Aircraft aerodynamic noise simulation method and system

Abstract

The present application belongs to the technical field of aircraft aerodynamic noise simulation data processing, and specifically relates to an aircraft aerodynamic noise simulation method and system thereof. By solving the convection equation derived from the unitized random frozen turbulent velocity, the turbulent velocity field after convection is obtained, and then the random turbulent velocity field is synthesized with the new random frozen turbulent velocity field, and the convection effect of the mean flow is introduced, which can better reflect the influence of the mean flow on the statistical spatiotemporal correlation of turbulence, and will not have additional influence on non-convective problems. The convection equation is simple in form, and the calculation cost will not be significantly increased while ensuring the stability of the solution. The computing resources can be efficiently utilized, and the fitting accuracy of strong convection problems can be effectively improved, which promotes the accurate simulation of aircraft aerodynamic noise and provides reliable support for the advanced design of aircraft.

Description

Technical Field

[0001] The present application belongs to the technical field of aircraft aerodynamic noise simulation data processing, and in particular relates to an aircraft aerodynamic noise simulation method and system thereof. Background Art

[0002] Aerodynamic noise is widely present in aircraft equipment. For example, in the field of civil aviation, the deployment of lift-enhancing devices and wheel structures of large aircraft during takeoff and landing will cause large-scale airflow separation, forming serious aerodynamic noise, which has an adverse impact on the takeoff and landing environment and passenger health.

[0003] Simulation is an important technical means to study aerodynamic noise. However, compared with other macroscopic variables, the amplitude of acoustic pulsation is usually several orders of magnitude smaller and the spectral distribution is wide, which makes conventional computational fluid dynamics (CFD) simulation difficult in the actual aerodynamic noise prediction problem. One of the most significant problems is the difficulty in balancing simulation accuracy and efficiency. If reliable sound field simulation information is to be obtained, the spatial and temporal discrete density must be increased, which consumes a lot of computing resources.

[0004] At present, facing the characteristics of acoustic disturbance variables, many time-space discrete formats with high precision, low dissipation, low dispersion and high spectral resolution have been developed. On this basis, by separating the sound source capture and the sound propagation simulation, a variety of hybrid computational aeroacoustic CAA methods have been formed. In order to improve the efficiency of sound source capture, random turbulence reconstruction models based on turbulence statistical variable information are often used to replace the reconstructed sound source. The random turbulence velocity field generated by this type of model meets the two-point time-space correlation and energy spectrum characteristics of statistical turbulence, and only relies on the time-averaged flow information. It has high application potential and value in broadband noise problems.

[0005] At present, the most commonly used random turbulence reconstruction model is the random Fourier modal model (RFM), which uses the superposition of a finite number of random Fourier modes in the wavenumber domain to simulate the spectral-spatial characteristics of turbulence. It uses an isotropic turbulent kinetic energy spectrum, which cannot accurately describe the influence of the mean flow on the statistical spatiotemporal correlation of turbulence. When dealing with severe convection problems, the problem of reconstructed turbulent kinetic energy offset occurs. The fitting accuracy is insufficient, making it difficult to achieve accurate simulation of aerodynamic noise, which affects the advanced design of aircraft.

[0006] This application is proposed in view of the above-mentioned technical defects. Summary of the invention

[0007] The purpose of the present application is to provide an aircraft aerodynamic noise simulation method and system thereof to overcome or alleviate at least one aspect of the known technical deficiencies.

[0008] The technical solution of this application is:

[0009] On the one hand, a method for simulating aircraft aerodynamic noise is provided, comprising:

[0010] Step 1: Determine the sound source area and define the sound source solution domain;

[0011] Step 2: Determine the parameters of the random Fourier modal model RFM;

[0012] Step 3: In the sound source solution domain, a random frozen turbulent velocity field is generated using a random Fourier modal model (RFM);

[0013] Step 4: Solve the convection equation derived from the unitized random frozen turbulent velocity to obtain the turbulent velocity field after convection;

[0014] Step 5: In the sound source solution domain, a new random frozen turbulent velocity field is generated using a random Fourier modal model RFM;

[0015] Step 6: Use the turbulent velocity field after convection and the new random frozen turbulent velocity field to synthesize the random turbulent velocity field that reflects the convection effect, iterate along time, and reconstruct the sound source.

[0016] Optionally, in the above-mentioned aircraft aerodynamic noise simulation method, step 1 specifically includes:

[0017] Under the sound source reconstruction hybrid computational aeroacoustic method process, the Reynolds average equation RANS simulation on the CFD grid is used to obtain average flow information and statistical turbulence information. The average flow information includes the average density, average velocity, and average pressure of the flow field, and the statistical turbulence information includes the turbulent kinetic energy and turbulent dissipation rate of the flow field. Then, the sound source area is determined according to the flow distribution characteristics.

[0018] According to the sound source area, the sound source solution domain is delineated on the CAA grid, the average flow information and statistical turbulence information are interpolated from the CFD grid to the CAA grid, and pre-smoothing is performed;

[0019] According to the relationship between the boundary direction of the sound source area and the average flow direction, the inflow and outflow boundaries of the sound source area are determined.

[0020] Optionally, in the above-mentioned aircraft aerodynamic noise simulation method, in step 2, the parameters of the random Fourier modal model RFM are determined, specifically including the discrete range in the wavenumber domain, the number of discrete modes, the time and space scale scaling factor, the turbulence length cutoff scale, and the wavenumber discretization method.

[0021] Optionally, in the above-mentioned aircraft aerodynamic noise simulation method, step three is specifically:

[0022] On the CAA grid, within the sound source solution domain, for each discrete wave number mode, a wave number space variable with unified physical space is generated, and a random frozen turbulent velocity field is generated by a random Fourier modal model RFM, where:

[0023] ;

[0024] in;

[0025] is the random freezing turbulence velocity;

[0026] is the Fourier mode order;

[0027] For the The turbulence velocity amplitude corresponding to the first-order Fourier mode;

[0028] For the The wave number vector corresponding to the order Fourier mode;

[0029] is the position of the turbulent velocity field;

[0030] For the The phase corresponding to the order Fourier mode;

[0031] For the The velocity direction unit vector corresponding to the order Fourier mode;

[0032] ;

[0033] in,

[0034] For the The turbulent kinetic energy spectrum corresponding to the first-order Fourier mode;

[0035] is the difference in wave numbers between adjacent modes;

[0036] ;

[0037] in,

[0038] To calculate the constant, take 1.453;

[0039] is the turbulent kinetic energy;

[0040] is the maximum energetic wave number;

[0041] is the inverse of the Kolmogorov scale;

[0042] ;

[0043] in,

[0044] is the turbulence integral length scale;

[0045] ;

[0046] in,

[0047] is the turbulent dissipation rate;

[0048] is the dynamic viscosity coefficient of the fluid.

[0049] Optionally, in the above-mentioned aircraft aerodynamic noise simulation method, in step 4, the convection equation derived from the unitized random frozen turbulent velocity is specifically:

[0050] ;

[0051] in,

[0052] is the turbulent velocity after convection;

[0053] is the turbulent velocity amplitude;

[0054] is the unitized turbulent velocity;

[0055] To calculate the time step;

[0056] are the components of the mean flow velocity in three directions of space;

[0057] are the components of the turbulent velocity field position in three directions of space.

[0058] Optionally, in the above-mentioned aircraft aerodynamic noise simulation method, step six is ​​specifically:

[0059] ;

[0060] in,

[0061] is the random turbulence velocity reflecting the convection effect;

[0062] Freeze turbulent velocity for new randomness;

[0063] is the turbulence time scale Related functions;

[0064] ;

[0065] .

[0066] On the other hand, an aircraft aerodynamic noise simulation system is provided to implement the above-mentioned aircraft aerodynamic noise simulation method, comprising:

[0067] The sound source area determination and solution domain delineation module is used to determine the sound source area and delineate the sound source solution domain;

[0068] A parameter determination module of a random Fourier modal model RFM, used for determining parameters of the random Fourier modal model RFM;

[0069] Random frozen turbulent velocity field generation module, used to generate random frozen turbulent velocity field with random Fourier modal model RFM in the sound source solution domain;

[0070] The module for solving the turbulent velocity field after convection is used to solve the convection equation derived from the unitized random frozen turbulent velocity to obtain the turbulent velocity field after convection;

[0071] A new random frozen turbulence velocity field generation module is used to generate a new random frozen turbulence velocity field in the sound source solution domain using the random Fourier modal model RFM;

[0072] The random turbulence velocity field synthesis module for reaction convection effect is used to synthesize the random turbulence velocity field for reaction convection effect with the turbulence velocity field after convection and the new random frozen turbulence velocity field, iterate along time and reconstruct the sound source.

[0073] This application has at least the following beneficial technical effects:

[0074] Provided are an aircraft aerodynamic noise simulation method and system. By solving the convection equation derived from the unitized random frozen turbulent velocity, a turbulent velocity field after convection is obtained, and then the random turbulent velocity field is synthesized with the new random frozen turbulent velocity field, and the convection effect of the mean flow is introduced, which can better reflect the influence of the mean flow on the statistical spatiotemporal correlation of turbulence, and will not have additional influence on non-convective problems. The convection equation is simple in form, and the calculation cost will not be significantly increased while ensuring the solution stability. It can efficiently utilize computing resources, effectively improve the fitting accuracy of strong convection problems, promote accurate simulation of aircraft aerodynamic noise, and provide reliable support for the advanced design of aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] Figure 1 is a schematic diagram of an aircraft aerodynamic noise simulation method provided in an embodiment of the present application;

[0076] Figure 2Schematic diagram of an aircraft aerodynamic noise simulation system provided in an embodiment of the present application.

[0077] In order to better illustrate the present embodiment, some parts in the drawings may be omitted, which is only used for illustrative purposes and should not be construed as limiting the present application. DETAILED DESCRIPTION

[0078] In order to make the technical solution and advantages of the present application clearer, the technical solution of the present application will be described in further detail in detail and in detail with reference to the accompanying drawings. It can be understood that the specific embodiments described here are only partial embodiments of the present application, which are only used to explain the present application, not to limit the present application. It should be noted that, for the convenience of description, only the parts related to the present application are shown in the accompanying drawings, and other related parts can refer to the general design.

[0079] In addition, unless otherwise defined, the technical terms or scientific terms used in the description of this application should be the common meanings understood by those skilled in the art in the field to which this application belongs. The term "include" used in the description of this application means that the elements or objects appearing before the term include the elements or objects listed after the term and their equivalents, but do not exclude other elements or objects.

[0080] A method for simulating aircraft aerodynamic noise, such as Figure 1 shown.

[0081] Step 1: Determine the sound source area and define the sound source solution domain.

[0082] Under the sound source reconstruction hybrid computational aeroacoustic method process, the Reynolds average equation RANS simulation on the CFD grid is used to obtain the average flow information and statistical turbulence information. The average flow information includes the average density, average velocity, and average pressure of the flow field, and the statistical turbulence information includes the turbulent kinetic energy and turbulent dissipation rate of the flow field. Then, the sound source area is determined according to the flow distribution characteristics.

[0083] After determining the sound source area, the sound source solution domain can be delineated on the CAA grid, the mean flow information and statistical turbulence information can be interpolated from the CFD grid to the CAA grid, and pre-smoothing can be performed.

[0084] According to the relationship between the boundary direction of the sound source area and the average flow direction, the inflow and outflow boundaries of the sound source area can be determined.

[0085] Step 2: Determine the parameters of the random Fourier modal model RFM.

[0086] Determine the parameters of the random Fourier modal model RFM, including the discrete range in the wavenumber domain, the number of discrete modes, the time and space scale scaling factor, the turbulence length cutoff scale, the wavenumber discretization method, etc.

[0087] Step 3: In the sound source solution domain, a random frozen turbulent velocity field is generated using a random Fourier modal model (RFM).

[0088] On the CAA grid, within the sound source solution domain, for each discrete wavenumber mode, a unified wavenumber space variable in the physical space is generated, and a random frozen turbulent velocity field is generated using the random Fourier modal model RFM. The random frozen turbulent velocity field satisfies the two-point correlation in the statistical turbulent space.

[0089] ;

[0090] in;

[0091] is the random freezing turbulence velocity;

[0092] is the Fourier mode order;

[0093] For the The turbulence velocity amplitude corresponding to the first-order Fourier mode;

[0094] For the The wave number vector corresponding to the order Fourier mode;

[0095] is the position of the turbulent velocity field;

[0096] For the The phase corresponding to the order Fourier mode;

[0097] For the The velocity direction unit vector corresponding to the order Fourier mode.

[0098] ;

[0099] ;

[0100] in,

[0101] For the The turbulent kinetic energy spectrum corresponding to the first-order Fourier mode;

[0102] is the difference in wave numbers between adjacent modes.

[0103] ;

[0104] in,

[0105] To calculate the constant, take 1.453;

[0106] is the turbulent kinetic energy;

[0107] is the maximum energetic wave number;

[0108] is the inverse of the Kolmogorov scale.

[0109] ;

[0110] in,

[0111] is the turbulence integral length scale.

[0112] ;

[0113] in,

[0114] is the turbulent dissipation rate;

[0115] is the dynamic viscosity coefficient of the fluid.

[0116] Step 4: Solve the convection equation derived from the unitized random frozen turbulent velocity to obtain the turbulent velocity field after convection.

[0117] The convection equation derived from the unitized random frozen turbulent velocity is as follows:

[0118] ;

[0119] in,

[0120] is the turbulent velocity after convection;

[0121] is the turbulent velocity amplitude;

[0122] is the unitized turbulent velocity;

[0123] To calculate the time step;

[0124] are the components of the mean flow velocity in three directions of space;

[0125] are the components of the turbulent velocity field position in three directions of space.

[0126] Yes , and have .

[0127] When solving the convection equation derived from the unitized random frozen turbulent velocity, a 5-point 4th-order central difference format is used to solve the first-order gradient at the interior point, a 5-point format one-sided difference template is used at the outlet boundary of the convection equation, and a SNGR-Bailly model that can locally solve the uniform convection effect is introduced at the inlet boundary of the convection equation, as follows:

[0128] ;

[0129] in,

[0130] It is a uniform convection effect;

[0131] is the average value of the mean flow velocity at the inlet boundary.

[0132] The 4-level standard Runge-Kutta scheme is used for time marching when solving the convection equations derived from the unitized random frozen turbulent velocity.

[0133] Step 5: In the sound source solution domain, a new random frozen turbulent velocity field is generated using the random Fourier modal model RFM.

[0134] The new random frozen turbulent velocity field satisfies the two-point correlation in the statistical turbulent space and is unrelated to the random frozen turbulent velocity field generated in step three. The specific generation method can refer to step three. When generating a new random frozen turbulent velocity field, new random Fourier modal model RFM parameters are set, which will not be repeated here.

[0135] Step 6: Use the turbulent velocity field after convection and the new random frozen turbulent velocity field to synthesize the random turbulent velocity field that reflects the convection effect.

[0136] ;

[0137] in,

[0138] is the random turbulence velocity reflecting the convection effect;

[0139] Freeze turbulent velocity for new randomness;

[0140] is the turbulence time scale Related functions.

[0141] ;

[0142] .

[0143] Iterate along time and repeat steps 3 to 6 to obtain the time series of the random turbulence velocity field reflecting the convection effect and reconstruct the sound source.

[0144] The aircraft aerodynamic noise simulation method disclosed in the above embodiment obtains the turbulent velocity field after convection by solving the convection equation derived from the unitized random frozen turbulent velocity, and then synthesizes the random turbulent velocity field with the new random frozen turbulent velocity field, introduces the convection effect of the mean flow, and can better reflect the influence of the mean flow on the statistical spatiotemporal correlation of turbulence, and will not have additional impact on non-convective problems. The convection equation is simple in form, and will not significantly increase the calculation cost while ensuring the stability of the solution. It can efficiently utilize computing resources, effectively improve the fitting accuracy of strong convection problems, promote accurate simulation of aircraft aerodynamic noise, and provide reliable support for the advanced design of aircraft.

[0145] An aircraft aerodynamic noise simulation system, such as Figure 2 As shown, including:

[0146] The sound source area determination and solution domain delineation module is used to determine the sound source area and delineate the sound source solution domain;

[0147] A parameter determination module of a random Fourier modal model RFM, used for determining parameters of the random Fourier modal model RFM;

[0148] Random frozen turbulent velocity field generation module, used to generate random frozen turbulent velocity field with random Fourier modal model RFM in the sound source solution domain;

[0149] The module for solving the turbulent velocity field after convection is used to solve the convection equation derived from the unitized random frozen turbulent velocity to obtain the turbulent velocity field after convection;

[0150] A new random frozen turbulence velocity field generation module is used to generate a new random frozen turbulence velocity field in the sound source solution domain using the random Fourier modal model RFM;

[0151] The random turbulence velocity field synthesis module for reaction convection effect is used to synthesize the random turbulence velocity field for reaction convection effect with the turbulence velocity field after convection and the new random frozen turbulence velocity field, iterate along time and reconstruct the sound source.

[0152] The aircraft aerodynamic noise simulation system disclosed in the above embodiment corresponds to the aircraft aerodynamic noise simulation method disclosed in the above embodiment, and the description is relatively simple. For specific related matters, please refer to the relevant description of the aircraft aerodynamic noise simulation method part. Its technical effects can also refer to the technical effects of the relevant parts of the aircraft aerodynamic noise simulation method, which will not be repeated here.

[0153] In addition, technicians in the field should also be able to realize that the various modules of the aircraft aerodynamic noise simulation system disclosed in the embodiments of the present application can be implemented by electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, this application generally describes them according to their functions. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Technicians in the field can choose to adopt different methods to implement the described functions for each specific application and its actual constraints, but such implementation should not be considered to be beyond the scope of this application.

[0154] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. Those skilled in the art should understand that the scope of protection of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the scope of protection of the present application.

Claims

1. A method for simulating aircraft aerodynamic noise, characterized in that: include: Step 1: Determine the sound source area and define the sound source solution domain; Step 2: Determine the parameters of the random Fourier modal model RFM; Step 3: In the sound source solution domain, a random frozen turbulent velocity field is generated using a random Fourier modal model (RFM); Step 4: Solve the convection equation derived from the unitized random frozen turbulent velocity to obtain the turbulent velocity field after convection; Step 5: In the sound source solution domain, a new random frozen turbulent velocity field is generated using a random Fourier modal model RFM; Step 6: Using the turbulent velocity field after convection and the new random frozen turbulent velocity field, synthesize the random turbulent velocity field that reflects the convection effect, iterate along time, and reconstruct the sound source; Step three is as follows: On the CAA grid, within the sound source solution domain, for each discrete wave number mode, a wave number space variable with unified physical space is generated, and a random frozen turbulent velocity field is generated by a random Fourier modal model RFM, where: in; v T (x) is the random frozen turbulent velocity; N is the Fourier mode order; V n (x) is the turbulence velocity amplitude corresponding to the nth-order Fourier mode; k n is the wave number vector corresponding to the n-th order Fourier mode; x is the position of the turbulent velocity field; φ n is the phase corresponding to the n-th order Fourier mode; σ n is the velocity direction unit vector corresponding to the n-th order Fourier mode; in, E(x,k n ) is the turbulent kinetic energy spectrum corresponding to the n-th order Fourier mode; △k is the difference in wave numbers between adjacent modes; in, A is the calculation constant, which is 1.453; K(x) is the turbulent kinetic energy; k e (x) is the maximum energetic wave number; k η (x) is the inverse of the Kolmogorov scale; k e (x)=9πA / 55L(x); in, L(x) is the turbulence integral length scale; k η (x)=e 1 / 4 (x)u -3 / 4 (x); in, ε(x) is the turbulent dissipation rate; υ(x) is the dynamic viscosity coefficient of the fluid; In step 4, the convection equation derived from the normalized random frozen turbulent velocity is: in, is the turbulent velocity after convection; is the turbulent velocity amplitude; is the unitized turbulent velocity; △t is the calculation time step; are the components of the mean flow velocity in three directions of space; x i 、x j 、x k are the components of the turbulent velocity field position in three directions of space; When solving the convection equation derived from the unitized random frozen turbulent velocity, a 5-point 4th-order central difference format is used to solve the first-order gradient at the interior point, a 5-point format one-sided difference template is used at the outlet boundary of the convection equation, and a SNGR-Bailly model that can locally solve the uniform convection effect is introduced at the inlet boundary of the convection equation. Specifically: in, v T (x, t) is the uniform convection effect; is the average value of the mean flow velocity at the inlet boundary; Step 6 is as follows: in, v t (x,t+△t) is the random turbulence velocity of the reaction convection effect; Freeze turbulent velocity for new randomness; a, b are related to the turbulence time scale τ s (x) related functions; 2. The aircraft aerodynamic noise simulation method according to claim 1, characterized in that: Step 1 specifically includes: Under the sound source reconstruction hybrid computational aeroacoustic method process, the Reynolds average equation RANS simulation on the CFD grid is used to obtain average flow information and statistical turbulence information. The average flow information includes the average density, average velocity, and average pressure of the flow field, and the statistical turbulence information includes the turbulent kinetic energy and turbulent dissipation rate of the flow field. Then, the sound source area is determined according to the flow distribution characteristics. According to the sound source area, the sound source solution domain is delineated on the CAA grid, the average flow information and statistical turbulence information are interpolated from the CFD grid to the CAA grid, and pre-smoothing is performed; According to the relationship between the boundary direction of the sound source area and the average flow direction, the inflow and outflow boundaries of the sound source area are determined.

3. The aircraft aerodynamic noise simulation method according to claim 2, characterized in that: In step 2, the parameters of the random Fourier modal model (RFM) are determined, including the discrete range in the wavenumber domain, the number of discrete modes, the time and space scale scaling factor, the turbulence length cutoff scale, and the wavenumber discretization method.

4. An aircraft aerodynamic noise simulation system, used to implement the aircraft aerodynamic noise simulation method according to claim 1, characterized in that: include: The sound source area determination and solution domain delineation module is used to determine the sound source area and delineate the sound source solution domain; A parameter determination module of a random Fourier modal model RFM, used for determining parameters of the random Fourier modal model RFM; Random frozen turbulent velocity field generation module, used to generate random frozen turbulent velocity field with random Fourier modal model RFM in the sound source solution domain; The module for solving the turbulent velocity field after convection is used to solve the convection equation derived from the unitized random frozen turbulent velocity to obtain the turbulent velocity field after convection; A new random frozen turbulence velocity field generation module is used to generate a new random frozen turbulence velocity field in the sound source solution domain using the random Fourier modal model RFM; The random turbulence velocity field synthesis module of the reaction convection effect is used to synthesize the random turbulence velocity field of the reaction convection effect with the turbulence velocity field after convection and the new random frozen turbulence velocity field, iterate along time and reconstruct the sound source; In the random frozen turbulent velocity field generation module, on the CAA grid, within the sound source solution domain, for each discrete wave number mode, a wave number space variable with unified physical space is generated, and a random frozen turbulent velocity field is generated using the random Fourier modal model RFM, which includes: in; v T (x) is the random frozen turbulent velocity; N is the Fourier mode order; V n (x) is the turbulence velocity amplitude corresponding to the nth-order Fourier mode; k n is the wave number vector corresponding to the n-th order Fourier mode; x is the position of the turbulent velocity field; φ n is the phase corresponding to the n-th order Fourier mode; σ n is the velocity direction unit vector corresponding to the n-th order Fourier mode; in, E(x,k n ) is the turbulent kinetic energy spectrum corresponding to the n-th order Fourier mode; △k is the difference in wave numbers between adjacent modes; in, A is the calculation constant, which is 1.453; K(x) is the turbulent kinetic energy; k e (x) is the maximum energetic wave number; k η (x) is the inverse of the Kolmogorov scale; k e (x)=9πA / 55L(x); in, L(x) is the turbulence integral length scale; k η (x)=e 1 / 4 (x)u -3 / 4 (x); in, ε(x) is the turbulent dissipation rate; υ(x) is the dynamic viscosity coefficient of the fluid; In the module for solving the turbulent velocity field after convection, the convection equation derived from the unitized random frozen turbulent velocity is: in, is the turbulent velocity after convection; is the turbulent velocity amplitude; is the unitized turbulent velocity; △t is the calculation time step; are the components of the mean flow velocity in three directions of space; xi, x j 、x k are the components of the turbulent velocity field position in three directions of space; When solving the convection equation derived from the unitized random frozen turbulent velocity, a 5-point 4th-order central difference format is used to solve the first-order gradient at the interior point, a 5-point format one-sided difference template is used at the outlet boundary of the convection equation, and a SNGR-Bailly model that can locally solve the uniform convection effect is introduced at the inlet boundary of the convection equation. Specifically: in, v T (x, t) is the uniform convection effect; is the average value of the mean flow velocity at the inlet boundary; In the random turbulence velocity field synthesis module of reaction convection effect, the random turbulence velocity field of reaction convection effect is synthesized, specifically: in, v t (x,t+△t) is the random turbulence velocity of the reaction convection effect; Freeze turbulent velocity for new randomness; a, b are related to the turbulence time scale τ s (x) related functions;

Images