Turbine blade parametric modeling method and system based on blade end wall integrated design

Abstract

The invention belongs to the technical field of turbine blade design. The invention provides a turbine blade parametric modeling method and system based on blade end wall integrated design. According to the embodiment of the invention, the NFFD mesh is adopted to directly generate the complete geometric profile of the three-dimensional turbine blade, so that the high-order smooth transition between the blade and the end wall is easy to realize. According to the method, local geometric modification of the blade is supported, abundant geometric modification deformation parameters are provided, the adjustment range of the parameters is conveniently determined, and it is ensured that unreasonable geometric shapes cannot occur. In the optimization design process, additional constraint conditions do not need to be set, and therefore the flexible and efficient optimization process is achieved. In addition, the method is suitable for the modeling and parameterization process of the axial flow turbine blades with various purposes, and has a good regulation and control effect on the secondary flow of the end area.

Description

Technical Field

[0001] The disclosed embodiments relate to the technical field of turbine blade design, and in particular to a parametric modeling method and system for turbine blades based on blade end wall integrated design. Background Art

[0002] As high-performance axial-flow turbines continue to pursue high loads, high efficiency, and high reliability, blade design has become one of the key factors in improving turbine performance. In this context, the concept of blade endwall fusion design came into being, further promoting the development of turbine technology. This design concept aims to start from the source of design, deeply consider the aerodynamic relationship between turbine blades, endwalls, and flow channels, and reduce flow losses and improve the overall efficiency of the turbine by optimizing the airflow path and improving the flow distribution. The blade endwall integrated design method is an important way to achieve blade endwall fusion design. This method directly obtains the airflow channel by stacking the vertical streamline sections at different flow positions, and then obtains the blade geometry through the entity surrounded by two adjacent airflow channels. This design method can greatly improve the problem of flow deterioration in the blade / endwall corner area caused by traditional design methods, and actively consider the regulation of the end area flow from the beginning of the design, which is expected to significantly reduce the secondary flow loss in the turbine end area.

[0003] However, the existing blade end wall integrated design method only realizes the shape of the flow channel by constructing the shape of each cross section of the flow channel, and the parameterization work is relatively small, resulting in the problem of controlling variables that has not been effectively solved. The current design method mainly relies on line generation surface, and is therefore not sensitive enough to the regulation of geometric shapes. This situation makes it difficult to flexibly adjust the geometry of the flow channel in the subsequent optimization design process, limiting the design potential and efficiency.

[0004] Therefore, it is necessary to improve one or more problems existing in the above-mentioned related technical solutions.

[0005] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0006] The purpose of the embodiments of the present disclosure is to provide a parametric modeling method and system for turbine blades based on the integrated design of the blade end wall, thereby overcoming one or more problems caused by the limitations and defects of the relevant technology at least to a certain extent.

[0007] According to a first aspect of an embodiment of the present disclosure, a method for parameterized modeling of a turbine blade based on blade end wall integrated design is provided, the method comprising:

[0008] The geometric data of the prototype blade is obtained, and the blade profile of the prototype turbine blade is transformed into a coordinate according to the geometric data and the rotation surface to obtain a plane straight blade;

[0009] According to the plane straight blade, the median arc line of each radial cross-section of the straight blade is obtained;

[0010] The direction of the flow channel along each section is determined according to the slope distribution of the mid-arc line of each radial section of the blade of the straight blade, and the number of flow channel sections is set to determine the segmentation trajectory of each section of the flow channel;

[0011] The coordinates of the discrete points of each section of the flow channel are extracted according to the segmentation trajectory of each section of the flow channel, and the control points of each section are obtained by combining the NURBS inverse algorithm, and the NFFD control grid is formed according to the control points of each section;

[0012] The initial shape of the turbine plane straight blade is generated according to the NFFD control grid, and the grid deformation is controlled by using the parameters of the NFFD control grid to modify the initial shape of the turbine plane straight blade to obtain the target shape of the turbine plane straight blade;

[0013] The target shape of the turbine plane straight blade is transformed into coordinates to obtain the geometry of the turbine blade on the rotating surface.

[0014] Further, the step of obtaining geometric data of the prototype blade and performing coordinate transformation on the turbine blade of the prototype blade according to the geometric data and the rotation surface to obtain a planar straight blade includes:

[0015] Obtain the geometric data of the prototype blade, determine the rotation surface, and convert the (x, y, z) coordinates of the discrete points of each cross-sectional blade of the prototype blade into (r, θ, z) coordinates;

[0016] Among them, x is the radial position of the blade, y is the circumferential position, and z is the axial position of the blade.

[0017] Further, according to the planar straight blade, the step of obtaining the camber line of each radial cross-section blade profile of the straight blade includes:

[0018] The blade profile is divided into the suction side and the pressure side according to the leading edge point and the trailing edge point, and the curvature distribution of the suction side and the pressure side is calculated respectively, and the sudden change of curvature is removed to obtain the pressure side and the suction side of the blade body;

[0019] The pressure side profile and suction side profile of the blade body are offset equidistantly for multiple times, and a number of intersection points are generated after each offset. The intersection points are arranged in axial order to form a point set to form the median arc line of each radial section of the straight blade.

[0020] Further, the step of determining the direction of the flow channel along each section according to the slope distribution of the mid-camber line of each radial section of the blade profile of the straight blade, and setting the number of flow channel sections to determine the segmentation trajectory of each section of the flow channel includes:

[0021] According to the preset number of flow channel sections n, the middle arc is divided according to the uniform chord length method to obtain the dividing points;

[0022] Determine the normal direction of the middle arc at each cutting point according to the distribution of the slope of the middle arc;

[0023] Solve the intersection points of the normal line and the pressure side profile of the blade, and the normal line and the suction side profile of the blade respectively, and arrange them axially;

[0024] The suction side and pressure side of each section of the blade are radially connected in axial order through the intersection of the normal line and the pressure side profile of the blade body and the normal line and the suction side profile of the blade body to obtain the cutting trajectory of each section of the flow channel.

[0025] Furthermore, the steps of extracting the coordinates of discrete points of each section of the flow channel according to the segmentation trajectory of each flow channel section, obtaining the control points of each section by combining the NURBS inverse algorithm, and forming the NFFD control grid according to the control points of each section include:

[0026] Extracting the coordinates of discrete points of each cross section of the flow channel according to the segmentation trajectory of each cross section of the flow channel;

[0027] Determine the node vector according to the coordinates of the discrete points of each cross section of the flow channel;

[0028] Construct non-uniform B-spline basis functions based on knot vectors;

[0029] Based on non-uniform B-spline basis functions and combined with NURBS inverse algorithm, the coefficient matrix and control point inverse equations are established to obtain the control vertices of each cross-sectional curve.

[0030] The control vertices of each cross-sectional curve are arranged along the blade flow direction to form a closed NFFD control grid.

[0031] Further, the step of generating an initial shape of the turbine plane straight blade according to the NFFD control grid, controlling grid deformation by using parameters of the NFFD control grid, and modifying the initial shape of the turbine plane straight blade to obtain a target shape of the turbine plane straight blade includes:

[0032] Generate the initial shape of the turbine plane straight blade based on the NFFD control grid;

[0033] When the control point is moved, the NFFD algorithm recalculates the coordinates of the shape value points of the turbine blade geometry according to the new positions of the control vertices of each cross-sectional curve;

[0034] By adding weights to local control points, the turbine blade details are modified to obtain the target shape of a turbine flat straight blade.

[0035] According to a second aspect of an embodiment of the present disclosure, a turbine blade parametric modeling system based on blade end wall integrated design is provided, the system comprising:

[0036] The first blade coordinate conversion module is used to obtain geometric data of the prototype blade, and to perform coordinate transformation on the turbine blade of the prototype blade according to the geometric data and the rotation surface to obtain a plane straight blade;

[0037] The blade geometry analysis module is used to obtain the median arc line of each radial section of the straight blade according to the plane straight blade;

[0038] The blade flow channel segmentation module is used to determine the direction of the flow channel along each section according to the slope distribution of the mid-arc line of each radial section of the blade of the straight blade, and set the number of flow channel sections to determine the segmentation trajectory of each section of the flow channel;

[0039] NFFD control grid generation module, used to extract the coordinates of discrete points of each section of the flow channel according to the segmentation trajectory of each flow channel section, obtain the control points of each section in combination with the NURBS inverse algorithm, and form the NFFD control grid according to the control points of each section;

[0040] A shape modification module is used to generate an initial shape of the turbine plane straight blade according to the NFFD control grid, and to control grid deformation by using parameters of the NFFD control grid to modify the initial shape of the turbine plane straight blade to obtain a target shape of the turbine plane straight blade;

[0041] The second blade coordinate conversion module is used to perform coordinate transformation on the target shape of the turbine plane straight blade to obtain the geometry of the turbine blade on the rotating surface.

[0042] The technical solution provided by the embodiments of the present disclosure may have the following beneficial effects:

[0043] In the embodiment of the present disclosure, through the above-mentioned turbine blade parametric modeling method and system based on the integrated design of blade end wall, on the one hand, the coordinates of the discrete points of each section of the prototype blade are obtained by using the acquisition module as the input of the processing module, and then the NFFD control grid is obtained by the processing module through coordinate transformation, blade geometry analysis and blade flow channel segmentation. The NFFD grid deformation parameters control the coordinate changes of each control point of the grid, and the weight of the control point is changed to achieve the deformation and fine regulation of the turbine blade geometry, and finally the output module outputs the final model that can be used for grid division. On the other hand, the NFFD (Non-Uniform Rational B-Spline Free-Form Deformation) grid is used to directly generate a complete three-dimensional turbine blade geometric profile, so that the high-order smooth transition between the blade and the end wall is easy to achieve. This method not only supports local modification of the blade geometry, but also provides a wealth of geometric modification deformation parameters, which is convenient for determining the adjustment range of the parameters and ensuring that no unreasonable geometric shapes will appear. In the optimization design process, no additional constraints need to be set, thereby realizing a flexible and efficient optimization process. In addition, this method is suitable for the modeling and parameterization process of axial flow turbine blades for various purposes, and has a good control effect on the secondary flow in the end area.

[0044] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are used to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0046] Figure 1 A diagram showing the steps of a turbine blade parameter modeling method based on blade end wall integrated design in an exemplary embodiment of the present disclosure;

[0047] Figure 2 A schematic diagram of a three-dimensional turbine guide vane in an exemplary embodiment of the present disclosure is shown;

[0048] Figure 3 A schematic diagram of a turbine straight blade obtained after a first coordinate transformation in an exemplary embodiment of the present disclosure is shown;

[0049] Figure 4 A schematic diagram of a blade profile mid-camber line in an exemplary embodiment of the present disclosure is shown;

[0050] Figure 5A schematic diagram showing an intersection point between a camber line normal line and a blade profile line in an exemplary embodiment of the present disclosure;

[0051] Figure 6 A schematic diagram of a storage file for adjusting geometric deformation parameters of turbine blades in an exemplary embodiment of the present disclosure is shown;

[0052] Figure 7 A schematic diagram of a NFFD control grid and a geometric model in an exemplary embodiment of the present disclosure is shown;

[0053] Figure 8 A schematic diagram showing the comparison between the geometry of a straight turbine blade obtained by using the method of the present application in an exemplary embodiment of the present disclosure and the geometry of a three-dimensional blade obtained after a second coordinate transformation and a prototype geometry is shown;

[0054] Fig. 9 A schematic diagram showing the control effect of a turbine blade on a secondary flow obtained by using the method of the present application in an exemplary embodiment of the present disclosure;

[0055] Fig.10 The following is a flowchart showing an execution of a parametric modeling system in an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION

[0056] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that the disclosure will be more comprehensive and complete and to fully convey the concepts of the example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0057] In addition, the accompanying drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and their repeated description will be omitted. Some of the block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and / or processor devices and / or microcontroller devices.

[0058] In this example implementation, a parametric modeling method for turbine blades based on blade end wall integrated design is first provided. The method can be applied to a terminal device, such as a mobile phone, a personal digital assistant, a laptop, a tablet computer, a smart watch, or other mobile terminal [flexibly adjusted according to specific circumstances, such as the terminal device is a server, etc.]. Figure 1 As shown in , the method may include the following steps:

[0059] Step S101: acquiring geometric data of a prototype blade, and performing coordinate transformation on the blade profile of the prototype turbine blade according to the geometric data and the rotation surface to obtain a plane straight blade;

[0060] Step S102: obtaining the median camber line of each radial cross-section of the straight blade according to the plane straight blade;

[0061] Step S103: determining the direction of the flow channel along each section according to the slope distribution of the mid-arc line of each radial section of the blade of the straight blade, and setting the number of flow channel sections to determine the segmentation trajectory of each section of the flow channel;

[0062] Step S104: extracting the coordinates of discrete points of each cross section of the flow channel according to the segmentation trajectory of each cross section of the flow channel, obtaining the control points of each cross section by combining the NURBS inverse algorithm, and forming a NFFD control grid according to the control points of each cross section;

[0063] Step S105: generating an initial shape of the turbine plane straight blade according to the NFFD control grid, and controlling grid deformation by using parameters of the NFFD control grid to modify the initial shape of the turbine plane straight blade to obtain a target shape of the turbine plane straight blade;

[0064] Step S106: coordinate transformation is performed on the target shape of the turbine plane straight blade to obtain the geometry of the turbine blade on the rotating surface.

[0065] Through the above-mentioned turbine blade parametric modeling method based on the integrated design of blade end wall, on the one hand, the coordinates of the discrete points of each section of the prototype blade are obtained by using the acquisition module as the input of the processing module, and then the NFFD control grid is obtained by the processing module through coordinate transformation, blade geometry analysis and blade flow channel segmentation. The NFFD grid deformation parameters control the coordinate changes of each control point of the grid, and the weight of the control point is changed to achieve the deformation and fine regulation of the turbine blade geometry. Finally, the output module outputs the final model that can be used for grid division. On the other hand, the NFFD grid is used to directly generate a complete three-dimensional turbine blade geometric surface, so that the high-order smooth transition between the blade and the end wall is easy to achieve. This method not only supports local modification of blade geometry, but also provides a wealth of geometric modification deformation parameters (including a large number of dimensionless parameters), which is convenient for determining the adjustment range of parameters to ensure that no unreasonable geometric shapes will appear. In the optimization design process, no additional constraints need to be set, thereby realizing a flexible and efficient optimization process. In addition, this method is suitable for the modeling and parameterization process of axial flow turbine blades for various purposes, and has a good control effect on the secondary flow in the end area.

[0066] Next, we will refer to Figures 1 to 9 Each step of the above method in this example implementation is described in more detail.

[0067] In step S101, the geometric data of the prototype blade is obtained, and the coordinate transformation of the turbine blade of the prototype blade is performed according to the geometric data and the rotation surface to obtain a plane straight blade.

[0068] For example, the geometric data of the prototype blade is obtained, and the (x, y, z) coordinates of the discrete points of the blade profile of each section of the prototype blade are converted into (r, θ, z) coordinates. Among them, x is the radial position of the blade profile, y is the circumferential position, and z is the axial position of the blade profile; when the rotating surface is a cylinder, r is the radius of the cylindrical coordinate system, and θ is the azimuth of the discrete point, with a value range of 0-2π. After the first coordinate transformation, the rotating turbine blade can be converted into a flat straight blade.

[0069] In one embodiment, a prototype blade is obtained (see Figure 2 ) geometric data, the (x, y, z) coordinates of the discrete points of each section of the prototype blade are converted into (r, θ, z) coordinates. Taking the cylindrical surface of revolution as an example, the coordinate transformation satisfies: θ = arctan(x / y). After the first coordinate transformation, the rotating turbine blade can be converted into a flat straight blade. Figure 3 .

[0070] In step S102 and step S103, the median arc line of each radial cross-section blade of the straight blade is obtained based on the plane straight blade; the direction of the flow channel along each cross-section is determined based on the slope distribution of the median arc line of each radial cross-section blade of the straight blade, and the number of flow channel sections is set to determine the cutting trajectory of each cross-section of the flow channel.

[0071] For example, the median arc line of each radial section of the straight blade is solved, and the direction of the flow channel along each section can be determined by the slope distribution of the median arc line. After setting the number of flow channel sections, the segmentation trajectory of each flow channel section is determined.

[0072] In one embodiment, the blade profile is divided into two parts, the suction side and the pressure side, according to the leading edge point and the trailing edge point, and the curvature distribution of the two parts is solved respectively, and the part with sudden curvature change is removed, that is, the pressure side and the suction side of the blade are retained.

[0073] The pressure side and suction side profiles of the blade are offset multiple times at equal intervals. Each offset generates 1-2 intersection points. These intersection points are arranged in axial order to form a point set. The profile formed by these point sets is the blade center arc line. See Figure 4 .in, Figure 4 (a) is the solution result of the mid-camber line of the blade tip and blade profile. Figure 4 (b) is the solution result of the camber line of the blade root and blade profile.

[0074] According to the given number of flow channel sections n, the middle arc is divided according to the uniform chord length method to obtain the dividing points, and then the normal direction of the middle arc at each dividing point is determined according to the slope distribution of the middle arc.

[0075] The intersection points of the normal line and the pressure side profile of the blade as well as the intersection points of the normal line and the suction side profile of the blade are solved respectively and arranged axially.

[0076] Connect the intersection points of the suction side and pressure side of each section of the blade radially in axial order, which is the segmentation trajectory of each section of the flow channel, see Figure 5 .in, Figure 5 (a) is the solution result of the blade tip and blade profile dividing point, Figure 5 (b) is the solution result of the blade root and blade profile dividing point.

[0077] In a specific embodiment, assuming that the middle arc is defined on the interval [a, b], the arc length is solved according to the integral formula in is the slope of the middle arc, and the middle arc is evenly divided into 10 segments, which means that the arc length of each segment is

[0078] To calculate the segmentation point, we need to ensure that the arc length of each segment is equal. Let i = 1, ... 10, and solve the equation Get the coordinates of the segmentation point.

[0079] At each cutting point, calculate the slope of the midline, i.e. the derivative The direction of the normal line can be determined by determining the slope of the median arc at each dividing point.

[0080] In step S104, the coordinates of discrete points of each flow channel section are extracted according to the segmentation trajectory of each flow channel section, the control points of each section are obtained in combination with the NURBS inverse algorithm, and the NFFD control grid is formed according to the control points of each section.

[0081] For example, the coordinates of discrete points of each flow channel section are extracted from the segmentation trajectory of each flow channel section, and the control points of each section can be obtained from the coordinates of the discrete points through the NURBS inverse algorithm. These control points constitute the preliminary NFFD control grid.

[0082] More specifically, node vectors are determined according to the coordinates of discrete points of each cross section of the flow channel, and the node vectors are used to construct non-uniform B-spline basis functions.

[0083] The coefficient matrix and control point inverse equation group are established to obtain the control vertices of each section curve.

[0084] The control points of each section are arranged along the blade flow direction to form a closed NFFD control grid.

[0085] In one embodiment, according to the coordinates q of the discrete points of each cross section of the flow channel i,j To determine the node vector U, use the node vector to construct the non-uniform B-spline basis function:

[0086]

[0087] Establish the coefficient matrix and control point inverse equation group to obtain the control vertices of each section curve:

[0088]

[0089] Among them, d i,j For the control point.

[0090] The control points of each section are arranged along the blade flow direction to form a closed NFFD control grid.

[0091] In step S105, the initial shape of the turbine plane straight blade is generated according to the NFFD control grid, and the grid deformation is controlled by using the parameters of the NFFD control grid to modify the initial shape of the turbine plane straight blade to obtain the target shape of the turbine plane straight blade.

[0092] For example, the coordinate changes of each control point of the grid are controlled according to the NFFD grid deformation parameters. When the control point is moved, the NFFD algorithm will recalculate the coordinates of the shape value points of the turbine blade geometry according to the new position of the control point.

[0093] Add weights to local control points to modify turbine blade details.

[0094] In one embodiment, according to the NFFD mesh deformation parameters (see Figure 6 ) controls the coordinate changes of each control point of the grid. When the control point is moved, the NFFD algorithm recalculates the coordinates of the value points of the turbine blade geometry according to the new position of the control point:

[0095]

[0096] Where P is the (r, θ, z) rectangular coordinate vector of a point on the straight blade geometric model.

[0097] Add weight W to the local control point i,j,k , modify the turbine blade details, see Figure 7 .in, Figure 7 (a) and (b) are schematic diagrams of blade shapes from two different perspectives.

[0098] In step S106, coordinate transformation is performed on the target shape of the turbine plane straight blade to obtain the geometry of the turbine blade on the rotating surface.

[0099] For example, the straight turbine blade obtained in step S105 is subjected to a second coordinate transformation to obtain the geometry of the turbine blade on the rotating surface, which is taken as the final result.

[0100] In one embodiment, the (r, θ, z) coordinates of the discrete points of the blade profile of each cross section of the straight blade are converted to (x, y, z) coordinates. Taking the cylindrical surface of revolution as an example, the coordinate transformation satisfies: x = rsinθ, y = rcosθ. The final result can be obtained after the second coordinate transformation. Figure 8 .in, Figure 8 (a) is the comparison between the rotating surface blade modeling result and the prototype blade. Figure 8 (b) is the comparison between the flat straight blade modeling result and the prototype blade.

[0101] like Fig. 9 The figure shows the control effect of turbine blades on secondary flow obtained by the parametric modeling method of turbine blades based on the integrated design of blade end wall. Fig. 9 (a) is the axial vorticity distribution cloud diagram of the prototype blade. Fig. 9 (b) is a cloud diagram of the axial vorticity distribution of the blade obtained by the present invention.

[0102] It should be noted that, although the steps of the method in the present disclosure are described in a specific order in the accompanying drawings, this does not require or imply that the steps must be performed in this specific order, or that all the steps shown must be performed to achieve the desired results. Additionally or alternatively, some steps may be omitted, multiple steps may be combined into one step for execution, and / or one step may be decomposed into multiple steps for execution, etc. In addition, it is also easy to understand that these steps may be, for example, executed synchronously or asynchronously in multiple modules / processes / threads.

[0103] Furthermore, in this example embodiment, a turbine blade parametric modeling system based on blade end wall integrated design is also provided. The turbine blade parametric modeling system based on blade end wall integrated design may include a first blade coordinate conversion module, a blade geometry analysis module, a blade flow channel segmentation module, a NFFD control grid generation module, a shape modification module, and a second blade coordinate conversion module. Among them:

[0104] The first blade coordinate conversion module is used to obtain geometric data of the prototype blade, and to perform coordinate transformation on the turbine blade of the prototype blade according to the geometric data and the rotation surface to obtain a plane straight blade;

[0105] The blade geometry analysis module is used to obtain the median arc line of each radial section of the straight blade according to the plane straight blade;

[0106] The blade flow channel segmentation module is used to determine the direction of the flow channel along each section according to the slope distribution of the mid-arc line of each radial section of the blade of the straight blade, and set the number of flow channel sections to determine the segmentation trajectory of each section of the flow channel;

[0107] NFFD control grid generation module, used to extract the coordinates of discrete points of each section of the flow channel according to the segmentation trajectory of each flow channel section, obtain the control points of each section in combination with the NURBS inverse algorithm, and form the NFFD control grid according to the control points of each section;

[0108] A shape modification module is used to generate an initial shape of the turbine plane straight blade according to the NFFD control grid, and to control grid deformation by using parameters of the NFFD control grid to modify the initial shape of the turbine plane straight blade to obtain a target shape of the turbine plane straight blade;

[0109] The second blade coordinate conversion module is used to perform coordinate transformation on the target shape of the turbine plane straight blade to obtain the geometry of the turbine blade on the rotating surface.

[0110] Specifically, Fig.10 The figure shows a specific flow chart of the turbine blade parametric modeling system based on blade end wall integrated design. The input module is the first blade coordinate conversion module; the processing module is the blade geometry analysis module, the blade flow channel segmentation module, the NFFD control grid generation module and the shape modification module; the output module is the second blade coordinate conversion module.

[0111] Through the above-mentioned turbine blade parametric modeling method and system based on the integrated design of blade end wall, on the one hand, the coordinates of the discrete points of each section of the prototype blade are obtained by using the acquisition module as the input of the processing module, and then the NFFD control grid is obtained by the processing module through coordinate transformation, blade geometry analysis and blade flow channel segmentation. The NFFD grid deformation parameters control the coordinate changes of each control point of the grid, and the weight of the control point is changed to achieve the deformation and fine regulation of the turbine blade geometry. Finally, the output module outputs the final model that can be used for grid division. On the other hand, the NFFD grid is used to directly generate a complete three-dimensional turbine blade geometric surface, so that the high-order smooth transition between the blade and the end wall is easy to achieve. This method not only supports local modification of blade geometry, but also provides a wealth of geometric modification deformation parameters (including a large number of dimensionless parameters), which is convenient for determining the adjustment range of parameters to ensure that no unreasonable geometric shapes will appear. In the optimization design process, no additional constraints need to be set, thereby realizing a flexible and efficient optimization process. In addition, this method is suitable for the modeling and parameterization process of axial flow turbine blades for various purposes, and has a good control effect on the secondary flow in the end area.

[0112] Regarding the device in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0113] It should be noted that although several modules or units of the device for action execution are mentioned in the above detailed description, this division is not mandatory. In fact, according to the embodiment of the present disclosure, the features and functions of two or more modules or units described above can be concretized in one module or unit. Conversely, the features and functions of a module or unit described above can be further divided into multiple modules or units for concretization. The components displayed as modules or units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the disclosed solution. Those of ordinary skill in the art can understand and implement it without paying creative work.

[0114] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. This application is intended to cover any modification, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary techniques in the art that are not disclosed in the present disclosure. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present disclosure are indicated by the appended claims.

Claims

1. A parametric modeling method for turbine blades based on blade end wall integrated design, characterized in that: The method includes: The geometric data of the prototype blade is obtained, and the blade profile of the prototype turbine blade is transformed into a coordinate according to the geometric data and the rotation surface to obtain a plane straight blade; According to the plane straight blade, the median arc line of each radial cross-section of the straight blade is obtained; The direction of the flow channel along each section is determined according to the slope distribution of the mid-arc line of each radial section of the blade of the straight blade, and the number of flow channel sections is set to determine the segmentation trajectory of each section of the flow channel; The coordinates of the discrete points of each section of the flow channel are extracted according to the segmentation trajectory of each section of the flow channel, and the control points of each section are obtained by combining the NURBS inverse algorithm, and the NFFD control grid is formed according to the control points of each section; The initial shape of the turbine plane straight blade is generated according to the NFFD control grid, and the grid deformation is controlled by using the parameters of the NFFD control grid to modify the initial shape of the turbine plane straight blade to obtain the target shape of the turbine plane straight blade; The target shape of the turbine plane straight blade is transformed into coordinates to obtain the geometry of the turbine blade on the rotating surface.

2. The parametric modeling method for turbine blades based on blade end wall integrated design according to claim 1 is characterized in that: The steps of obtaining geometric data of the prototype blade and performing coordinate transformation on the blade profile of the prototype turbine blade according to the geometric data and the rotation surface to obtain a planar straight blade include: Obtain the geometric data of the prototype blade, determine the rotation surface, and convert the (x, y, z) coordinates of the discrete points of each cross-sectional blade of the prototype blade into (r, θ, z) coordinates; Among them, x is the radial position of the blade, y is the circumferential position, and z is the axial position of the blade.

3. The parametric modeling method for turbine blades based on blade end wall integrated design according to claim 1 is characterized in that: The step of obtaining the median camber line of each radial cross-section blade of the straight blade according to the plane straight blade comprises: The blade profile is divided into the suction side and the pressure side according to the leading edge point and the trailing edge point, and the curvature distribution of the suction side and the pressure side is calculated respectively, and the sudden change of curvature is removed to obtain the pressure side and the suction side of the blade body; The pressure side profile and suction side profile of the blade body are offset equidistantly for multiple times, and a number of intersection points are generated after each offset. The intersection points are arranged in axial order to form a point set to form the median arc line of each radial section of the straight blade.

4. The parametric modeling method for turbine blades based on blade end wall integrated design according to claim 1 is characterized in that: The step of determining the direction of the flow channel along each section according to the slope distribution of the mid-arc line of each radial section of the blade of the straight blade, and setting the number of flow channel sections to determine the segmentation trajectory of each section of the flow channel includes: According to the preset number of flow channel sections n, the middle arc is divided according to the uniform chord length method to obtain the dividing points; Determine the normal direction of the middle arc at each cutting point according to the distribution of the slope of the middle arc; Solve the intersection points of the normal line and the pressure side profile of the blade, and the normal line and the suction side profile of the blade respectively, and arrange them axially; The suction side and pressure side of each section of the blade are radially connected in axial order through the intersection of the normal line and the pressure side profile of the blade body and the normal line and the suction side profile of the blade body to obtain the cutting trajectory of each section of the flow channel.

5. The turbine blade parameterized modeling method based on blade end wall integrated design according to claim 1 is characterized in that: The steps of extracting the coordinates of discrete points of each section of the flow channel according to the segmentation trajectory of each flow channel section, obtaining the control points of each section by combining the NURBS inverse algorithm, and forming the NFFD control grid according to the control points of each section include: Extracting the coordinates of discrete points of each cross section of the flow channel according to the segmentation trajectory of each cross section of the flow channel; Determine the node vector according to the coordinates of the discrete points of each cross section of the flow channel; Construct non-uniform B-spline basis functions based on knot vectors; Based on non-uniform B-spline basis functions and combined with NURBS inverse algorithm, the coefficient matrix and control point inverse equations are established to obtain the control vertices of each cross-sectional curve. The control vertices of each cross-sectional curve are arranged along the blade flow direction to form a closed NFFD control grid.

6. The turbine blade parameterized modeling method based on blade end wall integrated design according to claim 1 is characterized in that: The steps of generating an initial shape of a turbine plane straight blade according to a NFFD control grid, controlling grid deformation by using parameters of the NFFD control grid, and modifying the initial shape of the turbine plane straight blade to obtain a target shape of the turbine plane straight blade include: Generate the initial shape of the turbine plane straight blade based on the NFFD control grid; When the control point is moved, the NFFD algorithm recalculates the coordinates of the shape value points of the turbine blade geometry according to the new positions of the control vertices of each cross-sectional curve; By adding weights to local control points, the turbine blade details are modified to obtain the target shape of a turbine flat straight blade.

7. A parametric modeling system for turbine blades based on blade end wall integrated design, characterized in that: The system includes: The first blade coordinate conversion module is used to obtain geometric data of the prototype blade, and to perform coordinate transformation on the turbine blade of the prototype blade according to the geometric data and the rotation surface to obtain a plane straight blade; The blade geometry analysis module is used to obtain the median arc line of each radial section of the straight blade according to the plane straight blade; The blade flow channel segmentation module is used to determine the direction of the flow channel along each section according to the slope distribution of the mid-arc line of each radial section of the blade of the straight blade, and set the number of flow channel sections to determine the segmentation trajectory of each section of the flow channel; NFFD control grid generation module, used to extract the coordinates of discrete points of each section of the flow channel according to the segmentation trajectory of each flow channel section, obtain the control points of each section in combination with the NURBS inverse algorithm, and form the NFFD control grid according to the control points of each section; A shape modification module is used to generate an initial shape of the turbine plane straight blade according to the NFFD control grid, and to control grid deformation by using parameters of the NFFD control grid to modify the initial shape of the turbine plane straight blade to obtain a target shape of the turbine plane straight blade; The second blade coordinate conversion module is used to perform coordinate transformation on the target shape of the turbine plane straight blade to obtain the geometry of the turbine blade on the rotating surface.

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