Parametric design method of integrated energy-saving propulsion system for ship

Abstract

The application relates to a parameterized design method of a ship integrated energy-saving propulsion system. The method comprises the following steps: dividing the ship integrated energy-saving propulsion system into several structural bodies, and designing a parameter set for the ship integrated energy-saving propulsion system and the structural bodies; when the posterior constraint characteristic quantity does not match the posterior constraint target characteristic quantity, adjusting the geometric design parameter subset, and repeating the posterior constraint characteristic quantity solving after the geometric design parameter subset is adjusted until the posterior constraint characteristic quantity matches the posterior constraint target characteristic quantity; and generating an entity ship integrated energy-saving propulsion system based on the geometric model of the structural bodies and performing a multi-body Boolean operation. The application can realize parameterized modeling and modification design of a hydrodynamic configuration with fewer parameters.

Description

Technical Field

[0001] This invention relates to a parametric design method, and more particularly to a parametric design method for an integrated energy-saving propulsion system for ships. Background Technology

[0002] With the trend towards larger ships, the International Maritime Organization's requirements for energy conservation and environmental protection, as well as shipowners' energy-saving needs, are gradually increasing. Therefore, higher demands are being placed on the innovative and optimized design of hull lines and propulsion systems. Optimizing hull lines, developing hydrodynamic energy-saving devices, and optimizing the design of high-efficiency propeller-rudder systems are currently the main technical means to achieve green and energy-saving ships.

[0003] With the further development of computer hardware and numerical methods, hydrodynamic performance analysis and auxiliary optimization design based on CFD (Computational Fluid Dynamics) numerical simulation has become a routine method for the comprehensive performance optimization design of ships. When designing based on CFD, the influence of hull optimization, energy-saving device development and propeller and rudder design results on detailed flow fields and macroscopic hydrodynamic performance can be effectively considered, thereby obtaining excellent design solutions and significantly reducing the experimental costs in the optimization design process.

[0004] Parametric design technology can accurately and efficiently represent the shape of transformed entities and achieve rapid response to design parameters, playing a crucial role in ship hull optimization. After years of engineering applications and theoretical research, hydrodynamic configuration design technology based on parametric / semi-parametric methods has been widely applied in the optimization design of ship hull forms, hydrodynamic energy-saving devices, and propellers.

[0005] Currently, the mainstream process for optimizing ship performance involves treating the hull, propeller, energy-saving devices, and rudder as relatively independent geometric components. Different designers at different design stages optimize the hydrodynamic shape of these components, parametrically modeling the airfoils of the propeller and rudder, and incorporating expert experience. This approach fails to effectively consider the interactions between various combinations of the hull, propeller, rudder, and energy-saving devices, neglecting the integrated effect of the ship as a system and thus failing to meet practical parametric design requirements. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a parametric design method for an integrated energy-saving propulsion system for ships. This method can achieve parametric modeling and modification design of hydrodynamic configuration with fewer parameters, and can also reflect the parameter correlation and constraint relationships between various combinations.

[0007] According to the technical solution provided by the present invention, a parametric design method for an integrated energy-saving propulsion system for ships is provided, the parametric design method comprising:

[0008] For a parametrically designed integrated energy-saving propulsion system for a ship, determine the reference coordinate system of the integrated energy-saving propulsion system for the ship;

[0009] The above-mentioned integrated energy-saving propulsion system for ships is structurally divided into several structural components, wherein the divided structural components include at least the hull, hydrodynamic energy-saving device, propeller and high-efficiency rudder.

[0010] For the aforementioned integrated energy-saving propulsion system for ships and the divided structural bodies, a parameter set is designed. The designed parameter set includes a subset of geometric design parameters corresponding to each structural body and a subset of associated constraint problem parameters used to characterize the associated constraint conditions. The subset of associated constraint problem parameters includes a set of prior constraint problems corresponding to each structural body and a set of posterior constraint problems corresponding to the integrated energy-saving propulsion system for ships.

[0011] For any construct, a parametric geometric model of the construct is generated. When generating the parametric geometric model, the parametric geometric model of the construct is constructed sequentially based on the corresponding subset of geometric design parameters and the set of prior constraint problems.

[0012] After constructing the parametric geometric model of all the constructs, the posterior constraint characteristic quantities of the integrated energy-saving propulsion system of the ship are solved based on the set of posterior constraint problems.

[0013] When the posterior constraint feature quantity does not match the posterior constraint target feature quantity, the above-mentioned geometric design parameter subset is adjusted, and the above-mentioned posterior constraint feature quantity solution is repeated after adjusting the above-mentioned geometric design parameter subset until the posterior constraint feature quantity matches the posterior constraint target feature quantity.

[0014] Based on the geometric model of the above-mentioned construct, a physical integrated energy-saving propulsion system for the ship is generated, and multi-body Boolean operations are performed to generate the target integrated energy-saving propulsion system for the ship after the multi-body Boolean operations.

[0015] When the structure is a ship hull, the subset of geometric design parameters for the hull includes a subset of global structural parameters and a subset of local deformation parameters. The method for generating the parametric geometric model of the hull includes:

[0016] The main outline of the hull is generated based on a subset of global hull construction parameters.

[0017] NUBRS surface control points of the hull are generated based on a subset of local deformation parameters of the hull.

[0018] Associate the NUBRS surface control points of the hull with the main contour of the hull, and generate the hull surface after association.

[0019] The NUBRS surface of the hull is generated based on the above-mentioned hull surface.

[0020] When the generated NUBRS surface satisfies the set of prior constraints of the hull, the NUBRS surface is configured as the parametric geometric model of the hull.

[0021] The global construction parameter subset includes a principal dimension parameter set and a hull feature line parameter set defined based on NURBS curves. When generating the main contour of the hull based on the global construction parameter subset, the process includes:

[0022] Construction control points for curves based on the set of principal scale parameters and the set of hull feature line parameters;

[0023] Deformation control points are obtained based on the construction control points of the curve and the NURBS curve order constraints.

[0024] A set of control points is generated based on the construction control points and deformation control points, and a NURBS feature curve is generated. In the generated NURBS feature curve, the straight line segments are directly generated by the construction control points, and the straight line segments and curve segments are spliced ​​together to form the main outline of the hull.

[0025] The subset of local deformation parameters for the hull includes a subset of reduced-order NURBS parameters for the hull and a subset of hull region parameters, wherein...

[0026] Adjustment control points are generated based on the hull-downgraded NURBS parameter subset and the hull region parameter subset.

[0027] A radial basis interpolation function is used to generate new NURBS surface control points based on the adjusted control points. Based on the new NURBS surface control points, the NURBS expression of the modified ship shape surface is obtained through NURBS surface calculation to generate the hull surface.

[0028] When the structure is a hydrodynamic energy-saving device, a propeller, or a high-efficiency rudder, the parametric geometric model of the structure is constructed using a fully parametric method based on airfoil profiles.

[0029] When constructing an airfoil using a fully parametric approach based on its airfoil profile, the geometric representation of the airfoil profile is controlled by the shape of the arch and the thickness distribution.

[0030] The set of prior constraint problems includes:

[0031] The stator blades of the hydrodynamic energy-saving device are subject to distance constraints from the lowest point of the hull to the lower edge of the ship in the reference coordinate system: l HD<L HD L HD For the specified constraint parameters;

[0032] The distance x between the reference surface of the hydrodynamic energy-saving device and the stern shaft outlet plane D >0;

[0033] Propeller blade tip distance from the reference plane to the lower edge of the hull is constrained as follows: l HP <L HP , where L HP For the specified constraint parameters;

[0034] The rudder blades do not intersect with the propeller.

[0035] The advantages of this invention are: the integrated energy-saving propulsion system of a ship is divided into structural bodies, the parameter set of the structural bodies is designed, and the structural bodies are parametrically modeled and modified using a subset of geometric design parameters and a subset of parameters related to constraint problems. In other words, the parametric modeling and modification design of hydrodynamic configurations can be achieved with fewer parameters, while also reflecting the parameter relationships and constraint relationships between various combinations. Attached Figure Description

[0036] Figure 1 This is a flowchart illustrating one embodiment of the parametric design of the present invention.

[0037] Figure 2 This is a schematic diagram of one embodiment of the integrated energy-saving recommendation system for ships of the present invention.

[0038] Figure 3 This is a flowchart illustrating the generation process of a parametric geometric model of the hull of the present invention. Detailed Implementation

[0039] The present invention will be further described below with reference to specific accompanying drawings and embodiments.

[0040] To enable parametric modeling and modification design of hydrodynamic configurations with fewer parameters, in one embodiment of the present invention, a parametric design method for integrated energy-saving propulsion systems of ships includes:

[0041] For a parametrically designed integrated energy-saving propulsion system for a ship, determine the reference coordinate system of the integrated energy-saving propulsion system for the ship;

[0042] The above-mentioned integrated energy-saving propulsion system for ships is structurally divided into several structural components, wherein the divided structural components include at least the hull, hydrodynamic energy-saving device, propeller and high-efficiency rudder.

[0043] For the aforementioned integrated energy-saving propulsion system for ships and the divided structural bodies, a parameter set is designed. The designed parameter set includes a subset of geometric design parameters corresponding to each structural body and a subset of associated constraint problem parameters used to characterize the associated constraint conditions. The subset of associated constraint problem parameters includes a set of prior constraint problems corresponding to each structural body and a set of posterior constraint problems corresponding to the integrated energy-saving propulsion system for ships.

[0044] For any construct, a parametric geometric model of the construct is generated. When generating the parametric geometric model, the parametric geometric model of the construct is constructed sequentially based on the corresponding subset of geometric design parameters and the set of prior constraint problems.

[0045] After constructing the parametric geometric model of all the constructs, the posterior constraint characteristic quantities of the integrated energy-saving propulsion system of the ship are solved based on the set of posterior constraint problems.

[0046] When the posterior constraint feature quantity does not match the posterior constraint target feature quantity of the design input, the above-mentioned geometric design parameter subset is adjusted, and the above-mentioned posterior constraint feature quantity solution is repeated after adjusting the above-mentioned geometric design parameter subset until the posterior constraint feature quantity matches the posterior constraint target feature quantity.

[0047] Based on the geometric model of the above-mentioned construct, a physical integrated energy-saving propulsion system for the ship is generated, and multi-body Boolean operations are performed to generate the target integrated energy-saving propulsion system for the ship after the multi-body Boolean operations.

[0048] For integrated energy-saving propulsion systems for ships, Figure 1 The figure illustrates an embodiment of the parametric design method for the integrated energy-saving propulsion system of a ship. In the figure, a reference coordinate system needs to be determined first during parametric design. Specifically, when parametrically designing an integrated energy-saving propulsion system for a ship, the design starting point is generally the shape of a similar reference ship. After defining the reference coordinate system, multiple geometric components can be conveniently placed within the same coordinate system to complete the assembly and unified expression of the spatial positional relationships of each component.

[0049] In one embodiment of the present invention, the required parent ship is selected based on a database, which is a database of parent ships containing a large number of parent ships. The appropriate parent ship can be selected according to the specific situation of the integrated propulsion system of the ship. The specific method and process for selecting the parent ship can be consistent with the existing methods.

[0050] The aforementioned integrated energy-saving propulsion system for ships is structurally divided into several structural components. As shown in Figure 2, one embodiment of this division is illustrated. In the figure, each structural component includes a hull, a hydrodynamic energy-saving device, a propeller, and a high-efficiency rudder. Figure 2 The structural components are divided into several parts. The hull includes the main body, bulbous bow, stern bulb, and stern seal plate. The hydrodynamic energy-saving device consists of a guide wheel and a stator, or it can consist of a separate guide wheel or a separate stator. The propeller includes blades, a hub, and a hub cap. The high-efficiency rudder includes a rudder body, a fixed rudder, and a rudder bulb, including unconventional rudder types such as a twisted rudder. In specific implementation, the corresponding components of the hull, hydrodynamic energy-saving device, propeller, and high-efficiency rudder can be selected according to needs, based on the objective of parametric design.

[0051] In practical implementation, the determined reference coordinate system is configured as the ship type coordinate system of the integrated energy-saving propulsion system. Then, we have:

[0052] Define the reference coordinate system and the ship type coordinate system Oxyz: the positive direction of the Ox axis points to the bow, the positive direction of the Oy axis points to the port side, the flat bottom surface of the ship type is the xOy plane, the mid-longitudinal section is the xOz plane, the origin of the coordinate system O is located at the intersection of the stern vertical line and the xOy plane, the direction from the bottom of the ship to the deck is the positive direction of the z axis, and the coordinate system is a right-handed coordinate system;

[0053] Define an efficient rudder coordinate system: The rudder coordinate system is consistent with the reference coordinate system, its z-axis coincides with the stern vertical line and the rudder stock, and the spatial position coordinates of the rudder bottom plane in the reference coordinate system are defined as (0, y). R ,z R ), that is, the distance y from the longitudinal section line in the ship's shape. R Distance z from the bottom baseline of the ship R Sure.

[0054] Define the propeller coordinate system: The propeller coordinate system is a cylindrical coordinate system (x, r, θ), with the x-axis being the stern axis. The direction from propeller forward to propeller backward is positive, and the propeller disk surface is the rOθ plane. The origin is the intersection of the propeller disk surface and the axis. The spatial position coordinates of the center point of the propeller disk surface in the reference coordinate system are defined as (x...r...θ). P ,y P ,z P The distance is determined by the distance from the stern vertical line, the mid-longitudinal section line, and the bottom baseline of the ship.

[0055] Define the coordinate system of the hydrodynamic energy-saving device: The coordinate system of the energy-saving device is also a cylindrical coordinate system (x, r, θ), with the x-axis being the stern axis. The positive x-axis direction is from the duct follower edge to the guide edge, and the plane containing the follower edge is the rOθ plane (reference plane). The spatial position of the reference plane in the reference coordinate system is determined by its distance x from the stern perpendicular of the hull. DSure.

[0056] After determining the coordinate system positional relationship of each independent component, the positional relationship of the hull, propeller, rudder and hydrodynamic energy-saving device is determined through coordinate system transformation. Among them, the hydrodynamic energy-saving device may undergo further geometric transformations such as translation along the reference coordinate system z and rotation around the origin of the hydrodynamic energy-saving device coordinate system.

[0057] The parameter set for the design includes a subset of geometric design parameters and a subset of parameters related to the constraint problem. The subset of geometric design parameters within the parameter set corresponds one-to-one with the partitioned construct. That is, the subset of geometric design parameters will be different when the type of construct is different. The specific situation of the subset of geometric design parameters for the specific type of construct will be explained in detail below.

[0058] The parameter subset of the associated constraint problem specifically includes the set of prior constraint problems and the set of posterior constraint problems. Among them, the prior constraints generally refer to the geometric constraints input by the general layout design, such as the ship's deadweight, main dimensions, compartment division, placement space of the ship's main equipment (main engine / generator, etc.), and deck layout. During the geometric design parameterization process, the constraints can directly avoid exceeding the given limit points or limit distances under the corresponding hydrodynamic geometry of the hull, propeller, high-efficiency rudder, and hydrodynamic energy-saving devices and their matching positional relationships.

[0059] In practical implementation, during parametric modeling / redesign, the geometry of the construct is directly controlled through prior constraints, such as the input of main dimensional constraint parameters and constraint parameters like the coordinates of limit points on a cross section / longitudinal section / waterline. Prior constraints can be consistent with existing ones and can be configured using techniques commonly used in this field. Generally, prior constraints may include:

[0060] The width constraint at the line restriction point near the engine room of the ship must not be less than a given value;

[0061] The constraints on the matching relationship between the propeller and rudder positions of the high-efficiency rudder require that the disassembly distance between the propeller disk surface, the stern shaft outlet end face of the hull, and the geometric leading edge of the high-efficiency rudder must meet the requirements.

[0062] The diameter of the guide tube of the energy-saving guide wheel in the hydrodynamic energy-saving device is smaller than that of the propeller.

[0063] Posterior constraints generally refer to constraints that can only be obtained by calculating the integrated geometric components after the geometric model of the structure is completed, thereby determining whether they meet the limiting conditions. In practice, commonly used techniques in this technical field can be employed to calculate these posterior constraint features. Posterior constraints can be consistent with existing methods and can be configured using commonly used techniques in this technical field. Generally, posterior constraints may include constraints such as the ship's displacement volume and center of buoyancy, as well as constraint parameters such as results calculated after a given ship type. Posterior constraints may include:

[0064] The ship's displacement volume must be no less than the target value;

[0065] The propeller-propeller matching relationship is constrained, and the gap between the propeller blade tip and the hull surface is not less than a given empirical value, so as to avoid its influence on the induced excitation force of the hull.

[0066] The rudder-ship matching relationship of the high-efficiency rudder is constrained, and the height of the stern profile of the hull must meet a given limit value to ensure sufficient rudder area.

[0067] Figure 1 In this process, after obtaining the parametric geometric models of all structures, and combining them with the set of posterior constraint problems, the posterior constraint characteristic quantities can be solved using techniques commonly used in this technical field. The posterior constraint target characteristic quantities are generally design inputs, such as characteristic parameter values ​​like the displacement volume and center of buoyancy of a certain sub-draft hull type. The posterior constraint target characteristic quantities are a subset of the posterior problem set. After obtaining the posterior constraint characteristic quantities, they can be compared and judged using techniques commonly used in this technical field.

[0068] In practice, the subset of geometric design parameters and the subset of parameters related to constraint problems in the parameter set are given externally, such as according to the actual working scenario of the integrated energy-saving propulsion system of the ship, or given under other circumstances.

[0069] After constructing the parameter set, the parametric geometric model of each structure can be determined. Generally, when generating the parametric geometric model, it is necessary to construct the parametric geometric model of the structure based on the corresponding subset of geometric design parameters and the set of prior constraint problems. The basic shape of the structure can be obtained through the constructed parametric geometric model. The following section provides a detailed explanation of the specific methods and processes for generating the parametric geometric model for the cases where the structures are a hull, a hydrodynamic energy-saving device, a propeller, and a high-efficiency rudder.

[0070] In one embodiment of the present invention, when the structure is a ship hull, the subset of geometric design parameters for the ship hull includes a subset of global structural parameters and a subset of local deformation parameters. The method for generating the parametric geometric model of the ship hull includes:

[0071] The main outline of the hull is generated based on a subset of global hull construction parameters.

[0072] NUBRS surface control points of the hull are generated based on a subset of local deformation parameters of the hull.

[0073] Associate the NUBRS surface control points of the hull with the main contour of the hull, and generate the hull surface after association.

[0074] The NUBRS surface of the hull is generated based on the above-mentioned hull surface.

[0075] When the generated NUBRS surface satisfies the set of prior constraints of the hull, the NUBRS surface is configured as the parametric geometric model of the hull.

[0076] The hydrodynamic shape of a ship's hull is typically a complex two-way curvature surface, and its parametric geometric model generally cannot be directly expressed using elementary analytical functions. Therefore, in one embodiment of the present invention, non-uniform rational B-splines (NURBS) parametric spline curves are introduced. Figure 3 The diagram illustrates an embodiment of constructing a parametric geometric model of a ship hull. Due to the complexity and special characteristics of the hull surface, it is difficult to construct a complete parametric geometric model. Therefore, in one embodiment of the present invention, when constructing the parametric geometric model of the hull, the idea of ​​integrating parametric design and variable design is adopted, and the geometric design parameters of the hull are divided into a global construction parameter subset and a hull feature line parameter set.

[0077] In practice, the main contour of the hull can be constructed based on a subset of global construction parameters. Based on the hull feature line parameter set, the hull surface is expressed using NURBS surface, and the control points are adjusted by combining reduced-order NURBS parameters and design parameters. The final NURBS surface control points are solved by solving simultaneous equations based on the parameters of the main hull contour and the deformation parameters of the control points, and the design surface is generated.

[0078] After generating the design surface, it is determined whether the high-order feature parameters of the hull entity generated by the surface and plane satisfy the prior constraints of the hull. If the prior constraints of the hull are satisfied, the surface details are checked and post-processed and the geometric file is exported. If not satisfied, the user is informed to adjust the subset of geometric design parameters of the hull.

[0079] In one embodiment of the present invention, the global construction parameter subset includes a principal dimension parameter set and a hull feature line parameter set defined based on NURBS curves, wherein generating the main contour of the hull based on the global construction parameter subset includes:

[0080] Construction control points for curves based on the set of principal scale parameters and the set of hull feature line parameters;

[0081] Deformation control points are obtained based on the construction control points of the curve and the NURBS curve order constraints.

[0082] A set of control points is generated based on the construction control points and deformation control points, and a NURBS feature curve is generated. In the generated NURBS feature curve, the straight line segments are directly generated by the construction control points, and the straight line segments and curve segments are spliced ​​together to form the main outline of the hull.

[0083] Specifically, the set of principal dimensional parameters of a ship's hull typically includes the length between perpendiculars (L... PP The main dimensional parameters representing the length, width, and height of a ship include the molded breadth (B) and molded depth (D). The hull feature line parameter set is defined by using NURBS curves to characterize the main feature lines and their structural parameters that characterize the hull profile. The feature lines of the hull profile may include the mid-longitudinal profile line, the flat bottom line, the flat edge line, the deck edge line, the stern plate edge line, and the stern shaft outlet profile line.

[0084] The feature line set of a ship's hull includes several feature lines. For each feature line of the hull, there may generally be hull characteristic value parameters, which may include the start point, end point, inflection point, and / or intersection point on the feature line. The case of hull characteristic value overparameters corresponds to the feature line.

[0085] As explained above, the characteristic value parameters of the hull feature lines encompass the characteristic point cloud value parameters that constitute the basic frame lines and characteristic transverse sections of the hull. These parameters include the longitudinal coordinates of the fore / aft of the parallel midbody (x_FRf / x_FRa), the bilge radius of the parallel midbody (Rbg), the longitudinal coordinates of the start and end points of the horizontal edge line (x_FBf and x_FBa), the longitudinal coordinates of the start and end points of the horizontal bottom line (x_FSf and x_FSa), the X and Z coordinates of the lowest point of the stern plate (x_Trans and z_minTrans), the Y coordinate of the widest point of the stern plate (y_maxTrans), and the stern... The coordinate parameters of basic feature points include the X and Z coordinates of the front curve point (x_SternFore, z_SternFore), the diameter of the stern shaft exit and the X and Z coordinates of the centerline point (D_shaft, x_Shaft, z_Shaft), the bow profile elevation (z_FpRise), the bulbous bow width (y_Bulb), the bulbous bow height (z_Bulb), the height of the intersection of the bulbous bow and the bowpost (z_FpBulb), and the X and Z coordinates of the foremost point of the bulbous bow (x_BulbTip and z_BulbTip), as well as the point cloud coordinates representing the shape of the feature cross section.

[0086] The master dimension parameter set and the hull feature line parameter set can constitute the main outline shape of the hull. Based on this, further addition of planes and curved surfaces can complete the modeling of the entire hull surface. The specific steps are as follows:

[0087] Based on the hull feature line parameter set, and taking the shape value points of the feature lines as the design starting point, the NURBS curve expression method is used to refit the shape value point cloud to obtain a standardized dimensionality-reduced NURBS expression. The specific operation is as follows: the order p of the NURBS curve is a positive integer, generally p≤3. It is assumed that the weight factor corresponding to each control point of the NURBS curve is 1.0. The parameterized expression of the feature lines is calculated based on the shape value points on each cross section; where n+1 shape value points {Q i} Parameterization is performed using the cumulative chord length method to calculate the control point {P} of the i-th characteristic line. i}, thus obtaining the NURBS parameterized expression for the cross section; here, the value of n and the specific process of obtaining the NURBS parameterized expression are consistent with the existing ones.

[0088] To more uniformly describe the curvature variation of each feature line, new NURBS curve nodes are obtained again using the isoparametric partitioning method, i.e., the same parameter partitioning {u′ k Let k = 0, 1, ..., n′. Find n+1 nodes on each feature line. The parameter separator is an empirical value, which can generally be selected according to the actual ship type, etc. Then, using these nodes as known points, reconstruct each feature curve again, that is, calculate according to the iterative calculation formula of NURBS curve, thereby adjusting the node distribution of each feature curve to have the same node vector. Therefore, a ship type NURBS surface can be further generated.

[0089] The generated NURBS surface of the ship shape and the bottom surface (defined by straight lines) are then spliced ​​together to obtain the parametric geometric model of the entire ship shape.

[0090] In one embodiment of the present invention, the subset of local deformation parameters of the hull includes a subset of reduced-order NURBS parameters of the hull and a subset of hull region parameters, wherein,

[0091] Adjustment control points are generated based on the hull-downgraded NURBS parameter subset and the hull region parameter subset.

[0092] A radial basis interpolation function is used to generate new NURBS surface control points based on the adjusted control points. Based on the new NURBS surface control points, the NURBS expression of the modified ship shape surface is obtained through NURBS surface calculation to generate the hull surface.

[0093] The surface generation process is based on a parent ship or a similar ship type, specifically the parent ship selected above. Changes in the main contour drive surface changes, generating a new ship type surface. A key feature is fitting the hull surface to the input original ship type using a reduced-order unified NURBS surface, thus reconstructing the hull surface. The reconstructed hull is a standard NURBS surface, allowing deformation via NURBS control points. Simultaneously, NURBS surface control points are coupled with the contour lines to achieve bidirectional, linked deformation. Specifically, the reduced-order NURBS surface represents a dimensionality reduction; in this case, the number of NURBS control points is less than the number of shape value points, reducing the number of parameters.

[0094] The bidirectional linkage deformation of the NURBS surface control points and contour lines is mainly based on the interpolation of radial basis functions to achieve bidirectional transmission of deformation. The NURBS control points and the main contour points together form a point set. When a specified displacement is applied to any number of points in the point set, it is transmitted to other points through radial basis function interpolation, thereby realizing the linkage design of the overall surface and contour.

[0095] Specifically, the method of generating adjustment control points can be consistent with the existing one. The deformation amount is bidirectionally transferred based on the interpolation of radial basis functions. Specifically, the deformation method based on the interpolation of radial basis functions is directly applied to the control points of the NURBS surface, so that the curve / surface formed by the NURBS control points is deformed, and the deformed ship-shaped surface is calculated according to the NURBS surface equation.

[0096] In one embodiment of the present invention, when the structure is a hydrodynamic energy-saving device, a propeller, or a high-efficiency rudder, the parametric geometric model of the structure is constructed using a fully parametric method based on airfoil profiles.

[0097] When constructing an airfoil using a fully parametric approach based on its airfoil profile, the geometric representation of the airfoil profile is controlled by the shape of the arch and the thickness distribution.

[0098] Specifically, the parametric geometric models of the propeller, high-efficiency rudder, and hydrodynamic energy-saving device uniformly adopt a fully parametric construction method based on airfoil profiles. The propeller blades, rudder profiles, guide wheels of the energy-saving device, and stator are all airfoil-like forms, and their blade profiles can be selected from existing airfoil families based on experimental or computational data, primarily based on airfoil lift-to-drag ratio and cavitation performance. The geometric expression of the airfoil profile is mainly controlled by the camber shape (f / c) and thickness distribution (t / c). Specifically, a blade profile refers to an airfoil profile at a certain cross-section, such as the propeller blade profile, the rudder blade profile at a certain height of the high-efficiency rudder, the cross-sectional blade profile of the energy-saving duct within the hydrodynamic energy-saving device, and the stator blade cross-sectional profile, etc.

[0099] In the traditional modeling process of propellers, high-efficiency rudders, and hydrodynamic energy-saving devices, airfoils are generally selected directly from existing airfoil families. With the development of refined design requirements, in one embodiment of the present invention, the parametric design of the airfoil profile is characterized by providing a parametric adjustment method for the distribution of the camber and thickness along the chord length of the airfoil.

[0100] Specifically, the parametric adjustment process for the airfoil profile involves the following steps:

[0101] Obtain the camber and thickness distribution curves of the airfoil from the airfoil family, and interpolate to obtain a refined camber and thickness distribution along the chord length;

[0102] The radial basis function (RBF) interpolation method is used to construct a 3D curve / surface deformation function to achieve parametric deformation design of feature lines: By selecting a basis function (the basis function can be a commonly used kernel function) and setting deformation design parameters (control fixed point, control moving point and displacement), a specified deformation region on the original target curve / surface is specified. Within the deformation region, the coordinates of the control point and the deformation amount along the X / Y / Z directions at the control point are set by customizing the control point coordinates. The change in shape value within the specified deformation region is obtained by simultaneously solving the displacement equations at the control point. This change is then superimposed on the original curve / surface to obtain the deformed 3D curve / surface.

[0103] By combining the original curve and the control point set, the radial basis function method is used to obtain the modified parameter distribution, and then the modified parameter distribution curve is obtained.

[0104] As explained above, the airfoil family provides the airfoil selection, from which the camber and thickness distribution curves of the corresponding airfoil profile can be obtained. Subsequently, interpolation can be performed using methods commonly used in this technical field, such as cubic spline curve interpolation, to obtain a more refined camber and thickness distribution along the chord length. Here, "refinement" specifically refers to increasing the density of the distribution.

[0105] After obtaining the results of the encrypted camber and thickness curves distributed along the chord length through interpolation, design variables are set based on radial basis functions (RBF). Specifically, the modified design method based on RBF designates several points on the curve as control points, and applies a forced displacement to each control point. For example, the bow and stern points of the curve must be control points. After the control points are forcibly displaced, they can drive other points on the curve to move accordingly, forming a new parametric curve.

[0106] Based on the airfoil profile design, principal dimension design parameters are set for the specific characteristics and engineering implementation requirements of the propeller, high-efficiency rudder, and energy-saving device to obtain the specific configuration geometry. These principal dimension design parameters are the principal parameters of each component; for example, for a propeller, these include the number of blades, blade diameter, and hub diameter, which are specifically related to the type of component and are well-known to those skilled in the art.

[0107] The parametric design process for the propeller, given a fixed airfoil, follows conventional parametric design practices, utilizing key dimensions such as the number of blades (Z) and diameter (D), as well as pitch distribution (P / D), maximum camber distribution (F / D), maximum thickness distribution (T / D), and sideslip distribution (θ). s ), longitudinal tilt distribution (Z) r The distribution of six radial parameters ( / D) enables the geometric construction of propeller blades.

[0108] The radial distribution curve of the parameters can be adjusted according to the design parameters at typical locations, such as the blade root, blade tip, and pitch and maximum camber at a radius of 0.7R, using the curve modification design method to achieve parametric modeling of the entire propeller blade.

[0109] The main steps of the propeller parametric design process are as follows:

[0110] Input the main propeller parameters, control parameters for the key radial position, and hub parameters. The main propeller parameters include the number of blades, diameter, and hub diameter ratio, which describe the main dimensional characteristics of the propeller blades. The control parameters are the pitch, maximum camber, maximum thickness, skew, and pitch parameters at the key radius (generally 0.5, 0.7, or 1.0 radii, which can be set according to specific circumstances). The hub parameters include the hub length, large end radius, small end radius, and distance from the large end to the reference surface.

[0111] According to the engineering design requirements, a reference airfoil profile is selected from the wing family, and the profile form is adjusted based on RBF parameterization.

[0112] The radial distribution curve of the pitch is constructed or adjusted by RBF parameterization;

[0113] Based on the reference airfoil profile and the pitch and camber at different radii, generate blade profiles at different radii;

[0114] Based on NURBS curved envelope, the least squares method is used to fit the profile to form a complete smooth blade surface;

[0115] The Brep expression method is used to generate blade entities based on the blade surface;

[0116] Construct the propeller hub solid;

[0117] Perform Boolean operations on the geometric solids of the blades and hub to obtain the overall geometric solid and export the file.

[0118] Specifically, the main propeller parameters, control parameters for key radial positions, and hub parameters are input to obtain the propeller design parameters. The reference airfoil profile specifically refers to the original airfoil profile before RBF deformation. Brep is used to facilitate subsequent geometric Boolean operations. Curves and surfaces in the Brep geometric model are represented by mathematical equations, allowing for operations such as intersection and union calculations.

[0119] In one embodiment of the present invention, the parameterized design process of the high-efficiency rudder is basically the same as the propeller modeling process, but its configuration is relatively simple. The difference lies in that it consists of two parts: the rudder body and the rudder ball. The main steps are briefly described as follows:

[0120] Input the main parameters of the rudder type, chord length, torsional camber at key locations, and maximum thickness;

[0121] According to the engineering design requirements, a reference airfoil profile is selected from the wing family, and the profile form is adjusted based on RBF parameterization.

[0122] The radial distribution curves of parameters such as pitch are parameterized using RBF.

[0123] Generate rudder profiles at different rudder height positions;

[0124] Based on NURBS curved envelope, the least squares method is used to fit the profile to form a complete smooth blade surface;

[0125] The rudder entity is generated based on the blade surface using the Brep expression method;

[0126] Input the rudder ball control parameters (major diameter, minor diameter, and section lines) to generate a rudder ball sketch;

[0127] Rotate to generate the rudder ball surface, and then generate the rudder ball solid;

[0128] Perform Boolean operations on the rudder and rudder ball to obtain the overall geometry and export the file.

[0129] The parametric design process for the rudder is basically the same as that for the propeller modeling process. The geometric feature parameters are shown in Table 2. Its shape is relatively simple, and the core lies in the parameterization of arbitrary rudder profiles. By representing the rudder profile coordinates as a function of the profile thickness distribution and camber distribution, and establishing its relationship with global design parameters, parametric modeling and design of the rudder's geometric shape can be achieved.

[0130] The parametric design process of the propeller-initiated energy-saving guide wheel has geometric characteristic parameters as shown in Table 3. Its geometric configuration consists of N stator blades and one duct, which can be omitted. Both the blades and the duct are constructed with basic airfoil profiles, and the parametric design of the profile geometry is consistent with that of the propeller and rudder.

[0131] Table 1 Geometric characteristic parameters of the propeller

[0132]

[0133] Table 2. Rudder Geometric Characteristic Parameters

[0134]

[0135]

[0136] Table 3 Geometric parameters of the propeller pre-spin guide wheel

[0137] dctLen duct chord length m dctAngle catheter inclination Degree dctDz catheter vertical axis length m dctDy catheter transverse axis length m dctX0 Distance from duct outlet to station 0 m saCantR(i) stator mounting angle i Degree saTiltRtR(i) Angle of attack at the root of stator number i Degree saTiltTpR(i) The angle of attack of the i-th stator tip Degree saCdRtR(i) Length of the root chord of stator i m saCdTpR(i) chord length of the i-th stator tip m saLen(i) Stator extension length of number i m

[0138] In one embodiment of the present invention, during the parametric design of the hydrodynamic energy-saving device, the device consists of N stator blades and one guide wheel, which may be omitted. Both the blades and the guide wheel are constructed using a basic airfoil profile, and the parametric design of the profile geometry is consistent with that of the propeller and rudder. The main steps are briefly described below:

[0139] Input the main design parameters of the hydrodynamic energy-saving device;

[0140] Select a reference airfoil profile and adjust the profile shape based on RBF parameterization;

[0141] Generate the stator key location airfoil and the duct key location airfoil for each stator;

[0142] The NURBS curved envelope was used to fit the profile to form a complete smooth stator blade surface;

[0143] Generate the sweep generatrix of the duct surface based on the input parameters, and generate the duct surface by combining the profile.

[0144] Perform Boolean operations on the stator and guide wheels to obtain the overall geometry and export the file.

[0145] Furthermore, the set of prior constraint problems includes:

[0146] The stator blades of the hydrodynamic energy-saving device are subject to distance constraints from the lowest point of the hull to the lower edge of the ship in the reference coordinate system: l HD <L HD L HD For the specified constraint parameters;

[0147] The distance x between the reference surface of the hydrodynamic energy-saving device and the stern shaft outlet planeD >0;

[0148] Propeller blade tip distance from the reference plane to the lower edge of the hull is constrained as follows: l HP <L HP , where L HP For the specified constraint parameters;

[0149] The rudder blades do not intersect with the propeller.

[0150] As explained above, prior constraints refer to the constraint range of given characteristic quantities in the design input conditions. Generally, prior constraint characteristic quantities are also input parameter quantities for geometric parametric design. Therefore, parameter values ​​within the constraint range can be specified as input parameter values ​​of corresponding characteristic quantities in the integrated design process of geometric components.

[0151] After determining the spatial relationships and constraints, the solution process for the associated constraint problem involves the following steps: First, obtaining the geometric configuration that satisfies the design parameters based on the parametric geometric model; second, performing coordinate system transformation and adjusting the installation position and angle based on the prior constraints; and finally, determining whether the posterior constraints are satisfied. If satisfied, performing multi-body Boolean operations to obtain the geometric configuration of the integrated energy-saving propulsion system; otherwise, returning to adjust the design parameters and constraints until they are satisfied.

[0152] Based on the geometric model of the above-mentioned structure, the physical representation of the integrated energy-saving propulsion system of the ship is generated, and multi-body Boolean operations are performed to complete the parametric design of the integrated energy-saving propulsion system of the ship after the multi-body Boolean operations.

[0153] In one embodiment of the present invention, the Brep expression method is adopted to generate geometric entities based on curved surfaces. The positions are configured by the positioning information of each ship appendage, and Boolean intersection operation is performed on the interfaces to obtain the geometric program input that can be directly configured into a mesh file by the post-processing software.

[0154] Specifically, multi-body Boolean operations, performing Boolean operations (union) on different geometric structures, can yield a geometric scheme for a unified system including the ship's propeller and rudder energy-saving devices. This facilitates subsequent meshing and performance calculations in CFD software.

Claims

1. A parametric design method for an integrated energy-saving propulsion system for ships, characterized in that, The parametric design method includes: For a parametrically designed integrated energy-saving propulsion system for a ship, determine the reference coordinate system of the integrated energy-saving propulsion system for the ship; The above-mentioned integrated energy-saving propulsion system for ships is structurally divided into several structural components, wherein the divided structural components include at least the hull, hydrodynamic energy-saving device, propeller and high-efficiency rudder. For the aforementioned integrated energy-saving propulsion system for ships and the divided structural bodies, a parameter set is designed. The designed parameter set includes a subset of geometric design parameters corresponding to each structural body and a subset of associated constraint problem parameters used to characterize the associated constraint conditions. The subset of associated constraint problem parameters includes a set of prior constraint problems corresponding to each structural body and a set of posterior constraint problems corresponding to the integrated energy-saving propulsion system for ships. For any construct, a parametric geometric model of the construct is generated. When generating the parametric geometric model, the parametric geometric model of the construct is constructed sequentially based on the corresponding subset of geometric design parameters and the set of prior constraint problems. After constructing the parametric geometric model of all the constructs, the posterior constraint characteristic quantities of the integrated energy-saving propulsion system of the ship are solved based on the set of posterior constraint problems. When the posterior constraint feature quantity does not match the posterior constraint target feature quantity, the above-mentioned geometric design parameter subset is adjusted, and the above-mentioned posterior constraint feature quantity solution is repeated after adjusting the above-mentioned geometric design parameter subset until the posterior constraint feature quantity matches the posterior constraint target feature quantity. Based on the geometric model of the above-mentioned construct, a physical integrated energy-saving propulsion system for the ship is generated, and multi-body Boolean operations are performed to generate the target integrated energy-saving propulsion system for the ship after the multi-body Boolean operations. The set of prior constraint problems includes: The stator blades of the hydrodynamic energy-saving device are subject to distance constraints from the lower edge of the hull at their highest point in the reference coordinate system. ,in For the specified constraint parameters; Distance between the reference surface of the hydrodynamic energy-saving device and the stern shaft outlet plane ; Constraints on the distance between the propeller blade tip and the lower edge of the hull at the reference plane: ,in, For the specified constraint parameters; The rudder blades do not intersect with the propeller.

2. The parametric design method for the integrated energy-saving propulsion system of ships according to claim 1, characterized in that, When the structure is a ship hull, the subset of geometric design parameters for the hull includes a subset of global structural parameters and a subset of local deformation parameters. The method for generating the parametric geometric model of the hull includes: The main outline of the hull is generated based on a subset of global hull construction parameters. NUBRS surface control points of the hull are generated based on a subset of local deformation parameters of the hull. Associate the NUBRS surface control points of the hull with the main contour of the hull, and generate the hull surface after association. The NUBRS surface of the hull is generated based on the above-mentioned hull surface. When the generated NUBRS surface satisfies the set of prior constraints of the hull, the NUBRS surface is configured as the parametric geometric model of the hull.

3. The parametric design method for the integrated energy-saving propulsion system of ships according to claim 2, characterized in that, The global construction parameter subset includes a principal dimension parameter set and a hull feature line parameter set defined based on NURBS curves. When generating the main contour of the hull based on the global construction parameter subset, the process includes: Construction control points for curves based on the set of principal scale parameters and the set of hull feature line parameters; Deformation control points are obtained based on the construction control points of the curve and the NURBS curve order constraints. A set of control points is generated based on the construction control points and deformation control points, and a NURBS feature curve is generated. In the generated NURBS feature curve, the straight line segments are directly generated by the construction control points, and the straight line segments and curve segments are spliced ​​together to form the main outline of the hull.

4. The parametric design method for the integrated energy-saving propulsion system of ships according to claim 2, characterized in that, The subset of local deformation parameters for the hull includes a subset of reduced-order NURBS parameters for the hull and a subset of hull region parameters, wherein... Adjustment control points are generated based on the hull-downgraded NURBS parameter subset and the hull region parameter subset. A radial basis interpolation function is used to generate new NURBS surface control points based on the adjusted control points. Based on the new NURBS surface control points, the NURBS expression of the modified ship shape surface is obtained through NURBS surface calculation to generate the hull surface.

5. The parametric design method for an integrated energy-saving propulsion system for ships according to any one of claims 1 to 4, characterized in that, When the structure is a hydrodynamic energy-saving device, a propeller, or a high-efficiency rudder, the parametric geometric model of the structure is constructed using a fully parametric method based on airfoil profiles. When constructing an airfoil using a fully parametric approach based on its airfoil profile, the geometric representation of the airfoil profile is controlled by the shape of the arch and the thickness distribution.

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