Paddle parameterization design method and paddle parameterization three-dimensional model

Abstract

The invention discloses a blade parameterization design method which comprises the following steps: analyzing working conditions, selecting a proper rotor wing type, importing an airfoil profile file into a parameterization three-dimensional modeling platform, determining the number of airfoil profile sections, creating a sketch on an initial reference surface, projecting the sketch airfoil profile as an imported curve, and scaling, twisting and shifting the airfoil profile to obtain the blade parameterization three-dimensional modeling platform. And similarly, repeating the operation on the reference surfaces on the plurality of airfoil sections to complete the creation of the plurality of airfoil sections, and creating a spline curve by taking the front edge points of all the established airfoil sections as spline points, and setting out the setting-out cross section as a setting-out guide line, setting out the setting-out cross section and the guide line to generate a three-dimensional model, creating a blade tip feature of the blade, exporting a three-dimensional solid model, and completing parameterized design of the blade. The method is simple in logic, and can be manually or automatically realized through different parameterized three-dimensional modeling software; the application range is wide; meanwhile, the method is easy to implement through various high-level programming languages, and the convenience of data interaction with other programs is high.

Description

Technical Field

[0001] The present invention relates to the technical field of blade design, and in particular to a blade parametric design method and a blade parametric three-dimensional model. Background Art

[0002] Propeller blades are power components that rotate to propel fluid, generating a reaction force that creates thrust or pull. They are widely used in technical fields such as aircraft and ships. Propeller blades primarily drive the fluid by rotating their fluid-engaging surfaces, generating thrust or pull, which in turn drives the device. To achieve specific aerodynamic performance, blade optimization is an ongoing process. Most optimization efforts rely on parametric design of the blades, with further optimization based on the parameters of these parametric designs.

[0003] Patent number: 202211078376.5, the patent name is a propeller blade parameterization and surface generation method based on B-spline, which specifically discloses: First, based on the B-spline curve method, the least squares method is used to fit the blade section value points at different radii, and the proportion, offset, coordinate transformation and other methods are used to realize the parameterization of the blade section and shape contour; secondly, based on the B-spline surface method, the propeller blade surface, blade back, blade root and blade top surfaces are efficiently generated; finally, the relevant program writing is completed based on the Python language, and the UML class diagram of the program is given; the present invention uses the language Python to program the entire process to realize the parameterization of the propeller blade and automatic surface generation, which effectively improves the propeller modeling efficiency and the flexibility of parameterization variable selection in the optimization process.

[0004] The aforementioned existing patent is based on a B-spline curve method, employing the least squares method to fit blade section profile points at different radii. It also uses scaling, offsetting, and coordinate transformation methods to parameterize the blade section and profile. Furthermore, based on the B-spline surface method, it efficiently generates the propeller blade face, back, root, and tip surfaces. The implementation is written in Python. This method is relatively complex, and the optimization results are also limited by the B-spline curve, potentially avoiding certain optimal design outcomes.

[0005] At the same time, generally speaking, the parametric design of blades is mainly achieved through secondary development of parametric three-dimensional modeling platforms, but this implementation method may lead to problems such as limited design space or a large number of parameters. Summary of the Invention

[0006] In view of this, in order to optimize the number of parameters and control the geometric characteristics of the blades, the present invention realizes the high efficiency of blade parametric modeling and subsequent parameter optimization, and proposes a blade parametric design method and a blade parametric three-dimensional model.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A parametric design method for a blade includes the following steps:

[0009] Step 1: Analyze the operating conditions and determine the initial blade length and chord length;

[0010] Step 2: Select the appropriate rotor airfoil and generate a point set file based on the set chord length;

[0011] Step 3: Import the airfoil file into the parametric 3D modeling platform, ensuring that the imported curve is orthogonal to the reference coordinate system in the modeling platform, and the plane where the curve is located is the initial reference plane;

[0012] Step 4: Determine the number of airfoil sections, calculate the distance between each airfoil section and the initial reference plane based on the blade length and the airfoil section distance coefficient, and create reference planes parallel to the initial reference plane at these distance positions.

[0013] Step 5: Create a sketch on the initial reference plane. The sketched airfoil is a projection of the imported curve. Scale, twist, and offset the airfoil. Repeat the above operations on the reference planes of multiple airfoil sections to complete the creation of multiple airfoil sections.

[0014] Step 6: Create a spline curve using the leading edge points of all airfoil sections created in step 5 as spline points, which will serve as the guide line for lofting.

[0015] Step 7: Use the section sketch created in step 5 as the lofted section and the spline curve created in step 6 as the guide line to loft and generate a 3D model. The 3D model of the main aerodynamic surface of the blade is thus generated.

[0016] Step 8: Create the blade tip feature, and create the blade heel and flap hinge features according to the flap requirements;

[0017] Step 9: Export the 3D solid model to complete the parametric design of the blade.

[0018] As a further improvement of the above technical solution:

[0019] As a further optimization solution of the present invention, the scaling step in step 5 is: using the airfoil leading edge point of the airfoil section on the corresponding reference plane as the scaling reference point, scaling the sketch according to the scaling ratio of the airfoil section on the corresponding reference plane.

[0020] As a further optimization solution of the present invention, the twisting step in step 5 is: using the airfoil leading edge point of the airfoil section on the corresponding reference plane as the twist center, and transforming the twist angle of the airfoil sketch.

[0021] As a further optimization solution of the present invention, the torsion angle is calculated by the maximum pitch angle of the blade and the torsion ratio of the first section.

[0022] As a further optimization solution of the present invention, the offset step in step 5 is: the airfoil sketch on the corresponding reference plane is offset by a corresponding offset amount, and the offset amount is two coordinate systems.

[0023] As a further optimization scheme of the present invention, in step 81, the position of the three-dimensional entity is moved according to the installation requirements, and the entity is offset by the three-coordinate system offset so that the origin is located at the intersection of the blade rotation axis and the pitch hinge axis to facilitate subsequent simulation analysis.

[0024] The present invention also discloses a parametric three-dimensional model of a blade. The blade is formed by lofting a number of parallel airfoil sections maintained at a specific distance through three-dimensional modeling software. The position and size of each airfoil section are controlled by a combination of parametric variables. The blade thus generated can have different aerodynamic surface characteristics.

[0025] As a further improvement of the above technical solution:

[0026] As a further optimization scheme of the present invention, the parameterized variable combination includes airfoil section distance coefficient, section scaling ratio, section torsion ratio, section offset X, section offset Y, blade length, blade maximum pitch angle, and number of sections.

[0027] As a further optimization scheme of the present invention, a parameter simplification method is also provided, specifically: integrating parameters through a proxy model, introducing a relaxation factor to change the parameter variable group, and allowing the changes of the original parameter variable combination to be controlled by fewer parameter variables of the proxy model.

[0028] As a further optimization solution of the present invention, the proxy model is specifically as follows:

[0029] f(x)=a(xh) 3 +b(xw) 2 +cx+d;

[0030] Where x represents the dependent variable, which is the airfoil section distance coefficient in the surrogate model; f(x) is the change in the section scaling ratio (SE) around the initial value; h and w are two relaxation factors used to control the specific dependent variable; a, b, c, and d are constants of the surrogate model polynomial.

[0031] Compared with the existing technology, the beneficial effects of the present invention are:

[0032] 1. The method of the present invention has simple logic and can be implemented manually or automatically through different parametric 3D modeling software; it has a wide range of applications; at the same time, the method of the present invention can be easily implemented through various high-level programming languages, and has high convenience in data interaction with other programs;

[0033] 2. The method for updating parameters based on a surrogate model provided by the present invention greatly reduces the number of parameters in the optimization design and saves computing resources. Furthermore, the initial value of the surrogate model is based on the actual blade in use, and the parameter update is performed based on its fitting parameters, which can make subsequent optimization more efficient.

[0034] 3. The design parameters used in the present invention are purely geometric parameters, which can be freely transformed within a set range and have good adaptability to the optimization algorithm based on deep learning of neural networks;

[0035] 4. The parametric design method of the present invention is based on parameter-based parametric 3D modeling software, and the design model generated by the parametric design method can be directly used in various finite element analysis software. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of the blade parameterized model structure of the present invention;

[0037] Figure 2 This is a schematic diagram of the transformation of the blade airfoil cross-section sketch of the present invention;

[0038] Figure 3 This is a flow chart of the blade parameter design method of the present invention. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0040] In the description of the present invention, unless otherwise specified, "plurality" means two or more; terms such as "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," and "tail" indicate positions or relationships based on those shown in the accompanying drawings. These terms are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Furthermore, terms such as "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0041] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integral connection; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0042] Example 1

[0043] This technical solution discloses a parameterized three-dimensional model of a blade, as shown in the attached Figure 1 With attached Figure 2 As shown, the parametric blade model is formed by lofting a number of parallel airfoil sections at a specific distance through 3D modeling software. The position and size of each airfoil section are controlled by a number of parameters, and the blade generated thereby can have different aerodynamic surface characteristics.

[0044] The specific parameterized variable combinations include: airfoil section distance coefficient (BLE), section scaling ratio (SE), section twist ratio (RE), section offset X (LEX), section offset Y (LEY), blade length (Bladelong), blade maximum pitch angle (Degp), and number of sections (N).

[0045] 1. The blade length (Bladelong), maximum blade pitch angle (Degp), and number of sections (N) can be input by the designer as needed, and can also be used as pre-parameters for other parameter variables for update and iteration.

[0046] 2. The airfoil section distance coefficient (BLE) controls the airfoil, including BLE1, BLE2, BLE3, ..., BLEN. The number of BLE is equal to the number of sections. It represents the ratio of the distance from the section of the airfoil to the initial reference plane to the blade length (Bladelong).

[0047] The initial reference plane is the plane passing through the origin; the BLE1 coefficient is 0, and the first airfoil section coincides with the initial reference plane, and BLEN is the end airfoil section.

[0048] 3. Section scaling (SE) controls the scaling ratio of each section of the airfoil relative to the initial airfoil. The section scaling ratios of each section are: SE1, SE2, SE3, ..., SEN. The scaling center point can be customized. This technical solution selects the leading edge point of the airfoil as the scaling center of the airfoil section.

[0049] 4. The section torsion ratio (RE) controls the ratio of the torsion angle of each section airfoil to the maximum pitch angle of the blade (Degp), specifically including: RE1, RE2, RE3, ..., REN. The torsion center of the airfoil section can be a custom coordinate point. The torsion center of this technical solution is defined as the leading edge point of the airfoil.

[0050] 5. Section Offset X (LEX) and Section Offset Y (LEY) control the offset of each airfoil section within the plane. The coordinate offsets for each airfoil section are: (LEX1, LEY1), (LEX2, LEY2), (LEX3, LEY3), ..., (LEXN, LEYN). With the leading edge of the initial blade as the origin, the section offsets are the coordinates of the leading edge of each airfoil section.

[0051] The above parameters are all design variables. For example, the relevant parameters are explained as follows:

[0052] If the distance control coefficients are 0, 0.5, and 1, then the three control sections are evenly distributed;

[0053] The SE scaling factor is 1, so the airfoil sizes of the three sections are the same.

[0054] The RE twist proportional coefficient is 1, so the twist angle of all airfoils is the maximum angle set at the beginning;

[0055] If LEX and LEY are both set to 0, the offsets of the three airfoils will also be 0.

[0056] These values are all parameters of the parametric model. Using these parameters with a specific airfoil can represent the blade we want. The more cross-sections there are, the higher the accuracy of the blade shape.

[0057] The above parameters are manually specified. The data source can be the initial values specified according to their meanings, or the parameter values obtained by fitting existing blades. These parameters directly control the profile of the blade.

[0058] Example 2

[0059] For the parameterized three-dimensional model established by Example 1, if it needs to be optimized, it is only necessary to change a specific parameter variable combination to perform the optimization. Therefore, the present technical solution integrates the parameters through a proxy model and introduces a relaxation factor to change the parameter variable group, allowing the changes of the original parameter variable combination to be controlled by fewer parameter variables of the proxy model.

[0060] For example, if the blade to be optimized is known, the above parameter design model can be used to fit the blade and obtain the initial values of all the above parameters. The airfoil section distance coefficients (BLE) controlling the airfoil are known to include: BLE1, BLE2, BLE3, ..., BLEN, and the section scaling (SE) is known to include: SE1, SE2, SE3, ..., SEN. Using the known data [(BLE1, SE1), (BLE2, SE2), (BLE3, SE3), ..., (BLEN, SEN)], a high-order polynomial surrogate model containing relaxation factors is constructed. As an example, the constructed third-order surrogate model is as follows:

[0061] f(x)=a(xh) 3 +b(xw) 2 +cx+d

[0062] Wherein, x represents the dependent variable, which is the airfoil section distance coefficient (BLE) in the proxy model. Each section scaling ratio (SE) can be calculated by the airfoil section distance coefficient (BLE) of its corresponding section through the above proxy model; h and w are two relaxation factors used to control the change of f(x), i.e., the section scaling ratio (SE), around the initial value under a specific dependent variable, and a, b, c, d are constants of the proxy model polynomial. Preferably, when the two relaxation factors h and w are set to 0, the calculated section scaling ratio (SE) is set as the initial value, and the generated blade is the initial fitting blade. With the change of the two parameters h and w, the value of f(x) changes within a certain range of the initial value, that is, the change of N parameter variables is achieved through the update iteration of the two relaxation factors.

[0063] Similarly, other parameter variable groups can be updated and iterated through the proxy model.

[0064] Using the proxy model approach described above to correlate parameters actually reduces these parameters to a certain extent, but the variation of these parameters is limited by the proxy model. This technical solution only designs a proxy model for the relationship between the airfoil section distance coefficient and the cross-sectional scaling ratio. Independent proxy models can also be constructed for other parameter models to complete the relationship between them and the airfoil section distance coefficient. It is necessary to summarize the regularities between the parameters and introduce new relaxation factors.

[0065] When optimizing the design based on the parametric model of the present invention, these manually initialized parameters will be updated and iterated to find the best parameter combination; sometimes, in order to save computing time, a proxy model will be used, and only the variables of the proxy model will be updated to indirectly control the parameters of the parametric model and complete the model update in one go.

[0066] Although the design parameters are greatly reduced, the design space is also greatly reduced, and the surrogate model will be very complex, making it difficult to obtain effective optimization design results.

[0067] Using a proxy model for parameter iteration: The advantages are small computational complexity and fast computation time, but the disadvantages are: general optimization effect and significant limitations on the optimization results;

[0068] Compared with direct iteration using advanced algorithms (including neural network algorithms): the advantage is better optimization effect and fewer restrictions; the disadvantage is large amount of calculation and longer calculation time.

[0069] Example 3

[0070] Based on the parameterized three-dimensional model of the blade established in Example 1, this technical solution designs a design scheme for the parameterized three-dimensional model of the blade, as shown in the attached figure. Figure 3 The specific steps are as follows:

[0071] Step 1: Analyze the working conditions and determine the initial blade length and initial chord length;

[0072] Step 2: Select the appropriate rotor airfoil and generate a point set file based on the set chord length;

[0073] Step 3: Import the airfoil file into the parametric 3D modeling platform, ensuring that the imported curve is orthogonal to the reference coordinate system in the modeling platform, and the plane where the curve is located is the initial reference plane;

[0074] Step 4: Determine the number of airfoil sections N based on design accuracy and efficiency. Calculate the distances D1, D2, D3, ..., DN of each airfoil section from the reference plane based on the blade length (Bladelong) and the airfoil section distance coefficient (BLE). Create reference planes parallel to the initial reference plane at these distances.

[0075] Step 5: Create a sketch on the first reference plane. The sketch airfoil is a projection of the imported curve. The airfoil is scaled with the scaling ratio of the first section (SE1). The scaling reference point is the leading edge point of the airfoil. The preferred leading edge point of the first airfoil section is (0,0,D1). Furthermore, the airfoil sketch is twisted with the leading edge point (0,0,D1) as the twist center. The twist angle is calculated by the maximum blade pitch angle (Degp) and the first section twist ratio (RE1). Furthermore, the airfoil sketch is offset with an offset of (LEX1,LEY1).

[0076] Similarly, create a sketch on the second datum plane. Similar to the process for creating a sketch on the first datum plane, create a sketch by importing the airfoil curve projection. Use the leading edge point (0,0,D2) as the reference point and scale the sketch according to the second section scaling ratio (SE2). Also using this point as the reference point, twist the sketch using the angle calculated by the maximum blade pitch angle (Degp) and the second section twist ratio (RE2). Offset the sketch using the offset (LEX2,LEY2). This completes the creation of the second airfoil sketch.

[0077] Repeat the above steps to complete the creation of the 3rd, 4th, ..., Nth airfoil sections in sequence.

[0078] Step 6: Create a spline curve using the leading edge points of all the above airfoil sections ((LEX1,LEY1,D1),(LEX1,LEY1,D1),(LEX1,LEY1,D1),…,(LEXN,LEYN,DN)) as spline points, and use them as the guide line for lofting;

[0079] Step 7: Use the section sketch created in step 5 as the lofted section and the spline curve created in step 6 as the guide line to generate a 3D model. The 3D model of the main aerodynamic surface of the blade is generated.

[0080] Step 8: Move the position of the 3D entity according to the installation requirements. The entity offset is (a, b, c) so that the origin is located at the intersection of the blade rotation axis and the pitch hinge axis to facilitate subsequent simulation analysis.

[0081] Step 9: Create the blade tip feature, and create the blade heel and flap hinge features according to the flap requirements;

[0082] Step 10: Export the 3D solid model to complete the parametric design of the blade.

[0083] The above design scheme can be realized by manually operating the parametric three-dimensional modeling software, or the parametric modeling software can be secondary developed through high-level programming languages including but not limited to VBA, Python, C#, etc.

[0084] The blade parameterization general high-level language program based on the above method can interact with various optimization algorithms for data, including but not limited to various advanced algorithms including neural network algorithms.

[0085] The above are only preferred specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A parametric design method for blades, characterized in that: The following steps are involved: Step 1: Analyze the operating conditions and determine the initial blade length and chord length; Step 2: Select the appropriate rotor airfoil and generate a point set file based on the set chord length; Step 3: Import the airfoil file into the parametric 3D modeling platform, ensuring that the imported curve is orthogonal to the reference coordinate system in the modeling platform, and the plane where the curve is located is the initial reference plane; Step 4: Determine the number of airfoil sections, calculate the distance between each airfoil section and the initial reference plane based on the blade length and the airfoil section distance coefficient, and create reference planes parallel to the initial reference plane at these distance positions. Step 5: Create a sketch on the initial reference plane. The sketched airfoil is a projection of the imported curve. Scale, twist, and offset the airfoil. Repeat the above operations on the reference planes of multiple airfoil sections to complete the creation of multiple airfoil sections. Step 6: Create a spline curve using the leading edge points of all airfoil sections created in step 5 as spline points, which will serve as the guide line for lofting. Step 7: Use the section sketch created in step 5 as the lofted section and the spline curve created in step 6 as the guide line to loft and generate a 3D model. The 3D model of the main aerodynamic surface of the blade is thus generated. Step 8: Create the blade tip feature, and create the blade heel and flap hinge features according to the flap requirements; Step 9: Export the 3D solid model to complete the parametric design of the blade.

2. The blade parameter design method according to claim 1, characterized in that: The scaling step in step 5 is: using the airfoil leading edge point of the airfoil section on the corresponding reference plane as the scaling reference point, scaling the sketch according to the scaling ratio of the airfoil section on the corresponding reference plane.

3. The blade parameter design method according to claim 1, characterized in that: The twisting step in step 5 is: using the airfoil leading edge point of the airfoil section on the corresponding reference plane as the twist center, and transforming the twist angle of the airfoil sketch.

4. The blade parameter design method according to claim 3, characterized in that: The torsion angle is calculated from the maximum pitch angle of the blade and the torsion ratio of the first section.

5. The blade parameter design method according to claim 1, characterized in that: The offset step in step 5 is: performing sketch offset on the airfoil sketch on the corresponding reference plane by a corresponding offset amount, where the offset amount is in two coordinate systems.

6. The blade parameter design method according to claim 1, characterized in that: Step 81: Move the position of the three-dimensional entity according to the installation requirements, and offset the entity by the three-coordinate system offset so that the origin is located at the intersection of the blade rotation axis and the pitch hinge axis to facilitate subsequent simulation analysis.

7. A parameterized three-dimensional model of a blade, characterized in that: The blades are formed by lofting a number of parallel airfoil sections at a specific distance through 3D modeling software. The position and size of each airfoil section are controlled by a combination of parametric variables. The resulting blades can have different aerodynamic surface characteristics.

8. The parameterized three-dimensional model of the blade according to claim 7, characterized in that: The parameterized variable combination includes an airfoil section distance coefficient, a section scaling ratio, a section twist ratio, a section offset X, a section offset Y, a blade length, a blade maximum pitch angle, and the number of sections.

9. The parameterized three-dimensional model of the blade according to claim 8, characterized in that: A parameter simplification method is also provided, specifically: integrating parameters through a proxy model, introducing a relaxation factor to change the parameter variable group, and allowing the changes in the original parameter variable combination to be controlled by fewer parameter variables of the proxy model.

10. The parameterized three-dimensional model of the blade according to claim 9, characterized in that: The proxy model is as follows: f(x)=a(*-h) 3 +b(x-w) 2 +cx+d; Where x represents the dependent variable, which is the airfoil section distance coefficient in the surrogate model; f(x) is the change in the section scaling ratio around the initial value; h and w are two relaxation factors used to control the specific dependent variable; a, b, c, and d are constants of the surrogate model polynomial.

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