Method, device, equipment and medium for analyzing flow field propagation characteristics based on numerical methods

Abstract

The present invention discloses a method, device, equipment, and medium for analyzing flow field propagation characteristics based on numerical methods, belonging to the field of hydraulic turbine technology. The method comprises: constructing a computational physics model of the target flow field, dividing the computational physics model into a fluid domain grid and setting flow field boundary conditions, the flow state of the flow field at the initial moment, and the numerical method; extracting data from a specific area of ​​the grid to carry out unsteady calculations according to research needs, and obtaining a calculation result file; converting the time domain information in the extracted data into frequency domain information through Fourier transform, and then obtaining the frequency, amplitude, and phase characteristic distribution of the flow field based on the frequency domain information; calculating the frequency, amplitude, and phase characteristics of any position in the flow field as needed, obtaining the flow field structure at different frequencies, and completing the flow field decomposition. The method of the present invention can be used to study the flow field propagation characteristics of a specific area of ​​a fluid machinery according to needs.

Description

Technical Field

[0001] The present invention relates to the field of flow field propagation characteristics research, and in particular to a flow field propagation characteristics analysis method, device, equipment and medium based on a numerical method. Background Art

[0002] In engineering, it is sometimes necessary to understand the propagation characteristics of certain important characteristic frequencies in the flow field (such as blade and guide vane passage frequencies caused by dynamic and static interference) to assess their impact on structural vibration. The flow field structure, such as the pressure field, obtained through numerical calculations or experimental measurements is a reflection of the superposition of pressure pulsations at various frequencies and the average pressure. In other words, the flow field structure is the result of the interaction of various components. Without the use of relevant modal decomposition methods, the contribution, propagation, and other characteristics of a single frequency component cannot be determined.

[0003] To study the propagation characteristics of flow field, flow field decomposition is required. Currently, the flow field decomposition methods for turbines or other fields mainly include proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) and their variations. For example,

[0004] Paper 1: Kou Jiaqing, Zhang Weiwei, Gao Chuanqiang. Transonic buffeting modal analysis based on POD and DMD methods[J]. Acta Aeronautica Sinica, 2016, 37(9):2679-2689.

[0005] Paper 2: Kou Jiaqing, Zhang Weiwei. Dynamic modal decomposition and its application in fluid mechanics[J]. Acta Aerodynamica Sinica, 2018, 36(2): 163-179.

[0006] In the two aforementioned papers by Kou Jiaqing et al., a relatively comprehensive analysis of the POD and DMD methods was conducted. These two modal methods require matrix operations on the flow field information (vectors) to obtain the matrix's eigenvalues ​​and eigenvectors. Because the POD method has no time series requirements, its main disadvantage is that the extracted modes lack frequency domain characteristics and can only extract the main characteristics of the internal flow field from an energy perspective, making it difficult to predict the wave propagation characteristics within the turbine. As for the DMD method, due to its calculation method, the extracted modes are not orthogonal and there is mutual influence. At the same time, the eigenvalues ​​and eigenvectors have no specific physical meaning, making it difficult to reasonably predict the wave propagation characteristics of the flow field.

[0007] Therefore, current flow field decomposition methods have two drawbacks: first, they require extensive matrix computation, resulting in large errors in the calculated eigenvalues ​​(eigenvectors); second, eigenvalues ​​and eigenvectors lack specific physical meaning. Furthermore, no studies have yet been conducted using these two methods to study the propagation characteristics of flow field waves.

[0008] In the prior art, Chinese invention patent publication number CN108801588A discloses a method for visualizing frequency-domain analysis of flow field characteristics within hydraulic machinery. This patent first performs a Fourier transform on the one-dimensional flow field characteristic signal to obtain frequency and amplitude characteristics. It then uses cross-spectral analysis of multi-point monitoring values ​​to obtain axial or circumferential phase differences, and thus, the flow propagation characteristics in the axial or circumferential directions. However, this method still has the following drawbacks: first, it can only obtain two-dimensional information, and cannot obtain the propagation characteristics of the flow field in any direction; second, the number of monitoring points in this scheme is limited, which may lead to distortion. Summary of the Invention

[0009] The present invention aims to address the shortcomings of current flow field decomposition methods in the study of flow field propagation characteristics, and proposes a flow field propagation characteristics analysis method, device, equipment and medium based on numerical methods. Through the present invention, the flow field propagation characteristics of specific areas of fluid machinery can be studied according to needs.

[0010] In order to achieve the above-mentioned object of the invention, the technical solution of the present invention is as follows:

[0011] The flow field propagation characteristics analysis method based on numerical methods includes the following steps:

[0012] Construct a computational physics model of the target flow field, mesh the fluid domain of the computational physics model, and set the flow field boundary conditions, initial flow state, and numerical method;

[0013] Carry out unsteady calculations and obtain calculation result files;

[0014] Extract data from specific areas of the calculation result file grid according to research needs, convert the time domain information in the extracted data into frequency domain information through Fourier transform, and then obtain the frequency, amplitude and phase characteristic distribution of the flow field based on the frequency domain information;

[0015] The frequency, amplitude and phase characteristics of any position in the flow field are calculated as needed to obtain the flow field structure at different frequencies, thus completing the flow field decomposition.

[0016] The decomposed flow field is expressed as follows:

[0017] ;

[0018] Where, is the decomposed flow field, tIndicates time, is the three-dimensional space coordinate, Frequency The amplitude of Frequency Phase; i is an integer, i =0, 1, 2, 3,….

[0019] Preferably, the target flow field includes the internal flow field of the fluid machinery, and the fluid machinery includes a turbine and a water pump; its corresponding computational physical model is the flow-through components of the fluid machinery from the inlet to the outlet, including the volute, fixed guide vanes, movable guide vanes, impeller and tailwater pipe.

[0020] Preferably, the internal flow field of the fluid machinery includes an inlet, an outlet, a solid surface, a rotating and a stationary interface; the set flow field boundary conditions include velocity, pressure, and turbulence; the set flow field flow state at the initial moment is the initial condition; the set numerical method includes a discrete format, convergence conditions, and a calculation time step.

[0021] Furthermore, the internal flow field of the fluid machinery obtained based on the unsteady calculation results is expressed as ; Contains all frequency components and is the sum of the flow fields caused by all frequencies, expressed in series as:

[0022] ;

[0023] Where, is the flow field, is the mean flow field, Indicated by frequency The induced time-dependent flow field; t Indicates time, is the three-dimensional space coordinate, i is an integer.

[0024] The present invention also proposes a flow field propagation characteristics analysis device based on a numerical method, comprising:

[0025] a pre-processing module configured to construct a computational physics model of a target flow field, including an internal flow field of a fluid machinery, perform fluid domain meshing on the computational physics model, and set flow field boundary conditions, an initial flow state, and a numerical method;

[0026] an unsteady calculation module, wherein the unsteady calculation module is configured to perform unsteady calculations and obtain calculation result files;

[0027] A data processing module is configured to extract data from a specific area in the calculation result file grid according to research needs, convert the time domain information in the extracted data into frequency domain information through Fourier transform, and then obtain the frequency, amplitude and phase characteristic distribution of the flow field based on the frequency domain information;

[0028] The flow field decomposition module is configured to calculate the frequency, amplitude and phase characteristics of any position in the flow field as needed, obtain the flow field structure at different frequencies, and complete the flow field decomposition.

[0029] Preferably, the flow field decomposition module calculates the frequency, amplitude and phase characteristics of any position in the flow field as needed to obtain the flow field structure at different frequencies, which can be expressed as follows:

[0030] ;

[0031] Where, is the decomposed flow field, t Indicates time, is the three-dimensional space coordinate, Frequency The amplitude of Frequency The phase, i is an integer, i =0, 1, 2, 3,….

[0032] Preferably, the pre-processing module includes:

[0033] A model building unit, the model building unit being configured to build a computational physical model of a flow-through component from an inlet to an outlet of a fluid machinery where a target flow field is located;

[0034] a grid division unit configured to perform grid division on a fluid domain of a computational physics model;

[0035] A parameter setting unit, wherein the parameter setting unit is configured to set the flow field boundary conditions, the flow field flow state at the initial moment and the numerical method of the fluid machinery inlet, outlet, solid surface, rotating and stationary interface. The set flow field boundary conditions include velocity, pressure, and turbulence. The set flow field flow state at the initial moment is the initial condition; the set numerical method includes the discrete format, convergence condition, and calculation time step.

[0036] Furthermore, the present invention also proposes a flow field propagation characteristics analysis device based on a numerical method, comprising:

[0037] memory for storing computer programs;

[0038] The processor is configured to implement the steps of the above-mentioned method for analyzing flow field propagation characteristics based on a numerical method when executing the computer program.

[0039] The present invention also proposes a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps in the flow field propagation characteristics analysis method based on the numerical method are implemented.

[0040] In summary, the present invention has the following advantages:

[0041] 1. The present invention uses unsteady numerical calculations, performs data processing on the calculation results, and adopts Fourier transform to obtain the spectral characteristics of the flow field. The flow field decomposition process based on Fourier transform is mathematically rigorous, and the obtained modes are strictly orthogonal. It can obtain the propagation characteristics of flow field fluctuations at specific frequencies and realize the study of flow field propagation characteristics in specific areas.

[0042] 2. When performing flow field decomposition, the present invention can extract massive grid data from the calculation result file as needed. Based on the spatial distribution of data points, the spatial distribution of specific frequency phase and amplitude can be obtained, which is very helpful for studying the propagation characteristics of flow field fluctuations.

[0043] 3. In addition to being applied to the field of hydraulic turbines, the present invention can also be extended to other fields such as fluid machinery and fluid mechanics. The flow field propagation characteristics of specific areas of fluid machinery can be studied according to needs, such as the propagation of pressure fluctuations caused by dynamic and static interference of hydraulic turbines, and the application prospects are broad. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 Flow chart for the implementation of the present invention;

[0045] Figure 2 The pressure field propagation characteristics in the rotating domain in Example 1 of the present invention are shown in FIG. (a) 22 f n Frequency amplitude distribution, (b) represents 22 f n Phase distribution of frequency, (c) represents 22 f n Frequency-induced propagation characteristics of the pressure field;

[0046] Figure 3 The pressure field propagation characteristics in the static domain in Example 1 of the present invention are shown in FIG. (a) 18 f n Frequency amplitude distribution, (b) represents 18 f n Frequency phase distribution, (c) represents 18 f n Frequency-induced propagation characteristics of the pressure field;

[0047] Figure 4 Figure 2 shows the propagation of pressure at a frequency of 40 Hz in the volute of Example 2 of the present invention. (a) shows the amplitude distribution of the 40 Hz frequency, (b) shows the phase distribution of the 40 Hz frequency, and (c) shows the pressure field propagation caused by the 40 Hz frequency.

[0048] Figure 5 This is the computational physical model of the main flow-through components of the turbine, with distances between the five flow-through components.

[0049] Figure 6 for Figure 5 Cross-sectional view along plane AA, viewed along the Z direction.

[0050] In the picture:

[0051] 1. Runner, 2. Movable guide vanes, 3. Fixed guide vanes, 4. Volute, 5. Draft tube.

[0052] Description of the colors in the attached figure: red represents a large value, the redder the color, the larger the value; blue represents a small value, the bluer the color, the smaller the value; other colors represent values ​​between the maximum and minimum values, which is the same as the color distribution pattern of the rainbow: red → orange → yellow → green → blue → indigo → violet. DETAILED DESCRIPTION

[0053] In order to more clearly illustrate the present invention, the present invention is further described below in conjunction with preferred embodiments and drawings. Those skilled in the art should understand that the following specific description is illustrative rather than restrictive and should not be used to limit the scope of protection of the present invention.

[0054] The present invention provides a flow field propagation characteristics analysis method based on numerical methods, such as Figure 1 As shown, the following steps are included:

[0055] Step 1: Construct a computational physics model of the target flow field, divide the fluid domain grid of the computational physics model, and set the flow field boundary conditions, initial flow state and numerical method.

[0056] In this step, the target flow field can be the internal flow field of a fluid machinery. This solution is applicable to fluid machinery including, but not limited to, turbines and pumps. The corresponding computational physics model is the flow-through components from inlet to outlet, including the volute, fixed guide vanes, movable guide vanes, runner, and draft tube.

[0057] In this step, the fluid domain meshing of the computational physics model can be implemented using existing meshing software.

[0058] In this step, the internal flow field of the fluid machinery includes the pressure field and velocity field of the fluid domain inside the flow-through component from the inlet to the outlet. The set flow field boundary conditions include velocity, pressure, turbulence, etc.; the set initial flow state of the flow field is the initial condition; the set numerical method includes the discrete format, convergence condition, calculation time step, etc.

[0059] Step 2: Carry out unsteady calculations and obtain the calculation result file.

[0060] In this step, the result files during the calculation process and the final result files are retained.

[0061] According to the unsteady calculation results, the internal flow field of the fluid machinery can be obtained . Contains all frequency components and is the sum of the flow fields caused by all frequencies, expressed in series as:

[0062] ;

[0063] Where, is the flow field, such as pressure field, velocity field, etc. is the average flow field (independent of time), Indicated by frequency The time-dependent flow field caused by t Indicates time, is the three-dimensional space coordinate, i is an integer.

[0064] Step 3: Extract data from specific areas of the result file grid according to research needs, convert the time domain information in the extracted data into frequency domain information through Fourier transform, and then obtain the frequency, amplitude and phase characteristic distribution of the flow field based on the frequency domain information.

[0065] In this step, data from specific regions within the calculation result file is extracted based on research needs. Specific regions, such as the runner and guide vane regions, include spatial coordinates and flow field physical quantities. For example, if researchers need to study the dynamic-static interference effect in the guide vane region, data from the guide vane region should be extracted. Data from the fixed guide vanes and volute can also be considered.

[0066] In this step, by directly extracting the data from the grid of the calculation result file, we can ensure a large number of data points (for unsteady calculations, the number of grid nodes is on the order of hundreds of thousands or even millions). In addition, based on the spatial distribution of the data points, we can obtain the spatial distribution of specific frequencies, phases, and amplitudes, which is very beneficial for studying the propagation characteristics of flow field fluctuations.

[0067] In this step, the time domain information is information related to time and is extracted from the result file retained during the calculation process.

[0068] The Fourier transform formula is as follows:

[0069] ;

[0070] Where, represents the signal in the time domain, represents the frequency domain signal after Fourier transform; Indicates time, represents a natural constant, Indicates frequency, represents the imaginary unit, Represents three-dimensional space coordinates.

[0071] After Fourier transform, we get a series of frequencies , amplitude and phase , where i is an integer, .

[0072] In this step, the frequency Amplitude and phase Frequency domain information contains spatial coordinates , that is, after Fourier transform, the frequency domain information contains the frequency , amplitude and phase , where i is an integer, .

[0073] In other words, after Fourier transform, the frequency of any point in a specific area Amplitude and phase is a known number, that is, the amplitude of a specific area is obtained The distribution and phase of distribution.

[0074] frequency The resulting signal changes over time as follows:

[0075] ;

[0076] Where, Indicates time, Indicates frequency, Represents the three-dimensional space coordinates, Frequency The amplitude of Frequency phase. Represents a point in space generated by the frequency The time domain signal, where i is an integer, .

[0077] Step 4: Calculate the frequency, amplitude, and phase characteristics of any position in the flow field as needed to obtain the flow field structure at different frequencies and complete the flow field decomposition.

[0078] The following takes the pressure field decomposition in the flow field as an example to illustrate the implementation process of this step:

[0079] Any point in the flow field pressure field , contains all frequency components and is the sum of the pressure fields caused by all frequencies. It can be decomposed into a series form:

[0080] ;

[0081] in, t Indicates time, is the three-dimensional space coordinate, is the average value of the pressure in the flow field (independent of time), Frequency The pressure field generated, i is an integer, .

[0082] The pressure field in a specific area Perform Fourier transform to obtain the frequency , amplitude and phase .

[0083] The decomposed pressure field can be obtained according to the following formula :

[0084] ;

[0085] Where, is the decomposed pressure field, t Indicates time, is the three-dimensional space coordinate Frequency The amplitude of is the phase of the frequency. pressure field After that, the purpose of decomposing the pressure field is achieved, where i is an integer, .

[0086] The present invention performs data processing on the calculation results through unsteady numerical calculations and adopts Fourier transform to obtain the spectral characteristics of the flow field. The flow field decomposition process based on Fourier transform is mathematically rigorously derived, and the obtained modes are strictly orthogonal. It can obtain the propagation characteristics of flow field fluctuations of specific frequencies and realize the study of flow field propagation characteristics in specific areas.

[0087] In addition to being applied to the field of hydraulic turbines, the present invention can also be extended to other fields such as fluid machinery and fluid mechanics. The flow field propagation characteristics of specific areas of fluid machinery can be studied according to needs, and the application prospects are broad.

[0088] Example 1

[0089] This embodiment provides a specific implementation method for analyzing the propagation of pressure fluctuations of a water turbine by using the present invention.

[0090] Static-dynamic interference is a significant factor affecting the stability of hydroturbine units, particularly the pressure pulsations and their propagation characteristics caused by this interference. This interference refers to the mutual flow interference between the rotating component (runner) and the stationary component (guide vanes). Under power generation conditions, the wake effect at the guide vane exit causes the runner blades to periodically cut through the wake region, affecting the pressure pulsation characteristics in this region. Under pumping conditions, the runner blade wake region interacts with the guide vanes, generating a static-dynamic interference effect. Therefore, in the rotating domain, the dominant frequency is the guide vane passage frequency and its multiples. In the stationary domain, the dominant frequency of pressure pulsations in the vaneless region is the blade passage frequency and its multiples. These pressure pulsations propagate upstream or circumferentially, where they are reflected and superimposed, producing phase resonance and other phenomena, seriously impacting the safe and stable operation of the unit.

[0091] The main frequency characteristics of dynamic and static interference are:

[0092] In the rotating domain (inside the rotor), the frequency of the pressure pulsation is the number of active guide vanes multiplied by the rotation frequency and its multiples, that is, ,in k is an integer, l is the number of movable guide vanes, f n is the rotation frequency. r represents the rotation domain, the subscript n Represents rotation.

[0093] In the static area (bladeless area, movable guide vane area, volute, etc.), the frequency of pressure pulsation is the number of runner blades multiplied by the rotation frequency and its multiples, that is, ,in k is an integer, m is the number of runner blades, f n is the rotation frequency. srepresents the stationary domain, the subscript n Represents rotation.

[0094] The specific implementation steps of the flow field propagation characteristic analysis method based on the numerical method of the present invention to analyze the propagation of the dynamic and static interference pressure fluctuations of the turbine are as follows:

[0095] Step 1: Pre-treatment

[0096] S1.1. The research object of this embodiment is a pump turbine (power generation condition). The calculation physical model includes five flow components, namely, volute 4, fixed guide vane 3, movable guide vane 2, runner 1 and tailwater pipe 5. Figure 5 As shown, the cross-sectional view of the calculated physical model along the AA surface is as follows Figure 6 shown.

[0097] S1.2. Divide the meshes of the five flow-through components (i.e., the computational fluid domain).

[0098] S1.3. Pre-processing of calculation files. The total pressure boundary condition is used for the volute inlet, the opening boundary condition is used for the tailwater pipe outlet, the solid wall boundary condition with a velocity of 0 is used for the volute wall, the fixed guide vane surface, the movable guide vane surface, the tailwater pipe surface, etc., and the rotating solid wall boundary condition is used for the runner solid wall. The steady calculation results (calculation independent of time) are used as the initial conditions. The discrete format uses the first-order upwind format, etc., and the residual is 10 -5 Set the calculation convergence condition, calculate one step every 2° rotation as the calculation time step, set the total calculation time to 10 rotation cycles, etc.

[0099] After setting, save the pre-processing file as aaa.def file.

[0100] Step 2: Perform unsteady calculations on the aaa.def file and obtain the calculation result file.

[0101] Keep the result files during the calculation process: 1.trn, 2.trn, 3.trn..., 3600.trn, and the final result file aaa-01.res file at the end of the calculation.

[0102] Step 3: Processing of unsteady calculation results.

[0103] S3.1. Extract the data from files 1.trn, 2.trn, 3.trn, ..., 3600.trn. The data includes the spatial coordinates (x, y, z) and the pressure P at the coordinate point, and save them.

[0104] S3.1.1. For model 1, extract the pressure field data inside the rotor from files 1.trn, 2.trn, 3.trn, ..., 3600.trn and save them.

[0105] S3.1.2, Model 2, extract the pressure field data of the bladeless area, movable guide vanes, fixed guide vanes, and volute from files 1.trn, 2.trn, 3.trn, ..., 3600.trn, and save them.

[0106] S3.2. Perform Fourier transform on the data to convert the time domain information of the pressure field P into frequency domain information.

[0107] From the frequency domain information, the amplitude distribution and phase distribution of the corresponding frequency can be obtained.

[0108] S3.3. Based on the amplitude distribution and phase distribution, the pressure field at the corresponding frequency is obtained, and the propagation characteristics of the pressure field can be obtained, that is, the dynamic-static interference effect is obtained.

[0109] Model 1 (9 runner blades, 22 movable guide vanes) dynamic and static interference - 22 in the runner f n The pressure variation characteristics of the frequency over time, where f n is the rotation frequency, T is the rotation period, f n =1 / T. Figure 2 In the figure, the arrows indicate the direction of propagation. Figure 2 (a) means 22 f n The amplitude distribution of the frequency, Figure 2 (b) means 22 f n Phase distribution of frequency, Figure 2 (c) means 22 f n Frequency-induced propagation characteristics of the pressure field. The subscript n indicates rotation.

[0110] Model 2 (9 runner blades, 20 movable guide vanes) dynamic and static interference - 18 in the static domain f n The pressure variation characteristics of the frequency over time, where f n is the rotation frequency, T is the rotation period, f n =1 / T. Figure 3 In the figure, the arrows indicate the direction of propagation. Figure 3 (a) means 18 f n The amplitude distribution of frequency, Figure 3 (b) means 18 f n Phase distribution of frequency, Figure 3 (c) means 18 fnFrequency-induced propagation characteristics of the pressure field. The subscript n indicates rotation.

[0111] This embodiment uses numerical methods to extract data such as pressure at grid nodes from the calculation result file and adopts Fourier transform to obtain the spatial distribution of blade pass frequency and its frequency multiplication amplitude and phase, thereby obtaining the spatial propagation characteristics of pressure fluctuations, thereby providing technical support for optimizing the dynamic-static interference effect and ensuring the safe and stable operation of the unit.

[0112] Example 2

[0113] The propagation of the pressure field of another frequency, 40Hz, in the volute. The amplitude of this frequency is relatively small in the volute, only 1 / 4 of the dynamic-static interference effect. Without the use of flow field decomposition technology, it is impossible to clearly obtain the propagation characteristics of the pressure field of this frequency component.

[0114] The propagation characteristics of the pressure field obtained by the method of the present invention are introduced below.

[0115] Step 1, step 2, and step 3 of this embodiment are the same as the implementation process of embodiment 1, except that the frequency is 40 Hz (relatively small amplitude) and the specific area (area for data extraction) is the volute.

[0116] The amplitude distribution and phase distribution of the 40Hz frequency after decomposition using this method are as follows: Figure 4 Propagation characteristics of the pressure field are shown. Figure 4 In the figure, the double-headed arrow indicates that the propagation direction is bidirectional. Figure 4 (a) shows the amplitude distribution of 40 Hz frequency, Figure 4 (b) shows the phase distribution at 40 Hz frequency. Figure 4 (c) shows the pressure field propagation caused by a frequency of 40 Hz.

[0117] Example 3

[0118] Based on the same inventive concept, this embodiment provides a flow field propagation characteristics analysis device based on a numerical method, including a pre-processing module, an unsteady calculation module, a data processing module and a flow field decomposition module.

[0119] The pre-processing module is configured to construct a computational physics model of a target flow field, perform fluid domain meshing on the computational physics model, and set computational boundary conditions, initial flow state, and numerical methods. In this embodiment, the target flow field includes the internal flow field of a fluid machinery.

[0120] The unsteady calculation module is configured to carry out unsteady calculations and obtain calculation result files;

[0121] The data processing module is configured to extract data from specific areas of the calculation result file grid according to research needs, convert the time domain information in the extracted data into frequency domain information through Fourier transform, and then obtain the frequency, amplitude and phase characteristic distribution of the flow field based on the frequency domain information;

[0122] The flow field decomposition module is configured to calculate any frequency, amplitude and phase characteristics in the flow field as needed, obtain the change of the flow field structure at different frequencies over time, and complete the flow field decomposition.

[0123] Furthermore, the flow field decomposition module calculates any frequency, amplitude, and phase characteristics in the flow field as needed to obtain the flow field structure at different frequencies, which can be expressed as follows:

[0124] ;

[0125] Where, is the decomposed flow field, such as pressure field, velocity field, etc. t Indicates time, is the three-dimensional space coordinate, Frequency The amplitude of Frequency Phase. Get different frequencies Flow field After that, the purpose of decomposing the flow field is achieved. i is an integer, .

[0126] Furthermore, the pre-processing module includes a model building unit, a grid division unit and a parameter setting unit.

[0127] The model building unit is configured to build a computational physical model of the flow-through components from the inlet to the outlet of the fluid machinery where the target flow field is located.

[0128] The meshing unit is configured to mesh the fluid domain of the computational physics model.

[0129] The parameter setting unit is configured to set the flow field boundary conditions, initial flow field flow state and numerical method of the fluid machinery inlet, outlet, solid surface, rotating and stationary interface. The set flow field boundary conditions include velocity, pressure, turbulence, and the set initial flow field flow state is the initial condition; the set numerical method includes discrete format, convergence condition, and calculation time step.

[0130] In this embodiment, any unfinished description of each functional module is consistent with the description in the method.

[0131] Example 4

[0132] This embodiment provides a flow field propagation characteristics analysis device based on a numerical method, including:

[0133] memory for storing computer programs;

[0134] A processor is used to implement the steps of the flow field propagation characteristics analysis method based on the numerical method as described in the above embodiment 1 when executing the computer program.

[0135] Preferably, the computer program can be divided into one or more modules / units, which are stored in the memory and executed by the processor to implement the present invention. The one or more modules / units can be a series of computer program instruction segments capable of implementing specific functions, and the instruction segments are used to describe the execution process of the computer program in the device.

[0136] The processor can be a central processing unit, or other general-purpose processors, digital signal processors, application-specific integrated circuits, off-the-shelf programmable gate arrays or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor, or the processor can also be any conventional processor. The processor is the control center of the device, and various parts of the device are connected using various interfaces and lines.

[0137] The memory mainly includes a program storage area and a data storage area. The program storage area can store the operating system, at least one application required for a function, etc., and the data storage area can store related data, etc. In addition, the memory can be a high-speed random access memory, or a non-volatile memory such as a plug-in hard disk, a smart memory card, a secure digital card, and a flash memory card, or the memory can also be other volatile solid-state memory devices.

[0138] Example 5

[0139] An embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps in the flow field propagation characteristics analysis method based on the numerical method are implemented.

[0140] Computer storage media may be tangible media that can contain or store programs for use by or in connection with an instruction execution system, apparatus, or device.

[0141] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A flow field propagation characteristics analysis method based on numerical methods, characterized in that: The steps include: Construct a computational physics model of the target flow field, mesh the fluid domain of the computational physics model, and set the flow field boundary conditions, initial flow state, and numerical method; Carry out unsteady calculations and obtain calculation result files; Extract data from specific areas of the calculation result file grid according to research needs, convert the time domain information in the extracted data into frequency domain information through Fourier transform, and then obtain the frequency, amplitude and phase characteristic distribution of the flow field based on the frequency domain information; The frequency, amplitude and phase characteristics of any position in the flow field are calculated as needed to obtain the flow field structure at different frequencies, thus completing the flow field decomposition. The decomposed flow field is expressed as follows: ； Where, is the decomposed flow field, t Indicates time, is the three-dimensional space coordinate, Frequency The amplitude of Frequency Phase; i is an integer, .

2. The method for analyzing flow field propagation characteristics based on numerical methods according to claim 1, characterized in that: The target flow field includes the internal flow field of the fluid machinery; the fluid machinery includes turbines and water pumps, and the corresponding computational physical model is the flow-through components of the fluid machinery from inlet to outlet, including the volute, fixed guide vanes, movable guide vanes, runner and tailwater pipe.

3. The flow field propagation characteristics analysis method based on numerical methods according to claim 2, characterized in that: The internal flow field of the fluid machinery includes an inlet, an outlet, a solid surface, and rotating and stationary interfaces; the set flow field boundary conditions include velocity, pressure, and turbulence; the set initial flow state of the flow field, i.e., the initial conditions; and the set numerical method includes a discrete format, convergence conditions, and a calculation time step.

4. The method for analyzing flow field propagation characteristics based on numerical methods according to claim 2 or 3, characterized in that: The internal flow field of the fluid machinery obtained based on the unsteady calculation results is expressed as , Contains all frequency components and is the sum of the flow fields caused by all frequencies, expressed in series as: ； Where, is the flow field, is the mean flow field, Indicated by frequency The time-dependent flow field caused by t Indicates time, is the three-dimensional space coordinate, i is an integer.

5. A flow field propagation characteristics analysis device based on numerical methods, characterized in that: include: a pre-processing module configured to construct a computational physics model of a target flow field, mesh the computational physics model in the fluid domain, and set flow field boundary conditions, initial flow state, and numerical methods; the target flow field includes an internal flow field of a fluid machinery; an unsteady calculation module, wherein the unsteady calculation module is configured to perform unsteady calculations and obtain calculation result files; A data processing module is configured to extract data from a specific area in the calculation result file grid according to research needs, convert the time domain information in the extracted data into frequency domain information through Fourier transform, and then obtain the frequency, amplitude and phase characteristic distribution of the flow field based on the frequency domain information; The flow field decomposition module is configured to calculate the frequency, amplitude and phase characteristics of any position in the flow field as needed, obtain the flow field structure at different frequencies, and complete the flow field decomposition.

6. The flow field propagation characteristics analysis device based on numerical methods according to claim 5, characterized in that: The flow field decomposition module calculates the frequency, amplitude and phase characteristics of any position in the flow field as needed to obtain the flow field structure at different frequencies, which can be expressed as follows: ； Where, is the decomposed flow field, t Indicates time, is the three-dimensional space coordinate, Frequency The amplitude of Frequency The phase, i is an integer, .

7. The flow field propagation characteristics analysis device based on numerical methods according to claim 5, characterized in that: The pre-processing module includes: A model building unit, the model building unit being configured to build a computational physical model of a flow-through component from an inlet to an outlet of a fluid machinery where a target flow field is located; a grid division unit configured to perform grid division on a fluid domain of a computational physics model; A parameter setting unit, wherein the parameter setting unit is configured to set the flow field boundary conditions, the flow field flow state at the initial moment and the numerical method of the fluid machinery inlet, outlet, solid surface, rotating and stationary interface. The set flow field boundary conditions include velocity, pressure, and turbulence. The set flow field flow state at the initial moment is the initial condition; the set numerical method includes the discrete format, convergence condition, and calculation time step.

8. A flow field propagation characteristics analysis device based on numerical methods, characterized in that: include: memory for storing computer programs; A processor is configured to implement the steps of the flow field propagation characteristics analysis method based on a numerical method as claimed in any one of claims 1 to 4 when executing the computer program.

9. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps in the flow field propagation characteristics analysis method based on a numerical method according to any one of claims 1 to 4 are implemented.

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