirical formulas, or by three-dimensional CFD calculations or model tests. When the latter is adopted, if the existing scheme, that is, the enumeration method, is used for optimization, the efficiency is low and it is not suitable for the feasibility analysis and preliminary design of energy efficiency improvement of wind-assisted propulsion ships. Summary of the Invention

[0007] In order to solve the technical problem that the existing technology cannot achieve multi-objective optimization and is inefficient, and is therefore not suitable for the feasibility analysis and preliminary design of energy efficiency improvement of wind-assisted propulsion ships, the present invention proposes a method for optimizing the layout of a single sail of a wind-assisted propulsion ship, which uses a method combining an artificial neural network with a multi-objective genetic algorithm to obtain the optimal spatial layout, i.e., the position, of a single sail in a given deck space.

[0008] The specific plan is as follows:

[0009] A single sail layout optimization method for a wind-assisted propulsion ship.

[0010] S1, parameter setting: given ship type, single sail, speed, and sea conditions as parameters:

[0011] S2, solve the performance evaluation model of wind-assisted propulsion ship: substitute the parameters in S1 into the performance evaluation model of wind-assisted propulsion ship to obtain the main engine power saving rate and the propulsion efficiency of the main propulsion device;

[0012] S3, solve the model by changing wind speed and direction: calculate the main engine power saving rate and the propulsion efficiency of the main propulsion device at different wind speeds and directions: use the global average route wind probability matrix provided by IMO to calculate the wind speed-wind direction average main engine power saving rate and the propulsion efficiency of the main propulsion device;

[0013] S4, solve the model by changing the position of a single sail: change the position of a single sail in a given deck space, and calculate the average main engine power saving rate and propulsion efficiency of the main propulsion device under different wind speed and wind direction conditions of a single sail;

[0014] S5, training model based on artificial neural network algorithm: Using artificial neural network algorithm, a first proxy surface model of wind speed-direction average main engine power saving rate changing with the position of a single sail is trained, and a second proxy surface model of wind speed-direction average main propulsion efficiency changing with the position of a single sail is trained;

[0015] S6, calculating the optimal solution for multi-objective optimization: using a multi-objective genetic algorithm, taking the proxy surface model as the fitness of two objectives, calculating the Pareto optimal solution space of a single sail position as the optimal solution for multi-objective optimization.

[0016] Preferably, in step S2, the wind-assisted propulsion ship performance evaluation model includes: a four-degree-of-freedom mechanical equilibrium equation group constructed based on the set sea conditions and the wind-assisted propulsion ship coordinate system, as well as the relationship between the hydrodynamic and aerodynamic forces acting on the ship and the navigation attitude and effective thrust in the equation group, and the relationship between the relative rotation efficiency, hull efficiency, open water efficiency and effective thrust of the main propulsion device and the propulsion efficiency, effective power, main engine power and main engine power saving rate.

[0017] Preferably, the four-degree-of-freedom mechanical equilibrium equations are:

[0018]

[0019]

[0020] Where, β represents the drift angle; δ represents the rudder angle; represents the heel angle; GM represents high static stability; Δ represents displacement; g represents gravitational acceleration; X CW represents hydrostatic resistance; X AW Indicates wave resistance increase; X Hand Y H They represent the drift angle additional resistance and lateral force respectively; CLR represents the distance from the drift angle additional resistance and lateral force action point to the bow; z H Indicates the Z coordinate of the point where the drift angle additional resistance and lateral force act; X W and Y W Respectively represent the windward forces acting on the hull and superstructure above the waterline; x W 、y W and z W They represent the x-, y-, and z-axis coordinates of the points where the windward force acts on the hull and superstructure above the waterline; S and Y S They represent the thrust and lateral force generated by the wind-assisted propulsion device respectively; x S 、y S and z S Indicates the x-, y-, and z-axis coordinates of the points where the thrust and lateral force generated by the wind-assisted propulsion device are applied; R and Y R Represents the rudder force of x and y axis respectively; z R Indicates the Z coordinate of the point where the rudder force acts; T E Indicates the effective thrust of the main propulsion unit.

[0021] Preferably, the propulsion efficiency η of the main propulsion device is D The calculation method is:

[0022] η D =η R η H η O (5)

[0023] In the main propulsion unit, η R Relative rotation efficiency, η H represents the hull efficiency, η O represents the open water efficiency and η D Indicates propulsion efficiency.

[0024] Preferably, the effective power P of the main propulsion device E The calculation method is:

[0025] P E =T E V S (6)

[0026] The effective thrust T is obtained based on the four-degree-of-freedom mechanical equilibrium equations. E , V S Indicates the speed.

[0027] Preferably, under different wind directions, the main engine power P of the main propulsion device is S_total The calculation method is:

[0028]

[0029] Where η D represents propulsion efficiency; η S Indicates transmission efficiency; P S Indicates the power required for navigation; P S_rotor Indicates the power required to drive the rotor.

[0030] Preferably, the main engine power saving rate of the main propulsion device is calculated as follows:

[0031]

[0032] P S_total,w / o Sail Indicates the required main engine power without wind-assisted propulsion.

[0033] Preferably, in step S3, the wind speed values ​​include: 5m / s, 10m / s and 15m / s; the wind direction values ​​are taken at intervals of 5°, ranging from 0° to 360°.

[0034] Preferably, in step S6, in the multi-objective genetic algorithm, the proxy surface model of the wind speed-wind direction average main engine power saving rate changing with the position of a single sail, the proxy surface model of the wind speed-wind direction average main propulsion device propulsion efficiency changing with the position of a single sail and the constraints are used as input, and the Pareto optimal solution space of a single sail position is used as output, and the constraints include: the radius of the single sail base, the deck space, and the deck space available for arrangement.

[0035] Beneficial effects:

[0036] The present invention proposes a method for optimizing the layout of a single sail of a wind-assisted propulsion ship, which uses a method combining an artificial neural network (ANN) and a multi-objective genetic algorithm (MGA). That is, an AGAINST surface model of the relationship between the saving rate of the main engine power and the layout of a single sail, and an AGAINST surface model of the relationship between the propulsion efficiency of the main propulsion device and the layout of a single sail are constructed using an ANN. Then, using the AGAINST surface as the fitness, a multi-objective genetic algorithm is used to perform multi-objective optimization on the layout of a single sail, and obtain the optimal spatial layout (i.e., position) of a single sail in a given deck space for a given ship, a given single sail, and a given speed. The present invention can achieve multi-objective optimization, i.e., taking into account both the maximization of the saving rate of the main engine power and the maximization of the propulsion efficiency of the main propulsion device. At the same time, it has high efficiency and can be used for feasibility analysis and preliminary design of energy efficiency improvement of wind-assisted propulsion ships. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A flow chart of a method for optimizing the layout of a single sail of a wind-assisted propulsion ship.

[0038] Figure 2 Rendering of the wind-assisted propulsion ship coordinate system in the embodiment.

[0039] Figure 3 Effect diagram of the multi-objective genetic algorithm restriction conditions in the embodiment. DETAILED DESCRIPTION

[0040] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0041] Example 1:

[0042] like Figure 1 As shown, the present invention provides a method for optimizing the layout of a single sail of a wind-assisted propulsion ship:

[0043] S1, parameter setting: given ship type, single sail, speed, and sea conditions as parameters:

[0044] S2, solve the performance evaluation model of wind-assisted propulsion ship: substitute the parameters in S1 into the performance evaluation model of wind-assisted propulsion ship to obtain the main engine power saving rate and the propulsion efficiency of the main propulsion device;

[0045] S3, solve the model by changing wind speed and direction: calculate the main engine power saving rate and the propulsion efficiency of the main propulsion device at different wind speeds and directions: use the global average route wind probability matrix provided by IMO to calculate the wind speed-wind direction average main engine power saving rate and the propulsion efficiency of the main propulsion device;

[0046] S4, solve the model by changing the position of a single sail: change the position of a single sail in a given deck space, and calculate the average main engine power saving rate and propulsion efficiency of the main propulsion device under different wind speed and wind direction conditions of a single sail;

[0047] S5, training model based on artificial neural network algorithm: Using artificial neural network algorithm, a first proxy surface model of wind speed-direction average main engine power saving rate changing with the position of a single sail is trained, and a second proxy surface model of wind speed-direction average main propulsion efficiency changing with the position of a single sail is trained;

[0048] S6, calculating the optimal solution for multi-objective optimization: using a multi-objective genetic algorithm, taking the proxy surface model as the fitness of two objectives, calculating the Pareto optimal solution space of a single sail position as the optimal solution for multi-objective optimization.

[0049] Example 2:

[0050] Given a ship type, a single sail, speed (Vs), wind (TWS and TWA) and waves (TWA, Hs and Tp):

[0051] (1) Solve the wind-assisted propulsion ship performance evaluation model to obtain the main engine power saving rate Rsavings and the main propulsion device propulsion efficiency η D .

[0052] The wind-assisted propulsion ship performance evaluation model includes a four-degree-of-freedom mechanical equilibrium equation system, as well as the relationship between the hydrodynamic and aerodynamic forces acting on the ship, its sailing attitude (rudder angle, drift angle, and heel angle), and effective thrust. The model is detailed below.

[0053] The coordinate system of the wind-assisted propulsion ship is as follows Figure 2 As shown, the coordinate origin is at the bow, the height is the keel, the X axis points to the stern, the Y axis points to the starboard, and the Z axis is vertically upward.

[0054] The positive and negative definitions of ship (including appendages) motion and wind direction angle are as follows:

[0055] (1) Drift angle - the angle between the heading and the heading, with counterclockwise being positive;

[0056] (2) Rudder angle - right rudder is positive;

[0057] (3) Heel angle - positive for left heel;

[0058] (4) Wind direction angle - the angle between the positive direction of the X-axis and the wind direction, with counterclockwise being positive.

[0059] According to this coordinate system and the definition of positive and negative, in a specific sea condition (wind: wind direction TWA, wind speed TWS; wave: three-in-one average wave height H 1 / 3 , peak period T p ) and specific speed V S Under this condition, the ship's four-degree-of-freedom mechanical equilibrium equations are as follows:

[0060]

[0061]

[0062] Where, β represents the drift angle; δ represents the rudder angle; represents the heel angle; GM represents high static stability; Δ represents displacement; g represents gravitational acceleration; X CW represents hydrostatic resistance; X AW Indicates wave resistance increase; X H and Y H They represent the drift angle additional resistance and lateral force respectively; CLR represents the distance from the drift angle additional resistance and lateral force action point to the bow; z H Indicates the Z coordinate of the point where the drift angle additional resistance and lateral force act; X W and Y W Respectively represent the windward forces acting on the hull and superstructure above the waterline; xW 、y W and z W They represent the x-, y-, and z-axis coordinates of the points where the windward force acts on the hull and superstructure above the waterline; S and Y S They represent the thrust and lateral force generated by the wind-assisted propulsion device respectively; x S 、y S and z S Indicates the x-, y-, and z-axis coordinates of the points where the thrust and lateral force generated by the wind-assisted propulsion device are applied; R and Y R Represents the rudder force of x and y axis respectively; z R Indicates the Z coordinate of the point where the rudder force acts; T E Indicates the effective thrust of the main propulsion unit.

[0063] In this set of mechanical equilibrium equations, the relationship between hydrodynamics and aerodynamics and navigation attitude and effective thrust can be obtained using empirical / semi-empirical formulas, or by three-dimensional CFD calculations or model tests.

[0064] This mechanical equilibrium equation group consists of four nonlinear equations, solving β, δ, and T E Four unknown quantities constitute a mathematical closed system.

[0065] Use the Secant Method to solve β, δ, and T E Four unknown quantities. At the same time, the relative rotation efficiency η of the main propulsion device is solved using the empirical formula R , hull efficiency η H and open water efficiency η O , and then use formula (5) to obtain the propulsion efficiency η of the main propulsion device D .

[0066] η D =η R η H η O (5)

[0067] Get effective thrust T E , and then obtain the effective power P E As shown in formula (6).

[0068] P E =T E V S (6)

[0069] According to formula (7), the required main engine power P under different wind directions is obtained: S_total .

[0070]

[0071] Where,

[0072] η D - propulsion efficiency;

[0073] η S -Transmission efficiency;

[0074] P S - Power required for navigation;

[0075] P S_rotor -The power required to drive the rotor.

[0076] At the same time, calculate the required main engine power P without wind auxiliary propulsion device S_total,w / o Sail , and then the host power saving rate is obtained, as shown in formula (8).

[0077]

[0078] (2) Change wind speed TWS and TWA to calculate the main engine power saving rate Rsavings and main propulsion efficiency η D .

[0079] The calculation examples to be calculated are shown in Table 1.

[0080] Table 1

[0081] Wind speed TWS (m / s) Wind direction TWA(°) 5.0 0.0-360.0, 5.0 intervals 10.0 0.0-360.0, 5.0 intervals 15.0 0.0-360.0, 5.0 intervals

[0082] (3) Using the global average route wind probability matrix provided by IMO:

[0083] IMO is derived from (IMO-MEPC.1-Circ.896-2021Guidance On Treatment Of InnovativeEnergy Efficiency Technologies for Calculation and Verification of theAttainedEEDI and EEXI), which calculates the wind speed-wind direction average (TWS- and TWA-averaged) main engine power savings rate Rsavings and the main propulsion efficiency η D .

[0084] First calculate the average (TWA-averaged) main engine power saving rate Rsavings and main propulsion efficiency η under different wind speeds TWS D , as shown in formulas (9)-(14).

[0085]

[0086] TWA-averaged Rsavings 15m / s = (11)

[0087] wa0Rsavings 15m / s,0 +wa5Rsavings 15m / s,5 +wa 10 Rsavings 15m / s,10 +...+wa 355

[0088] Rsavings 15m / s,355

[0089]

[0090] Among them, the weight wa is:

[0091] Table 2

[0092]

[0093]

[0094]

[0095] Then calculate the main engine power saving rate Rsavings and the main propulsion efficiency η of the wind speed-wind direction average (TWS-and TWA-averaged) D , as shown in formulas (15)-(16).

[0096]

[0097]

[0098] Among them, the weight ws value is shown in Table 3:

[0099] Table 3

[0100] <![CDATA[ws 5m / s ]]> 0.539 <![CDATA[ws 10m / s ]]> 0.3878 <![CDATA[ws 15m / s ]]> 0.0692

[0101] (IV) Change the position of a single sail in the deck space available for arrangement (50 positions are recommended) and calculate the main engine power saving rate Rsavings and the main propulsion efficiency η under different positions, the wind speed-wind direction average (TWS-and TWA-averaged) D .

[0102] (5) Using the artificial neural network algorithm, two proxy surface models are trained: the wind speed-wind direction average main engine power saving rate changes with the position of a single sail, and the wind speed-wind direction average main propulsion efficiency changes with the position of a single sail.

[0103] Divide the data collected in step (4) into a training set and a test set. If there are 50 sets of data in total, it is recommended to use 42 sets as training sets and the rest as test sets.

[0104] In the process of programming, the execution of artificial neural network algorithms can call existing modules of programming tools. Taking Matlab as an example, the newff function can be called to construct the artificial neural network structure and return the artificial neural network type object. The train function of the object can be called to train the proxy face model with the training data set and calculate the accuracy of the proxy face model with the test set to obtain R 2 , MAE and MSE three indicators.

[0105] (6) Using a multi-objective genetic algorithm, with the fitness of the two proxy surface models mentioned above as the two objectives, the Pareto optimal solution space (Pareto Solutions) of a single sail position is calculated to achieve multi-objective optimization of the wind speed-wind direction average main engine power saving rate and the propulsion efficiency of the main propulsion device.

[0106] In the process of programming, the execution of the multi-objective genetic algorithm can call the existing modules of the programming tool. Taking Matlab as an example, the gamultiobj function can be called, with the proxy surface model of the wind speed-wind direction average main engine power saving rate changing with the position of a single sail, the proxy surface model of the wind speed-wind direction average main propulsion efficiency changing with the position of a single sail, and the constraint conditions as input, and the Pareto optimal solution space of a single sail position as output. Figure 3 As shown in Figure 3, the constraints of the multi-objective genetic algorithm include: the radius of a single sail base, deck space, and deck space available for layout.

[0107] It should be noted that the above-mentioned specific embodiments can enable those skilled in the art to more fully understand the present invention.

[0108] Therefore, although this specification has described the present invention in detail with reference to the drawings and embodiments, it should be understood by those skilled in the art that the present invention may still be modified or replaced with equivalents. In short, all technical solutions and improvements that do not depart from the spirit and scope of the present invention should be included in the scope of protection of the patent for the present invention.

Claims

1. A method for optimizing the layout of a single sail of a wind-assisted propulsion ship, characterized in that: S1, parameter setting: given ship type, single sail, speed, and sea conditions as parameters: S2, solve the performance evaluation model of wind-assisted propulsion ship: substitute the parameters in S1 into the performance evaluation model of wind-assisted propulsion ship to obtain the main engine power saving rate and the propulsion efficiency of the main propulsion device; S3, solve the model by changing wind speed and direction: calculate the main engine power saving rate and the propulsion efficiency of the main propulsion device at different wind speeds and directions: use the global average route wind probability matrix provided by IMO to calculate the wind speed-wind direction average main engine power saving rate and the propulsion efficiency of the main propulsion device; S4, solve the model by changing the position of a single sail: change the position of a single sail in a given deck space, and calculate the average main engine power saving rate and propulsion efficiency of the main propulsion device under different wind speed and wind direction conditions of a single sail; S5, training model based on artificial neural network algorithm: Using artificial neural network algorithm, a first proxy surface model of wind speed-direction average main engine power saving rate changing with the position of a single sail is trained, and a second proxy surface model of wind speed-direction average main propulsion efficiency changing with the position of a single sail is trained; S6, calculating the optimal solution for multi-objective optimization: using a multi-objective genetic algorithm, taking the proxy surface model as the fitness of two objectives, calculating the Pareto optimal solution space of a single sail position as the optimal solution for multi-objective optimization.

2. A method for optimizing the layout of a single sail of a wind-assisted propulsion ship according to claim 1, characterized in that: In step S2, the wind-assisted propulsion ship performance evaluation model includes: a four-degree-of-freedom mechanical equilibrium equation group constructed based on the set sea conditions and the wind-assisted propulsion ship coordinate system, as well as the relationship between the hydrodynamic and aerodynamic forces acting on the ship and the navigation attitude and effective thrust in the equation group, and the relationship between the relative rotation efficiency, hull efficiency, open water efficiency and effective thrust of the main propulsion device and the propulsion efficiency, effective power, main engine power and main engine power saving rate.

3. A method for optimizing the layout of a single sail of a wind-assisted propulsion ship according to claim 2, characterized in that: The four-degree-of-freedom mechanical equilibrium equations are: Where, β represents the drift angle; δ represents the rudder angle; represents the heel angle; GM represents high static stability; Δ represents displacement; g represents gravitational acceleration; X CW represents hydrostatic resistance; X AW Indicates wave resistance increase; X H and Y H They represent the drift angle additional resistance and lateral force respectively; CLR represents the distance from the drift angle additional resistance and lateral force action point to the bow; z H Indicates the Z coordinate of the point where the drift angle additional resistance and lateral force act; X W and Y W Respectively represent the windward forces acting on the hull and superstructure above the waterline; x W 、y W and z W They represent the x-, y-, and z-axis coordinates of the points where the windward force acts on the hull and superstructure above the waterline; S and Y S They represent the thrust and lateral force generated by the wind-assisted propulsion device respectively; x S 、y S and z S Indicates the x-, y-, and z-axis coordinates of the points where the thrust and lateral force generated by the wind-assisted propulsion device are applied; R and Y R Represents the rudder force of x and y axis respectively; z R Indicates the Z coordinate of the point where the rudder force acts; T E Indicates the effective thrust of the main propulsion unit.

4. A method for optimizing the layout of a single sail of a wind-assisted propulsion ship according to claim 2, characterized in that: The propulsion efficiency η of the main propulsion device D The calculation method is: or D =the R or H or O (5) In the main propulsion unit, η R Relative rotation efficiency, η H represents the hull efficiency, η O represents the open water efficiency and η D Indicates propulsion efficiency.

5. A method for optimizing the layout of a single sail of a wind-assisted propulsion ship according to claim 2, characterized in that: The effective power P of the main propulsion device E The calculation method is: P E =T E V S (6) The effective thrust T is obtained based on the four-degree-of-freedom mechanical equilibrium equations. E , V S Indicates the speed.

6. A method for optimizing the layout of a single sail of a wind-assisted propulsion ship according to claim 5, characterized in that: Under different wind directions, the main propulsion power P S_total The calculation method is: Where η D Indicates propulsion efficiency; η S Indicates transmission efficiency; P S Indicates the power required for navigation; P S_rotor Indicates the power required to drive the rotor.

7. A method for optimizing the layout of a single sail of a wind-assisted propulsion ship according to claim 6, characterized in that: The calculation method of the main engine power saving rate of the main propulsion device is: P S_total,w / oSail Indicates the required main engine power without wind-assisted propulsion.

8. A method for optimizing the layout of a single sail of a wind-assisted propulsion ship according to claim 1, characterized in that: In step S3, the wind speed values ​​include: 5m / s, 10m / s, and 15m / s; the wind direction values ​​are intervals of 5°, ranging from 0° to 360°.

9. A method for optimizing the layout of a single sail of a wind-assisted propulsion ship according to claim 1, characterized in that: In step S6, in the multi-objective genetic algorithm, a proxy surface model of the wind speed-wind direction average main engine power saving rate changing with the position of a single sail, a proxy surface model of the wind speed-wind direction average main propulsion device propulsion efficiency changing with the position of a single sail, and constraints are used as input, and the Pareto optimal solution space of a single sail position is used as output. The constraints include: the radius of the base of a single sail, the deck space, and the deck space available for arrangement.

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