Method for calculating sound and vibration characteristics of multi-section rotary shell under light fluid

Abstract

The invention provides a method for calculating sound and vibration characteristics of a multi-section rotary shell under light fluid, which comprises the following steps of: splitting the multi-section rotary shell into a conical section with a linear generatrix and a hyperbolic section with a nonlinear generatrix according to curvature change characteristics of a meridian line of the shell, and generating node distribution meeting differential quadrature operation in each section; a control equation of the shell is established based on the first-order shear deformation theory, boundary conditions are simulated through an artificial spring, force and displacement continuity of multiple sections of joints is processed, free vibration and forced vibration characteristics are solved through a differential quadrature algorithm, and global speed response is obtained; a fitting unit radiation superposition method is adopted to enable the surface of a shell to be equivalent to an acoustic baffle, a cylindrical surface or a spherical crown surface is adopted to fit and calculate a sound transmission vector according to the type of the shell, and far-field sound radiation characteristics under light fluid are solved in combination with global speed response. The sound and vibration characteristic analysis method provided by the invention has high efficiency, universality and good engineering practicability on the premise of ensuring the calculation precision.

Description

Technical Field

[0001] This invention relates to the field of acoustic characteristic analysis technology, and in particular to a method for calculating the acoustic and vibration characteristics of a multi-segment rotating shell under light fluid conditions. Background Technology

[0002] Multi-segment rotating shell structures, with their excellent aerodynamic performance, have been widely used in aerospace and marine fields such as rocket fairings, cabins, and large pressure vessels. The vibrational acoustic characteristics analysis of rotating shells plays a crucial role in their structural design and optimization, energy dissipation analysis, and prediction of their dynamic performance. For acoustic radiation analysis in light fluid domains, the mainstream methods include numerical methods and theoretical methods. Solving rotating shells with arbitrary meridions primarily relies on numerical methods. Numerical methods often employ finite element methods (FEM) and boundary element methods (BEM), solving complex geometric and multiphysics coupled problems by discretizing the structural and acoustic domains. However, these methods are computationally expensive, highly sensitive to parameters, and often require extensive mesh generation and repetitive modeling when dealing with rotating shells with arbitrary meridions and multi-segment splicing.

[0003] The theoretical approach employs the three-variable Donnell shell theory and the five-variable first-order shear deformation theory in mechanical modeling, and uses methods such as the joint wave superposition method, the element radiation superposition method, and the transfer matrix method in acoustic field solving. These methods can achieve efficient solutions for typical shell structures such as cylindrical, conical, and spherical shells to a certain extent. However, for shells of revolution with complex meridian shapes, irregular curvature changes, and multiple segments, existing theoretical formulas are difficult to apply directly. With the development of the aerospace industry, higher requirements have been placed on the aerodynamic performance of launch vehicles. Traditional shells with specific equations such as parabolas, hyperbolas, and ellipses and conic sections as meridians are gradually being replaced by composite shells with better performance and KAMAN meridians. Existing theoretical methods struggle to uniformly model the structural stiffness matrix, coupling terms, and fluid-structure interaction sound pressure, while numerical methods suffer from high computational complexity and poor convergence.

[0004] Therefore, there is an urgent need for an efficient method that can handle arbitrary meridians, support multi-segment splicing, and perform unified analysis of structural dynamics and airborne acoustic radiation coupling, so as to achieve the generalization, speed and engineering usability of theoretical solutions, and provide a reliable tool for the design, optimization and acoustic control of multi-segment rotating shell structures. Summary of the Invention

[0005] This invention provides a method for calculating the acoustic and vibration characteristics of a multi-segment rotating shell under light fluid conditions, which solves the problems of low efficiency and unsatisfactory accuracy in solving the acoustic radiation characteristics of multi-segment rotating shell structures with arbitrary meridians.

[0006] In a first aspect, the present invention provides a method for calculating the acoustic and vibration characteristics of a multi-segment rotating shell under light fluid conditions, comprising: Based on the curvature variation characteristics of the shell meridian, the multi-segment rotating shell is divided into conical segments with linear generatrices and hyperbolic segments with nonlinear generatrices, and a node distribution that satisfies differential quadrature operation is generated within each segment. The control equations of the shell are established based on the first-order shear deformation theory. Boundary conditions are simulated by artificial springs and the continuity of force and displacement at multiple connection points is handled. The characteristics of free vibration and forced vibration are solved by differential quadrature algorithm to obtain the global velocity response. The shell surface is equivalent to an acoustic baffle by using the fitting element radiation superposition method. The sound transmission vector is calculated by fitting a cylindrical surface or a spherical cap surface according to the shell type. The far-field sound radiation characteristics under light fluid are solved by combining the global velocity response.

[0007] According to the method for calculating the acoustic and vibration characteristics of a multi-segment rotating shell under light fluid conditions provided by the present invention, the generation of a node distribution that satisfies the differential quadrature operation includes: for the conical segment, the Chebyshev node distribution method is used to determine the distribution; for the hyperbolic segment, the node calculation specifically includes: discretizing the meridian into a set of data points, calculating the angle between the meridian normal and the axis of rotation using the first-order finite difference method; obtaining the angle value corresponding to the differential quadrature node through Chebyshev interpolation, and obtaining the coordinates of the differential quadrature node through interpolation.

[0008] According to the method for calculating the acoustic and vibration characteristics of a multi-segment rotating shell under light fluid conditions provided by the present invention, the governing equation is a five-variable coupled equation including mid-surface displacement and rotation angle; the solution of the governing equation includes boundary condition processing, which is simulated by setting artificial springs and based on the continuity condition of force and displacement to handle the coupling at the connection of the multi-segment.

[0009] The method for calculating the acoustic and vibration characteristics of a multi-segment rotating shell under light fluid conditions provided by the present invention employs a fitting element radiation superposition method to treat the shell surface as an equivalent acoustic baffle. Depending on the shell type, a cylindrical surface or a spherical cap surface is used to fit and calculate the acoustic transmission vector. This includes: dividing the shell surface into multiple radiation elements; for linear generatrix shells, a cylindrical surface is used to fit the acoustic transmission vector; for nonlinear generatrix shells, a spherical cap surface is used to fit the acoustic transmission vector; and for different types of acoustic baffles, corresponding calculation formulas containing Hankel functions, spherical Hankel functions, Legendre functions, and spherical Bessel functions are used to calculate the acoustic transmission matrix.

[0010] According to the method for calculating the acoustic and vibration characteristics of a multi-segment rotating shell under light fluid conditions provided by the present invention, for a linear generatrix shell, the acoustic transmission vector is fitted using a cylindrical surface, including: for a cylindrical surface, a preset cylindrical baffle model is directly used to fit the acoustic transmission vector; for a conical surface, it is equivalent to a cylindrical surface with a midpoint radius, and then the preset cylindrical baffle model is used to fit the acoustic transmission vector; for a nonlinear generatrix shell (i.e., a hyperbolic shell), it is divided into meshes and fitted to a spherical cap surface according to different meshes, and then the spherical cap baffle model is used to fit the acoustic transmission vector.

[0011] The method for calculating the acoustic and vibration characteristics of a multi-segment rotating shell under light fluid conditions provided by the present invention is applicable to multi-segment spliced ​​shell structures in rocket fairings, cabins, and pressure vessels.

[0012] Secondly, the present invention also provides a device for calculating the acoustic and vibration characteristics of a multi-segment rotating shell under light fluid conditions, comprising: The first processing module is used to divide the multi-segment rotating shell into conical segments with linear generatrices and hyperbolic segments with nonlinear generatrices according to the curvature variation characteristics of the shell meridian, and generate a node distribution that satisfies differential quadrature operation within each segment; The second processing module is used to establish the control equations of the shell based on the first-order shear deformation theory, simulate boundary conditions through artificial springs and handle the force and displacement continuity at multiple connection points, and use differential quadrature algorithm to solve the free vibration and forced vibration characteristics to obtain the global velocity response. The third processing module is used to treat the shell surface as an equivalent acoustic baffle by using the fitting unit radiation superposition method. Depending on the shell type, the sound transmission vector is calculated by fitting a cylindrical surface or a spherical cap surface, and the far-field sound radiation characteristics under light fluid are solved by combining the global velocity response.

[0013] Thirdly, the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the method for calculating the acoustic and vibration characteristics of a multi-segment rotating shell under light fluid conditions as described above.

[0014] Fourthly, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method for calculating the acoustic and vibration characteristics of a multi-segment rotating shell under light fluid conditions as described above.

[0015] This invention effectively overcomes the limitations of existing numerical methods, such as high computational cost and poor versatility, as well as the difficulty of theoretical methods in handling complex geometries. It successfully realizes an acoustic vibration characteristic analysis method that combines high efficiency, versatility, and good engineering applicability while ensuring computational accuracy. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is one of the flowcharts illustrating the method for calculating the acoustic and vibration characteristics of a multi-segment rotating shell under light fluid conditions provided by the present invention. Figure 2 This is the second flowchart illustrating the method for calculating the acoustic and vibration characteristics of a multi-segment rotating shell under light fluid conditions provided by this invention. Figure 3 This is a diagram defining the global and local coordinate systems for the conical and hyperbolic segments provided by this invention. Figure 4 This is a schematic diagram of the boundary conditions for the continuity of force and displacement between the artificial spring and the shell provided by the present invention; Figure 5 This is a schematic diagram of the differential quadrature node obtained by the data-driven enhanced differential quadrature algorithm provided by the present invention; Figure 6 This is a comparison chart of the velocity-frequency response calculated using the data-driven enhanced differential quadrature algorithm provided by this invention and the finite element method. Figure 7 This is a comparison diagram of the far-field acoustic radiation response in light fluids calculated using the fitting element radiation superposition algorithm provided by this invention and the boundary element method. Figure 8 This is a schematic diagram of the structure of the electronic device provided by the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0019] It should be noted that, in the description of the embodiments of the present invention, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0020] The terms "first," "second," etc., used in this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more.

[0021] The following is combined Figures 1-8 This invention describes the method and apparatus for calculating the acoustic and vibration characteristics of a multi-segment rotating shell in a light fluid environment, as provided in embodiments of the present invention.

[0022] Figure 1 This is one of the flowcharts illustrating the method for calculating the acoustic and vibration characteristics of a multi-segment rotating shell under light fluid conditions provided by the present invention. Figure 2 This is the second flowchart illustrating the method for calculating the acoustic and vibration characteristics of a multi-segment rotating shell under light fluid conditions provided by this invention. Figure 1 and 2 As shown, for multi-segment rotary composite shell structures, based on different meridian types, the free vibration and forced vibration characteristics of conical shells and hyperbolic shells are solved using differential quadrature methods and data-driven enhanced differential quadrature methods, respectively. After obtaining the global velocity response, the shell elements are equivalent to different acoustic barriers using the fitting element radiation superposition method to conduct coupled acoustic vibration characteristic analysis. This includes, but is not limited to, the following steps: Step 101 (Multi-segment Rotation Shell Structure Decomposition): Based on the curvature variation characteristics of the shell meridian, the multi-segment rotation shell is divided into conical segments with linear generatrices and hyperbolic segments with nonlinear generatrices, and a node distribution that satisfies differential quadrature operations is generated within each segment.

[0023] Based on the curvature variation characteristics of the shell meridian, the conical segments (including cylindrical segments) with linear generatrices and the hyperbolic segments with nonlinear generatrices are identified, and a node distribution that satisfies the differential quadrature operation is generated within each segment. Figure 3This is a diagram defining the global and local coordinate systems for the conical and hyperbolic segments provided by this invention, as shown below. Figure 3 As shown, the differential quadrature nodes of the conical shell are defined on the generatrix. A rectangular coordinate system is constructed with the origin at the starting point of the generatrix, and the direction of the generatrix is ​​used as the coordinate system. x The shell is parameterized along the positive axis. Wherein, R This indicates the perpendicular distance between this point and the axis of rotation. The subscripts L, R, and 0 represent the left end, right end, and any other position, respectively. In a total of... N Given the number of differential integration nodes, the first... i c The differential quadrature nodes Coordinates can be defined as: (1) in, L Let be the generatrix length of the conical shell. For hyperbolic shell models, such as... Figure 3 As shown, the rectangular coordinate system constructed in the conical shell will be converted into a curve parametric coordinate system, with subscripts... φ This represents the radius of curvature of the generatrix along the meridian. The meridian is discretized into a set of data points in an orthogonal rectangular coordinate system (…). x 1, x 2, x 3) Below, denote the data point set in its... x The coordinates within the plane 2=0 are , j =1,2,…, n ,in n Let be the size of the data point set. This is determined using the first-order finite difference method. n -1 The angle between the meridian normal corresponding to the data point and the axis of rotation φ j Value: (2) Similarly, using Chebyshev's method, the first i d The corresponding differential quadrature nodes The value can be calculated as: (3) The above formula establishes... The relationship between coordinates is calculated through interpolation. Corresponding coordinates of the differential quadrature nodes After obtaining the coordinates of each differential quadrature node, for the conical shell model, the required parameters at each node can be obtained directly; for the hyperbolic shell model, the finite difference method is used to calculate the required parameters at the nodes.

[0024] Step 102 (Solving free and forced vibration characteristics using differential quadrature algorithm): Establish the control equations of the shell based on the first-order shear deformation theory, simulate boundary conditions using artificial springs and handle the continuity of force and displacement at multiple connection points, solve free and forced vibration characteristics using differential quadrature algorithm, and obtain the global velocity response.

[0025] Based on the first-order shear deformation theory, using the generalized Hooke's law and Hamilton's principle, the unified governing equations for conical shells and hyperbolic shells can be expressed as: (4) in L ij ( i , j =1, 2, 3, 4, 5) are differential operators. u 0, v 0, w 0 represents the displacement of the shell's mid-surface. β x，φ To bypass θ The angle of rotation of the axis, β θ To bypass x Axis (for conical shells) or around φ The rotation angle of the axis (for hyperbolic shells). I 0, I 1, I 2 represents the moment of inertia. After obtaining the governing equations, the boundary condition equations are derived using geometric and force continuity conditions. Figure 4 Is it considering single-point or multi-point harmonic excitation? F The schematic diagram of the force and displacement continuity boundary conditions between the artificial spring and the shell provided by the present invention is as follows: Figure 4 As shown, the left and right boundaries are controlled by artificial springs. By changing the stiffness of the springs, different boundary conditions are simulated. (5) in, N , Q and M These represent the membrane force, shear force, and torque in each direction, respectively. More specifically, N 11 The membrane force represents the force along the meridional direction. N 12 Indicates meridional-circumferential shear force. Q 11 This represents the transverse shear force along the meridian. M 11 Indicates the bending moment in the meridional direction. M 12 Represents torsional moment; for spring stiffness kIn this context, superscripts 0 and 1 represent the left and right ends, respectively; subscripts... l Indicates a wire spring. r This refers to a rotary spring, for example, spring stiffness. This indicates a wire spring on the left boundary. For displacement and force or moment terms, the subscript number... i s Indicates the first i s Joke structure, L and R These represent the left and right ends of a single substructure, for example, N 11,1L This indicates the meridional membrane force at the left end of the first segment. N s This represents the total number of segments in the composite shell. Furthermore, based on the continuity condition of force and displacement, at the connection point of the two rotating structures, considering single-point or multi-point harmonic excitation, boundary conditions are as follows: (6) in, α This indicates the elevation angle of the busbar at the current position, for example, Indicates the first i s The elevation angle of the right-hand generatrix in the segment structure.

[0026] After discretizing the displacement terms by variables and substituting them into the governing equations and boundary condition equations to obtain the coordinate values ​​required at each differential integration node, it can be transformed into a standard eigenvalue equation: (7) in, ω Angular frequency, T This is the coefficient matrix, where the subscript In denotes internal terms and Bo denotes boundary terms. T InIn ],[ T InBo ], [ T BoIn ]and[ T BoBo The dimensions are respectively: N s (5 N -2)× N s (5 N -2), 10 N s × N s (5 N -2), 10 N s ×10 N s and Ns (5 N -2)×10 N s The coefficient matrix. Each displacement term. D In and D Bo It can be represented as: (8-1) (8-2) Among them, U, V, W, B x,φ , B θ These represent displacement terms that are independent of time and natural frequency, and they are related to those in equation (4). u 0, v 0, w 0, β x，φ , β θ This establishes a one-to-one correspondence, which can be further represented as: (9) in n Indicates the modal order. s This indicates the position of the lower housing in the direction of rotation. (Subscript) i s j Indicates the first i s The first sub-segment j For example, a node. U 22 This represents the second differential integration node of the second shell. s =0, t The tangential displacement at time = 0. By solving equation (7), the eigenvectors obtained are the displacements at each differential quadrature node. In the frequency domain, the velocity at the node (i.e., the first derivative of the displacement) can be calculated as: (10) Where i is the imaginary unit.

[0027] Step 103 (Solve acoustic radiation characteristics using the fitting element radiation superposition method): The shell surface is equivalent to an acoustic baffle by using the fitting element radiation superposition method. The acoustic transmission vector is calculated by fitting a cylindrical surface or a spherical cap surface according to the shell type. The far-field acoustic radiation characteristics under light fluid are solved by combining the global velocity response.

[0028] After obtaining the normal vibration velocity distribution of a multi-segment rotating shell structure under external excitation, the Helmholtz surface integral equation is discretized to determine the radiating surface. S Divided into N m One radiating unit (circumferential) N c One, axial N a (a number of points), the position vector of the observation point in the sound field. r At this point, the far-field radiated sound pressure across the entire surface of the structure. p ( r ) and normal vibration velocity vector [ v s The relationship between them can be represented as: (11) in, G It is the sound transmission vector, which depends only on the characteristics of the baffle itself and the far-field sound field observation point, and its expression is: (12) In equation (12), ， i p = 1, 2,…, N m Indicates the first i p The sound pressure radiated by a piston surface to the far-field sound field under unit velocity is calculated. Considering the significant difference in radiation characteristics between linear and nonlinear generatrices, cylindrical and spherical cap surfaces are used for fitting. For cylindrical surfaces, the corresponding formulas are directly substituted for calculation; for conical surfaces, they are equivalent to cylindrical surfaces with the midpoint radius for calculation; for hyperboloids, they are fitted to spherical cap surfaces, and the calculation formula for spherical baffles is considered for calculation. It is assumed that the far-field observation point is in spherical coordinates (…). R , θ , φ Under these conditions, the formulas for calculating the sound transmission vector at this point for both cylindrical and spherical baffles can be expressed as follows: (13) in, ρ 0, c 0 represents the density and sound speed of the light fluid, and velocity. v 0 is the unit velocity v 0 = 1 m / s. For the cylindrical piston surface, 2L0 represents the axial length of the cylindrical piston surface, 2α0 represents the circumferential angle of the cylindrical piston surface, and L1 and α1 represent the current axial and circumferential positions of the piston. For the spherical cap surface, θ0 represents the elevation angle of the piston cap surface.a Represents the radius of the spherical cap. It is the first kind of nth-order spherical Hankel function. It is an nth-order Legendre function. This represents the first kind of m-order Hankel function. This represents the zeroth-order spherical Bessel function.

[0029] At this point, the acoustic transmission vector has been obtained, and the central normal vibration velocity of each baffle can be obtained by interpolation of the velocities at known differential quadrature nodes. Based on this, the far-field acoustic radiation characteristics of the structure under light fluid conditions can be obtained.

[0030] The following describes the embodiments of the present invention in conjunction with the technical solution.

[0031] Consider a three-segment isotropic parabolic shell-cylindrical shell-conical shell model. In the coordinate system (x1, x2, x3), its meridian is defined as: (14) Meridian x One revolution of the axis forms a rotating shell-like structure. The thickness of the combined shell... h =0.02 m, rotational offset R b =0. Mechanical parameters of the material. E =2×10 11 Pa, ν =0.3, ρ =7850 kg / m 3 Stiffness at the boundary k =10 13 Artificial springs of N / m control fixed or free boundary conditions.

[0032] The specific implementation method is as follows: Step 1: Decomposition of the multi-segmented shell structure: The portion where the meridian curvature changes hyperbolically is divided into a hyperboloid shell segment, denoted as segment 1; the interval with constant curvature is divided into conical shell segments, denoted as segments 2 and 3. For segment 1, since the meridian equation of the parabolic shell is known, the equation satisfying the condition can be constructed using the above formula, with a magnitude of... j The data point set with a value of 1000 is defined as follows: Determining using the first-order finite difference method n d -1 The angle between the meridian normal corresponding to the data point and the axis of rotation φ Value: (15) Use Chebyshev method to obtain the corresponding N =31 differential quadrature nodes corresponding to φvalue: (16) Based on the relationship between φ and coordinates established in the above formula, interpolation calculations are performed. Corresponding coordinates of the differential quadrature nodes For segments 2 and 3, local orthogonal rectangular coordinate systems are established at the starting points of the conical and cylindrical shells, respectively. Similarly, the Chebyshev method is used to obtain the corresponding coordinates. N =31 differential quadrature nodes. A total of 93 differential quadrature nodes are obtained through the above steps, as follows: Figure 5 As shown, Figure 5 This is a schematic diagram of the differential quadrature nodes calculated using the data-driven enhanced differential quadrature algorithm provided by this invention. It should be noted that in the process of calculating the hyperbolic shell, this step also requires additional calculation of the parameters needed subsequently using the data points: using the differential quadrature node coordinates and the offset R between the node and the rotation axis. b The radius of rotation R from the differential quadrature node to the rotation axis can be determined. 0i : (17) The first and second order differential terms corresponding to 998 data points are determined using first and second order finite differences: (18) Calculate the radius of curvature of the meridional plane corresponding to each data point using the above differential terms: (19) The above formula establishes... With coordinates The relationship between the nodes is calculated using interpolation to determine the differential. Corresponding to Using the first-order finite difference again, 997 R values ​​can be determined. φ First-order partial derivative with respect to φ: (20) The (dR) established in the above formula φ / dφ) j With φ j The relationship between the nodes is calculated using interpolation to determine the differential. Corresponding to (dR φ / dφ) id . Step 2: Solve for the characteristics of free vibration and forced vibration using the differential quadrature algorithm: Substitute the parameters obtained in step one into the control equations derived based on the five-variable first-order shear deformation theory and Hamilton's principle, as well as the boundary condition equations controlled by artificial springs and continuous boundary conditions. Consider a vertically downward unit force harmonic excitation acting at the junction of the first and second segments, with a circumferential position angle θ = 0. Solve the standard eigenvalue equation derived based on equation (7): (twenty one) By analyzing the aforementioned eigenvalue problem, the modal frequencies, displacement-velocity response, and velocity-frequency response can be obtained. The obtained modal frequencies and velocity-frequency responses are compared with those obtained using the traditional method (finite element method), as shown in Table 1. Figure 6 As shown, Figure 6 This is a comparison chart of the velocity-frequency response calculated using the data-driven enhanced differential quadrature algorithm provided by this invention and the finite element method. Figure 6 The frequency response curves shown are located at the second and third segments, with a circumferential position angle θ = 0.

[0033] Table 1 Modal frequency characteristics of parabolic shell-cylindrical shell-conical shell

[0034] Note: ① Under the boundary condition of double-ended freedom, the first two modes are rigid modes, so they are not considered; ② Consider the case where the axial mode order is 1.

[0035] Step 3: Solve the acoustic radiation characteristics using the fitting element radiation superposition method: For each sub-segment, divide it into circumferential N... c =30, axial N a =20, totaling 600 radiation surfaces. For the first segment, it is fitted as a spherical cap; for the second segment, it is a cylindrical surface; and for the third segment, it is equivalent to a cylindrical surface. Considering its acoustic radiation characteristics at the far-field point (0, 100 m, 0), the normal vibration velocity at the differential quadrature node obtained in step two is interpolated to obtain the normal vibration velocity at each radiation surface position, and finally solved by equation (10). The computation time consumed by this invention in steps two and three is compared with that of the finite element / boundary element method in Table 2.

[0036] Table 2 compares the computation time consumed in steps two (velocity response) and three (acoustic radiation) of this invention with that of the finite element / boundary element method.

[0037] The far-field acoustic radiation results obtained from the solution were compared with those obtained from the finite element / boundary element method. Considering the excessive computation time of the finite element / boundary element method, only the frequency range of 1-100 Hz was used for comparison and analysis. The analysis interval of the finite element / boundary element method was 5 Hz, while the analysis interval of this invention was 1 Hz. The comparison results are as follows: Figure 7 As shown, Figure 7 This is a comparison diagram of the far-field acoustic radiation response in light fluids calculated using the fitting element radiation superposition algorithm provided by this invention and the boundary element method.

[0038] The contents not described in detail in this invention are well-known to those skilled in the art.

[0039] On the other hand, the present invention also provides a device for calculating the acoustic and vibration characteristics of a multi-segment rotating shell under light fluid conditions, comprising: The first processing module is used to divide the multi-segment rotating shell into conical segments with linear generatrices and hyperbolic segments with nonlinear generatrices according to the curvature variation characteristics of the shell meridian, and generate a node distribution that satisfies differential quadrature operation within each segment; The second processing module is used to establish the control equations of the shell based on the first-order shear deformation theory, simulate boundary conditions through artificial springs and handle the force and displacement continuity at multiple connection points, and use differential quadrature algorithm to solve the free vibration and forced vibration characteristics to obtain the global velocity response. The third processing module is used to treat the shell surface as an equivalent acoustic baffle by using the fitting unit radiation superposition method. Depending on the shell type, the sound transmission vector is calculated by fitting a cylindrical surface or a spherical cap surface, and the far-field sound radiation characteristics under light fluid are solved by combining the global velocity response.

[0040] It should be noted that the acoustic and vibration characteristics calculation device for multi-segment rotating shells under light fluid conditions provided in this embodiment of the invention can execute the acoustic and vibration characteristics calculation method for multi-segment rotating shells under light fluid conditions described in any of the above embodiments during specific operation. This embodiment will not elaborate on this aspect.

[0041] Figure 8 This is a schematic diagram of the structure of the electronic device provided by the present invention, such as... Figure 8 As shown, the electronic device may include a processor 810, a communication interface 820, a memory 830, and a communication bus 840. The processor 810, communication interface 820, and memory 830 communicate with each other via the communication bus 840. The processor 810 can call logic instructions from the memory 830 to execute a method for calculating the acoustic and vibration characteristics of a multi-segment rotating shell in light fluid conditions.

[0042] Furthermore, the logical instructions in the aforementioned memory 830 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0043] On the other hand, the present invention also provides a computer program product, the computer program product including a computer program stored on a non-transitory computer-readable storage medium, the computer program including program instructions, and when the program instructions are executed by a computer, the computer is able to execute the method for calculating the acoustic and vibration characteristics of a multi-segment rotating shell under light fluid conditions provided in the above embodiments.

[0044] In another aspect, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to perform the method for calculating the acoustic and vibration characteristics of a multi-segment rotating shell under light fluid conditions provided in the above embodiments.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for calculating the acoustic and vibration characteristics of a multi-segment rotating shell in a light fluid environment, characterized in that, include: Based on the curvature variation characteristics of the shell meridian, the multi-segment rotating shell is divided into conical segments with linear generatrices and hyperbolic segments with nonlinear generatrices, and a node distribution that satisfies differential quadrature operation is generated within each segment. The control equations of the shell are established based on the first-order shear deformation theory. Boundary conditions are simulated by artificial springs and the continuity of force and displacement at multiple connection points is handled. The characteristics of free vibration and forced vibration are solved by differential quadrature algorithm to obtain the global velocity response. The shell surface is equivalent to an acoustic baffle by using the fitting element radiation superposition method. The sound transmission vector is calculated by fitting a cylindrical surface or a spherical cap surface according to the shell type. The far-field sound radiation characteristics under light fluid are solved by combining the global velocity response.

2. The method for calculating the acoustic and vibration characteristics of a multi-segment rotating shell under light fluid conditions according to claim 1, characterized in that, The generation of a node distribution that satisfies the differential quadrature operation includes: For the conical segment, the Chebyshev node distribution method is used to determine it; For hyperbolic segments, node calculation specifically includes: The meridian is discretized into a set of data points, and the angle between the meridian normal and the axis of rotation is calculated using the first-order finite difference method. The included angle value corresponding to the differential quadrature node is obtained by Chebyshev interpolation, and the coordinates of the differential quadrature node are obtained by interpolation.

3. The method for calculating the acoustic and vibration characteristics of a multi-segment rotating shell under light fluid conditions according to claim 1, characterized in that, The governing equations are five-variable coupled equations that include mid-surface displacement and rotation. Solving the governing equations includes boundary condition processing, which is simulated by setting up artificial springs and processing the coupling at multiple connection points based on the continuity conditions of force and displacement.

4. The method for calculating the acoustic and vibration characteristics of a multi-segment rotating shell under light fluid conditions according to claim 1, characterized in that, The shell surface is equivalent to an acoustic baffle using the fitting element radiation superposition method. Depending on the shell type, either a cylindrical surface or a spherical cap surface is used to fit and calculate the sound transmission vector, including: The surface of the shell is divided into multiple radiating units; For linear busbar shells, the acoustic transmission vector is fitted using a cylindrical surface, and the calculation formulas include the spherical Bessel function and the Hankel function. For nonlinear busbar shells, a spherical cap surface is used to fit the sound transmission vector, and the calculation formula includes the spherical Hankel function and the Legendre function.

5. The method for calculating the acoustic and vibration characteristics of a multi-segment rotating shell under light fluid conditions according to claim 4, characterized in that, For linear busbar shells, a cylindrical surface is used to fit the acoustic transmission vector, including: For cylindrical surfaces, a preset cylindrical baffle model is used directly to fit the sound transmission vector; For a conical surface, it is equivalent to a cylindrical surface with a midpoint radius, and then a preset cylindrical baffle model is used to fit the sound transmission vector.

6. The method for calculating the acoustic and vibration characteristics of a multi-segment rotating shell under light fluid conditions according to claim 1, characterized in that, The method is applicable to multi-segment spliced ​​shell structures in rocket fairings, cabins, and pressure vessels.

7. A device for calculating the acoustic and vibration characteristics of a multi-segment rotating shell in a light fluid environment, characterized in that, include: The first processing module is used to divide the multi-segment rotating shell into conical segments with linear generatrices and hyperbolic segments with nonlinear generatrices according to the curvature variation characteristics of the shell meridian, and generate a node distribution that satisfies differential quadrature operation within each segment; The second processing module is used to establish the control equations of the shell based on the first-order shear deformation theory, simulate boundary conditions through artificial springs and handle the force and displacement continuity at multiple connection points, and use differential quadrature algorithm to solve the free vibration and forced vibration characteristics to obtain the global velocity response. The third processing module is used to treat the shell surface as an equivalent acoustic baffle by using the fitting unit radiation superposition method. Depending on the shell type, the sound transmission vector is calculated by fitting a cylindrical surface or a spherical cap surface, and the far-field sound radiation characteristics under light fluid are solved by combining the global velocity response.

8. An electronic 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, it implements the steps of the method for calculating the acoustic and vibration characteristics of a multi-segment rotating shell under light fluid conditions as described in any one of claims 1 to 7.

9. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the method for calculating the acoustic and vibration characteristics of a multi-segment rotating shell under light fluid conditions as described in any one of claims 1 to 7.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the method for calculating the acoustic and vibration characteristics of a multi-segment rotating shell under light fluid conditions as described in any one of claims 1 to 7.

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