Turbulent boundary layer data generation method and system based on turbulent coherent structure

Abstract

The present application discloses a method and system for generating turbulent boundary layer data based on turbulent coherent structure, the method comprising: establishing an average streamwise velocity model in a turbulent boundary layer, and establishing a root mean square distribution model of streamwise pulsating velocity, normal pulsating velocity and spanwise pulsating velocity; constrained by the root mean square distribution model of streamwise pulsating velocity, using velocity strips to construct streamwise pulsating velocity; constrained by the root mean square distribution model of spanwise and normal pulsating velocity, using the induced velocity of streamwise vortex to construct normal pulsating velocity and spanwise pulsating velocity; based on the average streamwise velocity, streamwise pulsating velocity, normal pulsating velocity and spanwise pulsating velocity, and introducing random disturbance, synthesizing and obtaining velocity components in a turbulent boundary layer. The present application can realize the rapid generation of a turbulent boundary layer, and the turbulent data generated by the method can be used as the inlet boundary conditions and initial value conditions of the initial field for turbulent numerical calculation.

Description

Technical Field

[0001] The present application relates to the technical field of fluid mechanics, and in particular to a method and system for generating turbulent boundary layer data based on a turbulent coherent structure. Background Art

[0002] The boundary layer is the simplest of all flow phenomena. Even such a simple model will go through a laminar stage, then a transition stage from laminar to turbulent, and finally a fully developed turbulent stage as it develops downstream. The turbulent boundary layer involves many aspects of the industrial field, such as turbulent drag reduction, turbulent noise, turbulent vibration, etc. All of these need to start from the simplest boundary layer flow research and gradually move towards practical application, so the boundary layer has become the basis of turbulence research.

[0003] For the spatially developed turbulent boundary layer, it is very sensitive to the upstream conditions. Therefore, when using numerical simulation methods (large eddy simulation LES or direct numerical simulation DNS) to simulate the turbulent boundary layer, its inlet boundary conditions are very important and directly related to the success of the numerical calculation. For example, Figure 1 As shown in the figure. Because the flow information (especially the pulsation information) at the turbulent inlet is unknown and changes with time, it usually needs to be given manually during simulation. Whether the artificial pulsation information conforms to the statistical characteristics of turbulence and whether the downstream fully developed turbulence obtained is close to the real turbulence has become a problem of great concern to researchers.

[0004] For the study of turbulent inlet conditions, the most basic approach is to use the instantaneous flow parameters Decomposition into average parameters and pulsation parameters The average parameter is obtained by time or space integration and averaging, while the pulsation parameter is the difference between the instantaneous parameter and the average parameter, as shown in formula (1). Represents any flow parameter such as velocity or temperature.

[0005]

[0006] In recent years, many scholars at home and abroad have carried out research in this area, which can be roughly divided into the following three categories:

[0007] 1. Construct turbulent inlet data through experimental data or DNS calculation data. This type of method requires experimental data or DNS calculation data to be given in advance, which limits the use of this method;

[0008] 2. The average parameter profile and the pulsating parameter profile at the inlet are given separately, and then the turbulent inlet data are synthesized. The success of this type of method depends entirely on the method of giving the average profile and the pulsating profile. It is difficult to give a profile that accurately meets the fully developed turbulent characteristics;

[0009] 3. Through the flow quasi-periodic boundary conditions, auxiliary calculations are constructed to obtain turbulent inlet data. This type of method is based on the similarity law of the turbulent boundary layer. After data processing, the downstream flow information is introduced into the upstream as the upstream inlet condition, thus becoming an approximate periodic condition.

[0010] The three commonly used methods for generating turbulence data have their own inherent defects:

[0011] 1. The turbulent inlet data is constructed by experimental data or DNS calculation data. This type of data is only suitable for the same flow conditions as the test or calculation, and is not universal, which limits the use of this method;

[0012] 2. The average parameter profile and the pulsating parameter profile at the inlet are given respectively, and then the turbulent inlet data are synthesized. The success of the synthesis method depends entirely on the given method of the average profile and the pulsating profile. The physical mechanism of the turbulent structure is not introduced, and the profile of the fully developed turbulent characteristics cannot be accurately met;

[0013] 3. Periodic boundary conditions require the construction of auxiliary calculations to obtain turbulent inlet data. This type of algorithm requires additional computational effort and also introduces unrealistic pseudo-periodic information. Summary of the invention

[0014] In view of this, the present application provides a method and system for generating turbulent boundary layer data based on turbulent coherent structure.

[0015] The present application discloses a method for generating turbulent boundary layer data based on a turbulent coherent structure, which comprises:

[0016] Step 1: Obtain the average streamwise velocity, average normal velocity and average spanwise velocity in the turbulent boundary layer;

[0017] Step 2: Use the velocity strip to give the streamwise pulsating velocity, and use the induced velocity of the streamwise vortex to give the normal pulsating velocity and the spanwise pulsating velocity;

[0018] Step 3: Based on the streamwise average velocity, average normal velocity and average spanwise velocity, as well as the streamwise pulsating velocity, normal pulsating velocity and spanwise pulsating velocity, and introducing random disturbances, the velocity components in the turbulent boundary layer are obtained.

[0019] Furthermore, the step 1 comprises:

[0020] By giving the nominal thickness of the boundary layer and the local Reynolds number , calculate the dissipation scale , friction speed ;

[0021] According to the local dissipation scale , friction speed , the length is measured by the dissipative scale To make it dimensionless, the velocity is measured using the wall friction velocity Make it dimensionless;

[0022] According to the local Reynolds number , and the dimensionless average streamwise velocity is obtained ; The values ​​of the average normal velocity and the average spanwise velocity are both considered to be 0.

[0023] Furthermore, the dissipation scale and friction speed The expressions are:

[0024]

[0025] The flow direction coordinate x, normal coordinate y, and spanwise coordinate z in the flow field are respectively expressed by the dissipation scale Non-dimensionalization yields , , , speed quantity Use wall friction speed Non-dimensionalization yields :

[0026]

[0027] Dimensionless mean streamwise velocity The expression is:

[0028] .

[0029] Furthermore, before step 2, the method further includes:

[0030] Step 21: Change the flow to pulsating speed The root mean square distribution of Decompose into inner functions and the outer function ; Introduce weight function , the root mean square distribution The inner and outer functions are smoothly connected to obtain the flow pulsation velocity Distribution function in the normal direction Dimensionless ;

[0031] Step 22: According to step 21, the normal pulsation velocity is obtained Distribution function in the normal direction Dimensionless , and the spanwise pulsation velocity Distribution function in the normal direction Dimensionless .

[0032] Furthermore, the step 21 comprises:

[0033]

[0034] in, For inner function and the outer function The dividing point for The corresponding maximum value of the dimensionless streamwise pulsating velocity distribution;

[0035] Flow pulsation speed Distribution function in the normal direction The dimensionless , The expression is;

[0036]

[0037] Normal pulsation speed Distribution function in the normal direction The dimensionless , The expression is:

[0038]

[0039] in, and They are The corresponding inner and outer functions are: For inner function and the outer function The dividing point for The corresponding maximum value of the dimensionless normal pulsation velocity distribution;

[0040] Spanwise pulsation velocity Distribution function in the normal direction The dimensionless , The expression is:

[0041]

[0042] in, and They are The corresponding inner and outer functions are: For inner function and The dividing point for The corresponding maximum value of the dimensionless spanwise pulsating velocity distribution.

[0043] Furthermore, the flow pulsation velocity The root mean square distribution of The constraints that are satisfied are:

[0044]

[0045]

[0046] Normal pulsation speed RMS distribution in the normal direction The constraints that are satisfied are:

[0047]

[0048] Spanwise pulsation velocity RMS distribution in the normal direction The constraints that are satisfied are:

[0049]

[0050] .

[0051] Furthermore, in step 2, the velocity strip is used to give the flow pulsation velocity , The dimensionless expression of is:

[0052]

[0053] in, is the dimensionless flow pulsation velocity, is the flow pulsation velocity, z + is the dimensionless spanwise coordinate, is the bending change of the strip along the flow direction and over time, t is the time, is the bending variation;

[0054] In step 2, the induced velocity of the streamwise vortex is used to give the normal pulsating velocity and spanwise pulsation velocity ,include:

[0055] The streamwise vortex adopts the Rankine vortex model , which is the calculation point r The induction speed is:

[0056]

[0057] in, are the coordinates of the vortex core, is the circumferential induced velocity of the vortex, is the radius of the vortex core, is the maximum speed of the vortex;

[0058] Normal pulsation speed and spanwise pulsation velocity The dimensionless expressions are:

[0059]

[0060] In the formula, is the dimensionless normal pulsation velocity, is the dimensionless spanwise pulsation velocity, and represents the circumferential induced velocity of each streamwise vortex The y and z components of , m is a positive integer, and M is the total number of all streamwise vortices on the velocity strip.

[0061] Furthermore, the introduced streamwise vortex adopts a spindle model in the streamwise direction, and the expression of the parameters in the induced velocity is:

[0062] .

[0063] Furthermore, the step 3 comprises:

[0064] The velocity components in the turbulent boundary layer are obtained by superposition of the following formulas:

[0065]

[0066] in, , and They are the streamwise velocity component, normal velocity component and spanwise velocity component in the turbulent boundary layer respectively; , and are the random terms introduced in the stream direction, normal direction and span direction respectively.

[0067] The present application also discloses a turbulent boundary layer data generation system based on a turbulent coherent structure, which implements the above-mentioned method, and comprises:

[0068] A first acquisition module is used to acquire the average streamwise velocity, the average normal velocity and the average spanwise velocity in the turbulent boundary layer;

[0069] The second calculation module is used to use the velocity strip to give the streamwise pulsating velocity, and use the induced velocity of the streamwise vortex to give the normal pulsating velocity and the spanwise pulsating velocity;

[0070] The third calculation module is used to obtain the velocity components in the turbulent boundary layer according to the average streamwise velocity, the average normal velocity and the average spanwise velocity, as well as the streamwise pulsating velocity, the normal pulsating velocity and the spanwise pulsating velocity, and introduce random disturbances.

[0071] Due to the adoption of the above technical solution, the present application has the following advantages: the basic logic of the data generated by this method lies in the physically existing coherent structures (velocity strips, streamwise vortices) in the turbulent boundary. This structural form objectively exists, so the generated data will be closer to the real turbulent data. By using this as the input condition as the entry condition for DNS or LES calculation, a fully developed turbulent boundary layer can be quickly obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0073] Figure 1 A schematic diagram of turbulent boundary layer simulation in the prior art;

[0074] Figure 2 A schematic diagram of a strip structure and a streamwise vortex structure in a turbulent boundary layer according to an embodiment of the present application;

[0075] Figure 3 A schematic diagram of an example of the distribution of pulsating velocity magnitudes in a turbulent boundary layer (DNS example) in an embodiment of the present application;

[0076] Figure 4 Schematic diagram of strips and flow vortices in the longitudinal cross section of the flow field of an embodiment of the present application. DETAILED DESCRIPTION

[0077] The present application is further described in conjunction with the accompanying drawings and embodiments, and the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field should fall within the scope of protection of the embodiments of the present application.

[0078] Figure 1It is a typical schematic diagram of turbulence numerical simulation, and its boundary conditions include upstream inlet, wall, downstream outlet and far-field conditions. The most critical one is the upstream inlet condition, because the closer it is to the real turbulence data, the more realistic the flow field obtained in the simulation area is. How to give this inlet data is the core content of this application, namely the data generation technology of turbulent boundary layer. This technology is an important technology for conducting research on turbulence numerical simulation. It provides inlet boundary conditions for numerical simulation methods, such as DNS, LES, and RANS-LES methods, and is closely related to the reliability and computational efficiency of numerical methods.

[0079] The flow characteristics of the turbulent boundary layer have two characteristics: randomness and order. Randomness means that the flow parameters are always changing in time and space, while order means that there are obvious flow structures in the boundary layer, that is, coherent structures, such as the strip structure and streamwise vortex structure in the near-wall region. The so-called strip structure refers to the structure in which the streamwise velocity in the near-wall region of the boundary layer is staggered along the spanwise direction with high and low velocities, while the streamwise vortex refers to the vortex structure in the near-wall region of the boundary layer. There is a streamwise vortex-stripe theory of turbulence generation, which believes that the streamwise vortex is generated by the lateral rolling up of the strip instability, that is, the streamwise vortex is close to the strip structure, such as Figure 2 shown.

[0080] Existing studies on turbulent boundary layers have confirmed that the streamwise vortex structure mainly exists in the near-wall region of the boundary layer, that is, y < 60 (in, is the dissipation scale of the boundary layer), the average distance between the vortex core and the wall is 20 , the average flow length is about 200 , with an average radius of about 15 , propagating downstream at a speed of (0.6-0.8)U (U is the outflow velocity of the boundary layer). For the strip structure, it is mainly located at y<30 The low-speed fluid presents a strip shape that is elongated along the flow direction and changes quasi-periodically in the span direction. These velocity strips can be as long as 1000 km in the flow direction. , the average span spacing is about 100 There is a close correspondence between the spatial positions of the streamwise vortices and the strips. The streamwise vortices are always located near the strips. There are several streamwise vortices on each strip, and the average spacing between them is about 300. .

[0081] The present application provides an embodiment of a method for generating turbulent boundary layer data based on a turbulent coherent structure. In view of the randomness and orderliness of the turbulent boundary layer flow, the strip structure and streamwise vortex structure of the near-wall region of the boundary layer are constructed, and some random parameters are appropriately introduced to construct turbulent inlet data. The characteristics of turbulent flow are fully considered, and the generated data is more efficient in evolving into real turbulence. The embodiments of the present application include:

[0082] Since the turbulent field is the average flow field in the normal direction and space-time pulsating flow field The distribution of each space-time pulsation component in the normal y direction is It satisfies certain physical laws. Here, the normal distribution of the pulsating component is defined as:

[0083]

[0084] It characterizes the root mean square value of the pulsation parameters in three dimensions: flow direction x, span direction y and time t.

[0085] For each average velocity vector in a turbulent boundary layer, it is usually considered that the average streamwise velocity is is not zero, and its average normal velocity and spanwise velocity are all zero, so we only need to construct See step 4B for details.

[0086] For the spatiotemporal pulsating velocity components, firstly, the root mean square distribution of each velocity component is uniform in time t, flow direction x, and span direction z, and there is only a distribution function in the normal direction. Therefore, it is necessary to determine the distribution function of each pulsating velocity component in the normal direction , , . See step 4C for details.

[0087] The distribution function of the pulsation parameters is obtained but the specific value of the pulsation velocity is not directly given. In step 4D, the velocity strip is used to give the flow pulsation velocity. , and its RMS distribution meets the requirements in step 4C. Similarly, in step 4E, the induced velocity of the streamwise vortex is used to give the normal pulsating velocity and spanwise pulsation velocity , and its RMS distribution also meets the requirements in step 4C.

[0088] Finally, the average velocity and the pulsating velocity components are superimposed, and random disturbances are introduced to finally synthesize the velocity components in the turbulent boundary layer. See step 4F for details.

[0089] This embodiment specifically includes the following steps:

[0090] Step 4A: Determine basic parameters.

[0091] By giving the nominal thickness of the boundary layer and the local Reynolds number Calculate the local dissipation scale , friction speed ;

[0092] (2)

[0093] In the formula, is the kinematic viscosity coefficient of the fluid.

[0094] Step 4B: Calculate the mean streamwise velocity.

[0095] The average streamwise velocity profile is given by the wall law as follows: , and consider the average normal velocity and spanwise velocity All variables with a “+” superscript represent dimensionless parameters, and the length quantities are measured using the dissipation scale To make it dimensionless, such as x + ,y + ; The velocity is measured by wall friction velocity To make it dimensionless, The dimensionless mean streamwise velocity is The expression is:

[0096] (3)

[0097] In the formula, x, y, and z represent the flow direction, normal direction, and span direction coordinates in the flow field, respectively. Figure 1 as shown in .

[0098] Step 4C: RMS distribution model of the pulsating velocity magnitude along the normal direction.

[0099] Based on a large number of numerical results and experiments, the following distribution of the pulsating velocity along the normal direction is given: Figure 3 , we can see that the root mean square distribution of the three dimensionless pulsating velocities is = , = The size is an increasing function in the inner layer of the boundary layer, and a decreasing function approaching zero in the outer layer. Figure 3 The coordinates given in , Corresponding to the maximum value of the pulsation speed in each direction. Among them, For inner function and the outer function The dividing point for The corresponding maximum value of the root mean square distribution of the dimensionless streamwise pulsating velocity;

[0100] The dimensionless RMS distribution of the pulsating velocity in the stream direction Take the example of building a model and decompose it into inner functions and the outer function :

[0101] (4)

[0102] In order to make the above piecewise function at its maximum point The point is smooth and extreme, and the weight function is introduced , smoothly connect the piecewise functions as follows:

[0103] (5)

[0104] in, is the flow pulsation velocity Distribution function in the normal direction, streamwise pulsation velocity Distribution function in the normal direction The dimensionless .

[0105] It is not difficult to prove that the above function satisfy:

[0106] (6)

[0107] Normal pulsation speed and spanwise pulsation velocity The distribution functions in the normal direction are and . The dimensionless , The dimensionless , and The expressions are:

[0108] (7)

[0109] (8)

[0110] in, and They are The corresponding inner and outer functions are: For inner function and the outer function The dividing point for The corresponding maximum value of the dimensionless normal pulsation velocity distribution; and They are The corresponding inner and outer functions are: For inner function and The dividing point for The corresponding maximum value of the dimensionless spanwise pulsating velocity distribution.

[0111] The root mean square distribution of the dimensionless normal pulsating velocity is , and the dimensionless spanwise RMS distribution of the fluctuating velocity The mathematical model also satisfies the constraints similar to those in (6). The constraints that are satisfied are:

[0112]

[0113] The constraints that are satisfied are:

[0114]

[0115] .

[0116] Step 4D: Calculate the flow pulsation velocity.

[0117] Introducing velocity strips in the near-wall region of the boundary layer, the flow direction fluctuates ( ) in dimensionless form ( ) is given by:

[0118] (9)

[0119] in, is the dimensionless flow pulsation velocity, is the flow pulsation velocity, z + is the dimensionless spanwise coordinate, is the bending change of the strip along the flow direction and over time, t is the time, is the bending variation.

[0120] It can be seen that the flow-direction pulsation velocity appears in the form of a sinusoidal disturbance, where the surface disturbance amplitude of the first term of the right equation is given by the flow-direction disturbance model (4) and (5) given above. The dimensionless period width of the pulsation along the span z is the width of the velocity stripe. , usually taken as , which is the first term in the sine function; its second term is the phase change, which represents the bending change of the strip along the flow direction and over time, where represents the amplitude of the bending change, while the cosine function represents the temporal and spatial changes of the velocity strip. is the streamwise vortex length, because each bend of the strip parasitizes a streamwise vortex structure, usually .

[0121] Step 4E: Calculate the spanwise pulsating velocity and the normal pulsating velocity.

[0122] A series of streamwise vortex structures are introduced into the boundary layer inlet section. The local induced velocity of these streamwise vortices is equal to the lateral pulsating velocity. and spanwise pulsation velocity .

[0123] The streamwise vortex here adopts the Rankine vortex model , which is the calculation point r The induction speed is:

[0124] (10)

[0125] in, are the coordinates of the vortex core, is the circumferential induced velocity of the vortex (the normal induced velocity is zero), is the radius of the vortex core, is the maximum velocity of the vortex. At the same time, it is assumed that the vortex center of the flow vortex is at the shoulder of the velocity strip, such as Figure 4 shown.

[0126] Considering the previous pulsating velocity distribution model , and Only the distribution of y in the normal direction is considered, and the change in the flow direction is not considered. Therefore, the spindle model is used in the flow direction, assuming that the position of the vortex core is 1 / 2 of the distance from the wall. , and the length of the streamwise vortex is considered to be , its intensity (corresponding to the maximum speed ) is small at both ends and large in the middle, and the radius of the vortex core is 15 Therefore, the parameters in the streamwise vortex model (10) can be written as:

[0127] (11)

[0128] A streamwise vortex is generated at the shoulder of each velocity strip, totaling M. Then, the induced velocity of each streamwise vortex at the calculation point is calculated according to formula (10), and the local dimensionless normal pulsating velocity is calculated by superposition: and the dimensionless spanwise pulsating velocity .

[0129] (12)

[0130] In the formula, is the dimensionless normal pulsation velocity, is the dimensionless spanwise pulsation velocity, and represents the circumferential induced velocity of each streamwise vortex The y and z components of , m is a positive integer, and M is the total number of all streamwise vortices on the velocity strip.

[0131] Step 4F: Synthesis of turbulent boundary layer velocity.

[0132] The previous step 4B gives the average velocity in the stream direction, step 4D gives the fluctuating velocity in the stream direction, and step 4E gives the fluctuating velocity in the span direction and normal direction, where the root mean square distribution of the pulsating parameters in steps 4D and E meets the requirements in step 4C. On this basis, random pulsating terms are introduced in time and space, and the synthetic velocity of the turbulent boundary layer can be obtained by superimposing each term.

[0133] (13)

[0134] in: is the friction velocity given in (2), is the distribution of the mean velocity along the normal direction given by equation (3), is the streamwise velocity fluctuation characterized by the velocity strip introduced in equation (5), and are the spanwise and normal velocity fluctuations of the streamwise vortex signature introduced in equation (12), and , and are the random terms introduced in the stream direction, normal direction and span direction respectively.

[0135] The basic logic of the data generated by the method of this application is the coherent structure (velocity strips, streamwise vortices) that physically exists in the turbulent boundary. This structural form exists objectively, so the generated data will be closer to the real turbulent data. By using this as the input condition as the entry condition for DNS or LES calculation, a fully developed turbulent boundary layer can be quickly obtained. This application has been verified by numerical simulation, the scheme is feasible, and the results have achieved the expected goals.

[0136] The present application also provides an embodiment of a turbulent boundary layer data generation system based on a turbulent coherent structure, which implements the method described in the above embodiment, and includes:

[0137] A first acquisition module is used to acquire the average streamwise velocity, the average normal velocity and the average spanwise velocity in the turbulent boundary layer;

[0138] The second calculation module is used to use the velocity strip to give the streamwise pulsating velocity, and use the induced velocity of the streamwise vortex to give the normal pulsating velocity and the spanwise pulsating velocity;

[0139] The third calculation module is used to obtain the velocity components in the turbulent boundary layer according to the average streamwise velocity, the average normal velocity and the average spanwise velocity, as well as the streamwise pulsating velocity, the normal pulsating velocity and the spanwise pulsating velocity, and introduce random disturbances.

[0140] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application rather than to limit it. Although the present application has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present application can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present application should be included in the scope of protection of the claims of the present application.

Claims

1. A method for generating turbulent boundary layer data based on turbulent coherent structure, characterized in that: include: Step 1: Obtain the average streamwise velocity in the turbulent boundary layer, and consider the average normal velocity and the average spanwise velocity to be zero; Step 2: Use the velocity strip to give the streamwise pulsating velocity, and use the induced velocity of the streamwise vortex to give the normal pulsating velocity and the spanwise pulsating velocity; Step 3: According to the average streamwise velocity, average normal velocity and average spanwise velocity, as well as the streamwise pulsating velocity, normal pulsating velocity and spanwise pulsating velocity, random disturbances are introduced to obtain the velocity components in the turbulent boundary layer; Before step 2, the method further includes: Step 21: Change the flow to pulsating speed The root mean square distribution of Decompose into inner functions and the outer function ; Introduce weight function , the root mean square distribution The inner and outer functions are smoothly connected to obtain the flow pulsation velocity Distribution function in the normal direction Dimensionless ; Step 22: According to step 21, the normal pulsation velocity is obtained Distribution function in the normal direction Dimensionless , and the spanwise pulsation velocity Distribution function in the normal direction Dimensionless .

2. The method according to claim 1, characterized in that The step 1 comprises: By giving the nominal thickness of the boundary layer and the local Reynolds number , calculate the dissipation scale , friction speed ; According to the local dissipation scale , friction speed , the length is measured by the dissipative scale To make it dimensionless, the velocity is measured using the wall friction velocity Make it dimensionless; According to the local Reynolds number , and the dimensionless average streamwise velocity is obtained ; The values ​​of the average normal velocity and the average spanwise velocity are both considered to be 0.

3. The method according to claim 2, characterized in that Dissipation scale and friction speed The expressions are: In the formula, is the kinematic viscosity coefficient of the fluid; The flow direction coordinate x, normal coordinate y, and spanwise coordinate z in the flow field are respectively expressed by the dissipation scale Non-dimensionalization yields , , , speed quantity Use wall friction speed Non-dimensionalization yields : Dimensionless mean streamwise velocity The expression is: 。 4. The method according to claim 1, characterized in that: The step 21 comprises: in, For inner function and the outer function The dividing point of for The corresponding maximum value of the dimensionless streamwise pulsating velocity distribution; Flow pulsation speed Distribution function in the normal direction The dimensionless , The expression is; The step 22 comprises: Normal pulsation speed Distribution function in the normal direction The dimensionless , The expression is: in, and They are The corresponding inner and outer functions, For inner function and the outer function The dividing point of for The corresponding maximum value of the dimensionless normal pulsation velocity distribution; Spanwise pulsation velocity Distribution function in the normal direction The dimensionless , The expression is: in, and They are The corresponding inner and outer functions, For inner function and The dividing point of for The corresponding maximum value of the dimensionless spanwise pulsating velocity distribution.

5. The method according to claim 4, characterized in that Flow pulsation speed The root mean square distribution of The constraints that are satisfied are: Normal pulsation speed RMS distribution in the normal direction The constraints that are satisfied are: Spanwise pulsation velocity RMS distribution in the normal direction The constraints that are satisfied are: 。 6. The method according to claim 4, characterized in that In step 2, the velocity strip is used to give the flow pulsation velocity , The dimensionless expression of is: in, is the dimensionless flow pulsation velocity, is the flow pulsation velocity, z + is the dimensionless spanwise coordinate, is the bending change of the strip along the flow direction and over time, t is the time, is the bending variation; In step 2, the induced velocity of the streamwise vortex is used to give the normal pulsating velocity and spanwise pulsation velocity ,include: The streamwise vortex adopts the Rankine vortex model , which is the calculation point r The induction speed is: in, are the coordinates of the vortex core, is the circumferential induced velocity of the vortex, is the radius of the vortex core, is the maximum speed of the vortex; Normal pulsation speed and spanwise pulsation velocity The dimensionless expressions are: In the formula, is the dimensionless normal pulsation velocity, is the dimensionless spanwise pulsation velocity, and represents the circumferential induced velocity of each streamwise vortex y and z components of , m is a positive integer, and M is the total number of all streamwise vortices on the velocity strip.

7. The method according to claim 6, characterized in that The introduced streamwise vortex adopts a spindle model in the streamwise direction, and the expression of the parameters in the induced velocity is: 。 8. The method according to claim 7, characterized in that The step 3 comprises: The velocity components in the turbulent boundary layer are obtained by superposition of the following formulas: in, , and They are the streamwise velocity component, normal velocity component and spanwise velocity component in the turbulent boundary layer respectively; , and are the random terms introduced in the stream direction, normal direction and span direction respectively.

9. A turbulent boundary layer data generation system based on turbulent coherent structure, implementing the method described in any one of claims 1 to 8, characterized in that: include: A first acquisition module is used to acquire the average streamwise velocity, the average normal velocity and the average spanwise velocity in the turbulent boundary layer; The second calculation module is used to use the velocity strip to give the streamwise pulsating velocity, and use the induced velocity of the streamwise vortex to give the normal pulsating velocity and the spanwise pulsating velocity; The third calculation module is used to obtain the velocity components in the turbulent boundary layer according to the average streamwise velocity, the average normal velocity and the average spanwise velocity, as well as the streamwise pulsating velocity, the normal pulsating velocity and the spanwise pulsating velocity, and introduce random disturbances.

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