Frequency domain gust aeroacoustic response prediction method

Abstract

The invention belongs to the field of aero-acoustic numerical simulation, particularly discloses a frequency domain gust aero-acoustic response prediction method, and aims to solve the problems that an existing time domain method is low in calculation efficiency and a linear / nonlinear frequency domain method is insufficient in adaptability. The method comprises the following steps of: determining a control equation set comprising a continuity equation, a momentum equation and an energy equation, introducing a gust source item and a spongy layer source item, adding the source items into the control equation set, and solving by adopting a harmonic balance method; and converting to a frequency domain by combining sub-time-level sampling and discrete Fourier transform, adding a pseudo-time derivative item and carrying out implicit solution, and finally reconstructing to obtain an aerodynamic acoustic response. According to the method, time domain transition stage calculation is avoided, the low-frequency / long-period problem efficiency is improved, bounded gust is accurately simulated, and high-order harmonic solving resource consumption is reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of numerical simulation of aeroacoustics, and particularly relates to a frequency-domain gust aeroacoustic response prediction method. BACKGROUND

[0002] In the engineering fields of aerospace, wind energy and turbomachinery, gust is a common disturbance phenomenon, which is a velocity disturbance with specific frequency and spatial structure. Gust is usually caused by atmospheric turbulence encountered by the leading edge of an aircraft, vortex shedding, propeller wake, etc. When gust interacts with structures such as wings, cascades, wind turbine blades, it can easily induce strong aeroacoustic fluctuations and unsteady noise radiation. This kind of noise is called "leading edge noise" or "gust-induced noise", which is an important source of noise for modern aircraft, wind turbines and compressors. Traditionally, numerical simulation of this kind of problem mainly relies on time-domain calculation method. The calculation idea is to start from the initial condition and proceed in time until the final periodic steady response is obtained. This process is computationally expensive and time-consuming, especially in problems with low frequency and long period. In view of the above problems, in recent years, researchers have proposed various frequency-domain methods to improve the calculation efficiency. Harmonic balance method is one of the most representative methods. This method expands the periodic unsteady problem in time domain by Fourier transform, replaces the time derivative with a frequency-domain coupling term, and converts the original unsteady problem into a set of steady-state equations to solve. In this way, the transition stage can be skipped and the final periodic solution can be obtained directly, thus greatly improving the calculation efficiency. Although the harmonic balance method has achieved remarkable results in periodic aerodynamic problems such as turbomachinery and rotorcraft, its application in aeroacoustics is still limited, especially in the field of gust-induced aeroacoustic response. Therefore, there is an urgent need for a frequency-domain simulation method for gust-induced aeroacoustic response prediction with high efficiency and high accuracy to meet the urgent need of engineering application for fast prediction of aerodynamic noise. At present, the numerical simulation methods for gust aeroacoustic response prediction mainly include the following: 1. Time-domain method (TDM) The typical representative is a time-domain solver based on Navier-Stokes or Euler equations, supplemented by non-reflecting boundary conditions and acoustic post-processing modules. This method can directly simulate the interaction between unsteady gust and structure and its noise radiation process, but has the following obvious shortcomings: it needs to calculate a long initial transition stage, which is extremely inefficient, especially for low-frequency or long-period disturbances, whose calculation time is much longer than the real physical period; limited by time step (CFL condition), a large amount of computational resources is consumed for each iteration.

[0003] 2. Linear frequency-domain method It is suitable for small perturbation linear supersonic conditions and can quickly predict the leading edge noise in simplified scenarios. However, this method also has the following problems: only suitable for two-dimensional infinite airfoils, linear perturbations and other ideal conditions; unable to handle nonlinear effects, turbulent flow development and high-order harmonic responses in actual complex flow fields; difficult to extend to three-dimensional or turbine stage geometries and other engineering problems.

[0004] 3. Nonlinear frequency domain method Although it can handle some nonlinear effects, it faces problems such as matrix dimension explosion and solution efficiency decline when dealing with high-order harmonics or three-dimensional complex structures, and has limited coupling modeling capability in the field of aeroacoustics. In addition, most frequency domain methods do not consider how to introduce a spatially limited, frequency controllable gust source into the control equation, making it difficult to realistically simulate bounded disturbances in engineering scenarios.

[0005] In summary, the existing technology cannot balance accuracy, efficiency and wide adaptability, especially in the prediction of gust-induced aeroacoustic response, and a new, efficient and engineering-oriented frequency domain modeling and solving method is urgently needed. SUMMARY

[0006] The purpose of the present application is to provide a frequency domain gust aeroacoustic response prediction method to at least improve or solve one of the problems in the prior art.

[0007] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: A frequency domain gust aeroacoustic response prediction method, comprising: determining a control equation group to be solved; wherein the control equation group comprises a continuity equation, a momentum equation and an energy equation; determining a source term to be added; wherein the source term comprises a gust source term and a sponge layer source term; adding the source term to be added to the right end of the control equation group, solving the control equation group by using the harmonic balance method to obtain a final solution; and reconstructing the final solution to obtain an aeroacoustic response prediction result.

[0008] Preferably, in the step of adding the source term to be added to the right end of the control equation group, the control equation group obtained comprises: determining the conservation form of the control equation group as:

[0009] wherein, is a conservative variable, is a convection flux vector, is a viscous flux vector, is a source term; V denotes the volume of a control unit, Arepresents the area of a certain face of the control unit.

[0010] Preferably, the step of adding the source terms to be added to the right-hand side of the control equations includes adding the gust source term to the right-hand side of the momentum equation and adding the sponge layer source terms to the right-hand side of the continuity equation, the momentum equation and the energy equation, respectively.

[0011] Preferably, the step of determining the control equations to be solved includes closing the control equations by adding the ideal gas state equation.

[0012] Preferably, the step of adding the source terms includes adding the gust source term and the sponge layer source term, wherein the gust source term includes: ; wherein, , are the components of the gust source term to be introduced in the and directions, respectively, , are the incoming flow density and velocity, , is the velocity disturbance to be generated, is the physical time, is an intermediate variable introduced; is a monotonically increasing function, and represent the first and second derivatives of , respectively;

[0013]

[0014] wherein, is the gust amplitude, , are the gust wave numbers in the and directions, respectively, is the gust angular frequency; furthermore, is a window function used to limit the gust to a strip of height ;

[0015] wherein, is a constant used to control the spatial distribution of the gust in the direction.

[0016] Preferably, the step of adding the source terms includes adding the gust source term and the sponge layer source term, wherein the sponge layer source term includes:

[0017]

[0018] wherein, is a source term of the sponge layer, is the maximum strength of the sponge layer, represents the width of the sponge layer, denotes the depth of the sponge layer, ; , is an integer; ζ is a damping coefficient, is a reference value of the conservative variable.

[0019] Preferably, the source term to be added is added to the right end of the control equation system, the control equation system is solved by using the harmonic balance method, and a final solution is obtained, including: moving the convection flux vector and the viscous flux vector to the right end of the control equation system, and using the finite volume method for spatial discretization to obtain a discrete equation; wherein the discrete equation includes a residual term; the conservative variable and the residual term are both approximately expanded into a truncated Fourier series form; the truncated Fourier series form of the conservative variable and the residual term is brought into the discrete equation to obtain a first intermediate equation; the conservative variable and the residual term are both uniformly sampled at sub-time levels to obtain corresponding sampling results, respectively; wherein each of the sub-time levels is obtained based on a flow period determined by the gust frequency; the discrete Fourier transform is applied to each of the sampling results to obtain a transformed term; the transformed term is brought into the first intermediate equation to obtain a steady-state equation; a pseudo-time derivative term is added to the steady-state equation to obtain a second intermediate equation; the second intermediate equation is implicitly processed to obtain a final equation; the final equation is iteratively solved, and the converged result is taken as a solution of the steady-state equation , the discrete Fourier transform is applied to the solution of the steady-state equation to obtain a solution of the first intermediate equation, and the corresponding Fourier coefficients of the solution are reconstructed to obtain the conservative variable at each time as a transient flow field at each time.

[0020] Compared with the prior art, the application has the following beneficial effects: The scheme converts the periodic unsteady problem into a frequency domain steady equation for solving by the harmonic balance method, avoids the time-consuming transition stage calculation in the traditional time domain method, and is especially suitable for low-frequency or long-period gust problems. The gust source term is directly used to generate non-divergent velocity disturbance in the momentum equation, avoiding pseudo-noise; the sponge layer source term is used to suppress sound reflection at the boundary, ensuring the authenticity of sound wave propagation.

[0021] The scheme strictly limits the gust in a strip region by using a window function and a spatial distribution parameter, avoids full-basin pollution, and is more accurate in simulating the bounded gust.

[0022] In the sponge layer source term of the scheme, the damping coefficient gradually changes along the depth of the sponge layer, realizing smooth attenuation of sound waves, and the compatibility with the unsteady solving algorithm is better than that of the traditional characteristic boundary condition, realizing efficient elimination of boundary reflection.

[0023] The scheme converts the nonlinear term to the time domain calculation by sub-time level sampling and discrete Fourier transform, significantly reduces the resource consumption of high-order harmonic solving, and solves the rigidity problem of the frequency domain coupled equation set by combining pseudo-time step promotion and implicit processing, thereby improving the iteration efficiency compared with direct matrix solving. BRIEF DESCRIPTION OF DRAWINGS

[0024] The drawings accompanying the specification of this application serve to provide a further understanding of the application, the illustrative embodiments of the application and their descriptions serve to explain the application, and do not constitute an improper limitation on the application. In the drawings: Figure 1 A flowchart of a frequency domain gust aerodynamic acoustic response prediction method according to an embodiment of the application is shown in the figure; Figure 2 A schematic diagram of a wing leading edge noise problem in an embodiment of the application is shown in the figure, (a) is a pressure disturbance field; and (b) is a transverse velocity distribution; Figure 3 A comparison example graph of numerical solutions and Amiet analytical solutions of wing surface pressure distributions under different gust amplitudes and wave numbers in an embodiment of the application is shown in the figure, the red hollow circles are numerical solutions, and the blue solid lines are analytical solutions; Figure 4 A comparison of numerical solutions and Amiet analytical solutions of far-field acoustic directivity distributions under different wave numbers in an embodiment of the application is shown in the figure, (a) ; (b) ; (c) ; (d) ; the red solid line is a numerical solution, and the black hollow circle is an analytical solution; Figure 5 A gust and blade cascade interaction example graph in an embodiment of the application is shown in the figure, (a) is a pressure disturbance field; and (b) directional velocity disturbance field; Figure 6 The left side of the figure is the real part of the pressure disturbance, and the right side of the figure is the aerodynamic acoustic response caused by the interaction of the gust and the blade cascade in the embodiment of the present application. The left side of the figure is the real part of the pressure disturbance, and the right side of the figure is the aerodynamic acoustic response caused by the interaction of the gust and the blade cascade in the embodiment of the present application. DETAILED DESCRIPTION The embodiments in the present application and the features in the embodiments can be combined with each other without conflict, which will be described in detail below with reference to the drawings and in combination with the embodiments. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0025] The following detailed description is exemplary description, which is intended to provide further detailed description of the present application. Unless otherwise specified, all technical terms used in the present application have the same meaning as that generally understood by the general technical personnel in the field to which the present application belongs. The terms used in the present application are only for describing the specific embodiments, and are not intended to limit the exemplary embodiments according to the present application.

[0026] Embodiment 1 The present application is a method for efficiently predicting aerodynamic noise response under the action of gust in the frequency domain by using the harmonic balance method (HBM), which aims to solve the problem of low calculation efficiency and long time consumption of the aerodynamic acoustic response induced by gust in periodic unsteady flow, especially in the case where the traditional time domain method needs to go through a long transition process to obtain a stable periodic solution.

[0027] The key technical points of the present application mainly lie in the synergistic processing of three aspects of gust excitation, aerodynamic acoustic response and efficient solution in the frequency domain. First, by introducing a gust modeling method based on momentum source form, a spatially local, frequency controllable and non-rotational disturbance field can be constructed in the numerical calculation domain, thereby avoiding the pseudo-noise problem caused by the traditional boundary injection method. Second, in terms of solution strategy, the harmonic balance method is used to transform the original unsteady control equation into a frequency domain coupled steady system, and the time derivative is replaced by discrete Fourier transform, which effectively compresses the calculation time. Finally, by introducing a sponge layer sound absorbing boundary, a non-reflective boundary processing compatible with the harmonic balance method is realized, thereby ensuring the physical accuracy of sound wave propagation. The comprehensive application of these technical points makes the method achieve a good balance between precision and efficiency, and has the ability to handle nonlinear high-order harmonics.

[0028] As shown in FIG. 1, a frequency domain gust aerodynamic acoustic response prediction method comprises: Figure 1 S1, determining a control equation group to be solved; wherein the control equation group comprises a continuity equation, a momentum equation and an energy equation; S1, determining a control equation group to be solved; wherein the control equation group comprises a continuity equation, a momentum equation and an energy equation; It should be noted that before solving the control equations, the computational domain and grid need to be constructed, and the background flow field needs to be generated through steady-state calculations.

[0029] In a preferred embodiment, the control equations are closed by adding the ideal gas state equation.

[0030]

[0031] in, is the gas constant; is the density, For static temperature.

[0032] S2. Determine source items to be added; wherein the source items include gust source items and sponge layer source items; In one embodiment, the source term The composition is as follows:

[0033] in, The gust source item needed to generate gusts is added. The sponge layer source item is added to generate the sponge layer.

[0034] By adding the gust source term on the right side of the momentum equation , the required velocity perturbation can be generated downstream of the source region. This method ensures that both the momentum source and the velocity field are divergent, thus preventing the generation of spurious noise.

[0035] In one embodiment, the relevant parameters of the required gusts include the height and width of the gust source area, the gust amplitude (relative to the incoming flow velocity), the gust wave number, etc. Based on this, the momentum source method is used to set the source area at a specific location within the computational domain and generate gusts.

[0036] Specifically, based on the above-mentioned related parameters, the gust source item determined includes: ; (4) in, , are the gust source terms that need to be introduced in Direction and The direction of the component, , are the incoming flow density and velocity respectively (without loss of generality, we can assume that the incoming flow is uniform and has only horizontal velocity components), , are the required generation velocity disturbances, For physical moments, is the introduced intermediate variable; is a monotonically increasing function, and and In the present application, is set to the form of Gaussian distribution as follows, and can be calculated accordingly and :

[0037] where, is the variance of Gaussian distribution, is the coordinate of the center of the source region; The velocity disturbance corresponding to the single-frequency gust can be expressed as follows:

[0038] where, and the disturbance amplitude in the , can be expressed as:

[0039] where, is the gust amplitude, , are the wave numbers in the and directions, respectively, is the gust angular frequency; in addition, is a window function used to limit the gust within a strip region with height , and its specific form is as follows:

[0040] where, is a constant used to control the spatial distribution of the gust in the direction.

[0041] It should be noted that in the problems related to aeroacoustics, the aerodynamic noise will be reflected from the boundaries of the computational domain. These reflected waves can have a negative impact on the flow field in the computational domain, leading to the key physical information being overwhelmed, and in some cases, even causing instability or divergence in numerical calculations. Therefore, non-reflecting boundary conditions must be used in numerical calculations to minimize or even eliminate the potential impact of reflected waves.

[0042] The present application achieves the above-mentioned goal by setting a sponge layer (also known as a buffer zone) at the outermost periphery of the computational domain. The sponge layer is achieved by adding an additional source term to the right side of the control equation system, and its specific form is as follows:

[0043]

[0044] where, is the sponge layer source term, is the maximum strength of the sponge layer, represents the width of the sponge layer, denotes the depth of the sponge layer, ; , are taken as needed, usually integers; ζ is the damping coefficient, which is the same for all conservative variables for the purpose of meeting the stability condition, the damping coefficient ζ can be represented by a spatial function in one-dimensional form; is the reference value of the conservative variable, usually the time average, that is, the solution corresponding to the steady background flow field.

[0045] S3, add the source term to be added to the right end of the control equation group, solve the control equation group by using the harmonic balance method to obtain the final solution; reconstruct the final solution to obtain the aerodynamic acoustic response prediction result.

[0046] In one embodiment, the control equation group obtained by adding the source term to be added to the right end of the control equation group in step S3 includes: determining that the control equation group to be solved is a three-dimensional compressible Navier-Stokes equation, which is composed of continuity equation, momentum equation, and energy equation, and is expressed as:

[0047] where, is the conservative variable, is the convection flux vector, is the viscous flux vector, is the source term; V denotes the volume of the control unit, A denotes the area of a certain face of the control unit.

[0048]

[0049] where, , , , , , respectively represent density, velocity vector, total internal energy, static pressure, viscous stress tensor, and heat flux vector, is the normal vector on the face of the control unit; for Newtonian fluid, the viscous stress tensor and the heat flux vector can be represented as:

[0050]

[0051] where, and represent laminar and turbulent viscosity respectively, is the specific heat at constant pressure, and represent laminar and turbulent Prandtl number respectively, is the static temperature, and I represents the identity matrix.

[0052] In one embodiment, a source term to be added is added to the right end of the control equation set, the control equation set is solved by using a harmonic balance method to obtain a final solution, including: moving the convection flux vector and the viscous flux vector to the right end of the equal sign of the control equation set, and using a finite volume method to perform spatial discretization to obtain a discrete equation; wherein the discrete equation includes a residual term; both the conservation variable and the residual term are approximately expanded into a form of a truncated Fourier series; the truncated Fourier series form of the conservation variable and the residual term is brought into the discrete equation to obtain a first intermediate equation; the conservation variable and the residual term are uniformly sampled at sub-time levels to obtain corresponding sampling results respectively; wherein each of the sub-time levels is obtained based on a flow period determined by a gust frequency; a discrete Fourier transform is applied to each of the sampling results to obtain a transformed term; the transformed term is brought into the first intermediate equation to obtain a steady-state equation; a pseudo-time derivative term is added to the steady-state equation to obtain a second intermediate equation; the second intermediate equation is implicitly processed to obtain a final equation; the final equation is iteratively solved, and a result obtained after convergence is taken as a solution of the steady-state equation; a discrete Fourier transform is applied to the solution of the steady-state equation to obtain a solution of the first intermediate equation; the conservation variable at each time is reconstructed according to the corresponding Fourier coefficient of the solution

[0053] More specifically, in one embodiment, solving the above control equation set comprises: moving the convection flux vector and the viscous flux vector to the right-hand side of the control equation set and spatially discretizing using the finite volume method to obtain the following discrete equation:

[0054] wherein, is called the time differentiation operator, is called the residual term, which can include source terms on the right-hand side of the control equation set; Based on the periodic characteristics of the gust and considering the case of a single fundamental frequency , the conservation variable and the residual term are both approximated and expanded into the form of a truncated Fourier series defined by a finite number of harmonics, denoted as :

[0055]

[0056] wherein, represents the time-averaged term, , represent the Fourier coefficients of the positive and negative frequency terms, respectively, , , and so on. is the series.

[0057] Bringing the truncated Fourier series form of the conservation variable and the residual term into the discrete equation, the first intermediate equation is obtained:

[0058] wherein, i denotes the imaginary unit; , denote the following, respectively: (20) ; (21) It can be understood that the above matrix-form equation can be directly solved by using a suitable numerical method, but the residual term often contains many nonlinear terms, which need a high number of harmonics to be analyzed. When the number of harmonics increases, the computational resources consumed increase exponentially, greatly reducing the calculation efficiency. Therefore, the above equation is converted back to the time domain for calculation by discrete Fourier transform.

[0059] Conserved variables and the residual The sub-time levels are uniformly sampled to obtain the corresponding sampling results; wherein each sub-time level is obtained by dividing the flow period determined by the gust frequency, and the sub-time levels have a total of share, ; Apply discrete Fourier transform to each sampling result to obtain each transform term:

[0060] Among them, the transformation Included in the basic cycle Stored in Conservative variables 𝑸 at the sub-time level, transformation terms Similarly, is the discrete Fourier transform matrix.

[0061] Substituting each transformation term into the first intermediate equation, we obtain the steady-state equation:

[0062] Among them, the time spectrum operator It can be seen that the form of the steady-state equation is very close to the first intermediate equation, that is, after a series of operations such as truncated Fourier series expansion and discrete Fourier transform, the time spectrum operator is used to calculate the steady-state equation. Approximately replaces the time differential operator , thus converting the original transient equations into a coupled steady-state equations.

[0063] On this basis, the dual time step method is used to accelerate the convergence of the steady-state equation, that is, adding a pseudo time derivative term to the steady-state equation to obtain the second intermediate equation:

[0064] Performing implicit processing on the second intermediate equation gives the final equation:

[0065] in, ; (25) Iteratively solve the final equation and the converged result is used as the solution of the steady-state equation , the solution to the steady-state equation Perform discrete Fourier transform to obtain the solution of the first intermediate equation , according to the solution The corresponding Fourier coefficients are reconstructed to obtain the conserved variables at each moment , as the transient flow field at each moment. The transient flow field at each moment is processed by acoustic post-processing to obtain information such as sound pressure.

[0066] In order to prove the effectiveness of the method provided by the present invention, the following is further explained with reference to specific verification examples: like Figure 2 As shown, the method described in this invention is used to study the leading edge noise caused by the interaction between gusts and the airfoil. By adding a momentum source region a certain distance upstream of the airfoil, a uniform strip of gusts can be generated downstream. The pressure disturbances generated by the interaction between the gusts and the airfoil, which propagate far into the airfoil, can also be captured and used for acoustic post-processing.

[0067] like Figure 3 As shown, Figure 3 A comparison of the numerical solution for the pressure distribution on the airfoil surface with the Amiet analytical solution is presented. The numerical results obtained using this method are in good agreement with the analytical solution for various combinations of gust amplitude and wave number, confirming the effectiveness of this method.

[0068] like Figure 4 As shown, Figure 4 The far-field directional distribution of aerodynamic noise generated by the interaction between gusts and the airfoil is demonstrated. The numerical results obtained by this method agree well with the analytical solution at different gust wave numbers, confirming its reliability in predicting aerodynamic noise.

[0069] like Figure 5 As shown, Figure 5 The pressure and velocity disturbances generated by the interaction between the gusts and the blade cascade are shown in Figure 2. For such complex structures, this method can use a higher harmonic number (generally at least three harmonics) in the calculation to capture the high-frequency nonlinear components in the flow field.

[0070] like Figure 6 As shown, Figure 6 The authors demonstrate the amplitudes of the pressure and velocity perturbations of each individual harmonic, corresponding to the fundamental, second, and third harmonics, when calculating the aeroacoustic response caused by the cascaded effects of gusts and blades using three harmonic numbers. The results reveal the formation mechanisms of the fundamental and high-frequency perturbations and analyze their respective contributions to the far-field acoustics. The results demonstrate the applicability of this method to complex, engineering-related examples, enabling rapid prediction of aerodynamic noise.

[0071] It should be noted that the method provided by the present invention is not limited to the description in the specification and implementation. Therefore, any equivalent changes or modifications made based on the structure, features and principles described in the scope of the patent application of the present invention should be included in the scope of the patent application of the present invention.

[0072] In the description of the present specification, the description of the terms "one embodiment", "an example", "a specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0073] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application rather than limit them, although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that: the specific embodiments of the present application can be modified or replaced by the same, without departing from the spirit and scope of the present application, any modification or equivalent replacement, which should be covered within the protection scope of the claims of the present application.

Claims

1. A frequency domain gust aeroacoustic response prediction method, characterized in that: include: Determining a set of control equations to be solved; wherein the set of control equations includes a continuity equation, a momentum equation, and an energy equation; Determining source items to be added; wherein the source items include gust source items and sponge layer source items; The source term to be added is added to the right side of the control equation group, and the control equation group is solved by using the harmonic balance method to obtain a final solution; the final solution is reconstructed to obtain an aeroacoustic response prediction result.

2. The frequency domain gust aeroacoustic response prediction method according to claim 1, characterized in that: In the step of adding the source term to be added to the right end of the control equation group, the control equation group obtained includes: The conservative form of the control equations is determined as: in, is a conserved variable, is the convective flux vector, is the viscous flux vector, is the source term; V represents the volume of the control unit, A Indicates the area of ​​a certain face of the control unit.

3. The frequency domain gust aeroacoustic response prediction method according to claim 1, characterized in that: In the step of adding the source term to be added to the right side of the control equation group, the gust source term is added to the right side of the momentum equation, and the sponge layer source term is added to the right sides of the continuity equation, momentum equation and energy equation respectively.

4. The frequency domain gust aeroacoustic response prediction method according to claim 1, characterized in that: In the step of determining a control equation group to be solved, the control equation group is closed by adding an ideal gas state equation.

5. The frequency domain gust aeroacoustic response prediction method according to claim 1, characterized in that: In the step where the source term includes a gust source term and a sponge layer source term, the gust source term includes: ； in, , are the gust source terms that need to be introduced in and The direction of the component, , are the incoming flow density and velocity, , is the velocity disturbance to be generated, For physical moments, is the introduced intermediate variable; and Respectively represent The first and second derivatives of is a monotonically increasing function.

6. The frequency domain gust aeroacoustic response prediction method according to claim 5, characterized in that: The velocity disturbance to be generated is expressed as follows: in, is the gust amplitude, , They are and Gust wave number in the direction, is the gust angular frequency; is a window function that limits gusts to heights of within the strip area.

7. The frequency domain gust aeroacoustic response prediction method according to claim 6, characterized in that: Window function It is expressed as follows: in, is a constant that controls the wind gusts Spatial distribution in direction.

8. The frequency domain gust aeroacoustic response prediction method according to claim 1, characterized in that: In the step where the source term includes a gust source term and a sponge layer source term, the sponge layer source term includes: in, is the sponge layer source term, ζ is the damping coefficient, is the reference value of the conserved variable, is a conserved variable.

9. The frequency domain gust aeroacoustic response prediction method according to claim 8, characterized in that: The damping coefficient ζ is expressed as follows: in, is the maximum strength of the sponge layer, Represents the width of the sponge layer, It indicates the depth into the sponge layer. ; , is an integer.

10. The frequency domain gust aeroacoustic response prediction method according to claim 2, characterized in that: The source term to be added is added to the right side of the control equations, and the control equations are solved using the harmonic balance method to obtain the final solution, including: The convective flux vector and the viscous flux vector Move to the right side of the equal sign of the governing equations and use the finite volume method to perform spatial discretization to obtain the discrete equations; wherein the discrete equations include the residual term; For conserved variables and the residual They are approximately expanded into the form of truncated Fourier series; Conserved variables and the residual Substitute the truncated Fourier series form of into the discrete equation to obtain the first intermediate equation; Conserved variables and the residual Uniformly sampling at the sub-time level to obtain corresponding sampling results; wherein each sub-time level is obtained by averaging a flow period determined by a gust frequency; Apply discrete Fourier transform to each sampling result to obtain each transform term; Substitute each transformed term into the first intermediate equation to obtain the steady-state equation; Adding pseudo-time derivative terms to the steady-state equations yields the second intermediate equation; Perform implicit processing on the second intermediate equation to obtain the final equation; Iteratively solve the final equation and the converged result is used as the solution of the steady-state equation , the solution to the steady-state equation Perform discrete Fourier transform to obtain the solution of the first intermediate equation , according to the solution The corresponding Fourier coefficients are reconstructed to obtain the conserved variables at each moment , as the transient flow field at each moment.

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