A method for modifying the line shape of a surface ship's deflector

Abstract

The present application discloses a method for modifying the line shape of a surface ship shroud, which relates to the field of ship technology. The method comprises: establishing a deformation control domain and uniformly discretizing it into multiple discrete points; determining the displacement values ​​of the discrete points on the missing top surface, bottom surface, mid-longitudinal surface, and side surface of the semi-ellipsoid of the deformation control domain according to the line shape modification requirements; constructing a Laplace displacement equation based on the line shape modification requirements with the minimum gradient of the displacement values ​​of all discrete points, and solving the Laplace displacement equation using the displacement values ​​of the discrete points to obtain the displacement values ​​of other discrete points; using NURBS functions and interpolation algorithms to interpolate the displacement values ​​of each discrete point to obtain the displacement value of any surface control point of the shroud to be deformed and perform line shape modification to obtain the modified line shape. The method of the present application can quickly generate a smooth shroud shape, thereby improving the efficiency of shroud optimization design and modeling.

Description

Technical Field

[0001] The present application relates to the field of ship technology, and in particular to a method for modifying the line shape of a surface ship's fairing. Background Art

[0002] The surface ship fairing refers to the approximately spherical structure at the front of the bow below the designed waterline of the ship. The surface ship fairing helps to reduce the resistance on the hull and thus improve the speed of the ship's navigation. However, the cavitation phenomenon in the surface ship fairing will also increase the ship's noise and thus affect the ship's noise level.

[0003] The influence of the surface ship shroud on the comprehensive performance of the ship is mainly related to the line shape of the surface ship shroud and the coupling between it and the main body of the ship must also be considered. Therefore, it is necessary to optimize the line shape of the surface ship shroud to optimize the comprehensive performance of the ship as much as possible. In the process of optimizing the line shape of the surface ship shroud, it is necessary to modify the line shape of the surface ship shroud frequently to evaluate the impact of different line shapes on the comprehensive performance of the ship. The current method of modifying the line shape of the surface ship shroud is mainly to use general 3D CAD software to manually adjust point by point. This method has low modification efficiency and it is difficult to ensure the most basic smoothness requirements of the modified line shape, resulting in a cumbersome and inefficient design process, which affects the design efficiency of the surface ship shroud. Summary of the Invention

[0004] In response to the above-mentioned problems and technical requirements, this application proposes a method for modifying the line shape of a surface ship deflector. The technical solution of this application is as follows:

[0005] A method for modifying the line shape of a surface ship deflector, comprising the following steps:

[0006] A deformation control domain is established based on the shroud to be deformed. The deformation control domain is a semi-ellipsoid with a missing top and encloses the shroud to be deformed. The long semi-axis of the deformation control domain is along the ship length, the horizontal semi-axis is along the ship width, and the vertical semi-axis is along the ship height.

[0007] Uniformly discretize the deformation control domain to obtain multiple discrete points;

[0008] Determine the displacement values ​​of discrete points on the missing top surface, bottom surface, mid-longitudinal surface, and side surface of the semi-ellipsoid of the deformation control domain according to the requirements of line type modification; the bottom surface of the deformation control domain is the plane where the horizontal semi-axis and the vertical semi-axis are located and is perpendicular to the major semi-axis direction; the missing top surface of the deformation control domain is parallel to the bottom surface of the deformation control domain; the mid-longitudinal surface of the deformation control domain is the plane where the major semi-axis and the vertical semi-axis are located and is perpendicular to the horizontal semi-axis;

[0009] A Laplace displacement equation is constructed based on the linear modification requirement of minimizing the gradient of the displacement values ​​of all discrete points in the deformation control domain, and the Laplace displacement equation is solved using the displacement values ​​of the discrete points on the missing top surface, bottom surface, mid-longitudinal surface and side surface of the semi-ellipsoid of the deformation control domain to obtain the displacement values ​​of other discrete points in the deformation control domain;

[0010] The NURBS function and interpolation algorithm are used to interpolate the displacement value of any surface control point of the deformed shroud according to the displacement value of each discrete point in the deformation control domain. The line type of the deformed shroud is modified according to the displacement value of each surface control point to obtain the modified line type that meets the line type modification requirements.

[0011] A further technical solution is to uniformly discretize the deformation control domain to obtain multiple discrete points including:

[0012] The deformation control domain is uniformly discretized along the semi-major axis to obtain n u vertical sections; for each vertical section: divide the vertical section evenly along the horizontal semi-axis direction to obtain n sections including the section where the vertical semi-axis is located. v -2 mutually parallel transverse segments and two curve segments on both sides, each transverse segment and each curve segment are uniformly discretized along the vertical semi-axis direction to obtain n discrete points including those located on the straight line where the horizontal semi-axis is located w discrete points;

[0013] Each vertical section is discretized to obtain n v ×n w discrete points, the deformation control domain is discretized to obtain n u ×n v ×n w The position coordinates of the kth discrete point (i, j, k) from bottom to top on the jth sectional segment starting from the port side on the i-th vertical section starting from the missing top surface in the global coordinate system are marked as (x i ,y j ,z k ); the global coordinate system takes the intersection of the vertical line passing through the front end point of the bow and the bottom surface of the hull as its origin, the positive direction of the x-axis points to the stern, the positive direction of the y-axis points to the starboard, and the positive direction of the z-axis is vertically upward; the major semi-axis direction of the deformation control domain is along the x-axis direction of the global coordinate system, the horizontal semi-axis direction is along the y-axis direction, and the vertical semi-axis direction is along the z-axis direction.

[0014] A further technical solution is to determine the displacement values ​​of discrete points on the missing top surface, bottom surface, mid-longitudinal surface and side surface of the semi-ellipsoid of the deformation control domain according to the line type modification requirements, including:

[0015] When the line type modification requirement indicates that the length of the deformable shroud to be modified along the semi-major axis is modified, the displacement values ​​of all discrete points on the bottom surface of the deformation control domain in the x, y, and z directions are determined to be 0, and the displacement value of all discrete points on the top surface of the deformation control domain in the x direction is determined to be the target length displacement value, and the displacement values ​​in the y and z directions are determined to be 0; when the line type modification requirement indicates that the deformable shroud to be modified to be longer, the target length displacement value is negative; when the line type modification requirement indicates that the deformable shroud to be modified to be shorter, the target length displacement value is positive; the absolute value of the target length displacement value is related to the length change of the deformable shroud to be modified;

[0016] When the line type modification requirement indicates that the width of the deformable shroud is modified along the horizontal semi-axis, the displacement values ​​of all discrete points on the mid-longitudinal surface of the deformation control domain in the x, y and z directions are determined to be 0, and the displacement value of all discrete points on the left side surface of the semi-ellipsoid of the deformation control domain in the y direction is determined to be the target width displacement value, and the displacement values ​​in the x and z directions are determined to be 0; the displacement values ​​of all discrete points on the right side surface of the semi-ellipsoid of the deformation control domain in the y direction are determined to be equal to the displacement values ​​of all discrete points on the left side surface of the semi-ellipsoid and opposite in direction, and the displacement values ​​in the x and z directions are determined to be 0; when the line type modification requirement indicates that the deformable shroud is modified to be wider, the target width displacement value is negative; when the line type modification requirement indicates that the deformable shroud is modified to be narrower, the target width displacement value is positive; the absolute value of the target width displacement value is related to the width change of the deformable shroud; wherein, all discrete points on the left side surface of the semi-ellipsoid include n points on the curved segment close to the port side on each vertical section. w discrete points; all discrete points on the right side of the semi-ellipsoid including the n points on the curved segment close to the starboard side on each vertical section w discrete points;

[0017] When the linear modification requirement indicates that the downward angle of the to-be-deformed shroud is modified along the vertical semi-axis direction, the displacement values ​​of all discrete points on the bottom surface of the deformation control domain in the x-direction, y-direction, and z-direction are determined to be 0, and the displacement value of all discrete points on the top surface of the deformation control domain in the z-direction is determined to be the target downward angle displacement value, and the displacement values ​​in the x-direction and y-direction are 0; when the linear modification requirement indicates that the downward angle of the to-be-deformed shroud is modified to become smaller, the target downward angle displacement value is negative; when the linear modification requirement indicates that the downward angle of the to-be-deformed shroud is modified to become larger, the target downward angle displacement value is positive; the absolute value of the target downward angle displacement value is related to the change in the downward angle of the to-be-deformed shroud; the downward angle represents the angle between the line connecting the lowest point of the to-be-deformed shroud along the z-direction and the lowest point of the surface ship along the z-direction and the x-axis.

[0018] A further technical solution is that constructing the Laplace shift equation includes constructing the Laplace shift equation for any discrete point (i, j, k) as:

[0019]

[0020] Among them, the discrete point (i+1, j, k) is the adjacent discrete point of the discrete point (i, j, k) in the major semi-axis direction, the discrete point (i, j+1, k) is the adjacent discrete point of the discrete point (i, j, k) in the horizontal semi-axis direction, and the discrete point (i, j, k+1) is the adjacent discrete point of the discrete point (i, j, k) in the vertical semi-axis direction; h ix is the distance between discrete points (i, j, k) and discrete points (i+1, j, k) in the direction of the major semi-axis, h iy is the distance between discrete points (i, j, k) and discrete points (i+1, j, k) in the horizontal semi-axis direction, h iz is the distance between the discrete point (i, j, k) and the discrete point (i+1, j, k) in the vertical semi-axis direction; f ijk is the displacement value of the discrete point (i, j, k), f (i+1)jk is the displacement value of the discrete point (i+1,j,k), f (i+2)jk is the displacement value of the discrete point (i+2,j,k), f i(j+1)k is the displacement value of the discrete point (i, j+1, k), f i(j+2)k is the displacement value of the discrete point (i, j+2, k), f ij(k+1) is the displacement value of the discrete point (i, j, k+1), f ij(k+2) is the displacement value of the discrete point (i, j, k+2).

[0021] Its further technical solution is that the target length displacement value is -20% to +50% of the distance between the missing top surface and the bottom surface of the deformation control domain along the x-direction; the target width displacement value is -20% to +40% of the horizontal semi-axis length of the bottom surface of the deformation control domain; and the target downward angle displacement value is -40% to +100% of the vertical semi-axis length of the bottom surface of the deformation control domain.

[0022] A further technical solution is to determine the displacement value of any surface control point of the deflector to be deformed, including:

[0023] Using NURBS functions and interpolation algorithms to construct a linear equation system of interpolation coefficients including unknown interpolation coefficients;

[0024] The interpolation coefficient U in the linear equations is obtained by solving the position coordinates and displacement values ​​of all discrete points in the deformation control domain in the global coordinate system. ijk ;

[0025] The displacement value of the current surface control point is determined according to the position coordinates of any surface control point of the deflector to be deformed in the global coordinate system using the interpolation coefficient linear equation group.

[0026] A further technical solution is that the interpolation coefficient linear equations are:

[0027]

[0028] Among them, S(u,v,w) is the displacement value of any position coordinate (u,v,w) in the global coordinate system, N i,p (u) is the i-th p-order B-spline basis function, N j,q (v) is the j-th q-order B-spline basis function, N k,r (w) is the kth r-order B-spline basis function, Represents the tensor product, and the expression of the B-spline basis function is:

[0029]

[0030] Its further technical solution is to solve the interpolation coefficient linear equations according to the position coordinates and displacement values ​​of all discrete points in the deformation control domain in the global coordinate system to obtain the interpolation coefficient U ijk include:

[0031] The position coordinates (x i ,y j ,z k ) is converted to the corresponding normalized position coordinates (u i ,v j ,w k )and Among them, x max is the maximum value of the x coordinate of all discrete points in the deformation control domain, x min is the minimum value of the x coordinate of all discrete points in the deformation control domain, and y max is the maximum value of the y coordinate of all discrete points in the deformation control domain, y min is the minimum value of the y coordinate of all discrete points in the deformation control domain, z max is the maximum value of the z coordinate of all discrete points in the deformation control domain, z min is the minimum value of the z coordinate of all discrete points in the deformation control domain;

[0032] according to Solve the interpolation coefficient U in the linear equation system ijk , f ijk is the displacement value of the discrete point (i, j, k).

[0033] The beneficial technical effects of this application are:

[0034] The present application proposes a method for modifying the linear shape of a surface ship's shroud, which can fully fit the shroud to be deformed by constructing a deformation control domain of a semi-ellipsoid with a missing top, thereby reducing redundant space within the deformation control domain. The deformation control domain is discretized into multiple discrete points as a whole, and the displacement values ​​of the discrete points on the missing top surface, bottom surface, middle longitudinal surface and side surface of the semi-ellipsoid are specified and interpolated to obtain the displacement value of each surface control point. The surface control points within the entire deformation control domain can be modified, and rapid deformation of the shroud to be deformed along different dimensions such as length, width, and downward angle can be achieved within a specified range. At the same time, it ensures that the deformed shroud has a smooth appearance and a smooth transition with the main body of the ship, thereby enhancing the coupling with the surface ship and helping to improve the overall performance of the surface ship.

[0035] By introducing the Laplace displacement equation and using the NURBS interpolation method to calculate the displacement value of each surface control point, a line shape with minimal displacement gradient change can be obtained. Compared with the traditional FFD method, this application method can generate a smoother deformed shroud line shape. By constructing the Laplace displacement equation for all discrete points and using NURBS functions and interpolation algorithms to establish an interpolation space, the displacement values ​​of all surface control points within the deformation control domain can be calculated at once, improving the efficiency of shroud optimization design and modeling, and helping to obtain a higher-performance smooth shroud shape. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a flow chart of the line type modification method.

[0037] Figure 2 It is the deformation control domain annotation diagram.

[0038] Figure 3 It is a schematic diagram of the established deformation control domain.

[0039] Figure 4 It is a discretization diagram of the deformation control domain.

[0040] Figure 5 It is a schematic diagram of the global coordinate system.

[0041] Figure 6 The linear modification requirement indicates that the length of the deformed fairing along the semi-major axis should be modified.

[0042] Figure 7 The linear modification requirement indicates that the width of the deformed fairing along the horizontal semi-axis direction is modified.

[0043] Figure 8 The linear modification requirement indicates to modify the downward angle of the deformed fairing along the vertical semi-axis direction.

[0044] Figure 9 This is a comparison before and after modifying the length of the air duct.

[0045] Figure 10 This is a comparison before and after modifying the width of the air duct.

[0046] Figure 11 This is a comparison before and after modifying the downward angle of the air shroud. DETAILED DESCRIPTION

[0047] The specific implementation of this application will be further described below with reference to the accompanying drawings.

[0048] This application proposes a method for modifying the line shape of a surface ship deflector, please refer to Figure 1 The specific steps are as follows:

[0049] Step 1: Establish a deformation control domain based on the deflector to be deformed. Since the deflector is installed at the bulbous bow of the surface ship, the front part of the bulbous bow is a protruding, approximately spherical structure. Therefore, in order to design a deflector that fully fits the bulbous bow, a deformation control domain with a topless semi-ellipsoidal structure is established and the deflector to be deformed is wrapped inside. For the specific position structure, please refer to Figure 2 The center line of the deformation control domain is aligned with the center line of the to-be-deformed fairing, and the long semi-axis of the deformation control domain is along the ship length, the horizontal semi-axis is along the ship width, and the vertical semi-axis is along the ship height.

[0050] exist Figure 2 A deformation control domain is constructed at the marked position shown. The missing top surface of the missing top semi-ellipsoid is spaced a certain distance from the front end and bottom of the bow. The spacing is set according to the design requirements of the fairing, for example, 25 mm. The missing top surface and bottom surface of the deformation control domain are both elliptical planes. The bottom surface is the plane where the horizontal semi-axis and the vertical semi-axis are located and is perpendicular to the long semi-axis direction. The missing top surface and bottom surface of the deformation control domain are parallel to each other. The distance between the missing top surface and the bottom surface is the length of the deformation control domain, recorded as l, twice the length of the horizontal semi-axis of the bottom surface is the width of the deformation control domain, recorded as W, and twice the length of the vertical semi-axis of the bottom surface is the height of the deformation control domain, recorded as H. Construct a deformation control domain with a length of l = 1270 mm, a width of W = 960 mm, and a height of H = 460 mm as shown below. Figure 3 As shown in the figure, the red area is the deformation control domain, the hollow circle is the surface control point Pc on the bulbous bow surface, the part wrapped by the deformation control domain is the deformation domain, and the rest is the non-deformation domain. The deformation domain contains all the surface control points of the shroud to be deformed.

[0051] Step 2: Uniformly discretize the deformation control domain to obtain multiple discrete points. Prior art techniques can obtain multiple discrete points by uniformly dividing the outer surface of the deformation control domain. However, this method can only control surface control points near the outer surface of the deformation control domain. This application, however, discretizes the entire deformation control domain to better control surface control points at any location within the deformation control domain.

[0052] In one embodiment, the deformation control domain is uniformly discretized along the semi-major axis to obtain n u For each vertical section: divide the vertical section evenly along the horizontal semi-axis to obtain n sections including the section where the vertical semi-axis is located. v -2 mutually parallel transverse segments and two curve segments on both sides, each transverse segment and each curve segment are uniformly discretized along the vertical semi-axis direction to obtain n discrete points including those located on the straight line where the horizontal semi-axis is located w discrete points. Figure 4 (a) is a schematic diagram of uniformly discretizing a vertical section. It is evenly divided along the horizontal semi-axis to obtain three mutually parallel section segments and two curve segments. The section segment in the middle column is the section segment where the vertical semi-axis is located. Then, each section segment and each curve segment are uniformly discretized into five discrete points along the vertical semi-axis direction. The section segment in the middle row is the straight line where the horizontal semi-axis is located.

[0053] Each vertical section is discretized in the above manner to ensure that the number of discrete points on each vertical section is the same, and n is obtained on each vertical section. v ×n w discrete points, the deformation control domain is discretized to obtain n u ×n v ×n w discrete points, the result after the deformation control domain is discretized is as follows Figure 4 As shown in (b) in the figure. The position coordinates of the kth discrete point (i, j, k) from bottom to top on the jth section segment starting from the port side on the i-th vertical section starting from the missing top surface in the global coordinate system are marked as (x i ,y j ,z k ). Among them, i, j, k are all integers and i∈[1,n u ], j∈[1,n v ], k∈[1,n w ],n u 、n v 、n w The value of can be customized according to the needs. In order to comprehensively consider the calculation accuracy and efficiency, each vertical section is generally discretized into 5 to 10 discrete points. The global coordinate system is as follows Figure 5 As shown in the figure, with the intersection of the vertical line passing through the frontmost point of the bow and the bottom of the hull as the origin, the positive x-axis points to the stern, the positive y-axis points to the starboard side, and the positive z-axis points vertically upward. The major semi-axis of the deformation control domain is along the x-axis of the global coordinate system, the horizontal semi-axis is along the y-axis, and the vertical semi-axis is along the z-axis.

[0054] Step 3: Determine the displacement values ​​of discrete points on the missing top surface, bottom surface, mid-longitudinal surface, and side surfaces of the semi-ellipsoid of the deformation control domain based on the line type modification requirements. The bottom surface of the deformation control domain is the plane containing the horizontal semi-axis and the vertical semi-axis and is perpendicular to the major semi-axis. The missing top surface of the deformation control domain is parallel to the bottom surface of the deformation control domain. The mid-longitudinal surface of the deformation control domain is the plane containing the major semi-axis and the vertical semi-axis and is perpendicular to the horizontal semi-axis. The side surfaces of the semi-ellipsoid of the deformation control domain are the curved surfaces located on both sides of the mid-longitudinal surface along the horizontal semi-axis.

[0055] The linear modification requirement of this application is to modify at least one of the length, width and downward angle of the shroud to be deformed. Modifying the downward angle of the shroud to be deformed can adjust the up and down deformation of the head end of the shroud to be deformed along the vertical semi-axis direction. The downward angle represents the angle between the line connecting the lowest point of the shroud to be deformed along the z direction and the lowest point of the surface ship along the z direction and the x-axis.

[0056] In one embodiment, when the linear modification requirement indicates that the length of the deflector to be deformed along the semi-major axis is modified, fixed constraints are applied to the discrete points on the bottom surface of the deformation control domain, and displacement constraints are applied to the discrete points on the missing top surface of the deformation control domain. The displacement values ​​of all discrete points on the bottom surface of the deformation control domain in the x-direction, y-direction, and z-direction are determined to be 0, and the displacement values ​​of all discrete points on the missing top surface of the deformation control domain in the x-direction are determined to be the target length displacement value, and the displacement values ​​in the y-direction and z-direction are determined to be 0. When the linear modification requirement indicates that the deflector to be deformed is modified to be longer, the target length displacement value is negative; when the linear modification requirement indicates that the deflector to be deformed is modified to be shorter, the target length displacement value is positive; the absolute value of the target length displacement value is related to the length change of the deflector to be deformed. The target length displacement value is set according to the requirements of the line type modification. In this application, the target length displacement value is set to -20% to +50% of the distance (length l) along the x-direction between the missing top surface and the bottom surface of the deformation control domain. That is, the length of the deformed shroud can be lengthened by at most 20% of the length l of the deformed shroud, and can be shortened by at most 50% of the length l of the deformed shroud. For example, if the length of the deformed shroud is lengthened by 30mm, the target length displacement value is -30mm, and the setting of the deformation control domain is as follows: Figure 6 shown.

[0057] When the linear modification requirement indicates that the width of the deformed fairing along the horizontal semi-axis is to be modified, a fixed constraint is applied to the mid-longitudinal surface of the deformation control domain, and a displacement constraint is applied to the side surface of the semi-ellipsoid of the deformation control domain. The displacement values ​​of all discrete points on the mid-longitudinal surface of the deformation control domain in the x, y, and z directions are determined to be 0, and the displacement value of all discrete points on the left side surface of the semi-ellipsoid of the deformation control domain in the y direction is determined to be the target width displacement value, and the displacement values ​​in the x and z directions are determined to be 0; the displacement values ​​of all discrete points on the right side surface of the semi-ellipsoid of the deformation control domain in the y direction are determined to be equal in magnitude and opposite in direction to the displacement values ​​of all discrete points on the left side surface of the semi-ellipsoid of the deformation control domain, and the displacement values ​​in the x and z directions are determined to be 0. When the line type modification requirement indicates that the deformed shroud is to be widened, the target width displacement value is negative; when the line type modification requirement indicates that the deformed shroud is to be narrowed, the target width displacement value is positive; the absolute value of the target width displacement value is related to the width change of the deformed shroud; among them, all discrete points on the left surface of the semi-ellipsoid, including the n points on the curved segment close to the port side on each vertical section, are w discrete points; all discrete points on the right side of the semi-ellipsoid including the n points on the curved segment close to the starboard side on each vertical section w discrete points. Among them, the target width displacement value is set according to the line type modification requirements. This application sets the target width displacement value to -20% to +40% of the horizontal semi-axis length of the bottom surface of the deformation control domain, that is, the width of the to-be-deformed shroud is modified to be widened to 20% of the width W of the to-be-deformed shroud at most, and the width of the to-be-deformed shroud is modified to be narrowed to 10% of the width W of the to-be-deformed shroud at most. For example, if the width of the to-be-deformed shroud is modified to be 30mm wider, then the displacement value of all discrete points on the left surface of the semi-ellipsoid is the target width displacement value of -30mm, and the displacement value of all discrete points on the right surface of the semi-ellipsoid is +30mm. The setting of the deformation control domain is as follows: Figure 7 shown.

[0058] When the linear modification requirement indicates a change in the downward angle of the deformable shroud along the vertical semi-axis, a fixed constraint is applied to the bottom surface of the deformation control domain, and a displacement constraint is applied to the missing top surface of the deformation control domain. Since the lowest point of the deformable shroud along the z-direction and the lowest point of the surface ship along the z-direction both lie on the xz plane, the downward angle of the deformable shroud can be modified by adjusting the displacement values ​​of discrete points on the missing top surface along the z-direction. The displacement values ​​of all discrete points on the bottom surface of the deformation control domain in the x, y, and z directions are determined to be zero. The displacement values ​​of all discrete points on the missing top surface of the deformation control domain in the z-direction are determined to be the target downward angle displacement value, and the displacement values ​​in the x and y directions are determined to be zero. When the linear modification requirement indicates a smaller downward angle change, the target downward angle displacement value is negative; when the linear modification requirement indicates a larger downward angle change, the target downward angle displacement value is positive. The absolute value of the target downward angle displacement value is related to the change in the downward angle of the deformable shroud. Among them, the target downward angular displacement value is set according to the requirements of the line type modification. In this application, the target downward angular displacement value is set to -40% to +100% of the vertical semi-axis length of the bottom surface of the deformation control domain, that is, the modified top surface of the to-be-deformed guide cover is moved downward by a maximum of 20% of the height L of the to-be-deformed guide cover, and the modified top surface of the to-be-deformed guide cover is moved upward by a maximum of 50% of the height L of the to-be-deformed guide cover. For example, if the modified top surface of the to-be-deformed guide cover is moved downward by 30mm, the target downward angular displacement value is -30mm, and the setting of the deformation control domain is as follows: Figure 8 shown.

[0059] Step 4: Based on the linear modification requirement of minimizing the gradient of the displacement values ​​of all discrete points in the deformation control domain, the Laplace displacement equation is constructed. The Laplace displacement equation is solved using the displacement values ​​of the discrete points on the top, bottom, mid-longitudinal and side surfaces of the semi-ellipsoid of the deformation control domain to obtain the displacement values ​​of other discrete points in the deformation control domain.

[0060] This application introduces Laplace constraints to minimize the gradient of the displacement value of discrete points in the entire control domain, thereby ensuring that the deformed deflector surface is smoother than the traditional FFD method. The displacement value of each discrete point in the deformation control domain satisfies the Laplace equation. In one embodiment, the Laplace shift equation for any discrete point (i, j, k) is constructed as follows:

[0061]

[0062] Among them, the discrete point (i+1, j, k) is the adjacent discrete point of the discrete point (i, j, k) in the major semi-axis direction, the discrete point (i, j+1, k) is the adjacent discrete point of the discrete point (i, j, k) in the horizontal semi-axis direction, and the discrete point (i, j, k+1) is the adjacent discrete point of the discrete point (i, j, k) in the vertical semi-axis direction; h ix is the distance between discrete points (i, j, k) and discrete points (i+1, j, k) in the direction of the major semi-axis, h iy is the distance between discrete points (i, j, k) and discrete points (i+1, j, k) in the horizontal semi-axis direction, h iz is the distance between the discrete point (i, j, k) and the discrete point (i+1, j, k) in the vertical semi-axis direction; f ijk is the displacement value of the discrete point (i, j, k), f (i+1)jk is the displacement value of the discrete point (i+1,j,k), f (i+2)jk is the displacement value of the discrete point (i+2,j,k), f i(j+1)k is the displacement value of the discrete point (i, j+1, k), f i(j+2)k is the displacement value of the discrete point (i, j+2, k), f ij(k+1) is the displacement value of the discrete point (i, j, k+1), f ij(k+2) is the displacement value of the discrete point (i, j, k+2).

[0063] In order to solve the Laplace shift equation conveniently, the Laplace shift equation formula (1) is expressed in matrix form as follows:

[0064]

[0065] In the same way, the matrix form of the Laplace shift equation is listed for discrete points (i+1, j, k):

[0066]

[0067] Integrate formula (2) and formula (3) into a matrix equation:

[0068]

[0069] By analogy, the Laplace shift equations of all discrete points are integrated into one Laplace shift equation, and its corresponding matrix equation form is:

[0070] Mf=N (5)

[0071] Where M is the coefficient matrix, whose number of rows and columns are the total number of discrete points in the deformation control domain; f is the displacement vector to be solved, and the elements in the displacement vector f are the displacement values ​​of all discrete points; N is the right-hand vector, whose elements are all initialized to 0.

[0072] The displacement values ​​of the discrete points on the missing top, bottom, mid-longitudinal, and side surfaces of the semi-ellipsoid of the deformation control domain are then used to update the values ​​of the elements in the coefficient matrix M, the displacement vector f, and the right-hand vector N. For a discrete point (i, j, k), if the discrete point is located on the missing top, bottom, mid-longitudinal, or side surfaces of the deformation control domain, the displacement value of the point is known. Assuming that the displacement value of the discrete point is in the mth row of the displacement vector f, the element in the mth row and mth column of the coefficient matrix M is set to 1, the remaining elements in the mth row are set to 0, and the element in the mth row of the right-hand vector N is set to the corresponding displacement value. The displacement values ​​of all discrete points on the missing top, bottom, mid-longitudinal, and side surfaces of the deformation control domain are updated into the matrix equation. At this point, the only remaining unknowns in the matrix equation are the displacement values ​​of the other discrete points in the deformation control domain. Therefore, the Laplace displacement equation is solved to obtain the displacement values ​​of the other discrete points in the deformation control domain.

[0073] Step 5: Using NURBS function and interpolation algorithm, the displacement value of any surface control point of the to-be-deformed shroud is interpolated according to the displacement value of each discrete point in the deformation control domain.

[0074] In one embodiment, the specific steps of determining the displacement value of any surface control point of the to-be-deformed shroud are as follows:

[0075] (1) Using NURBS function and interpolation algorithm to construct the interpolation coefficient linear equation system containing unknown interpolation coefficients is:

[0076]

[0077] Among them, S(u,v,w) is the displacement value of any position coordinate (u,v,w) in the global coordinate system, N i,p (u) is the i-th p-order B-spline basis function, N j,q (v) is the j-th q-order B-spline basis function, N k,r (w) is the kth r-order B-spline basis function, Represents the tensor product, and the expression of the B-spline basis function is:

[0078]

[0079] Among them, N i,p (u), N j,q (v) N k,r (w) can be calculated by formula (7). The orders p, q, and k of the B-spline basis function can be set according to the accuracy requirements of the line type modification. The higher the order, the higher the accuracy, but the greater the amount of calculation. In order to improve the calculation efficiency while ensuring the accuracy, the order is generally set to 2.

[0080] (2) The interpolation coefficient U in the linear equations of the interpolation coefficients is obtained by solving the position coordinates and displacement values ​​of all discrete points in the deformation control domain in the global coordinate system. ijk .

[0081] In one embodiment, the position coordinates of all discrete points in the global coordinate system are normalized along the x, y, and z directions to obtain dimensionless position coordinates. The normalized position coordinates represent the relative positions of the discrete points along the corresponding directions in the deformation control domain. The position coordinates (x, y, and z) of any discrete point (i, j, k) in the global coordinate system are i ,y j ,z k ) is converted to the corresponding normalized position coordinates (u i ,v j ,w k )and Among them, x max is the maximum value of the x coordinate of all discrete points in the deformation control domain, x min is the minimum value of the x coordinate of all discrete points in the deformation control domain, and y max is the maximum value of the y coordinate of all discrete points in the deformation control domain, y min is the minimum value of the y coordinate of all discrete points in the deformation control domain, z max is the maximum value of the z coordinate of all discrete points in the deformation control domain, z min is the minimum value of the z coordinate of all discrete points in the deformation control domain.

[0082] The normalized position coordinates (u i ,v j ,w k ) and displacement value f ijk Substitute into the equation Solve the interpolation coefficient U in the linear equation system ijk , f ijk is the displacement value of the discrete point (i, j, k).

[0083] (3) Using the interpolation coefficient linear equation group, the displacement value of the current surface control point is determined according to the position coordinates of any surface control point of the deflector to be deformed in the global coordinate system.

[0084] For any surface control point Pc, its position coordinates Pc(x,y,z) in the global coordinate system are converted to normalized position coordinates (u(p c ),v(p c ),w(p c )), and then substitute into formula (6) to obtain the displacement value S(u(p c ),v(p c),w(p c ))=(ΔP cu ,ΔP cv ,ΔP cw ), the interpolation coefficient U in formula (6) ijk It has been calculated in (2).

[0085] Step 6: Modify the line type of the deformed air duct according to the displacement value of each surface control point to obtain a modified line type that meets the line type modification requirements.

[0086] For any surface control point Pc, the position coordinates (x+ΔP cu ,y+ΔP cv ,z+ΔP cw ). Substituting the position coordinates of all surface control points on the deflector to be deformed into the NURBS curve equation, the modified line shape can be obtained. The specific form of the NURBS curve equation can be referred to the content of the prior art and will not be repeated in this application.

[0087] According to the target length displacement value in step 3, the length of the deformed guide cover is modified linearly to deform the guide cover. The comparison results between the deformed guide cover and the original guide cover are as follows: Figure 9 As shown, the length of the deformed guide cover is longer than that of the original guide cover to be deformed. According to the target width displacement value in step 3, the width of the deformed guide cover is linearly modified to deform the guide cover to be deformed. The comparison results between the deformed guide cover and the original guide cover to be deformed are shown as follows: Figure 10 As shown in the figure, the width of the deformed guide cover is wider than that of the original guide cover to be deformed. According to the target downward angle displacement value in step 3, the downward angle of the deformed guide cover is linearly modified to deform the guide cover to be deformed. The comparison results between the deformed guide cover and the original guide cover to be deformed are shown in the figure. Figure 11 As shown, the downward angle of the deformed air guide cover becomes larger than that of the original air guide cover to be deformed.

[0088] The above description is only a preferred embodiment of the present application, and the present application is not limited to the above embodiments. It is understood that other improvements and variations directly derived or imagined by those skilled in the art without departing from the spirit and concept of the present application should be considered to be included in the scope of protection of the present application.

Claims

1. A method for modifying the line shape of a surface ship deflector, characterized in that: The line type modification method includes: A deformation control domain is established according to the to-be-deformed fairing, wherein the deformation control domain is a semi-ellipsoid with a missing top and encloses the to-be-deformed fairing, and the long semi-axis of the deformation control domain is along the ship length, the horizontal semi-axis is along the ship width, and the vertical semi-axis is along the ship height; Uniformly discretizing the deformation control domain to obtain a plurality of discrete points; Determine the displacement values ​​of discrete points on the missing top surface, bottom surface, mid-longitudinal surface, and side surface of the semi-ellipsoid of the deformation control domain according to the line type modification requirements; the bottom surface of the deformation control domain is the plane where the horizontal semi-axis and the vertical semi-axis are located and is perpendicular to the major semi-axis direction; the missing top surface of the deformation control domain is parallel to the bottom surface of the deformation control domain; the mid-longitudinal surface of the deformation control domain is the plane where the major semi-axis and the vertical semi-axis are located and is perpendicular to the horizontal semi-axis; A Laplace displacement equation is constructed based on the linear modification requirement of minimizing the gradient of the displacement values ​​of all discrete points in the deformation control domain, and the Laplace displacement equation is solved using the displacement values ​​of the discrete points on the missing top surface, bottom surface, mid-longitudinal surface, and side surface of the semi-ellipsoid of the deformation control domain to obtain the displacement values ​​of other discrete points in the deformation control domain; The NURBS function and interpolation algorithm are used to interpolate the displacement value of any surface control point of the to-be-deformed air deflector according to the displacement value of each discrete point in the deformation control domain, and the linear shape of the to-be-deformed air deflector is modified according to the displacement value of each surface control point to obtain a modified linear shape that meets the linear shape modification requirements.

2. The line type modification method according to claim 1, characterized in that: The deformation control domain is uniformly discretized to obtain a plurality of discrete points including: The deformation control domain is uniformly discretized along the long semi-axis direction to obtain n u vertical sections; for each vertical section: uniformly divide the vertical section along the horizontal semi-axis direction to obtain n sections containing the vertical semi-axis. v -2 mutually parallel transverse segments and two curve segments on both sides, each transverse segment and each curve segment are uniformly discretized along the vertical semi-axis direction to obtain n discrete points including those located on the straight line where the horizontal semi-axis is located w discrete points; Each vertical section is discretized to obtain n v ×n w discrete points, the deformation control domain is discretized to obtain n u ×n v ×n w The position coordinates of the kth discrete point (i, j, k) from bottom to top on the jth sectional segment starting from the port side on the i-th vertical section starting from the missing top surface in the global coordinate system are marked as (x i ,y j ,z k ); the global coordinate system takes the intersection of the vertical line passing through the front end point of the bow and the bottom surface of the hull as its origin, the positive direction of the x-axis points to the stern, the positive direction of the y-axis points to the starboard side, and the positive direction of the z-axis is vertically upward; the long semi-axis direction of the deformation control domain is along the x-axis direction of the global coordinate system, the horizontal semi-axis direction is along the y-axis direction, and the vertical semi-axis direction is along the z-axis direction.

3. The line type modification method according to claim 2, characterized in that: Determining the displacement values ​​of discrete points on the missing top surface, bottom surface, mid-longitudinal surface and side surface of the semi-ellipsoid of the deformation control domain according to the line type modification requirements includes: When the line type modification requirement indicates that the length of the deflector to be deformed along the semi-major axis is modified, the displacement values ​​of all discrete points on the bottom surface of the deformation control domain in the x-, y-, and z-directions are determined to be 0, and the displacement value of all discrete points on the top surface of the deformation control domain in the x-direction is determined to be the target length displacement value, and the displacement values ​​in the y- and z-directions are determined to be 0; when the line type modification requirement indicates that the deflector to be deformed is modified to be longer, the target length displacement value is negative; when the line type modification requirement indicates that the deflector to be deformed is modified to be shorter, the target length displacement value is positive; the absolute value of the target length displacement value is related to the length change of the deflector to be deformed; When the line type modification requirement indicates that the width of the deformable shroud to be modified along the horizontal semi-axis direction is modified, the displacement values ​​of all discrete points on the mid-longitudinal surface of the deformation control domain in the x-direction, y-direction and z-direction are determined to be 0, and the displacement value of all discrete points on the left side surface of the semi-ellipsoid of the deformation control domain in the y-direction is determined to be the target width displacement value, and the displacement values ​​in the x-direction and z-direction are determined to be 0; the displacement values ​​of all discrete points on the right side surface of the semi-ellipsoid of the deformation control domain in the y-direction are determined to be equal in magnitude and opposite in direction to the displacement values ​​of all discrete points on the left side surface of the semi-ellipsoid, and the displacement values ​​in the x-direction and z-direction are determined to be 0; when the line type modification requirement indicates that the deformable shroud to be modified to be wider, the target width displacement value is negative; when the line type modification requirement indicates that the deformable shroud to be modified to be narrower, the target width displacement value is positive; the absolute value of the target width displacement value is related to the width change of the deformable shroud to be deformed; wherein, all discrete points on the left side surface of the semi-ellipsoid include n on the curved segment close to the port side on each vertical section w discrete points; all discrete points on the right side of the semi-ellipsoid including the n points on the curved segment close to the starboard side on each vertical section w discrete points; When the linear modification requirement indicates that the downward angle of the deformed shroud to be deformed along the vertical semi-axis direction is modified, the displacement values ​​of all discrete points on the bottom surface of the deformation control domain in the x-direction, y-direction, and z-direction are determined to be 0, and the displacement value of all discrete points on the top surface of the deformation control domain in the z-direction is determined to be the target downward angle displacement value, and the displacement values ​​in the x-direction and y-direction are 0; when the linear modification requirement indicates that the downward angle of the deformed shroud to be deformed is modified to become smaller, the target downward angle displacement value is negative; when the linear modification requirement indicates that the downward angle of the deformed shroud to be deformed is modified to become larger, the target downward angle displacement value is positive; the absolute value of the target downward angle displacement value is related to the change in the downward angle of the deformed shroud to be deformed; the downward angle represents the angle between the line connecting the lowest point of the deformed shroud to be deformed along the z-direction and the lowest point of the surface ship along the z-direction and the x-axis.

4. The line type modification method according to claim 2, characterized in that: Constructing the Laplace shift equation includes constructing the Laplace shift equation for any discrete point (i, j, k) as: Among them, the discrete point (i+1, j, k) is the adjacent discrete point of the discrete point (i, j, k) in the major semi-axis direction, the discrete point (i, j+1, k) is the adjacent discrete point of the discrete point (i, j, k) in the horizontal semi-axis direction, and the discrete point (i, j, k+1) is the adjacent discrete point of the discrete point (i, j, k) in the vertical semi-axis direction; h ix is the distance between discrete points (i, j, k) and discrete points (i+1, j, k) in the direction of the major semi-axis, h iy is the distance between discrete points (i, j, k) and discrete points (i+1, j, k) in the horizontal semi-axis direction, h iz is the distance between the discrete point (i, j, k) and the discrete point (i+1, j, k) in the vertical semi-axis direction; f ijk is the displacement value of the discrete point (i, j, k), f (i+1)jk is the displacement value of the discrete point (i+1,j,k), f (i+2)jk is the displacement value of the discrete point (i+2,j,k), f i(j+1)k is the displacement value of the discrete point (i, j+1, k), f i(j+2)k is the displacement value of the discrete point (i, j+2, k), f ij(k+1) is the displacement value of the discrete point (i, j, k+1), f ij(k+2) is the displacement value of the discrete point (i, j, k+2).

5. The line type modification method according to claim 3, characterized in that: The target length displacement value is -20% to +50% of the distance between the top surface and the bottom surface of the deformation control domain along the x-direction; the target width displacement value is -20% to +40% of the horizontal semi-axis length of the bottom surface of the deformation control domain; and the target downward angle displacement value is -40% to +100% of the vertical semi-axis length of the bottom surface of the deformation control domain.

6. The line type modification method according to claim 2, characterized in that: Determining the displacement value of any surface control point of the to-be-deformed fairing includes: Using NURBS functions and interpolation algorithms to construct a linear equation system of interpolation coefficients including unknown interpolation coefficients; The interpolation coefficient U in the linear equation group of interpolation coefficients is obtained by solving the position coordinates and displacement values ​​of all discrete points in the deformation control domain in the global coordinate system. ijk ; The interpolation coefficient linear equation group is used to determine the displacement value of the current surface control point according to the position coordinates of any surface control point of the to-be-deformed fairing in the global coordinate system.

7. The line type modification method according to claim 6, characterized in that: The interpolation coefficient linear equations are: Among them, S(u,v,w) is the displacement value of any position coordinate (u,v,w) in the global coordinate system, N i,p (u) is the i-th p-order B-spline basis function, N j,q (v) is the j-th q-order B-spline basis function, N k,r (w) is the kth r-order B-spline basis function, Represents the tensor product, and the expression of the B-spline basis function is:

8. The line type modification method according to claim 7, characterized in that: The interpolation coefficient U in the linear equation group of interpolation coefficients is obtained by solving the position coordinates and displacement values ​​of all discrete points in the deformation control domain in the global coordinate system. ijk include: The position coordinates (x i ,y j ,z k ) is converted to the corresponding normalized position coordinates (u i ,v j ,w k )and Among them, x max is the maximum value of the x coordinate of all discrete points in the deformation control domain, x min is the minimum value of the x coordinate of all discrete points in the deformation control domain, and y max is the maximum value of the y coordinate of all discrete points in the deformation control domain, y min is the minimum value of the y coordinate of all discrete points in the deformation control domain, z max is the maximum value of the z coordinate of all discrete points in the deformation control domain, z min is the minimum value of the z coordinate of all discrete points in the deformation control domain; according to Solve the interpolation coefficient U in the linear equation system ijk , f ijk is the displacement value of the discrete point (i, j, k).

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