Parameterized propeller modeling method based on shell unit

Abstract

The invention discloses a parameterized propeller modeling method based on a shell unit. The parameterized propeller modeling method is used for optimizing the design of a propulsion system of an aircraft. According to the method, geometric parameters and design conditions of a propeller are determined according to a design task book and working conditions; then, based on aerodynamic load distribution, chord length changes of the blades are calculated, and the torsion rule of the blades is determined according to the inflow angle and the attack angle; furthermore, a proper NACA airfoil profile is selected, and a three-dimensional geometric section of the blade is generated, so that excellent aerodynamic performance is ensured. On the basis, the connection relation between the nodes and the units of the blades is established through grid division, and a shell unit finite element grid is formed. Constructing a shell unit model by adopting an isoparametric element theory, and calculating a stiffness matrix and a mass matrix of the blade; and finally, in combination with material parameters and boundary conditions, establishing a kinetic equation, and performing modal and dynamic response analysis. According to the method, the blade design and analysis efficiency is effectively improved, the structural strength and the vibration characteristic are guaranteed, and a novel propelling solution with economical efficiency and innovativeness is provided for Boeing aircrafts and other types of aircrafts.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aerospace engineering, and particularly relates to a parameterized propeller modeling method based on shell elements. BACKGROUND

[0002] Propeller propulsion is a traditional and efficient propulsion method in the field of aviation. Since the Wright brothers successfully flew for the first time in 1903, propeller propulsion systems and aircraft design have been continuously improved. The economy of the aviation propulsion device is an important indicator of its technical level and practicability, which is usually measured by propulsion efficiency. Propulsion efficiency is the ratio of the propulsion power delivered by the aircraft engine to the power consumed by itself. Higher propulsion efficiency can significantly reduce fuel consumption and extend flight range. Increasing the bypass ratio helps to reduce jet energy loss and improve propulsion efficiency. Among all the mainstream aviation propulsion methods, the equivalent bypass ratio of the propeller is the largest, reaching 50-100, and the propulsion efficiency in the typical working range can exceed 0.8. Especially in the regional passenger aircraft, the propeller can reduce the specific fuel consumption by about 40% compared with the turbofan engine. Therefore, under appropriate working conditions, the propeller propulsion shows excellent economy and provides good take-off and landing capability.

[0003] Designing an efficient propeller is one of the main goals to improve the flight time and efficiency of an aircraft. To ensure that the propeller meets the airworthiness requirements and works reliably, its aerodynamic and dynamic characteristics must be analyzed in depth. Currently, the mainstream analysis method is to construct a three-dimensional model based on parameters such as flight speed, propeller speed, pull, diameter, number of blades, and airfoil, and then perform aerodynamic performance and dynamic characteristic analysis in finite element analysis software to predict the performance of the propeller under specific working conditions.

[0004] After setting the parameters of the propeller in the prior art, a three-dimensional model still needs to be manually established in a three-dimensional software, and then imported into a finite element software for analysis. In addition, the finite element model established in the finite element software generally uses hexahedral elements, which requires high computing performance and slow calculation speed. SUMMARY

[0005] The application aims to provide a parameterized propeller modeling method based on shell elements, which can automatically establish a blade shell element finite element model after setting the parameters.

[0006] To solve the technical problems, the technical scheme of the application is as follows:

[0007] A parameterized propeller modeling method based on shell elements, the parameterized propeller modeling method comprising:

[0008] According to the design task and working condition of the aircraft, the geometric parameters and design conditions of the propeller are determined;

[0009] Based on the geometric parameters, the chord length distribution of the blade along the radial direction is calculated;

[0010] According to the design condition and the chord length distribution, the inflow angle and the angle of attack are calculated, and the installation angle distribution of the blade along the radial direction is determined;

[0011] According to the chord length distribution and the installation angle distribution, the airfoil is selected and the blade section coordinates are established, and the three-dimensional geometric model of the blade is generated;

[0012] Based on the three-dimensional geometric model, the mesh is divided, the node coordinates and element connection relationship of the blade are established, and the shell element finite element grid is formed; Based on the isoparametric element theory, the shell element model is established, and the stiffness matrix and mass matrix of the blade are calculated;

[0013] The stiffness matrix and mass matrix are used to establish the dynamic equation, and the modal and dynamic response analysis are carried out, and the dynamic characteristics of the blade are obtained.

[0014] Further, based on the geometric parameters, according to the aerodynamic load distribution law and the demand of propulsive efficiency, the chord length change of the blade along the radial direction is calculated, and the chord length distribution curve of the blade is obtained.

[0015] Further, the design condition and the chord length distribution are input, the inflow angle and the angle of attack are calculated through the aerodynamic geometric relationship, the torsion law of the blade is determined according to the change of the inflow angle along the radial direction, each blade element works at the design angle of attack, and the installation angle change curve of the blade along the radial direction is output.

[0016] Further, the chord length distribution and the installation angle distribution are input, the NACA airfoil family suitable for the blade section is selected, the upper and lower surface coordinates and the camber line coordinates of the airfoil are generated according to the airfoil definition equation, the actual size is scaled according to the chord length, and the complete section geometric model of the blade from the root to the tip is formed combined with the relative thickness change law along the radial direction, and the three-dimensional coordinate data of each radial section of the blade is obtained.

[0017] Further, based on the three-dimensional geometric model, the chord-wise grid division number and the radial direction division number are set according to the structural analysis precision requirement; In the radial direction, a blade section is generated In the chord direction, the three-dimensional coordinates, the normal direction and the tangential direction of each node are calculated, and the local coordinate system is established, after the node data is completed, the quadrilateral 8-node shell element grid is generated according to the node connection relationship, and the node and element data are output.

[0018] Further, input the node and element data, and establish the coordinate mapping equation and displacement interpolation function of the 8-node shell element based on the isoparametric element method. Through the strain-displacement relationship and stress-strain relationship, the stiffness matrix and mass matrix of the shell element are derived by using the virtual work principle. The shape function matrix is defined by the node displacement and geometric coordinates. The element stiffness matrix and mass matrix of the propeller blade are output.

[0019] Further, the stiffness matrix and mass matrix are input, the material parameters and boundary conditions of the blade are combined, the dynamic control equation of the propeller blade is established, the modal analysis and dynamic response analysis of the structure are completed by introducing the Rayleigh damping matrix, and the dynamic characteristics of the blade, i.e. the natural frequency, mode shape distribution and dynamic characteristics of the blade, are obtained.

[0020] Further, the geometric parameters include: propeller diameter, hub radius, number of blades, design speed, flight speed, target thrust and design tension.

[0021] Further, the node and element data include: node coordinates, local coordinate system, thickness information and element connection relationship.

[0022] A parametric propeller modeling system based on shell elements, the system comprising:

[0023] A design parameter confirmation module: according to the design task book and working condition of the aircraft, the basic design parameters of the propeller are determined, and the overall geometric boundary parameters and design working condition of the propeller are obtained;

[0024] A blade chord length distribution calculation module: based on the geometric boundary parameters, the chord length change along the radial direction of the blade is calculated according to the aerodynamic load distribution law and the demand for propulsive efficiency, and the chord length distribution curve of the blade is obtained;

[0025] A blade installation angle calculation module: taking the design working condition and chord length distribution as input, the inflow angle and angle of attack are calculated through aerodynamic geometric relationship, the twist law of the blade is determined according to the change of the inflow angle along the radial direction, so that each blade element works at the design angle of attack, and the installation angle change curve of the blade along the radial direction is output;

[0026] An airfoil selection and profile generation module: input the chord length distribution and installation angle distribution, select the NACA airfoil family as the blade profile, generate the upper and lower surface and camber line coordinates of the airfoil according to the airfoil definition equation, scale the actual size according to the chord length, and form the complete profile geometric model of the blade from the root to the tip in combination with the relative thickness change law along the radial direction, to obtain the three-dimensional coordinate data of each radial section of the blade;

[0027] A mesh generation module: based on the three-dimensional coordinate data, the chord-wise mesh division number and the radial mesh division number are set according to the structural analysis accuracy requirement . ; generating in radial direction ; dividing in chordwise direction ; calculating three-dimensional coordinates, mean camber line normal and tangent directions of each node, and establishing a local coordinate system, after the node data is completed, generating quadrilateral 8-node shell element grid according to the node connection relationship, outputting node and element data;

[0028] Finite element model establishment module: input the node and element data, establish the coordinate mapping equation and displacement interpolation function of the 8-node shell element based on the isoparametric element method, derive the stiffness matrix and mass matrix of the shell element by using the virtual work principle through the strain-displacement relationship and stress-strain relationship, define the shape function matrix by the node displacement and geometric coordinates, output the element stiffness matrix and mass matrix of the propeller blade;

[0029] Dynamics analysis module: taking the stiffness matrix and mass matrix as input, combining with the blade material parameters and boundary conditions, establishing the dynamics control equation of the propeller blade, completing the structural modal analysis and dynamic response analysis by introducing the Rayleigh damping matrix, obtaining the natural frequency, mode shape distribution and dynamic characteristics of the blade.

[0030] Compared with the prior art, the propeller design method has the following advantages:

[0031] Efficient design process:

[0032] The method can quickly generate a finite element model of the propeller through a systematic parametric design process. Through digital modeling, the design efficiency is significantly improved, and compared with the traditional manual modeling method, the development time and cost are reduced.

[0033] Superior aerodynamic performance and economy:

[0034] By accurately calculating the chord length distribution, inflow angle, angle of attack and installation angle of the blade, the blade is ensured to operate under optimal aerodynamic conditions, which has the potential to improve propulsion efficiency, thereby reducing fuel consumption and improving range, and increasing economy.

[0035] High adaptability:

[0036] The design method of NACA airfoil family is adopted, which ensures that the blade has good aerodynamic characteristics and is suitable for the specific needs of various aircraft. This design method is flexible and can adapt to different types and purposes of propellers.

[0037] Accurate structural analysis:

[0038] The shell element model established based on the isoparametric element theory makes the calculation of the stiffness and mass matrix of the blade more accurate, which can accurately reflect the dynamic behavior of the blade under complex aerodynamic environment and provide solid data support for structural strength analysis.

[0039] System dynamics analysis capabilities:

[0040] This method allows for comprehensive dynamic response analysis and modal analysis of the blade, which can effectively evaluate the vibration characteristics and fatigue life of the blade in actual flight, and improve the consideration of safety in the design process.

[0041] Automation and parametric design:

[0042] This method has high automation capability, which can automatically generate models and analysis results by inputting parameters, simplifying the workload of designers, reducing the possibility of human error, and improving the repeatability and consistency of design.

[0043] Support innovation and research and development:

[0044] A new modeling and analysis method is provided, which promotes the research and development of propeller technology and provides a foundation for future design innovation, opening up new paths for more efficient aviation propulsion technology exploration. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 , wing profile upper and lower edge coordinate definition diagram;

[0046] Figure 2 , blade shell element model diagram;

[0047] Figure 3 , blade cantilever condition natural frequency and mode shape diagram. DETAILED DESCRIPTION

[0048] The specific embodiments of the present application will be described below in conjunction with the embodiments:

[0049] It should be noted that the structures, proportions, sizes, etc. shown in the present specification are only used to cooperate with the content disclosed in the specification, so that those skilled in the art can understand and read, and are not used to limit the limiting conditions of the implementation of the present application. Any modification of structure, change of proportion relationship or adjustment of size, which does not affect the effect and purpose that can be achieved by the present application, should still fall within the scope of the technical content disclosed by the present application.

[0050] At the same time, the terms such as "up", "down", "left", "right", "middle" and "one" referred to in the present specification are only for the convenience of clear description, and are not used to limit the scope of the present application. The change or adjustment of the relative relationship, without substantial change of technical content, is also regarded as the implementation scope of the present application.

[0051] Example 1:

[0052] In one exemplary embodiment, the present application proposes a detailed step of a shell element-based parameterized propeller modeling method, which takes propeller geometry and aerodynamic parameters as input, goes through a complete process of geometry modeling → airfoil determination → mesh division → shell element modeling → dynamic equation establishment → dynamic analysis, and forms an automatic and parameterized design path from parameters to finite element model. Compared with traditional three-dimensional modeling methods, the present method has the advantages of direct generation of shell element model from parameter input, high calculation accuracy and high analysis efficiency, and can significantly improve the engineering application efficiency of propeller dynamics simulation; specifically including the following steps:

[0053] 1) According to the working conditions required by the aircraft, the propeller diameter, hub radius, blade number and the like are determined.

[0054] 2) The chord length varies radially, and the relative chord length is determined by formula (1).

[0055] (1)

[0056] 3) The blade installation angle is the angle between the chord line of the element profile and the rotation plane, the angle of attack is the angle between the chord line of the element profile and the relative airflow velocity direction, and the inflow angle is the angle between the geometric synthesis speed and the rotation plane. The inflow angle is calculated by formula (2).

[0057] (2)

[0058] The element angle of attack is:

[0059] (3)

[0060] Under normal working conditions, the angle of attack of the airfoil is positive, in order to make the entire propeller element work at a favorable angle of attack, it is necessary to twist the blade along the radial direction. Since the airflow inflow angle varies along the radial direction, the element installation angle varies along the radial direction of the blade. The common angle of attack value is 5°~25°, because the airflow inflow angle is large, in order to simplify the structure, the angle of attack is taken as a fixed value of 6°.

[0061] 4) Select NACA (National Advisory Committee for Aeronautics) airfoil for the blade airfoil, and the coordinate definition of the airfoil is as shown in Figure 1 .

[0062] As shown in Figure 1 , the upper and lower surface curves of the airfoil are expressed as functions of the relative coordinates of the chord line, that is, and . Here, is also the relative value of the chord length . Similarly, the camber line of the airfoil is also expressed as a function of the relative coordinates of the chord line, that is Therefore, the thickness of the airfoil ,thickness For chord length The relative value is It is usually expressed as a percentage; relative curvature is It is usually expressed as a percentage. The line connecting the point on the middle arc to the origin and... The included angle of the axis.

[0063] Therefore, it can be concluded that the curves of the upper and lower surfaces of the airfoil are related to... , , The parametric equation is shown in formula (4).

[0064] (4)

[0065] The NACA airfoil was proposed by NASA after extensive and systematic research on airfoils. NACA comprises many series, each with different thickness and camber distributions, resulting in excellent aerodynamic performance. The thickness distribution formula for the NACA airfoil family is:

[0066] (5)

[0067] The mid-arc is a parabola consisting of two segments that are tangent at the highest point:

[0068] (6)

[0069] in, For the thickness of the airfoil, Let be the ordinate of the highest point of the middle arc. Let x be the x-coordinate of the highest point of the middle arc. Given... , and The value can then be used to obtain an airfoil family.

[0070] NACA airfoils are expressed using either four or five digits. In four-digit airfoil families, the first digit represents the percentage of the chord length. The second digit is a tenth of the chord length, representing... The last two digits represent the percentage of the chord length. Multiplying the obtained relative airfoil coordinates by the chord length will magnify them to the true airfoil coordinates. For example, NACA 4406 represents an airfoil family where the ordinate of the highest point of the mid-curve is 4%, the abscissa of the highest point of the mid-curve is 40%, and the thickness is 6%. Basic information such as the airfoil's thickness, camber, and the location of maximum camber can be obtained from the airfoil number.

[0071] Any cross section of the blade Maximum thickness at The thickness of the blade is called its thickness. Generally, the blade thickness decreases monotonically along the radial direction from the root to the tip. The ratio of the blade thickness to the blade chord length is called the relative thickness of the blade. To improve propeller efficiency, thinner blades are typically used, but this results in poorer aerodynamic characteristics in the stall region. The relative thickness of the metal blade tip is usually set at 4% to 7%. The approximate curve for the relative thickness of the blades in this design is as follows:

[0072] (7)

[0073] 5) After determining the structural parameters of the blades, such as Figure 2 As shown, the blade is modeled using shell elements. First, the mesh density of the blade shell elements is determined and set as nx and ny, where nx is the number of elements in the chord direction and ny is the number of elements in the radial direction.

[0074] There are ny elements in the radial direction, which means there are ny+1 blade element sections. A uniform mesh is used, and the blade element sections are calculated at equal intervals from the blade root to the blade tip. Within each blade element section, nx elements are divided along the chord length, resulting in nx+1 points at equal intervals along the chord length. The coordinates of each point lie on the mid-arc line connecting the midpoints of the upper and lower surfaces of the blade element section. Each point on the blade element section is numbered, and the thickness of each point within the blade element section is calculated to provide parameters for building the finite element model. To ensure accurate representation of the blade's dynamic characteristics, the mesh density can be slightly higher. For each node, the normal to the mid-arc line and the tangent plane of the mid-arc line need to be calculated. A local coordinate system is established using the normal and the tangent plane for subsequent shell element creation. After numbering the nodes and recording the 3D coordinates, local coordinate system, and thickness of each node, the nodes are connected to form several quadrilateral elements, which are then numbered. The eight node numbers corresponding to each element are also recorded.

[0075] 6) After completing the mesh generation, the finite element model of the blade is established using the following shell element theory.

[0076] For an 8-node shell element, the coordinate equations of any point within the element are defined using the isoparametric element method.

[0077] (8)

[0078] The definition rule for this formula is as follows: Assuming the shell elements have the same displacement in the thickness direction, the coordinate problem is actually a planar problem. Therefore, we first define an 8-node isoparametric element in the plane, where the coordinate variables of the parent element are... Thus, the plane is obtained Coordinates. Regarding the thickness direction, The thickness of the surface at each node, The coordinates are in the parent element. Since the thickness direction is simply defined, the mapping between the parent element and the child element is linear.

[0079] For an 8-node shell element, the displacement of any point within the element can be obtained through shape function interpolation:

[0080] (9)

[0081] The first term on the right-hand side of the equation represents the displacement values ​​of each node. Applying the isoparametric element method to these values ​​yields the displacement of any node within the shell element on the shell's mid-plane. The right-hand side of the equation represents the influence of the shell element's thickness and the rotational degrees of freedom of the nodes within the element on the displacement of any point within the shell element. Indicates the angular displacement of the node. The matrix defines the direction of the influence of the rotational angular displacement of a node on the node displacement.

[0082] The strain-displacement relationship of the 8-node shell element can be obtained using formula (9).

[0083] (10)

[0084] The stress-strain relationship is as follows:

[0085] (11)

[0086] Based on the principle of virtual work, the stiffness matrix expression for an N-node shell element is derived as follows:

[0087] (12)

[0088] The mass matrix expression for an N-node shell element is:

[0089] (13)

[0090] Among them, the shape function matrix is ​​the matrix expression of the displacement-node coordinate relationship, as shown in formula (14).

[0091] For a node with 5 displacements, the shape function is:

[0092] (14)

[0093] 7) Based on the structural parameters of the propeller blade, complete the 8-node shell element mesh generation of the blade, and obtain the mass matrix and stiffness matrix of the blade shell element model through shell element theory, and establish the following dynamic equations.

[0094] (15)

[0095] After inputting the stiffness matrix and mass matrix, and calculating the Rayleigh damping matrix, dynamic analysis can be performed on the blade shell element model, such as... Figure 3 As shown.

[0096] Example 2:

[0097] This invention provides a shell-element-based parametric propeller modeling system, which can be used to implement the aforementioned shell-element-based parametric propeller modeling method. Specifically, it includes:

[0098] Design parameter confirmation module: Based on the aircraft's design task book and operating conditions, determine the basic design parameters of the propeller and obtain the overall geometric boundary parameters and design operating conditions of the propeller.

[0099] Blade chord length distribution calculation module: Based on the geometric boundary parameters, according to the aerodynamic load distribution law and propulsion efficiency requirements, calculate the chord length variation of the blade along the radial direction to obtain the blade chord length distribution curve;

[0100] Blade installation angle calculation module: Taking the design conditions and chord length distribution as input, it calculates the inflow angle and angle of attack through aerodynamic geometry. Based on the change of the inflow angle along the radial direction, it determines the torsional law of the blade, so that each blade element works at the design angle of attack, and outputs the installation angle change curve of the blade along the radial direction.

[0101] Airfoil selection and profile generation module: Input the chord length distribution and installation angle distribution, select the appropriate NACA airfoil family as the blade profile, generate the coordinates of the upper and lower surfaces and the mid-arc line of the airfoil according to the airfoil definition equation, scale the actual size according to the chord length, and combine the radial relative thickness variation law to form a complete cross-sectional geometric model of the blade from the root to the tip, and obtain the three-dimensional coordinate data of each radial section of the blade.

[0102] Mesh generation module: Based on the aforementioned 3D coordinate data, sets the number of chordal mesh divisions according to the structural analysis accuracy requirements. With radial division number Generate in the radial direction Each leaf element section is divided in the chord direction. Each node is assigned a number of nodes. The 3D coordinates, mid-arc normal, and tangential direction of each node are calculated, and a local coordinate system is established. After the node data is completed, a quadrilateral 8-node shell element mesh is generated based on the node connection relationship, and the node and element data are output.

[0103] Finite element model establishment module: Input the node and element data, establish the coordinate mapping equation and displacement interpolation function of the 8-node shell element based on the isoparametric element method, derive the shell element stiffness matrix and mass matrix by means of strain-displacement relationship and stress-strain relationship, and use the principle of virtual work. The shape function matrix is ​​defined by the node displacement and geometric coordinates, and outputs the element stiffness matrix and mass matrix of the propeller blade.

[0104] Dynamics Analysis Module: Using the stiffness matrix and mass matrix as input, and combining the blade material parameters and boundary conditions, the dynamic control equations of the propeller blade are established. By introducing the Rayleigh damping matrix, structural modal analysis and dynamic response analysis are completed to obtain the blade's natural frequency, mode shape distribution, and dynamic characteristics.

[0105] Example 3:

[0106] This embodiment provides a terminal device, which includes a processor and a memory. The memory stores a computer program, which includes program instructions. The processor executes the program instructions stored in the computer storage medium. The processor may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing and control core of the terminal, suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions to achieve a corresponding method flow or corresponding function. The processor described in this embodiment can be used in the operation of a shell-based parametric propeller modeling method, including the following steps:

[0107] S1: Based on the aircraft's design specifications and operating conditions, determine the basic design parameters of the propeller and obtain the overall geometric boundary parameters and design operating conditions of the propeller.

[0108] S2: Based on the geometric boundary parameters, according to the aerodynamic load distribution law and propulsion efficiency requirements, calculate the chord length variation of the blade along the radial direction to obtain the blade chord length distribution curve;

[0109] S3: Using the design conditions and chord length distribution as input, calculate the inflow angle and angle of attack through aerodynamic geometry. Based on the change of the inflow angle along the radial direction, determine the torsional law of the blade, so that each blade element works at the design angle of attack, and output the installation angle change curve of the blade along the radial direction.

[0110] S4: Input the chord length distribution and installation angle distribution, select the appropriate NACA airfoil family as the blade profile, generate the coordinates of the upper and lower surfaces and the mid-arc line of the airfoil according to the airfoil definition equation, scale the actual size according to the chord length, and combine the radial relative thickness variation law to form a complete cross-sectional geometric model of the blade from the root to the tip, and obtain the three-dimensional coordinate data of each radial section of the blade.

[0111] S5: Based on the aforementioned three-dimensional coordinate data, determine the number of chordal mesh divisions according to the structural analysis accuracy requirements. With radial division number Generate in the radial direction Each leaf element section is divided in the chord direction. Each node is assigned a number of nodes. The 3D coordinates, mid-arc normal, and tangential direction of each node are calculated, and a local coordinate system is established. After the node data is completed, a quadrilateral 8-node shell element mesh is generated based on the node connection relationship, and the node and element data are output.

[0112] S6: Input the node and element data, establish the coordinate mapping equation and displacement interpolation function of the 8-node shell element based on the isoparametric element method, derive the shell element stiffness matrix and mass matrix by means of strain-displacement relationship and stress-strain relationship, and use the principle of virtual work. The shape function matrix is ​​defined by the node displacement and geometric coordinates, and output the element stiffness matrix and mass matrix of the propeller blade.

[0113] S7: Using the stiffness matrix and mass matrix as input, and combining the blade material parameters and boundary conditions, establish the dynamic control equations of the propeller blade. By introducing the Rayleigh damping matrix, complete the structural modal analysis and dynamic response analysis to obtain the blade's natural frequency, mode shape distribution, and dynamic characteristics.

[0114] Example 4:

[0115] This embodiment provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a terminal device used to store programs and data. It is understood that the computer-readable storage medium here can include both the built-in storage medium in the terminal device and extended storage media supported by the terminal device. The computer-readable storage medium provides storage space that stores the terminal's operating system. Furthermore, this storage space also stores one or more instructions suitable for loading and execution by a processor. These instructions can be one or more computer programs (including program code). It should be noted that the computer-readable storage medium here can be high-speed RAM or non-volatile memory, such as at least one disk storage device.

[0116] One or more instructions stored in a computer-readable storage medium can be loaded and executed by a processor to implement the corresponding steps of the parameterized propeller modeling method based on shell units in the above embodiments; one or more instructions in the computer-readable storage medium are loaded and executed by the processor to perform the following steps:

[0117] S1: Based on the aircraft's design specifications and operating conditions, determine the basic design parameters of the propeller and obtain the overall geometric boundary parameters and design operating conditions of the propeller.

[0118] S2: Based on the geometric boundary parameters, according to the aerodynamic load distribution law and propulsion efficiency requirements, calculate the chord length variation of the blade along the radial direction to obtain the blade chord length distribution curve;

[0119] S3: Using the design conditions and chord length distribution as input, calculate the inflow angle and angle of attack through aerodynamic geometry. Based on the change of the inflow angle along the radial direction, determine the torsional law of the blade, so that each blade element works at the design angle of attack, and output the installation angle change curve of the blade along the radial direction.

[0120] S4: Input the chord length distribution and installation angle distribution, select the appropriate NACA airfoil family as the blade profile, generate the coordinates of the upper and lower surfaces and the mid-arc line of the airfoil according to the airfoil definition equation, scale the actual size according to the chord length, and combine the radial relative thickness variation law to form a complete cross-sectional geometric model of the blade from the root to the tip, and obtain the three-dimensional coordinate data of each radial section of the blade.

[0121] S5: Based on the aforementioned three-dimensional coordinate data, determine the number of chordal mesh divisions according to the structural analysis accuracy requirements. With radial division number Generate in the radial direction Each leaf element section is divided in the chord direction. Each node is assigned a number of nodes. The 3D coordinates, mid-arc normal, and tangential direction of each node are calculated, and a local coordinate system is established. After the node data is completed, a quadrilateral 8-node shell element mesh is generated based on the node connection relationship, and the node and element data are output.

[0122] S6: Input the node and element data, establish the coordinate mapping equation and displacement interpolation function of the 8-node shell element based on the isoparametric element method, derive the shell element stiffness matrix and mass matrix by means of strain-displacement relationship and stress-strain relationship, and use the principle of virtual work. The shape function matrix is ​​defined by the node displacement and geometric coordinates, and output the element stiffness matrix and mass matrix of the propeller blade.

[0123] S7: Using the stiffness matrix and mass matrix as input, and combining the blade material parameters and boundary conditions, establish the dynamic control equations of the propeller blade. By introducing the Rayleigh damping matrix, complete the structural modal analysis and dynamic response analysis to obtain the blade's natural frequency, mode shape distribution, and dynamic characteristics.

[0124] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied 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.

[0125] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0126] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0127] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0128] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

[0129] Many other changes and modifications can be made without departing from the concept and scope of this invention. It should be understood that this invention is not limited to the specific embodiments, and the scope of this invention is defined by the appended claims.

Claims

1. A parameterized propeller modeling method based on shell elements, characterized in that, The parameterized propeller modeling method comprises: According to the design task and working condition of the aircraft, the geometric parameters and design conditions of the propeller are determined; Based on the geometric parameters, the chord length distribution of the blade along the radial direction is calculated; According to the design working condition and the chord length distribution, the inflow angle and the angle of attack are calculated, and the installation angle distribution of the blade along the radial direction is determined; According to the chord length distribution and the installation angle distribution, the airfoil is selected and the blade section coordinate is established, and the three-dimensional geometric model of the blade is generated; Based on the three-dimensional geometric model, the grid is divided, the node coordinates and element connection relationship of the blade are established, and the shell element finite element grid is formed; based on the isoparametric element theory, the shell element model is established, and the stiffness matrix and mass matrix of the blade are calculated; The stiffness matrix and mass matrix are used to establish the dynamic equation, and the modal and dynamic response analysis is carried out to obtain the dynamic characteristics of the blade.

2. The parameterized propeller modeling method of claim 1, wherein, Based on the geometric parameters, according to the aerodynamic load distribution law and the demand of propulsive efficiency, the chord length change of the blade along the radial direction is calculated to obtain the chord length distribution curve of the blade.

3. The parameterized propeller modeling method of claim 1, wherein, Taking the design conditions and chord length distribution as input, the inflow angle and the angle of attack are calculated through aerodynamic geometry relationship, the twist law of the blade is determined according to the change of the inflow angle along the radial direction, so that each blade element works at the design angle of attack, and the installation angle change curve of the blade along the radial direction is output.

4. The parameterized propeller modeling method of claim 1, wherein, The chord length distribution and installation angle distribution are input, the NACA airfoil family suitable for the blade section is selected, the upper and lower surface and camber line coordinates of the airfoil are generated according to the airfoil definition equation, the actual size is scaled according to the chord length, and the complete section geometric model of the blade from the root to the tip is formed combined with the relative thickness change law along the radial direction, so as to obtain the three-dimensional coordinate data of each radial section of the blade.

5. The parameterized propeller modeling method of claim 1, wherein, Based on the three-dimensional geometric model, according to the structure analysis accuracy requirement, set the chordwise grid division number With radial division number ; Radial direction generates Ridge section, chordwise direction divides Node, calculate the three-dimensional coordinates, mean arc line normal and tangential direction of each node, and establish a local coordinate system. After the node data is completed, generate quadrilateral 8-node shell element grid according to the node connection relationship, and output node and element data.

6. The parameterized propeller modeling method of claim 1, wherein, The node and element data are input, the coordinate mapping equation and displacement interpolation function of 8-node shell element are established based on isoparametric element method, the stiffness matrix and mass matrix of shell element are derived by using virtual work principle through strain-displacement relationship and stress-strain relationship, the shape function matrix is defined by node displacement and geometric coordinates, and the element stiffness matrix and mass matrix of the propeller blade are output.

7. The parameterized propeller modeling method of claim 1, wherein, Taking the stiffness matrix and mass matrix as input, combined with the material parameters and boundary conditions of the blade, the dynamic control equation of the propeller blade is established, the modal analysis and dynamic response analysis are completed by introducing Rayleigh damping matrix, and the dynamic characteristics of the blade, i.e. the natural frequency, mode shape distribution and dynamic characteristics of the blade are obtained.

8. The parameterized propeller modeling method of claim 1, wherein, The geometric parameters include: propeller diameter, hub radius, number of blades, design speed, flight speed, target thrust and design tension.

9. The parametric propeller modeling method of claim 5 or 6, wherein, The node and element data include: node coordinates, local coordinate system, thickness information and element connection relationship.

10. A parameterized propeller modeling system based on shell elements, characterized by, The system comprises: A design parameter confirmation module: according to the design task book and working condition of the aircraft, the basic design parameters of the propeller are determined to obtain the overall geometric boundary parameters and design working condition of the propeller; A blade chord length distribution calculation module: based on the geometric boundary parameters, according to the aerodynamic load distribution law and the demand of propulsive efficiency, the chord length change of the blade along the radial direction is calculated to obtain the chord length distribution curve of the blade; The blade installation angle calculation module: taking the design working condition and the chord length distribution as input, calculating the inflow angle and the angle of attack through aerodynamic geometry relationship, determining the twist law of the blade according to the change of the inflow angle along the radial direction, making each blade element work at the design angle of attack, and outputting the change curve of the installation angle of the blade along the radial direction; The airfoil selection and profile generation module: inputting the chord length distribution and the installation angle distribution, selecting the adaptive NACA airfoil family as the blade profile, generating the coordinates of the upper surface and the lower surface of the airfoil and the camber line according to the airfoil definition equation, scaling the actual size according to the chord length, and combining the relative thickness change law along the radial direction to form the complete profile geometry model of the blade from the root to the tip, and obtaining the three-dimensional coordinate data of each radial section of the blade; The grid generation module: based on the three-dimensional coordinate data, according to the structure analysis accuracy requirement, set the chordal grid division number With radial division number ; Radial direction generates A leaflet section, chordal direction divides Node, calculate the three-dimensional coordinates, mean arc line normal and tangential direction of each node, and establish a local coordinate system, after the node data is completed, generate quadrilateral 8-node shell element grid according to the node connection relationship, output node and element data; The finite element model establishment module: inputting the node and element data, establishing the coordinate mapping equation and the displacement interpolation function of the 8-node shell element based on the isoparametric element method, deriving the stiffness matrix and the mass matrix of the shell element through the strain-displacement relationship and the stress-strain relationship, defining the shape function matrix by the node displacement and the geometric coordinates, and outputting the element stiffness matrix and the mass matrix of the propeller blade; The dynamics analysis module: taking the stiffness matrix and the mass matrix as input, combining the blade material parameters and the boundary conditions to establish the dynamics control equation of the propeller blade, completing the modal analysis and the dynamic response analysis by introducing the Rayleigh damping matrix, and obtaining the natural frequency, the mode shape distribution and the dynamic characteristics of the blade.

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