Flow field propagation characteristic analysis method and device based on numerical method, equipment and medium

Abstract

The invention discloses a flow field propagation characteristic analysis method, device and equipment based on a numerical method and a medium, and belongs to the technical field of water turbines. Comprising the following steps: constructing a computational physical model of a target flow field, performing fluid domain grid division on the computational physical model, and setting a flow field boundary condition, an initial moment flow field flow state and a numerical method; extracting data of a specific area in the grid according to research needs to carry out unsteady calculation, and obtaining a calculation result file; converting time domain information in the extracted data into frequency domain information through Fourier transform, and obtaining frequency, amplitude and phase feature distribution of the flow field according to the frequency domain information; and calculating the frequency, the amplitude and the phase characteristics of any position in the flow field as required to obtain flow field structures under different frequencies, and completing flow field decomposition. By adopting the method, the flow field propagation characteristics of the fluid machinery in a specific area can be researched according to requirements.

Description

Technical Field

[0001] The present invention relates to the field of research on flow field propagation characteristics, and particularly to an analysis method, device, equipment and medium for flow field propagation characteristics based on numerical methods. Background Technique

[0002] In engineering, sometimes it is necessary to understand the propagation characteristics of certain important characteristic frequencies in the flow field (such as the blade passing frequency, guide vane passing frequency or a certain special frequency caused by the interaction between the moving and static parts) to evaluate the impact on the vibration of the structure. The flow field structure obtained by numerical calculation or experimental measurement, such as the pressure field, is the manifestation of the superposition of pressure pulsations and average pressure at various frequencies. In other words, the flow field structure is the result of the combined action of various components. For the contribution, propagation and other characteristics of a certain frequency component, if relevant modal decomposition methods are not adopted, they cannot be learned.

[0003] To study the flow field propagation characteristics, flow field decomposition is required. Currently, the main flow field decomposition methods for the inside of hydraulic turbines or other fields are proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) and their deformations. For example, Paper 1: Kou Jiaqing, Zhang Weiwei, Gao Chuanqiang. Transonic buffet mode analysis based on POD and DMD methods [J]. Acta Aeronautica et Astronautica Sinica, 2016, 37(9): 2679-2689. Paper 2: Kou Jiaqing, Zhang Weiwei. Dynamic mode decomposition and its application in fluid mechanics [J]. Acta Aerodynamica Sinica, 2018, 36(2): 163-179. In the above two papers by Kou Jiaqing et al., a relatively comprehensive analysis of the POD and DMD methods was carried out. These two modal methods require matrix operations on the flow field information (vector) to obtain the eigenvalues and eigenvectors of the matrix. Since the POD method has no requirement for time series, its main disadvantage is that the extracted modes have no frequency domain characteristics and can only extract the main characteristics of the internal flow field from the perspective of energy, making it difficult to predict the wave propagation characteristics inside the hydraulic turbine. 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.

[0004] Therefore, the current flow field decomposition methods have two disadvantages: one is that the matrix operation amount is large and the error of the calculated high-order eigenvalues (eigenvectors) is large; the other is that the eigenvalues and eigenvectors have no specific physical meaning. And currently, no research on the flow field wave propagation characteristics using these two methods has been found.

[0005] In the prior art, the Chinese invention patent with the publication number CN108801588A discloses a visualization frequency domain analysis method for internal flow field characteristic quantities of hydraulic machinery. This patent first performs Fourier transform on one-dimensional flow field characteristic signals to obtain frequency and amplitude characteristics, and then uses cross-spectrum analysis of multi-point monitoring values to obtain the phase difference in the axial or circumferential direction, thereby obtaining the propagation characteristics of the flow in the axial or circumferential direction. However, this method still has the following defects: First, only two-dimensional information can be obtained through this scheme, and the propagation characteristics of the flow field in any direction cannot be obtained; second, the number of monitoring points in this scheme is limited, and distortion may occur. Summary of the Invention

[0006] The present invention aims to solve the deficiencies existing in the current flow field decomposition method in the study of flow field propagation characteristics, and proposes a flow field propagation characteristic analysis method, device, equipment and medium based on numerical methods. Through the present invention, the flow field propagation characteristics of specific regions of fluid machinery can be studied according to requirements.

[0007] In order to achieve the above-mentioned invention purpose, the technical solution of the present invention is as follows: A flow field propagation characteristic analysis method based on numerical methods, including the following steps: Construct a computational physical model of the target flow field, perform fluid domain mesh division on the computational physical model, and set flow field boundary conditions, the flow state of the flow field at the initial moment, and numerical methods; Carry out unsteady calculations and obtain a calculation result file; Extract data of specific regions 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 distributions of the flow field according to the frequency domain information; Calculate the frequency, amplitude and phase characteristics at any position in the flow field according to needs, and obtain the flow field structure at different frequencies, that is, complete the flow field decomposition; The decomposed flow field is represented by the following formula: ; In the formula, is the decomposed flow field, t represents time, is the three-dimensional space coordinate, is the frequency of the amplitude, is the frequency of the phase; i is an integer, i =0, 1, 2, 3, ….

[0008] Preferably, the target flow field includes the internal flow field of a fluid machine, and the fluid machine includes a water turbine and a water pump; the corresponding computational physical model is the flow-through components of the fluid machine from the inlet to the outlet, including a volute, stay vanes, guide vanes, runner, and draft tube.

[0009] Preferably, the internal flow field of the fluid machine includes an inlet, an outlet, a solid surface, a rotating and stationary interface; the set flow field boundary conditions include velocity, pressure, and turbulence; the set initial flow field state at the initial moment is the initial condition; the set numerical methods include discretization format, convergence condition, and computational time step.

[0010] Furthermore, the internal flow field of the fluid machine obtained according to the unsteady calculation results is expressed as ; It contains all frequency components and is the sum of the flow fields caused by all frequencies, expressed as a series as: ; In the formula, is the flow field, is the mean flow field, represents the time-dependent flow field caused by the frequency ; t represents time, is the three-dimensional space coordinate, i is an integer.

[0011] The present invention also proposes an analysis device for the flow field propagation characteristics based on numerical methods, including: A preprocessing module configured to construct a computational physical model of the target flow field, perform fluid domain mesh division on the computational physical model, and set flow field boundary conditions, the initial flow field state at the initial moment, and numerical methods, where the target flow field includes the internal flow field of a fluid machine; An unsteady calculation module configured to perform unsteady calculations and obtain a calculation result file; A data processing module configured to extract data in a specific area in the grid of the calculation result file 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 distributions of the flow field according to the frequency domain information; A flow field decomposition module configured to calculate the frequency, amplitude, and phase characteristics at any position in the flow field as needed, obtain the flow field structures at different frequencies, and complete the flow field decomposition.

[0012] Preferably, the flow field decomposition module calculates the frequency, amplitude, and phase characteristics at any position in the flow field as needed to obtain the flow field structures at different frequencies, expressed by the formula as follows: ; In the formula, is the decomposed flow field, t represents time, is the three-dimensional space coordinate, is the frequency amplitude, is the frequency phase, i is an integer, i = 0, 1, 2, 3, ….

[0013] Preferably, the preprocessing module includes: A model construction unit configured to construct a computational physical model of the flow components of the fluid machine where the target flow field is located from the inlet to the outlet; A mesh generation unit configured to generate a mesh for the fluid domain of the computational physical model; A parameter setting unit configured to set the flow field boundary conditions, the flow field state at the initial moment, and the numerical method for the fluid machine inlet, outlet, solid surface, rotating and stationary interfaces. The set flow field boundary conditions include velocity, pressure, and turbulence. The set flow field state at the initial moment is the initial condition. The set numerical method includes the discretization format, convergence condition, and computational time step.

[0014] Furthermore, the present invention also provides a flow field propagation characteristic analysis device based on a numerical method, including: A memory for storing a computer program; A processor for implementing the steps in the above-mentioned flow field propagation characteristic analysis method based on a numerical method when executing the computer program.

[0015] The present invention also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps in the above-mentioned flow field propagation characteristic analysis method based on a numerical method are implemented.

[0016] In summary, the present invention has the following advantages: 1. Through unsteady numerical calculations, the present invention processes the calculation results, performs Fourier transform, obtains the spectral characteristics of the flow field, and the mathematical derivation of the flow field decomposition process based on Fourier transform is rigorous. The obtained modes are strictly orthogonal, enabling the acquisition of the propagation characteristics of the flow field fluctuations at specific frequencies and realizing the research on the flow field propagation characteristics in a specific region; 2. When the present invention decomposes the flow field, it can extract a large amount of grid data from the calculation result file according to requirements. According to the spatial distribution of data points, the spatial distributions of specific frequency phases and amplitudes can be obtained, which is very beneficial for studying the propagation characteristics of flow field fluctuations. 3. In addition to being applied to the field of hydraulic turbines, the present invention can also be extended to other fields such as other fluid machinery and fluid mechanics. It can study the flow field propagation characteristics of specific regions of fluid machinery according to requirements, such as the propagation of dynamic and static interference pressure fluctuations in hydraulic turbines, etc., and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is the implementation flowchart of the present invention; Figure 2 shows the propagation characteristics of the pressure field in the rotating domain in Embodiment 1 of the present invention. In the figure, (a) represents the amplitude distribution at 22 f n frequency, (b) represents the phase distribution at 22 f n frequency, and (c) represents the propagation characteristics of the pressure field caused by 22 f n frequency; Figure 3 shows the propagation characteristics of the pressure field in the stationary domain in Embodiment 1 of the present invention. In the figure, (a) represents the amplitude distribution at 18 f n frequency, (b) represents the phase distribution at 18 f n frequency, and (c) represents the propagation characteristics of the pressure field caused by 18 f n frequency; Figure 4 shows the propagation of the pressure at 40 Hz frequency in the volute in Embodiment 2 of the present invention. In the figure, (a) represents the amplitude distribution at 40 Hz frequency, (b) represents the phase distribution at 40 Hz frequency, and (c) represents the propagation of the pressure field caused by 40 Hz frequency; Figure 5 is the computational physical model of the main flow-through components of the hydraulic turbine, and a distance is opened between the 5 flow-through components; Figure 6 is Figure 5 a sectional view along the A-A plane, observed in the Z direction.

[0018] In the figure: 1. Runner, 2. Guide vane, 3. Stay vane, 4. Volute, 5. Draft tube.

[0019] Description of the colors in the drawings: Red represents a large value. The redder it is, the larger the value. Blue represents a small value. The bluer it is, the smaller the value. Other colors represent values between the maximum and minimum values, following the same color distribution pattern as the rainbow: red → orange → yellow → green → blue → indigo → violet. Detailed implementation manners

[0020] To more clearly illustrate the present invention, the present invention will be further described below in conjunction with preferred embodiments and the drawings. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention.

[0021] The present invention provides a method for analyzing the flow field propagation characteristics based on numerical methods, as Figure 1 shown, including the following steps: Step 1: Construct a computational physical model of the target flow field, perform fluid domain mesh division on the computational physical model, and set the flow field boundary conditions, the flow field flow state at the initial moment, and the numerical method.

[0022] In this step, the target flow field can be the internal flow field of a fluid machinery. The fluid machinery applicable to this solution includes, but is not limited to, water turbines and water pumps. The corresponding computational physical model is the flow-through components from the inlet to the outlet, including the volute, stay vanes, guide vanes, runner, draft tube, etc.

[0023] In this step, the fluid domain mesh division of the computational physical model can be implemented using existing mesh division software.

[0024] In this step, the internal flow field of the fluid machinery includes the pressure field, velocity field, etc. of the internal fluid domain of the flow-through components from the inlet to the outlet. The set flow field boundary conditions include velocity, pressure, turbulence, etc.; the set flow field flow state at the initial moment is the initial condition; the set numerical method includes discrete format, convergence condition, computational time step, etc.

[0025] Step 2: Conduct unsteady calculations and obtain the calculation result file.

[0026] In this step, the result file and the final result file during the calculation process are retained.

[0027] 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: ; In the formula, is the flow field, such as the pressure field, velocity field, etc., is the mean flow field (independent of time), Represents the time - related flow field caused by the frequency t Represents time, is the three - dimensional space coordinate, i is an integer.

[0028] Step 3: Extract the data in a specific area of the result file grid according to the 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 distributions of the flow field based on the frequency - domain information.

[0029] In this step, extract the data in a specific area of the calculation result file according to the research needs. The specific area can be, for example, the runner area, the movable guide vane area, etc. The data in the specific area includes data such as spatial position coordinates and flow - field physical quantities. For example, if the researcher needs to study the dynamic - static interference effect in the movable guide vane area, the data in the movable guide vane area should be extracted, and the data of the fixed guide vane and the volute can also be considered for addition.

[0030] In this step, by directly extracting the data in the result file grid of the calculation, it can be ensured that the number of data points is large (in the case of unsteady calculations, the number of grid nodes is in the order of hundreds of thousands or even millions); moreover, according to the spatial distribution of the data points, the spatial distributions of specific frequencies, phases, and amplitudes can be obtained, which is very beneficial for studying the propagation characteristics of flow - field fluctuations.

[0031] In this step, the time - domain information is the information related to time and is extracted from the result file retained during the calculation process.

[0032] The Fourier - transform formula is as follows: ;

[0033] In the formula, represents the signal in the time domain, represents the frequency - domain signal after Fourier transform; represents time, represents the natural constant, represents the frequency, represents the imaginary unit, represents the three - dimensional space coordinate.

[0034] After Fourier transform, a series of frequencies , amplitudes and phases are obtained. In the formula, i is an integer, .

[0035] In this step, the amplitude and phase of the obtained frequency ​The spatial coordinates are included in the frequency-domain information , that is, after Fourier transform, the frequency-domain information includes frequency , amplitude and phase . In the formula, i is an integer, .

[0036] In other words, after Fourier transform, the amplitude and phase of the frequency at any point in a specific region are known numbers, that is, the distribution of the amplitude and the distribution of the phase in the specific region are obtained

[0037] The formula for the signal generated by the frequency changing with time is: ;

[0038] In the formula, represents time, represents frequency, represents the three-dimensional spatial coordinates, is the amplitude of the frequency , is the phase of the frequency . represents the time-domain signal of the spatial point generated by the frequency. In the formula, i is an integer, .

[0039] Step 4: Calculate the frequency, amplitude, and phase characteristics at any position in the flow field as needed to obtain the flow field structure at different frequencies and complete the flow field decomposition

[0040] The following takes the decomposition of the pressure field in the flow field as an example to illustrate the implementation process of this step The pressure field at any point in the flow field contains all frequency components and is the sum of the pressure fields caused by all frequencies, which can be decomposed into a series form ; wherein, t represents time, are the three-dimensional spatial coordinates, is the average value of the pressure in the flow field (independent of time), is the pressure field generated by the frequency , i is an integer, .

[0041] Perform a Fourier transform on the pressure field in a specific region to obtain the frequency , amplitude and phase .

[0042] The decomposed pressure field can be obtained according to the following formula : ; In the formula, is the decomposed pressure field, t represents time, is the three-dimensional space coordinate is the frequency is the amplitude of the frequency, is the phase of the frequency. After obtaining the pressure fields at different frequencies , the purpose of decomposing the pressure field is achieved. In the formula, is an integer, i . .

[0043] Through unsteady numerical calculations, data processing of the calculation results is carried out, and Fourier transform is used to obtain the spectral characteristics of the flow field. The mathematical derivation of the flow field decomposition process based on Fourier transform is rigorous, and the obtained modes are strictly orthogonal, enabling the acquisition of the propagation characteristics of flow field fluctuations at specific frequencies and realizing the study of the flow field propagation characteristics in a specific region.

[0044] 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, and can study the flow field propagation characteristics in specific regions of fluid machinery according to requirements, with broad application prospects.

[0045] Embodiment 1 This embodiment gives a specific implementation method for analyzing the pressure fluctuation propagation of the dynamic and static interference of a hydraulic turbine using the present invention.

[0046] Dynamic and static interference is an important factor affecting the stability of hydraulic turbine units, especially the pressure pulsation and its propagation characteristics caused by dynamic and static interference. So-called dynamic and static interference refers to the mutual interference of the flow between the rotating component (runner) and the stationary component (guide vane). Under the power generation condition, due to the wake effect at the outlet of the guide vane, the runner blades periodically cut the wake region, thus affecting the pressure pulsation characteristics of the wake region; under the pumping condition, the wake region of the runner blades will act on the guide vane, generating a dynamic and static interference effect. Therefore, in the rotating domain, its main frequency is the guide vane passing frequency and its multiples; for the pressure pulsation in the non-blade region of the stationary domain, its main frequency is the blade passing frequency and its multiples. The pressure pulsations at these frequencies propagate upstream or circumferentially in the flow passage, reflect and superimpose, resulting in phenomena such as phase resonance, seriously affecting the safe and stable operation of the unit.

[0047] The main frequency characteristics of the dynamic-static interference are as follows: In the rotating domain (inside the runner), the frequency of the pressure pulsation is the number of active guide vanes multiplied by the rotational frequency and its multiple frequencies, i.e., , where k is an integer, l is the number of active guide vanes, f n is the rotational frequency. The subscript r represents the rotating domain, and the subscript n represents rotation.

[0048] In the stationary domain (the vaneless space, the active guide vane area, the volute, etc.), the frequency of the pressure pulsation is the number of runner blades multiplied by the rotational frequency and its multiple frequencies, i.e., , where k is an integer, m is the number of runner blades, f n is the rotational frequency. The subscript s represents the stationary domain, and the subscript n represents rotation.

[0049] The specific implementation steps for analyzing the propagation of the dynamic-static interference pressure fluctuation of a hydraulic turbine by using the flow field propagation characteristic analysis method based on the numerical method of the present invention are as follows: Step 1: Pretreatment S1.1. The research object of this embodiment is a pump-turbine (power generation condition). The computational physical model includes five flow-through components, namely, the volute 4, the stay vane 3, the active guide vane 2, the runner 1, and the draft tube 5. As Figure 5 shown, the cross-sectional view of the computational physical model along the A-A plane is as Figure 6 shown.

[0050] S1.2. Mesh generation is performed on these five flow-through components (i.e., the computational fluid domain).

[0051] S1.3. Pretreatment of the calculation file. The total pressure boundary condition is adopted at the inlet of the volute, the opening boundary condition is adopted at the outlet of the draft tube, and the solid wall boundary condition with a velocity of 0 is adopted for the walls of the volute, the surfaces of the stay vanes, the surfaces of the active guide vanes, the surfaces of the draft tube, etc. The rotating solid wall boundary condition is adopted for the solid wall of the runner; the steady calculation result (a calculation independent of time) is used as the initial condition; the first-order upwind scheme is adopted for the discretization format, and the residual is set to 10 -5 as the calculation convergence condition, and one step is calculated every 2° of rotation as the calculation time step, and the total calculation time length is set to 10 rotation periods, etc.

[0052] After setting, save the pretreatment file as the aaa.def file.

[0053] Step 2: Conduct unsteady calculations on the aaa.def file and obtain the calculation result file.

[0054] Retain the result files during the calculation process: 1.trn, 2.trn, 3.trn ……, 3600.trn, and the final result file aaa-01.res at the end of the calculation.

[0055] Step 3: Process the unsteady calculation results.

[0056] S3.1: Extract the data from files 1.trn, 2.trn, 3.trn ……, 3600.trn. The data includes the spatial point coordinates (x, y, z) and the pressure P at this coordinate point, and save it.

[0057] S3.1.1: For Model 1, extract the pressure field data inside the runner from files 1.trn, 2.trn, 3.trn ……, 3600.trn and save it.

[0058] S3.1.2: For Model 2, extract the pressure field data in the bladeless area, movable guide vanes, fixed guide vanes, and volute from files 1.trn, 2.trn, 3.trn ……, 3600.trn and save it.

[0059] S3.2: Perform Fourier transform on the data to convert the time-domain information of the pressure field P into frequency-domain information.

[0060] From the frequency-domain information, the amplitude distribution and phase distribution of the corresponding frequencies can be obtained.

[0061] S3.3: Based on the amplitude distribution and phase distribution, obtain the pressure field at the corresponding frequencies, and the propagation characteristics of the pressure field can be obtained, that is, the stator-rotor interaction effect is obtained.

[0062] Stator-rotor interaction of Model 1 (9 runner blades, 22 movable guide vanes) - Inside the runner 22 f n The variation characteristics of the pressure with time at the frequency, where f n is the rotational frequency and T is the rotational period, f n = 1 / T. Figure 2 In, the arrow indicates the propagation direction, Figure 2 (a) represents the amplitude distribution at 22 f n frequency, Figure 2 (b) represents the phase distribution at 22 f n frequency, Figure 2 (c) represents at 22 f nPropagation characteristics of the pressure field caused by frequency. Subscript n represents rotation.

[0063] Static-dynamic interference of Model 2 (9 runner blades, 20 guide vanes) - 18 in the stationary domain f n Characteristics of the pressure varying with time at 18 f n is the rotation frequency, and T is the rotation period, f n = 1 / T. Figure 3 In, the arrow indicates the propagation direction, Figure 3 (a) represents the amplitude distribution at 18 f n frequencies, Figure 3 (b) represents the phase distribution at 18 f n frequencies, Figure 3 (c) represents the propagation characteristics of the pressure field caused by 18 fn frequencies. Subscript n represents rotation.

[0064] In this embodiment, numerical means are used to obtain the spatial distribution of the amplitude and phase of the blade passing frequency and its multiple frequencies by extracting data such as pressure at the grid nodes in the calculation result file and using Fourier transform, so as to obtain the spatial propagation characteristics of the pressure fluctuation, and further provide technical support for optimizing the static-dynamic interference effect and ensuring the safe and stable operation of the unit.

[0065] Example 2 Other frequencies - Propagation of the pressure field at 40 Hz in the volute. The amplitude of this frequency is relatively small in the volute, only 1 / 4 of the static-dynamic interference effect. Without using the flow field decomposition technology, it will be impossible to clearly obtain the propagation characteristics of the pressure field of this frequency component.

[0066] The following introduces the propagation characteristics of the pressure field obtained by the method of the present invention.

[0067] Steps 1, 2, and 3 of this embodiment are the same as the implementation process of Example 1, except that the frequency is 40 Hz (with a relatively small amplitude) and the specific area (the area for data extraction) is the volute.

[0068] After decomposition by this method, the amplitude distribution and phase distribution at 40 Hz are obtained, and the propagation characteristics of the pressure field are as shown in Figure 4 shown. Figure 4 In, the double-headed arrow indicates that the propagation direction is two-way propagation, Figure 4 (a) represents the amplitude distribution at 40 Hz, Figure 4 (b) represents the phase distribution at 40 Hz, Figure 4 (c) represents the propagation of the pressure field caused by 40 Hz.

[0069] Embodiment 3 Based on the same inventive concept, this embodiment provides an analysis device for the propagation characteristics of a flow field based on a numerical method, including a preprocessing module, an unsteady calculation module, a data processing module, and a flow field decomposition module.

[0070] The preprocessing module is configured to construct a computational physical model of the target flow field, perform fluid domain mesh division on the computational physical model, and set computational boundary conditions, the flow field flow state at the initial moment, and the numerical method; in this embodiment, the target flow field includes the internal flow field of a fluid machine. The unsteady calculation module is configured to carry out unsteady calculations and obtain a calculation result file. The data processing module is configured to extract data in a specific area 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 distributions of the flow field according to the frequency domain information. 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 over time at different frequencies, and complete the flow field decomposition.

[0071] 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 is expressed by the following formula: ; In the formula, is the decomposed flow field, such as the pressure field, velocity field, etc., t represents time, is the three-dimensional space coordinate, is the frequency is the amplitude of the frequency is the frequency is the phase of the frequency After obtaining the flow fields at different frequencies , the purpose of flow field decomposition is achieved. In the formula, i is an integer, .

[0072] Furthermore, the preprocessing module includes a model construction unit, a mesh division unit, and a parameter setting unit.

[0073] The model construction unit is configured to construct a computational physical model of the flow components from the inlet to the outlet of the fluid machine where the target flow field is located.

[0074] The mesh division unit is configured to perform mesh division on the fluid domain of the computational physical model.

[0075] 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 for the fluid machinery inlet, outlet, solid surface, rotating and stationary interfaces. The set flow field boundary conditions include velocity, pressure, and turbulence. The flow field flow state at the initial moment is the initial condition. The set numerical method includes the discretization format, convergence condition, and calculation time step.

[0076] For the parts not described in each functional module in this embodiment, they are consistent with the descriptions in the method.

[0077] Embodiment 4 This embodiment provides an analysis device for the flow field propagation characteristics based on a numerical method, including: A memory for storing a computer program; A processor for implementing the steps of the method for analyzing the flow field propagation characteristics based on the numerical method as described in Embodiment 1 above when executing the computer program.

[0078] Preferably, the computer program can be divided into one or more modules / units. The one or more modules / units are stored in the memory and executed by the processor to complete the present invention. The one or more modules / units can be a series of computer program instruction segments capable of performing specific functions, and these instruction segments are used to describe the execution process of the computer program in the device.

[0079] 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 connects various parts of the device through various interfaces and lines.

[0080] The memory mainly includes a program storage area and a data storage area. Among them, the program storage area can store an operating system, application programs required for at least one function, etc., and the data storage area can store relevant 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, etc., or the memory can also be other volatile solid-state storage devices.

[0081] Embodiment 5 The embodiment of the present invention also provides a computer-readable storage medium. A computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the steps in the method for analyzing the flow field propagation characteristics based on the numerical method as described above are implemented.

[0082] A computer storage medium can be a tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device.

[0083] As described above, the above are only the preferred embodiments of the present invention, and do not impose any formal limitations on the present invention. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention all fall within the protection scope of the present invention.

Claims

1. A method for analyzing the propagation characteristics of a flow field based on a numerical method, characterized in that, It includes the following steps: Construct a computational physical model of the target flow field, perform fluid domain grid division on the computational physical model, and set the flow field boundary conditions, the flow state of the flow field at the initial moment, and the numerical method; Carry out unsteady calculations and obtain the calculation result file; Extract data of specific regions in the grid of the calculation result file 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 distributions of the flow field based on the frequency-domain information; Calculate the frequency, amplitude, and phase characteristics at any position in the flow field as needed to obtain the flow field structures at different frequencies, that is, complete the flow field decomposition; The decomposed flow field is expressed by the following formula: ； In the formula, is the decomposed flow field, t represents time, is the three-dimensional space coordinate, is the frequency amplitude, is the frequency phase; i is an integer, .

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

3. The method for analyzing the propagation characteristics of a flow field based on a numerical method according to claim 2, characterized in that, The internal flow field of the fluid machinery includes the inlet, outlet, solid surface, rotating and stationary interfaces; the set flow field boundary conditions include velocity, pressure, and turbulence; the set flow state of the flow field at the initial moment is the initial condition; the set numerical method includes the discretization format, convergence condition, and calculation time step.

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

5. An apparatus for analyzing the propagation characteristics of a flow field based on a numerical method, characterized in that, It includes: A preprocessing module configured to construct a computational physical model of the target flow field, perform fluid domain grid division on the computational physical model, and set the flow field boundary conditions, the flow state of the flow field at the initial moment, and the numerical method; the target flow field includes the internal flow field of fluid machinery; An unsteady calculation module configured to carry out unsteady calculations and obtain the calculation result file; A data processing module configured to extract data of specific regions in the grid of the calculation result file 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 distributions of the flow field based on the frequency-domain information; A flow field decomposition module configured to calculate the frequency, amplitude, and phase characteristics at any position in the flow field as needed to obtain the flow field structures at different frequencies and complete the flow field decomposition.

6. The apparatus for analyzing the propagation characteristics of a flow field based on a numerical method according to claim 5, characterized in that, The flow field decomposition module calculates the frequency, amplitude, and phase characteristics at any position in the flow field as needed to obtain the flow field structures at different frequencies, which is expressed by the formula as follows: ； In the formula, is the decomposed flow field, t represents time, is the three-dimensional space coordinate, is the frequency amplitude, is the frequency phase, i is an integer, .

7. The apparatus for analyzing the propagation characteristics of a flow field based on a numerical method according to claim 5, characterized in that, The preprocessing module includes: A model construction unit configured to construct a computational physical model of the flow-through components of the fluid machinery where the target flow field is located from the inlet to the outlet; A grid division unit configured to perform grid division on the fluid domain of the computational physical model; A parameter setting unit configured to set the flow field boundary conditions, the flow state of the flow field at the initial moment, and the numerical method for the inlet, outlet, solid surface, rotating and stationary interfaces of the fluid machinery. The set flow field boundary conditions include velocity, pressure, and turbulence, and the set flow state of the flow field at the initial moment is the initial condition; the set numerical method includes the discretization format, convergence condition, and calculation time step.

8. An equipment for analyzing the propagation characteristics of a flow field based on a numerical method, characterized in that, It includes: A memory for storing computer programs; A processor, which is configured to implement the steps in the numerical method-based flow field propagation characteristic analysis method according to any one of claims 1 to 4 when executing the computer program.

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

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