Turbine blade profile optimization method, blade, computer equipment and storage medium

Abstract

The invention relates to a turbine blade profile optimization method, a blade, computer equipment and a storage medium. The method comprises the following steps: determining a mean camber line coordinate of an initial blade profile; determining a tangent angle of each point of an arc coordinate in the initial blade profile and a corresponding coordinate, and performing nondimensionalization on the tangent angle and the corresponding coordinate; deriving the dimensionless coordinates and the angle to obtain a mean camber line dimensionless angle slope; applying the calculated mean camber line dimensionless angle slope to a disturbance function to obtain a disturbed dimensionless angle slope; carrying out integration on the calculated post-disturbance dimensionless angle slope to obtain post-disturbance dimensionless angle distribution, and carrying out normalization by using a trailing edge dimensionless angle to enable the trailing edge dimensionless angle theta 'to be equal to 1; carrying out inverse operation on the disturbed dimensionless angle and the coordinates to obtain actual mean camber line angle distribution, and carrying out integration to obtain disturbed mean camber line coordinates; and determining a newly constructed mean camber line, and generating a reconstructed blade profile according to original blade parameters and a modeling method.

Description

Technical Field

[0001] The present invention relates to the technical field of impeller blade design, and in particular to an impeller blade profile optimization method, blades, computer equipment and storage medium, which can be applied to impeller structures in aircraft engines such as fans and compressors. Background Art

[0002] Fans, compressors and other impellers are important components of aircraft engines, and blade aerodynamic optimization design is of great significance to improving the aerodynamic performance of aircraft engines. However, the internal flow conditions of aircraft engines are very complex, with complex flow characteristics such as multi-stage and unsteady; at the same time, the aerodynamic design of blades is mutually restricted by design characteristics such as noise and structure, which makes the design process of aircraft engine impeller components such as fans and compressors particularly complex, facing problems such as multi-stage matching and multi-disciplinary coupling.

[0003] Traditional fan and compressor aerodynamic design is based on experimental or numerical simulation technology, and needs to be repeatedly iterated through design-evaluation-redesign. When faced with multi-objective and multi-disciplinary optimization problems, repeated iterations are extremely costly and cannot meet the high-performance requirements of aerodynamic design of new-generation aircraft engines. As the basic unit of impeller blade shaping, two-dimensional blade design has a crucial impact on the performance of the impeller. Existing two-dimensional blade designs of impellers mostly adopt the idea of ​​superimposed thickness of the mid-arc line, which has a strong dependence on experience. In engineering applications, it is necessary to combine experimental or numerical results to adjust the blade design parameters for repeated iterative optimization, which requires a lot of experiments and calculations, and is time-consuming.

[0004] Aiming at the high aerodynamic performance and multidisciplinary joint design requirements of the aerodynamic design of the new generation of aircraft engines, the use of fast and accurate optimization algorithms can achieve efficient design of high-performance impeller two-dimensional blades. Whether using traditional optimization algorithms or optimization algorithms based on artificial intelligence, it is necessary to construct a sample database of blade profiles and aerodynamic, noise, structural and other characteristics, and to perturb the parameters of blade modeling and reconstruct the blade profile to form a sample space. Modern fan and compressor blades all use controllable diffusion blades. Unlike traditional blades, the curvature of the mid-arc of the controllable diffusion blade cannot be characterized by a few parameters, but is a free curve formed by optimizing the flow field characteristics, so that the fluid flows and expands according to the designer's intention to achieve the best performance of fluid machinery. The mid-arc of the controllable diffusion blade needs to be described by coordinates or metal angles from the leading edge to the trailing edge. However, in the optimization design, direct perturbation of the mid-arc coordinates or angles will bring about the problem of too many parameters and too large a sample size requirement; at the same time, direct perturbation has the problem of too high freedom, which makes it difficult to ensure the rationality of the mid-arc after perturbation, which is easy to cause sample failure and waste optimization resources.

[0005] The present invention is proposed based on the above research background, and aims to provide a method for optimizing the blade profile of a turbine, which can ensure the rationality of the blade geometry and improve the efficiency of blade profile optimization while reducing the disturbance variables. Summary of the invention

[0006] In order to solve the following technical problems existing in the process of optimizing the controllable diffusion blade shape of impellers such as fans and compressors: (1) there is a problem of too many variables in the reconstruction of the mid-arc line, which will lead to a large number of samples required and reduce the optimization efficiency; (2) there is a problem of too high freedom in the direct perturbation of the mid-arc line modeling parameters, which will lead to a large number of geometric unreasonable situations in the reconstructed blade shape, causing sample failure and waste of optimization resources; (3) the mid-arc line parameters of different blades, different blade heights and different axial positions have different variable ranges, making it difficult to determine a reasonable perturbation range; the purpose of the present invention is to provide a method for optimizing the blade shape of an impeller, which has the advantages of reasonable design, reducing the number of perturbation parameters and the number of samples required, improving sample utilization efficiency and improving blade performance.

[0007] In order to achieve the above object, the present invention provides a method for optimizing the blade profile of an impeller, the method comprising the following steps: Step 1: Obtain the initial blade profile of the impeller and determine the mid-arc coordinates of the initial blade profile (x i ,y i ), the above-mentioned initial blade profile includes a controllable diffusion blade profile; Step 2: Determine the tangent angle θ of each point on the initial blade mid-arc coordinate according to the initial blade mid-arc i And the corresponding coordinates (x i ,y i ), and non-dimensionalize it to obtain the dimensionless coordinate X and dimensionless angle Θ, where x i、 y i are the axial coordinates of the mid-arc line on the X-axis and the ordinate on the Y-axis respectively; i is the serial number of the point on the mid-arc line of the initial blade profile; when i=1, it represents the serial number of the leading edge position point of the initial blade profile; when i=2, it represents the serial number of the trailing edge position point of the initial blade profile; when i is any other value, it represents the serial number of any position point on the mid-arc line except the leading edge and trailing edge positions; Step 3: Derivative the dimensionless coordinate X and dimensionless angle θ obtained in step 2 to obtain the dimensionless angle slope of the mid-arc , the dimensionless angle slope k characterizes the second derivative of the mid-arc coordinate; Step 4: Construct a disturbance function according to the turbine flow field requirements , apply the dimensionless angle slope of the mid-arc calculated in step 3 to the above perturbation function to obtain the dimensionless angle slope after perturbation ; Step 5: Integrate the dimensionless angle slope after disturbance calculated in step 4. The integral formula is: , and obtain the dimensionless angular distribution after disturbance (X ’ ,Θ ’ ), where X ’ is the dimensionless coordinate after perturbation, Θ ’ is the dimensionless angle after disturbance, and is normalized using the dimensionless angle of the trailing edge to make the dimensionless angle of the trailing edge θ ’= 1; Step 6: The dimensionless angle and coordinates obtained in step 5 are reversed according to the method in step 2 to obtain the actual mid-arc angle distribution ( x',θ' ), and integrate to obtain the coordinates of the mid-arc after disturbance ( x i ’ , y i ’ ), the above integral formula is ; Step 7: Determine the newly constructed mid-arc line according to the coordinates of the mid-arc line after disturbance calculated in step 6, and generate the reconstructed blade shape according to the original blade parameters and modeling method.

[0008] As a further optimization of the above solution, the calculation formula of the tangent angle θ in step 2 is as follows: ; The dimensionless angle θ characterizes the first derivative of the mid-arc coordinate; the dimensionless angle θ i and the dimensionless coordinate X i The calculation formula is as follows: X i =( x i - x 1) / ( x 2- x 1), Θ i =( θ i - θ 1) / ( θ 2- θ 1), where x1, x2, x i The meaning is the same as before; θ 1 is the tangent angle of the leading edge of the initial blade, θ 2 is the tangent angle of the trailing edge of the initial blade profile, θ i It is the tangent angle of any point on the mid-camber line except the leading edge and trailing edge.

[0009] As a further optimization of the above solution, the linear shape of the reconstructed blade profile is smooth and has no inflection point.

[0010] Another aspect of the present invention provides an impeller blade. The impeller blade is obtained by the impeller blade profile optimization method described above, and the blade surface is smooth.

[0011] As a further optimization of the above solution, the impeller blades are fan blades or compressor blades of an aircraft engine.

[0012] Another aspect of the present invention provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the impeller blade profile optimization method when executing the computer program.

[0013] Finally, the present invention also proposes a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the impeller blade profile optimization method are implemented.

[0014] The impeller blade optimization method of the present invention has the following beneficial effects: 1. By performing high-order perturbations on the initial blade mid-arc line, the continuity of the mid-arc line can be ensured, and the appearance of unreasonable geometry such as blade recurve can be avoided. This not only unifies the mid-arc line parameters of different blades, different blade heights, and different axial positions, making it easier to determine a unified range of perturbations, but also reduces the number of perturbation parameters and sample requirements, improves sample utilization efficiency, and ultimately achieves the goal of improving optimization efficiency. 2. Since the airflow in the blade channel realizes pressure expansion and work through the airflow turning, the slope of the arc angle in the blade represents the turning angle of the blade at this position, and also represents the load intensity at this position. The disturbance amount in the present invention is directly reflected as the load position of the controllable diffusion blade, and has a clear correlation with the optimization methods such as adjusting the shock wave position and reducing the flow separation on the suction surface; 3. The controllable diffusion blade profile obtained through high-order optimization of the blade mid-arc can control the velocity distribution on the blade surface, suppress the shock wave intensity, and improve the blade performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0016] Figure 1 It is a schematic diagram of the initial blade profile of the impeller, where the dotted line is the center arc line of the blade profile.

[0017] Figure 2For the definition of angles and coordinates, the coordinates of the leading edge point of the mid-arc are (x1, y1), the angle between the tangent and the axis is θ1, the coordinates of the trailing edge are (x2, y2), the angle between the tangent and the axis is θ2, and the coordinates of any position in the middle are (x, y) and the tangent angle is θ.

[0018] Figure 3 is the distribution of dimensionless angles with respect to dimensionless coordinates, the solid line is the initial distribution, and the dotted line is the distribution after disturbance.

[0019] Figure 4 is the distribution of the dimensionless angle slope with respect to the dimensionless coordinate, the solid line is the initial distribution, and the dotted line is the distribution after disturbance.

[0020] Figure 5 is the distribution of the perturbation applied to the dimensionless angular slope.

[0021] Figure 6 The schematic diagram of the reconstructed blade shape after the disturbance is applied, where the dotted line is the center arc line of the blade shape. The blade curvature changes significantly where the disturbance is strong, but the blade itself still maintains a reasonable blade shape.

[0022] Figure 7 It is a comparison diagram between the initial blade shape and the reconstructed blade shape. The solid line is the initial blade shape, and the dotted line is the reconstructed blade shape.

[0023] Figure 8 The figure is a flow chart corresponding to the method of the present invention.

[0024] Fig. 9 It is the Mach number cloud diagram of the initial blade flow field.

[0025] Fig.10 Mach number cloud diagram for optimizing blade flow field.

[0026] Fig.11 Comparison of isentropic Mach number distribution on blade surface before and after optimization. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0028] Combine the following Figure 1-Figure 11 The impeller blade profile optimization method of the present invention is described in detail.

[0029] The present invention proposes a method for optimizing the blade profile of an impeller, the method comprising the following steps: Step 1: Obtain the initial blade profile of the impeller and determine the mid-arc coordinates of the initial blade profile (x i ,y i ), the above-mentioned initial blade profile includes a controllable diffusion blade profile; Step 2: Determine the tangent angle θ of each point on the initial blade mid-arc coordinate according to the initial blade mid-arc i And the corresponding coordinates (x i ,y i ), and non-dimensionalize it to obtain the dimensionless coordinate X and dimensionless angle Θ, where x i、 y i are the axial coordinates of the mid-arc line on the X-axis and the ordinate on the Y-axis respectively; i is the serial number of the point on the mid-arc line of the initial blade profile; when i=1, it represents the serial number of the leading edge position point of the initial blade profile; when i=2, it represents the serial number of the trailing edge position point of the initial blade profile; when i is any other value, it represents the serial number of any position point on the mid-arc line except the leading edge and trailing edge positions; Step 3: Derivative the dimensionless coordinate X and dimensionless angle θ obtained in step 2 to obtain the dimensionless angle slope of the mid-arc , the dimensionless angle slope k characterizes the second derivative of the mid-arc coordinate; Step 4: Construct a disturbance function according to the turbine flow field requirements , apply the dimensionless angle slope of the mid-arc calculated in step 3 to the above perturbation function to obtain the dimensionless angle slope after perturbation ; Step 5: Integrate the dimensionless angle slope after disturbance calculated in step 4. The integral formula is: , and obtain the dimensionless angular distribution after disturbance (X ’ ,Θ ’ ), where X ’ is the dimensionless coordinate after perturbation, Θ ’ is the dimensionless angle after disturbance, and is normalized using the dimensionless angle of the trailing edge to make the dimensionless angle of the trailing edge θ ’= 1; Step 6: The dimensionless angle and coordinates obtained in step 5 are reversed according to the method in step 2 to obtain the actual mid-arc angle distribution ( x',θ' ), and integrate to obtain the coordinates of the mid-arc after disturbance ( x i ’,y i ’ ), the above integral formula is ; Step 7: Determine the newly constructed mid-arc line according to the coordinates of the mid-arc line after disturbance calculated in step 6, and generate the reconstructed blade shape according to the original blade parameters and modeling method.

[0030] The calculation formula of the tangent angle θ in step 2 is as follows: ; The dimensionless angle θ characterizes the first derivative of the mid-arc coordinate; the dimensionless angle θ i and the dimensionless coordinate X i The calculation formula is as follows: X i =( x i - x 1) / ( x 2- x 1), Θ i =( θ i - θ 1) / ( θ 2- θ 1), where x1, x2, x i The meaning is the same as before; θ 1 is the tangent angle of the leading edge of the initial blade, θ 2 is the tangent angle of the trailing edge of the initial blade profile, θ i It is the tangent angle of any point on the mid-camber line except the leading edge and trailing edge.

[0031] Furthermore, the linear shape of the reconstructed blade profile is smooth and has no inflection points.

[0032] In yet another embodiment of the present invention, there is provided an impeller blade. The impeller blade is obtained by the aforementioned impeller blade profile optimization method, and the blade surface is smooth.

[0033] Exemplarily, the impeller blade may be a fan blade or a compressor blade of an aircraft engine.

[0034] In yet another embodiment of the present invention, a computer device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the impeller blade profile optimization method when executing the computer program.

[0035] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, and is specifically suitable for loading and executing one or more instructions in a computer storage medium to implement a corresponding method flow or a corresponding function; In yet another embodiment of the present invention, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the impeller blade profile optimization method are implemented.

[0036] It is understandable that the computer-readable storage medium here can include both the built-in storage medium in the computer device and the extended storage medium supported by the computer device. The computer-readable storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space, and these instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory.

[0037] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The present invention is described with reference to flowcharts and / or block diagrams of methods, devices, and computer program products according to embodiments of the present invention. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of processes and / or boxes in the flowchart and / or block diagram, may be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that instructions executed by the processor of a computer or other programmable data processing device generate instructions for implementing the instructions in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be stored in a computer-readable memory that can guide a computer or other programmable data processing device to work in a specific way, so that the instructions stored in the computer-readable memory produce a product including an instruction device, which implements the functions specified in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide for implementing the process in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0038] It should be noted that the reason why the coordinates are calculated only using x is that the blades of the impeller are generally represented by axial position or chord length direction. The axial direction is the x direction, and the axial coordinate is the x coordinate of a point on the mid-arc line. The chord length direction is the direction of the line connecting the leading and trailing edge points (chord line). The chord-wise coordinate is the coordinate of the projection point of the point on the chord line from the leading edge point. Since the axial coordinate and the longitudinal coordinate are in equal proportion, the dimensionless coordinates obtained when dimensionlessization is performed are equal, so a relatively simple expression is used here.

[0039] A comparative example is used below for comparison with the blade profile optimization method of the present invention.

[0040] Select an unoptimized aero-engine fan blade root blade shape and operate it in a high subsonic flow environment. Fig. 9 As shown, it shows that high Mach number areas appear near the leading edge of the pressure surface and in the middle of the suction surface, and there are large shock wave losses.

[0041] The above optimization method of the present invention is used to modify the blade mid-camber line and optimize iteratively, and finally the following is obtained: Fig.10 The blade profile and flow field shown are shown in Fig.11 It is not difficult to find that the pressure surface of the blade of the present invention is close to the leading edge position and the suction surface is in the middle of the blade, and the high Mach number is suppressed, thereby improving the flow field and blade performance.

[0042] The above description of the embodiments is to facilitate the understanding and application of the present invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the embodiments herein, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A method for optimizing the blade profile of a turbine, characterized in that: The steps include: Step 1: Obtain the initial blade profile of the impeller and determine the mid-arc coordinates of the initial blade profile (x i ,y i ), the above-mentioned initial blade profile includes a controllable diffusion blade profile; Step 2: Determine the tangent angle θ of each point on the initial blade mid-arc coordinate according to the initial blade mid-arc i And the corresponding coordinates (x i ,y i ), and non-dimensionalize it to obtain the dimensionless coordinate X and dimensionless angle Θ, where x i、 y i are the axial coordinates of the mid-arc line on the X-axis and the ordinate on the Y-axis, respectively; i is the serial number of the point on the mid-arc line of the initial blade profile; when i=1, it represents the serial number of the leading edge position point of the initial blade profile; when i=2, it represents the serial number of the trailing edge position point of the initial blade profile; when i is any other value, it represents the serial number of any position point on the mid-arc line except the leading edge and trailing edge positions; Step 3: Derivative the dimensionless coordinate X and dimensionless angle θ obtained in step 2 to obtain the dimensionless angle slope of the mid-arc , the dimensionless angle slope k characterizes the second derivative of the mid-arc coordinate; Step 4: Construct a disturbance function according to the turbine flow field requirements , apply the dimensionless angle slope of the mid-arc calculated in step 3 to the above perturbation function to obtain the dimensionless angle slope after perturbation ; Step 5: Integrate the dimensionless angle slope after disturbance calculated in step 4. The integral formula is: , and obtain the dimensionless angular distribution after disturbance (X ’ ,Θ ’ ), where X ’ is the dimensionless coordinate after perturbation, Θ ’ is the dimensionless angle after disturbance, and is normalized using the dimensionless angle of the trailing edge to make the dimensionless angle of the trailing edge θ ’= 1; Step 6: The dimensionless angle and coordinates obtained in step 5 are reversed according to the method in step 2 to obtain the actual mid-arc angle distribution ( x ', θ '), and integrate to obtain the coordinates of the mid-arc after disturbance ( x i ', y i '), the above integral formula is ; Step 7: Determine the newly constructed mid-arc line according to the coordinates of the mid-arc line after disturbance calculated in step 6, and generate the reconstructed blade shape according to the original blade parameters and modeling method.

2. The impeller blade optimization method according to claim 1, characterized in that: The tangent angle in step 2 The calculation formula is as follows: ； The dimensionless angle θ characterizes the first derivative of the mid-arc coordinate; the dimensionless angle θ i and the dimensionless coordinate X i The calculation formula is as follows: X i =( x i - x 1) / ( x 2- x 1), Θ i =( θ i - θ 1) / ( θ 2- θ 1), where x1, x2, x i The meaning is the same as before; θ 1 is the tangent angle of the leading edge of the initial blade, θ 2 is the tangent angle of the trailing edge of the initial blade profile, θ i It is the tangent angle of any point on the mid-camber line except the leading edge and trailing edge.

3. The impeller blade optimization method according to claim 1, characterized in that: The linear shape of the reconstructed blade profile is smooth and has no inflection point.

4. An impeller blade, characterized in that: The impeller blade is obtained by the method according to any one of claims 1 to 3, and the surface of the blade is smooth.

5. The impeller blade according to claim 4, characterized in that: The impeller blades are fan blades or compressor blades of an aircraft engine.

6. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the impeller blade profile optimization method according to any one of claims 1 to 3 are implemented.

7. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the impeller blade profile optimization method according to any one of claims 1 to 3 are implemented.

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