A method for predicting thrust characteristics and turning angle control of a single sail of a sail-assisted ship

Abstract

A method for predicting the thrust characteristics of a single sail of a sail-assisted ship and controlling the turning angle, first defining a single sail thrust characteristics prediction related coordinate system, defining the sail coordinate system to characterize the wind attack angle β of the sail and the single sail aerodynamic characteristics of the sail, and defining the ship coordinate system to characterize the relative wind direction angle α and the sail turning angle θ, determining the sail aerodynamic characteristics matrix when evaluating the sail thrust characteristics, and finally determining the sail thrust characteristics prediction and turning angle. In view of the complex sail thrust characteristics prediction process, the present invention provides a standardized airfoil sail single sail thrust characteristics evaluation process and method with clear logic, predicts the maximum thrust effect of a given sail device with certain aerodynamic characteristics on a ship, accurately identifies the factors affecting the sail thrust characteristics, evaluates the sail thrust characteristics in the sail surface design stage, and provides a basis for the thrust characteristics performance evaluation and airfoil optimization selection between different sail types.

Description

Technical Field

[0001] The present invention belongs to the field of offshore sailing ship design and construction, and in particular relates to a method for predicting the thrust characteristics of a single sail of a sail-assisted ship and controlling the turning angle. Background Art

[0002] Modern wind-sail propulsion systems have become a key component of the green development of ocean-going vessels. The aerodynamic effects of airfoil sails directly impact the overall propulsion performance after installation. Accurately and efficiently evaluating the propulsion characteristics of airfoil sails and optimizing their design based on this performance is a key step in the industrialization and promotion of wind-sail propulsion.

[0003] There is currently no standard process and method for evaluating the sail thrust characteristics based on the aerodynamic characteristics of a single sail. It is necessary to provide a standardized method to accurately and efficiently evaluate the sail thrust characteristics, and to formulate a sail angle control strategy based on the optimal thrust characteristics to provide guidance for the actual ship application of sail-assisted ships. Summary of the Invention

[0004] The present invention provides a method for predicting the thrust characteristics of a single sail of a sail-assisted ship and controlling the turning angle. The technical solution and specific method adopted are as follows:

[0005] Step 1: Define the relevant coordinate system for single sail thrust characteristic prediction.

[0006] In order to accurately predict the thrust characteristics of the sail device, two coordinate systems need to be defined, namely the sail coordinate system and the ship coordinate system.

[0007] Step 101: Define a sail coordinate system to represent the wind attack angle β of the sail and the aerodynamic characteristics of a single sail, denoted as Coor.o'.

[0008] Coordinate origin o': is taken as the intersection of the axis of the sail width direction and the axis of symmetry.

[0009] The x-axis is along the width of the sail, with positive values ​​to the right.

[0010] The y-axis is perpendicular to the axis and points to the convex surface.

[0011] The z-axis is along the height of the sail, with upwards being positive.

[0012] The wind attack angle β is defined as the angle between the wind direction and the x-axis in the sail coordinate system. β ranges from [0°, 180°] and rotates counterclockwise around the y-axis.

[0013] Step 102: Define a ship coordinate system to represent the relative wind direction angle α and the sail turning angle θ, denoted as Coor.0.

[0014] Coordinate origin 0: Taken as the intersection of the ship's stern perpendicular, the mid-longitudinal section and the baseline.

[0015] X-axis: longitudinal axis, with the positive direction pointing from the stern to the bow.

[0016] Y-axis: transverse axis, the positive direction is from the centerline of the ship to the port side.

[0017] Z axis: vertical axis, the positive direction is perpendicular to the XY plane and upward.

[0018] The sail-assisted ship's relative wind direction angle α is defined as the angle between the wind direction and the ship's heading, with clockwise rotation being positive, αϵ [0°, 360°]. When the ship's bow is facing the wind, α = 0°.

[0019] The sail angle θ refers to the angle that 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 value range of θ is [-90°, +90°].

[0020] Step 2: Determine the sail aerodynamic characteristic matrix for sail thrust characteristic evaluation.

[0021] The aerodynamic characteristics of the sail device are obtained based on single sail aerodynamic analysis or model tests and are represented by dimensionless coefficient matrices Cn and Ct.

[0022] Cn is the normal force coefficient matrix perpendicular to the sail axis in the sail coordinate system.

[0023] Ct is the dimensionless axial force coefficient matrix along the axial direction of the sail in the sail coordinate system.

[0024] The normal force coefficient Cn and the axial force coefficient Ct vary with the wind attack angle β, and the sail aerodynamic matrix is ​​obtained, as shown in the following table, where the value range of β is [0°, 180°], and the value range of the wind attack angle interval △β is [1°, 10°].

[0025]

[0026] Step 3: Predict sail thrust characteristics and determine the turning angle.

[0027] Step 301: Determine a feasible sail angle θ range [θ_liml, θ_limr] for each relative wind direction angle α, so that a thrust force can be generated along the length direction of the ship within the sail angle range, and calculate the effective sail angle matrix interval.

[0028] The relative wind direction angle α ranges from [0°, 360°), and the i-th relative wind direction angle is denoted as α i .

[0029] The interval △α between the relative wind direction angles is set to 1°, with a total of 360 relative wind direction angles. i The corresponding relative wind direction angle is i.

[0030] θ_liml represents the left limit of the sail turning angle corresponding to the relative wind direction angle α, and θ_limr represents the right limit of the sail turning angle corresponding to the relative wind direction angle.

[0031] Relative wind direction angle α i ∈[ 0°, 180°], the left limit θi_liml=-90°, the right limit θi_limr= -90°+α i .

[0032] Relative wind direction angle α i ∈(180°,360°), the left limit θi_liml=α i -270°, right limit θi_limr = 90°.

[0033] θi_liml represents the relationship with α i The corresponding sail angle left limit, θi_limr represents the difference between α i The corresponding right limit of the sail turning angle.

[0034] Relative wind direction angle α i The corresponding number of feasible sail turning angles is θi_limr~θi_liml+1. The effective sail turning angle limit matrix is ​​obtained as shown in the following table:

[0035]

[0036] The sail angle θij is set at an interval of △θij of 1°, and the effective sail angle matrix is ​​shown in the following table:

[0037]

[0038] Step 302: For each relative wind direction angle α i , traverse each effective sail turning angle, calculate the corresponding wind attack angle β_newij, and obtain the two-parameter two-dimensional matrix of β_new, as shown in the following table:

[0039]

[0040] Among them, β_newij represents the relative wind direction angle α i and its corresponding wind attack angle under the jth relative sail turning angle θij.

[0041] The wind attack angle β_newij can be calculated by the following formula: β_newij=270°+△θij-αi.

[0042] Step 303: The calculated two-parameter two-dimensional matrix of wind attack angle β_new is combined with the single sail aerodynamic characteristic matrices Cn and Ct for interpolation calculation to obtain the normal force coefficient matrix Cn_new and the axial force coefficient matrix Ct_new corresponding to the wind attack angle β_new.

[0043] Relative wind direction angle α i The normal force coefficient matrix corresponding to the downwind attack angle β_newij is recorded as Cn_newij, and the axial force coefficient is recorded as Ct_newij.

[0044] The interpolation algorithm uses quadratic spline interpolation to ensure engineering accuracy.

[0045] Step 304: For each relative wind direction angle α i , the sail angle θij, based on the sail aerodynamic matrix obtained in the above step 303, further calculate the thrust coefficient matrix fx in the hull coordinate.

[0046] Relative wind direction angle α i The thrust coefficient corresponding to the downwind sail angle θij is recorded as fxij and is calculated by the following formula:

[0047] fxij=Cn_newij×cos(θij)-Ct_newij×sin(θij).

[0048] Step 305: For the relative wind direction angle α i , traverse the sail thrust coefficient fxij corresponding to each sail turning angle θij, and get the maximum thrust coefficient fxi to characterize the sail thrust characteristics under the relative wind direction angle. The corresponding sail turning angle is the sail control turning angle θ controli .

[0049] Traverse all relative wind direction angles to obtain the sail thrust coefficient matrix fx and the sail angle control matrix θ control .

[0050] The beneficial effects of the present invention are:

[0051] 1. Aiming at the complex sail thrust characteristic prediction process, the present invention provides a standardized single-sail thrust characteristic evaluation process and method for aerofoils with clear logic, which can predict the maximum thrust effect generated by a given sail device with certain aerodynamic characteristics on a ship.

[0052] 2. The optimal sail control angle formulated by the present invention based on the maximum thrust effect can be used to guide the design of actual ship control strategies and actual ship applications.

[0053] 3. The present invention accurately identifies the factors that affect the thrust characteristics of the sail. Through regression analysis, the relative wind direction angle interval is taken as 1.0°, and the relative sail rotation angle interval is taken as 1.0°. This can achieve accurate and efficient thrust characteristic prediction and meet the engineering prediction needs.

[0054] 4. The thrust prediction method of the sail device provided by the present invention can evaluate the thrust characteristics of the sail during the sail surface design stage, providing a basis for the thrust characteristic performance evaluation and airfoil optimization selection between different sail types. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is the definition of sail coordinate system and the schematic diagram of wind attack angle;

[0056] Figure 2 It is the definition of the ship coordinate system and the schematic diagram of the sail turning angle;

[0057] Figure 3 is the sail angle control matrix θ control . DETAILED DESCRIPTION

[0058] The present invention will be further described with reference to the accompanying drawings.

[0059] Step 1: Define the relevant coordinate system for single sail thrust characteristic prediction.

[0060] Winged sails have significant aerodynamic effects, which vary significantly with wind angles of attack, sail size, and sail airfoil. Therefore, aerodynamic characteristics must be described within the sail's own coordinate system. The propulsion provided by a sail to a ship is also directly affected by wind direction. Therefore, the aerodynamic effects in the sail coordinate system must be converted to the ship's length to truly reflect the thrust effect. Therefore, to accurately predict the thrust characteristics of a single sail, two coordinate systems must be defined: the sail coordinate system and the ship coordinate system.

[0061] 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'. The coordinate origin o' is taken as the intersection of the sail width axis and the symmetry axis.

[0062] The x-axis is along the width of the sail, with positive values ​​to the right.

[0063] The y-axis is perpendicular to the axis and points to the convex surface.

[0064] The z-axis is along the height of the sail, with upwards being positive.

[0065] The wind attack angle β is defined as the angle between the wind direction and the x-axis in the sail coordinate system; the range of β is [0°, 180°], rotating counterclockwise around the y-axis, such as Figure 1 shown.

[0066] Step 102: Define a ship coordinate system to represent the relative wind direction angle α and the sail turning angle θ, denoted as Coor.0.

[0067] Coordinate origin 0: Taken as the intersection of the ship's stern perpendicular, the mid-longitudinal section and the baseline.

[0068] X-axis: longitudinal axis, with the positive direction pointing from the stern to the bow.

[0069] Y-axis: transverse axis, the positive direction is from the centerline of the ship to the port side.

[0070] Z axis: vertical axis, the positive direction is perpendicular to the XY plane and upward.

[0071] The relative wind direction angle α of the sail-assisted ship is defined as the angle between the direction of the wind and the bow direction, with clockwise rotation being positive, α∈[0°, 360°); when the bow is facing the wind, α=0°.

[0072] The sail angle θ refers to the angle that 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 value range of θ is [-90°, +90°].

[0073] Single sail thrust characteristic prediction, ship speed is set to 0, such as Figure 2 shown.

[0074] Step 2: Determine the sail aerodynamic characteristic matrix for sail thrust characteristic evaluation.

[0075] The purpose of evaluating the thrust characteristics of a single wing-shaped sail is to predict the thrust characteristics of a sail that assists ship propulsion in operation, and to provide the maximum thrust to the ship by finding the optimal turning angle of the sail at each relative wind direction angle.

[0076] The aerodynamic characteristics of the sail device are obtained based on single sail aerodynamic analysis or model tests.

[0077] The aerodynamic characteristics of a specific sail operating state are characterized by the dimensionless coefficient matrices Cn and Ct.

[0078] Cn is the normal force coefficient matrix perpendicular to the sail axis in the sail coordinate system.

[0079] Ct is the dimensionless axial force coefficient matrix along the axial direction of the sail in the sail coordinate system.

[0080] The normal force coefficient Cn and the axial force coefficient Ct vary with the wind attack angle β. The sail aerodynamic matrix is ​​expressed as follows, where the value range of β is [0°-180°] and the value range of the wind attack angle interval △β is [1°, 10°].

[0081] In this embodiment, the normal force coefficient matrix Cn and the axial force coefficient matrix Ct at various wind attack angles are obtained through numerical analysis. The wind attack angle interval Δβ is taken as 10°. The sail aerodynamic characteristic matrix is ​​shown in the following table:

[0082]

[0083] Step 3: Predict sail thrust characteristics and determine the turning angle.

[0084] Step 301: Determine a feasible sail angle θ range [θ_liml, θ_limr] for each relative wind direction angle α, so that thrust can be generated along the ship length direction within the sail angle range, and calculate the effective sail angle matrix interval.

[0085] The relative wind direction angle α ranges from [0°, 360°), and the i-th relative wind direction angle is denoted as α i。

[0086] The interval △α between the relative wind direction angles is taken as 1°, with a total of 360 relative wind direction angles; α i The corresponding relative wind direction angle is i.

[0087] θ_liml represents the left limit of the sail turning angle corresponding to the relative wind direction angle α, and θ_limr represents the right limit of the sail turning angle corresponding to the relative wind direction angle.

[0088] Relative wind direction angle α i ∈[ 0°, 180°], the left limit θi_liml=-90°, the right limit θi_limr= -90°+α i。

[0089] Relative wind direction angle α i ∈(180°,360°), the left limit θi_liml=α i -270°, right limit θi_limr = 90°.

[0090] θi_liml represents the relationship with α i The corresponding sail angle left limit, θi_limr represents the difference between α i The corresponding right limit of the sail turning angle.

[0091] In this embodiment, in order to more concisely and clearly reflect the entire calculation process, the relative wind direction angle interval Δα is taken as 10°, and the effective sail turning angle limit matrix and the number of feasible sail turning angles n_θ are shown in the following table:

[0092]

[0093] In this embodiment, in order to more concisely and clearly reflect the entire calculation process, the interval Δθij of the sail angle θij is 10°, and the effective sail angle matrix obtained is shown in the following table:

[0094]

[0095] Step 302: For each relative wind direction angle α i , traverse each effective sail turning angle, calculate the corresponding wind attack angle β_newij, and obtain the two-parameter two-dimensional matrix of β_new.

[0096] The wind attack angle β_newij can be calculated by the following formula: β_newij=270+θij-α i。

[0097] Wind attack angle α i The corresponding number of feasible sail turning angle intervals is θi_limr~θi_liml+1.

[0098] According to the above formula, the wind attack angle β_new matrix calculated in this embodiment is shown in the following table:

[0099]

[0100] Step 303: The calculated two-parameter two-dimensional matrix of wind attack angle β_new is combined with the single sail aerodynamic characteristic matrices Cn and Ct for interpolation calculation to obtain the normal force coefficient matrix Cn_new and the axial force coefficient matrix Ct_new corresponding to the wind attack angle β_new.

[0101] Relative wind direction angle α i The normal force coefficient matrix corresponding to the downwind attack angle β_newij is recorded as Cn_newij, and the axial force coefficient is recorded as Ct_newij.

[0102] The interpolation algorithm uses quadratic spline interpolation to ensure engineering accuracy.

[0103] In this embodiment, the calculated Cn_new matrix is ​​shown in the following table:

[0104]

[0105] In this embodiment, the calculated Ct_new matrix is ​​shown in the following table:

[0106]

[0107] Step 304: For each relative wind direction angle α i , the sail angle θij, based on the sail aerodynamic matrix obtained in the above step 303, further calculate the thrust coefficient matrix fx in the hull coordinate.

[0108] Relative wind direction angle α i The thrust coefficient corresponding to the downwind sail angle θij is recorded as fxij and is calculated by the following formula: fxij=Cn_newij×cos(θij)-Ct_newij×sin(θij).

[0109] In this embodiment, the thrust coefficient matrix is ​​calculated as shown in the following table:

[0110]

[0111] Step 305: For the relative wind direction angle α i , traverse the sail thrust coefficient fxij corresponding to each sail turning angle θij, and get the maximum thrust coefficient fxi to characterize the sail thrust characteristics under the relative wind direction angle. The corresponding sail turning angle is the sail control turning angle θ controli .

[0112] Traverse all relative wind direction angles to obtain the sail thrust coefficient matrix fx and the sail angle control matrix θ control .

[0113] The sail thrust coefficient matrix fx and sail rotation angle control matrix θ finally obtained in this embodiment control As shown in the following table, Figure 3 As shown:

[0114]

[0115] The calculation results of this embodiment show that the sail cannot generate thrust between [0°, 20°) and (340°, 360°]. When the wind comes in this relative wind direction angle range, the sail needs to be set in the windproof state to reduce the resistance to the ship.

Claims

1. A method for predicting thrust characteristics and controlling the turning angle of a single sail of a sail-assisted ship, characterized in that: The specific method is as follows: Step 1: Define the relevant coordinate system for single sail thrust characteristics prediction In order to accurately predict the thrust characteristics of the sail device, two coordinate systems need to be defined, namely the sail coordinate system and the ship coordinate system; Step 101: Define the sail coordinate system to characterize the wind attack angle β of the sail and the aerodynamic characteristics of the sail, denoted as Coor.o'. Coordinate origin o': taken as the intersection of the sail width axis and the symmetry axis; The x-axis is along the sail width axis, with positive values ​​to the right; The y-axis is perpendicular to the axis direction and points to the convex surface as positive; The z axis is along the direction of the sail height, with upward being positive; The wind attack angle β is defined as the angle between the wind direction and the x-axis in the sail coordinate system; the range of β is [0°, 180°], rotating counterclockwise around the y-axis; Step 102: define a ship coordinate system to represent the relative wind direction angle α and the sail turning angle θ, denoted as Coor.0; Coordinate origin 0: taken as the intersection of the ship's stern perpendicular, the mid-longitudinal section and the baseline; X-axis: longitudinal axis, the positive direction is from the stern to the bow; Y axis: transverse axis, the positive direction is from the centerline of the ship to the port side; Z axis: vertical axis, the positive direction is perpendicular to the XY plane upward; The relative wind direction angle α of the sail-assisted ship is defined as the angle between the wind direction and the bow direction, with clockwise rotation being positive, αϵ [0°, 360°); when the bow is facing the wind, α=0°; The sail turning angle θ refers to the angle of rotation of the y-axis of the sail coordinate system relative to the x-axis of the ship coordinate system. Clockwise rotation is positive, counterclockwise rotation is negative, and the value range of θ is [-90°, +90°]; Step 2: Determine the sail aerodynamic matrix for sail thrust characteristics evaluation 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 axial direction of the sail surface in the sail coordinate system; Ct is the dimensionless axial force coefficient matrix along the axial direction of the sail surface in the sail coordinate system; The normal force coefficient Cn and the axial force coefficient Ct change with the wind attack angle β, and the sail aerodynamic matrix table is obtained, where the value range of β is [0°, 180°], and the value range of the wind attack angle interval △β is [1°, 10°]; Step 3: Prediction of sail thrust characteristics and determination of turning angle Step 301: determining a feasible sail angle θ range [θ_liml, θ_limr] for each relative wind direction angle α, so that a thrust force can be generated in the direction of the ship length within the sail angle range, and calculating an effective sail angle matrix interval; 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 △α between the relative wind direction angles is taken as 1°, with a total of 360 relative wind direction angles; α i The corresponding relative wind direction angle is i; θ_liml represents the left limit of the sail turning angle corresponding to the relative wind direction angle α, and θ_limr represents the right limit of the sail turning angle corresponding to the relative wind direction angle; Relative wind direction angle α i ∈[ 0°, 180°], the left limit θi_liml=-90°, the right limit θi_limr= -90°+α i ; Relative wind direction angle α i ∈(180°,360°), the left limit θi_liml=α i -270°, right limit θi_limr = 90°; θi_liml represents the relationship with α i The corresponding sail angle left limit, θi_limr represents the difference with α i The corresponding right limit of the sail turning angle; Relative wind direction angle α i The corresponding number of feasible sail turning angles is θi_limr~θi_liml+1; the effective sail turning angle limit matrix is ​​obtained; The interval △θij of the sail turning angle θij is 1°, and the effective sail turning angle matrix is ​​obtained; Step 302: For each relative wind direction angle α i , traverse each effective sail turning angle, calculate the corresponding wind attack angle β_newij, and obtain the two-parameter two-dimensional matrix of β_new; Among them, β_newij represents the relative wind direction angle α i and its corresponding wind attack angle under the jth relative sail turning angle θij; The wind attack angle β_newij can be calculated by the following formula: β_newij=270+θij-α i ; Step 303: The calculated two-parameter two-dimensional matrix of the wind attack angle β_new is combined with the single sail aerodynamic characteristic matrices Cn and Ct for interpolation calculation to obtain the normal force coefficient matrix Cn_new and the axial force coefficient matrix Ct_new corresponding to the wind attack angle β_new; Relative wind direction angle α i The normal force coefficient matrix corresponding to the downwind attack angle β_newij is recorded as Cn_newij, and the axial force coefficient is recorded as Ct_newij; The interpolation algorithm uses quadratic spline interpolation to ensure engineering accuracy; Step 304: For each relative wind direction angle α i , the sail angle △θij, based on the sail aerodynamic matrix obtained in the above step 303, further calculate the thrust coefficient matrix fx in the hull coordinates; Relative wind direction angle α i The thrust coefficient corresponding to the downwind sail turning angle △θij is recorded as fxij and is calculated by the following formula: fxij=Cn_newij×cos(θij)-Ct_newij×sin(θij) Step 305: For the relative wind direction angle α i , traverse the sail thrust coefficient fxij corresponding to each sail turning angle △θij, and get the maximum thrust coefficient fxi to characterize the sail thrust characteristics under the relative wind direction angle. The corresponding sail turning angle is the sail control turning angle △θ controli ; Traverse all relative wind direction angles to obtain the sail thrust coefficient matrix fx and the sail angle control matrix θ control .

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