Helicopter three-dimensional sound field prediction method, device, equipment, medium and product

Abstract

The invention discloses a helicopter three-dimensional sound field prediction method and device, equipment, a medium and a product, and relates to the field of helicopter aeroacoustics, and the method comprises the steps: obtaining observation point information, and extracting flight parameters on a flight path of a helicopter; carrying out selection and attitude alignment on the flight parameters on the flight path of the helicopter and radiation balls in a helicopter sound radiation ball library to obtain the radiation balls corresponding to the flight path; the helicopter sound radiation ball library is constructed by using load information of a helicopter; taking a radiation ball corresponding to the flight path as a sound source for radiation, and calculating sound pressure levels of observation points under different propagation paths according to the observation point information based on a Gaussian beam theory of fluctuation acoustics; determining a total sound pressure level based on atmospheric sound absorption, geometric attenuation and reflection / transmission attenuation according to the sound pressure levels of the observation points in different propagation paths; and generating a helicopter three-dimensional sound field cloud picture by using the total sound pressure level. According to the method, the three-dimensional sound field of the helicopter under the complex terrain can be quickly predicted.

Description

Technical Field

[0001] This application relates to the field of helicopter aeroacoustics, and in particular to a method, apparatus, equipment, medium and product for predicting the three-dimensional sound field of a helicopter. Background Technology

[0002] Rapid prediction technology for the three-dimensional sound field of helicopters in complex terrain can predict the intensity of flight noise in the background environment before a flight mission, which is of great help for special helicopter flight missions. At the same time, the lower flight noise also meets the daily requirements of urban residents. Therefore, rapid prediction technology for the three-dimensional sound field of helicopters in complex terrain is of great significance to the development and use of helicopters. Summary of the Invention

[0003] The purpose of this application is to provide a method, apparatus, equipment, medium, and product for predicting the three-dimensional sound field of a helicopter, which can quickly predict the three-dimensional sound field of a helicopter under complex terrain.

[0004] To achieve the above objectives, this application provides the following solution:

[0005] In a first aspect, this application provides a method for predicting the three-dimensional sound field of a helicopter, including:

[0006] Acquire observation point information and extract flight parameters from the helicopter's flight path;

[0007] The flight parameters on the helicopter's flight trajectory are selected and their attitudes aligned with the radiation spheres in the helicopter acoustic radiation sphere library to obtain the radiation sphere corresponding to the flight trajectory; the helicopter acoustic radiation sphere library is constructed using the helicopter's payload information;

[0008] The radiation sphere corresponding to the flight trajectory is used as a sound source for radiation. Based on the Gaussian beam theory of wave acoustics, the sound pressure level of the observation point is calculated under different propagation paths according to the observation point information.

[0009] The total sound pressure level is determined based on atmospheric absorption, geometric attenuation, and reflection / transmission attenuation at the observation points under different propagation paths.

[0010] A three-dimensional sound field cloud map of a helicopter is generated using the total sound pressure level.

[0011] In one embodiment, the flight parameters along the helicopter's flight trajectory are selected and their attitudes aligned with radiation spheres in a helicopter acoustic radiation sphere library to obtain a radiation sphere corresponding to the flight trajectory. Specifically, this includes:

[0012] The flight noise characteristic parameters of the radiation spheres in the helicopter acoustic radiation sphere library are used as interpolation parameters. The flight parameters on the helicopter flight trajectory are used as the target points for interpolation calculation to obtain the corresponding acoustic radiation spheres.

[0013] The corresponding acoustic radiation sphere is rotated based on the flight parameters on the flight trajectory to obtain the radiation sphere corresponding to the flight trajectory.

[0014] In one embodiment, the construction process of the helicopter acoustic radiation sphere specifically includes:

[0015] The range of characteristic parameters of the helicopter's acoustic radiation sphere during flight noise is determined based on the helicopter's configuration.

[0016] Based on the range of characteristic parameters of the helicopter's acoustic radiation sphere during flight noise, unsteady aerodynamic calculation methods are used to obtain the load information of the helicopter under different flight noise characteristic parameters.

[0017] The acoustic radiation sphere of a helicopter is calculated based on the helicopter aerodynamic noise calculation method using load information of the helicopter under different flight noise characteristic parameters.

[0018] Construct a helicopter acoustic radiation sphere library based on the aforementioned helicopter acoustic radiation sphere library.

[0019] In one embodiment, a radiating sphere corresponding to the flight trajectory is used as a sound source for radiation. Based on the observation point information and Gaussian beamforming theory of wave acoustics, the sound pressure level at the observation point under different propagation paths is calculated. Specifically, this includes:

[0020] The radiating sphere corresponding to the flight trajectory is used as a sound source for radiation.

[0021] The propagation path of the direct sound is determined based on the observation point information and the sound source, and the sound pressure level at the observation point under the direct sound path is determined by the relative direction vector based on the propagation path of the direct sound.

[0022] Determine the direction vectors of the observation point and the sound source based on the observation point information and the sound source;

[0023] The propagation path of the transmitted sound is determined based on the normal vector of the environmental grid surface and the direction vectors of the observation point and the sound source, and the sound pressure level at the observation point under the transmission path is determined based on the propagation path of the transmitted sound and the observation point information.

[0024] Divide the radiation sphere corresponding to the flight trajectory into equal areas and generate propagation rays;

[0025] The ray path is determined based on the observation point information and the forward sound propagation calculation method of the propagating ray, and the sound pressure level of the observation point under the reflection path is determined based on the Gaussian beam theory of wave acoustics according to the ray path.

[0026] In one embodiment, the total sound pressure level is determined based on atmospheric absorption, geometric attenuation, and reflection / transmission attenuation at the observation point under different propagation paths, specifically including:

[0027] The sound pressure level of the direct sound wave is determined based on the sound pressure level at the observation point under the direct path and the sound pressure level at the observation point under the transmission path, taking into account atmospheric sound absorption effect, transmission attenuation loss and geometric loss.

[0028] The sound pressure level of the reflected sound wave is determined based on the sound pressure level at the observation point under the reflection path, taking into account atmospheric sound absorption effect, reflection attenuation loss, and geometric loss.

[0029] The total sound pressure level is obtained by summing the direct sound wave sound pressure level and the reflected sound wave sound pressure level.

[0030] In one embodiment, generating a three-dimensional sound field cloud map of the helicopter using the total sound pressure level specifically includes:

[0031] The total sound pressure level is summarized according to the time information to obtain a sound pressure level cloud map;

[0032] The noise evaluation index is calculated based on the sound pressure level cloud map, and a three-dimensional sound field cloud map of the helicopter is generated based on the noise evaluation index.

[0033] Secondly, this application provides a helicopter three-dimensional sound field prediction device, comprising:

[0034] The acquisition module is used to acquire observation point information and extract flight parameters from the helicopter's flight path;

[0035] The selection and attitude alignment module is used to select and align the flight parameters on the helicopter flight trajectory with the radiation spheres in the helicopter acoustic radiation sphere library to obtain the radiation sphere corresponding to the flight trajectory; the helicopter acoustic radiation sphere library is constructed using the helicopter's payload information.

[0036] The radiation module is used to radiate the radiation sphere corresponding to the flight trajectory as a sound source, and calculates the sound pressure level of the observation point under different propagation paths based on the Gaussian beam theory of wave acoustics according to the observation point information.

[0037] The total sound pressure level determination module is used to determine the total sound pressure level based on atmospheric absorption, geometric attenuation, and reflection / transmission attenuation at the observation point under different propagation paths.

[0038] The cloud map generation module is used to generate a three-dimensional sound field cloud map of a helicopter using the total sound pressure level.

[0039] Thirdly, this application provides a computer device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the helicopter three-dimensional sound field prediction method.

[0040] Fourthly, this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the aforementioned helicopter three-dimensional sound field prediction method.

[0041] Fifthly, this application provides a computer program product, including a computer program that, when executed by a processor, implements the aforementioned helicopter three-dimensional sound field prediction method.

[0042] According to the specific embodiments provided in this application, the following technical effects are disclosed:

[0043] This application provides a method, apparatus, device, medium, and product for predicting three-dimensional sound fields of helicopters. The method involves selecting and aligning the flight parameters along the helicopter's flight trajectory with radiation spheres in a helicopter acoustic radiation sphere library to obtain the radiation sphere corresponding to the flight trajectory. The helicopter acoustic radiation sphere library is constructed using the helicopter's load information. The radiation sphere corresponding to the flight trajectory is used as a sound source for radiation. Based on the observation point information and Gaussian beamforming theory of wave acoustics, the sound pressure level at the observation point under different propagation paths is calculated. The total sound pressure level is determined based on atmospheric absorption, geometric attenuation, and reflection / transmission attenuation. A three-dimensional sound field cloud map of the helicopter is generated using the total sound pressure level. By using a pre-constructed helicopter acoustic radiation sphere library, the sound source is directly determined through selection in actual prediction, advancing the sound source calculation process and greatly improving computational efficiency. The Gaussian beamforming theory based on wave acoustics achieves high computational efficiency while also providing effective prediction of three-dimensional sound fields under complex terrain. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 A schematic diagram of a helicopter three-dimensional sound field prediction method;

[0046] Figure 2 This is a diagram showing the predicted noise levels in mountainous areas.

[0047] Figure 3 A schematic diagram illustrating urban grid generation, processing, and noise prediction;

[0048] Figure 4 Schematic diagram of a helicopter acoustic radiation sphere;

[0049] Figure 5 A schematic diagram showing the selection and orientation alignment of the acoustic radiation sphere;

[0050] Figure 6 A schematic diagram for interpolation calculation of acoustic radiation sphere;

[0051] Figure 7 A schematic diagram for calculating direct sound;

[0052] Figure 8 This is a schematic diagram for calculating transmitted sound.

[0053] Figure 9 This is a schematic diagram of a high-dimensional equipartition of a sphere;

[0054] Figure 10 This is a schematic diagram for calculating reflected sound.

[0055] Figure 11 This is a schematic diagram illustrating the calculation and summary of sound pressure levels.

[0056] Figure 12 This is a schematic diagram showing the sound propagation of a sound source located at the center of the map (250, 250, 150).

[0057] Figure 13 A flowchart of a method for predicting the three-dimensional sound field of a helicopter;

[0058] Figure 14 This is a schematic diagram of the functional modules of a helicopter three-dimensional sound field prediction device. Detailed Implementation

[0059] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0060] Currently, the main technologies related to helicopter 3D sound field prediction include the following:

[0061] The first method is the geometric acoustic virtual source technique. This method calculates the original helicopter sound source point (mirror radiation point) from the observation point on each possible reflecting surface. The length of the ray connecting the observation point and the virtual source point is the sound propagation distance, and the intersection of the observation point and the reflecting surface is the reflection point. The sound pressure at the observation point can be obtained by calculating the sound radiation of the corresponding virtual source ray. The virtual source method has a simple model and good computational performance. However, when using the virtual source method to extrapolate the reflection ray, only the path of a single reflection can be obtained, which cannot account for multiple reflections in complex terrain. The increase in surface elements also significantly increases the computational cost of reflection, and the virtual source method cannot consider the shading effect of complex terrain. Therefore, it cannot meet the needs of sound field prediction in complex terrain.

[0062] The second method is computational acoustic finite element method (CAM). The finite element method subdivides a large system into smaller, simpler parts, discretizing it by constructing a mesh of the object; these parts are called finite elements. By iteratively solving the Helmholtz equation or the acoustic parabolic equation at the boundaries and in each element mesh, sound pressure information at all locations can be obtained. CAM is versatile and accurate, but as the number of meshes increases, the complex iterative solutions and convergence conditions significantly increase computation time. Especially during helicopter flight, each rotor step requires an acoustic solution, and the entire flight process often involves hundreds or thousands of steps. Therefore, CAM's computational time is too long to meet the real-time requirements of flight missions.

[0063] The third type is acoustic holography. Acoustic holography can reconstruct the sound source and sound field by measuring the sound pressure at a limited number of points on a holographic surface and combining the sound pressure information from multiple measurement points with a specific acoustic holography algorithm. Acoustic holography is relatively effective in dealing with sound field prediction problems with uncertain sound sources and sound field prediction problems inside objects. However, in large and complex terrains, the use of acoustic holography not only requires a large number of sound measurement points, but also makes it difficult to eliminate external interference factors. Therefore, it is not suitable for three-dimensional sound field prediction in complex terrains for helicopters.

[0064] Therefore, the helicopter three-dimensional sound field prediction method needs to have the following characteristics: (1) The helicopter's attitude and flight parameters are constantly changing during flight, requiring multiple calculations of sound source and sound propagation. (2) When performing flight missions in complex terrains such as mountains / urban areas, sound will be affected by terrain obstacles and will be reflected and transmitted, so it is necessary to have the ability to predict multipath sound. (3) Helicopter flight missions have strong timeliness, so it is necessary to be able to quickly perform noise prediction calculations.

[0065] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0066] In one exemplary embodiment, such as Figure 1 and Figure 13 As shown, a method for predicting the three-dimensional sound field of a helicopter is provided. This method is executed by a computer device, specifically by a terminal or server alone, or by both a terminal and a server. In this embodiment, the method includes the following steps:

[0067] Step 1601: Obtain observation point information and extract flight parameters from the helicopter flight trajectory;

[0068] Step 1602: Select and align the flight parameters on the helicopter flight trajectory with the radiation spheres in the helicopter acoustic radiation sphere library to obtain the radiation sphere corresponding to the flight trajectory; the helicopter acoustic radiation sphere library is constructed using the helicopter's payload information;

[0069] Step 1603: Use the radiating sphere corresponding to the flight trajectory as a sound source to radiate, and calculate the sound pressure level of the observation point under different propagation paths based on the Gaussian beam theory of wave acoustics according to the observation point information;

[0070] Step 1604: Determine the total sound pressure level based on atmospheric absorption, geometric attenuation, and reflection / transmission attenuation at the observation points under different propagation paths;

[0071] Step 1605: Generate a three-dimensional sound field cloud map of the helicopter using the total sound pressure level.

[0072] By implementing steps 1601 to 1605 above, the sound source can be directly selected and determined in actual prediction through the pre-constructed helicopter sound radiation sphere library, which advances the sound source calculation process and greatly improves the calculation efficiency. Based on the Gaussian beam theory of wave acoustics, the prediction effect of three-dimensional sound field under complex terrain is achieved while having high calculation efficiency.

[0073] In an exemplary embodiment, the flight parameters on the helicopter's flight trajectory are selected and their attitudes aligned with radiation spheres in a helicopter acoustic radiation sphere library to obtain the radiation sphere corresponding to the flight trajectory. Specifically, this includes:

[0074] The flight noise characteristic parameters of the radiation spheres in the helicopter acoustic radiation sphere library are used as interpolation parameters. The flight parameters on the helicopter flight trajectory are used as the target points for interpolation calculation to obtain the corresponding acoustic radiation spheres.

[0075] The corresponding acoustic radiation sphere is rotated based on the flight parameters on the flight trajectory to obtain the radiation sphere corresponding to the flight trajectory.

[0076] In an exemplary embodiment, the construction process of the helicopter acoustic radiation sphere specifically includes:

[0077] The range of characteristic parameters of the helicopter's acoustic radiation sphere during flight noise is determined based on the helicopter's configuration.

[0078] Based on the range of characteristic parameters of the helicopter's acoustic radiation sphere during flight noise, unsteady aerodynamic calculation methods are used to obtain the load information of the helicopter under different flight noise characteristic parameters.

[0079] The acoustic radiation sphere of a helicopter is calculated based on the helicopter aerodynamic noise calculation method using load information of the helicopter under different flight noise characteristic parameters.

[0080] Construct a helicopter acoustic radiation sphere library based on the aforementioned helicopter acoustic radiation sphere library.

[0081] In an exemplary embodiment, the radiating sphere corresponding to the flight trajectory is used as a sound source for radiation. Based on the observation point information and the Gaussian beamforming theory of wave acoustics, the sound pressure level at the observation point under different propagation paths is calculated. Specifically, this includes:

[0082] The radiating sphere corresponding to the flight trajectory is used as a sound source for radiation.

[0083] The propagation path of the direct sound is determined based on the observation point information and the sound source, and the sound pressure level at the observation point under the direct sound path is determined by the relative direction vector based on the propagation path of the direct sound.

[0084] Determine the direction vectors of the observation point and the sound source based on the observation point information and the sound source;

[0085] The propagation path of the transmitted sound is determined based on the normal vector of the environmental grid surface and the direction vectors of the observation point and the sound source, and the sound pressure level at the observation point under the transmission path is determined based on the propagation path of the transmitted sound and the observation point information.

[0086] Divide the radiation sphere corresponding to the flight trajectory into equal areas and generate propagation rays;

[0087] The ray path is determined based on the observation point information and the forward sound propagation calculation method of the propagating ray, and the sound pressure level of the observation point under the reflection path is determined based on the Gaussian beam theory of wave acoustics according to the ray path.

[0088] In an exemplary embodiment, the total sound pressure level is determined based on atmospheric absorption, geometric attenuation, and reflection / transmission attenuation at the observation point under different propagation paths, specifically including:

[0089] The sound pressure level of the direct sound wave is determined based on the sound pressure level at the observation point under the direct path and the sound pressure level at the observation point under the transmission path, taking into account atmospheric sound absorption effect, transmission attenuation loss and geometric loss.

[0090] The sound pressure level of the reflected sound wave is determined based on the sound pressure level at the observation point under the reflection path, taking into account atmospheric sound absorption effect, reflection attenuation loss, and geometric loss.

[0091] The total sound pressure level is obtained by summing the direct sound wave sound pressure level and the reflected sound wave sound pressure level.

[0092] In one exemplary embodiment, generating a three-dimensional sound field cloud map of a helicopter using the total sound pressure level specifically includes:

[0093] The total sound pressure level is summarized according to the time information to obtain a sound pressure level cloud map;

[0094] The noise evaluation index is calculated based on the sound pressure level cloud map, and a three-dimensional sound field cloud map of the helicopter is generated based on the noise evaluation index.

[0095] In one exemplary embodiment, before extracting flight parameters from the helicopter's flight path, it is necessary to model the environment, perform a meshing operation, and then extract the flight parameters from the helicopter's flight path within the meshed environment.

[0096] In one exemplary embodiment, this application also provides the following specific solution, taking the helicopter three-dimensional sound field prediction method for helicopter three-dimensional flight in urban and mountainous areas as an example:

[0097] The first step, based on the helicopter configuration, preliminarily determines the range of flight noise characteristic parameters for the helicopter's acoustic sphere. Unsteady rotor aerodynamic calculation methods, such as predetermined or free wakes, are applied to obtain information such as the helicopter's load under different flight noise characteristic parameters. Flight noise characteristic parameters are of particular interest in calculating helicopter acoustic radiation, used for calculating the acoustic sphere and selecting the sphere for specific trajectories. Flight parameters are all parameters during flight, including flight noise characteristic parameters. The flight attitude and flight position (x, y, z) parameters within the flight parameters determine the helicopter's specific shape, equivalent to information about the sound emission location during propagation calculations. Using the obtained load information, combined with helicopter aerodynamic noise calculation methods, the helicopter's acoustic sphere is calculated, establishing a... Figure 4 The helicopter acoustic radiation sphere shown is a storage container. This storage container, used as a reserve, can meet the needs of different flight missions.

[0098] The second step involves generating a flight scene mesh based on the needs of the helicopter flight mission, used for calculating the propagation of helicopter noise in complex terrain. Specifically, terrain information for mountains and urban areas is obtained using geographic mapping software such as ArcGIS and Baidu Maps, and modeled in software such as Catia. The mesh is then read in and subdivided in Blender. Figure 3 As shown.

[0099] The third step involves generating a flight trajectory in the flight scenario and obtaining the flight noise characteristic parameters along the trajectory. Specifically, based on the helicopter configuration, the range of flight noise characteristic parameters for the helicopter's acoustic radiating sphere is initially determined. Unsteady rotor aerodynamic calculation methods, such as predetermined wakes or free wakes, are applied to obtain information such as the helicopter's loads under different flight noise characteristic parameters. Using this load information, combined with the FW-H equations for helicopter aerodynamic noise calculation, the helicopter's acoustic radiating sphere is calculated, establishing a... Figure 4 The helicopter acoustic radiation sphere shown contains, Figure 4 In this context, μ represents the forward ratio, and a TPP C is the pitch angle of the propeller disk. t This is the tensile coefficient.

[0100] The fourth step involves interpolating the acoustic radiation spheres to obtain the corresponding acoustic radiation spheres at each discrete point of the flight trajectory. Using the helicopter's acoustic radiation sphere as the sound source, sound rays are radiated outwards from the sphere's surface in uniformly discrete patterns. Reflection and transmission occur when these rays interact with surface elements (urban buildings, mountainous terrain). Vector calculations are used to continue tracking the reflected and transmitted sound rays until they attenuate to background noise levels or escape the map's range. Since the rays generated by the forward calculation method may not reach the observation point precisely, beam diffusion calculations are performed at each observation location according to Gaussian beamforming theory. This yields the sound pressure component p at the observation point. i (z,r). By calculating and summing all direct, reflected, and transmitted sound at the observation point using the same method, the final total sound pressure p can be obtained. all .

[0101] Specifically, at each discrete point on the flight trajectory, the flight noise characteristic parameters corresponding to that point are used for... Figure 5 The selection and attitude alignment of the acoustic radiation sphere shown are important. Since acoustic radiation calculations cannot cover all flight noise characteristic parameters, the selection of the radiation sphere requires careful consideration. Figure 6 The interpolation calculation is shown below. Three flight noise characteristic parameters from the established acoustic radiation sphere library are used as interpolation parameters. The flight noise characteristic parameters of discrete flight points are used as the target points for interpolation. The acoustic radiation sphere information corresponding to a discrete point is obtained by interpolation using an eight-sphere library surrounding that discrete point. After obtaining the acoustic radiation sphere, it is rotated according to the given flight attitude information.

[0102] Parameters (x,y,z) and (γ,a) TPP It is used for spatial positioning of the secondary acoustic radiation sphere.

[0103] Figure 5 A schematic diagram of the spatial positioning of the secondary acoustic radiation sphere is provided. The specific implementation process is as follows: First, based on the helicopter's spatial position parameters (z, y, z), the center of the secondary acoustic radiation sphere is positioned at the trajectory control point. Second, azimuth positioning is performed based on the helicopter's equivalent flight trajectory angle and rotor disk tilt angle—the 0° angle of attack plane of the secondary acoustic radiation sphere is rotated to coincide with the rotor disk plane during actual helicopter flight; specifically, the secondary acoustic radiation sphere is rotated γ around the y-axis. + a TPP γ is the pitch angle of the helicopter flight, a TPP It is the rotor disc tilt angle during helicopter flight.

[0104] After locating the secondary acoustic radiation sphere, the secondary sound source points corresponding to different ground observation points can be determined. Generally, rotor noise propagates in a straight line from the center of the rotor hub to the ground observation point, as shown by R in the diagram. o R represents the vector from the origin to the observation point. rR represents the vector from the origin to the center of sound radiation. or The vector from the radiation center to the observation point is represented by R in the figure. or As shown by the vector. Vector R or The intersection point with the secondary sound radiation sphere is the corresponding secondary sound radiation point. The elevation angle of the corresponding secondary sound radiation point is... The formula for calculating the azimuth (θ) is:

[0105]

[0106] In the formula, Let be a unit vector in the observation coordinate system, and let be a vector relative to the ground coordinate system. The conversion formula is as follows:

[0107]

[0108] The ball hangar established in this application uses three flight noise characteristic parameters. Therefore, in practical use, one-dimensional linear interpolation is required in all three dimensions: lift coefficient, rotor disk angle of attack, and advance ratio. The three-dimensional interpolation process for the ball hangar is described below. Figure 6 As shown. Where i is the number of a specific point, point... The corresponding parameter value is V iii Then the target point P(μ, α) TPP C t The calculation of the corresponding parameter value V is as follows:

[0109]

[0110] The fifth step is to calculate the noise (direct, reflected, and transmitted) for different paths using different tracking methods.

[0111] (1) Direct shot

[0112] like Figure 7 As shown, the propagation path of the direct sound is determined based on the relative position of the observation point and the center point of the radiation sphere, and the sound pressure level at the corresponding point on the sound radiation sphere is determined by the relative direction vector.

[0113] (2) Transmission

[0114] like Figure 8 As shown, in the calculation of sound radiation in mountainous and urban areas, due to the complex terrain and the influence of buildings, there are many observation points that cannot be directly reached from the sound source. Classification of whether an observation point is directly reachable can be achieved by judging the ray from the sound source to the observation point based on whether it is blocked. The judgment method is as follows:

[0115] 1) Calculate the normal vector of all environmental mesh surfaces and the direction vector from the mesh point to the sound source point (taking the structured mesh as an example). Calculate the normal vector of the surfaces formed by each pair of points.

[0116] 2) Calculate the direction vectors between the observation point and the sound source point. Calculations are performed by traversing all mesh surfaces. and The cross product is used to determine whether the ray from the sound source and the observation point intersects on the grid surface. and If all cross products have the same sign, then it means... If the distance from the grid surface to the trajectory point is greater than the distance from the observation point to the trajectory point when the grid surface intersects with the trajectory surface, it means that the observation point is occluded by the grid surface.

[0117] 3) The propagation path of the transmitted sound is obtained after calculation. The sound pressure level (SPL) of the transmitted sound is also calculated. t The expression is:

[0118] SPL d =SPL ori -TL-ΔL

[0119] SPL ori This is the sound pressure level at the second-order radiation point, where TL represents the transmission loss. The geometric attenuation ΔL of the sound pressure level at the observation point is:

[0120]

[0121] In the formula, r2 represents the distance from the sound wave receiving point to the center of the rotor hub; r1 represents the distance from the sound source radiation point (secondary sound source radiation point) to the center of the rotor hub.

[0122] The sound transmission loss TL is calculated using the mass law, where ρ represents the material density, s represents the material thickness, and f is the sound frequency.

[0123] TL = 20log 10 (ρsf)-47 (airborne sound) (6)

[0124] (3) Reflection

[0125] This application employs a forward-propagating sound propagation calculation method, discretizing the radiated sound into several beams whose sound pressure is normally distributed (Gaussian distribution) along the beam center. Finally, the sound pressure of the discrete beams is summed and calculated at the observation point. The specific calculation steps are as follows:

[0126] 1) such as Figure 9 As shown, the acoustic radiation sphere is divided into equal areas. Since there is no strict mathematical theory on the equal division of a sphere, this application uses an algorithm based on probability theory (generating n points in d-dimensional space from a standard normal distribution, and arbitrarily selecting two points, the distance between the two points is likely to be the same) to generate n equally divided rays.

[0127] 2) Project rays with given direction vectors forward, and provide several termination criteria: ① Set the minimum and maximum X, Y, and Z values ​​of the observation point position to map boundary values; when the ray reaches the map boundary, the ray path is no longer calculated; ② When the ray intersects the grid, reflection occurs; when the ray reflects the environment grid n times, the ray path is no longer calculated; ③ When the ray has traveled a certain distance, the ray path is no longer calculated. Record the interaction position with the surface grid each time, the distance traveled, etc., for subsequent calculations. Figure 10 As shown, where R dir Indicates the direct path, R ref Indicates the reflection path, R trans Indicates the transmission path.

[0128] 3) Sound calculations are performed at each reflected point of the ray. Since the arrival point is not exactly at the observation point, Gaussian beam theory is needed to calculate the sound pressure at adjacent observation points. Figure 11 The calculation is shown below. Here, z represents the propagation distance of the central ray, r represents the distance from a point on the beam to the center point, p(z) is the sound pressure intensity at the center point of the ray, which can be obtained using the FW-H equation or the acoustic radiation sphere method, and exp(-iω(t(z,r))) is the sound field wave term, representing the propagation function of the Gaussian beam from the center point outwards. ω is the angular velocity. T is the period, where:

[0129]

[0130] In numerical calculations, the parameters in the equations will vary depending on different initial discretization methods (different number of beams, different acoustic sphere radii, etc.). z0 represents the radius of the acoustic sphere, i.e., the propagation distance from the sound source point to the acoustic sphere. p(z0) represents the sound pressure at any point on the acoustic sphere. Both are given as initial conditions by the information from the acoustic sphere.

[0131] p i (z0,r i ) represents the sound pressure component calculated using the Gaussian beam method on the radiating sphere, and d(z0) represents the negligible distance at which the ray attenuates outwards. P(z0)=∑p i (z0,r i From this, the Gaussian function can be obtained. The constant value A and the parameter d(z0) are given. dis is the distance from the sound source to the observation point, and t(z,r) represents the propagation time from the sound source to the point of calculation component. t(z,r) can be obtained by the ratio of the propagation distance to the speed of sound c.

[0132]

[0133] like Figure 11 As shown, after calculating the discrete rays, the sound pressure at a given observation point can be obtained by superimposing the central rays near it, where P(R,ω) represents the desired observation point location and R represents the distance from the observation point to the sound source. After calculating the discrete rays, the sound pressure at a given observation point can be obtained by superimposing the central rays near it.

[0134] P(R,ω)=∑p i (z,r) (10)

[0135]

[0136] Where, p i (z,r) represents a certain acceptable sound pressure level at the observation point, where... Figure 11 For example, p(z) is the sound pressure intensity at the center of the ray, and p1(z,r) is the sound pressure at a distance r outward from the center. The subscript 1 or 2 indicates the ray number that can be received at that observation point.

[0137]

[0138] The sixth step involves summarizing and processing all calculation results throughout the flight time, calculating atmospheric attenuation and other information, as well as the sound pressure level distribution at different times and the average sound pressure level distribution over the entire period. The results are then output as a noise cloud map and data file. Finally, a three-dimensional sound field cloud map of the helicopter under complex terrain is obtained.

[0139] Specifically, information such as atmospheric sound absorption attenuation is calculated, and sound pressure level (SPL) information is summarized over time to generate a sound pressure level cloud map.

[0140] p(r) represents the noise sound pressure received at the observation point at a distance r from the sound source. s ) represents the sound pressure level at the sound source point; r s Let p be the radius of the sound source radiating sphere, and let the absorption coefficient α represent the attenuation intensity of atmospheric sound absorption on noise energy. h This represents the reference sound pressure level, which is the minimum audible threshold for the human ear. When atmospheric sound absorption is taken into account, the relationship between the noise sound pressure received at the observation point and the sound pressure from the sound source is:

[0141]

[0142] SPL (Sound Pressure Level) information is summarized over time and a SPL contour map is generated. Noise assessment indicators such as sound exposure level are also calculated and their contour maps are generated. The calculation formulas are as follows:

[0143]

[0144] SEL represents the sound exposure level at the ground observation point. SPL-A represents the A-weighted sound pressure level, which takes into account the human physiological sensitivity to mid- and high-frequency noise and insensitivity to low-frequency noise. n represents the number of discrete points, and i represents the discrete point number of the helicopter flight path. Δt represents the exposure time of the secondary acoustic sphere corresponding to each radiation point, i.e., the time difference between discrete points, with 1 sec expressed in seconds. Figure 12 As shown, the image illustrates the sound propagation of a point sound source located at the center of the map (250, 250, 150), providing total noise sound pressure level contour maps for 0 seconds, 0.5 seconds, and 1 second of propagation. Sound exposure levels were also calculated throughout the entire time history. Figure 12 (a) in the diagram is the total noise sound pressure level contour map of a point source propagating for 0 seconds. Figure 12 (b) in the diagram is a contour map of the total noise sound pressure level after 0.5 seconds of propagation from a point source. Figure 12 (c) in the diagram represents the total noise sound pressure level contour map of a point source propagating for 1 second. Figure 12 (d) in the diagram represents the calculated total noise exposure level for the entire flight process.

[0145] After summarizing the SPL information over time and generating a SPL contour map, the following is obtained: Figure 2 The predicted results are shown.

[0146] The advantages and benefits of this application are as follows: (1) By pre-establishing a sound radiation sphere library, the calculation of helicopter aerodynamic noise sources is advanced, which greatly improves the calculation efficiency of flight sound field prediction. (2) Compared with the geometric acoustic virtual source method, this application uses Gaussian beam theory based on wave acoustics, which has higher calculation efficiency and can realize the calculation of direct, reflected and transmitted noise propagation paths under complex terrain, resulting in better prediction effect. (3) Compared with the computational acoustic finite element method, rapid path tracing calculation can be performed at several discrete trajectory points during flight to obtain the noise map of the entire flight mission, which can meet the timeliness requirements of flight missions.

[0147] Based on the same inventive concept, this application also provides a helicopter three-dimensional sound field prediction device for implementing the helicopter three-dimensional sound field prediction method described above. The solution provided by this device is similar to the solution described in the above method. Therefore, the specific limitations of one or more helicopter three-dimensional sound field prediction device embodiments provided below can be found in the limitations of the helicopter three-dimensional sound field prediction method above, and will not be repeated here.

[0148] In one exemplary embodiment, such as Figure 14 As shown, a helicopter three-dimensional sound field prediction device is provided, comprising:

[0149] The acquisition module 1701 is used to acquire observation point information and extract flight parameters from the helicopter's flight trajectory.

[0150] The selection and attitude alignment module 1702 is used to select and align the flight parameters on the helicopter flight trajectory with the radiation spheres in the helicopter acoustic radiation sphere library to obtain the radiation sphere corresponding to the flight trajectory; the helicopter acoustic radiation sphere library is constructed using the helicopter's load information.

[0151] The radiation module 1703 is used to radiate the radiation sphere corresponding to the flight trajectory as a sound source, and to calculate the sound pressure level of the observation point under different propagation paths based on the Gaussian beam theory of wave acoustics according to the observation point information.

[0152] The total sound pressure level determination module 1704 is used to determine the total sound pressure level based on atmospheric absorption, geometric attenuation, and reflection / transmission attenuation at the observation point under different propagation paths.

[0153] The cloud map generation module 1705 is used to generate a three-dimensional sound field cloud map of a helicopter using the total sound pressure level.

[0154] In one exemplary embodiment, a computer device is provided, which may be a server or a terminal. The computer device includes a processor, memory, input / output interfaces (I / O), and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is connected to the system bus via the I / O interfaces. The processor of the computer device provides computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system, computer programs, and a database. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The database of the computer device stores helicopter three-dimensional sound field prediction data. The input / output interfaces of the computer device are used for exchanging information between the processor and external devices. The communication interface of the computer device is used for communicating with external terminals via a network connection. When the computer program is executed by the processor, it implements a helicopter three-dimensional sound field prediction method.

[0155] Those skilled in the art will understand that the structures shown in this application are merely block diagrams of some structures related to the solutions of this application, and do not constitute a limitation on the computer device to which the solutions of this application are applied. Specific computer devices may include more or fewer components than shown in the figures, or combine certain components, or have different component arrangements. In an exemplary embodiment, a computer device is provided, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the above-described method embodiments.

[0156] In one exemplary embodiment, a computer-readable storage medium is provided storing a computer program that, when executed by a processor, implements the above-described method embodiments.

[0157] In one exemplary embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the above-described method embodiments.

[0158] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0159] In this application, all actions to acquire signals, information, or data are carried out in compliance with the relevant data protection laws and policies of the country where the location is situated, and with the authorization granted by the owner of the relevant device.

[0160] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM).

[0161] The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0162] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0163] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for predicting the three-dimensional sound field of a helicopter, characterized in that, The helicopter three-dimensional sound field prediction method includes: Acquire observation point information and extract flight parameters from the helicopter's flight path; The flight parameters on the helicopter's flight trajectory are selected and their attitudes aligned with the radiation spheres in the helicopter acoustic radiation sphere library to obtain the radiation sphere corresponding to the flight trajectory; the helicopter acoustic radiation sphere library is constructed using the helicopter's payload information; The radiation sphere corresponding to the flight trajectory is used as a sound source for radiation. Based on the Gaussian beam theory of wave acoustics, the sound pressure level of the observation point is calculated under different propagation paths according to the observation point information. The total sound pressure level is determined based on atmospheric absorption, geometric attenuation, and reflection / transmission attenuation at the observation points under different propagation paths. A three-dimensional sound field cloud map of a helicopter is generated using the total sound pressure level.

2. The helicopter three-dimensional sound field prediction method according to claim 1, characterized in that, By selecting and aligning the flight parameters along the helicopter's flight trajectory with the radiation spheres in the helicopter acoustic radiation sphere library, and performing attitude alignment, the radiation sphere corresponding to the flight trajectory is obtained, specifically including: The flight noise characteristic parameters of the radiation spheres in the helicopter acoustic radiation sphere library are used as interpolation parameters. The flight parameters on the helicopter flight trajectory are used as the target points for interpolation calculation to obtain the corresponding acoustic radiation spheres. The corresponding acoustic radiation sphere is rotated based on the flight parameters on the flight trajectory to obtain the radiation sphere corresponding to the flight trajectory.

3. The helicopter three-dimensional sound field prediction method according to claim 1, characterized in that, The construction process of the helicopter acoustic radiation sphere specifically includes: The range of characteristic parameters of the helicopter's acoustic radiation sphere during flight noise is determined based on the helicopter's configuration. Based on the range of characteristic parameters of the helicopter's acoustic radiation sphere during flight noise, unsteady aerodynamic calculation methods are used to obtain the load information of the helicopter under different flight noise characteristic parameters. The acoustic radiation sphere of a helicopter is calculated based on the helicopter aerodynamic noise calculation method using load information of the helicopter under different flight noise characteristic parameters. Construct a helicopter acoustic radiation sphere library based on the aforementioned helicopter acoustic radiation sphere library.

4. The helicopter three-dimensional sound field prediction method according to claim 1, characterized in that, The radiating sphere corresponding to the flight trajectory is used as a sound source for radiation. Based on the Gaussian beam theory of wave acoustics, the sound pressure level at the observation point is calculated under different propagation paths according to the observation point information. Specifically, this includes: The radiating sphere corresponding to the flight trajectory is used as a sound source for radiation. The propagation path of the direct sound is determined based on the observation point information and the sound source, and the sound pressure level at the observation point under the direct sound path is determined by the relative direction vector based on the propagation path of the direct sound. Determine the direction vectors of the observation point and the sound source based on the observation point information and the sound source; The propagation path of the transmitted sound is determined based on the normal vector of the environmental grid surface and the direction vectors of the observation point and the sound source, and the sound pressure level at the observation point under the transmission path is determined based on the propagation path of the transmitted sound and the observation point information. Divide the radiation sphere corresponding to the flight trajectory into equal areas and generate propagation rays; The ray path is determined based on the observation point information and the forward sound propagation calculation method of the propagating ray, and the sound pressure level of the observation point under the reflection path is determined based on the Gaussian beam theory of wave acoustics according to the ray path.

5. The helicopter three-dimensional sound field prediction method according to claim 4, characterized in that, The total sound pressure level is determined based on atmospheric absorption, geometric attenuation, and reflection / transmission attenuation at observation points under different propagation paths. Specifically, this includes: The sound pressure level of the direct sound wave is determined based on the sound pressure level at the observation point under the direct path and the sound pressure level at the observation point under the transmission path, taking into account atmospheric sound absorption effect, transmission attenuation loss and geometric loss. The sound pressure level of the reflected sound wave is determined based on the sound pressure level at the observation point under the reflection path, taking into account atmospheric sound absorption effect, reflection attenuation loss, and geometric loss. The total sound pressure level is obtained by summing the direct sound wave sound pressure level and the reflected sound wave sound pressure level.

6. The helicopter three-dimensional sound field prediction method according to claim 1, characterized in that, Generating a 3D sound field cloud map of a helicopter using the total sound pressure level, specifically including: The total sound pressure level is summarized according to the time information to obtain a sound pressure level cloud map; The noise evaluation index is calculated based on the sound pressure level cloud map, and a three-dimensional sound field cloud map of the helicopter is generated based on the noise evaluation index.

7. A helicopter three-dimensional sound field prediction device, characterized in that, The helicopter three-dimensional sound field prediction device includes: The acquisition module is used to acquire observation point information and extract flight parameters from the helicopter's flight path; The selection and attitude alignment module is used to select and align the flight parameters on the helicopter flight trajectory with the radiation spheres in the helicopter acoustic radiation sphere library to obtain the radiation sphere corresponding to the flight trajectory; the helicopter acoustic radiation sphere library is constructed using the helicopter's payload information. The radiation module is used to radiate the radiation sphere corresponding to the flight trajectory as a sound source, and calculates the sound pressure level of the observation point under different propagation paths based on the Gaussian beam theory of wave acoustics according to the observation point information. The total sound pressure level determination module is used to determine the total sound pressure level based on atmospheric absorption, geometric attenuation, and reflection / transmission attenuation at the observation point under different propagation paths. The cloud map generation module is used to generate a three-dimensional sound field cloud map of a helicopter using the total sound pressure level.

8. A computer device, comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the computer program to implement the helicopter three-dimensional sound field prediction method according to any one of claims 1-6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the helicopter three-dimensional sound field prediction method as described in any one of claims 1-6.

10. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the helicopter three-dimensional sound field prediction method as described in any one of claims 1-6.

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