Method for evaluating airfoil sail EEDI contribution degree based on real ship sea test

Abstract

The invention discloses a method for evaluating the EEDI contribution degree of an airfoil sail based on a real ship sea test, and relates to the technical field of ships, and the method comprises the steps: carrying out a real ship performance test on a ship additionally provided with a sail, and obtaining the main engine power needed for maintaining a target navigational speed when the sail is in different operation states at each relative wind direction angle; obtaining a net sail thrust test coefficient of each relative wind direction angle at the target navigational speed based on the host power; based on a ship four-degree-of-freedom motion model, a sail net thrust simulation coefficient curve of each relative wind direction angle at the target navigational speed is obtained; comparing the wind sail net thrust simulation coefficient curve with the wind sail net thrust test coefficient, and establishing a corrected ship four-degree-of-freedom motion model in the sail lifting operation state; based on a ship four-degree-of-freedom motion model of a sail lifting operation state and a sail-free ship four-degree-of-freedom motion model, a sail thrust matrix element and a sail EEDI contribution degree corresponding to a reference navigational speed and any wind field condition combination are obtained through calculation, and the method has the advantages of being objective, real, operable and the like.

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 a real ship sea trial. Background Art

[0002] The wing-shaped sail achieves propulsion by utilizing the thrust component generated by the aerodynamic force generated by the sail under the angle of attack of the airflow in the forward direction of the ship. 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 change in the net thrust of the sail caused by the changes in the drift angle, rudder angle, etc. caused by the lateral force effect of the sail is not considered. 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 have 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 energy-saving potential evaluation of actual routes of operating ships, classification inspection of wing-shaped sail devices, and engineering promotion.

[0004] The technical solution of the present invention is as follows:

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

[0006] Carry out 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 direction angles;

[0007] Based on the main engine power, a test coefficient of the net thrust of the sail at each relative wind direction angle at a target speed is obtained;

[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] A 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 the actual ship test with sails installed, it is necessary to process the sea trial data of the ship with sails dropped. 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 dropped (the relative wind direction angle is 0°). Furthermore, in order to deduct the wind load contribution of the sail in the state of the ship with sails dropped, the main engine power at various speeds of the ship without sails is obtained based on the difference in aerodynamic forces between the state of the ship without sails and the state of the sails dropped obtained by 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 when it is without sails.

[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 force between the ship without sails and with sails down obtained from CFD or wind tunnel model tests, combined with the main engine power measured when the sails are down, the main engine power when disembarking without sails at the same target speed is corrected;

[0015] S2. According to the main engine power measured with the sail raised and the corrected main engine power without the sail, the power reduction caused by the use of the sail is obtained, and then the net thrust of the sail under the relative wind direction angle can be obtained by combining the propulsion efficiency obtained by model test or numerical calculation under the speed;

[0016] S3. The net thrust is dimensionless, the relative wind speed is taken as the value at the center height of the sail (such as 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. Similarly, the wind direction angle interval is 30°, and steps S1 to S4 are repeated to obtain the net thrust test coefficient of the sail under 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. According to the obtained results of the still water fast performance of the ship without sails, the self-propulsion factor in the ship's four-degree-of-freedom motion model is adjusted 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 speeds and absolute wind directions of the sea trial in the sail-dropped state, based on the ship's four-degree-of-freedom motion model with the self-propulsion factor corrected, the propeller thrust corresponding to the sea trial speed without sails is simulated;

[0021] S3. Fit the sail aerodynamic curve obtained based on the wind tunnel model test or the verified numerical method, and complete the straight-line motion simulation of each sail-raising operation state under the same speed condition in combination with the four-degree-of-freedom motion model of the ship without sails, and obtain the propeller thrust under each relative wind direction angle;

[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 simulation coefficient of the net thrust of the sail simulated by the mathematical model.

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

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

[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 a sailless ship corrected by the self-propulsion factor, and the four-degree-of-freedom motion model of a ship in the sail-raising operation state corrected by the sail longitudinal force coefficient, complete the propeller thrust calculation of the reference speed / arbitrary wind field condition combination. The difference between the two is the sail thrust matrix element corresponding to the simulation calculation 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 with the currently implemented MEPC.1 / Circ.896 document, the method described in the present invention can guide the implementation of the sea trial of the propulsion performance of a real 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, which is objective, real, transparent and operable. This is mainly supported by the following two theoretical technologies in fluid dynamics:

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

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

[0032] Through the above demonstration and explanation, it can be known that the present invention takes into account the influence of Reynolds number differences, and takes into account the influence of the 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 wing-shaped sail under the combination of reference speed / arbitrary wind field conditions and its EEDI contribution, and has good engineering application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0034] Figure 2 This is a flow chart of a method for obtaining a sail net thrust test coefficient at each relative wind direction angle at a target speed through a real ship sea trial provided by the present 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 It 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 The present application provides a flow chart of a sail net thrust simulation coefficient and correction method for obtaining sail net thrust coefficients at various relative wind direction angles at a target speed based on a 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 the present application. DETAILED DESCRIPTION

[0039] The specific implementation of the present invention will be further described below in conjunction with 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 direction angles. In order to obtain a better boost effect, the sea trial of sailing performance of sailing ships generally requires good wind field test conditions. Generally speaking, sails are mostly used for 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 the sails can generate appropriate thrust, the absolute wind speed in the geodetic system should be required to be higher than the average operating speed of the ship, preferably between 8m / s and 14m / s (corresponding to Beaufort 5-6).

[0042] First, the ship is adjusted to sail at a speed V at different propeller speeds when the relative wind angle is 0° (headwind), and the main engine power P required by the ship in still water when the sail is in the state of sailing down is measured. withsails Furthermore, in order to deduct the wind load contribution 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 After correction, the main engine power P of the ship without sails at each speed V is obtained. 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 sail 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 correction of the self-propulsion factor in the four-degree-of-freedom motion model of the subsequent ship when it is without sails.

[0049] Then, with the sails retracted (sails at zero position), adjust the propeller speed to make the ship reach 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 to maintain the ship's relative wind direction angle of 30°, and record the main engine power P required to maintain the 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°. 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 retraction state, and measure the main engine power P required to maintain the target speed in this state 30-withsails ,like Figure 3 The solid dot “●” mark is marked, and the absolute wind speed monitored at the installation height of the anemometer on the actual ship is measured and recorded (the anemometer installed on the actual ship can generally realize the free switching of absolute wind and relative wind), and the measurement time is 10min to 15min. In addition, in order to save sea trial time and cost, during the actual ship performance test, the main engine power is measured and recorded at each relative wind direction angle in the order of sail retracting → raising work → retracting.

[0050] Step 2: Based on the main engine power, obtain the sail net thrust test coefficient 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 target speed is maintained under the state of sail retracting 30-nosails After correction, the main engine power P of the ship without sails at the same target speed is obtained. 30-nosails-correctedThe correction method specifically includes: based on the aerodynamic force X of the ship without sails obtained from 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 sail 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, the main engine power is compared with the main engine power when the sail is raised and ... 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° s , F s =ΔP1·η D / V. Finally, the net thrust F of the sail s Dimensionless processing is performed to obtain the net thrust test coefficient of the sail when the relative wind direction angle is 30°

[0052]

[0053] Where: S represents the sail area; the relative wind speed at the center height of the sail is U A , can be obtained by converting the absolute wind speed monitored at the installation height of the actual ship anemometer, specifically including: converting the absolute wind speed U monitored at the installation height h1 of the actual 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 center height of the sail z , the 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, the relative wind direction angle interval is adjusted to 30°, and the calculation process in step 2 is repeated to 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, and for the sail-assisted ship's stable straight-navigation state, 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] In the formula, X, Y, K, and N are the fitting formulas of 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 has no sails, this item only has the hull structure coefficient, and when the sails are added, this item includes the hull structure and sail aerodynamic force coefficients), and wave drift force are marked with subscripts "H", "P", "R", "a", and "w" respectively; m is displacement, g is gravity acceleration, h is transverse metacentric height, and φ is heel angle. The propeller power requirements and hull structure / sail aerodynamic force coefficients at different straight-line speeds can be obtained by rapid water tank model tests and wind tunnel model test predictions; the hydrodynamic coefficients of the hull, propeller, and rudder and their mutual interference factors can be obtained based on empirical formulas; the wave drift force below the hull waterplane can be numerically calculated by the potential flow calculation software AQWA.

[0061] During steady straight sailing, the fixed speed sailing meets the following conditions:

[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 lateral 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: firstly, 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, to correct the propeller hydrodynamic term X under the longitudinal force 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 is without 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, according to the propeller speed, absolute wind speed and absolute wind direction of the sea trial in the sail-dropping state, the simulation of the direct sailing motion of the ship without sails at the target speed is carried out, and the propeller thrust T1 of the ship at each relative wind direction angle when without sails is obtained by combining the four-degree-of-freedom motion model of the sail-dropping ship (3) to (8). The aerodynamic terms without sails in the four-degree-of-freedom motion model of the sail-dropping ship are updated to the aerodynamic terms of the hull structure and the sail (i.e., the terms with subscript "a" in equations (3) to (6) are updated), and the simulation of the direct sailing motion of the sail-dropping state is carried out at the same target speed, and the propeller thrust T2 of each relative wind direction angle in the sail-dropping state is obtained according to the updated equations (3) to (8). The aerodynamic terms of the hull structure and the sail can be obtained by fitting the aerodynamic curves of the hull structure and the sail obtained by wind tunnel model test or verified numerical method, and the fitting expression form can be selected from polynomial fitting, sine function sum fitting, etc.

[0070] Secondly, the propeller thrust is compared between the sail raising state and the propeller thrust when the ship is without sails at the same speed. 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 simulation coefficient C of the net thrust 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 dashed line.

[0071]

[0072] Where: U A The relative wind speed at the center height 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, obtaining the proportional correction factor related to the relative wind direction angle, fitting it to obtain the proportional correction factor fitting formula, and the fitting expression form can be selected from polynomial fitting, sine function summation 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, whose fitting formula is the longitudinal aerodynamic coefficient of the sail, is combined with the longitudinal force coefficient fitting formula of the hull structure to form the hull structure and sail aerodynamic terms in the sail-raising operation state. Finally, the sail-free aerodynamic terms under the longitudinal force degree of freedom in the four-degree-of-freedom motion model of the sail-free ship are updated to the hull structure and sail aerodynamic terms, and the revised four-degree-of-freedom motion model of the ship in the entire wind direction angle range of the sail-raising operation state is obtained.

[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 of the sail 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 tests, 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 the 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 any wind field condition combination (absolute wind speed 0-25m / s, absolute wind direction angle 0-360°) in the sail-raising operation state and 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 main 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] In the formula, 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. Refer to MEPC.1 / Circ.896 document, W k satisfy:

[0079]

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

[0081]

[0082] In the formula, 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] Theoretically, 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, a comparison and analysis of the net thrust coefficient curve 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 shows that there are still differences in theory, 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 the world's major shipping routes, and the net thrust difference caused by the two differences in the ship's navigation attitude (drift angle, heel angle, 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 real ship sea trials based on theoretical analysis, combined with the characteristics of real ship sea trials, and based on mathematical model correction simulation. Among them, the sea trial method gives 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 evaluation of the sail EEDI contribution to the forecast reference speed / arbitrary wind field condition combination.

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

[0085] The above is only a preferred embodiment of the present application, and the present invention is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated 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 protection scope 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: Carry out 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 direction angles; Based on the main engine power, a test coefficient of the net thrust of the sail at each relative wind direction angle at a target speed is obtained; 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 the 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 sail net thrust simulation coefficient curve at each relative wind direction angle under 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 of the sail-raising operation state under the same target speed is performed 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 operation state and the propeller thrust at each relative wind direction angle when the ship has no sails i , as the net sail thrust 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 air density; S represents 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, 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: The main engine power measured when the target speed is maintained with the sails retracted is corrected 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 , and the net thrust F of the sail at the i-th relative wind direction angle is obtained 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 air density; S represents 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 actual ship 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: In the process of conducting actual ship performance tests on ships equipped with sails, the ship is first adjusted to sail at different speeds when the relative wind direction angle is 0°, and the main engine power required by the ship in still water when the sails are in the state of sail-dropping operation is 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 has no 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 a sailless ship.

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: The correction for the main engine power measured to maintain the target speed with the sails retracted is made in the same way as the correction for 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 of the ship without sails X 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 height 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 actual 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 center height of the sail z , the 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: By comparing the sail net thrust simulation coefficient curve with the sail net thrust test coefficient, a modified 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; The sailless aerodynamic term under the longitudinal force degree of freedom in the four-degree-of-freedom motion model of the sailless ship is updated to the aerodynamic term of the hull structure and the sail, so as 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 a wind tunnel model test 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 tests.

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 sailless state and the sail-raising operation state under the reference speed is respectively performed, and the propeller thrust of the ship in the sailless state and the sail-raising operation state under any combination of wind field conditions is obtained by combining the four-degree-of-freedom motion model of the ship without sails 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 ship in the sail raising operation state is used as an element in the thrust matrix of the airfoil sail.

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 of the sail EEDI contribution corresponding to the reference speed and any combination of wind field conditions is calculated as follows: In the formula, 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, and 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 corresponding to the top 1 / 2 of the wind field probability.

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