A Control Method for an Airfoil Sail Boosting System under Complex Marine Meteorological Conditions

Abstract

A control method for an airfoil sail boosting system under complex marine meteorological conditions, which rotates the sail to the angle with the minimum force, controls the actuating mechanism of the sail to raise the sail, rotates the sail to the angle that can provide the maximum boosting force, monitors the actual motion load of the ship based on the ship motion load once in a year in the North Atlantic as the standard, determines whether to lower the sail, evaluates the current working state of the sail and the ship state, determines whether there are changes in conditions such as operating conditions, meteorological environment, ship motion, and abnormal conditions, and needs to lower the sail according to the corresponding control method, rotates the sail to the angle with the minimum force to prepare for lowering the sail, controls the actuating mechanism of the sail to lower the sail, and then rotates the sail to the retracted state. The present invention forms a lifting control method applicable to different ship speeds and wind speeds for airfoil sail boosting devices with different numbers and sections, achieving the optimal sail operation purpose under complex wind and wave environments.

Description

Technical Field

[0001] The present invention belongs to the field of construction and design of sailboats, and particularly relates to a control method for an airfoil sail boosting system under complex marine meteorological conditions. Background Art

[0002] With the promulgation and implementation of new regulations on low-carbon emission reduction globally, the global shipping industry and shipbuilding industry are developing towards a green direction. Marine sails use clean energy such as wind energy as the driving force, setting off a new round of revolutionary wave internationally. The large ship group took the lead in carrying out the technical research on the world's first airfoil wind-assisted ocean-going cargo ship, breaking through a series of key technologies, including formulating the control method for this system.

[0003] Based on the aerodynamic characteristics, quantity, ship state, hull motion parameters, etc. of the sail itself, and on the research results of the sailing performance of the ship equipped with sails, with the best energy-saving effect as the control target and taking into account the sailing safety of the ship, this patent proposes a control method for the sail boosting system of a sailboat.

[0004] Since the sail system is an original innovation and there is no control method for reference, this control method is proposed for the first time. The boosting principle of the sail is to boost the ship forward through the pressure difference formed by the wind passing through the surface of the sail, and different wind direction angles will generate different boosting forces. Whether the sail is raised or lowered, an effective boosting force can be formed, that is, the control method should consider both the control method when the sail is raised and the control method when the sail is not raised. This is mainly considered to further increase the usage time of the sail. Under the lifting operation condition, the sail boosts at the designed wind speed in the raised state. When the wind speed exceeds the designed wind speed in the raised state, it continues to rotate to a favorable wind direction to form a boost under the lowering condition, and there is no limit to the designed wind speed under the lowering condition. Summary of the Invention

[0005] To solve the above problems, the present invention provides a control method for an airfoil sail boosting system under complex marine meteorological conditions, aiming to achieve the best energy-saving effect of the sailboat under complex marine meteorological conditions. The technical solution adopted is as follows:

[0006] A control method for an airfoil sail boosting system under complex marine meteorological conditions, the number of sails installed for boosting is N, and the sails are airfoil sails.

[0007]

[0008] Establish a hull coordinate system, a local coordinate system, and a sail coordinate system.

[0009] The origin of the hull coordinate system is the intersection of the ship's symmetric longitudinal section, the stern end, and the baseline, denoted as O. The X-axis is the longitudinal axis, positive forward; the Y-axis is the transverse axis, positive to the left; the Z-axis is the vertical axis, positive upward.

[0010] The origin of the local coordinate system is the center point of the sail base, denoted as o. The l-axis is in the same direction as the X-axis of the hull coordinate system, positive forward; the t-axis is in the same direction as the Y-axis of the hull coordinate system, positive to the left; the v-axis is in the same direction as the Z-axis of the hull coordinate system, positive upward.

[0011] The origin of the sail coordinate system coincides with the origin of the local coordinate system, denoted as o'. The x-axis of the coordinate system is perpendicular to the chord length direction of the sail section, positive forward; the y-axis of the coordinate system is in the same direction as the chord length direction of the sail section, positive to the right; the z-axis is the rotation axis of the sail, in the same direction as the Z-axis of the hull coordinate system, positive upward.

[0012] The specific control method of the sail boosting system is as follows:

[0013] S1: Rotate the sail to the angle with the minimum force

[0014] Before the sail is hoisted, rotate the sail to the angle with the minimum lateral force. When the relative wind direction is consistent with the direction of the x-axis of the sail coordinate system, the lateral force on the sail is the minimum. The relationship between the sail rotation angle θ and the relative wind direction angle α monitored in real time is:

[0015]

[0016] After the sail rotates, the included angle between the y-axis of the sail coordinate system and the l-axis of the local coordinate system is the sail rotation angle θ, positive for clockwise rotation;

[0017] The relative wind direction angle α is the included angle between the relative wind direction and the ship's X-axis. It is stipulated that the included angle between the wind coming from the ship's bow and the I-axis is 0°, positive for clockwise rotation;

[0018] S2: Group the sails and rotate them in the order of the groups

[0019] When N = 1, the sail can directly complete the rotation action through the actuating mechanism;

[0020] When N = 2n + 1, n = 1, 2, …, divide every 2 sails from the bow to the stern into a group, and the last 1 sail forms an independent group. First, rotate the group of sails closest to the bow, and then rotate each group of sails in order from the bow to the stern;

[0021] When N = 2n, n = 1, 2, …, divide every 2 sails from the bow to the stern into a group. First, rotate the group of sails closest to the bow, and then rotate each group of sails in order from the bow to the stern.

[0022] S3: Raise the sail according to the groups divided in S2 and the group order.

[0023] S4: After raising the sail, rotate the sail to the angle that can provide the maximum boost

[0024] Using the average wind direction Dt in the 10 minutes before the sail rotation as a parameter, adjust the rotation angle of the sail. Adjust it according to the grouping and group order in S2, and adjust the sail to the angle with the maximum boost. Among them,

[0025]

[0026] t is the time when the sail completes the rising action;

[0027] dt - 10i is the relative wind direction data in the 600 seconds before the t moment.

[0028] Obtain Dt through the relative wind direction data, and according to the Dt and rotation angle correspondence table, obtain the angle with the maximum boost.

[0029] S5: Recover the sail according to the motion state of the ship

[0030] Based on the inertial load once in 25 years in the North Atlantic, deduce the inertial load once in 1 year in the North Atlantic. The relationship between the inertial load once in 1 year in the North Atlantic and the inertial load once in 25 years in the North Atlantic is as follows:

[0031]

[0032] Among them, a , , , , CSR , ,

[0034] ,

[0033] , CSR ,

[0032] , s ,

[0036] , ,

[0035] is the acceleration response of the sail operation condition;

[0033] a CSR is the acceleration response calculated by the CSR specification;

[0034] ξ is the shape parameter of the two-parameter Weibull distribution, ξ = 1;

[0035] Taking the ship motion load once in 1 year in the North Atlantic as the standard, monitor the actual ship motion load, and real-time monitor the acceleration in the Y-axis direction of the ship. When the acceleration in the Y-axis direction of the ship exceeds 0.8125 × aCSR-y, give an alarm prompt and recover the sail. The sail recovery order is to recover the sails in sequence according to the group division and group order in S2.

[0036] If the peak value of the acceleration in the Y-axis direction of the ship exceeds 0.8125 × a for 2 consecutive minutes CSR-y, the sail needs to be retracted. The retraction sequence is carried out according to the group division and group sequence in S2, and the sail is continuously used by rotation. When the sail is raised, it can boost the ship by rotating the angle. Similarly, it can also boost the ship by rotation after retraction. The rotation sequence is the same as the sequence in S2.

[0037] Real-time monitor that the acceleration of the ship in the Z-axis direction exceeds 0.8125×a CSR -z, give an alarm to prompt sail retraction. If the peak acceleration in the Z-axis direction exceeds 0.8125×a for 2 consecutive minutes CSR -z, the sail needs to be retracted. The retraction sequence is the same as the sequence in S2, and the sail is continuously used by rotation. The rotation sequence is the same as the sequence in S2.

[0038] S6: Rotate the sail to the angle with the minimum force to prepare for lowering the sail. The rotation sequence is the same as the sequence in S2. After rotation, lower the sail to the retracted state.

[0039] For the above control method of the airfoil sail boosting system under complex marine meteorological conditions, further, before raising the sail, check whether there is a fault in the sail and the number of sails with faults. When the number of sails with system faults is greater than 3 / 4 of the total number, stop raising the sail.

[0040] For the above control method of the airfoil sail boosting system under complex marine meteorological conditions, further, in S4, for sails with different cross-sectional shapes, the actual control is carried out according to interval division. Divide [0°, 340°] into n intervals, and each interval corresponds to a rotation angle of the sail, and this angle is the angle that can provide the best boosting effect within this interval.

[0041] For the above control method of the airfoil sail boosting system under complex marine meteorological conditions, further, the range of the sail rotation angle θ is -90° to +90°.

[0042] For the above control method of the airfoil sail boosting system under complex marine meteorological conditions, further, after the sail is retracted, it should be placed in the "zero position state". When the port sail is in the zero position state, the sail rotation angle is -90°. When the starboard sail is in the zero position state, the sail rotation angle is +90°. The state after the sail is retracted is the zero position state, and the zero position state means the sail retracted state.

[0043] For the above control method of the airfoil sail boosting system under complex marine meteorological conditions, further, S5: Retract the sail according to the ship operation conditions or meteorological environment conditions.

[0044] For the above control method of the airfoil sail boosting system under complex marine meteorological conditions, further,

[0045] S5: Retract the sail according to the meteorological environment conditions

[0046] When the weather forecast shows that there will be a wind of over grade 8 or a weather condition with a temperature below 4°C within the next 24 hours, lower the sail to the zero position; or when the measured average atmospheric temperature Tt within 30 minutes is lower than 4°C, lower the sail to the zero position;

[0047] Let the time at each moment be t, and the time nodes 1800 seconds before the moment t be t - 10s, t - 20s, ……, t - 1800s. The corresponding atmospheric temperatures at these time nodes are dt - 10i. Take the average of these time nodes, which is Tt

[0048]

[0049] Or when the monitored wind speed V s ’ exceeds the design wind speed Vs, lower the sail;

[0050] When 0 < Vs - Vs’ ≤ 2, give an alarm. If the continuous alarm time exceeds 2 minutes, the mast will automatically lower one or more sections, and further judge whether the wind speed meets the requirements until the sail is retracted;

[0051] When Vs - Vs’ ≤ 0, the sail will automatically lower one or more sections, and further judge whether the wind speed meets the requirements until the sail is retracted.

[0052] The above control method for an airfoil sail boosting system under a complex marine meteorological condition, further,

[0053] S5: Recover the sail according to the ship operation condition. When the radar function effectiveness is affected after the sail is raised, the sail needs to be recovered.

[0054] The beneficial effects of the present invention are as follows:

[0055] 1. The control method of rotating the sail to the angle with the minimum lateral force before the sail rises or falls can minimize the wind load suffered by the sail during the lifting and lowering process, reduce the probability of jamming during lifting and lowering, reduce the wear of the moving mechanism components, and realize the reliability of the sail system operation;

[0056] 2. The control method of synchronous lifting and synchronous rotation can ensure that the maximum value of the electric power demand in the ship design remains unchanged, avoid excessive power demand, and thus avoid the phenomenon of increasing the number of generator startups, and ensure the stable power demand of the entire system;

[0057] 3. The sail lowering control method determined by the ship operation condition can ensure the safe operation of the ship, reduce the probability of ship failure, and at the same time provide a strong guarantee for the use of the sail;

[0058] 4. The sail-lowering control method determined by the meteorological environment takes the design wind speed as a limiting condition, determines the limiting wind speed at which the sails need to be lowered, provides a solution to reduce the number of sail surfaces, increases the available duration of the sails, and improves economy;

[0059] 5. Meanwhile, a control method is given based on weather forecasts and measured atmospheric temperatures to ensure the safety of sail use;

[0060] 6. The sail-lowering control method determined by ship motion gives the limit value of the inertial load caused by ship motion, avoids the occurrence of the phenomenon that the sail structure fails due to excessive inertial load, ensures the safety of the sails, and can directly obtain the inertial load with a return period of 1 year in the North Atlantic without the ship's hull form and accurate weight distribution, simplifying the method for obtaining the inertial load and meeting the requirements of engineering calculations;

[0061] 7. The sail-lowering control method induced by abnormal conditions provides the ship fault scenarios in which the sails need to be lowered, ensuring the safety of the ship and the sails.

[0062] 8. The rotation control method for the sail raising and retracting states provides the intervals in which the sails need to rotate and the wind direction reference, further extending the available duration of the sails and providing a strong guarantee for the sails to provide the maximum thrust. Description of the Drawings

[0063] Figure 1 It is a schematic diagram of the hull coordinate system;

[0064] Figure 2 It is a schematic diagram of the local coordinate system;

[0065] Figure 3 It is a schematic diagram of the sail coordinate system;

[0066] Figure 4 It is a schematic diagram when the sail rotation angle is 0°;

[0067] Figure 5 It is a schematic diagram when the sail rotates clockwise by an angle of θ°;

[0068] Figure 6 It is a schematic diagram of the sail retracted state, that is, the sail in the zero position state;

[0069] Figure 7 It is a schematic diagram of the relative wind direction angle;

[0070] Figure 8 It is a schematic diagram of the conversion between the wind speed at the top of the sail and the design wind speed;

[0071] Wherein: 1 - stern draft sensor, 2 - bow draft sensor, 3 - sail, 4 - main deck, 5 - waterplane, 7 - top of the sail, 8 - bottom of the ship. Detailed Implementation Manner

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

[0073] A control method for an airfoil sail boosting system under complex marine meteorological conditions, as Figure 1 , 2 , shown in Figure 3, first establish a hull coordinate system, a local coordinate system, and a sail coordinate system. The origin of the hull coordinate system is the intersection of the symmetric longitudinal section, the stern, and the baseline of the ship, denoted as O. The X-axis is the longitudinal axis, positive forward; the Y-axis is the transverse axis, positive to the left; and the Z-axis is the vertical axis, positive upward.

[0074] The origin of the local coordinate system is the center point of the sail base, denoted as o. The l-axis is in the same direction as the X-axis of the hull coordinate system, positive forward; the t-axis is in the same direction as the Y-axis of the hull coordinate system, positive to the left; and the v-axis is in the same direction as the Z-axis of the hull coordinate system, positive upward.

[0075] The origin of the sail coordinate system coincides with the origin of the local coordinate system, denoted as o'. The x-axis of the coordinate system is perpendicular to the chord length direction of the sail section, positive forward; the y-axis of the coordinate system is in the same direction as the chord length direction of the sail section, positive to the right; and the z-axis is the rotation axis of the sail, in the same direction as the Z-axis of the hull coordinate system, positive upward.

[0076] As Figure 4 shown, that is, the origin of the sail coordinate system coincides with the origin of the local coordinate system, and the direction of the y-axis of the sail coordinate system coincides with the direction of the l-axis of the local coordinate system, that is, the included angle between the y-axis of the sail coordinate system and the l-axis of the local coordinate system is 0°.

[0077] Suppose the number of installed sail boosters is N,

[0078]

[0079] 1. First, determine whether there is a fault in the sail and the number of faulty sails. If any sail has a system fault, that sail will not be raised, and the other sails will be raised normally for operation; if the number of sails with system faults is greater than 3 / 4 of the total number, then all sails will not be raised.

[0080] 2. Before raising the sail, rotate the sail to the angle with the minimum lateral force, and then raise the sail after rotation. Since there will be friction when the sail is raised under the action of wind force, in order to reduce the resistance generated by the friction, rotate the sail to the angle with the minimum force, which not only ensures the smooth rise of the sail but also reduces the wear of the sail-related components.

[0081] When the relative wind direction is consistent with the x-axis direction of the sail coordinate system, the lateral force on the sail is the minimum. The relationship between the sail rotation angle θ and the relative wind direction angle α monitored in real time is:

[0082]

[0083] If the relative wind direction angle α monitored in real time is within [0°, 180°], then rotate the sail angle θ to α - 90°. If the relative wind direction angle α monitored in real time is within (180°, 360°), then rotate the sail angle θ to α - 270°.

[0084] Such as Figure 5 、 6 As shown, that is, the included angle between the y-axis of the sail coordinate system and the l-axis of the local coordinate system is θ°. The range of the sail angle θ is from -90° to +90°. After the sail is retracted, in addition to continuing to use the wind energy to boost the ship, it should be placed in the "zero position state". When the port sail is in the zero position state, the sail angle is -90°; for the starboard sail in the zero position state, the sail angle is +90°.

[0085] When N = 1, the sail can directly complete the rotation action through the actuating mechanism.

[0086] When N = 2n + 1, n = 1, 2, …, divide every 2 sails from the bow to the stern into a group, and the last 1 sail forms an independent group. First, rotate the group of sails closest to the bow, and then rotate each group of sails in sequence from the bow to the stern.

[0087] When N = 2n, n = 1, 2, …, divide every 2 sails from the bow to the stern into a group. First, rotate the group of sails closest to the bow, and then rotate each group of sails in sequence from the bow to the stern.

[0088] Under normal operating conditions, the sails within a single group are rotated synchronously, that is, the starting time of rotation for each group of sails is the same.

[0089] 3. After raising the sail, rotate the sail to the angle that can provide the maximum boost force. Using the average wind direction Dt in the 10 minutes before the sail rotation as a parameter, adjust the rotation angle of the sail. Make the adjustment according to the grouping and grouping sequence in S2, and adjust the sail to the angle with the maximum boost force, where

[0090]

[0091] t is the time for the sail to complete the ascending action;

[0092] dt - 10i is the relative wind direction data in the 600 seconds before the t moment.

[0093] The Dt calculation method is as follows: Let the time for the sail to complete the ascending motion be t. Since the time step for the sail control system to record the real-time relative wind direction is 10 seconds, the relative wind direction data for the 10 minutes (600 seconds) before time t are dt-10i corresponding to the time points of t-10s, t-20s, ……, t-600s. The average value of the relative wind directions at these moments is Dt. As shown in Table 1, the sail boosting force angle is adjusted according to Dt.

[0094]

[0095]

[0096] Table 1 Sail Rotation Control Angle Comparison Table

[0097] For sails with different cross-sectional shapes, the turning angles for achieving the best boosting are also different. Here, an explanation of the interval division is given, and actual control can be carried out according to this. The interval [0°, 340°] is divided into n intervals, and each interval corresponds to a turning angle of the sail, and this angle is the angle that can provide the best boosting effect within this interval.

[0098] The formulation of the control method for the sail boosting system needs to comprehensively consider the wind field data in the geodetic coordinate system, the ship's navigation state, the sail thrust characteristics at different wind attack angles, and the inertial load of the sail boosting system caused by the ship's movement. From the wind field data in the geodetic coordinate system and the ship's navigation state, the wind field data in the hull coordinate system (i.e., the relative wind speed magnitude and relative wind direction angle) can be obtained. Based on this, and then considering the thrust characteristics of the sail at different attack angles, the control method for the turning angle of the sail boosting system is formulated.

[0099] As Figure 7 shown, the relative wind direction angle is the angle between the relative wind direction and the ship's X-axis, and the interval is from 0° to 360°. The wind coming from the ship's bow is 0°, and it rotates clockwise until 360°.

[0100] 4. According to the ship's motion state, ship operation conditions, or meteorological environment conditions, the sail is retracted, and specifically, it is divided into the following situations:

[0101] 1) The sail lowering control method determined by the ship operation conditions

[0102] In non-navigation conditions, the sail needs to be lowered to the zero position.

[0103] When the ship enters or leaves the port, the sail needs to be lowered to the zero position.

[0104] When the helicopter is operating, the sail needs to be lowered to the zero position.

[0105] When anchoring or mooring, the sail needs to be lowered to the zero position.

[0106] When overhauling the sail-assisted system, the sail needs to be lowered to the zero position.

[0107] When the ship encounters severe sea conditions, the sail needs to be lowered to the zero position.

[0108] When the ship passes through narrow waterways, bridges or areas with height restrictions, the sail needs to be lowered to the zero position.

[0109] When the raising of the sail affects the effectiveness of the radar function, the sail needs to be lowered to the zero position.

[0110] When using the signal light that requires the sail to be lowered, the sail needs to be lowered to the zero position.

[0111] 2) Sail lowering control method determined by meteorological environment

[0112] By combining meteorological forecasts and real-time wind field data monitoring, supplemented by the judgment of the crew, the sail-assisted system is controlled to operate at an appropriate wind force level and wind direction.

[0113] Taking the wind speed of level 8 as the limit wind speed, when the meteorological forecast shows that weather conditions with winds exceeding level 8 will occur within the next 24 hours, the crew operates to lower the sail to the zero position.

[0114] When the meteorological forecast shows that the weather will be below 4°C within the next 24 hours, to avoid icing, the crew operates to set the sail to the zero position (stowed position); when the measured average atmospheric temperature Tt within 30 minutes is below 4°C, the sail is automatically lowered to the zero position (stowed position). The calculation method of Tt is as follows: Let the time at each moment be t. Since the time step for the sail control system to record the real-time atmospheric temperature is 10 seconds, the atmospheric temperature data at 30 minutes (1800 seconds) before the t moment are dt-10i corresponding to the time points of t-10s, t-20s,..., t-1800s. The average value of the atmospheric temperatures at these moments is Tt.

[0115]

[0116] Under the condition of sail hoisting, when the monitored wind speed exceeds the designed wind speed Vs of the sail, there is a risk of sail structure failure and sail lowering is required. The control method is as follows: when 0 < designed relative wind speed - relative wind speed at the sail top ≤ 2, the control system gives an alarm. When the alarm time exceeds the designed time, the sail automatically descends one or more sections to determine whether the wind speed meets the requirements until all sail surfaces are completely lowered and retracted to the zero position; when designed relative wind speed - relative wind speed at the sail top ≤ 0, since the sail is multi-sectioned, it automatically descends one or more sections to determine whether the wind speed meets the requirements until all sail surfaces are completely lowered and retracted to the zero position. Since the relative wind speed cannot be directly obtained at the sail top, it needs to be obtained through conversion using the ship's draft and relevant parameters of the sail itself, which are described in detail below.

[0117] Set an alarm device. The designed wind speed at the sail top of the sail is Vs, and the wind speed V0 at a height of 10 meters above sea level can be obtained on the ship. V0 can be transformed to obtain the monitored wind speed Vs' at the sail top. When 0 < Vs - Vs' ≤ 2, an alarm is given. When the continuous alarm time exceeds 2 minutes, the sail automatically descends one or more sections to further determine whether the wind speed meets the requirements until all sail surfaces are completely lowered and retracted to the zero position; when Vs - Vs' ≤ 0, the sail automatically descends one or more sections to further determine whether the wind speed meets the requirements until all sail surfaces are completely lowered and retracted to the zero position.

[0118] To obtain the monitored wind speed Vs' at the sail top, first, the wind speed V0 at a height of 10 meters above sea level needs to be obtained, and then it is calculated through the formula specified in the following specifications.

[0119]

[0120] Where H is the distance from the sail top to sea level. Then, as long as H is obtained in the above formula, Vs' can be obtained, and the method is as follows.

[0121] As Figure 8 shown, the forward draft of the ship measured by the forward draft sensor 2 and the aft draft sensor 1 is TF, the aft draft is TA, the distance between the forward draft sensor 2 and the aft draft sensor 1 is LA, the distance from the sail 3 to the aft draft sensor 1 of the ship is LS, and the molded depth of the ship is D. Then the draft TS at the position of the sail is:

[0122]

[0123] Then the distance from the main deck 4 at the position of the sail to the waterline surface 5 is D - TS. At the same time, obtain

[0124]

[0125] By subtracting the draft TS at the position of the sail from the distance between the top of the sail 7 and the bottom of the ship 8, and then projecting it in the direction perpendicular to the sea level, the vertical distance H between the top of the sail 7 and the waterline plane 5 can be obtained. Among them, the distance between the top of the sail 7 and the bottom of the ship 8 can be obtained by adding the distance HS between the top of the sail 7 and the main deck 4 and the molded depth D of the ship. The above calculation process is as follows:

[0126] H = (HS + D - TS)cosβ

[0127] Substituting the vertical distance H between the top of the sail 7 and the waterline plane 5 into the following formula, the monitored wind speed Vs' at the top of the sail can be obtained.

[0128]

[0129] When the wind speed does not meet the requirements, one or more sail surfaces need to be lowered. There are n sail surfaces 6 on the sail, and the height of each sail surface is B. Then the calculation of H at this time is as follows:

[0130] H = (HS + D - TS - NB)cosβ, n - 1 > N ≥ 0

[0131] Substitute H back into the following formula to judge whether the wind speed requirement is met.

[0132]

[0133] For example, when all the sails are fully raised, at this time H = (HS + D - TS)cosβ, and the wind speed V0 at a height of 10 meters from the sea level is measured. Then

[0134]

[0135] If it is judged that the sail needs to be lowered at this time, the topmost sail surface can be lowered, and the other sail surfaces remain unchanged. Then calculate Vs' after lowering one sail surface. At this time

[0136] H = (HS + D - TS - B)cosβ, then

[0137]

[0138] Continue to compare the current Vs' with Vs and make a judgment, and so on.

[0139] When the continuously monitored reference wind direction remains in the range of [0° to 20°) and (340° to 360°) for 10 consecutive minutes, prompt the crew to set the sail to the zero position; when the continuously monitored reference wind direction remains in the range of [20° to 340°] for 10 consecutive minutes, and at the same time Vs' + 4 is less than Vs, prompt the crew to raise the sail.

[0140] 3) Sail lowering control method determined by ship motion

[0141] Based on the inertial load with a recurrence interval of 25 years in the North Atlantic, the inertial load with a recurrence interval of 1 year in the North Atlantic is derived. The relationship between the inertial load with a recurrence interval of 1 year in the North Atlantic and the inertial load with a recurrence interval of 25 years in the North Atlantic is as follows:

[0142]

[0143] where a s is the acceleration response under the sail operation condition;

[0144] a CSR is the acceleration response calculated according to the CSR code;

[0145] ξ is the shape parameter of the two-parameter Weibull distribution, ξ = 1;

[0146] Taking the ship motion load with a recurrence interval of 1 year in the North Atlantic as the standard, the actual ship motion load is monitored, and the acceleration in the Y-axis direction of the ship is monitored in real time. When the acceleration in the Y-axis direction of the ship exceeds 0.8125×aCSR-y, an alarm is given and the sail is lowered. The sails are lowered in sequence according to the group division and group order in S2.

[0147] If the peak value of the acceleration in the Y-axis direction of the ship exceeds 0.8125×a CSR -y for 2 consecutive minutes, the sails need to be retracted. The retraction sequence is carried out according to the group division and group order in S2, and the sails can be reused by rotation. The rotation sequence is the same as the sequence in S2.

[0148] When the acceleration in the Z-axis direction of the ship monitored in real time exceeds 0.8125×a CSR -z, an alarm is given to lower the sail. If the peak value of the acceleration in the Z-axis direction exceeds 0.8125×a CSR -z for 2 consecutive minutes, the sails need to be retracted. The retraction sequence is the same as the sequence in S2, and the sails can be reused by rotation, and the rotation sequence is the same as the sequence in S2.

[0149] When designing the sail structure, the ship motion load (acceleration) with a recurrence interval of 1 year in the North Atlantic is adopted. However, during the operation of the ship, the ship motion load (acceleration) caused by waves has a probability of exceeding the ship motion load with a recurrence interval of 1 year in the North Atlantic. Therefore, it is necessary to monitor the ship operation load. Once it approaches or exceeds the limit value, the sails need to be lowered to the zero position according to the specified control method.

[0150] Since the Code gives the ship motion loads with a return period of 25 years in the North Atlantic, but does not give the ship motion loads with a return period of 1 year in the North Atlantic, here through calculation, based on the ship motion loads with a return period of 25 years in the North Atlantic, multiplying by a coefficient, the ship motion loads with a return period of 1 year in the North Atlantic are obtained. The specific process of obtaining this coefficient is described as follows.

[0151] When designing the structure of the sail, in addition to considering the wind load brought by the design wind speed, another part is the inertial load (acceleration) generated by the ship motion. Since the sail is installed on the main deck or other positions of the ship, the inertial load it receives is provided by the ship motion, so the design can refer to the inertial load of the ship.

[0152] When designing the main structure of a large ocean-going cargo ship, the ship motion loads with a return period of 25 years specified in the Common Structural Rules for Ships are used. At present, the operating wind speed of the sail is 25 m / s, corresponding to sea state 8. The calculation of the inertial load is related to both the short-term and long-term sea state responses of the waves. Through hydrodynamic analysis, the inertial load with a return period of 1 year in the North Atlantic (long-term sea state response) is sufficient to cover the inertial load (short-term sea state response) in the sea state 8 environment. If the ship motion loads with a return period of 25 years in the Common Structural Rules for Ships are directly used for the sail structure design, the resulting structural dimensions will be too conservative.

[0153] For the short-term sea state response (parameters such as inertial load), the current acquisition method is obtained through computational fluid dynamics (CFD). And due to the different designs of each ship, CFD analysis needs to be carried out for the inertial load, resulting in a huge workload. As described above, the inertial load with a return period of 1 year in the North Atlantic (long-term sea state response) is sufficient to cover the inertial load (short-term sea state response) in the sea state 8 environment. For the convenience of design, based on the inertial load with a return period of 25 years in the North Atlantic, the inertial load with a return period of 1 year in the North Atlantic can be directly obtained through a given coefficient, which not only reduces the design threshold but also significantly shortens the design cycle.

[0154] The long-term response is related to the exceedance probability level or return period. The Code states that for the exceedance probability level with a return period of X years in the North Atlantic:

[0155] Q X (y>y D )=n / n X

[0156] where Q X (y>y D ) is the probability that the wave extreme value y is greater than y D , that is, under a certain probability distribution, statistically greater than y DThe probability of a wave extreme value recurring is n, nx is the total number of times, 3600 is the number of seconds in an hour, 24 is the number of hours in a day, 365 is the number of days in a year, X is the number of years, and Tm is the average wave period (about 7.5 seconds). Then nx is in the following form:

[0157]

[0158] If X is 25 years, then

[0159]

[0160] So

[0161] Q 25 (y>y D )=n / n 25 ∞10 -8

[0162] That is, for the inertial load of the North Atlantic Ocean that occurs once every 25 years, it is equivalent to a exceedance probability level of 10-8.

[0163] For the 1-year inertial load in the North Atlantic, this is equivalent to:

[0164] Q1(y>y D )=n / n1

[0165]

[0166] Q1(y>y D )=n / n1∞10 -6.5

[0167] This is equivalent to a exceedance probability level of 10-6.5.

[0168] The long-term distribution of extreme values of the response, represented by the two-parameter Weibull distribution function.

[0169]

[0170] Among them, FX(y D ) is the discretized extreme long-term distribution, ξ is the shape parameter of the two-parameter Weibull distribution, k is the scale parameter of the two-parameter Weibull distribution, y D For the Weibull distribution, the extreme value is greater than y D The probability is:

[0171] Q X (y>y D )=1-F X (y D )

[0172] When X=25, yD Take the acceleration a25 with a return period of 25 years in the North Atlantic. Then

[0173] Q 25 (y > y D ) = 1 - F 25 (y D )

[0174]

[0175] Similarly, when X = 1, y D Take the acceleration a1 with a return period of 1 year in the North Atlantic. Then

[0176]

[0177]

[0178] Then it can be obtained that

[0179]

[0180] Through hydrodynamic analysis, ξ = 1, that is:

[0181]

[0182] From this, the relationship between the inertial load with a return period of 1 year and the inertial load with a return period of 25 years in the North Atlantic is as follows:

[0183]

[0184] Among them, a s is the acceleration response under the sail operation condition; a CSR is the acceleration response calculated according to the CSR specification; ξ is the shape parameter of the two-parameter Weibull distribution, and ξ = 1.

[0185] Then the acceleration control methods for the Y-axis and Z-axis directions of the ship are as follows:

[0186] Real-time monitor that the acceleration in the Y-axis direction of the ship exceeds 0.8125×a CSR -y, and give an alarm to prompt to lower the sail. If the peak acceleration in the Y-axis direction exceeds 0.8125×a CSR -y for 2 minutes continuously, the sail needs to be retracted, and the sail can be continued to be used by rotation.

[0187] Real-time monitor that the acceleration in the Z-axis direction of the ship exceeds 0.8125×a CSR -z, and give an alarm to prompt to lower the sail. If the peak acceleration in the Z-axis direction exceeds 0.8125×a CSR -z for 2 minutes continuously, the sail needs to be retracted, and the sail can be continued to be used by rotation.

[0188] 4) Sail lowering control method induced by abnormal conditions

[0189] If all anemometers and wind vanes fail or are inaccurate, the sails should be set to the zero position.

[0190] If the accelerometer fails or is inaccurate, the sails should be set to the zero position, and then the sails should be continued to be used according to the rotation control method.

[0191] Under operating conditions, if any one sail or two sails have system failures, that sail should be set to the zero position, and the other sails should operate normally; if the number of sails with system failures is greater than 3 / 4 of the total number, all sails should be set to the zero position.

[0192] When a fire breaks out on the ship, the sails should be set to the zero position.

[0193] When the main power supply of the ship is lost and it is powered by the emergency power supply, the sails should be set to the zero position.

[0194] When other failures that the crew judges affect the safe operation of the ship, such as the ship suffering from a broken cabin, collision, grounding, etc., the sails should be set to the zero position.

[0195] 5. When the sails reach the recovery condition, rotate the sails to the angle with the minimum force to prepare for lowering the sails. The rotation order is the same as that in S2. After rotation, lower the sails to the recovery state. When all the sails are lowered, rotate to the zero position (as Figure 6 shown), that is, the port sail rotates to -90° and the starboard sail rotates to +90°.

Claims

1. A control method for an airfoil sail boosting system under complex marine meteorological conditions, characterized in that: The number of sails installed is N, and the sails are airfoil sails. ； Establish a hull coordinate system, a local coordinate system, and a sail coordinate system. The origin of the hull coordinate system is the intersection of the symmetric longitudinal section, the stern, and the baseline of the ship, denoted as O. The X-axis is the longitudinal axis, positive forward; the Y-axis is the transverse axis, positive to the left; the Z-axis is the vertical axis, positive upward. The origin of the local coordinate system is the center point of the sail base, denoted as o. The l-axis is in the same direction as the X-axis of the hull coordinate system, positive forward; the t-axis is in the same direction as the Y-axis of the hull coordinate system, positive to the left; the v-axis is in the same direction as the Z-axis of the hull coordinate system, positive upward. The origin of the sail coordinate system is the same as that of the local coordinate system, denoted as o’. The x-axis direction of the sail coordinate system is perpendicular to the chord length direction of the sail section, positive forward; the y-axis direction of the sail coordinate system is the same as the chord length direction of the sail section, positive to the right; the z-axis is the rotation axis of the sail, in the same direction as the Z-axis of the hull coordinate system, positive upward. The specific control method of the sail boosting system is as follows: S1: Rotate the sail to the angle with the minimum force. Before raising the sail, rotate the sail to the angle with the minimum lateral force. When the relative wind direction is the same as the x-axis direction of the sail coordinate system, the lateral force on the sail is the minimum. The relationship between the sail rotation angle θ and the relative wind direction angle α monitored in real time is: ； After the sail rotates, the angle between the y-axis of the sail coordinate system and the l-axis of the local coordinate system is the sail rotation angle θ, positive for clockwise rotation. The relative wind direction angle α is the angle between the relative wind direction and the X-axis of the ship. It is stipulated that the angle between the wind coming from the bow of the ship and the X-axis of the ship is 0°, positive for clockwise rotation. S2: Group the sails and rotate them in the order of the groups. When N = 1, the sail can directly complete the rotation action through the actuating mechanism. When N = 2n + 1, n = 1, 2, …, group every 2 sails from the bow to the stern, and the last 1 sail forms an independent group. First, rotate the group of sails closest to the bow, and then rotate each group of sails in order from the bow to the stern. When N = 2n, n = 1, 2, …, group every 2 sails from the bow to the stern. First, rotate the group of sails closest to the bow, and then rotate each group of sails in order from the bow to the stern. S3: Raise the sails according to the groups and the group order divided in S2. S4: After raising the sails, rotate the sails to the angle that can provide the maximum boosting force. Taking the average wind direction Dt in the 10 minutes before the sail rotates as a parameter, adjust the rotation angle of the sail. Adjust according to the groups and the group order in S2, and adjust the sail to the angle with the maximum boosting force, where ； t is the time for the sail to complete the rising action. d t-10i is the relative wind direction data for the 600 seconds before time t; S5: Recover the sails according to the motion state of the ship. Based on the inertial load with a return period of 25 years in the North Atlantic, the inertial load with a return period of 1 year in the North Atlantic is derived. The relationship between the inertial load with a return period of 1 year in the North Atlantic and the inertial load with a return period of 25 years in the North Atlantic is as follows: ； where α s is the acceleration response under the sail operation condition; α csr Acceleration response calculated for the CSR specification; ξ is the shape parameter of the two-parameter Weibull distribution, ξ = 1. Taking the ship motion load with a return period of 1 year in the North Atlantic as the standard, monitor the actual ship motion load, and real-time monitor the acceleration in the Y-axis direction of the ship. When the acceleration in the Y-axis direction of the ship exceeds 0.8125×α csr -y, give an alarm prompt and retract the sail. The sails are retracted in sequence according to the group division and group sequence in S2; If the peak value of the ship's acceleration in the Y-axis direction exceeds 0.8125×α for 2 consecutive minutes csr -y, the sail needs to be retracted. The retraction sequence is carried out according to the group division and group sequence in S2, and the sail is continued to be used by rotation. The rotation sequence is the same as the sequence in S2; Real-time monitor that the acceleration of the ship in the Z-axis direction exceeds 0.8125×α csr -z, give an alarm prompt and retract the sail. If the peak acceleration in the Z-axis direction exceeds 0.8125×α csr -z for 2 minutes continuously, the sail needs to be retracted. The retraction sequence is the same as that in S2, and the sail continues to be used by rotation. The rotation sequence is the same as that in S2; S6: Rotate the sail to the angle with the minimum force to prepare for lowering the sail. The rotation order is the same as that in S2. After rotation, lower the sail to the recovery state.

2. The control method of an airfoil sail boosting system under complex marine meteorological conditions according to claim 1, characterized in that: Before raising the sail, check whether there are any faults in the sails and the number of faulty sails. When the number of sails with system faults is greater than 3 / 4 of the total number, stop raising the sail.

3. A control method for an airfoil sail boosting system under complex marine meteorological conditions according to claim 1, characterized in that: In S4, for sails with different cross-sectional shapes, the actual control is carried out according to interval division. The range [0°, 340°] is divided into n intervals, and each interval corresponds to a rotation angle of the sail, which is the angle that can provide the best boosting effect within that interval.

4. A control method for an airfoil sail boosting system under complex marine meteorological conditions according to claim 1, characterized in that: The range of the sail rotation angle θ is from -90° to +90°.

5. A control method for an airfoil sail boosting system under complex marine meteorological conditions according to claim 1, characterized in that: After the sail is retracted, it should be placed in the "zero position state". In the zero position state of the port sail, the sail rotation angle is -90°, and in the zero position state of the starboard sail, the sail rotation angle is +90°.

6. A control method for an airfoil sail boosting system under complex marine meteorological conditions according to claim 1, characterized in that: S5: Retract the sail according to the ship operation conditions or meteorological environment conditions.

7. A control method for an airfoil sail boosting system under complex marine meteorological conditions according to claim 6, characterized in that: S5: Retract the sail according to the meteorological environment conditions When the weather forecast shows that there will be a wind of over 8 levels or a temperature below 4°C within the next 24 hours, lower the sail to the zero position state; or when the measured average atmospheric temperature Tt within 30 minutes is lower than 4°C, lower the sail to the zero position state; Let the time at each moment be t, and the time nodes 1800 seconds before the t moment are t - 10s, t - 20s,..., t - 1800s. The corresponding atmospheric temperatures at these time nodes are dt - 10i. Take the average value of these time nodes, which is Tt ； Or when the monitored wind speed Vs' exceeds the designed wind speed Vs, retract the sail; When 0 < Vs - Vs’ ≤ 2, an alarm is given. If the continuous alarm time exceeds 2 minutes, the mast automatically lowers one or more sections, and further judge whether the wind speed meets the requirements until the sail is retracted; When Vs - Vs’ ≤ 0, the sail automatically lowers one or more sections, and further judge whether the wind speed meets the requirements until the sail is retracted.

8. A control method for an airfoil sail boosting system under complex marine meteorological conditions according to claim 6, characterized in that: S5: Retract the sail according to the ship operation conditions When the radar function effectiveness is affected after the sail is raised, the sail needs to be retracted.

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