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

Abstract

The invention relates to the technical field of ship energy saving, in particular to a wind-assisted propulsion ship energy-saving effect calculation method, which comprises the following steps of: setting an ideal condition based on an empirical value to obtain an iteration initial value; based on the four-degree-of-freedom mechanical equilibrium equation set, constructing a linear equation set of a generalized secant method, and calculating a weight matrix; weighting the iteration initial value to obtain an iteration result; calculating iteration condition parameters and carrying out forward iteration; iteration condition judgment is carried out, when the iteration condition is met, the iteration process continues to be executed, and when the iteration condition is not met, a first iteration initial value is output. The method adapts to the complexity of an equation set expression in a wind-assisted propulsion ship energy-saving effect evaluation model, is easy to apply, can avoid the occurrence of an ill-conditioned matrix in an iteration process, and is fast in convergence and accurate in result.

Description

Technical Field

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

[0002] The energy-saving effect evaluation model of wind-assisted propulsion ships includes a set of four-degree-of-freedom mechanical equilibrium equations, as well as the relationship between the hydrodynamic force / aerodynamic force on the ship and the navigation attitude (rudder angle, drift angle, heel angle) and effective thrust in the equations. The model is as follows.

[0003] The coordinate system of the wind-assisted propulsion ship is as follows Figure 1 As shown, the origin of the coordinate system is at the bow, the height is at the keel, the X-axis points to the stern, the Y-axis points to the starboard, and the Z-axis points vertically upward.

[0004] The positive and negative definitions of the ship (including appendages) motion and the wind direction angle are as follows:

[0005] (1) Drift angle - the angle between heading and heading, with counterclockwise being positive;

[0006] (2) Rudder angle: right rudder is positive;

[0007] (3) Heel angle: positive for left heel;

[0008] (4) Wind direction angle - the angle between the positive direction of the X-axis and the wind direction, with counterclockwise being positive.

[0009] According to this coordinate system and the definition of positive and negative, in a specific sea condition (wind: true wind direction TWA, true wind speed TWS; wave: Trinity 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:

[0010]

[0011]

[0012] In the formula,

[0013] β-drift angle;

[0014] δ-rudder angle;

[0015] - heel angle;

[0016] GM-high static stability;

[0017] △-displacement;

[0018] g - acceleration due to gravity;

[0019] XCw - hydrostatic resistance;

[0020] X AW - wave resistance;

[0021] X H and Y H - Additional resistance and lateral force due to drift angle;

[0022] CLR - the distance from the drift angle additional resistance and the side force application point to the bow;

[0023] z H - Z coordinate of the point of action of the drift angle additional resistance and lateral force;

[0024] X w and Y w - windward forces on the hull and superstructure above the waterline;

[0025] X W ,y W and z W - Coordinates of the points above the waterline where the windward forces act on the hull and superstructure;

[0026] X S and Y S -Thrust and lateral force generated by wind-assisted propulsion devices;

[0027] x S ,y S and z S - Coordinates of the points of action of the thrust and lateral forces generated by the wind-assisted propulsion device;

[0028] X R and Y R - Rudder force;

[0029] z R -Z coordinate of the point where the rudder force acts;

[0030] T E - effective thrust of the main propulsion unit;

[0031] L PP - Length between perpendiculars of the ship.

[0032] In this set of mechanical equilibrium equations, the relationship between hydrodynamics and aerodynamics and navigation attitude and effective thrust can be obtained by adopting low / mid fidelity (Low / mid Fidelity) methods, such as empirical / semi-empirical formulas, or by high fidelity methods (High Fidelidy), such as three-dimensional CFD calculations or model tests.

[0033] This mechanical equilibrium equation group consists of four nonlinear equations. Solving β, δ, and TE Four unknown quantities constitute a mathematical closed system. Since the unknown quantities in this model are highly coupled and have implicit relationships with each other, numerical algorithms are required to solve them. The calculation method requires:

[0034] (I) Adapting to the complexity of the equations in the energy-saving effect evaluation model of wind-assisted propulsion ships;

[0035] (ii) The iterative process avoids the occurrence of ill-conditioned matrices;

[0036] (iii) Rapid convergence;

[0037] (iv) The results are accurate (the right side of the equal sign of the mechanical equilibrium equations returns to zero and the numerical value should be a minimum).

[0038] The existing calculation method of energy-saving effect of wind-assisted propulsion ships, that is, the solution of energy-saving effect evaluation model, includes direct solution using nonlinear equation root-finding algorithm, and also first converting the equation root-finding problem into function extreme value problem and then solving it.

[0039] The nonlinear equation group root-finding algorithm is used to solve directly, including Newton-Raphson Method, Fixed-point Reration Method, Secant Method, etc. Among them, the Newton method needs to find derivatives, which cannot cope with the complexity of the equation group expression in the energy-saving effect evaluation model; the fixed-point iteration method converges slowly, and an initial iteration range across positive and negative values ​​needs to be given. In solving the energy-saving effect evaluation model, it is difficult to invent a calculation method for the initial iteration range to ensure that the iteration process does not have an ill-conditioned matrix and finally converges to the correct value; the secant method does not need to find derivatives and converges quickly, but whether the iteration process has an ill-conditioned matrix and whether it converges to the correct value depends on the selection of the iteration initial value. At present, the iteration initial value mainly relies on enumeration attempts, and there is no fixed iteration initial value calculation method.

[0040] The solution is to first convert the root-finding problem of the system of equations into the problem of finding the extreme value of a function, and then solve it. The current solution is mainly the Nelder-Mead Simplex algorithm. The details are as follows.

[0041] Formulas (1)-(4) can be simplified to the form of formulas (5)-(8):

[0042]

[0043] Formula (5)-(8) is equivalent to formula (9):

[0044]

[0045] This is equivalent to the function The minimum value is reached. Therefore, the problem of finding the root of the system of equations is transformed into finding the function The minimum value problem is solved by applying the Nelder-Mead Simplex algorithm. After research, it is found that when this method is applied to solve the energy-saving effect evaluation model, the convergence is poor and it is difficult to converge to the correct value, that is, the rudder angle δ, drift angle β, and heel angle obtained by the final solution are Substituting the effective thrust TE into equations (1)-(4), the right side of the equal sign does not return to zero. Summary of the invention

[0046] In order to solve the technical problem in the prior art that, when the Nelder-Mead Simp1ex algorithm is applied to solve the energy-saving effect evaluation model, the convergence is poor and it is difficult to converge to the correct value, the present invention proposes a method for calculating the energy-saving effect of a wind-assisted propulsion ship, and combines the secant method to perform initial value iteration, so as to solve the energy-saving effect evaluation model of the wind-assisted propulsion ship to obtain the energy-saving effect.

[0047] The present invention is achieved through the following technical solutions:

[0048] A method for calculating energy saving effect of a wind-assisted propulsion ship comprises the following steps:

[0049] Step 1: Initialize the iterative program, set iter = 1, and give the independent variables rudder angle δ, drift angle β, heel angle Effective thrust T E The independent variable residual_x, the dependent variable combined force ∑F X ,∑F Y and resultant moment ΣM Z ,∑M X The dependent variable residual_f is assigned a residual initial value, and the residual initial value is any value greater than the convergence criterion.

[0050] Step 2: Set ideal conditions based on experience to obtain the rudder angle δ, drift angle β, and heel angle under ideal conditions. Effective thrust T E The initial value of the iteration

[0051] Iteration initial value The construction method is:

[0052] The first step is to set an ideal condition based on experience, including:

[0053] Consider the initial hydrostatic resistance X CW0 and wave resistance X AW0 is a constant;

[0054] It is considered that the windward force on the hull and superstructure above the waterline is X w , Y w It has nothing to do with the drift angle. Let β = 0 and calculate X W0 , Y W0 The coordinates of the points above the waterline where the windward force on the hull and superstructure is applied are x W0 ,y W0 , Z W0

[0055] Consider the wind-assisted propulsion device rotor sail thrust X S and lateral force Y S Independent of the drift angle and the heel angle, let β = 0 and Calculate X S0 , Y S0 The coordinates of the points of action of the thrust and lateral force generated by the wind-assisted propulsion device are x S0 ,y S0 , Z S0 ;

[0056] The additional resistance of the steering force is X R and lateral force Y R Regardless of the effective thrust, let T E0 =0, we get:

[0057] (1)X R0 (δ, β, T E )=X R0 (δ, β);

[0058] (2)Y R0 (δ, β, T E )=Y R0 (δ, β);

[0059] It is assumed that the distance CLR0 from the point of action of the drift angle additional force to the bow is almost 0, and the distance Z from the rudder additional force and the drift angle additional force to the keel is R0 and Z H0 All are 1 / 2 draft, which is a constant;

[0060] In the second step, based on the parameters under ideal conditions obtained in the first step, the initial four-degree-of-freedom mechanical equilibrium equations are constructed as shown in equations (10)-(13):

[0061] ∑F X0 =X CW0 +X AW0 +X H0 (β0)+X W0 +X S0 +X R0 (δ0, β0) (10)

[0062] +T E0=0

[0063] ∑F Y0 =Y H0 (β0)+Y R0 (δ0,β0)+Y S0 +Y w0 =0 (11)

[0064]

[0065] Equations (11)-(13) form a linear system, as shown in equation (14):

[0066]

[0067] The third step is to solve the linear system obtained in the second step and obtain

[0068] The fourth step is based on Obtain

[0069] Step 5: According to Find X H0 (β0) and X R0 (δ0, β0);

[0070] Step 6: X H0 (β0) and X R0 Substituting (δ0, β0) into equation (10), we can obtain T E0 .

[0071] At this point, the first iteration initial value is obtained

[0072] Step 3: Iteration initial value based on step 2 Change any one of the parameters, keep the other parameters unchanged, and get the other 4 iterative initial values k=1, 2, 3, 4.

[0073] Specifically, the other 4 iteration initial values The construction method for k=1, 2, 3, 4 is:

[0074] (1)

[0075] (2)

[0076] (3)

[0077] (3)

[0078] According to experience, q is taken as 10%.

[0079] At this point, all five sets of iterative initial values ​​are obtained.

[0080] According to the calculation experience under actual working conditions, based on the iterative initial values ​​constructed in steps 2 and 3, no ill-conditioned matrix will appear during the iteration process and the correct result can be converged.

[0081] Step 4: Based on the five iteration initial values, an iteration set is formed. k=0,1,2,3,4,determine whether the set meets the iteration conditions. If so, perform weighted iteration based on the generalized secant method. If not, output the result of the first iteration initial value.

[0082] The iteration condition is: iter<maximum number of iteration steps, independent variable residual_x>convergence criterion, dependent variable residual_f>convergence criterion are satisfied at the same time.

[0083] Step 5, construct the linear equation system Ap=b of the generalized secant method and solve for p;

[0084] Where A is a parameter matrix constructed based on the iterative set according to the ship's four-degree-of-freedom mechanical equilibrium equations, b is a constant term matrix, and the weight matrix p = {p0, p1, p2, p3, p4} T .

[0085] Specifically, the method for constructing the expressions of A and b of the linear equation system Ap=b is:

[0086]

[0087] The generalized secant method equation constructed based on step 5 does not require derivative calculation, is easy to use, and adapts to the complexity of the equation group expression in the wind-assisted propulsion ship energy-saving effect evaluation model. And the secant method is used for calculation, and the convergence speed is fast. In the present invention, if the convergence condition is set to 10 -8 , it can basically converge within 20 steps.

[0088] Step 6: Based on the weight matrix p obtained in step 5, weight the 5 groups of iterations to get the iteration result

[0089] Specifically, the The calculation method is as shown in formula (19):

[0090]

[0091] Step 7: The iterative result obtained in step 6 Substitute into the ship's four-degree-of-freedom mechanical equilibrium equations, such as equations (1)-(4), and calculate ∑Fx, ∑Fy, ∑Mz, and ∑Mx.

[0092]

[0093] Step 8: Based on the result from step 6 And ∑Fx, ∑Fy, ∑Mz, ∑Mx obtained in step 7, calculate the independent variable residual_x and the dependent variable residual_f.

[0094] Specifically, the calculation method of the independent variable residual_x is as shown in formula (17):

[0095]

[0096] The calculation method of the dependent variable residual_f is as shown in formula (18):

[0097]

[0098] Step nine, and k=1,2,3,4; form a new iteration set k=1,2,3,4,5; reassign the iterated set forward to obtain k=1, 2, 3, 4, 5; the assignment method is: k=1, 2, 3, 4, 5, and iter++, return to step 4 to re-judge the iteration condition.

[0099] Further, after the step 4 determines that the iteration condition is not satisfied and outputs the result, based on the output first iteration initial value The following methods are used to calculate the fuel savings for a specific flight:

[0100] The first step is to obtain the effective thrust T based on step 4 E , and then calculate the effective power P E and the required host power P S ;

[0101] The second step is to calculate the required main engine power with and without the wind-assisted propulsion device to obtain the energy-saving effect of the wind-assisted propulsion device;

[0102] The third step is to calculate the power saving and energy saving effect under different wind speeds and wind directions;

[0103] The fourth step is to calculate the power savings for a specific voyage by applying the Global Wind Probability Matrix (Global Wind Probability Matrix) recommended by IMO.

[0104] The fifth step is to calculate the fuel savings for a specific voyage using the ship's fuel consumption rate SFOC.

[0105] The beneficial effects of the present invention are:

[0106] (I) Adapting to the complexity of the equation expression in the energy-saving effect evaluation model of wind-assisted propulsion ships; adopting this scheme, there is no need to take derivatives, and there is no need to transform the root-finding problem of the nonlinear equation group into the problem of finding the minimum value of the function. The mathematical principles are easy to understand and easy to apply.

[0107] (ii) The iterative process avoids the occurrence of ill-conditioned matrices.

[0108] (III) Faster convergence; if the convergence condition is set to 10 -8 , then it can basically converge within 20 steps. It can converge to the correct value, that is, the final solution of the rudder angle δ, drift angle β, heel angle Substituting the effective thrust TE into equations (1)-(4), the right side of the equal sign can return to zero, and the numerical value is a minimum.

[0109] (iv) The results are accurate (the right side of the equal sign of the mechanical equilibrium equations returns to zero and the numerical value should be a minimum). BRIEF DESCRIPTION OF THE DRAWINGS

[0110] Figure 1 Coordinate system for wind-assisted propulsion ships.

[0111] Figure 2 The algorithm flow chart of the energy-saving effect evaluation model for wind-assisted propulsion ships is solved using the secant method. DETAILED DESCRIPTION

[0112] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0113] The present invention discloses a method for calculating the energy-saving effect of a wind-assisted propulsion ship, which combines the secant method to perform initial value iteration, thereby solving a wind-assisted propulsion ship energy-saving effect evaluation model, so as to achieve the effects of adapting to the complexity of the equation group expression in the wind-assisted propulsion ship energy-saving effect evaluation model, being easy to use, being able to avoid the occurrence of ill-conditioned matrices in the iterative process, fast convergence, and accurate results. The algorithm flow of the present invention is as follows Figure 2 As shown, the following steps are included:

[0114] Step 1: Initialize the iterative program, set iter = 1, and give the independent variables rudder angle δ, drift angle β, heel angle Effective thrust T E The independent variable residual_x, the dependent variable combined force ∑F X ,∑F Y and resultant moment ΣM Z ,∑M x The dependent variable residual_f is assigned a residual initial value, and the residual initial value is any value greater than the convergence standard;

[0115] Step 2: Set ideal conditions based on experience to obtain the rudder angle δ, drift angle β, and heel angle under ideal conditions. Effective thrust T E The initial value of the iteration

[0116] Specifically, the iteration initial value The construction method is:

[0117] The first step is to set an ideal condition based on experience, including:

[0118] Consider the initial hydrostatic resistance X CW0 and wave resistance X AW0 is a constant;

[0119] Assuming that the windward forces Xw and Yw on the hull and superstructure above the waterline have nothing to do with the drift angle, let β = 0 and calculate X W0 , Y W0 The coordinates of the points above the waterline where the windward force on the hull and superstructure is applied are x W0 ,y W0 , Z W0 ;

[0120] Consider the wind-assisted propulsion device rotor sail thrust X S and lateral force Y S Independent of the drift angle and the heel angle, let β = 0 and Calculate X S0 , Y S0 The coordinates of the points of action of the thrust and lateral force generated by the wind-assisted propulsion device are x S0 ,y S0 , Z S0

[0121] The additional resistance of the steering force is X R and lateral force Y R Regardless of the effective thrust, let T E0 =0, we get:

[0122] (1)X R0 (δ, β, T E)=X R0 (δ, β);

[0123] (2)Y R0 (δ, β, T E )=Y R0 (δ, β);

[0124] It is assumed that the distance CLR0 from the point of action of the drift angle additional force to the bow is almost 0, and the distance from the steering additional force and the drift angle additional force to the keel is z R0 and z H0 All are 1 / 2 draft, which is a constant;

[0125] In the second step, based on the parameters under ideal conditions obtained in the first step, the initial four-degree-of-freedom mechanical equilibrium equations are constructed as shown in equations (10)-(13):

[0126] ∑F x0 =X CW0 +X AW0 +X H0 (β0)+X W0 +X S0 +X R0 (δ0,β0) (10)+T E0 =0

[0127] ∑F Y0 =Y H0 (β0)+Y R0 (δ0,β0)+Y S0 +Y W0 =0 (11)

[0128]

[0129] It can be seen that equations (11)-(13) form a linear system Ax=b, as shown in equation (14):

[0130]

[0131] Among them, X H and Y H is the additional resistance and lateral force of the drift angle, GM is the high static stability, △ is the displacement, g is the gravitational acceleration, L PP It is the length between perpendicular lines of the ship.

[0132] The third step is to solve this linear system and obtain:

[0133] The fourth step is based on Obtain

[0134] Step 5: According to Find X H0(β0) and X R0 (δ0, β0).

[0135] Step 6: X H0 (β0) and X R0 Substituting (δ0, β0) into equation (10), we can obtain T E0 .

[0136] At this point, the iteration initial value Sure.

[0137] Step 3: Iteration initial value based on step 2 Change any one of the parameters, keep the other parameters unchanged, and get the other 4 iterative initial values k = 1, 2, 3, 4;

[0138] Specifically, the other 4 iteration initial values The construction method for k=1, 2, 3, 4 is:

[0139] (1)

[0140] (2)

[0141] (3)

[0142] (3)

[0143] Here, q is a percentage, and experience shows that 10% is appropriate.

[0144] At this point, all five sets of iterative initial values ​​have been determined.

[0145] According to the calculation experience under actual working conditions, based on the iterative initial values ​​constructed in steps 2 and 3, no ill-conditioned matrix will appear during the iteration process and the correct result can be converged.

[0146] Step 4: Based on the five iteration initial values, an iteration set is formed. k==0, 1, 2, 3, 4, determine whether the set meets the following iteration conditions:

[0147] At the same time, iter<maximum number of iterations, independent variable residualx> convergence criteria, and dependent variable residual_f> convergence criteria are satisfied.

[0148] If the iteration conditions are met, weighted iteration is performed based on the generalized secant method. If the iteration conditions are not met, the output result is the initial value of the first iteration.

[0149] Step 5: Construct the linear equation system Ap=b of the generalized secant method and solve for p.

[0150] Where A is a parameter matrix constructed based on the iterative set according to the ship's four-degree-of-freedom mechanical equilibrium equations, b is a constant term matrix, and the weight matrix p = {p0, p1, p2, p3, p4} T .

[0151] Specifically, the expressions of A and b in the linear equation system Ap=b are respectively as shown in equations (15) and (16):

[0152]

[0153] The generalized secant method equation constructed based on step 5 does not require derivative calculation, is easy to use, and adapts to the complexity of the equation group expression in the wind-assisted propulsion ship energy-saving effect evaluation model. And the secant method is used for calculation, and the convergence speed is fast. In the present invention, if the convergence condition is set to 10 -8 , it can basically converge within 20 steps.

[0154] Step 6: Based on the weight matrix p obtained in step 5, weight the 5 groups of iterations to get the iteration result

[0155] Specifically, the calculation method is as follows:

[0156]

[0157] Step 7: Substitute into formulas (1)-(4) and calculate ∑Fx, ∑Fy, ∑Mz, ∑Mx.

[0158] Step 8: Calculate the independent variable residual x and the dependent variable residual f.

[0159] Specifically, the calculation method of the independent variable residual_x is as follows:

[0160]

[0161] The calculation method of the dependent variable residual_f is as follows:

[0162]

[0163] Step nine, and k=1,2,3,4; form a new iteration set k=1,2,3,4,5; reassign the iterated set forward to obtain k=1, 2, 3, 4, 5; the assignment method is: k=1, 2, 3, 4, 5, and iter++, return to step 4 to re-judge the iteration condition.

[0164] Furthermore, after the step 4 determines that the iteration condition is not satisfied and outputs the result, the output result can be used to The fuel savings for a specific flight are obtained as follows:

[0165] According to the effective thrust T E , and then obtain the effective power P E and the required host power P S . The required main engine power is calculated with and without wind-assisted propulsion devices to obtain the energy-saving effect of wind-assisted propulsion devices, and the coupling between the hull, main propeller and wind-assisted propulsion devices is analyzed under typical meteorological conditions and typical wind-assisted propulsion device layouts. The power savings and energy-saving effects under different wind speeds and wind directions are calculated, and the power savings for a specific voyage can be obtained by applying the Global Wind Probability Matrix recommended by IMO for the global average route wind speed and direction probability matrix. Finally, the fuel savings for a specific voyage can be obtained by using the ship fuel consumption rate SFOC.

[0166] It should be noted that the above-described specific implementations can enable those skilled in the art to more fully understand the invention, but do not limit the invention in any way. Therefore, although this specification has described the invention in detail with reference to the drawings and embodiments, those skilled in the art should understand that the invention can still be modified or replaced by equivalents. In short, all technical solutions and improvements that do not deviate from the spirit and scope of the invention should be included in the protection scope of the patent for the invention.

Claims

1. A method for calculating the energy saving effect of a wind-assisted propulsion ship, characterized in that: Step 1: Initialize the iterative program, set iter = 1, and give the independent variables rudder angle δ, drift angle β, heel angle Effective thrust T E The independent variable residual_x, the dependent variable combined force ∑F X ,∑F Y and resultant moment ΣM Z ,∑M X The dependent variable residual_f is assigned a residual initial value, and the residual initial value is any value greater than the convergence standard; Step 2: Set ideal conditions based on experience to obtain the rudder angle δ, drift angle β, and heel angle under ideal conditions. Iterative initial value of effective thrust TE Step 3: Iteration initial value based on step 2 Change any one of the parameters, keep the other parameters unchanged, and get the other 4 iterative initial values Step 4: Based on the five iteration initial values, an iteration set is formed. Determine whether the set meets the iteration conditions. If so, perform weighted iteration based on the generalized secant method. If not, output the result of the first iteration initial value. The iteration condition is: iter < maximum number of iteration steps, independent variable residual_x > convergence standard, dependent variable residual_f > convergence standard are satisfied at the same time; Step 5, construct the linear equation system Ap=b of the generalized secant method and solve for p; Where A is a parameter matrix constructed based on the iterative set according to the ship's four-degree-of-freedom mechanical equilibrium equations, b is a constant term matrix, and the weight matrix p = {p0, p1, p2, p3, p4} T ; Step 6: Based on the weight matrix p obtained in step 5, weight the 5 groups of iterations to get the iteration result Step 7: The iterative result obtained in step 6 Substitute into the ship's four-degree-of-freedom mechanical equilibrium equations to calculate ∑Fx, ∑Fy, ∑Mz, and ∑Mx; Step 8: Based on the result from step 6 And ∑Fx, ∑Fy, ∑Mz, ∑Mx obtained in step 7, calculate the independent variable residual_x and the dependent variable residual_f; Step 9: and Composing a new iterable collection Reassign the iterable collection forward to get The assignment method is: And iter++, return to step 4 to re-judge the iteration condition.

2. A method for calculating energy saving effect of a wind-assisted propulsion ship based on claim 1, characterized in that: In the step 2, the initial value of the iteration The construction method is: The first step is to set an ideal condition based on experience, including: Consider the initial hydrostatic resistance X CW0 and wave resistance X AW0 is a constant; It is considered that the windward force on the hull and superstructure above the waterline is X W , Y W It has nothing to do with the drift angle. Let β = 0 and calculate X W0 , Y W0 The coordinates of the points above the waterline where the windward force on the hull and superstructure is applied are x W0 ,y W0 , z W0 ; Consider the wind-assisted propulsion device rotor sail thrust X S and lateral force Y S Independent of the drift angle and the heel angle, let β = 0 and Calculate X S0 , Y S0 The coordinates of the points of action of the thrust and lateral force generated by the wind-assisted propulsion device are x S0 ,y S0 , z S0 ; The steering force additional resistance is X R and lateral force Y R Regardless of the effective thrust, let T E0 =0, we get: (1)X R0 (δ, β, T E )=X R0 (d, b); (2)Y R0 (δ, β, T E )=Y R0 (d, b); It is assumed that the distance CLR0 from the point of action of the drift angle additional force to the bow is almost 0, and the distance from the steering additional force and the drift angle additional force to the keel is z R0 and z H0 All are 1 / 2 draft, which is a constant; In the second step, based on the parameters under ideal conditions obtained in the first step, the initial four-degree-of-freedom mechanical equilibrium equations are constructed as shown in equations (10)-(13): ∑F Y0 =Y H0 (β0)+Y R0 (δ0,β0)+Y S0 +Y W0 =0 (11) Among them, X H and Y H is the additional resistance and lateral force of the drift angle, GM is the high static stability, △ is the displacement, g is the gravitational acceleration, L PP is the length between perpendicular lines of the ship; Equations (11)-(13) form a linear system, as shown in equation (14): The third step is to solve the linear system obtained in the second step and obtain The fourth step is based on Obtain Step 5: According to Find X H0 (β0) and X R0 (δ0, β0); Step 6: X H0 (β0) and X R0 Substituting (δ0,β0) into equation (10), we can obtain T E0 .

3. A method for calculating energy saving effect of a wind-assisted propulsion ship based on claim 1, characterized in that: In step 3, the other 4 iteration initial values The construction method is: (1) (2) (3) (3) According to experience, q is taken as 10%.

4. A method for calculating energy saving effect of a wind-assisted propulsion ship based on claim 1, characterized in that: In the step 5, the method for constructing the expressions of A and b of the linear equation system Ap=b is:

5. A method for calculating energy saving effect of a wind-assisted propulsion ship based on claim 1, characterized in that: In the step six, the The calculation method is as shown in formula (19):

6. A method for calculating energy saving effect of a wind-assisted propulsion ship based on claim 1, characterized in that: In step 7, the ship's four-degree-of-freedom mechanical equilibrium equations are as follows:

7. A method for calculating energy saving effect of a wind-assisted propulsion ship based on claim 1, characterized in that: In step eight, the calculation method of the independent variable residual_x is as shown in formula (17):

8. A method for calculating energy saving effect of a wind-assisted propulsion ship based on claim 1, characterized in that: In step eight, the dependent variable residual_f is calculated as shown in formula (18):

9. A method for calculating the fuel savings for a specific flight based on any of the methods of claims 1-8, characterized in that: The first step is to obtain the effective thrust T based on step 4 E , and then calculate the effective power P E and the required host power P S ; The second step is to calculate the required main engine power with and without the wind-assisted propulsion device to obtain the energy-saving effect of the wind-assisted propulsion device; The third step is to calculate the power saving and energy saving effect under different wind speeds and wind directions; The fourth step is to calculate the power savings for a specific voyage by applying the Global Wind Probability Matrix (Global Wind Probability Matrix) recommended by IMO. The fifth step is to calculate the fuel savings for a specific voyage using the ship's fuel consumption rate SFOC.

Images