A method for predicting energy-saving effect of a specific route sail-assisted ship

Abstract

The application discloses a kind of specific route sail boost ship energy-saving effect prediction method, first based on sail aerodynamic force characteristics carries out optimal thrust characteristic prediction, and determines sail angle control strategy;According to the principle of standard sub voyage, determine the target route track point, consider a diffusion domain extraction the original wind field data in this area;Using 3 delta principle carries out wind field data deviation analysis and screening, and corrects wind profile, obtains effective wind power resource database;Calculate the relative wind speed and relative wind direction angle at each sample point under the ship speed, further calculate sail propulsion power;Comprehensive all sail propulsion power at all track points at all times, obtain the comprehensive energy-saving effect of target route.The method can effectively consider the square relationship between sail thrust characteristic and wind speed, without establishing wind field probability matrix, can realize the sail boost energy-saving effect prediction of any route in global range, with higher prediction accuracy, provides reliable foundation for industrial application of sail device.

Description

Technical Field

[0001] This invention belongs to the field of marine vessel design and construction, and specifically relates to a method for predicting the energy-saving effect of sail-assisted ships on specific routes. Background Technology

[0002] The propulsion effect of a sail-assisted propulsion system depends on both the wind field data of the route and the thrust characteristics of the sail. Currently, there is no standardized process or method for evaluating the thrust characteristics a single sail can provide to a ship based on its aerodynamic characteristics, thereby determining the corresponding control strategy. Furthermore, ocean wind resources are a prerequisite for ships to utilize wind energy for propulsion and energy saving when installing wind-assisted propulsion systems. To calculate the overall energy-saving effect of wind-assisted propulsion systems, the traditional approach first requires obtaining a comprehensive wind field probability matrix based on the specific wind field conditions when the ship is sailing on a particular route, using relative wind speed and relative wind direction angle intervals as statistical characteristics. Then, the sail load probability matrix is ​​calculated in conjunction with the sail thrust characteristics, the power matrix is ​​calculated considering the ship's speed, and finally, the total propulsion power is calculated by summing the probabilities. In this process, the wind speed at 10m above sea level is often directly extracted, ignoring the wind profile effect and the wind field error caused by the discreteness of the ship's navigation trajectory. In addition, in the process of statistically analyzing the wind field according to the wind speed range and wind direction angle range, the fact that the magnitude of the sail thrust is positively correlated with the square of the wind speed is ignored, which leads to a certain deviation in the final probability matrix. As a result, the propulsion power predicted is not accurate enough compared with the actual situation.

[0003] To address the problems existing in the prediction of the energy-saving effect of sail-assisted propulsion devices, this invention proposes a method for predicting the energy-saving effect of sail-assisted propulsion vessels on specific routes. Based on this method, the thrust characteristics of sail-assisted propulsion vessels can be accurately assessed, the corresponding sail angle control strategy can be determined, and the energy-saving effect prediction of sail-assisted propulsion vessels on any route worldwide can be achieved. Summary of the Invention

[0004] This invention provides a method for predicting the energy-saving effect of sail-assisted ships on specific routes, and the technical solution adopted is as follows: Step 1: Determine the aerodynamic characteristic matrix of the sail when evaluating the thrust characteristics of the sail.

[0005] Step 101: Define a sail coordinate system to characterize the wind attack angle β of the sail and the aerodynamic characteristics of a single sail, denoted as Coor.o', with the origin o' being the intersection of the width axis of the sail and the axis of symmetry.

[0006] The x-axis is along the width axis of the sail, with positive to the right.

[0007] The y-axis is perpendicular to the axis and points towards the convex surface as positive.

[0008] The z-axis is along the height of the sail, with upwards being positive.

[0009] The wind attack angle β is defined as the angle between the direction of the wind and the x-axis in the sail coordinate system. β ranges from [0°, 180°] and rotates counterclockwise around the y-axis.

[0010] Step 102: Determine the aerodynamic characteristic matrix of the sail.

[0011] The aerodynamic characteristics of the sail device are obtained based on single-sail aerodynamic analysis or model tests, and are characterized by dimensionless coefficient matrices Cn and Ct.

[0012] Cn is the normal force coefficient matrix perpendicular to the sail axis in the sail coordinate system.

[0013] Ct is the dimensionless axial force coefficient matrix along the sail axis in the sail coordinate system.

[0014] The normal force coefficient Cn and the axial force coefficient Ct vary with the wind angle of attack β. The aerodynamic matrix of the sail is expressed as follows, where the value of β ranges from [0°, 180°] and the value of the wind angle of attack interval Δβ ranges from [1°, 10°].

[0015] Step 2: Predict the thrust characteristics of the sail and determine the sail angle.

[0016] Step 201: Define the ship's coordinate system to represent the relative wind direction angle α and the sail rotation angle θ, denoted as Coor.0. The origin 0 is taken as the intersection of the ship's stern perpendicular line, the mid-longitudinal section, and the baseline.

[0017] X-axis: The longitudinal axis, with the positive direction pointing from the stern to the bow.

[0018] Y-axis: The horizontal axis, with the positive direction pointing from the ship's centerline to the port side.

[0019] Z-axis: Vertical axis, its positive direction is perpendicular to the XY plane and upwards.

[0020] The angle α between the sail and the wind direction of a ship is defined as the angle between the direction of the wind and the direction of the ship's bow. Clockwise rotation is positive, and the value of α ranges from [0° to 360°]. When the bow is directly facing the wind, α = 0°.

[0021] The sail rotation angle θ refers to the angle through which the y-axis of the sail coordinate system rotates relative to the x-axis of the ship coordinate system. Clockwise rotation is positive and counterclockwise rotation is negative. The range of θ is [-90°, +90°].

[0022] Step 202: Determine the feasible range of sail rotation angle θ for each relative wind direction angle α. liml ,θ limr This allows for the generation of thrust along the ship's length within the sail's turning angle range, thus yielding the effective sail turning angle matrix interval.

[0023] The relative wind direction angle α ranges from [0°, 360°), and the i-th relative wind direction angle is denoted as α. i .

[0024] The interval Δα between relative wind direction angles is taken as 1°, for a total of 360 relative wind direction angles. i The corresponding relative wind angle is i.

[0025] θ liml θ represents the left limit of the sail rotation angle corresponding to the relative wind angle α. limr This represents the right limit of the sail rotation angle corresponding to the relative wind direction angle.

[0026] Relative wind angle α i When ∈ [0, 180], the left limit θ limli =-90°, right limit θ limri =-90°+α i .

[0027] Relative wind angle α i When ∈(180, 360), the left limit θ limli =α i -270°, right limit θ limri =90°.

[0028] θ limli Indicates with α i The corresponding left limit of the sail rotation angle, θ limri Indicates with α i The corresponding right limit of the sail rotation angle.

[0029] Relative wind angle α i The corresponding number of feasible sail turning angles is θ limri -θ limli +1.

[0030] Step 203: For each relative wind direction angle α i Iterate through each effective sail angle and calculate the corresponding angle of attack β. newij , to obtain β new A two-parameter two-dimensional matrix.

[0031] Where, β newij This indicates the relative wind direction angle α i and its corresponding j-th relative sail rotation angle θ ij The angle of attack of the wind.

[0032] Angle of attack β newij It can be calculated by the following formula: β newij =270°+θ ij -α i .

[0033] Step 204: The calculated wind attack angle β new The wind attack angle β is obtained by interpolating a two-parameter two-dimensional matrix with the single sail aerodynamic characteristic matrices Cn and Ct respectively. new The corresponding normal force coefficient matrix Cn_new and axial force coefficient matrix Ct_new.

[0034] Relative wind angle α i Downwind angle of attack β newij The corresponding normal force coefficient matrix is ​​denoted as Cn_new ij The axial force coefficient is denoted as Ct_new ij .

[0035] The interpolation algorithm uses quadratic spline interpolation to ensure engineering accuracy.

[0036] Step 205: For each relative wind direction angle α i sail angle θ ij Based on the aerodynamic matrix of the sail obtained in step 204 above, the thrust coefficient matrix fx in the hull coordinates is further calculated.

[0037] Relative wind angle α i Downsail angle θ ij The corresponding thrust coefficient is denoted as fx ij It can be calculated using the following formula: fx ij =Cn_new ij ×cos(θ ij )-Ct_new ij ×sin(θ ij ).

[0038] Step 206: For the relative wind direction angle α i Iterate through each sail turning angle θ ij The corresponding thrust coefficient fx ij The maximum thrust coefficient f is obtained. xi The sail thrust characteristics used to characterize the sail rotation at this relative wind angle are called the sail control angle θ. controli .

[0039] By iterating through all relative wind angles, we obtain the sail thrust coefficient matrix fx and the sail rotation control matrix θ. control .

[0040] Step 3: Forecast of the energy-saving effect of sail-assisted ships on specific routes.

[0041] For specific routes, route planning and wind resource assessment are carried out, and the overall energy-saving effect of the sail is calculated by combining the sail thrust coefficient matrix obtained in step 206.

[0042] Step 301: Route planning and wind information extraction.

[0043] 1) Set the departure and arrival port positions of the target route, and divide the target route into several equal segments according to the standard sub-journey principle; the standard sub-journey is the distance the ship travels at an economical speed S. ship The distance traveled in 6 hours; for the last sub-journey, if it is less than the distance traveled by the ship in 3 hours at economic speed, it is disregarded.

[0044] Thus, the target route is divided into N-1 segments of equal distance, with the initial and final points of each segment recorded as track points. This operation generates a total of N track points. Further, the longitude Lo of each track point is obtained. i and latitude La i (i=1,2,…,N), are recorded in database A.

[0045] 2) Extract the original wind resource data under the latitude and longitude coordinates of the route over the past 10 years. When extracting wind information at the specific track point, the dispersion of the ship's motion trajectory is taken into consideration. The range of the single-sided extended domain is 0.3° x 0.3° with the track point as the center. In this way, the reference wind resource data on the target route is obtained, including "Vu0" and "Vv0" under "time", "longitude" and "latitude".

[0046] Vu0 and Vv0 are the absolute wind speeds in the east-west and north-south directions, respectively, obtained directly from the geodetic coordinate system.

[0047] The wind field data extraction precision is set to 0.125° x 0.125°, and the extraction times include 00:00, 06:00, 12:00, and 18:00. By considering wind resources in all time periods, the wind field data of the target route is not limited by the departure time of the ship's characteristic voyage, and is more general and statistical. The k-th east-west wind speed component at the i-th track point is denoted as Vu0ik, and the south-north wind speed component is denoted as Vv0ik (i=1,2,…,N; k is the total number of wind fields within the extended domain).

[0048] 3) Evaluate and screen the effective wind field data, and update the wind field data for the flight path.

[0049] For each track point, the absolute wind speed Vu0, Vv0, and composite wind speed within the extended domain at all times are calculated. Deviation analysis was performed using the 3δ principle. If any requirement was not met, the corresponding data was removed.

[0050] The wind field data obtained from the wind resource database is the average wind speed at 10 meters above sea level, which is converted into the average wind speeds Vu and Vv at Zm above sea level using the following formulas: .

[0051] .

[0052] Zm is the distance from the center of the sail height of the sail-assisted vessel to the sea level; γ is the wind profile height coefficient.

[0053] The above provides a revised database of effective wind resources for specific flight routes.

[0054] Step 302: Calculate the relative wind direction and wind speed after considering the ship's speed.

[0055] For each moment, the ship's speed S at track point i is... ship As the vector magnitude, the heading COGi is used as the vector direction, and it is vector-superimposed with the absolute wind speeds Vu0ik and Vv0ik in the effective wind resource database. The resulting vector magnitude is the relative wind speed AWS. ik The angle between the wind direction and the ship's heading is called the relative wind angle α. ik The component of a ship's speed in the east-west direction is denoted as Uship, and the component in the north-south direction is denoted as Vship.

[0056] The heading at each trackpoint is the direction of the line connecting its adjacent trackpoints, and the heading at the last trackpoint is the same as the heading at the previous trackpoint.

[0057] According to step 302, the relative wind speed and relative wind direction angle databases corresponding to all valid wind resource databases at all track points at all times can be calculated, including "time", "longitude", "latitude", "AWS" and "α"; the number of sample points in all databases is counted and denoted as M.

[0058] Step 303: Forecast of the energy-saving effect of sail-assisted ships on specific routes.

[0059] Based on the relative wind speed and relative wind direction angle database obtained in step 302, firstly, for each element m, the corresponding relative wind direction angle α is used... m Combining the interpolation from step 206 to obtain the corresponding sail thrust coefficient fxm, the sail propulsion power is then calculated using the following formula: .

[0060] In the above formula, A is the reference area of ​​the sail device, ρ is the air density, and fxm is the relative wind angle α. m The thrust coefficient of the sail under the current, AWS mLet m be the relative wind speed corresponding to the m-th element.

[0061] Considering the combined wind field conditions at all historical moments and after track points along the entire route, the calculated combined sail propulsion power is obtained by the following formula: .

[0062] Technical advantages: 1. In view of the complex process of forecasting the thrust characteristics of wind turbines, this invention provides a standardized process and method for evaluating the thrust characteristics of a single airfoil wind turbine with clear logic, which can predict the maximum thrust effect of a given wind turbine with certain aerodynamic characteristics on a ship.

[0063] 2. The present invention accurately identifies the factors affecting the thrust characteristics of sails. Through regression analysis, the relative wind direction angle interval is taken as 1.0° and the relative sail turning angle interval is taken as 1.0°. This enables accurate and efficient thrust characteristic prediction, meeting engineering forecasting requirements.

[0064] 3. In the process of wind field extraction along a route, the present invention directly extracts wind field data with an accuracy of 0.125° x 0.125° and considers an extended domain of 0.3° x 0.3°, so that the wind field data at a specific track point can take into account the dispersion of the actual navigation process of the ship, thereby improving the comprehensive representativeness of the wind field data.

[0065] 4. The present invention first processes the wind field data, using the 3δ principle to filter the wind field data at each track point, and further corrects the original wind field data by considering the wind profile effect at each sample point, thereby improving the accuracy of data forecasting.

[0066] 5. Starting from the essence of energy-saving effect forecasting, this invention adopts a method of directly performing comprehensive analysis and correction on all sample points and calculating the sail boost power based on a single sample point. This method can directly consider the square relationship between sail thrust and propulsion power and the square of wind speed, avoiding the error caused by using the first power of wind speed in the traditional method due to considering the wind field probability matrix regression, thus improving the accuracy of energy-saving effect forecasting.

[0067] The method of this invention can reliably predict the energy-saving effect of sail-assisted propulsion on any global route, providing a reliable foundation for the industrial application of sail devices. Attached Figure Description

[0068] Figure 1 This is a diagram illustrating the definition of the sail coordinate system and the angle of attack.

[0069] Figure 2 This is a diagram illustrating the definition of the ship's coordinate system and the angle of the sail.

[0070] Figure 3 This is a schematic diagram showing the breakdown of ship speed and the calculation of relative wind speed and direction.

[0071] Figure 4 It is a heading diagram corresponding to N waypoints. Detailed Implementation

[0072] The invention will be further described with reference to the accompanying drawings.

[0073] A method for predicting the energy-saving effect of sail-assisted ships on specific routes, the specific operation of which is as follows: Step 1: Determine the aerodynamic characteristic matrix of the sail when evaluating the thrust characteristics of the sail.

[0074] Step 101: Define a sail coordinate system to characterize the wind attack angle β of the sail and the aerodynamic characteristics of a single sail, denoted as Coor.o'.

[0075] Origin o': is the intersection of the axis of the sail width direction and the axis of symmetry.

[0076] The x-axis is along the width axis of the sail, with positive to the right.

[0077] The y-axis is perpendicular to the axis and points towards the convex surface as positive.

[0078] The z-axis is along the height of the sail, with upwards being positive.

[0079] The wind attack angle β is defined as the angle between the direction of the wind and the x-axis in the sail coordinate system; β ranges from [0°, 180°], rotating counterclockwise around the y-axis, as shown below. Figure 1 As shown.

[0080] Step 102: Determine the aerodynamic characteristic matrix of the sail.

[0081] The aerodynamic characteristics of the sail device are obtained based on single-sail aerodynamic analysis or model tests, and are characterized by dimensionless coefficient matrices Cn and Ct.

[0082] Cn is the normal force coefficient matrix perpendicular to the sail axis in the sail coordinate system.

[0083] Ct is the dimensionless axial force coefficient matrix along the sail axis in the sail coordinate system.

[0084] The normal force coefficient Cn and the axial force coefficient Ct vary with the wind angle of attack β. The aerodynamic matrix of the sail is expressed as follows, where the value of β ranges from [0°, 180°] and the value of the wind angle of attack interval Δβ ranges from [1°, 10°].

[0085] In this embodiment, the normal force coefficient matrix Cn and the axial force coefficient matrix Ct under various wind attack angles are obtained through numerical analysis. The wind attack angle interval Δβ is taken as 10°. The aerodynamic characteristic matrix of the sail is shown in the table below:

[0086] Step 2: Predict the thrust characteristics of the sail and determine the sail angle.

[0087] Step 201: Define the ship's coordinate system to represent the relative wind direction angle α and sail rotation angle θ, denoted as Coor.o, such as... Figure 2 As shown.

[0088] Origin 0: is the point where the ship's stern perpendicular, mid-longitudinal section and baseline intersect; X-axis: The longitudinal axis, with the positive direction pointing from the stern to the bow.

[0089] Y-axis: The horizontal axis, with the positive direction pointing from the ship's centerline to the port side.

[0090] Z-axis: Vertical axis, its positive direction is perpendicular to the XY plane and upwards.

[0091] The relative wind angle α of a sail-assisted ship is defined as the angle between the direction of the wind and the direction of the ship's bow. Clockwise rotation is positive, and the value of α ranges from [0°, 360°]. When the bow is directly facing the wind, α = 0°.

[0092] The sail rotation angle θ refers to the angle through which the y-axis of the sail coordinate system rotates relative to the x-axis of the ship coordinate system. Clockwise rotation is positive and counterclockwise rotation is negative. The range of θ is [-90°, +90°].

[0093] Step 202: Determine the feasible range of sail rotation angle θ for each relative wind direction angle α. liml ,θ limr This allows for the generation of thrust along the ship's length within the sail's turning angle range, thus yielding the effective sail turning angle matrix interval.

[0094] The relative wind direction angle α ranges from [0 to 1]. The i-th relative wind direction angle is denoted as α. i .

[0095] The interval Δα between relative wind direction angles is taken as 1°, for a total of 360 relative wind direction angles; α i The corresponding relative wind angle is i.

[0096] θ liml θ represents the left limit of the sail rotation angle corresponding to the relative wind angle α. limr This represents the right limit of the sail rotation angle corresponding to the relative wind direction angle.

[0097] Relative wind angle α i When ∈ [0, 180], the left limit θ limli =-90°, right limit θ limri =-90°+αi .

[0098] Relative wind angle α i When ∈(180, 360), the left limit θ limli =α i -270°, right limit θ limri =90°.

[0099] θ limli Indicates with α i The corresponding left limit of the sail rotation angle, θ limri Indicates with α i The corresponding right limit of the sail rotation angle.

[0100] In this embodiment, to more concisely and clearly illustrate the entire calculation process, the relative wind direction angle interval Δα is taken as 10°, and the sail turning angle interval Δθ is taken as 10°. ij Taking 10° as the value, we obtain the effective sail angle limit matrix and the effective sail angle matrix. The effective sail angle limit matrix is ​​shown in the table below:

[0101] The effective sail angle matrix is ​​shown in the table below:

[0102] Step 203: For each relative wind direction angle α i Iterate through each effective sail angle and calculate the corresponding angle of attack β. newij , to obtain β new A two-parameter two-dimensional matrix.

[0103] β newij This indicates the relative wind angle α i and its corresponding j-th relative sail rotation angle θ ij The angle of attack of the wind.

[0104] Angle of attack β newij It can be calculated by the following formula: β newij =270°+θ ij -α i .

[0105] Based on the aforementioned formula, the wind attack angle β calculated in this embodiment new The matrix is ​​shown in the table below:

[0106] Step 204: Calculate the wind attack angle β new The wind attack angle β is obtained by interpolating a two-parameter two-dimensional matrix with the single sail aerodynamic characteristic matrices Cn and Ct respectively. newThe corresponding normal force coefficient matrix Cn_new and axial force coefficient matrix Ct_new.

[0107] Relative wind angle α i Downwind angle of attack β newij The corresponding normal force coefficient matrix is ​​denoted as Cn_new ij The axial force coefficient is denoted as Ct_new ij .

[0108] The interpolation algorithm uses quadratic spline interpolation to ensure engineering accuracy.

[0109] In this embodiment, the calculated Cn_new matrix is ​​shown in the table below:

[0110] In this embodiment, the calculated Ct_new matrix is ​​shown in the table below:

[0111] Step 205: For each relative wind direction angle α i sail angle θ ij Based on the aerodynamic matrix of the sail obtained in step 204 above, the thrust coefficient matrix fx in the hull coordinates is further calculated, relative to the wind direction angle α. i Downsail angle θ ij The corresponding thrust coefficient is denoted as fx ij It can be calculated using the following formula: fx ij =Cn_new ij ×cos(θ ij )-Ct_new ij ×sin(θ ij ).

[0112] In this embodiment, the calculated thrust coefficient matrix is ​​shown in the table below:

[0113] Step 206: For the relative wind direction angle α i Iterate through each sail turning angle θ ij The corresponding thrust coefficient fx ij The maximum thrust coefficient f is obtained. xi The sail thrust characteristics used to characterize the sail rotation at this relative wind angle are called the sail control angle θ. controli .

[0114] By iterating through all relative wind angles, we obtain the sail thrust coefficient matrix fx and the sail rotation control matrix θ. control .

[0115] The final sail thrust coefficient matrix fx and sail angle control matrix θ obtained in this embodiment control As shown in the table below:

[0116] The calculation results of this embodiment show that the sail cannot generate thrust between [0°, -20°] and (340°, -360°]. When the wind is coming from within this relative wind angle range, the sail needs to be set to a sheltered position to reduce the resistance to the ship. Correspondingly, the thrust coefficient is 0 in this range.

[0117] Step 3: Forecast of the energy-saving effect of sail-assisted ships on specific routes.

[0118] For specific routes, route planning and wind resource assessment are carried out, and the overall energy-saving effect of the sail is calculated by combining the sail thrust coefficient matrix obtained in step 206.

[0119] Step 301: Route planning and wind information extraction.

[0120] 1) Set the departure and arrival port positions of the target route, and divide the target route into several equal segments according to the standard sub-journey principle; the standard sub-journey is the distance the ship travels at an economical speed S. ship The distance traveled in 6 hours; for the last sub-journey, if it is less than the distance traveled by the ship in 3 hours at economic speed, it is disregarded.

[0121] Thus, the target route is divided into N-1 segments of equal distance, with the initial and final points of each segment recorded as track points. This operation generates a total of N track points. Further, the longitude Lo of each track point is obtained. i and latitude La i (i=1,2,…,N), are recorded in database A.

[0122] In this embodiment, a typical route frequently operated by a 210,000-ton bulk carrier is used as an example for route planning, with the ports being Qingdao Port and Port Hedland. The Marine traffic.com website is used for route planning, outputting the latitude and longitude information of each point on the route. In this embodiment, the round-trip voyage is the same, 3500 nautical miles. The ship, fully loaded, departs from Hedland to Qingdao at a speed of 10.5 knots, with a standard sub-voyage of 63 nautical miles. Therefore, the full-load voyage divides the entire route into 56 segments, totaling 57 trackpoints, as shown in the table below:

[0123]

[0124] 2) Extract the original wind resource data under the latitude and longitude coordinates of the route over the past 10 years. When extracting wind information at the specific track point, the dispersion of the ship's motion trajectory is taken into consideration. The range of the single-sided extended domain is 0.3°×0.3° with the track point as the center. In this way, the reference wind resource data on the target route is obtained, including "Vu0" and "Vv0" under "time", "longitude" and "latitude".

[0125] Vu0 and Vv0 are the east-west and north-south absolute wind speeds obtained directly in the geodetic coordinate system, respectively. The original wind field information at a certain moment is shown in the table below.

[0126] The wind field data extraction precision is set to 0.125°×0.125°, and the extraction times include 00:00, 06:00, 12:00, and 18:00. By considering wind resources in all time periods, the wind field data of the target route is not limited by the departure time of the ship's characteristic voyage, and is more general and statistical. The k-th east-west wind speed component at the i-th track point is denoted as Vu0ik, and the south-north wind speed component is denoted as Vv0ik (i=1,2,…,N; k is the total number of wind fields within the extended domain).

[0127]

[0128] 3) Evaluate and screen the effective wind field data, and update the wind field data for the flight routes.

[0129] For each track point, the absolute wind speed Vu0, Vv0, and composite wind speed within the extended domain at all times are calculated. Deviation analysis was performed using the 3δ principle. If any requirement was not met, the corresponding data was removed.

[0130] The wind field data obtained from the wind resource database is the average wind speed at 10 meters above sea level, which is converted into the average wind speeds Vu and Vv at Zm above sea level using the following formulas: .

[0131] .

[0132] Zm is the distance from the center of the sail height of a sail-assisted vessel to the sea level; γ is the wind profile height coefficient; the above is used to obtain the corrected effective wind resource database for a specific route.

[0133] In this embodiment, the distance from the center of the sail height to the sea level is 25.2m, and the wind profile coefficient γ is taken as 8 according to the CCS classification society sail guidelines. Therefore, for all raw wind field data, a wind profile correction factor needs to be used. =1.122.

[0134] Step 302: Calculate the relative wind direction and wind speed after considering the ship's speed.

[0135] For each moment, the ship speed Sship at track point i is taken as the vector magnitude, and the heading COGi is taken as the vector direction. These are then vector-superimposed with the absolute wind speeds Vu0ik and Vv0ik in the effective wind resource database. The resulting vector magnitude is the relative wind speed AWS. ik The angle between the wind direction and the ship's heading is the relative wind angle α. ik The component of a ship's speed in the east-west direction is denoted as Uship, and the component in the north-south direction is denoted as Vship; for example... Figure 4 As shown.

[0136] The heading at each waypoint is the direction of the line connecting its adjacent waypoints, and the heading at the last waypoint is the same as the heading at the previous waypoint. Figure 4 As shown.

[0137] According to step 302, the relative wind speed and relative wind direction angle databases corresponding to all valid wind resource databases at all track points at all times can be calculated, including "time", "longitude", "latitude", "AWS" and "α"; the number of sample points in all databases is counted and denoted as M. In this implementation example, the total number of sample points is 10,818,102.

[0138] Step 303: Forecast of the energy-saving effect of sail-assisted ships on specific routes.

[0139] Based on the relative wind speed and relative wind direction angle database obtained in step 302, firstly, for each element m, the corresponding relative wind direction angle α is used... m Combining the interpolation from step 206 to obtain the corresponding sail thrust coefficient fxm, the sail propulsion power is then calculated using the following formula: .

[0140] In the above formula, A is the reference area of ​​the sail device, ρ is the air density, and fxm is the relative wind angle α. m The thrust coefficient of the sail under the current, AWS m Let m be the relative wind speed corresponding to the m-th element.

[0141] In this embodiment, the reference area of ​​the sail device is s=280m². 2 The air density ρ = 1.225 kg / m³ 3 The sail thrust coefficients obtained by interpolation using various relative wind angles A and the thrust coefficient matrix f are shown in the table below (showing some results):

[0142] Considering the combined wind field conditions at all historical moments and after track points along the entire route, the calculated combined sail propulsion power is obtained by the following formula: .

Claims

1. A method for predicting the energy-saving effect of sail-assisted ships on specific routes, characterized in that, The specific steps are as follows: Step 1: Determine the aerodynamic characteristic matrix of the sail when evaluating its thrust characteristics; Step 101: Define a sail coordinate system to characterize the wind attack angle β of the sail and the aerodynamic characteristics of a single sail, denoted as Coor.o', with the origin o' being the intersection of the width axis of the sail and the axis of symmetry. The x-axis is along the width axis of the sail, with positive to the right; The y-axis, perpendicular to the axis, points towards the convex surface and is positive; The z-axis, along the direction of the sail height, is positive upwards; The wind attack angle β is defined as the angle between the direction of the wind and the x-axis in the sail coordinate system; β ranges from [0°, 180°] and rotates counterclockwise around the y-axis. Step 102: Determine the aerodynamic characteristic matrix of the sail; The aerodynamic characteristics of the sail device are obtained based on single-sail aerodynamic analysis or model tests, and are characterized by dimensionless coefficient matrices Cn and Ct. Cn is the normal force coefficient matrix perpendicular to the sail axis in the sail coordinate system; Ct is the dimensionless axial force coefficient matrix along the sail axis in the sail coordinate system; The normal force coefficient Cn and the axial force coefficient Ct vary with the wind angle of attack β. The aerodynamic matrix of the sail is expressed as follows, where the value of β ranges from [0°, 180°] and the value of the wind angle of attack interval Δβ ranges from [1°, 10°]. Step 2: Predicting sail thrust characteristics and determining sail angle; Step 201: Define the ship's coordinate system to represent the relative wind direction angle α and the sail rotation angle θ, denoted as Coor.0, with the origin 0: taken as the intersection of the ship's stern perpendicular line, the mid-longitudinal section, and the baseline; X-axis: Longitudinal axis, with the positive direction pointing from the stern to the bow; Y-axis: The transverse axis, with the positive direction pointing from the ship's centerline to the port side; Z-axis: Vertical axis, its positive direction is perpendicular to the XY plane and upwards; The angle α between the sail and the wind direction of a ship is defined as the angle between the direction of the wind and the bow direction. Clockwise rotation is positive, and α ranges from [0°, 360°]. When the bow is directly facing the wind, α = 0°. The sail rotation angle θ refers to the angle through which the y-axis of the sail coordinate system rotates relative to the x-axis of the ship coordinate system. Clockwise rotation is positive and counterclockwise rotation is negative. The range of θ is [-90°, +90°]. Step 202: Determine the feasible range of sail rotation angle θ for each relative wind direction angle α. liml θ limr This allows for the generation of thrust along the ship's length within the sail angle range, and the effective sail angle matrix interval is calculated. The relative wind direction angle α ranges from [0°, 360°), and the i-th relative wind direction angle is denoted as α. i ; The interval Δα between relative wind direction angles is taken as 1°, for a total of 360 relative wind direction angles; α i The corresponding relative wind angle is i; θ liml θ represents the left limit of the sail rotation angle corresponding to the relative wind angle α. limr This represents the right limit of the sail turning angle corresponding to the relative wind direction angle; Relative wind angle α i When ∈ [0, 180], the left limit θ limli =-90°, right limit θ limri =-90°+α i ; Relative wind angle α i When ∈(180,360), the left limit θ limli =α i -270°, right limit θ limri =90°; θ limli Indicates with α i The corresponding left limit of the sail rotation angle, θ limri Indicates with α i The corresponding right limit of the sail rotation angle; Relative wind angle α i The corresponding number of feasible sail turning angles is θ limri -θ limli +1; Step 203: For each relative wind direction angle α i Iterate through each effective sail angle and calculate the corresponding angle of attack β. newij , to obtain β new A two-parameter two-dimensional matrix; Where, β newij This indicates the relative wind direction angle α i and its corresponding j-th relative sail rotation angle θ ij The angle of attack of the wind below; Angle of attack β newij It can be calculated by the following formula: β newij =270°+θ ij -α i ; Step 204: Calculate the wind attack angle β new The wind attack angle β is obtained by interpolating a two-parameter two-dimensional matrix with the single sail aerodynamic characteristic matrices Cn and Ct respectively. new The corresponding normal force coefficient matrix Cn_new and axial force coefficient matrix Ct_new; Relative wind angle α i Downwind angle of attack β newij The corresponding normal force coefficient matrix is ​​denoted as Cn_new ij The axial force coefficient is denoted as Cn_new ij ; The interpolation algorithm uses quadratic spline interpolation to ensure engineering accuracy; Step 205: For each relative wind direction angle α i sail angle θ ij Based on the aerodynamic matrix of the sail obtained in step 204 above, the thrust coefficient matrix fx in the hull coordinates is further calculated. Relative wind angle α i Downsail angle θ ij The corresponding thrust coefficient is denoted as fx ij It can be calculated using the following formula: yes ij =Cn_new ij ×cos(θ ij )-Ct_new ij ×sin(θ ij ); Step 206: For the relative wind direction angle α i Iterate through each sail turning angle θ ij The corresponding thrust coefficient fx ij The maximum thrust coefficient fx is obtained. i The sail thrust characteristics used to characterize the sail rotation at this relative wind angle are called the sail control angle θ. controli ; By iterating through all relative wind angles, we obtain the sail thrust coefficient matrix fx and the sail rotation control matrix θ. control ; Step 3: Forecast of the energy-saving effect of sail-assisted ships on specific routes; For specific routes, route planning and wind resource assessment are carried out, and the overall energy-saving effect of the sail is calculated by combining the sail thrust coefficient matrix obtained in step 206. Step 301: Route planning and wind information extraction; 1) Set the departure and arrival port positions of the target route, and divide the target route into several equal segments according to the standard sub-journey principle; the standard sub-journey is the distance the ship travels at an economical speed S. ship The distance traveled in 6 hours; for the last sub-journey, if it is less than the distance traveled by the ship in 3 hours at economic speed, it is disregarded. Thus, the target route is divided into N-1 segments of equal distance, with the initial and final points of each segment recorded as track points. This operation generates a total of N track points. Further, the longitude Lo of each track point is obtained. i and latitude La i (i=1,2,…,N), are recorded in database A; 2) Extract the original wind resource data under the latitude and longitude coordinates of the route over the past 10 years. When extracting wind information at the specific track point, the dispersion of the ship's trajectory is taken into consideration. The range of the single-sided extended domain is 0.3° x 0.3° with the track point as the center. In this way, the reference wind resource data on the target route is obtained, including "Vu0" and "Vv0" under "time", "longitude" and "latitude". Vu0 and Vv0 are the absolute wind speeds in the east-west and north-south directions, respectively, obtained directly from the geodetic coordinate system. The wind field data extraction precision is set to 0.125° x 0.125°, and the extraction times include 00:00, 06:00, 12:00, and 18:

00. By considering wind resources in all time periods, the wind field data for the target route is not limited by the departure time of the ship's characteristic voyage, and is more general and statistical. The k-th east-west wind speed component at the i-th track point is denoted as Vu0ik, and the south-north wind speed component is denoted as Vv0ik (i=1,2,…,N; k is the total number of wind fields within the extended domain). 3) Evaluate and filter valid wind field data, and update the wind field data for flight routes; For each track point, the absolute wind speed Vu0, Vv0, and composite wind speed within the extended domain at all times are calculated. The 3δ principle was used to perform deviation analysis. If any requirement was not met, the corresponding data was removed. The wind field data obtained from the wind resource database is the average wind speed at 10 meters above sea level, which is converted into the average wind speeds Vu and Vv at Zm above sea level using the following formulas: ； ； Zm is the distance from the center of the sail height of the sail-assisted vessel to the sea level; γ is the wind profile height coefficient. The above provides a revised database of effective wind resources for specific flight routes. Step 302: Calculate the relative wind direction and wind speed after considering the ship's speed; For each moment, the ship's speed S at track point i is... ship As the vector magnitude, the heading COGi is used as the vector direction, and it is vector-superimposed with the absolute wind speeds Vu0ik and Vv0ik in the effective wind resource database. The resulting vector magnitude is the relative wind speed AWS. ik The angle between the wind direction and the ship's heading is called the relative wind angle α. ik The component of a ship's speed in the east-west direction is denoted as Uship, and the component in the north-south direction is denoted as Vship. The heading at each trackpoint is the direction of the line connecting its adjacent trackpoints, and the heading at the last trackpoint is the same as the heading at the previous trackpoint. According to step 302, the relative wind speed and relative wind direction angle databases corresponding to all valid wind resource databases at all track points at all times can be calculated, including "time", "longitude", "latitude", "AWS" and "α"; the number of sample points in all databases is counted and denoted as M; Step 303: Forecast of the energy-saving effect of sail-assisted ships on specific routes; Based on the relative wind speed and relative wind direction angle database obtained in step 302, firstly, for each element m, the corresponding relative wind direction angle α is used... m Combining the interpolation from step 206 to obtain the corresponding sail thrust coefficient fxm, the sail propulsion power is then calculated using the following formula: ； In the above formula, A is the reference area of ​​the sail device, ρ is the air density, and fxm is the relative wind angle α. m The thrust coefficient of the sail under the current, AWS m This represents the relative wind speed corresponding to the m-th element; Considering the combined wind field conditions at all historical moments and after track points along the entire route, the calculated combined sail propulsion power is obtained by the following formula: 。

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