Method for actual ship sea trail-based evaluation of EEDI contribution of wing sail

Abstract

The present invention relates to the technical field of ships. Disclosed is a method for actual ship sea trail-based evaluation of an EEDI contribution of a wing sail. The method comprises: carrying out an actual ship performance test on a ship equipped with a sail, to obtain the main engine power required for maintaining a target speed when the sail is in different operation states at relative wind angles; on the basis of the main engine power, obtaining sail net thrust test coefficients of the relative wind angles at the target speed; obtaining a sail net thrust simulated coefficient curve of the relative wind angles at the target speed on the basis of a ship four-degree-of-freedom motion model; comparing the sail net thrust simulated coefficient curve with the sail net thrust test coefficients, and establishing a corrected ship four-degree-of-freedom motion model in a sail-hoisted operation state; and on the basis of the ship four-degree-of-freedom motion model in the sail-hoisted operation state and a non-sail ship four-degree-of-freedom motion model, calculating sail thrust matrix elements and a sail EEDI contribution corresponding to a reference speed and any wind field condition combination. The method has the characteristics of being objective, true, operable, etc.

Description

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

[0001] This invention relates to the field of marine technology, and in particular to a method for evaluating the EEDI contribution of airfoil sails based on actual ship sea trials. Background Technology

[0002] Airfoil sails utilize the aerodynamic force generated by the sail at the angle of attack of the airflow to produce a thrust component in the direction of the ship's movement. In recent years, this technology has developed rapidly, with China, Japan, and the UK successively achieving commercial operation of airfoil sails on large ocean-going vessels. Existing methods for calculating the sail thrust matrix based on wind tunnel model tests do not consider the changes in net sail thrust caused by variations in drift angle and rudder angle due to the lateral force effect of the sail. Considering that an objective assessment of the EEDI contribution of airfoil sail devices is crucial for subsequent ship inspections and product promotion by equipment suppliers, this invention proposes a method for evaluating the EEDI of airfoil sails based on actual ship sea trial data and a mathematical model of ship motion. Summary of the Invention

[0003] In response to the above-mentioned problems and technical requirements, the inventors have proposed a method for evaluating the EEDI contribution of airfoil sails based on actual ship sea trials. This method can provide technical reference for assessing the energy-saving potential of operating ships on actual routes, class acceptance testing of airfoil 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 airfoil sails based on actual ship sea trials includes the following steps:

[0006] Conduct real-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 under various relative wind angles;

[0007] The test coefficient of net sail thrust at each relative wind direction angle at the target speed is obtained based on the main engine power.

[0008] The simulation coefficient curves of net sail thrust at each relative wind direction angle under the target speed were obtained based on the four-degree-of-freedom motion model of the ship.

[0009] By comparing the simulated coefficient curve of the net thrust of the sail with the experimental coefficient of the net thrust of the sail, a corrected four-degree-of-freedom motion model of the ship in the sail-raising operation state is established.

[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 elements of the sail thrust matrix and the sail EEDI contribution degree corresponding to the combination of reference speed and arbitrary wind field conditions are calculated.

[0011] The 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 in the wind with the sails down to obtain the main engine power required by the ship at various speeds in still water without sails.

[0012] To obtain the still-water high-speed performance of a ship without sails through full-scale ship trials with sails installed, it is necessary to process the sea trial data of the ship with sails down. First, the ship's speed and main engine power at different propeller speeds were measured when the ship was upwind (relative wind angle 0°) with sails down. Further, to deduct the wind load contribution from the sails with sails down, the main engine power at various speeds was obtained based on the aerodynamic differences between the ship's sailless and sail-down states obtained from CFD or wind tunnel model tests. The power-speed sea trial curves of the ship without sails can provide support for the subsequent correction of the self-propulsion factor in the ship's four-degree-of-freedom motion model when the ship is without sails.

[0013] A further technical solution involves obtaining the test coefficient of net sail thrust at various relative wind angles under the target speed based on the main engine power, including:

[0014] S1. Based on the aerodynamic differences between the ship's sailless and sail-lowered states obtained from CFD or wind tunnel model tests, and combined with the main engine power measured when the sails are lowered, the main engine power of the ship without sails at the same target speed is corrected to obtain the main engine power.

[0015] S2. Based on 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. Then, combined with the propulsion efficiency obtained from model tests or numerical calculations at this speed, the net thrust of the sail at this relative wind angle can be calculated.

[0016] S3. Dimensionlessly measure the net thrust, take the relative wind speed at the height of the sail center (if corrected by the 1 / 9 exponential law), and obtain the air density from a table based on the measured temperature.

[0017] S4. Similarly, with wind direction angles at 30° intervals, repeat steps S1 to S4 to obtain the test coefficient of net sail thrust at each relative wind direction angle.

[0018] A further technical solution involves obtaining simulation coefficient curves of net sail thrust at various relative wind angles under the target speed based on a four-degree-of-freedom motion model of the ship, including:

[0019] S1. Based on the obtained results of the ship's fast performance in still water 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. Based on the absolute wind speed and absolute wind direction during the sea trial with sails down, and using a four-degree-of-freedom motion model of the ship with the self-propulsion factor modified, the propeller thrust corresponding to the sailless speed during the sea trial was simulated.

[0021] S3. Based on the wind tunnel model test or the verified numerical method, the aerodynamic curve of the sail is fitted and combined with the four-degree-of-freedom motion model of the sailless ship to complete the straight motion simulation of each sail-raising operation state under the same speed condition, and obtain the propeller thrust under each relative wind direction angle.

[0022] S4. Compare the propeller thrust differences at different wind angles with and without sails obtained from the simulation to obtain the net sail thrust. Then, make it dimensionless to obtain the simulation coefficients of the net sail thrust of the mathematical model.

[0023] The further technical solution involves comparing the simulated net thrust coefficient curve of the sail with the experimental net thrust coefficient of the sail to establish a corrected four-degree-of-freedom motion model of the ship in the sail-raising operation state, including:

[0024] The simulation coefficients of the net sail thrust from the mathematical model are compared with the experimental coefficients of the net sail thrust under various relative wind angles during sea trials. The proportional correction factor related to the wind angle is obtained and fitted (the fitting expression can be polynomial fitting, sine function summation fitting, etc.). It is then multiplied with the longitudinal force fitting expression of the sail aerodynamic curve in S3, and then combined with the longitudinal force coefficient fitting expression built on the hull to establish the corrected four-degree-of-freedom motion model of the ship in the sail raising operation state.

[0025] The further technical solution involves calculating the elements of the sail thrust matrix and the sail EEDI contribution corresponding to the combination of reference speed and arbitrary wind field conditions, including:

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

[0027] S2. Combining the probability distribution matrix of wind fields along major global shipping routes with the elements of the sail thrust matrix, complete the assessment of the EEDI contribution of sails at any reference speed.

[0028] The beneficial technical effects of this invention are:

[0029] Compared to the currently implemented MEPC.1 / Circ.896 document, the method described in this invention can guide sea trials of actual ships equipped with airfoil sails, and evaluate the net thrust matrix and EEDI contribution of the airfoil sail under reference speed / arbitrary wind field conditions. It is objective, realistic, transparent, and operable. This is mainly supported by the following two theoretical and technical aspects of fluid dynamics:

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

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

[0032] As demonstrated and explained above, this invention takes into account the influence of Reynolds number differences and the effects of hull attitude angle and propulsion efficiency on the net thrust of the sail. It can reflect the net thrust characteristics of the airfoil sail and its EEDI contribution under the combination of reference speed and arbitrary wind field conditions in a true and transparent manner, and has good prospects for engineering applications. Attached Figure Description

[0033] Figure 1 is a flowchart of the method for evaluating the EEDI contribution of airfoil sails based on actual ship sea trials provided in this application.

[0034] Figure 2 is a flowchart of the method for obtaining the net sail thrust test coefficient at various relative wind angles under the target speed in a sea trial provided in this application.

[0035] Figure 3 shows the power P-speed V sea trial curves with and without sails under typical relative wind angles provided in this application.

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

[0037] Figure 5 is a flowchart of the simulation coefficients and correction method for obtaining the net sail thrust at each relative wind direction angle at the target speed based on the four-degree-of-freedom motion model of the ship, provided in this application.

[0038] Figure 6 is a schematic diagram of the longitudinal aerodynamic force (thrust) coefficient curve of the sail based on actual sea trial data provided in this application. Detailed Implementation

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

[0040] Referring to Figure 1, one embodiment of this application provides a method for evaluating the EEDI contribution of airfoil sails based on actual ship sea trials, specifically including the following steps:

[0041] Step 1: Conduct full-scale performance tests on the vessel equipped with sails to obtain the main engine power required to maintain the target speed under different operating conditions of the sails at various relative wind angles. To obtain a better propulsion effect, sea trials of sailing vessels generally require favorable wind field testing conditions. Generally, sails are more commonly used on low-speed vessels, whose average operating speed is typically between 10 knots and 12 knots. Therefore, to cover the entire absolute wind angle range of the sea trials and ensure that the sails can generate appropriate thrust, the absolute wind speed in the geostationary system should be higher than the vessel's average operating speed, preferably between 8 m / s and 14 m / s (corresponding to Beaufort scale 5-6).

[0042] First, adjust the ship's speed V at different propeller speeds when the relative wind angle is 0° (headwind), and measure the main engine power P required by the ship in still water with the sails lowered. withsails Furthermore, to deduct the wind load contribution from the sails when the ship is in a drooping sail position, the required main engine power P of the ship in still water needs to be calculated. withsails After correction, the main engine power P of the ship without sails at each speed V is obtained. nosails The specific correction methods include: using the ship's sailless aerodynamic forces X obtained from existing CFD or wind tunnel model tests. nosails Aerodynamics X during sail lowering operation withsails The difference, and the propulsion efficiency η corresponding to speed V. D The engine power P of the ship without sails at this speed was calculated. nosails For: P nosails =P withsails -(X withsails -X nosails )·V / η D (1)

[0043] Wherein, the propulsion efficiency η corresponds to the speed V. D Obtained from wind tunnel model tests or validated numerical methods (CFD); X nosails and X withsails Also based on the coefficient C obtained from CFD or wind tunnel model tests Xwithsails C Xnosails Forecast obtained, represented as: X withsails =C Xwithsails *0.5ρ1U A 2 L 2 X nosails =CXnosails *0.5ρ1U A 2 L 2

[0044] In the formula, ρ1 represents air density; U A The relative wind speed at the center of the sail is indicated; L is the actual length of the ship.

[0045] The 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 ship when it is sailless.

[0046] Then, with the sails retracted (sails at zero position), adjust the propeller speed to bring the ship to the target speed (not exceeding the reference speed assessed by EEDI); manipulate the rudder angle to adjust the ship's course and maintain the course, so that the ship's relative wind angle is 30°, and measure the main engine power P required to maintain this speed with the sails fully retracted. 30-nosails As shown in Figure 3, the hollow dot “□” on the dotted line indicates the measurement time, which is 10-15 minutes. The sails are adjusted to the hoisting position, and the sail angle of attack is adjusted to the optimal angle. The rudder angle is then controlled to ensure the relative wind angle encountered by the ship is 30°. Based on this, since the sails provide some thrust, the propeller speed is adjusted to ensure the ship's speed is consistent with the previously mentioned sail-retired state. The main engine power P required to maintain the target speed in this state is measured. 30-withsails As shown in Figure 3, marked with a solid dot “●”, the absolute wind speed monitored at the installation height of the ship's anemometer was recorded simultaneously (the ship's anemometer can generally switch freely between absolute and relative wind speeds), with a recording time of 10-15 minutes. Furthermore, to save time and costs during sea trials, the main engine power was measured at each relative wind angle in the following sequence during the ship's performance tests: sail retraction → hoisting operation → retraction.

[0047] Step 2: Obtain the test coefficient of net sail thrust at each relative wind direction angle under the target speed based on the main engine power. As shown in Figure 2, this specifically includes: first, measuring the main engine power P while maintaining the target speed with the sails retracted. 30-nosails After correction, the main engine power P of the ship without sails at the same target speed is obtained. 30-nosails-corrected The specific correction methods include: obtaining the ship's sailless aerodynamic forces X based on CFD or wind tunnel model tests. nosails Aerodynamics X during sail lowering operation withsails The difference, and the propulsion efficiency η corresponding to speed V. D The engine power P of the ship without sails at this speed was calculated. 30-nosails-corrected The calculation formula is shown in reference formula (1), and the modified P 30-nosails-correctedSee the solid dot “■” mark on the solid line in Figure 3.

[0048] Then, compare the main engine power at the same speed with and without sails. The difference between the two is the power contribution of the airfoil sail at a relative wind angle of 30°: ΔP1 = P 30-nosails-corrected -P 30-withsails (Power loss due to sail use), combined with the propulsion efficiency η corresponding to the target speed V. D The net thrust F of the sail at a relative wind angle of 30° is obtained. s F s =ΔP1·η D / V. Finally, the net thrust F of the sail s Dimensionless processing was performed to obtain the experimental coefficient of net sail thrust at a relative wind angle of 30°.

[0049] In the formula: S represents the sail area; U represents the relative wind speed at the center height of the sail. A It can be obtained by converting the absolute wind speed monitored at the installation height of the ship's anemometer, specifically including: converting the absolute wind speed U monitored at the installation height h1 of the ship's anemometer. h The absolute wind speed U at the height z of the sail center is calculated 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. Based on the target speed V and the absolute wind speed U at the height of the sail center. z 1. Calculate the relative wind speed U at the height of the sail center, given the current relative wind angle ψ. A U A =[V 2 +U z 2 -2V·U z ·cos(π-ψ)] 1 / 2 .

[0050] Similarly, during the sea trial in step 1, the relative wind direction angle interval was adjusted to 30°, and the calculation process in step 2 was repeated to obtain the test coefficient of the net thrust of the sail under each relative wind direction angle, as shown in Figure 4.

[0051] Step 3: Obtain the simulation coefficient curves of the net sail thrust at each relative wind direction angle under the target speed based on the ship's four-degree-of-freedom motion model. The ship's four-degree-of-freedom motion model adopts the MMG (Maneuvering Model Group) model, which is used for the stable straight-line state of the sail-assisted ship, and is expressed as follows: ∑X=X H +X P +X R +Xa +X w =0 (3) ∑Y=Y H +Y R +Y a +Y w =0 (4) ∑K=K H +K R +K a +K w +m·g·h·sinφ=0 (5) ∑N=N H +N R +N a +N w =0 (6)

[0052] In the formulas, X, Y, K, and N represent the fitting equations for longitudinal force, lateral force, heel moment, and yaw moment, respectively; hull hydrodynamics, propeller hydrodynamics, rudder hydrodynamics, superstructure / sail aerodynamics (this item only includes the superstructure coefficient when the ship has no sail, and includes both the superstructure and sail aerodynamic coefficients when sails are added), and wave drift force are marked with subscripts "H", "P", "R", "a", and "w", respectively; m is displacement, g is gravitational acceleration, h is transverse metacenter height, and φ is heel angle. The propeller power demand and superstructure / sail aerodynamic coefficients at different straight-line speeds can be predicted by rapid-action tank model tests and wind tunnel model tests; 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 of the hull below the waterline can be numerically calculated using the potential flow calculation software AQWA.

[0053] When sailing steadily in a straight line, at a constant speed, the following condition must be met: V 2 =u 2 +v 2 (7)

[0054] Based on equations (3) to (7), the motion parameters for stable straight sailing without sails and with sails can be obtained, including longitudinal velocity u, lateral velocity v, propeller speed n, heel angle φ, and rudder angle δ. Therefore, the propeller thrust and the power received are calculated as follows: T = ρ²n 2 D 4 k T (J) (8) P T =T·V·(1-w p0(9) P db =P T / η0(J) / η R (10)

[0055] In the formula, ρ2 and D are the seawater density and the paddle diameter, respectively; w p0 k T 、J、η0、η R These are the wake fraction, propeller open water thrust coefficient, advance coefficient, open water efficiency, and relative rotational efficiency, respectively; T, P T and P db These are propeller thrust, thrust horsepower, and received power, respectively.

[0056] Based on the above model, by simulating the straight-line motion with and without sails, the simulation coefficients of the net thrust of the airfoil sail at each relative wind angle can be obtained. Referring to Figure 5, the implementation steps include: first, correcting the ship's four-degree-of-freedom motion model based on actual ship performance test data to obtain the four-degree-of-freedom motion model of the ship without sails, i.e., based on the power P of the ship without sails obtained in step 1... nosails -The sea trial curve of speed V is used to correct the propeller hydrodynamic term X in the longitudinal force degree of freedom equation (3) of the initial four-degree-of-freedom ship motion model. P The self-propulsion factor is used to match the propeller speed and main engine power corresponding to each speed when the ship is sailless, and the four-degree-of-freedom motion model of the ship with the corrected self-propulsion factor is used as the four-degree-of-freedom motion model of the ship without sail.

[0057] Then, based on the propeller speed, absolute wind speed, and absolute wind direction during the sea trial in the sail-lowering state, a simulation of the ship's straight-line motion without sails at the target speed is performed. Combining the four-degree-of-freedom motion model of the sailless ship with equations (3) to (8), the propeller thrust T1 at each relative wind direction angle when the ship is sailless is obtained. The aerodynamic term without sails in the four-degree-of-freedom motion model of the sailless ship is updated to the aerodynamic term of the hull superstructure and sails (i.e., the subscript "a" related terms in equations (3) to (6) are updated), and a simulation of the straight-line motion in the sail-raising state is performed at the same target speed. The propeller thrust T2 at each relative wind direction angle in the sail-raising state is obtained according to the updated equations (3) to (8). The aerodynamic term of the hull superstructure and sails can be obtained by fitting the aerodynamic curves of the hull superstructure and sails obtained from wind tunnel model tests or verified numerical methods. The fitting expression can be polynomial fitting, sine function summation fitting, etc.

[0058] Secondly, compare the propeller thrust at the same speed with and without sails; the difference is the net sail thrust ΔT at each relative wind angle. i=T1-T2. Finally, dimensionless processing is performed on all sail net thrust to obtain the simulation coefficient C of sail net thrust for each relative wind direction angle. T This forms a simulation coefficient curve of the net thrust of the sail covering the entire wind direction angle range, as shown by the blue dashed line in Figure 6.

[0059] In the formula: U A The relative wind speed at the same height of the sail center as in the actual ship performance test was used.

[0060] Step 4: Compare the simulated net sail thrust coefficient curves and experimental net sail thrust coefficients at various relative wind angles to establish a corrected four-degree-of-freedom motion model of the ship in the sail-raising operation state. Referring to Figures 5 and 6, the implementation steps include: comparing the experimental net sail thrust coefficients obtained in Step 2 with the corresponding values ​​in the simulated net sail thrust coefficient curves obtained in Step 3 to obtain a proportional correction factor related to the relative wind angle. This proportional correction factor fitting formula can be obtained by fitting polynomials, sine function summation, etc. Then, multiply the longitudinal force fitting formula of the sail aerodynamic curve obtained from wind tunnel model tests or CFD with this proportional correction factor fitting formula to obtain the green solid line in Figure 6. This fitting formula represents the longitudinal aerodynamic coefficient of the sail. Combined with the longitudinal force coefficient fitting formula built into the hull, this forms the hull and sail aerodynamic terms in the sail-raising operation state. Finally, the aerodynamic term of the sailless ship under the longitudinal force degree of freedom in the four-degree-of-freedom motion model is updated to the aerodynamic term of the ship's hull and sail, resulting in the corrected four-degree-of-freedom motion model of the ship in the entire wind direction angle range during the sail-raising operation.

[0061] Among them, the longitudinal force fitting formula of the sail aerodynamic curve is shown by the blue solid line in Figure 6, namely formula (3)X a The longitudinal sail forces related to the Reynolds number cover the entire wind direction angle range. The longitudinal force coefficient fitting formula built on the hull is also obtained through CFD or wind tunnel model tests, covering the entire wind direction angle range.

[0062] Step 5: Based on the four-degree-of-freedom motion model of the ship in sail-raised and sailless states, calculate the sail thrust matrix elements and sail EEDI contribution corresponding to the reference speed and any combination of wind conditions. Specifically, this includes: performing straight-line motion simulations of the ship in sailless and sail-raised states at the reference speed; combining the four-degree-of-freedom motion model of the ship in sailless state obtained in Step 3 and the four-degree-of-freedom motion model of the ship in sail-raised state obtained in Step 4; and obtaining the propeller thrust for any combination of wind conditions (absolute wind speed 0-25 m / s, absolute wind direction angle 0-360°) in both sailless and sail-raised states. Under each wind condition combination, the difference between the calculated propeller thrust in the sailless state and the propeller thrust in the sail-raised state is used as the element F(V) in the airfoil sail thrust matrix. ref ) k (A total of 26 × 72 = 1872 elements), of which V ref For reference speed, F is the sail thrust, and k is the kth element in the sail thrust matrix.

[0063] Combining the global major shipping route wind field probability distribution matrix W 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:

[0064] In the formula, f eff ·P eff W represents the usable effective power output of the sail, and q represents 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. Refer to MEPC.1 / Circ.896 document. k satisfy:

[0065] Based on the available effective power provided by the sails, the expression for the sail EEDI contribution corresponding to the reference speed and any combination of wind field conditions is as follows:

[0066] In the formula, C FME Carbon monoxide coefficient (SFC) for the main engine's fuel consumption. ME This refers to the unit fuel consumption related to the host load; Capacity refers to the carrying capacity.

[0067] Theoretically, the sail net thrust test coefficient represents the sail net thrust characteristics under specific sea trial speeds and test wind speeds, incorporating the effects of hull attitude angles and rudder angles. However, a comparative analysis of the sail net thrust coefficient curves for arbitrary reference speed / wind field conditions provided in the currently implemented MEPC.1 / Circ.896 document reveals theoretical differences, including: the impact of differences between sea trial speeds and reference speeds; the impact of differences between sea trial wind speeds and the wind speed ranges statistically represented in the probability distribution matrix of wind fields along major global shipping routes; and the impact of these differences on net thrust due to variations in ship attitude (drift angle, heel angle, and rudder angle) and propulsion efficiency. To correct for these differences and to effectively evaluate the sail boosting performance across the entire range of absolute wind speeds and absolute wind direction angles in the MEPC.1 / Circ.896 document, this invention, based on theoretical analysis and combined with the characteristics of actual ship sea trials, proposes a method for evaluating the EEDI contribution of airfoil sails based on actual ship sea trials, using mathematical model-corrected simulations. The sea trial method provides the test procedures, test data collection, and requirements for both working and non-working airfoil sails on board. The method described in this invention reflects the acquisition of the net thrust matrix after adding sails, and reflects the impact of changes in ship speed and wind field combination, ship attitude angle, and propulsion efficiency after adding sails. It has the characteristics of objectivity, authenticity, transparency, and operability, and improves the accuracy of the sail EEDI contribution assessment for the predicted reference speed / arbitrary wind field condition combination.

[0068] The method described in this invention can guide the implementation of actual sea trials of the propulsion performance of airfoil sails installed on ships, obtain the net thrust matrix of the sails, and guide the assessment of the EEDI contribution of airfoil sails. It can also provide technical references for assessing the energy-saving potential of operating ships on actual routes, class inspection of airfoil sail devices, and engineering promotion.

[0069] The above descriptions are merely preferred embodiments of this application, and the present invention is not limited to the above embodiments. It is understood that other improvements and variations directly derived or conceived by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included within the protection scope of the present invention.

Claims

1. A method for evaluating the EEDI contribution of airfoil sails based on actual ship sea trials, characterized in that, The method includes: Conduct real-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 under various relative wind angles; The test coefficient of net sail thrust at each relative wind direction angle at the target speed is obtained based on the main engine power. The simulation coefficient curves of net sail thrust at each relative wind direction angle under the target speed were obtained based on the four-degree-of-freedom motion model of the ship. By comparing the simulated coefficient curve of the net thrust of the sail with the experimental coefficient of the net thrust of the sail, a corrected four-degree-of-freedom motion model of the ship in the sail-raising operation state is established. 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 elements of the sail thrust matrix and the sail EEDI contribution degree corresponding to the combination of reference speed and arbitrary wind field conditions are calculated.

2. The method for evaluating the EEDI contribution of airfoil sails based on actual ship sea trials according to claim 1, characterized in that, The method further includes: Based on the actual ship performance test data, the four-degree-of-freedom motion model of the ship was modified to obtain the four-degree-of-freedom motion model of the sailless ship.

3. The method for evaluating the EEDI contribution of airfoil sails based on actual ship sea trials according to claim 1, characterized in that, The simulation coefficient curves of net sail thrust at various relative wind angles at the target speed, obtained based on the ship's four-degree-of-freedom motion model, include: A simulation of the ship's straight-line motion without sails at the target speed was conducted. Based on the four-degree-of-freedom motion model of the ship without sails, the propeller thrust of the ship at each relative wind direction angle when it is without sails was obtained. The aerodynamic term of the sailless ship in the four-degree-of-freedom motion model is updated to the aerodynamic term of the hull superstructure and sail, and the straight motion simulation of the sail-raising operation state under the same target speed is carried out to obtain the propeller thrust at each relative wind direction angle under the sail-raising operation state. Calculate the difference ΔT between the propeller thrust at each relative wind angle during the sail-raising operation and the propeller thrust at each relative wind angle when the ship has no sails. i This serves as the net thrust of the sails at each relative wind angle; Dimensionless processing is performed on all sail net thrusts to obtain the simulation coefficient C of sail net thrust for each relative wind direction angle. T This forms a simulation coefficient curve of the net thrust of the sail covering the entire wind direction angle range; in In the formula: ρ1 represents air density; S represents sail area; U A The relative wind speed at the same sail center height as in the actual ship performance test was used, and the absolute wind speed was obtained by converting it from the wind speed monitored at the installation height of the anemometer on the actual ship.

4. The method for evaluating the EEDI contribution of airfoil sails based on actual ship sea trials according to claim 1, characterized in that, A method for obtaining the test coefficient of net sail thrust at each relative wind direction angle under the target speed based on the main engine power, wherein for the selected i-th relative wind direction angle, the method includes: The main engine power measured while maintaining the target speed with the sails retracted is corrected to obtain the main engine power of the ship without sails at the same target speed; Calculate the difference ΔP between the main engine power measured while maintaining the target speed with sails raised and the main engine power of the vessel without sails. i Combined with the propulsion efficiency η corresponding to the target speed V D 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; Net sail thrust F at the i-th relative wind direction angle s Dimensionless processing is performed to obtain the experimental coefficient of net sail thrust for the i-th relative wind direction angle. In the formula: ρ1 represents air density; S represents sail area; U A This represents the relative wind speed at the height of the sail's center, obtained by converting the absolute wind speed monitored at the height of the actual ship's anemometer.

5. The method for evaluating the EEDI contribution of airfoil sails based on actual ship sea trials according to claim 2, characterized in that, Based on actual ship performance test data, the four-degree-of-freedom motion model of the ship is modified 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 when the relative wind angle was 0°, and the main engine power required by the ship in still water with the sails in the lowered sail operation state was measured. The required main engine power of the vessel in still water is corrected to obtain the main engine power of the vessel without sails at various speeds. The self-propulsion factor in the propeller hydrodynamic term under the longitudinal force degree of freedom in the initial four-degree-of-freedom motion model of the ship is modified to match the propeller speed and main engine power corresponding to each speed when the ship has no sail. The four-degree-of-freedom motion model of the ship with modified self-propulsion factor is used as the four-degree-of-freedom motion model of the ship without sails.

6. The method for evaluating the EEDI contribution of airfoil sails based on actual ship sea trials according to claim 4 or 5, characterized in that, The method for correcting the main engine power measured to maintain the target speed with the sails retracted is the same as the method for correcting the main engine power required by the ship in still water, including: For the host power P to be corrected x Ship aerodynamics without sails X based on CFD or wind tunnel model tests nosails Aerodynamics X during sail lowering operation withsails The difference, and the propulsion efficiency η corresponding to speed V. D The calculated main engine power of the ship without sails at this speed is: 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 Forecast obtained, represented as: X withsails =C Xwithsails *0.5ρ1U A 2 L 2 X nosails =C Xnosails *0.5ρ1U A 2 L 2 In the formula, ρ1 represents air density; U A The relative wind speed at the center of the sail is indicated; L is the actual length of the ship.

7. The method for evaluating the EEDI contribution of airfoil sails based on actual ship sea trials according to claim 3 or 4, characterized in that, The relative wind speed U at the height of the sail center is obtained by converting the absolute wind speed monitored at the installation height of the ship's anemometer. A The methods include: The absolute wind speed U monitored at the height h1 of the ship's anemometer installation point. h The absolute wind speed U at the height z of the sail center is calculated according to the atmospheric wind profile. z U z =U h (z / h1) α , where α is the wind profile index; Based on the target speed V and the absolute wind speed U at the height of the sail center. z 1. Calculate the relative wind speed U at the height of the sail center, given the current relative wind angle ψ. A U A =[V 2 +U z 2 -2V·U z ·cos(π-ψ)] 1 / 2 .

8. The method for evaluating the EEDI contribution of airfoil sails based on actual ship sea trials according to claim 1, characterized in that, By comparing the simulated net sail thrust coefficient curve and the experimental net sail thrust coefficient, a corrected four-degree-of-freedom motion model of the ship in the sail-raising operation state is established, including: By comparing the experimental coefficients of net sail thrust at each relative wind direction angle with the corresponding values ​​in the simulation coefficient curves of net sail thrust, a proportional correction factor related to the relative wind direction angle is obtained. In the four-degree-of-freedom motion model of the sailless ship, the aerodynamic term of the longitudinal force degree of freedom is updated to the aerodynamic term of the hull and the sail, resulting in the corrected four-degree-of-freedom motion model of the ship in the sail-raising operation state. The aforementioned hull superstructure and sail aerodynamic components include: The longitudinal aerodynamic coefficient of the sail is obtained by multiplying the longitudinal force fitting formula of the sail aerodynamic curve obtained based on wind tunnel model tests or CFD with the proportional correction factor fitting formula, wherein the longitudinal force fitting formula of the sail aerodynamic curve is related to the wind direction angle and Reynolds number. The longitudinal force coefficients built on the hull are obtained through CFD or wind tunnel model tests.

9. The method for evaluating the EEDI contribution of airfoil sails based on actual ship sea trials 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 elements of the sail thrust matrix corresponding to the combination of reference speed and arbitrary wind field conditions are calculated, including: The straight-line motion simulation of the ship under reference speed in both sailless and sail-raised states was carried out. By combining the four-degree-of-freedom motion model of the ship without sail and the four-degree-of-freedom motion model of the ship under sail-raised state, the propeller thrust under any combination of wind field conditions in both states was obtained. Under each combination of wind conditions, the difference between the propeller thrust of the ship in the sailless state and the propeller thrust in the sail-raised state is used as an element in the airfoil sail thrust matrix.

10. The method for evaluating the EEDI contribution of airfoil sails based on actual ship sea trials according to claim 1, characterized in that, The expression for the sail EEDI contribution corresponding to the combination of reference speed and arbitrary wind field conditions is as follows: In the formula, C FME Carbon monoxide coefficient (SFC) for the main engine's fuel consumption. ME V represents the unit fuel consumption related to the host load; Capacity represents the carrying capacity; ref The reference speed; f eff ·P eff The available effective power output of the sail, ignoring the power consumption of the airfoil sail, is expressed as: In the formula, η D For reference propulsion efficiency corresponding to speed, F(V) ref ) k W represents the sail thrust matrix element corresponding to the combination of the reference speed and arbitrary wind field conditions. k is the probability distribution matrix of wind fields along major global shipping routes, k is the kth element in the wind thrust matrix / wind field probability distribution matrix, and q is the number of thrust elements in the wind thrust matrix / wind field probability distribution matrix corresponding to the first half of the wind field probability.

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