A method for evaluating EEDI contribution of airfoil sails based on actual ship sea trials

Abstract

The invention discloses a method for evaluating the EEDI contribution of a wing-shaped sail based on actual ship sea trials, and relates to the technical field of ships. The method comprises: conducting actual ship performance tests on ships equipped with sails to obtain main engine power required to maintain a target speed when the sails are in different operating states at various relative wind direction angles; obtaining a net thrust test coefficient of the sail at various relative wind direction angles at the target speed based on the main engine power; obtaining a net thrust simulation coefficient curve of the sail at various relative wind direction angles at the target speed based on a four-degree-of-freedom motion model of the ship; comparing the net thrust simulation coefficient curve of the sail with the net thrust test coefficient of the sail to establish a revised four-degree-of-freedom motion model of the ship in a sail-raising operating state; and calculating sail thrust matrix elements and sail EEDI contribution corresponding to a reference speed and any combination of wind field conditions based on the four-degree-of-freedom motion model of the ship in the sail-raising operating state and the four-degree-of-freedom motion model of the ship without sails. The method has the characteristics of being objective, realistic, and operational.

Description

Technical Field

[0001] The present invention relates to the field of ship technology, and in particular to a method for evaluating EEDI contribution of a wing-shaped sail based on actual ship sea trials. Background Art

[0002] Wing-shaped sails achieve propulsion by utilizing the thrust component generated in the forward direction of the ship by the aerodynamic force generated by the sail under the angle of attack of the airflow. In recent years, this technology has developed rapidly, and China, Japan, the United Kingdom and other countries have successively realized the commercial operation of wing-shaped sails on large ocean-going ships. In the existing calculation method for obtaining the thrust matrix of the sail based on wind tunnel model tests, the changes in the net thrust of the sail caused by changes in the drift angle, rudder angle, etc. caused by the lateral force effect of the sail are not taken into account. Considering the objective evaluation of the EEDI contribution of the wing-shaped sail device, it is an important basis for subsequent inspections by ship inspection departments and product promotion by equipment suppliers. In view of this, the present invention proposes a method for evaluating the EEDI of wing-shaped sails based on actual ship sea trial data combined with a mathematical model of ship motion. Summary of the Invention

[0003] In response to the above problems and technical needs, the inventors proposed a method for evaluating the EEDI contribution of wing-shaped sails based on actual ship sea trials, which can provide a technical reference for the evaluation of energy-saving potential of actual routes of operating ships, classification inspection of wing-shaped sail devices, and engineering promotion.

[0004] The technical solutions of the present invention are as follows:

[0005] A method for evaluating the EEDI contribution of a wing-shaped sail based on a real ship sea trial includes the following steps:

[0006] Conduct actual ship performance tests on ships equipped with sails to obtain the main engine power required to maintain the target speed when the sails are in different operating states at various relative wind angles;

[0007] obtaining a sail net thrust test coefficient at each relative wind direction angle at a target speed based on the main engine power;

[0008] Based on the ship's four-degree-of-freedom motion model, the sail net thrust simulation coefficient curve at each relative wind direction angle at the target speed is obtained;

[0009] Comparing the sail net thrust simulation coefficient curve with the sail net thrust test coefficient, and establishing a revised four-degree-of-freedom motion model of the ship in the sail-raising operation state;

[0010] Based on the four-degree-of-freedom motion model of the ship in the sail-raising operation state and the four-degree-of-freedom motion model of the ship without sails, the sail thrust matrix elements and the sail EEDI contribution corresponding to the reference speed and any combination of wind field conditions are calculated.

[0011] Its further technical solution is that during the actual ship performance test of the ship equipped with sails, it also includes: conducting actual ship sea trials with the sails down and against the wind to obtain the main engine power required for the ship at various speeds in still water without sails.

[0012] In order to obtain the still water fast performance of the actual ship without sails through actual ship tests with sails installed, it is necessary to process the sea trial data of the ship with sails down. First, the speed and main engine power of the ship at different propeller speeds are measured when the ship is facing the wind with sails down (the relative wind direction angle is 0°). Furthermore, in order to deduct the wind load contribution of the sails in the ship's sail-down state, the main engine power at various speeds of the ship's sail-down state is obtained based on the difference in aerodynamic forces between the ship's sail-down and sail-down states obtained from CFD or wind tunnel model tests. The power-speed sea trial curve of the ship without sails can provide support for the subsequent correction of the self-propulsion factor in the four-degree-of-freedom motion model of the ship in the sail-down state.

[0013] A further technical solution is to obtain the net thrust test coefficient of the sail at each relative wind direction angle at the target speed based on the main engine power, including:

[0014] S1. Based on the difference in aerodynamic forces between the ship's sailless and sail-down states obtained from CFD or wind tunnel model tests, combined with the main engine power measured with the sail down, the main engine power at the same target speed without sails is corrected;

[0015] S2. Calculate the power reduction caused by using the sails based on the main engine power measured with the sails raised and the corrected main engine power without the sails. Furthermore, combine this with the propulsion efficiency obtained from model tests or numerical calculations at that speed to calculate the net thrust of the sail at that relative wind direction angle.

[0016] S3. The net thrust is dimensionless, the relative wind speed is taken as the value at the center height of the sail (corrected by the 1 / 9 exponential law), and the air density is obtained by looking up the table according to the measured temperature;

[0017] S4. Repeat steps S1 to S4 in the same manner, with the wind direction angle interval being 30°, to obtain the net thrust test coefficient of the sail at each relative wind direction angle.

[0018] A further technical solution is to obtain the sail net thrust simulation coefficient curve at each relative wind direction angle under the target speed based on the ship's four-degree-of-freedom motion model, including:

[0019] S1. Based on the obtained results of the ship's fast still water performance without sails, adjust the self-propulsion factor in the ship's four-degree-of-freedom motion model to match the propeller speed and main engine power corresponding to the target speed of the actual ship without sails;

[0020] S2. According to the absolute wind speed and absolute wind direction of the sea trial with sails down, the propeller thrust corresponding to the no-sail speed of the sea trial is simulated based on the ship's four-degree-of-freedom motion model with the self-propulsion factor corrected;

[0021] S3. Fit the sail aerodynamic curves obtained from wind tunnel model tests or verified numerical methods, and combine them with the four-degree-of-freedom motion model of a sailless ship to complete the straight-line motion simulation of various sail-raising operating states under the same speed conditions to obtain the propeller thrust at various relative wind direction angles;

[0022] S4. Compare the propeller thrust differences between the no-sail and raised sail states at various wind direction angles obtained by simulation to obtain the net thrust of the sail, and perform dimensionless analysis to obtain the net thrust simulation coefficient of the sail simulated by the mathematical model.

[0023] The further technical solution is to compare the sail net thrust simulation coefficient curve with the sail net thrust test coefficient to establish a revised four-degree-of-freedom motion model of the ship in the sail-raising operation state, including:

[0024] The net thrust coefficient of the sail simulated by the mathematical model is compared with the net thrust test coefficient of the sail under various relative wind direction angles in the sea trial to obtain the proportional correction factor related to the wind direction angle. The proportional correction factor is fitted (the fitting expression can be polynomial fitting, sine function sum fitting, etc.), and multiplied with the longitudinal force fitting formula of the sail aerodynamic curve in S3. Then, combined with the longitudinal force coefficient fitting expression built on the hull, the corrected four-degree-of-freedom motion model of the ship in the sail-raising operation state is established.

[0025] A further technical solution is to calculate the sail thrust matrix elements and sail EEDI contribution corresponding to the reference speed and any combination of wind field conditions, including:

[0026] S1, based on the four-degree-of-freedom motion model of the sailless ship corrected by the self-propulsion factor, and the four-degree-of-freedom motion model of the ship in the sail-raising operation state corrected by the sail longitudinal force coefficient, complete the propeller thrust calculation for the reference speed / arbitrary wind field condition combination. The difference between the two is the sail thrust matrix element corresponding to the simulated wind field condition;

[0027] S2. Combine the wind field probability distribution matrix of the world's major shipping routes with the sail thrust matrix elements to complete the evaluation of the sail EEDI contribution at any reference speed.

[0028] The beneficial technical effects of the present invention are:

[0029] Compared to the currently implemented MEPC.1 / Circ.896 document, the method described in this invention can guide the implementation of the propulsion performance sea trial of a full-scale ship equipped with a wing-shaped sail, and evaluate the net thrust matrix and EEDI contribution of the wing-shaped sail under the reference speed / arbitrary wind field condition combination. It is objective, realistic, transparent, and operational. This is mainly supported by the following two theoretical and technical aspects of fluid dynamics:

[0030] 1) By comparing the net thrust test coefficients of the sail at various relative wind angles obtained from the actual ship sea trial with the net thrust simulation coefficient curves of the sail obtained based on the ship's four-degree-of-freedom motion model, the longitudinal aerodynamic coefficients of the sail obtained based on wind tunnel model tests or verified numerical methods were corrected, thus eliminating the influence of the Reynolds number difference to a certain extent;

[0031] 2) The four-degree-of-freedom motion model used to evaluate the sail's EEDI contribution was corrected by the self-propulsion factor and verified under typical sea trial conditions. The effects of the ship's attitude angle (drift angle, heel angle, rudder angle, etc.) and propulsion efficiency on the sail's net thrust at different speeds were also taken into account.

[0032] From the above demonstration and explanation, it can be seen that the present invention takes into account the influence of Reynolds number differences, and takes into account the influence of hull attitude angle, propulsion efficiency, etc. on the net thrust of the sail. It can truly and transparently reflect the net thrust characteristics of the airfoil sail and its EEDI contribution under the combination of reference speed / arbitrary wind field conditions, and has good engineering application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a flow chart of the method for evaluating the EEDI contribution of a wing-shaped sail based on a real ship sea trial provided by this application.

[0034] Figure 2 This is a flow chart of the method for obtaining the net thrust test coefficient of the sail at various relative wind direction angles at the target speed through actual ship sea trials provided by this application.

[0035] Figure 3 This is the power P-speed V sea trial curve with and without sails under typical relative wind direction angles provided by this application.

[0036] Figure 4 This is a schematic diagram of the test coefficient of the net thrust of the sail at different relative wind direction angles provided by this application.

[0037] Figure 5 This application provides a flow chart of the sail net thrust simulation coefficient and correction method for obtaining the sail net thrust coefficient at each relative wind direction angle at the target speed based on the ship's four-degree-of-freedom motion model.

[0038] Figure 6 This is a schematic diagram of the sail longitudinal aerodynamic force (thrust) coefficient curve corrected based on actual ship sea trial data provided by this application. DETAILED DESCRIPTION

[0039] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0040] refer to Figure 1 As shown, an embodiment of the present application provides a method for evaluating the EEDI contribution of a wing-shaped sail based on a real ship sea trial, which specifically includes the following steps:

[0041] Step 1: Conduct actual ship performance tests on ships equipped with sails to obtain the main engine power required to maintain the target speed when the sails are in different operating states at various relative wind angles. To achieve a better propulsion effect, sea trials of sailboat performance generally require good wind field test conditions. Generally speaking, sails are mostly used on low-speed ships, and the average operating speed of such ships is generally between 10kn and 12kn. Therefore, in order to cover the entire absolute wind direction angle range of the sea trial and ensure that the sails can generate appropriate thrust, the absolute wind speed in the geodetic system should be higher than the average operating speed of the ship, preferably between 8m / s and 14m / s (corresponding to Beaufort 5-6).

[0042] First, adjust the ship to sail at a speed V at different propeller speeds when the relative wind direction angle is 0° (headwind), and measure the main engine power P required by the ship in still water when the sail is in the state of sail down. withsails Furthermore, in order to deduct the contribution of wind load of the sails when the ship is in the sail-down state, the main engine power P required by the ship in still water is required. withsails Correction is made to obtain the main engine power P of the ship without sails at each speed V nosails The correction method specifically includes: based on the existing CFD or wind tunnel model test, the aerodynamic force X of the ship without sails nosails and the aerodynamic force X in the sail-dropping operation state withsails Difference, and propulsion efficiency η corresponding to speed V D , calculate the main engine power P of the ship without sails at this speed nosails for:

[0043] P nosails = P withsails -(X withsails -X nosails )·V / η D (1)

[0044] Among them, the propulsion efficiency η corresponding to the speed V D Obtained from wind tunnel model tests or verified numerical methods (CFD); X nosails and X withsails The coefficient C is also obtained from CFD or wind tunnel model tests Xwithsails 、C Xnosails The forecast is obtained, expressed as:

[0045] X withsails =C Xwithsails *0.5ρ1U A 2 L 2

[0046] X nosails =C Xnosails *0.5ρ1U A 2 L 2

[0047] Where ρ1 represents the air density; U A Indicates the relative wind speed at the center height of the sail; L is the actual length of the ship.

[0048] Corrected power P of the ship without sails nosails -The speed V sea trial curve can provide support for the subsequent correction of the self-propulsion factor in the four-degree-of-freedom motion model of the ship when it is in the sailless state.

[0049] Then, with the sails retracted (sails at zero position), adjust the propeller speed so that the ship reaches the target speed (not greater than the reference speed assessed by EEDI); manipulate the rudder angle to adjust the ship's heading and steer the heading so that the ship's relative wind angle is 30°, and record the main engine power P required to maintain this speed with the sails fully retracted. 30-nosails ,like Figure 3 The hollow dot "□" on the dotted line is marked with a measurement time of 10 to 15 minutes. Adjust the sail to the state of sail raising, adjust the sail angle of attack to the optimal sail angle of attack, and control the rudder angle so that the relative wind direction angle encountered by the ship is 30 degrees. On this basis, since the sail assist provides partial thrust, adjust the propeller speed to ensure that the ship's speed is consistent with the aforementioned sail retracting state, and record the main engine power P required to maintain the target speed in this state. 30-withsails ,like Figure 3 The solid dotted line "●" is marked with a dotted line. The absolute wind speed monitored at the ship's anemometer installation height is simultaneously recorded (anemometers installed on actual ships generally allow for flexible switching between absolute and relative wind speeds). The recording time is 10 to 15 minutes. Furthermore, to save time and expense during sea trials, the main engine power is measured at each relative wind angle during the ship's performance test in the order of sail retracting, raising, and retracting.

[0050] Step 2: Based on the main engine power, obtain the net thrust test coefficient of the sail at each relative wind direction angle at the target speed. Figure 2 As shown, it specifically includes: firstly, the main engine power P measured when the sail is retracted to maintain the target speed 30-nosails Correction is made to obtain the main engine power P of the ship without sails at the same target speed 30-nosails-correctedThe correction method specifically includes: the aerodynamic force X of the ship without sails obtained based on CFD or wind tunnel model test nosails and the aerodynamic force X in the sail-dropping operation state withsails Difference, and propulsion efficiency η corresponding to speed V D , calculate the main engine power P of the ship without sails at this speed 30-nosails-corrected , the calculation formula is shown in formula (1), the corrected P 30-nosails-corrected See Figure 3 The solid dot “■” on the solid line is marked.

[0051] Then compare the main engine power when the sail is raised and when the ship has no sail at the same speed. The difference between the two is the power contribution of the airfoil sail at a relative wind direction angle of 30° ΔP1=P 30-nosails-corrected -P 30-withsails (the power reduction caused by the use of the sail), combined with the propulsion efficiency η corresponding to the target speed V D , the net thrust F of the sail when the relative wind direction angle is 30° is obtained s , F s =ΔP1·η D / V. The final net thrust F on the sail s Perform dimensionless processing to obtain the net thrust test coefficient of the sail at a relative wind direction angle of 30°

[0052]

[0053] Where: S represents the sail area; the relative wind speed at the height of the sail center is U A , which can be obtained by converting the absolute wind speed monitored at the installation height of the ship anemometer, specifically including: converting the absolute wind speed U monitored at the installation height h1 of the ship anemometer h , converted into the absolute wind speed U at the sail center height z according to the atmospheric wind profile z , U z =U h (z / h1) α , where α is the wind profile index, which can be taken as 1 / 9. According to the target speed V, the absolute wind speed U at the height of the sail center z 、Current relative wind direction angle ψ, calculate the relative wind speed U at the center height of the sail A , U A =[V 2 +U z 2 -2V·U z ·cos(π-ψ)] 1 / 2 .

[0054] Similarly, in step 1, during the sea trial, adjust the relative wind direction angle interval to 30°, repeat the calculation process in step 2, and obtain the net thrust test coefficient of the sail under each relative wind direction angle, such as Figure 4 shown.

[0055] Step 3: Based on the ship's four-degree-of-freedom motion model, obtain the sail net thrust simulation coefficient curve at each relative wind direction angle at the target speed. The ship's four-degree-of-freedom motion model uses the MMG (Maneuvering Model Group) model. For the stable straight-line state of a sail-assisted ship, the expression is as follows:

[0056] ∑X=X H +X P +X R +X a +X w =0 (3)

[0057] ∑Y=Y H +Y R +Y a +Y w =0 (4)

[0058] ∑K=K H +K R +K a +K w +m·g·h·sinφ=0 (5)

[0059] ∑N=N H +N R +N a +N w =0 (6)

[0060] Where X, Y, K, and N are the fitting equations for the longitudinal force, transverse force, heeling moment, and yaw moment, respectively. The hull hydrodynamic force, propeller hydrodynamic force, rudder hydrodynamic force, hull structure / sail aerodynamic force (when the ship is sailless, this term only includes the hull structure coefficient; when sails are added, this term includes the hull structure and sail aerodynamic coefficients), and wave drift force are marked with the subscripts "H," "P," "R," "a," and "w," respectively. m is the displacement, g is the acceleration due to gravity, h is the transverse metacentric height, and φ is the heel angle. The propeller power requirements and hull structure / sail aerodynamic force coefficients at different straight-line speeds can be predicted from rapidity tank and wind tunnel model tests. The hydrodynamic coefficients of the hull, propeller, and rudder, as well as their mutual interference factors, can be obtained based on empirical formulas. The wave drift force below the hull waterplane can be numerically calculated using the potential flow calculation software AQWA.

[0061] During stable direct sailing, the fixed speed sailing meets the following requirements:

[0062] V 2 =u2 +v 2 (7)

[0063] Based on equations (3) to (7), the motion parameters of a sailboat with or without a sail can be obtained, including the longitudinal velocity u, the transverse velocity v, the propeller speed n, the heel angle φ, and the rudder angle δ. Therefore, the propeller thrust and its received power are calculated as follows:

[0064] T=ρ2n 2 D 4 k T (J) (8)

[0065] P T =T·V·(1-w p0 ) (9)

[0066] P db =P T / η0(J) / η R (10)

[0067] Where ρ2 and D are the seawater density and propeller diameter respectively; w p0 、k T , J, η0, η R are wake fraction, propeller open water thrust coefficient, advance coefficient, open water efficiency and relative rotation efficiency; T, P T and P db They are propeller thrust, thrust horsepower and received power respectively.

[0068] According to the above model, by simulating and calculating the straight sail motion without sail and with sail raised, the net thrust simulation coefficient of the airfoil sail at each relative wind direction angle can be obtained. Figure 5 As shown, the implementation steps include: first, based on the actual ship performance test data, the ship's four-degree-of-freedom motion model is corrected to obtain the four-degree-of-freedom motion model of the ship without sails, that is, the power P of the ship without sails obtained in step 1 nosails -Speed ​​V sea trial curve is used to correct the propeller hydrodynamic term X under the longitudinal force degree of freedom formula (3) in the initial ship four-degree-of-freedom motion model P The self-propulsion factor in is used to match the propeller speed and main engine power corresponding to each speed when the ship has no sails, and the ship's four-degree-of-freedom motion model with the corrected self-propulsion factor is used as the four-degree-of-freedom motion model of the ship without sails.

[0069] Then, based on the propeller speed, absolute wind speed, and absolute wind direction of the sea trial in the sail-down state, a simulation of the ship's direct sailing motion without sails is performed at the target speed. Combined with the four-degree-of-freedom motion model of the sail-down ship, equations (3) to (8), the propeller thrust T1 at each relative wind direction angle when the ship is without sails is obtained. The sail-down aerodynamic terms in the four-degree-of-freedom motion model of the sail-down ship are updated to the hull structure and sail aerodynamic terms (i.e., the terms with subscript "a" in equations (3) to (6) are updated). A simulation of the direct sailing motion in the sail-up state is performed at the same target speed. According to the updated equations (3) to (8), the propeller thrust T2 at each relative wind direction angle in the sail-up state is obtained. The hull structure and sail aerodynamic terms can be obtained by fitting the hull structure and sail aerodynamic curves obtained by wind tunnel model tests or verified numerical methods. The fitting expression can be polynomial fitting, sine function sum fitting, etc.

[0070] Secondly, the propeller thrust of the sail-raising state and the propeller thrust of the ship without sails at the same speed are compared. The difference between the two is the net thrust of the sail at each relative wind direction angle ΔT i =T1-T2. Finally, all the net thrusts of the sails are dimensionlessly processed to obtain the net thrust simulation coefficient C of the sails at each relative wind direction angle. T , forming a sail net thrust simulation coefficient curve covering the entire wind direction angle range, such as Figure 6 Shown by the blue dotted line.

[0071]

[0072] Where: U A The relative wind speed at the center of the sail is the same as that used in the actual ship performance test.

[0073] Step 4: Compare the sail net thrust simulation coefficient curve and the sail net thrust test coefficient under each relative wind direction angle, and establish a revised four-degree-of-freedom motion model of the ship in the sail-raising operation state. Figure 5 、 Figure 6 As shown, the implementation steps include: comparing the sail net thrust test coefficient at each relative wind direction angle obtained in step 2 with the corresponding value in the sail net thrust simulation coefficient curve obtained in step 3 to obtain a proportional correction factor related to the relative wind direction angle, fitting it to obtain a proportional correction factor fitting formula, and the fitting expression form can be selected from polynomial fitting, sine function sum fitting, etc. Then, multiply the longitudinal force fitting formula of the sail aerodynamic curve obtained based on the wind tunnel model test or CFD by the proportional correction factor fitting formula to obtain Figure 6The green solid line represents the fitted equation for the longitudinal aerodynamic coefficient of the sail. Combined with the fitted equation for the longitudinal force coefficient of the hull structure, the aerodynamic terms for the hull structure and sail in the sail-raising state are constructed. Finally, the no-sail aerodynamic terms for the longitudinal force degree of freedom in the no-sail ship's four-degree-of-freedom motion model are updated with the hull structure and sail aerodynamic terms, resulting in a revised four-degree-of-freedom motion model for the entire wind direction range in the sail-raising state.

[0074] Among them, the longitudinal force fitting formula of the sail aerodynamic curve is as follows: Figure 6 The blue solid line in the middle represents the fitting formula, that is, formula (3)X a The longitudinal force on the sail, which is related to the Reynolds number, covers the entire range of wind direction angles. The longitudinal force coefficient fitting formula built on the hull is also obtained through CFD or wind tunnel model testing, covering the entire range of wind direction angles.

[0075] Step 5: Based on the four-degree-of-freedom motion model of the ship in the sail-raising operation state and the four-degree-of-freedom motion model of the ship without sails, calculate the sail thrust matrix elements and sail EEDI contribution corresponding to the reference speed and any combination of wind field conditions. Specifically, it includes: performing straight-line motion simulation of the ship in the sail-raising operation state and the sail-raising operation state at the reference speed respectively, combining the four-degree-of-freedom motion model of the ship without sails obtained in step 3 and the four-degree-of-freedom motion model of the ship in the sail-raising operation state obtained in step 4, and obtaining the propeller thrust of the ship in the sail-raising operation state and any combination of wind field conditions (absolute wind speed 0-25m / s, absolute wind direction angle 0-360°) in the sail-raising operation state respectively. Under each combination of wind field conditions, the difference between the propeller thrust of the ship in the sail-raising operation state and the propeller thrust of the ship in the sail-raising operation state is used as the element F(V ref ) k (a total of 26×72=1872 elements), where V ref is the reference speed, F is the sail thrust, and k is the kth element in the sail thrust matrix.

[0076] Combined with the wind field probability distribution matrix W of the world's major shipping routes in the MEPC.1 / Circ.896 document k , ignoring the power consumption of the airfoil sail, the available effective power provided by the sail is:

[0077]

[0078] Where, f eff ·P eff is the available effective power output by the sail, and q is the number of thrust elements corresponding to the first 1 / 2 of the wind field probability in the sail thrust matrix / wind field probability distribution matrix. k satisfy:

[0079]

[0080] Based on the available effective power provided by the sail, the expression for the sail EEDI contribution corresponding to the reference speed and any combination of wind field conditions is calculated as follows:

[0081]

[0082] Where C FME SFC is the carbon speed coefficient of the main engine fuel consumption; ME It is the unit fuel consumption related to the main engine load; Capacity is the carrying capacity.

[0083] In theory, the net thrust test coefficient of the sail is the net thrust characteristic of the sail under a specific sea trial speed and a specific test wind speed condition, including the influence of the hull attitude angle, rudder angle, etc. However, when comparing and analyzing the net thrust coefficient curves of the sail under any reference speed / wind field condition combination provided in the sea trial and the currently implemented MEPC.1 / Circ.896 document, there are still theoretical differences, including: the influence of the difference between the sea trial speed and the reference speed, the influence of the difference between the sea trial wind speed and the wind speed range statistically calculated in the probability distribution matrix of the wind field of major shipping routes in the world, and the net thrust difference caused by the two differences in the ship's navigation attitude (drift angle, heel angle and rudder angle, etc.) and propulsion efficiency. In order to correct the influence of these differences, and in order to effectively evaluate the propulsion performance of the sail in the entire absolute wind speed and absolute wind direction angle range in the MEPC.1 / Circ.896 document, the present invention proposes a method for evaluating the EEDI contribution of wing-shaped sails based on actual ship sea trials based on theoretical analysis, combined with the characteristics of actual ship sea trials, and based on mathematical model correction simulation. Among them, the sea trial method provides the test process, test collection data and requirements when the wing-shaped sail on the ship is working and not working. The method described in the present invention reflects the acquisition of the net thrust matrix of the installed sail, and reflects the changes in the ship's speed and wind field combination, hull attitude angle and propulsion efficiency after the installation of the sail. It has the characteristics of objectivity, authenticity, transparency and operability, and improves the accuracy of the sail EEDI contribution evaluation for the forecast reference speed / arbitrary wind field condition combination.

[0084] The method described in the present invention can be used to guide the implementation of actual ship sea trials of the propulsion performance of wing-shaped sails installed on ships, obtain the net thrust matrix of the sails, and guide the implementation of EEDI contribution evaluation of wing-shaped sails. It can also provide technical reference for the evaluation of energy-saving potential of actual routes of operating ships, classification inspection of wing-shaped sail devices, and engineering promotion.

[0085] The above description is only a preferred embodiment of the present application, and the present invention is not limited to the above embodiment. It is understood that other improvements and variations directly derived or imagined by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included in the scope of protection of the present invention.

Claims

1. A method for evaluating the EEDI contribution of a wing-shaped sail based on a real ship sea trial, characterized in that: The method comprises: Conduct actual ship performance tests on ships equipped with sails to obtain the main engine power required to maintain the target speed when the sails are in different operating states at various relative wind angles; obtaining a sail net thrust test coefficient at each relative wind direction angle at a target speed based on the main engine power; Based on the ship's four-degree-of-freedom motion model, the sail net thrust simulation coefficient curve at each relative wind direction angle at the target speed is obtained; Comparing the sail net thrust simulation coefficient curve with the sail net thrust test coefficient, and establishing a revised four-degree-of-freedom motion model of the ship in the sail-raising operation state; Based on the four-degree-of-freedom motion model of the ship in the sail-raising operation state and the four-degree-of-freedom motion model of the ship without sails, the sail thrust matrix elements and the sail EEDI contribution corresponding to the reference speed and any combination of wind field conditions are calculated.

2. The method for evaluating EEDI contribution of a wing-shaped sail based on a real ship sea trial according to claim 1 is characterized in that: The method further comprises: The four-degree-of-freedom motion model of the ship is corrected based on actual ship performance test data to obtain the four-degree-of-freedom motion model of the sailless ship.

3. The method for evaluating EEDI contribution of a wing-shaped sail based on a real ship sea trial according to claim 1 is characterized in that: The net thrust simulation coefficient curve of the sail at each relative wind direction angle at the target speed is obtained based on the ship's four-degree-of-freedom motion model, including: Conducting a straight-line motion simulation of a ship without sails at a target speed, and combining the four-degree-of-freedom motion model of the ship without sails to obtain the propeller thrust at each relative wind direction angle when the ship is without sails; The sailless aerodynamic term in the four-degree-of-freedom motion model of the sailless ship is updated to the hull structure and sail aerodynamic term, and a straight-line motion simulation is performed in the sail-raising operation state at the same target speed to obtain the propeller thrust at each relative wind direction angle in the sail-raising operation state; Calculate the difference ΔT between the propeller thrust at each relative wind direction angle in the sail-raising state and the propeller thrust at each relative wind direction angle when the ship has no sails. i , as the net thrust of the sail at each relative wind angle; The net thrust of all sails is processed dimensionlessly to obtain the net thrust simulation coefficient C of the sail at each relative wind direction angle. T , forming a sail net thrust simulation coefficient curve covering the entire wind direction angle range; in Where: ρ1 represents the air density; S represents the sail area; U A The relative wind speed at the sail center height, which is the same as that in the actual ship performance test, is obtained by converting the absolute wind speed monitored at the installation height of the actual ship anemometer.

4. The method for evaluating EEDI contribution of a wing-shaped sail based on a real ship sea trial according to claim 1 is characterized in that: A method for obtaining a sail net thrust test coefficient at each relative wind direction angle at a target speed based on the main engine power, wherein for a selected i-th relative wind direction angle, the method comprises: Correct the main engine power measured when maintaining the target speed with the sails retracted to obtain the main engine power when the ship is without sails at the same target speed; Calculate the difference ΔP between the main engine power measured when maintaining the target speed in the sail-raising state and the main engine power when the ship has no sails i , combined with the propulsion efficiency η corresponding to the target speed V D , get the net thrust F of the sail at the i-th relative wind direction angle s , F s =ΔP i ·η D / V; The net thrust F of the sail at the i-th relative wind direction angle s Perform dimensionless processing to obtain the net thrust test coefficient of the sail at the i-th relative wind direction angle Where: ρ1 represents the air density; S represents the sail area; U A It indicates the relative wind speed at the center height of the sail, which is obtained by converting the absolute wind speed monitored at the installation height of the ship's anemometer.

5. The method for evaluating EEDI contribution of a wing-shaped sail based on a real ship sea trial according to claim 2, characterized in that: The four-degree-of-freedom motion model of the ship is corrected based on the actual ship performance test data to obtain the four-degree-of-freedom motion model of the sailless ship, including: During the actual ship performance test of the ship equipped with sails, the ship was first adjusted to sail at different speeds at a relative wind direction angle of 0°, and the main engine power required by the ship in still water with the sails in the down and up state was measured; Correcting the main engine power required by the ship in still water to obtain the main engine power of the ship without sails at various speeds; Correct the self-propulsion factor in the propeller hydrodynamic term under the longitudinal force degree of freedom in the initial ship's four-degree-of-freedom motion model to match the propeller speed and main engine power corresponding to each speed when the ship is without sails; The ship's four-degree-of-freedom motion model with corrected self-propulsion factor is used as the four-degree-of-freedom motion model of the ship without sails.

6. The method for evaluating EEDI contribution of a wing-shaped sail based on a real ship sea trial according to claim 4 or 5, characterized in that: Correction of the main engine power measured to maintain the target speed with the sails retracted is made in the same way as correction of the main engine power required for the ship in still water, including: For the host power P to be corrected x , based on CFD or wind tunnel model test, the aerodynamic force X of the ship without sails nosails and the aerodynamic force X in the sail-dropping operation state withsails Difference, and propulsion efficiency η corresponding to speed V D , the main engine power of the ship without sails at this speed is calculated to be: P=P x -(X withsails -X nosails )·V / η D ; Among them, X nosails and X withsails The coefficient C obtained from CFD or wind tunnel model tests Xwithsails 、C Xnosails The forecast is obtained, expressed as: X withsails =C Xwithsails *0.5ρ1U A 2 L 2 X nosails =C Xnosails *0.5ρ1U A 2 L 2 Where ρ1 represents the air density; U A Indicates the relative wind speed at the center height of the sail; L is the actual length of the ship.

7. The method for evaluating EEDI contribution of a wing-shaped sail based on a real ship sea trial according to claim 3 or 4, characterized in that: The relative wind speed U at the center of the sail is obtained by converting the absolute wind speed monitored at the installation height of the ship anemometer A The methods include: The absolute wind speed U monitored at the installation height h1 of the ship anemometer h , converted into the absolute wind speed U at the sail center height z according to the atmospheric wind profile z , U z =U h (z / h1) α , where α is the wind profile index; According to the target speed V, the absolute wind speed U at the height of the sail center z 、Current relative wind direction angle ψ, calculate the relative wind speed U at the center height of the sail A , U A =[V 2 +U z 2 -2V·U z ·cos(π-ψ)] 1 / 2 .

8. The method for evaluating EEDI contribution of a wing-shaped sail based on a real ship sea trial according to claim 1, characterized in that: Comparing the sail net thrust simulation coefficient curve with the sail net thrust test coefficient, a revised four-degree-of-freedom motion model of the ship in the sail-raising operation state is established, including: Comparing the sail net thrust test coefficient at each relative wind direction angle with the corresponding value in the sail net thrust simulation coefficient curve to obtain a proportional correction factor related to the relative wind direction angle; Updating the no-sail aerodynamic term under the longitudinal force degree of freedom in the four-degree-of-freedom motion model of the no-sail ship to the aerodynamic term of the hull structure and the sail, to obtain a revised four-degree-of-freedom motion model of the ship in the sail-raising operation state; The hull superstructure and sail aerodynamic items include: The longitudinal aerodynamic coefficient of the sail is obtained by multiplying a longitudinal force fitting formula of the sail aerodynamic curve obtained based on wind tunnel model testing or CFD with a proportional correction factor fitting formula, wherein the longitudinal force fitting formula of the sail aerodynamic curve is related to the wind direction angle and the Reynolds number; The longitudinal force coefficient built on the hull is obtained through CFD or wind tunnel model testing.

9. The method for evaluating EEDI contribution of a wing-shaped sail based on a real ship sea trial according to claim 1, characterized in that: Based on the four-degree-of-freedom motion model of the ship in the sail-raising operation state and the four-degree-of-freedom motion model of the ship without sails, the sail thrust matrix elements corresponding to the reference speed and any combination of wind field conditions are calculated, including: The straight-line motion simulation of the ship in the no-sail state and the sail-raising operation state at the reference speed is respectively performed, and the propeller thrust under any combination of wind field conditions in the no-sail state and the sail-raising operation state is obtained by combining the four-degree-of-freedom motion model of the ship in the no-sail state and the four-degree-of-freedom motion model of the ship in the sail-raising operation state; Under each combination of wind field conditions, the difference between the propeller thrust of the ship in the sailless state and the propeller thrust of the sail-raising operation state is used as the element in the airfoil sail thrust matrix.

10. The method for evaluating EEDI contribution of a wing-shaped sail based on a real ship sea trial according to claim 1, characterized in that: The expression for the sail EEDI contribution corresponding to the reference speed and any combination of wind field conditions is calculated as follows: Where C FME SFC is the carbon speed coefficient of the main engine fuel consumption; ME is the unit fuel consumption related to the main engine load; Capacity is the carrying capacity; V ref is the reference speed; f eff ·P eff is the available effective power output by the sail, ignoring the power consumption of the airfoil sail. The available effective power is expressed as: Where η D is the propulsion efficiency corresponding to the reference speed, F(V ref ) k is the sail thrust matrix element corresponding to the combination of the reference speed and any wind field condition, W k is the wind field probability distribution matrix of the world's major shipping routes, k is the kth element in the sail thrust matrix / wind field probability distribution matrix, and q is the number of thrust elements in the sail thrust matrix / wind field probability distribution matrix that correspond to the top 1 / 2 of the wind field probability.

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