Underwater ribbed cylindrical shell sound radiation prediction method and system based on parametric modeling

Abstract

The invention provides an underwater ribbed cylindrical shell sound radiation prediction method and system based on parametric modeling, and the method comprises the following steps: (1) constructing a parametric shell model, and determining geometric parameters, material parameters, rib parameters and fluid parameters; (2) establishing a vibration control equation on the basis of a Donnell-Mushtari shell theory; (3) solving a frequency domain vibration response by adopting a modal superposition method, and calculating a modal amplitude; (4) calculating a sound radiation field based on a Helmholtz integral equation, acquiring near-field sound pressure through numerical integration, and acquiring far-field sound pressure by adopting a modal expansion method; and (5) changing the shell thickness and the excitation amplitude ratio F2 / F1 by optimizing structural parameters and excitation configuration, and observing and analyzing the distribution condition of near-distance radiation noise and the amplitude change condition of a main peak of a long-distance radiation noise level frequency response curve. The calculation method is simple, the real-time analysis effect is good, and technical support can be provided for vibration radiation noise analysis and low-noise structure design of an underwater operation platform and a pipeline structure.

Description

Technical Field

[0001] The present invention belongs to the technical field of underwater structural acoustic performance analysis, and in particular relates to a method and system for predicting the acoustic radiation of an underwater ribbed cylindrical shell based on parametric modeling. Background Art

[0002] Ribbed cylindrical shell structures are widely used in the design and construction of underwater work platforms and pipelines. Factors such as mechanical equipment vibration, propeller rotation, and water impact can cause structural vibration in cylindrical shells, generating internal self-noise and external radiated noise, which directly affects the noise level of the marine environment. In recent years, domestic and foreign scholars have conducted extensive research on the vibration and acoustic radiation characteristics of cylindrical shell structures. Common numerical analysis methods for structural vibration radiation noise include the finite element method, boundary element method, and unit radiation superposition method. Traditional analysis methods are complex, computationally intensive, inefficient, and lack real-time analysis capabilities. Summary of the Invention

[0003] To address the above problems, the present invention provides a parameterized underwater ribbed cylindrical shell sound radiation prediction method and system. By establishing a refined fluid-solid coupling model, it reveals the evolution law of sound radiation under multi-parameter coupling, providing technical support for low-noise structure design.

[0004] The technical solution adopted in the present invention is:

[0005] A method for predicting acoustic radiation of an underwater stiffened cylindrical shell based on parametric modeling is characterized by comprising the following steps:

[0006] Step 1: Build a parametric shell model and determine the geometric parameters, material parameters, rib parameters and fluid parameters;

[0007] Step 2: Establish vibration control equation based on Donnell-Mushtari shell theory

[0008]

[0009] in, is the bending stiffness of the shell, E is the elastic modulus of the material, h is the shell thickness, υ is the Poisson's ratio of the elastic material, w is the radial displacement of the shell, ρ S is the material density, is the overall acceleration of the shell, Nrib is the number of ribs, δ(xx j ) is a point source x j The Dirac function at I j is the section moment of inertia of the jth rib, m j is the mass per unit length (linear density) of the jth reinforcement rib, is the acceleration of the jth excitation point, p extIt is external motivational pressure;

[0010] Step 3: Use the modal superposition method to solve the frequency domain vibration response and calculate the modal amplitude using the following formula:

[0011]

[0012] Among them, F mn is the projection of the excitation force on the mode (m,n), ρ S is the shell material density, h is the shell thickness, ω is the analysis angular frequency, ω mn is the modal natural frequency, K rib is the additional stiffness of the rib, L is the axial length of the cylindrical shell, ρ W is the fluid density, a is the radius of the cylindrical shell, k is the wave number, is the second kind of Hankel function, J n is the Bessel function of the first kind, Y n is the Bessel function of the second kind;

[0013] Step 4: Calculate the sound radiation field based on the Helmholtz integral equation, and obtain the near-field sound pressure through numerical integration

[0014]

[0015] Among them, ρ W is the fluid density, ω is the analysis angular frequency, N x is the number of axial grid points, N θ is the number of circumferential grid points, v n (x i ,θ j ) is the shell (x i ,θ j ) The surface normal vibration velocity at the measuring point, k is the wave number, R ij For the measuring point (x i ,θ j ) to the shell surface element, ΔS ij is the area element;

[0016] The far-field sound pressure is obtained using the modal expansion method

[0017]

[0018] Among them, ρ W is the fluid density, c W is the speed of sound in the fluid, k is the wave number, a is the radius of the cylindrical shell, L is the axial length of the cylindrical shell, r is the observation distance of the long-distance radiation sound pressure level, Nrib is the number of ribs, ε n is the zero-order coefficient of the Bessel function, H' n is the derivative of the Hankel function, V nis the nth-order modal velocity amplitude, φ is the observation angle;

[0019] Step 5. By optimizing the structural parameters and excitation configuration, changing the shell thickness and the excitation amplitude ratio F2 / F1, observe and analyze the distribution of short-range radiation noise and the change in the main peak amplitude of the long-range radiation noise level frequency response curve, and output the spatial distribution cloud map of the short-range radiation sound pressure and the frequency response curve of the long-range radiation sound pressure level.

[0020] Preferably, the geometric parameters include shell radius a, shell length L, and shell thickness h.

[0021] Preferably, the material parameters include the material elastic modulus E, the material Poisson's ratio υ, the material density ρ s .

[0022] Preferably, the rib parameters include the number of ribs Nrib, the rib position x j , rib moment of inertia I j , rib linear density m j .

[0023] Preferably, the fluid parameters include fluid density ρ W 、Sound speed in fluid c W .

[0024] Furthermore, the system of the underwater ribbed cylindrical shell sound radiation prediction method based on parametric modeling is characterized by including a parametric modeling unit, a vibration response solver, a sound radiation calculation engine, and a visualization module.

[0025] Preferably, the parametric modeling unit is used to define shell geometry, material properties and excitation parameters.

[0026] Preferably, the vibration response solver performs a modal superposition method to calculate the vibration velocity distribution on the shell surface.

[0027] Preferably, the sound radiation calculation engine integrates the numerical integration of short-range radiation sound pressure and the modal expansion algorithm of long-range radiation noise.

[0028] Preferably, the visualization module generates a three-dimensional velocity cloud map, a sound pressure level curve and a parameter sensitivity matrix.

[0029] Compared with the existing technology, the beneficial effects of the present invention are: the calculation method of the present invention is relatively simple, the calculation amount is small, the calculation efficiency is high, the real-time analysis effect is good, the calculation speed is effectively improved, and it can provide technical support for the vibration radiation noise analysis of underwater working platforms and pipeline structures and the design of low-noise structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments or prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 This is a flow chart of the acoustic radiation prediction method for underwater stiffened cylindrical shells based on parametric modeling;

[0032] Figure 2 This is the structural diagram of the underwater ribbed cylindrical shell sound radiation prediction system based on parametric modeling;

[0033] Figure 3 : is a shell surface vibration velocity distribution diagram (900 Hz) of an embodiment of the present invention;

[0034] Figure 4 This is a three-dimensional distribution diagram of the close-range radiation sound pressure according to an embodiment of the present invention;

[0035] Figure 5 : is a close-range radiated sound pressure amplitude distribution diagram (900 Hz) of an embodiment of the present invention;

[0036] Figure 6 This is a frequency response diagram of the long-distance radiated sound pressure level according to an embodiment of the present invention;

[0037] Figure 7 This is an analysis diagram of the effect of shell thickness on long-distance radiated sound pressure level according to an embodiment of the present invention;

[0038] Figure 8 This is an analysis diagram of the effect of shell thickness on the maximum sound pressure level of long-distance radiation according to an embodiment of the present invention;

[0039] Figure 9 This is an analysis diagram of the effect of the excitation amplitude ratio F2 / F1 on the long-distance radiated sound pressure level according to one embodiment of the present invention;

[0040] Figure 10 This is an analysis diagram of the effect of the excitation amplitude ratio F2 / F1 on the maximum sound pressure level of long-distance radiation according to an embodiment of the present invention. DETAILED DESCRIPTION

[0041] In the following description, numerous specific details are provided to provide a more thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without one or more of these details. In other instances, certain technical features well known in the art are not described to avoid confusion with the present invention.

[0042] In order to fully understand the present invention, detailed steps and detailed structures will be presented in the following description to illustrate the technical solution of the present invention. Preferred embodiments of the present invention are described in detail below, but in addition to these detailed descriptions, the present invention may also have other implementations.

[0043] The flow chart of the acoustic radiation prediction method of underwater stiffened cylindrical shell based on parametric modeling is as follows Figure 1 As shown, the system based on this method is as follows Figure 2 As shown, the following steps are included:

[0044] Step 1: Input parameters, set the cylindrical shell radius a = 0.6m, cylindrical shell length L = 3m, shell thickness h = 0.02m, cylindrical shell elastic modulus E = 2×10 11 Pa, Poisson's ratio of cylindrical shell ν = 0.3, shell density ρ s =7850kg / m 3 , water density ρ W =1000kg / m 3 , the speed of sound in water c W =1500m / s, number of ribs Nrib=3, and rib spacing is 0.6m.

[0045] To simulate the vibration noise of the ribbed cylindrical shell structure, two excitation sources are set. The axial position and circumferential angle of excitation source 1 are The amplitude is 100N (Newton); the axial position and circumferential angle of the excitation source 2 are The amplitude is 50N (Newton).

[0046] Step 2: Establish the vibration control equation based on the Donnell-Mushtari shell theory, and input parameters to solve the vibration control equation.

[0047] Step 3: Use the modal superposition method to solve the frequency domain vibration response. Scanning in the range of 10-1000Hz can effectively analyze the vibration velocity distribution of the shell surface at different frequencies, such as Figure 3 Shown is the shell surface vibration velocity distribution diagram at 900Hz analysis frequency.

[0048] Step 4: Calculate the sound radiation field based on the Helmholtz integral equation, solve the close-range radiation sound pressure distribution through numerical integration, and use the modal expansion method to solve the long-range radiation sound pressure. Set the close-range radiation sound pressure observation distance to 0.6m and the long-range radiation sound pressure level observation distance to 100m. The output sound pressure level curve can effectively analyze the frequency response of the radiation noise generated by the shell structure vibration. Figure 4 The figure shows the three-dimensional distribution cloud of the close-range radiation sound pressure of the cylindrical shell at the analysis frequency of 900Hz. Figure 5The figure shows the contour map of the close-range radiated sound pressure amplitude distribution of the cylindrical shell at the analysis frequency of 900Hz. Figure 6 Shown is the frequency response graph of the long-distance radiated sound pressure level.

[0049] Step 5: Optimize the structural parameters and excitation configuration through the parameter scanning module. By changing the shell thickness, excitation amplitude ratio F2 / F1 and other parameters, the change of the main peak amplitude of the radiation noise can be effectively analyzed. Figure 7 The figure shows the effect of shell thickness on the long-distance radiation sound pressure level. Figure 8 The figure shows the effect of shell thickness on the maximum sound pressure level of long-distance radiation. Figure 9 The figure shows the effect of the excitation amplitude ratio F2 / F1 on the long-distance radiated sound pressure level. Figure 10 The figure shows the effect of the excitation amplitude ratio F2 / F1 on the maximum sound pressure level of long-distance radiation.

[0050] The acoustic radiation prediction system for underwater stiffened cylindrical shells based on parametric modeling mainly consists of several parts, including a parametric modeling unit, a vibration response solver, an acoustic radiation calculation engine, and a visualization module. The specific functions of each part are as follows:

[0051] (1) Parametric modeling unit: used to define shell geometry, material properties and excitation parameters;

[0052] (2) Vibration response solver: Executes the modal superposition method to calculate the vibration velocity distribution on the shell surface;

[0053] (3) Acoustic radiation calculation engine: Integrates the numerical integration of short-range radiation sound pressure and the modal expansion algorithm of long-range radiation noise;

[0054] (4) Visualization module: Generate three-dimensional velocity cloud map, sound pressure level curve and parameter sensitivity matrix.

[0055] The above describes the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the above-mentioned specific embodiments, and the underwater ribbed cylindrical shell sound radiation prediction method that has not been described in detail should be understood to be implemented in a common manner in the art; any technician familiar with the art can use the above-mentioned disclosed methods and technical contents to make many possible changes and modifications to the technical solutions of the present invention without departing from the scope of the technical solution of the present invention, or modify them into equivalent embodiments of equivalent changes, which does not affect the essential content of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention that do not depart from the content of the technical solution of the present invention are still within the scope of protection of the technical solution of the present invention.

Claims

1. A method for predicting acoustic radiation of underwater stiffened cylindrical shells based on parametric modeling, characterized by: The steps include: Step 1: Build a parametric shell model and determine the geometric parameters, material parameters, rib parameters and fluid parameters; Step 2: Establish vibration control equation based on Donnell-Mushtari shell theory in, is the bending stiffness of the shell, E is the elastic modulus of the material, h is the shell thickness, υ is the Poisson's ratio of the elastic material, w is the radial displacement of the shell, ρ S is the material density, is the overall acceleration of the shell, Nrib is the number of ribs, δ(xx j ) is a point source x j The Dirac function at I j is the section moment of inertia of the jth rib, m j is the mass per unit length (linear density) of the jth reinforcement rib, is the acceleration of the jth excitation point, p ext It is external motivational pressure; Step 3: Use the modal superposition method to solve the frequency domain vibration response and calculate the modal amplitude using the following formula: Among them, F mn is the projection of the excitation force on the mode (m,n), ρ S is the shell material density, h is the shell thickness, ω is the analysis angular frequency, ω mn is the modal natural frequency, K rib is the additional stiffness of the rib, L is the axial length of the cylindrical shell, ρ W is the fluid density, a is the radius of the cylindrical shell, k is the wave number, is the second kind of Hankel function, J n is the Bessel function of the first kind, Y n is the Bessel function of the second kind; Step 4: Calculate the sound radiation field based on the Helmholtz integral equation, and obtain the near-field sound pressure through numerical integration Among them, ρ W is the fluid density, ω is the analysis angular frequency, N x is the number of axial grid points, N θ is the number of circumferential grid points, v n (x i ,θ j ) is the shell (x i ,θ j ) The surface normal vibration velocity at the measuring point, k is the wave number, R ij For the measuring point (x i ,θ j ) to the shell surface element, ΔS ij is the area element; The far-field sound pressure is obtained using the modal expansion method Among them, ρ W is the fluid density, c W is the speed of sound in the fluid, k is the wave number, a is the radius of the cylindrical shell, L is the axial length of the cylindrical shell, r is the observation distance of the long-distance radiation sound pressure level, Nrib is the number of ribs, ε n is the zero-order coefficient of the Bessel function, H' n is the derivative of the Hankel function, V n is the nth-order modal velocity amplitude, φ is the observation angle; Step 5. By optimizing the structural parameters and excitation configuration, changing the shell thickness and the excitation amplitude ratio F2 / F1, observe and analyze the distribution of short-range radiation noise and the change in the main peak amplitude of the long-range radiation noise level frequency response curve, and output the spatial distribution cloud map of the short-range radiation sound pressure and the frequency response curve of the long-range radiation sound pressure level.

2. The method for predicting acoustic radiation of an underwater ribbed cylindrical shell based on parametric modeling according to claim 1, characterized in that: The geometric parameters include shell radius a, shell length L, and shell thickness h.

3. The method for predicting acoustic radiation of an underwater ribbed cylindrical shell based on parametric modeling according to claim 1, characterized in that: The material parameters include material elastic modulus E, material Poisson's ratio υ, material density ρ s .

4. The method for predicting acoustic radiation of an underwater ribbed cylindrical shell based on parametric modeling according to claim 1, characterized in that: The rib parameters include the number of ribs Nrib, the rib position x j , rib moment of inertia I j , rib linear density m j .

5. The method for predicting acoustic radiation of an underwater ribbed cylindrical shell based on parameterized modeling according to claim 1, wherein: The fluid parameters include fluid density ρ W 、Sound speed in fluid c W .

6. A system based on the method for predicting acoustic radiation of an underwater stiffened cylindrical shell based on parameterized modeling according to any one of claims 1 to 5, characterized in that: It includes parametric modeling unit, vibration response solver, sound radiation calculation engine, and visualization module.

7. The system according to claim 6, wherein: The parametric modeling unit is used to define the shell geometry, material properties and excitation parameters.

8. The system according to claim 6, wherein: The vibration response solver performs a modal superposition method to calculate the vibration velocity distribution on the shell surface.

9. The system according to claim 6, wherein: The sound radiation calculation engine integrates the numerical integration of short-range radiation sound pressure and the modal expansion algorithm of long-range radiation noise.

10. The system according to claim 6, wherein: The visualization module generates a three-dimensional velocity cloud map, a sound pressure level curve, and a parameter sensitivity matrix.

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