A wind-assisted rotor out-field vibration sound radiation simulation method

Abstract

The present application relates to a kind of wind power boost rotor field vibration sound radiation simulation method, based on fluid simulation software Star-ccm+, with wind power boost rotor outer tube profile as rigid wall, set the inlet condition as wind speed, outlet condition speed is 0, calculate the fluctuating pressure of outer tube profile;Based on structural finite element software Abaqus, according to the finite element model of wind power boost rotor outer tube structure, with fluctuating pressure as load input, and constraint condition is added, the vibration displacement of outer tube is calculated;Based on acoustic finite element software Actran, import the node position information of structural finite element model, establish the field acoustics domain, with the vibration displacement of outer tube as load input, calculate the field vibration sound radiation of outer tube;The method is based on frequency domain to carry out calculation, cannot reflect the real sound wave transmission and actual sound pressure size, with certain limitation.Therefore the present application adopts vibration sound radiation time domain simulation analysis method, can obtain vibration sound radiation in time domain, and obtain the actual sound pressure variation with time.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wind-assisted rotor technology, in particular to a wind-assisted rotor outfield vibration sound radiation simulation method. BACKGROUND

[0002] The wind-assisted rotor utilizes wind energy to assist ship navigation, is a structure-independent, simple-to-install, and innovative energy-saving technology with good prospects. Foreign application shows that the energy-saving effect of wind-assisted rotor for bulk carriers and large oil tankers can reach 5%-30%, which is an important technical means to solve EEDI phase 3. The ship equipped with wind-assisted rotor can produce forward thrust by adjusting the speed and direction of the rotor in crosswind or diagonal wind state, thereby achieving the effect of wind energy assistance. Compared with the wind-assisted technology such as kites and sails, the wind-assisted rotor has strong adaptability to wind speed and direction, relatively small volume and wind area, is safer, and is more conducive to ship arrangement. In addition, the wind-assisted rotor and other energy-saving and emission-reducing means such as water power energy-saving and alternative fuel can be used together to further enhance the energy-saving and emission-reducing effect, and are suitable for new ships and operating ships.

[0003] Through research, it is found that during the operation of the wind-assisted rotor, due to the high-speed rotation of the outer cylinder, the flexibility of the system itself, and the impact of the internal equipment, structural vibration will occur and a large amount of noise will be generated, especially after the wind-assisted rotor is installed on the ship, the vibration response will be greater. The dynamic load generated by the vibration of the wind-assisted rotor is positively correlated with the weight, so once the large wind-assisted rotor still has such a large vibration amount, the dynamic load generated by the vibration will inevitably threaten the safety of the structure. Therefore, it is necessary to simulate and predict the noise of the wind-assisted rotor during operation. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a wind-assisted rotor outfield vibration sound radiation simulation method which can simulate the noise of the wind-assisted rotor during operation.

[0005] The technical problem to be solved by the present application is solved by the following technical scheme, a wind-assisted rotor outfield vibration sound radiation simulation method, comprising the following steps:

[0006] (1) using the fluid simulation software Star-ccm+ to establish the external contour model of the wind-assisted rotor, and setting the fluid domain, wherein the inlet condition is wind speed, the outlet condition is pressure outlet, and the rest of the surfaces are set as no-slip wall surfaces, the external contour of the wind-assisted rotor is set as a wall surface and the relative rotation rate of the wall surface is given;

[0007] (2) The grid of the outer contour of the wind-assisted rotor is encrypted, the detached flow fluid model is selected, the gas is set as constant density, the K-Omega turbulence model is adopted to perform unsteady calculation, and the fluctuating pressure data of the grid points on the outer cylinder part of the wind-assisted rotor are obtained;

[0008] (3) The fluctuating pressure data output by Star-ccm+ are mapped to the structural grid form through grid mapping technology, and are exported as node files and load files, wherein the grid mapping technology includes dividing the outer cylinder contour into small areas, and mapping the fluid grid of each area to a single grid point;

[0009] (4) In the Abaqus finite element analysis software, a finite element model is constructed according to the geometric model of the wind-assisted rotor, the secondary development function is used to read and bind the reference points established through the node files and load files to the outer cylinder contour geometric model in a loop, and the fluctuating pressure loading is realized;

[0010] (5) In Abaqus, the dynamic implicit analysis method is adopted, the maximum increment step is set as 0.1s to ensure the stability and accuracy of subsequent acoustic simulation calculation, the dynamic analysis is carried out, and the normal vibration response of the outer cylinder of the wind-assisted rotor is obtained;

[0011] (6) The calculation results of Abaqus are imported into the acoustic finite element software Actran to obtain an acoustic structure model, an acoustic model outer envelope surface is obtained based on the acoustic structure model, and an outer acoustic field is generated based on the outer envelope surface;

[0012] (7) In Actran, the acoustic boundary condition is set as the non-reflective boundary Infinite, the sound wave is simulated to not reflect at the boundary, a suitable interpolation order Interpolation Order is set, and the normal vibration response obtained by Abaqus calculation is imported as the acoustic excitation boundary condition;

[0013] The setting of the non-reflective boundary Infinite boundary condition aims to simulate the free propagation of sound waves in an infinite acoustic field, and avoid the calculation deviation of sound pressure caused by boundary reflection;

[0014] (8) Time-domain acoustic vibration and sound radiation analysis is carried out in Actran, the sound pressure of each point in the outer acoustic domain is calculated, the overall transmission and variation trend of the sound pressure can be obtained, and the sound pressure variation and actual sound pressure size at the concerned position can also be obtained;

[0015] The time-domain acoustic analysis can accurately reflect the real situation of sound wave transmission and the actual sound pressure size, and provide detailed information of vibration sound radiation in the time domain and the variation of sound pressure with time.

[0016] The technical problems to be solved by the present application can also be realized by the following technical solutions, the wind power boosting rotor external field vibration sound radiation simulation method described above, in step (3), the grid mapping method includes dividing the wind power boosting rotor outer cylinder contour into small areas, and mapping the fluid grid in each area to a grid point, so as to reduce the number of grids and optimize the calculation resources and efficiency.

[0017] The technical problems to be solved by the present application can also be realized by the following technical solutions, the wind power boosting rotor external field vibration sound radiation simulation method described above, in step (4), the specific steps are as follows:

[0018] (4.1) establishing a finite element model based on the wind power boosting rotor geometric model;

[0019] (4.2) based on the node file obtained in step (3), traversing the node file, reading by line, creating a reference point in abaqus every time a line of coordinates is read, thereby obtaining a set of structure loading grid, and binding all reference points with the outer cylinder contour geometric model, so that the load can be transmitted to the outer cylinder structure;

[0020] (4.3) based on the load file obtained in step (3), traversing the load file, reading by line, creating a load amplitude curve every time a line of time-varying load is read;

[0021] (4.4) based on the reference points of step (4.2) and the load amplitude curve of step (4.3), creating a load in batch, the load action area is the reference point, the load size is 1, and the load amplitude is the load amplitude curve, finally completing the loading work of the fluctuating pressure.

[0022] The technical problems to be solved by the present application can also be realized by the following technical solutions, the wind power boosting rotor external field vibration sound radiation simulation method described above, in step (7), the setting of the Infinite boundary condition without reflection boundary is used to simulate the propagation process of sound waves in an infinite sound field, to avoid the calculation result of sound pressure being too large due to the reflection of sound waves on the boundary, the setting of this value is closely related to the size of the acoustic domain, when the acoustic domain is small, a larger interpolation order Interpolation Order needs to be set, otherwise when the acoustic domain is large, a smaller interpolation order Interpolation Order needs to be set.

[0023] The technical problems to be solved by the present application can also be realized by the following technical solutions, the wind power boosting rotor external field vibration sound radiation simulation method described above, in step (8), the time domain acoustic analysis can reflect the real sound wave transmission and the actual sound pressure, and obtain the vibration sound radiation in the time domain and the actual sound pressure changing with time.

[0024] Compared with the prior art, the beneficial technical effect of the present application is that the method is based on frequency domain to carry out calculation, which cannot reflect the real sound wave transmission and the actual sound pressure size, and has certain limitations. Therefore, the vibration sound radiation time domain simulation analysis method is adopted in the present application, the vibration sound radiation in the time domain can be obtained, and the actual sound pressure changes with time; in addition, the method realizes the accurate simulation of the wind power boosting rotor outer field vibration sound radiation by combining the fluid simulation software Star-ccm+, the finite element analysis software Abaqus and the acoustic finite element software Actran, especially by encrypting the outer contour grid, selecting the separated flow fluid model and adopting the K-Omega turbulence model to perform unsteady calculation, the fluctuating pressure data on the outer contour grid points of the wind power boosting rotor outer cylinder part can be accurately obtained, thereby improving the simulation accuracy. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The simulation flowchart of the wind power boosting rotor outer field vibration sound radiation simulation method of the present application is shown in the figure.

[0026] Figure 2 The fluid simulation diagram of the wind power boosting rotor outer field vibration sound radiation simulation method of the present application is shown in the figure.

[0027] Figure 3 The fluid domain velocity distribution diagram of the wind power boosting rotor outer field vibration sound radiation simulation method of the present application is shown in the figure.

[0028] Figure 4 The network mapping flowchart of the wind power boosting rotor outer field vibration sound radiation simulation method of the present application is shown in the figure.

[0029] Figure 5 The load loading flowchart of the wind power boosting rotor outer field vibration sound radiation simulation method of the present application is shown in the figure.

[0030] Figure 6 The normal vibration response schematic diagram of the wind power boosting rotor outer cylinder of the wind power boosting rotor outer field vibration sound radiation simulation method of the present application is shown in the figure.

[0031] Figure 7 The acoustic simulation flowchart of the wind power boosting rotor outer field vibration sound radiation simulation method of the present application is shown in the figure. DETAILED DESCRIPTION

[0032] The specific technical solutions of the present application are further described below with reference to the accompanying drawings, so as to further understand the present application by those skilled in the art without limiting the rights thereof.

[0033] Embodiment 1, refer to Figures 1-7 A wind power boosting rotor outer field vibration sound radiation simulation method, the main idea of the method is:

[0034] (1) Based on the fluid simulation software Star-ccm+, the outer tube contour of the wind-assisted rotor is set as a rigid wall, and the inlet condition is set as wind speed and the outlet condition is set as 0. The fluctuating pressure of the outer tube contour is calculated;

[0035] (2) Based on the structural finite element software Abaqus, a finite element model is established according to the structure of the wind-assisted rotor outer tube. The fluctuating pressure is input as the load and the constraint condition is added. The vibration displacement of the outer tube is calculated;

[0036] (3) Based on the acoustic finite element software Actran, the node position information of the structural finite element model is imported. The outer field acoustic domain is established with the vibration displacement of the outer tube as the load input. The outer field vibration sound radiation of the outer tube is calculated.

[0037] In addition, we mean the outer field as the outer acoustic field. For example, a hollow sphere, its interior is the inner acoustic field, and the exterior is the outer acoustic field. If the inner acoustic field is calculated, the steps are the same, and the internal fluid domain can be established. The only difference is that the reflection of sound waves on the structure wall should be considered when calculating the inner acoustic field. Therefore, the inside and outside are the inside and outside in terms of spatial position. Because we are concerned about the sound heard outside when the rotor is running, that is, the noise radiated by the rotor, that is, this is to solve the vibration of the outer field;

[0038] In addition, the fluid domain is a rectangle.

[0039] The specific process is as follows:

[0040] I. About fluid simulation:

[0041] 1. According to the geometric model of the wind-assisted rotor, the outer contour model is established in starccm+, and a rectangular fluid domain is established outside;

[0042] 2. Set the inlet, outlet and wall conditions respectively:

[0043] 2.1 The inlet condition is velocity inlet, and the initial velocity of the fluid is given;

[0044] 2.2 The outlet condition is pressure outlet;

[0045] 2.3 The rest of the fluid domain is set as no-slip wall, which means that the velocity of the fluid at the wall is zero;

[0046] 2.4 The outer contour of the wind-assisted rotor is set as a wall, and the relative rotation rate of the wall is given to simulate its rotation in the fluid domain. It should be noted that the given wall relative rotation rate is loaded according to the actual speed of the wind-assisted rotor;

[0047] 3, The grid of the outer contour of the wind-assisted rotor is encrypted to ensure the accuracy of the calculation results. It should be noted that this encryption process is actually to set the grid size of the area close to the structure to be smaller. Because finite element calculation is grid calculation, one grid and ten grids are definitely not the same. One grid is a value, but ten grids can show the changes in this small area, and the results will be more accurate and less likely to miss some peaks. Since we mainly focus on the flow field changes around the structure, encryption is needed, and the grid farther away does not need to be concerned, so it can be slightly larger in size to optimize the calculation efficiency. The specific value can be selected according to the user's needs;

[0048] 4, Select a separated flow fluid, set the gas density to be constant, and use the K-Omega turbulence model to carry out unsteady calculation. It should be noted that this unsteady calculation is based on time. According to whether the physical quantities of the fluid (such as velocity, pressure, temperature, etc.) change with time, the flow can be divided into two categories: unsteady flow and non-unsteady flow. If the physical quantities of the fluid do not change with time, it is non-unsteady flow. If the physical quantities of the fluid change with time, it is called unsteady flow.

[0049] 5, Set the output condition to output the fluctuating pressure at the grid points on the outer contour of the wind-assisted rotor.

[0050] II. Network mapping, refer to Figure 4 :

[0051] 1, Based on the star-ccm+ simulation software, output the node pressure on the outer contour of the wind-assisted rotor into a csv file:

[0052] 1.1 Output into 1 csv file at each time, a total of 300 files, with a time interval of 0.2s, a total of 60s;

[0053] 1.2 In each csv file, the first column of data is the fluctuating pressure at the current time, and the second, third, and fourth columns are the x, y, and z coordinates. Each csv file has 25834 nodes.

[0054] Due to the large number of fluid grids, if all are imported into the structure model for calculation, it will require huge computing resources and seriously affect the calculation efficiency, so it is necessary to perform grid mapping. The fluid grid is reduced in number by grid mapping method and output as a set of structure grid;

[0055] 2, Simplified principle of grid mapping:

[0056] 2.1 The outer contour of the wind-assisted rotor is composed of a cylinder and a top cover. The fluid grid of the cylinder and the top cover is mapped respectively.

[0057] 2.2 The operation of the specific mesh mapping is to divide the outer cylinder contour into small areas, and the fluid mesh in each area is mapped to one mesh point, so as to reduce the number of meshes. It should be noted that, here,

[0058] 2.3 Since the outer cylinder of the wind-assisted rotor is a cylinder, the cylindrical coordinate system is used for mesh mapping when mesh mapping is performed, and the coordinate origin is taken at the center of the bottom of the outer cylinder, and the height direction of the outer cylinder is the Z axis;

[0059] 3. Mesh mapping process:

[0060] 3.1 According to the parameters of the wind-assisted rotor, the parameters of the cylinder and the top cover are determined;

[0061] 3.2 The number of cylinder distribution along the axis and the number of top cover distribution along the radial direction and the circumferential direction are set independently;

[0062] 3.3 The cylinder and the top cover are divided along the axial direction, the circumferential direction and the radial direction to determine the loading area of the cylinder / top cover and the cylindrical coordinates of the center loading point of each loading area;

[0063] 3.4 Coordinate system conversion is carried out to convert the cylindrical coordinate system into the rectangular coordinate system to obtain the area of each loading area and the rectangular coordinates of the center loading point;

[0064] 3.5 Based on the fluctuating pressure of the outer cylinder contour calculated by star-ccm+ (i.e. the above-mentioned csv file), the coordinates of the fluid mesh point and the fluctuating pressure at each point varying with time are known;

[0065] 3.6 Traverse the fluid mesh coordinate point, determine the loading area where the coordinate point is located based on the loading area obtained in 3.3, count and accumulate the fluctuating pressure to obtain the number of fluid mesh points contained in each area and the total sum of the fluctuating pressure, and finally obtain the average pressure of each area;

[0066] 3.7 Based on the loading area obtained in 3.4 and the average pressure of each area obtained in 3.6, the loading load of each area is obtained;

[0067] 3.8 Based on the loading point coordinates in 3.4 and the loading point load in 3.7, the structure mesh after mesh mapping of the fluid mesh (including mesh coordinates and load of each mesh point varying with time) is obtained;

[0068] 4. Load output:

[0069] 4.1 The structure mesh obtained above is output into two files of node file and load file;

[0070] 4.11 Node file: each line is a different mesh point, and the columns are x, y, z coordinates;

[0071] 4.12 Load file: each line is a different grid point, column is the load along time;

[0072] 5, Load loading, refer to Figure 5 :

[0073] 5.1 Based on Abaqus large finite element analysis software, secondary development operation, read the node file and load file in a cycle, batch load fluctuating pressure on the outer cylinder contour geometry model, the specific process is as follows:

[0074] 5.11 Based on the wind-assisted rotor model, the wind-assisted rotor geometry model (including the outer cylinder contour geometry model) is established in the abaqus software;

[0075] 5.12 Based on the node file obtained in the previous step, traverse the node file, read by line, read a line of coordinates, create a reference point in abaqus, and get a set of structure loading grid, and bind all reference points with the outer cylinder contour geometry model, so that the load can be transmitted to the outer cylinder structure;

[0076] It should be noted that the load can be transmitted to the outer cylinder structure, the load needs to input three direction values CF1, CF2, CF3, and then give an amplitude curve, the final load is CFx amplitude, such as CF is (0, 0, 2), which is the load in z direction, the size is 2 times the amplitude curve, the time change is the output of the fluid, the step length of the fluid output is large, then the step length of the load is large, the total length of the fluid calculation is large, then the length of the load is large;

[0077] It should be noted that the reference point is the name of the abaqus software, which is not a proper noun. Its actual meaning is to create a spatial geometry point according to its xyz coordinates;

[0078] In addition, the above-mentioned binding is actually an operation of the abaqus software, which belongs to the general term of structure finite element calculation. Its meaning is to control the consistency of the 6 degrees of freedom of the nodes at the contact point of the two parties, and no relative displacement and rotation angle (6 degrees of freedom are U1, U2, U3, UR1, UR2, UR3, that is, xyz direction displacement and rotation angle) occurs. It also sets a distance tolerance, so when some involve surface binding, even if the geometric position is not necessarily coincident, it can also be automatically corrected to the corresponding position according to this tolerance, so that the load is loaded on the above-mentioned spatial geometry point, which is equivalent to directly loaded on the corresponding position of the structure;

[0079] 5.13 Based on the load file obtained in the previous step, traverse the load file, read by line, and create a load amplitude curve for each line of time-varying load. Note that the creation of the load amplitude curve is based on the software's built-in functions and secondary development. When loading, you need to input a load value and its change curve. This change curve has two columns: the first column is time, and the second column is load size. Both need to be manually input. If you only use the software, you need to manually input the load. The workload is unimaginable, but based on secondary development, you can use the program to batch read input. The specific program content can be selected according to the use requirements;

[0080] 5.14 Based on the reference point of 5.12 and the load amplitude curve of 5.13, batch create loads, the load action area is the reference point, the load size is 1, and the load amplitude is the load amplitude curve. Finally, complete the loading work of the pulsating pressure.

[0081] Three, structure simulation:

[0082] 1. Based on the Solidworks three-dimensional model of the wind-assisted rotor, complete the two-dimensional CAD schematic diagram of each part of the wind-assisted rotor outer cylinder;

[0083] 2. Based on the two-dimensional CAD schematic diagram and size marking of each part of the outer cylinder, establish the finite element model of the outer cylinder in the large-scale finite element analysis and calculation software Abaqus;

[0084] 3. Use dynamic implicit analysis method to carry out dynamic calculation, and set the maximum incremental step to 0.1s for subsequent acoustic simulation calculation. Note that the dynamic implicit analysis method here is an analysis method that needs to be set during calculation. Generally, it is divided into static calculation and dynamic calculation, and dynamic explicit calculation and dynamic implicit calculation are divided in dynamic calculation. We use dynamic implicit because our model involves multiple load points, which involves complex freedom problems. Therefore, the implicit analysis has better calculation precision and is easier to converge;

[0085] 4. Normal vibration response of wind-assisted rotor outer cylinder, refer to Figure 6 The maximum normal vibration response is at the edge of the top cover.

[0086] Four, acoustic simulation, refer to Figure 7 :

[0087] 1. Acoustic simulation model:

[0088] 1.1 The outer envelope surface of the wind-assisted rotor acoustic model: based on the Abaqus calculation results, import them into the actran software, and generate the outer envelope surface based on the model;

[0089] 1.2 Acoustic domain: Based on the outer envelope surface, the outer acoustic field domain is generated by using the "radiation" method;

[0090] 1.3 Acoustic domain boundary: The acoustic field domain boundary is generated at the same time when the outer acoustic field domain is generated based on step 1.2, and the acoustic boundary condition is given;

[0091] 1.4 Field point: 12 field points are uniformly arranged on the circumference of a circle with a radius of 12.5 m and a height of 2 m;

[0092] 2. Acoustic simulation process:

[0093] 2.1 Based on the simulation results of the structure finite element, the structure grid node information and grid node vibration are obtained;

[0094] 2.2 The structure grid node information is imported into the actran software to obtain the acoustic structure model;

[0095] 2.3 Based on this model, the outer envelope surface of the acoustic model is generated, and the grid node vibration information is imported into actran as the acoustic excitation boundary of the outer envelope surface, so as to calculate the vibration sound radiation;

[0096] 2.4 Based on the outer envelope surface formed in step 2.3, the outer acoustic domain is generated by using the "radiation" method. The acoustic model outer envelope surface and the acoustic domain are coupled with each other. Based on the vibration sound radiation principle, sound waves are generated at the coupling boundary through acoustic excitation (i.e. normal vibration). Based on the transmission principle of sound waves in the fluid domain (sound radiation principle), the sound pressure of each point in the acoustic domain can be calculated;

[0097] 2.5 Based on the "radiation" of step 2.4, the outer acoustic domain boundary is generated. Since the acoustic domain in the actual situation is an infinite region, it is impossible to establish an infinite acoustic domain in the acoustic simulation, so it is necessary to set the acoustic domain boundary to simulate an infinite sound field domain. Otherwise, when the sound wave is transmitted to the boundary, reflection will occur, resulting in an overestimated sound pressure result;

[0098] It should be noted that the meaning of "infinite" here is that the sound wave is radiated without reflection. Of course, this is an ideal situation. After all, sound waves will reflect off objects. However, one is that the sound wave will attenuate with propagation, and the other is that the direction after reflection may not return to the sound field to affect the noise level. Therefore, as long as the structure is in an open area, it can be simulated as an infinite sound field domain by this method;

[0099] 2.6 Set the acoustic boundary in actran mainly has no reflection boundary Infinite, PML, APML, Exterior method, here select no reflection boundary Infinite method, need to note that, the no reflection boundary Infinite method here involves a sound transmission theory, such as a wall, two hundred years is air, when the sound wave from air into the wall, because of the impedance (the density, elastic modulus, poisson's ratio of the wall, etc. Related) reason, only a part of the sound wave can be penetrated, another part is refracted back, and then from the wall to penetrate the air again loss a part, the sound wave that penetrates the air is the sound transmission coefficient of the wall, however, the principle of no reflection is to set the impedance to achieve the principle of complete absorption of sound wave without reflection, simulate it in air infinite propagation, no sound wave reflection back, this method simulates the sound wave at the boundary without reflection by setting the acoustic domain boundary to no reflection boundary, so as to achieve the process of simulating the sound wave in the acoustic domain infinite propagation;

[0100] 2.7 In the no reflection boundary Infinite setting, interpolation order Interpolation Order needs to be set, the value of this setting is closely related to the size of the acoustic domain, when the acoustic domain is small, a larger interpolation order Interpolation Order needs to be set, otherwise when the acoustic domain is large, a smaller interpolation order Interpolation Order is also possible;

[0101] It should be noted that the size of the interpolation order is related to the size of the sound field domain and the wavelength, when the sound field domain thickness is small and the wavelength is large, a higher interpolation order is needed, when the sound field domain thickness is large and the wavelength is small, a smaller interpolation order is needed, which can be tested by a finite number of times to analyze the convergence, and a suitable interpolation order that can meet the accuracy and efficiency can be obtained by taking different interpolation orders to see the convergence of the results;

[0102] 2.8 After setting the sound field domain, the no reflection boundary Infinite and the acoustic excitation boundary condition, time domain sound vibration and sound radiation analysis can be carried out;

[0103] It should be noted that:

[0104] The common frequency domain acoustic analysis process is: calculate the time domain fluctuating pressure through fluid simulation software, convert the fluctuating pressure from time domain to frequency domain load through Fourier transform, load the frequency domain fluctuating pressure on the structure to carry out frequency response calculation, and get the vibration response of the structure at each frequency point; Finally, the response is imported into the acoustic software as the acoustic excitation to carry out vibration sound radiation simulation calculation; This method is based on frequency domain calculation, which cannot reflect the real sound wave transmission and the actual sound pressure, and has certain limitations.

[0105] Therefore, the present application adopts the vibration sound radiation time domain simulation analysis method, so that the vibration sound radiation in the time domain can be obtained, and the actual sound pressure change with time can be obtained;

[0106] In addition, the time domain acoustic analysis is based on the time domain acoustic simulation calculation, and the acoustic excitation boundary condition loaded by the time domain acoustic analysis is the time normal vibration response calculated by the finite element software Abaqus directly, the vibration sound radiation simulation calculation is carried out through the set increment step, the sound pressure in the acoustic domain is calculated, the sound pressure change with time at the field point is calculated through the sound radiation principle, the sound pressure overall transmission and change trend can be obtained, and the sound pressure change and actual sound pressure size at the concerned position can be obtained;

[0107] It should be noted that, since the analysis object has structural simplicity, that is, it presents a regular cylindrical shape, its sound wave radiation mode presents a typical ring-shaped diffusion characteristic, and uniformly propagates outward along the circumference, therefore, by observing the sound wave propagation path and intensity distribution, the sound wave radiation strong area and how the sound wave dynamically changes with the structure morphology can be directly identified, such analysis helps us to accurately judge the potential acoustic weakness in the structure, and then guide to take targeted optimization measures, such as adding damping materials in the area where the sound wave radiation is significant, so as to realize the improvement of the acoustic performance.

Claims

1. A wind-assisted rotor out-of-field vibration acoustic radiation simulation method, characterized in that, Comprise the following steps: (1) using fluid simulation software Star-ccm+ to establish the wind boost rotor external contour model, and set the fluid domain, wherein the inlet condition is wind speed, the outlet condition is pressure outlet, the rest of the surface is set as no slip wall, the wind boost rotor external contour is set as wall and the wall relative rotation rate is given; (2) the grid of the wind boost rotor external contour is encrypted, the separated flow fluid model is selected, the gas is set as constant density, the K-Omega turbulence model is adopted to execute the unsteady calculation, so as to obtain the fluctuating pressure data of the wind boost rotor external cylinder part contour grid point; (3) through the grid mapping technology, the fluctuating pressure data output by Star-ccm+ is mapped to the structure grid form, and is exported as node file and load file, wherein the grid mapping technology comprises dividing the external cylinder contour into small areas, and mapping the fluid grid in each area to a single grid point; (4) in Abaqus finite element analysis software, the finite element model is constructed according to the wind boost rotor geometric model, the secondary development function is used to cyclically read and bind the reference points established through the node file and the load file to the external cylinder contour geometric model, so as to realize the loading of fluctuating pressure; (5) in Abaqus, the dynamic implicit analysis method is adopted, the maximum increment step is set as 0.1s, the dynamic analysis is carried out, and the normal vibration response of the wind boost rotor external cylinder is obtained; (6) the calculation results of Abaqus are imported into the acoustic finite element software Actran, the acoustic structure model is obtained, the acoustic model outer envelope surface is obtained based on the acoustic structure model, and the outer acoustic field domain is generated based on the outer envelope surface; (7) in Actran, the acoustic boundary condition is set as non-reflection boundary Infinite, the reflection of sound wave at the boundary is simulated, the appropriate interpolation order Interpolation Order is set, and the normal vibration response obtained by Abaqus calculation is imported as the acoustic excitation boundary condition; (8) in Actran, the time domain acoustic vibration and acoustic radiation analysis is carried out, the sound pressure of each point in the outer acoustic domain is calculated, the overall transmission and variation trend of sound pressure can be obtained, and the sound pressure variation and actual sound pressure size at the concerned position can also be obtained.

2. The wind-boosted rotor out-of-field vibration acoustic radiation simulation method of claim 1, wherein: In step (3), the grid mapping method comprises dividing the wind boost rotor external cylinder contour into small areas, and mapping the fluid grid in each area to a grid point, so as to reduce the number of grids and optimize the calculation resources and efficiency.

3. The wind-boosted rotor out-of-field vibration acoustic radiation simulation method of claim 1, wherein, In step (4), the specific steps are as follows: (4.1) based on the wind boost rotor geometric model, a finite element model is established; (4.2) based on the node file obtained in step (3), the node file is traversed, a reference point is created in Abaqus for each row of coordinates read, so that a set of structure loading grids are obtained, and all reference points are bound to the external cylinder contour geometric model, so that the load can be transmitted to the external cylinder structure; (4.3) based on the load file obtained in step (3), the load file is traversed, a load amplitude curve is created for each row of time-varying load read; (4.4) Based on the reference point of step (4.2) and the load amplitude curve of step (4.3), a load is created in batches, the load acting area is the reference point, the load size is 1, and the load amplitude is the load amplitude curve, and finally the loading work of the pulsating pressure is completed.

4. The wind-boosted rotor out-of-field vibration acoustic radiation simulation method of claim 1, wherein: In step (7), the setting of the non-reflective boundary Infinite boundary condition is used to simulate the propagation process of sound waves in an infinite sound field domain, avoiding the calculation of sound pressure being too large due to the reflection of sound waves on the boundary. The setting of this value is closely related to the size of the acoustic domain. When the acoustic domain is small, a larger interpolation order Interpolation Order needs to be set. Conversely, when the acoustic domain is large, a smaller interpolation order Interpolation Order needs to be set.

5. The wind-boosted rotor out-of-field vibration acoustic radiation simulation method of claim 1, wherein: In step (8), time-domain acoustic analysis can reflect the real sound wave transmission and the actual sound pressure size, and obtain the vibration sound radiation in the time domain and the actual sound pressure change with time.

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