A method for verifying sail force matrix through sea trials

Abstract

This invention discloses a method for verifying the sail force matrix through sea trials. The method determines the propulsion power generated by the sail by measuring changes in ship speed and main engine power when the sail is in use and not in use. Simultaneously, it requires measuring speed and power data at at least five relative wind angles. This allows for the fitting of a dimensionless coefficient curve, which can then be used to verify the dimensionless coefficient curve obtained from CFD simulations or wind tunnel tests, thereby verifying the sail force matrix. This invention can directly obtain dynamic force data of the sail during actual navigation, simulating a real marine environment, resulting in more accurate verification data. By inferring the sail force matrix from actual ship test data, the iteration cycle of sail design can be significantly shortened.

Description

Technical Field

[0001] This invention belongs to the field of marine ship construction and design, and specifically relates to a method for verifying the sail force matrix through sea trials. Background Technology

[0002] With the promulgation and implementation of new low-carbon emission reduction regulations worldwide, the global shipping and shipbuilding industries are moving towards green development. Marine sail systems, powered by clean wind energy, are sparking a new wave of revolution internationally. Dalian Shipbuilding Industry Group (DSIC) pioneered the world's first research on airfoil-driven wind-assisted ocean-going freighters, breaking through a series of key technologies and completing a solution for installing sail systems on ultra-large vessels.

[0003] Currently, the dominant factor in evaluating the energy-saving effect of sails is the sail force matrix, which belongs to the sail itself and determines the extent of energy savings. This matrix can be obtained through CFD simulation or wind tunnel testing. However, the accuracy of CFD simulation parameters or the model scale in wind tunnel testing limits the determination of the energy-saving effect of real-scale sails. Therefore, it is necessary to verify the force matrix obtained from CFD simulation or wind tunnel testing through real-scale experiments.

[0004] To address the aforementioned problems, this invention proposes a method for conducting experiments during the sea voyage phase, thereby verifying the force matrix obtained through CFD simulation or wind tunnel testing. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a method for verifying the sail force matrix through sea trials. The aim is to simulate the actual marine environment and deduce the sail force matrix from real-ship test data, thereby significantly shortening the iteration cycle of sail design. The technical solution adopted is as follows:

[0006] A method for verifying the sail force matrix through sea trials is proposed. The ship begins to sail in the test area, keeping its bow unchanged during each measurement cycle. After one measurement cycle, the ship's relative wind direction angle is changed, and the next measurement cycle begins. The measurement cycle consists of at least 5 cycles, with the relative wind direction angle step sizes falling on (20°, 50°], (50°, 80°], (80°, 110°], (110°, 140°], and (140°, 180°), respectively.

[0007] The test begins, confirming that the test environment conditions are within the specified range and that the wind-powered booster is in an unused condition. The approach phase is completed while maintaining the same heading.

[0008] Prepare to begin all measurements using two types of data acquisition: one for automatic data acquisition via a data acquisition system, and the other for manual data recording via a log sheet.

[0009] Once torque, speed, and heading are stable, begin the test and record data for at least 10 minutes to ensure the acquisition of the necessary data for WPSFM. During WPSFM operation, conduct environmental observations, activate the wind-assisted propulsion system to bring it into operational condition, and navigate the vessel with a rudder angle not exceeding 5°, changing the relative wind direction angle. Acquire at least 5 test data points for the relative wind direction angle before concluding the test. Wind Propulsion System Force Matrix (WPSFM)

[0010] After the experiment is completed, the measurement data should be processed in the following order:

[0011] a) Derive the average values ​​of the parameters measured in each test cycle, including the ship's power Psi and speed Vsi, i≥5 when the wind-powered propulsion device is not in use, and the ship's power Poi and speed Voi, i≥5 when the wind-powered propulsion device is in use. The ship's speed is derived from the interval between the start and end positions and the time elapsed during rapid travel.

[0012] b) For the unused wind-powered propulsion device in each test cycle, the target ship's speed-power curve P0-V0 is obtained by correcting the measured wind speed parameters, calculated flow parameters, and measured water depth parameters.

[0013] P0-V0 represents the speed-power curve under calm, shallow water conditions.

[0014] c) The average wind speed, flow, and the influence of shallow water on velocity power measured in the operating conditions of the wind booster in each measurement cycle are corrected to P0-V0 in opposite ways to obtain the curve Pi-Vi, i≥5.

[0015] d) Interpolate the average speed Voi measured in the operating conditions of the wind-powered booster on the Pi-Vi curve to obtain the corresponding power Poi'. Calculate the difference between the measured power Poi and the power Poi' obtained from the test of the wind-powered booster in the operating conditions to obtain ΔPi under a certain measurement period. This ΔPi is the boost power corresponding to the relative wind direction angle under the operating conditions of the wind-powered booster.

[0016] e) Calculate the propulsion efficiency ηDi of the corresponding Voi through the model test report. Then the thrust Fi generated by the wind-powered booster under the operating conditions can be calculated as: Fi=△Pi×ηDi / Voi / A, where A is the area of ​​the sail.

[0017] f) Based on the wind tunnel test or CFD test report of the wind booster, the thrust Fi provided by the wind booster under the operating conditions is dimensionless to obtain the dimensionless coefficient ε corresponding to different wind direction angles.

[0018] g) The least squares method is used to calculate the weight between the dimensionless coefficient ε and the dimensionless curve obtained from wind tunnel tests or CFD under different wind direction angles during the operation of the wind-powered booster.

[0019] This weight can be used as a coefficient for subsequent energy efficiency evaluation of wind-powered booster devices, i.e., the dimensionless coefficient curve obtained by scaling up or down the CFD proportionally.

[0020] The above-mentioned method for verifying the sail force matrix through sea trials further corrects for environmental impact during the test by sequentially removing the influence of superstructure wind load on power and the influence of current and shallow water on speed from the measurement data of each measurement cycle obtained under the condition that the wind-powered booster is not in use, thus obtaining the speed-power curve P0-V0 under the conditions of no wind, no current, and deep water.

[0021] Then, the effects of wind, current, and water depth on the superstructure under the operating conditions of the wind-powered propulsion device are reversed to obtain a new speed-power curve P1-V1. Assuming there is a ship identical to the test vessel but without the wind-powered propulsion device, its speed-power curve is P1-V1.

[0022] The power at a given speed is obtained by interpolating the speed V obtained from the operating condition test of the wind-powered booster onto the P1-V1 curve. The difference between this power and the power obtained from the non-operating condition test of the wind-powered booster is then multiplied by the propulsion efficiency at speed V in the model test report. This yields the boost power provided by the wind-powered booster.

[0023] Furthermore, the aforementioned method for verifying the sail force matrix through sea trials should, at the end of each run, be able to present the history of all recorded times for all recorded parameters to assess the quality and consistency of the collected test data and store it for subsequent graphical display.

[0024] Furthermore, in the above-mentioned method for verifying the sail force matrix through sea trials, the wind speed-related parameters are relative wind direction and relative wind speed.

[0025] Furthermore, in the aforementioned method for verifying the sail force matrix through sea trials, the data acquisition system is a measurement computer.

[0026] Furthermore, the above-mentioned method for verifying the sail force matrix through sea trials further requires that the wind speed used in the test be one that can significantly provide changes in shaft power, and not exceed Beaufort scale 10. The duration of the wind speed should cover the entire test cycle, the sea state should not exceed level 8, and the test area should be free from obstruction by small boats and commercial traffic.

[0027] The beneficial effects of this invention are:

[0028] 1. Traditional sail load calculations rely on wind tunnel tests or numerical simulations, but lack the complex variables of the actual marine environment (such as sudden wind speed changes, wave impacts, and ship rolling). Sea trials can directly obtain dynamic force data of the sail during actual navigation, verifying more accurate data.

[0029] 2. By back-deriving the sail force matrix from actual ship test data, the iteration cycle of sail design can be significantly shortened.

[0030] 3. Based on force matrix data, a collaborative control model of sail and control strategy can be established, providing technical support for the formulation of control strategy. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the process from the first measurement cycle to the second measurement cycle.

[0032] Figure 2 This is a flowchart of the present invention. Detailed Implementation

[0033] The present invention will be described in detail with reference to specific embodiments.

[0034] A method for verifying sail force matrix through sea trials. The trial preparation involves assembling all the necessary test instruments and testing them for malfunctions or other problems. The availability of the following equipment is confirmed:

[0035] a) Gyroscope compass;

[0036] b) Anemometer;

[0037] c) Barometer;

[0038] d) Ship speed recording system (preparing for calibration);

[0039] e) Ship draft measurement system, including longitudinal and vertical offsets (if any) relative to the appropriate draft reading;

[0040] f) Water depth measurement system;

[0041] g) Shaft torque and shaft speed measurement system;

[0042] h) Global Navigation Satellite System.

[0043] Test conditions

[0044] Since this invention compares the change in shaft power over a test cycle, for ships, as long as there are no significant changes in various parameters of the ship during the test cycle, such as displacement, trim, heel, and propeller pitch, the requirements can be met.

[0045] The wind speed should be chosen to clearly indicate the change in axial power, and should not exceed Beaufort scale 10, with sea state not exceeding force 8. Ideally, the area should be free from obstruction by small boats and commercial traffic.

[0046] During a test cycle, wind and airflow should be kept as consistent as possible to minimize the negative impact of corrections made due to these factors. Wind data can be recorded by instruments, while airflow data can be obtained through calculations.

[0047] The force matrix of a wind-powered propulsion system can be obtained through wind tunnel testing or CFD analysis. Due to the influence of ship attitude and wind, the force matrix of the wind-powered propulsion system varies under different ship operating conditions. Therefore, similar to tank testing, force matrices of the wind-powered propulsion system under ballast and full-load conditions are needed to correspond to the ship's operating conditions during testing.

[0048] Measurement parameters

[0049] The parameters measured during the test cycle include: date, weather conditions, temperature, air pressure, torque meter reading, ship position, test area, draft, displacement, windward area, superstructure lateral projection area, waterline lateral projection area, ground speed, water speed, shaft torque or shaft power, shaft speed, time, elapsed time during the measurement process, water depth, bow heading, relative current speed and direction, and relative wind speed and direction.

[0050] The following parameters require further explanation.

[0051] a) Ship track and speed

[0052] The ship's position and speed should be measured using a Global Positioning System (GPS) such as a Global Navigation Satellite System (GNSS). The positioning system should operate in differential mode to ensure sufficient accuracy. Position and speed should be continuously monitored and stored.

[0053] b) Torque

[0054] The calibration of the torque measurement system must not be altered during WPSFM testing. Torque and speed measurements should be continuously monitored and stored.

[0055] c) Wind

[0056] The wind measured in the experiment should be as close as possible to the undisturbed wind speed encountered by the ship. If an anemometer is used for the experimental measurement, it should be placed in a suitable location to minimize the influence of airflow distortion on the measured wind speed. Wind speed and direction measurements should be continuously monitored and stored.

[0057] d) Water depth

[0058] Water depth can be determined by examining the nautical charts of the test area or by measuring it during navigation using the ship's echo sounder. It is important to calibrate the echo sounder before operation at speed, taking into account the ship's draft (sensor depth). Calibration should be combined with a comparison of the indicated depth with the water depths given on the test area charts. Water depth measurements should be continuously monitored and stored.

[0059] e) Air properties

[0060] Upon arrival at the WPSFM test area, air temperature and air pressure should be measured using calibrated thermometers and barometers, respectively.

[0061] f) Flow

[0062] Flow velocity and direction should be determined as part of the data for each test cycle by calculating the velocity relative to the ground, the velocity relative to the water, and the ship's course.

[0063] test

[0064] Before the experiment, the weather forecast should be studied to ensure the following conditions are met.

[0065] 1) The wind speed during the test can produce significant power changes.

[0066] 2) The duration of the wind speed is sufficient to cover the entire test cycle.

[0067] like Figure 1 As shown, the vessel begins navigation in the test area, maintaining a constant bow heading throughout each measurement cycle. After one measurement cycle, the vessel's relative wind angle is changed to begin the next measurement cycle, as follows: Figure 1 As shown. The measurement cycle should be at least 5, and the step size of the relative wind direction angle should be as uniform as possible, preferably falling on (20°, 50°], (50°, 80°], (80°, 110°], (110°, 140°] and (140°, 180°) respectively.

[0068] The test duration should be long enough to allow for reliable speed / power measurements within the required accuracy range. The run duration at all speeds should be identical, at least 10 minutes. Speed ​​runs at the same power setting should be evenly distributed across the measurement cycles.

[0069] During the measurement cycle, an experienced helmsman or adaptive autopilot is required to maintain the course. Minimum rudder angle should be used while maintaining course stability. During speed operation, the maximum single amplitude of the rudder angle should not exceed 5 degrees.

[0070] The approach distance during the test should be sufficiently long to ensure that the vessel reaches a stable state before each test begins (COMEX). During the approach, the vessel should maintain its compass heading and minimize rudder angle. To verify that the vessel has reached a stable state, measurements of shaft speed, shaft torque, and vessel speed at the control positions should be monitored. When all three values ​​are stable, the vessel's condition should be considered "stable."

[0071] Conduct the experiment according to the following steps.

[0072] a) At the start of the test, confirm that the test environment conditions are within the specified range;

[0073] b) Confirm that the wind-powered propulsion device is in an unused condition;

[0074] c) Passing the approach phase while maintaining the same course;

[0075] d) Prepare to begin all measurements;

[0076] e) Once torque, speed, and heading are stable, begin the test and record data for at least 10 minutes.

[0077] f) Determine the data required to obtain WPSFM;

[0078] g) Activate the wind-powered booster to bring it into operating condition;

[0079] h) Repeat steps c) to f);

[0080] i) Navigating a vessel with a rudder angle not exceeding 5° to change the relative wind direction angle;

[0081] j) Repeat steps b) to i) to obtain at least 5 test data of relative wind direction angle, and the test ends.

[0082] Data collection

[0083] During the test, it is crucial to accurately record the relationship between the ship's speed and power.

[0084] In addition, because the speed and power characteristics of ships are extremely sensitive to factors such as wind speed, wind direction, current speed, current direction, and water depth, it is necessary to accurately quantify the boundary conditions. Therefore, these factors should be monitored and recorded as much as possible.

[0085] During the experiment, two types of data acquisition should be used: automatic acquisition via a data acquisition system (measurement computer) and manual recording of information via a log sheet. The goal should always be to record as many parameters as possible via the measurement computer to improve the accuracy of the experiment.

[0086] At the end of each run, the data acquisition system should be able to present the history of all recorded times for all recorded parameters to assess the quality and consistency of the acquired experimental data and store it for subsequent graphical display.

[0087] The data acquisition system should:

[0088] a) Record all available parameters simultaneously;

[0089] b) Time tracking is performed at a sampling rate of at least 1 Hz;

[0090] c) Calculate statistical data (mean, minimum, maximum, and standard deviation).

[0091] In addition, the acquisition system should provide the following values ​​for each measurement data:

[0092] d) Test start time.

[0093] e) The number of samples collected.

[0094] f) Average value.

[0095] g) Standard deviation

[0096] h) Test end time.

[0097] Analysis process

[0098] This analysis includes methods for correcting environmental impacts during the experiment, which can be found in the following reference.

[0099] The method used depends on the situation and available data. A flowchart is shown below. Figure 2 As shown.

[0100] After successively removing the influence of superstructure wind load on power and the influence of current and shallow water on speed from the data of each measurement cycle obtained when the wind booster is not in use, the speed-power curve P0-V0 in the windless, currentless, and deep water conditions is obtained.

[0101] Then, the effects of wind, current, and water depth on the superstructure under the operating conditions of the wind-powered propulsion device are reversed to obtain a new speed-power curve P1-V1. Assuming there is a ship identical to the test vessel but without the wind-powered propulsion device, its speed-power curve is P1-V1.

[0102] The power at a given speed is obtained by interpolating the speed V obtained from the operating condition test of the wind-powered booster onto the P1-V1 curve. The difference between this power and the power obtained from the non-operating condition test of the wind-powered booster is then multiplied by the propulsion efficiency at speed V in the model test report. This yields the boost power provided by the wind-powered booster.

[0103] The analysis of the experiment should include:

[0104] a) Evaluate the acquired data;

[0105] b) Analyze the changes in speed and power caused by wind when the wind-powered propulsion device is not in use;

[0106] c) Analyze the changes in speed and power caused by the downstream flow when the wind-powered booster is not in use;

[0107] d) Analyze the power increase caused by the shallow water effect when the wind-powered booster is not in use;

[0108] e) Analyze the changes in speed and power caused by wind under the operating conditions of the wind-powered propulsion device;

[0109] f) Analyze the changes in speed and power caused by the downstream flow under the operating conditions of the wind-powered propulsion device;

[0110] g) Analyze the power increase caused by the shallow water effect under the operating conditions of the wind-powered booster;

[0111] h) Analyze the power reduction caused by the wind-powered booster;

[0112] i) Introduce the intermediate analysis and final results.

[0113] Result Processing

[0114] After the experiment is completed, the measurement data should be processed in the following order:

[0115] a) Derive the average values ​​of the parameters measured in each test cycle, such as Psi, Vsi, etc. (i≥5) for the wind-powered propulsion system not in use, and Poi, Voi, etc. (i≥5) for the wind-powered propulsion system in use. The ship speed is derived from the interval between the start and end positions and the time elapsed during high-speed travel.

[0116] b) For the unused wind-powered propulsion device in each test cycle, the speed-power curve P0-V0 of the target ship under the conditions of no wind, no current and deep water is obtained by correcting the measured wind speed parameters, calculated flow parameters and measured water depth parameters.

[0117] c) The average wind speed, flow, and shallow water effects on velocity power measured in the operating conditions of the wind booster in each measurement cycle are corrected to P0-V0 in opposite ways to obtain the curve Pi-Vi (i≥5).

[0118] d) Interpolate the average speed Voi measured in the operating conditions of the wind-powered booster on the Pi-Vi curve to obtain the corresponding power Poi'. Calculate the difference between the measured power Poi and the power Poi' obtained from the test of the wind-powered booster in the operating conditions to obtain ΔPi under a certain measurement period. This ΔPi is the boost power corresponding to the relative wind direction angle under the operating conditions of the wind-powered booster.

[0119] e) Calculate the propulsion efficiency ηDi of the corresponding Voi through the model test report. Then the thrust Fi generated by the wind-powered booster under the operating conditions can be calculated as: Fi=△Pi×ηDi / Voi / A, where A is the area of ​​the sail.

[0120] f) Based on the wind tunnel test or CFD test report of the wind booster, the thrust Fi provided by the wind booster under the operating conditions is dimensionless to obtain the dimensionless coefficient ε corresponding to different wind direction angles.

[0121] g) The least squares method is used to calculate the weight between the dimensionless coefficient ε and the dimensionless curve obtained from wind tunnel tests or CFD under different wind direction angles during the operation of the wind-powered booster.

[0122] This weight can be used as a coefficient for subsequent energy efficiency evaluation of wind-powered booster devices. That is, it is a dimensionless coefficient curve obtained by scaling up or down the CFD proportionally.

Claims

1. A method for verifying sail force matrix through sea trials, characterized in that, The ship begins navigation in the test area, keeping its bow unchanged during each measurement cycle. After one measurement cycle, the ship's relative wind direction angle is changed, and the next measurement cycle begins. There are at least 5 measurement cycles, with the relative wind direction angle step sizes falling on (20°, 50°], (50°, 80°], (80°, 110°], (110°, 140°], and (140°, 180°], respectively. The test begins, confirming that the test environment conditions are within the specified range and that the wind booster is in an unused condition. The approach phase is completed while the course remains unchanged. Prepare to begin all measurements, using two types of data acquisition: one for automatic data acquisition through a data acquisition system and the other for manual recording of information using a log sheet. When the torque, speed and heading are stable, start the test and record data for at least 10 minutes to ensure that the data required for WPSFM is obtained. During the operation of WPSFM, conduct environmental observations, turn on the wind booster to bring it into operating condition, navigate the ship with a rudder angle of no more than 5°, change the relative wind angle, and obtain test data of the relative wind angle at least 5 times. The test ends. After the experiment is completed, the measurement data should be processed in the following order: a) Derive the average values ​​of the parameters measured in each test cycle, including the ship's power Psi and speed Vsi, i≥5 when the wind-powered propulsion device is not in use, and the ship's power Poi and speed Voi, i≥5 when the wind-powered propulsion device is in use. The ship's speed is derived from the interval between the start and end positions and the time elapsed during rapid travel. b) For the wind-powered propulsion device not being used in each test cycle, the target ship's speed-power curve P0-V0 is obtained by correcting the measured wind speed parameters, calculated flow parameters, and measured water depth parameters. P0-V0 is the speed-power curve under calm, shallow water conditions; c) The average wind speed, flow, and shallow water effects on velocity power measured in the operating conditions of the wind booster in each measurement cycle are corrected to P0-V0 in opposite ways to obtain the curve Pi-Vi, i≥5. d) Interpolate the average speed Voi measured in the operating conditions of the wind-powered booster on the Pi-Vi curve to obtain the corresponding power Poi'. Calculate the difference between the power Poi measured and Poi' obtained from the test of the wind-powered booster in the operating conditions to obtain ΔPi under a certain measurement period. This ΔPi is the boost power corresponding to the relative wind direction angle under the operating conditions of the wind-powered booster. e) Calculate the propulsion efficiency ηDi of the corresponding Voi through the model test report. Then the thrust Fi generated by the wind-powered booster under the operating conditions can be calculated as: Fi=△Pi×ηDi / Voi / A, where A is the area of ​​the sail. f) Based on the wind tunnel test or CFD test report of the wind booster, the thrust Fi provided by the wind booster under the operating conditions is dimensionless to obtain the dimensionless coefficient ε corresponding to different wind direction angles. g) The weights between the dimensionless coefficient ε and the dimensionless curves obtained from wind tunnel tests or CFD under different wind direction angles are calculated using the least squares method. This weight can be used as a coefficient for subsequent energy efficiency evaluation of wind-powered booster devices, i.e., the dimensionless coefficient curve obtained by scaling up or down the CFD proportionally.

2. The method for verifying the sail force matrix through sea trials according to claim 1, characterized in that, During the test, the environmental impact was corrected by removing the influence of the superstructure wind load on the power and the influence of current and shallow water on the speed from the data of each measurement cycle obtained under the condition that the wind booster was not in use. The speed-power curve P0-V0 under the conditions of no wind, no current and deep water was obtained. Then, the effects of wind, current and water depth on the superstructure under the operating conditions of the wind-powered propulsion device are reversed to P0-V0, resulting in a new speed-power curve P1-V1; assuming there is a ship identical to the test ship but without the wind-powered propulsion device, its speed-power curve is P1-V1. The power at a given speed is obtained by interpolating the speed V obtained from the operating condition test of the wind-powered booster onto the P1-V1 curve. The difference between this power and the power obtained from the non-operating condition test of the wind-powered booster is then multiplied by the propulsion efficiency at speed V in the model test report. This yields the boost power provided by the wind-powered booster.

3. The method for verifying the sail force matrix through sea trials according to claim 1, characterized in that, At the end of each run, the data acquisition system should be able to present the history of all recorded times for all recorded parameters to assess the quality and consistency of the acquired experimental data and store it for subsequent graphical display.

4. The method for verifying the sail force matrix through sea trials according to claim 1, characterized in that, The wind speed-related parameters are relative wind direction and relative wind speed.

5. A method for verifying the sail force matrix through sea trials according to claim 1 or 3, characterized in that, The data acquisition system is a measurement computer.

6. The method for verifying the sail force matrix through sea trials according to claim 1, characterized in that, The wind speed used in the test is one that can clearly provide changes in shaft power, and is no greater than Beaufort scale 10. The duration of the wind speed is sufficient to cover the entire test cycle. The sea state is no greater than level 8. The test area is not obstructed by small boats or commercial traffic.

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